Merge remote-tracking branch 'upstream/master'

WORKSPACE

@@ -76,3 +76,10 @@ api_dependencies()
 load("@io_bazel_rules_go//go:deps.bzl", "go_rules_dependencies", "go_register_toolchains")
 go_rules_dependencies()
 go_register_toolchains()
+
+
+load("@build_bazel_rules_apple//apple:repositories.bzl", "apple_rules_dependencies")
+apple_rules_dependencies()
+
+load("@build_bazel_apple_support//lib:repositories.bzl", "apple_support_dependencies")
+apple_support_dependencies()

bazel/generate_objc.bzl

@@ -0,0 +1,215 @@
+load(
+    "//bazel:protobuf.bzl",
+    "get_include_protoc_args",
+    "get_plugin_args",
+    "proto_path_to_generated_filename",
+)
+load(":grpc_util.bzl", "to_upper_camel_with_extension",)
+
+_GRPC_PROTO_HEADER_FMT = "{}.pbrpc.h"
+_GRPC_PROTO_SRC_FMT = "{}.pbrpc.m"
+_PROTO_HEADER_FMT = "{}.pbobjc.h"
+_PROTO_SRC_FMT = "{}.pbobjc.m"
+_GENERATED_PROTOS_DIR = "_generated_protos"
+
+_GENERATE_HDRS = 1
+_GENERATE_SRCS = 2
+_GENERATE_NON_ARC_SRCS = 3
+
+def _generate_objc_impl(ctx):
+    """Implementation of the generate_objc rule."""
+    protos = [
+        f
+        for src in ctx.attr.deps
+        for f in src[ProtoInfo].transitive_imports.to_list()
+    ]
+
+    target_package = _join_directories([ctx.label.workspace_root, ctx.label.package])
+
+    files_with_rpc = [_label_to_full_file_path(f, target_package) for f in ctx.attr.srcs]
+
+    outs = []
+    for proto in protos:
+        outs += [_get_output_file_name_from_proto(proto, _PROTO_HEADER_FMT)]
+        outs += [_get_output_file_name_from_proto(proto, _PROTO_SRC_FMT)]
+
+        file_path = _get_full_path_from_file(proto)
+        if file_path in files_with_rpc:
+            outs += [_get_output_file_name_from_proto(proto, _GRPC_PROTO_HEADER_FMT)]
+            outs += [_get_output_file_name_from_proto(proto, _GRPC_PROTO_SRC_FMT)]
+    
+    out_files = [ctx.actions.declare_file(out) for out in outs]
+    dir_out = _join_directories([
+        str(ctx.genfiles_dir.path), target_package, _GENERATED_PROTOS_DIR
+    ])
+
+    arguments = []
+    if ctx.executable.plugin:
+        arguments += get_plugin_args(
+            ctx.executable.plugin,
+            [],
+            dir_out,
+            False,
+        )
+        tools = [ctx.executable.plugin]
+    arguments += ["--objc_out=" + dir_out]
+
+    arguments += ["--proto_path=."]
+    arguments += get_include_protoc_args(protos)
+    # Include the output directory so that protoc puts the generated code in the
+    # right directory.
+    arguments += ["--proto_path={}".format(dir_out)]
+    arguments += ["--proto_path={}".format(_get_directory_from_proto(proto)) for proto in protos]
+    arguments += [_get_full_path_from_file(proto) for proto in protos]
+
+    # create a list of well known proto files if the argument is non-None
+    well_known_proto_files = []
+    if ctx.attr.use_well_known_protos:
+        f = ctx.attr.well_known_protos.files.to_list()[0].dirname
+        # go two levels up so that #import "google/protobuf/..." is correct
+        arguments += ["-I{0}".format(f + "/../..")] 
+        well_known_proto_files = ctx.attr.well_known_protos.files.to_list()
+    ctx.actions.run(
+        inputs = protos + well_known_proto_files,
+        tools = tools,
+        outputs = out_files,
+        executable = ctx.executable._protoc,
+        arguments = arguments,
+    )
+
+    return struct(files = depset(out_files))
+
+def _label_to_full_file_path(src, package):
+    if not src.startswith("//"):
+        # Relative from current package
+        if not src.startswith(":"):
+            # "a.proto" -> ":a.proto"
+            src = ":" + src
+        src = "//" + package + src
+    # Converts //path/to/package:File.ext to path/to/package/File.ext.
+    src = src.replace("//", "")
+    src = src.replace(":", "/")
+    if src.startswith("/"):
+        # "//:a.proto" -> "/a.proto" so remove the initial slash
+        return src[1:]
+    else:
+        return src
+
+def _get_output_file_name_from_proto(proto, fmt):
+    return proto_path_to_generated_filename(
+        _GENERATED_PROTOS_DIR + "/" +
+        _get_directory_from_proto(proto) + _get_slash_or_null_from_proto(proto) +
+        to_upper_camel_with_extension(_get_file_name_from_proto(proto), "proto"),
+        fmt,
+    )
+
+def _get_file_name_from_proto(proto):
+    return proto.path.rpartition("/")[2]
+
+def _get_slash_or_null_from_proto(proto):
+    """Potentially returns empty (if the file is in the root directory)"""
+    return proto.path.rpartition("/")[1]
+
+def _get_directory_from_proto(proto):
+    return proto.path.rpartition("/")[0]
+
+def _get_full_path_from_file(file):
+    gen_dir_length = 0
+    # if file is generated, then prepare to remote its root 
+    # (including CPU architecture...)
+    if not file.is_source:
+        gen_dir_length = len(file.root.path) + 1
+
+    return file.path[gen_dir_length:]
+
+def _join_directories(directories):
+    massaged_directories = [directory for directory in directories if len(directory) != 0]
+    return "/".join(massaged_directories)
+
+
+generate_objc = rule(
+    attrs = {
+        "deps": attr.label_list(
+            mandatory = True,
+            allow_empty = False,
+            providers = [ProtoInfo],
+        ),
+        "plugin": attr.label(
+            default = "@com_github_grpc_grpc//src/compiler:grpc_objective_c_plugin",
+            executable = True,
+            providers = ["files_to_run"],
+            cfg = "host",
+        ),
+        "srcs": attr.string_list(
+            mandatory = False,
+            allow_empty = True
+        ),
+        "use_well_known_protos": attr.bool(
+            mandatory = False,
+            default = False
+        ),
+        "well_known_protos": attr.label(
+            default = "@com_google_protobuf//:well_known_protos"
+        ),
+        "_protoc": attr.label(
+            default = Label("//external:protocol_compiler"),
+            executable = True,
+            cfg = "host",
+        ),
+    },
+    output_to_genfiles = True,
+    implementation = _generate_objc_impl
+)
+
+def _group_objc_files_impl(ctx):
+    suffix = ""
+    if ctx.attr.gen_mode == _GENERATE_HDRS:
+        suffix = "h"
+    elif ctx.attr.gen_mode == _GENERATE_SRCS:
+        suffix = "pbrpc.m"
+    elif ctx.attr.gen_mode == _GENERATE_NON_ARC_SRCS:
+        suffix = "pbobjc.m"
+    else:
+        fail("Undefined gen_mode")
+    out_files = [
+        file 
+        for file in ctx.attr.src.files.to_list() 
+        if file.basename.endswith(suffix)
+    ]
+    return struct(files = depset(out_files))
+
+generate_objc_hdrs = rule(
+    attrs = {
+        "src": attr.label(
+            mandatory = True,
+        ),
+        "gen_mode": attr.int(
+            default = _GENERATE_HDRS,
+        )
+    },
+    implementation = _group_objc_files_impl
+)
+
+generate_objc_srcs = rule(
+    attrs = {
+        "src": attr.label(
+            mandatory = True,
+        ),
+        "gen_mode": attr.int(
+            default = _GENERATE_SRCS,
+        )
+    },
+    implementation = _group_objc_files_impl
+)
+
+generate_objc_non_arc_srcs = rule(
+    attrs = {
+        "src": attr.label(
+            mandatory = True,
+        ),
+        "gen_mode": attr.int(
+            default = _GENERATE_NON_ARC_SRCS,
+        )
+    },
+    implementation = _group_objc_files_impl
+)

bazel/grpc_build_system.bzl

@@ -24,6 +24,7 @@
 #
 
 load("//bazel:cc_grpc_library.bzl", "cc_grpc_library")
+load("@build_bazel_rules_apple//apple:resources.bzl", "apple_resource_bundle")
 load("@upb//bazel:upb_proto_library.bzl", "upb_proto_library")
 
 # The set of pollers to test against if a test exercises polling
@@ -198,6 +199,19 @@ def grpc_cc_binary(name, srcs = [], deps = [], external_deps = [], args = [], da
     )
 
 def grpc_generate_one_off_targets():
+    apple_resource_bundle(
+        # The choice of name is signicant here, since it determines the bundle name.
+        name = "gRPCCertificates",
+        resources = ["etc/roots.pem"],
+    )
+
+    # In open-source, grpc_objc* libraries depend directly on //:grpc
+    native.alias(
+        name = "grpc_objc",
+        actual = "//:grpc",
+    )
+
+def grpc_objc_use_cronet_config():
     pass
 
 def grpc_sh_test(name, srcs, args = [], data = []):
@@ -240,6 +254,42 @@ def grpc_package(name, visibility = "private", features = []):
             features = features,
         )
 
+def grpc_objc_library(
+        name,
+        srcs,
+        hdrs = [],
+        textual_hdrs = [],
+        data = [],
+        deps = [],
+        defines = [],
+        includes = [],
+        visibility = ["//visibility:public"]):
+    """The grpc version of objc_library, only used for the Objective-C library compilation
+
+    Args:
+        name: name of target
+        hdrs: public headers
+        srcs: all source files (.m)
+        textual_hdrs: private headers
+        data: any other bundle resources
+        defines: preprocessors
+        includes: added to search path, always [the path to objc directory]
+        deps: dependencies
+        visibility: visibility, default to public
+    """
+    
+    native.objc_library(
+        name = name,
+        hdrs = hdrs,
+        srcs = srcs,
+        textual_hdrs = textual_hdrs,
+        data = data,
+        deps = deps,
+        defines = defines,
+        includes = includes,
+        visibility = visibility,
+    )
+    
 def grpc_upb_proto_library(name, deps):
     upb_proto_library(name = name, deps = deps)
 

bazel/grpc_deps.bzl

@@ -224,6 +224,14 @@ def grpc_deps():
             urls = ["https://github.com/bazelbuild/rules_go/releases/download/0.18.5/rules_go-0.18.5.tar.gz"],
             sha256 = "a82a352bffae6bee4e95f68a8d80a70e87f42c4741e6a448bec11998fcc82329",
         )
+
+    if "build_bazel_rules_apple" not in native.existing_rules():
+        git_repository(
+            name = "build_bazel_rules_apple",
+            remote = "https://github.com/bazelbuild/rules_apple.git",
+            tag = "0.17.2",
+        )
+    
 # TODO: move some dependencies from "grpc_deps" here?
 def grpc_test_only_deps():
     """Internal, not intended for use by packages that are consuming grpc.

bazel/grpc_util.bzl

@@ -0,0 +1,46 @@
+# Follows convention set in objectivec_helpers.cc in the protobuf ObjC compiler.
+_upper_segments_list = ["url", "http", "https"]
+
+def strip_extension(str):
+    return str.rpartition(".")[0]
+
+def capitalize(word):
+    if word in _upper_segments_list:
+        return word.upper()
+    else:
+        return word.capitalize()
+
+def lower_underscore_to_upper_camel(str):
+    str = strip_extension(str)
+    camel_case_str = ""
+    word = ""
+    for c in str.elems():  # NB: assumes ASCII!
+        if c.isalpha():
+            word += c.lower()
+        else:
+            # Last word is finished.
+            if len(word):
+                camel_case_str += capitalize(word)
+                word = ""
+            if c.isdigit():
+                camel_case_str += c
+
+            # Otherwise, drop the character. See UnderscoresToCamelCase in:
+            # third_party/protobuf/src/google/protobuf/compiler/objectivec/objectivec_helpers.cc
+
+    if len(word):
+        camel_case_str += capitalize(word)
+    return camel_case_str
+
+def file_to_upper_camel(src):
+    elements = src.rpartition("/")
+    upper_camel = lower_underscore_to_upper_camel(elements[-1])
+    return "".join(list(elements[:-1]) + [upper_camel])
+
+def file_with_extension(src, ext):
+    elements = src.rpartition("/")
+    return "".join(list(elements[:-1]) + [elements[-1], "." + ext])
+
+def to_upper_camel_with_extension(src, ext):
+    src = file_to_upper_camel(src)
+    return file_with_extension(src, ext)

bazel/objc_grpc_library.bzl

@@ -0,0 +1,68 @@
+load(
+    "//bazel:generate_objc.bzl",
+    "generate_objc",
+    "generate_objc_hdrs",
+    "generate_objc_srcs",
+    "generate_objc_non_arc_srcs"
+)
+load("//bazel:protobuf.bzl", "well_known_proto_libs")
+
+def objc_grpc_library(name, deps, srcs = [], use_well_known_protos = False, **kwargs):
+    """Generates messages and/or service stubs for given proto_library and all transitively dependent proto files
+
+    Args:
+        name: name of target
+        deps: a list of proto_library targets that needs to be compiled
+        srcs: a list of labels to proto files with service stubs to be generated,
+            labels specified must include service stubs; otherwise Bazel will complain about srcs being empty
+        use_well_known_protos: whether to use the well known protos defined in
+            @com_google_protobuf//src/google/protobuf, default to false
+        **kwargs: other arguments
+    """
+    objc_grpc_library_name = "_" + name + "_objc_grpc_library"
+
+    generate_objc(
+        name = objc_grpc_library_name,
+        srcs = srcs,
+        deps = deps,
+        use_well_known_protos = use_well_known_protos,
+        **kwargs
+    )
+
+    generate_objc_hdrs(
+        name = objc_grpc_library_name + "_hdrs",
+        src = ":" + objc_grpc_library_name,
+    )
+
+    generate_objc_non_arc_srcs(
+        name = objc_grpc_library_name + "_non_arc_srcs",
+        src = ":" + objc_grpc_library_name,
+    )
+
+    arc_srcs = None
+    if len(srcs) > 0:
+        generate_objc_srcs(
+            name = objc_grpc_library_name + "_srcs",
+            src = ":" + objc_grpc_library_name,
+        )
+        arc_srcs = [":" + objc_grpc_library_name + "_srcs"]
+
+    native.objc_library(
+        name = name,
+        hdrs = [":" + objc_grpc_library_name + "_hdrs"],
+        non_arc_srcs = [":" + objc_grpc_library_name + "_non_arc_srcs"],
+        srcs = arc_srcs,
+        defines = [
+            "GPB_USE_PROTOBUF_FRAMEWORK_IMPORTS=0",
+            "GPB_GRPC_FORWARD_DECLARE_MESSAGE_PROTO=0",
+        ],
+        includes = [
+            "_generated_protos",
+            "src/objective-c",
+        ],
+        deps = [
+            "@com_github_grpc_grpc//src/objective-c:proto_objc_rpc",
+            "@com_google_protobuf//:protobuf_objc",
+        ],
+    )
+

src/core/ext/filters/client_channel/client_channel.cc

@@ -1510,7 +1510,7 @@ void ChannelData::CreateResolvingLoadBalancingPolicyLocked() {
       UniquePtr<LoadBalancingPolicy::ChannelControlHelper>(
           New<ClientChannelControlHelper>(this));
   lb_args.args = channel_args_;
-  UniquePtr<char> target_uri(strdup(target_uri_.get()));
+  UniquePtr<char> target_uri(gpr_strdup(target_uri_.get()));
   resolving_lb_policy_.reset(New<ResolvingLoadBalancingPolicy>(
       std::move(lb_args), &grpc_client_channel_routing_trace,
       std::move(target_uri), ProcessResolverResultLocked, this));

src/objective-c/BUILD

@@ -0,0 +1,96 @@
+# gRPC Bazel BUILD file.
+#
+# Copyright 2019 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+licenses(["notice"])  # Apache v2
+
+package(default_visibility = ["//visibility:public"])
+
+load("//bazel:grpc_build_system.bzl", "grpc_objc_library", "grpc_objc_use_cronet_config")
+
+exports_files(["LICENSE"])
+
+grpc_objc_use_cronet_config()
+
+grpc_objc_library(
+    name = "rx_library",
+    srcs = glob([
+        "RxLibrary/*.m",
+        "RxLibrary/transformations/*.m",
+    ]),
+    hdrs = glob([
+        "RxLibrary/*.h",
+        "RxLibrary/transformations/*.h",
+    ]),
+    includes = ["."],
+    deps = [":rx_library_private"],
+)
+
+grpc_objc_library(
+    name = "rx_library_private",
+    srcs = glob([
+        "RxLibrary/private/*.m",
+    ]),
+    textual_hdrs = glob([
+        "RxLibrary/private/*.h",
+    ]),
+    visibility = ["//visibility:private"],
+)
+
+grpc_objc_library(
+    name = "grpc_objc_client",
+    srcs = glob(
+        [
+            "GRPCClient/*.m",
+            "GRPCClient/private/*.m",
+        ],
+        exclude = ["GRPCClient/GRPCCall+GID.m"],
+    ),
+    hdrs = glob(
+        [
+            "GRPCClient/*.h",
+            "GRPCClient/internal/*.h",
+        ],
+        exclude = ["GRPCClient/GRPCCall+GID.h"],
+    ),
+    data = ["//:gRPCCertificates"],
+    includes = ["."],
+    textual_hdrs = glob([
+        "GRPCClient/private/*.h",
+    ]),
+    deps = [
+        ":rx_library",
+        "//:grpc_objc",
+    ],
+)
+
+grpc_objc_library(
+    name = "proto_objc_rpc",
+    srcs = glob(
+        ["ProtoRPC/*.m"],
+    ),
+    hdrs = glob(
+        ["ProtoRPC/*.h"],
+    ),
+    # Different from Cocoapods, do not import as if @com_google_protobuf//:protobuf_objc is a framework,
+    # use the real paths of @com_google_protobuf//:protobuf_objc instead
+    defines = ["GPB_USE_PROTOBUF_FRAMEWORK_IMPORTS=0"],
+    includes = ["src/objective-c"],
+    deps = [
+        ":grpc_objc_client",
+        ":rx_library",
+        "@com_google_protobuf//:protobuf_objc",
+    ],
+)

src/objective-c/examples/BUILD

@@ -0,0 +1,69 @@
+# gRPC Bazel BUILD file.
+#
+# Copyright 2019 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+load("@build_bazel_rules_apple//apple:ios.bzl", "ios_application")
+load(
+    "@com_github_grpc_grpc//bazel:objc_grpc_library.bzl",
+    "objc_grpc_library",
+)
+
+proto_library(
+    name = "messages_proto",
+    srcs = ["BazelBuildSamples/messages.proto"],
+    visibility = ["//visibility:public"],
+)
+
+objc_grpc_library(
+    name = "test_grpc_objc",
+    srcs = ["BazelBuildSamples/rmt/test.proto"],
+    use_well_known_protos = True,
+    deps = [
+        "//src/objective-c/examples/BazelBuildSamples/rmt:test_proto",
+    ],
+)
+
+# Proof that without this works without srcs
+objc_grpc_library(
+    name = "test_objc",
+    use_well_known_protos = True,
+    deps = [
+        "//src/objective-c/examples/BazelBuildSamples/rmt:test_proto",
+    ]
+)
+
+objc_library(
+    name = "ios-sample-lib",
+    srcs = glob(["BazelBuildSamples/ios-sample/ios-sample/**/*.m"]),
+    hdrs = glob(["BazelBuildSamples/ios-sample/ios-sample/**/*.h"]),
+    data = glob([
+        "BazelBuildSamples/ios-sample/ios-sample/Assets.xcassets/**/*",
+        "BazelBuildSamples/ios-sample/ios-sample/Base.lproj/**/*"
+    ]),
+    deps = [
+        ":test_grpc_objc",
+    ]
+)
+
+ios_application(
+    name = "ios-sample",
+    bundle_id = "com.google.ios-sample-objc-bazel",
+    families = ["iphone"],
+    minimum_os_version = "9.0",
+    infoplists = ["BazelBuildSamples/ios-sample/ios-sample/Info.plist"],
+    visibility = ["//visibility:public"],
+    deps = [":ios-sample-lib"],
+)

src/objective-c/examples/BazelBuildSamples/ios-sample/Podfile

@@ -0,0 +1,31 @@
+platform :ios, '8.0'
+
+install! 'cocoapods', :deterministic_uuids => false
+
+ROOT_DIR = '../../../../..'
+
+target 'ios-sample' do
+  pod 'gRPC-ProtoRPC', :path => ROOT_DIR
+  pod 'gRPC', :path => ROOT_DIR
+  pod 'gRPC-Core', :path => ROOT_DIR
+  pod 'gRPC-RxLibrary', :path => ROOT_DIR
+  pod 'RemoteTest', :path => "../../RemoteTestClient"
+  pod '!ProtoCompiler-gRPCPlugin', :path => "#{ROOT_DIR}/src/objective-c"
+end
+
+pre_install do |installer|
+  grpc_core_spec = installer.pod_targets.find{|t| t.name.start_with?('gRPC-Core')}.root_spec
+
+  src_root = "$(PODS_TARGET_SRCROOT)"
+  grpc_core_spec.pod_target_xcconfig = {
+    'GRPC_SRC_ROOT' => src_root,
+    'HEADER_SEARCH_PATHS' => '"$(inherited)" "$(GRPC_SRC_ROOT)/include"',
+    'USER_HEADER_SEARCH_PATHS' => '"$(GRPC_SRC_ROOT)"',
+    # If we don't set these two settings, `include/grpc/support/time.h` and
+    # `src/core/lib/gpr/string.h` shadow the system `<time.h>` and `<string.h>`, breaking the
+    # build.
+    'USE_HEADERMAP' => 'NO',
+    'ALWAYS_SEARCH_USER_PATHS' => 'NO',
+  }
+end
+

src/objective-c/examples/BazelBuildSamples/ios-sample/ios-sample.xcodeproj/project.pbxproj

@@ -0,0 +1,413 @@
+// !$*UTF8*$!
+{
+	archiveVersion = 1;
+	classes = {
+	};
+	objectVersion = 50;
+	objects = {
+
+/* Begin PBXBuildFile section */
+		AB433CC922D7E38000D579CC /* AppDelegate.m in Sources */ = {isa = PBXBuildFile; fileRef = AB433CC822D7E38000D579CC /* AppDelegate.m */; };
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+		AB433CD322D7E38100D579CC /* Base */ = {isa = PBXFileReference; lastKnownFileType = file.storyboard; name = Base; path = Base.lproj/LaunchScreen.storyboard; sourceTree = "<group>"; };
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+				ED11F6CDF54788FC7CFD87B1 /* libPods-ios-sample.a in Frameworks */,
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+			runOnlyForDeploymentPostprocessing = 0;
+		};
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+
+/* Begin PBXGroup section */
+		2A170580B60E92B1A65525D4 /* Pods */ = {
+			isa = PBXGroup;
+			children = (
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+				112D4595FA3E81552DA9E877 /* Pods-ios-sample.release.xcconfig */,
+			);
+			name = Pods;
+			path = Pods;
+			sourceTree = "<group>";
+		};
+		AB433CBB22D7E38000D579CC = {
+			isa = PBXGroup;
+			children = (
+				AB433CC622D7E38000D579CC /* ios-sample */,
+				AB433CC522D7E38000D579CC /* Products */,
+				2A170580B60E92B1A65525D4 /* Pods */,
+				FD148AE940967C50DB2C12CB /* Frameworks */,
+			);
+			sourceTree = "<group>";
+		};
+		AB433CC522D7E38000D579CC /* Products */ = {
+			isa = PBXGroup;
+			children = (
+				AB433CC422D7E38000D579CC /* ios-sample.app */,
+			);
+			name = Products;
+			sourceTree = "<group>";
+		};
+		AB433CC622D7E38000D579CC /* ios-sample */ = {
+			isa = PBXGroup;
+			children = (
+				AB433CC722D7E38000D579CC /* AppDelegate.h */,
+				AB433CC822D7E38000D579CC /* AppDelegate.m */,
+				AB433CCA22D7E38000D579CC /* ViewController.h */,
+				AB433CCB22D7E38000D579CC /* ViewController.m */,
+				AB433CCD22D7E38000D579CC /* Main.storyboard */,
+				AB433CD022D7E38100D579CC /* Assets.xcassets */,
+				AB433CD222D7E38100D579CC /* LaunchScreen.storyboard */,
+				AB433CD522D7E38100D579CC /* Info.plist */,
+				AB433CD622D7E38100D579CC /* main.m */,
+			);
+			path = "ios-sample";
+			sourceTree = "<group>";
+		};
+		FD148AE940967C50DB2C12CB /* Frameworks */ = {
+			isa = PBXGroup;
+			children = (
+				5AF80A181E30BD84FA56BE33 /* libPods-ios-sample.a */,
+			);
+			name = Frameworks;
+			sourceTree = "<group>";
+		};
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+
+/* Begin PBXNativeTarget section */
+		AB433CC322D7E38000D579CC /* ios-sample */ = {
+			isa = PBXNativeTarget;
+			buildConfigurationList = AB433CDA22D7E38100D579CC /* Build configuration list for PBXNativeTarget "ios-sample" */;
+			buildPhases = (
+				9DD34A50D448CD3F464D4A3C /* [CP] Check Pods Manifest.lock */,
+				AB433CC022D7E38000D579CC /* Sources */,
+				AB433CC122D7E38000D579CC /* Frameworks */,
+				AB433CC222D7E38000D579CC /* Resources */,
+				630985F7228D41528084692C /* [CP] Copy Pods Resources */,
+			);
+			buildRules = (
+			);
+			dependencies = (
+			);
+			name = "ios-sample";
+			productName = "ios-sample";
+			productReference = AB433CC422D7E38000D579CC /* ios-sample.app */;
+			productType = "com.apple.product-type.application";
+		};
+/* End PBXNativeTarget section */
+
+/* Begin PBXProject section */
+		AB433CBC22D7E38000D579CC /* Project object */ = {
+			isa = PBXProject;
+			attributes = {
+				LastUpgradeCheck = 1010;
+				ORGANIZATIONNAME = "Tony Lu";
+				TargetAttributes = {
+					AB433CC322D7E38000D579CC = {
+						CreatedOnToolsVersion = 10.1;
+					};
+				};
+			};
+			buildConfigurationList = AB433CBF22D7E38000D579CC /* Build configuration list for PBXProject "ios-sample" */;
+			compatibilityVersion = "Xcode 9.3";
+			developmentRegion = en;
+			hasScannedForEncodings = 0;
+			knownRegions = (
+				en,
+				Base,
+			);
+			mainGroup = AB433CBB22D7E38000D579CC;
+			productRefGroup = AB433CC522D7E38000D579CC /* Products */;
+			projectDirPath = "";
+			projectRoot = "";
+			targets = (
+				AB433CC322D7E38000D579CC /* ios-sample */,
+			);
+		};
+/* End PBXProject section */
+
+/* Begin PBXResourcesBuildPhase section */
+		AB433CC222D7E38000D579CC /* Resources */ = {
+			isa = PBXResourcesBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+				AB433CD422D7E38100D579CC /* LaunchScreen.storyboard in Resources */,
+				AB433CD122D7E38100D579CC /* Assets.xcassets in Resources */,
+				AB433CCF22D7E38000D579CC /* Main.storyboard in Resources */,
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+		};
+/* End PBXResourcesBuildPhase section */
+
+/* Begin PBXShellScriptBuildPhase section */
+		630985F7228D41528084692C /* [CP] Copy Pods Resources */ = {
+			isa = PBXShellScriptBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+			);
+			inputFileListPaths = (
+				"${PODS_ROOT}/Target Support Files/Pods-ios-sample/Pods-ios-sample-resources-${CONFIGURATION}-input-files.xcfilelist",
+			);
+			name = "[CP] Copy Pods Resources";
+			outputFileListPaths = (
+				"${PODS_ROOT}/Target Support Files/Pods-ios-sample/Pods-ios-sample-resources-${CONFIGURATION}-output-files.xcfilelist",
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+			shellPath = /bin/sh;
+			shellScript = "\"${PODS_ROOT}/Target Support Files/Pods-ios-sample/Pods-ios-sample-resources.sh\"\n";
+			showEnvVarsInLog = 0;
+		};
+		9DD34A50D448CD3F464D4A3C /* [CP] Check Pods Manifest.lock */ = {
+			isa = PBXShellScriptBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+			);
+			inputFileListPaths = (
+			);
+			inputPaths = (
+				"${PODS_PODFILE_DIR_PATH}/Podfile.lock",
+				"${PODS_ROOT}/Manifest.lock",
+			);
+			name = "[CP] Check Pods Manifest.lock";
+			outputFileListPaths = (
+			);
+			outputPaths = (
+				"$(DERIVED_FILE_DIR)/Pods-ios-sample-checkManifestLockResult.txt",
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+			shellPath = /bin/sh;
+			shellScript = "diff \"${PODS_PODFILE_DIR_PATH}/Podfile.lock\" \"${PODS_ROOT}/Manifest.lock\" > /dev/null\nif [ $? != 0 ] ; then\n    # print error to STDERR\n    echo \"error: The sandbox is not in sync with the Podfile.lock. Run 'pod install' or update your CocoaPods installation.\" >&2\n    exit 1\nfi\n# This output is used by Xcode 'outputs' to avoid re-running this script phase.\necho \"SUCCESS\" > \"${SCRIPT_OUTPUT_FILE_0}\"\n";
+			showEnvVarsInLog = 0;
+		};
+/* End PBXShellScriptBuildPhase section */
+
+/* Begin PBXSourcesBuildPhase section */
+		AB433CC022D7E38000D579CC /* Sources */ = {
+			isa = PBXSourcesBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+				AB433CCC22D7E38000D579CC /* ViewController.m in Sources */,
+				AB433CD722D7E38100D579CC /* main.m in Sources */,
+				AB433CC922D7E38000D579CC /* AppDelegate.m in Sources */,
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+		};
+/* End PBXSourcesBuildPhase section */
+
+/* Begin PBXVariantGroup section */
+		AB433CCD22D7E38000D579CC /* Main.storyboard */ = {
+			isa = PBXVariantGroup;
+			children = (
+				AB433CCE22D7E38000D579CC /* Base */,
+			);
+			name = Main.storyboard;
+			sourceTree = "<group>";
+		};
+		AB433CD222D7E38100D579CC /* LaunchScreen.storyboard */ = {
+			isa = PBXVariantGroup;
+			children = (
+				AB433CD322D7E38100D579CC /* Base */,
+			);
+			name = LaunchScreen.storyboard;
+			sourceTree = "<group>";
+		};
+/* End PBXVariantGroup section */
+
+/* Begin XCBuildConfiguration section */
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+			buildSettings = {
+				ALWAYS_SEARCH_USER_PATHS = NO;
+				CLANG_ANALYZER_NONNULL = YES;
+				CLANG_ANALYZER_NUMBER_OBJECT_CONVERSION = YES_AGGRESSIVE;
+				CLANG_CXX_LANGUAGE_STANDARD = "gnu++14";
+				CLANG_CXX_LIBRARY = "libc++";
+				CLANG_ENABLE_MODULES = YES;
+				CLANG_ENABLE_OBJC_ARC = YES;
+				CLANG_ENABLE_OBJC_WEAK = YES;
+				CLANG_WARN_BLOCK_CAPTURE_AUTORELEASING = YES;
+				CLANG_WARN_BOOL_CONVERSION = YES;
+				CLANG_WARN_COMMA = YES;
+				CLANG_WARN_CONSTANT_CONVERSION = YES;
+				CLANG_WARN_DEPRECATED_OBJC_IMPLEMENTATIONS = YES;
+				CLANG_WARN_DIRECT_OBJC_ISA_USAGE = YES_ERROR;
+				CLANG_WARN_DOCUMENTATION_COMMENTS = YES;
+				CLANG_WARN_EMPTY_BODY = YES;
+				CLANG_WARN_ENUM_CONVERSION = YES;
+				CLANG_WARN_INFINITE_RECURSION = YES;
+				CLANG_WARN_INT_CONVERSION = YES;
+				CLANG_WARN_NON_LITERAL_NULL_CONVERSION = YES;
+				CLANG_WARN_OBJC_IMPLICIT_RETAIN_SELF = YES;
+				CLANG_WARN_OBJC_LITERAL_CONVERSION = YES;
+				CLANG_WARN_OBJC_ROOT_CLASS = YES_ERROR;
+				CLANG_WARN_RANGE_LOOP_ANALYSIS = YES;
+				CLANG_WARN_STRICT_PROTOTYPES = YES;
+				CLANG_WARN_SUSPICIOUS_MOVE = YES;
+				CLANG_WARN_UNGUARDED_AVAILABILITY = YES_AGGRESSIVE;
+				CLANG_WARN_UNREACHABLE_CODE = YES;
+				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
+				CODE_SIGN_IDENTITY = "iPhone Developer";
+				COPY_PHASE_STRIP = NO;
+				DEBUG_INFORMATION_FORMAT = dwarf;
+				ENABLE_STRICT_OBJC_MSGSEND = YES;
+				ENABLE_TESTABILITY = YES;
+				GCC_C_LANGUAGE_STANDARD = gnu11;
+				GCC_DYNAMIC_NO_PIC = NO;
+				GCC_NO_COMMON_BLOCKS = YES;
+				GCC_OPTIMIZATION_LEVEL = 0;
+				GCC_PREPROCESSOR_DEFINITIONS = (
+					"DEBUG=1",
+					"$(inherited)",
+				);
+				GCC_WARN_64_TO_32_BIT_CONVERSION = YES;
+				GCC_WARN_ABOUT_RETURN_TYPE = YES_ERROR;
+				GCC_WARN_UNDECLARED_SELECTOR = YES;
+				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
+				GCC_WARN_UNUSED_FUNCTION = YES;
+				GCC_WARN_UNUSED_VARIABLE = YES;
+				IPHONEOS_DEPLOYMENT_TARGET = 12.1;
+				MTL_ENABLE_DEBUG_INFO = INCLUDE_SOURCE;
+				MTL_FAST_MATH = YES;
+				ONLY_ACTIVE_ARCH = YES;
+				SDKROOT = iphoneos;
+			};
+			name = Debug;
+		};
+		AB433CD922D7E38100D579CC /* Release */ = {
+			isa = XCBuildConfiguration;
+			buildSettings = {
+				ALWAYS_SEARCH_USER_PATHS = NO;
+				CLANG_ANALYZER_NONNULL = YES;
+				CLANG_ANALYZER_NUMBER_OBJECT_CONVERSION = YES_AGGRESSIVE;
+				CLANG_CXX_LANGUAGE_STANDARD = "gnu++14";
+				CLANG_CXX_LIBRARY = "libc++";
+				CLANG_ENABLE_MODULES = YES;
+				CLANG_ENABLE_OBJC_ARC = YES;
+				CLANG_ENABLE_OBJC_WEAK = YES;
+				CLANG_WARN_BLOCK_CAPTURE_AUTORELEASING = YES;
+				CLANG_WARN_BOOL_CONVERSION = YES;
+				CLANG_WARN_COMMA = YES;
+				CLANG_WARN_CONSTANT_CONVERSION = YES;
+				CLANG_WARN_DEPRECATED_OBJC_IMPLEMENTATIONS = YES;
+				CLANG_WARN_DIRECT_OBJC_ISA_USAGE = YES_ERROR;
+				CLANG_WARN_DOCUMENTATION_COMMENTS = YES;
+				CLANG_WARN_EMPTY_BODY = YES;
+				CLANG_WARN_ENUM_CONVERSION = YES;
+				CLANG_WARN_INFINITE_RECURSION = YES;
+				CLANG_WARN_INT_CONVERSION = YES;
+				CLANG_WARN_NON_LITERAL_NULL_CONVERSION = YES;
+				CLANG_WARN_OBJC_IMPLICIT_RETAIN_SELF = YES;
+				CLANG_WARN_OBJC_LITERAL_CONVERSION = YES;
+				CLANG_WARN_OBJC_ROOT_CLASS = YES_ERROR;
+				CLANG_WARN_RANGE_LOOP_ANALYSIS = YES;
+				CLANG_WARN_STRICT_PROTOTYPES = YES;
+				CLANG_WARN_SUSPICIOUS_MOVE = YES;
+				CLANG_WARN_UNGUARDED_AVAILABILITY = YES_AGGRESSIVE;
+				CLANG_WARN_UNREACHABLE_CODE = YES;
+				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
+				CODE_SIGN_IDENTITY = "iPhone Developer";
+				COPY_PHASE_STRIP = NO;
+				DEBUG_INFORMATION_FORMAT = "dwarf-with-dsym";
+				ENABLE_NS_ASSERTIONS = NO;
+				ENABLE_STRICT_OBJC_MSGSEND = YES;
+				GCC_C_LANGUAGE_STANDARD = gnu11;
+				GCC_NO_COMMON_BLOCKS = YES;
+				GCC_WARN_64_TO_32_BIT_CONVERSION = YES;
+				GCC_WARN_ABOUT_RETURN_TYPE = YES_ERROR;
+				GCC_WARN_UNDECLARED_SELECTOR = YES;
+				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
+				GCC_WARN_UNUSED_FUNCTION = YES;
+				GCC_WARN_UNUSED_VARIABLE = YES;
+				IPHONEOS_DEPLOYMENT_TARGET = 12.1;
+				MTL_ENABLE_DEBUG_INFO = NO;
+				MTL_FAST_MATH = YES;
+				SDKROOT = iphoneos;
+				VALIDATE_PRODUCT = YES;
+			};
+			name = Release;
+		};
+		AB433CDB22D7E38100D579CC /* Debug */ = {
+			isa = XCBuildConfiguration;
+			baseConfigurationReference = 72599BE4AC5785D3368D40DD /* Pods-ios-sample.debug.xcconfig */;
+			buildSettings = {
+				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
+				CODE_SIGN_STYLE = Automatic;
+				DEVELOPMENT_TEAM = 6T98ZJNPG5;
+				INFOPLIST_FILE = "ios-sample/Info.plist";
+				LD_RUNPATH_SEARCH_PATHS = (
+					"$(inherited)",
+					"@executable_path/Frameworks",
+				);
+				PRODUCT_BUNDLE_IDENTIFIER = "com.google.ios-sample-objc-bazel";
+				PRODUCT_NAME = "$(TARGET_NAME)";
+				TARGETED_DEVICE_FAMILY = "1,2";
+			};
+			name = Debug;
+		};
+		AB433CDC22D7E38100D579CC /* Release */ = {
+			isa = XCBuildConfiguration;
+			baseConfigurationReference = 112D4595FA3E81552DA9E877 /* Pods-ios-sample.release.xcconfig */;
+			buildSettings = {
+				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
+				CODE_SIGN_STYLE = Automatic;
+				DEVELOPMENT_TEAM = 6T98ZJNPG5;
+				INFOPLIST_FILE = "ios-sample/Info.plist";
+				LD_RUNPATH_SEARCH_PATHS = (
+					"$(inherited)",
+					"@executable_path/Frameworks",
+				);
+				PRODUCT_BUNDLE_IDENTIFIER = "com.google.ios-sample-objc-bazel";
+				PRODUCT_NAME = "$(TARGET_NAME)";
+				TARGETED_DEVICE_FAMILY = "1,2";
+			};
+			name = Release;
+		};
+/* End XCBuildConfiguration section */
+
+/* Begin XCConfigurationList section */
+		AB433CBF22D7E38000D579CC /* Build configuration list for PBXProject "ios-sample" */ = {
+			isa = XCConfigurationList;
+			buildConfigurations = (
+				AB433CD822D7E38100D579CC /* Debug */,
+				AB433CD922D7E38100D579CC /* Release */,
+			);
+			defaultConfigurationIsVisible = 0;
+			defaultConfigurationName = Release;
+		};
+		AB433CDA22D7E38100D579CC /* Build configuration list for PBXNativeTarget "ios-sample" */ = {
+			isa = XCConfigurationList;
+			buildConfigurations = (
+				AB433CDB22D7E38100D579CC /* Debug */,
+				AB433CDC22D7E38100D579CC /* Release */,
+			);
+			defaultConfigurationIsVisible = 0;
+			defaultConfigurationName = Release;
+		};
+/* End XCConfigurationList section */
+	};
+	rootObject = AB433CBC22D7E38000D579CC /* Project object */;
+}

src/objective-c/examples/BazelBuildSamples/ios-sample/ios-sample/AppDelegate.h

@@ -0,0 +1,25 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#import <UIKit/UIKit.h>
+
+@interface AppDelegate : UIResponder<UIApplicationDelegate>
+
+@property(strong, nonatomic) UIWindow* window;
+
+@end

src/objective-c/examples/BazelBuildSamples/ios-sample/ios-sample/AppDelegate.m

@@ -0,0 +1,63 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#import "AppDelegate.h"
+
+@interface AppDelegate ()
+
+@end
+
+@implementation AppDelegate
+
+- (BOOL)application:(UIApplication *)application
+    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
+  // Override point for customization after application launch.
+  return YES;
+}
+
+- (void)applicationWillResignActive:(UIApplication *)application {
+  // Sent when the application is about to move from active to inactive state. This can occur for
+  // certain types of temporary interruptions (such as an incoming phone call or SMS message) or
+  // when the user quits the application and it begins the transition to the background state. Use
+  // this method to pause ongoing tasks, disable timers, and invalidate graphics rendering
+  // callbacks. Games should use this method to pause the game.
+}
+
+- (void)applicationDidEnterBackground:(UIApplication *)application {
+  // Use this method to release shared resources, save user data, invalidate timers, and store
+  // enough application state information to restore your application to its current state in case
+  // it is terminated later. If your application supports background execution, this method is
+  // called instead of applicationWillTerminate: when the user quits.
+}
+
+- (void)applicationWillEnterForeground:(UIApplication *)application {
+  // Called as part of the transition from the background to the active state; here you can undo
+  // many of the changes made on entering the background.
+}
+
+- (void)applicationDidBecomeActive:(UIApplication *)application {
+  // Restart any tasks that were paused (or not yet started) while the application was inactive. If
+  // the application was previously in the background, optionally refresh the user interface.
+}
+
+- (void)applicationWillTerminate:(UIApplication *)application {
+  // Called when the application is about to terminate. Save data if appropriate. See also
+  // applicationDidEnterBackground:.
+}
+
+@end

src/objective-c/examples/BazelBuildSamples/ios-sample/ios-sample/Assets.xcassets/AppIcon.appiconset/Contents.json

@@ -0,0 +1,98 @@
+{
+  "images" : [
+    {
+      "idiom" : "iphone",
+      "size" : "20x20",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "20x20",
+      "scale" : "3x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "29x29",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "29x29",
+      "scale" : "3x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "40x40",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "40x40",
+      "scale" : "3x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "60x60",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "60x60",
+      "scale" : "3x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "20x20",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "20x20",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "29x29",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "29x29",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "40x40",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "40x40",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "76x76",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "76x76",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "83.5x83.5",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "ios-marketing",
+      "size" : "1024x1024",
+      "scale" : "1x"
+    }
+  ],
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  }
+}

src/objective-c/examples/BazelBuildSamples/ios-sample/ios-sample/Assets.xcassets/Contents.json

@@ -0,0 +1,6 @@
+{
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  }
+}

src/objective-c/examples/BazelBuildSamples/ios-sample/ios-sample/Base.lproj/LaunchScreen.storyboard

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="13122.16" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" launchScreen="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="01J-lp-oVM">
+    <dependencies>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="13104.12"/>
+        <capability name="Safe area layout guides" minToolsVersion="9.0"/>
+        <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
+    </dependencies>
+    <scenes>
+        <!--View Controller-->
+        <scene sceneID="EHf-IW-A2E">
+            <objects>
+                <viewController id="01J-lp-oVM" sceneMemberID="viewController">
+                    <view key="view" contentMode="scaleToFill" id="Ze5-6b-2t3">
+                        <rect key="frame" x="0.0" y="0.0" width="375" height="667"/>
+                        <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                        <color key="backgroundColor" red="1" green="1" blue="1" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+                        <viewLayoutGuide key="safeArea" id="6Tk-OE-BBY"/>
+                    </view>
+                </viewController>
+                <placeholder placeholderIdentifier="IBFirstResponder" id="iYj-Kq-Ea1" userLabel="First Responder" sceneMemberID="firstResponder"/>
+            </objects>
+            <point key="canvasLocation" x="53" y="375"/>
+        </scene>
+    </scenes>
+</document>

src/objective-c/examples/BazelBuildSamples/ios-sample/ios-sample/Base.lproj/Main.storyboard

@@ -0,0 +1,38 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="14460.31" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="BYZ-38-t0r">
+    <device id="retina4_7" orientation="portrait">
+        <adaptation id="fullscreen"/>
+    </device>
+    <dependencies>
+        <deployment identifier="iOS"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="14460.20"/>
+        <capability name="Safe area layout guides" minToolsVersion="9.0"/>
+        <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
+    </dependencies>
+    <scenes>
+        <!--View Controller-->
+        <scene sceneID="tne-QT-ifu">
+            <objects>
+                <viewController id="BYZ-38-t0r" customClass="ViewController" sceneMemberID="viewController">
+                    <view key="view" contentMode="scaleToFill" id="8bC-Xf-vdC">
+                        <rect key="frame" x="0.0" y="0.0" width="375" height="667"/>
+                        <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                        <subviews>
+                            <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="iTL-zv-YSZ">
+                                <rect key="frame" x="164" y="318" width="46" height="30"/>
+                                <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
+                                <state key="normal" title="Button"/>
+                                <connections>
+                                    <action selector="tapCall:" destination="BYZ-38-t0r" eventType="touchUpInside" id="c5c-m5-SGC"/>
+                                </connections>
+                            </button>
+                        </subviews>
+                        <color key="backgroundColor" red="1" green="1" blue="1" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+                        <viewLayoutGuide key="safeArea" id="6Tk-OE-BBY"/>
+                    </view>
+                </viewController>
+                <placeholder placeholderIdentifier="IBFirstResponder" id="dkx-z0-nzr" sceneMemberID="firstResponder"/>
+            </objects>
+        </scene>
+    </scenes>
+</document>

src/objective-c/examples/BazelBuildSamples/ios-sample/ios-sample/Info.plist

@@ -0,0 +1,45 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>CFBundleDevelopmentRegion</key>
+	<string>en_US</string>
+	<key>CFBundleExecutable</key>
+	<string>$(EXECUTABLE_NAME)</string>
+	<key>CFBundleIdentifier</key>
+	<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
+	<key>CFBundleInfoDictionaryVersion</key>
+	<string>6.0</string>
+	<key>CFBundleName</key>
+	<string>$(PRODUCT_NAME)</string>
+	<key>CFBundlePackageType</key>
+	<string>APPL</string>
+	<key>CFBundleShortVersionString</key>
+	<string>1.0</string>
+	<key>CFBundleVersion</key>
+	<string>1</string>
+	<key>LSRequiresIPhoneOS</key>
+	<true/>
+	<key>UILaunchStoryboardName</key>
+	<string>LaunchScreen</string>
+	<key>UIMainStoryboardFile</key>
+	<string>Main</string>
+	<key>UIRequiredDeviceCapabilities</key>
+	<array>
+		<string>armv7</string>
+	</array>
+	<key>UISupportedInterfaceOrientations</key>
+	<array>
+		<string>UIInterfaceOrientationPortrait</string>
+		<string>UIInterfaceOrientationLandscapeLeft</string>
+		<string>UIInterfaceOrientationLandscapeRight</string>
+	</array>
+	<key>UISupportedInterfaceOrientations~ipad</key>
+	<array>
+		<string>UIInterfaceOrientationPortrait</string>
+		<string>UIInterfaceOrientationPortraitUpsideDown</string>
+		<string>UIInterfaceOrientationLandscapeLeft</string>
+		<string>UIInterfaceOrientationLandscapeRight</string>
+	</array>
+</dict>
+</plist>

src/objective-c/examples/BazelBuildSamples/ios-sample/ios-sample/ViewController.h

@@ -0,0 +1,23 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#import <UIKit/UIKit.h>
+
+@interface ViewController : UIViewController
+
+@end

src/objective-c/examples/BazelBuildSamples/ios-sample/ios-sample/ViewController.m

@@ -0,0 +1,86 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#import "ViewController.h"
+
+#import <GRPCClient/GRPCCall.h>
+#if COCOAPODS
+#import <RemoteTest/Messages.pbobjc.h>
+#import <RemoteTest/Test.pbrpc.h>
+#else
+#import "src/objective-c/examples/BazelBuildSamples/Messages.pbobjc.h"
+#import "src/objective-c/examples/BazelBuildSamples/rmt/Test.pbrpc.h"
+#endif
+
+static NSString *const kPackage = @"grpc.testing";
+static NSString *const kService = @"TestService";
+
+@interface ViewController ()<GRPCResponseHandler>
+
+@end
+
+@implementation ViewController {
+  GRPCCallOptions *_options;
+}
+
+- (void)viewDidLoad {
+  [super viewDidLoad];
+
+  GRPCMutableCallOptions *options = [[GRPCMutableCallOptions alloc] init];
+  // optionally modify options
+  _options = options;
+}
+
+- (IBAction)tapCall:(id)sender {
+  GRPCProtoMethod *kUnaryCallMethod =
+      [[GRPCProtoMethod alloc] initWithPackage:kPackage service:kService method:@"UnaryCall"];
+
+  GRPCRequestOptions *requestOptions =
+      [[GRPCRequestOptions alloc] initWithHost:@"grpc-test.sandbox.googleapis.com"
+                                          path:kUnaryCallMethod.HTTPPath
+                                        safety:GRPCCallSafetyCacheableRequest];
+
+  GRPCCall2 *call = [[GRPCCall2 alloc] initWithRequestOptions:requestOptions
+                                              responseHandler:self
+                                                  callOptions:_options];
+
+  RMTSimpleRequest *request = [RMTSimpleRequest message];
+  request.responseSize = 100;
+
+  [call start];
+  [call writeData:[request data]];
+  [call finish];
+}
+
+- (dispatch_queue_t)dispatchQueue {
+  return dispatch_get_main_queue();
+}
+
+- (void)didReceiveInitialMetadata:(NSDictionary *)initialMetadata {
+  NSLog(@"Header: %@", initialMetadata);
+}
+
+- (void)didReceiveData:(id)data {
+  NSLog(@"Message: %@", data);
+}
+
+- (void)didCloseWithTrailingMetadata:(NSDictionary *)trailingMetadata error:(NSError *)error {
+  NSLog(@"Trailer: %@\nError: %@", trailingMetadata, error);
+}
+
+@end

src/objective-c/examples/BazelBuildSamples/ios-sample/ios-sample/main.m

@@ -0,0 +1,26 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#import <UIKit/UIKit.h>
+#import "AppDelegate.h"
+
+int main(int argc, char* argv[]) {
+  @autoreleasepool {
+    return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
+  }
+}

src/objective-c/examples/BazelBuildSamples/messages.proto

@@ -0,0 +1,118 @@
+// Copyright 2015 gRPC authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Message definitions to be used by integration test service definitions.
+
+syntax = "proto3";
+
+package grpc.testing;
+
+option objc_class_prefix = "RMT";
+
+// The type of payload that should be returned.
+enum PayloadType {
+  // Compressable text format.
+  COMPRESSABLE = 0;
+
+  // Uncompressable binary format.
+  UNCOMPRESSABLE = 1;
+
+  // Randomly chosen from all other formats defined in this enum.
+  RANDOM = 2;
+}
+
+// A block of data, to simply increase gRPC message size.
+message Payload {
+  // The type of data in body.
+  PayloadType type = 1;
+  // Primary contents of payload.
+  bytes body = 2;
+}
+
+// Unary request.
+message SimpleRequest {
+  // Desired payload type in the response from the server.
+  // If response_type is RANDOM, server randomly chooses one from other formats.
+  PayloadType response_type = 1;
+
+  // Desired payload size in the response from the server.
+  // If response_type is COMPRESSABLE, this denotes the size before compression.
+  int32 response_size = 2;
+
+  // Optional input payload sent along with the request.
+  Payload payload = 3;
+
+  // Whether SimpleResponse should include username.
+  bool fill_username = 4;
+
+  // Whether SimpleResponse should include OAuth scope.
+  bool fill_oauth_scope = 5;
+}
+
+// Unary response, as configured by the request.
+message SimpleResponse {
+  // Payload to increase message size.
+  Payload payload = 1;
+  // The user the request came from, for verifying authentication was
+  // successful when the client expected it.
+  string username = 2;
+  // OAuth scope.
+  string oauth_scope = 3;
+}
+
+// Client-streaming request.
+message StreamingInputCallRequest {
+  // Optional input payload sent along with the request.
+  Payload payload = 1;
+
+  // Not expecting any payload from the response.
+}
+
+// Client-streaming response.
+message StreamingInputCallResponse {
+  // Aggregated size of payloads received from the client.
+  int32 aggregated_payload_size = 1;
+}
+
+// Configuration for a particular response.
+message ResponseParameters {
+  // Desired payload sizes in responses from the server.
+  // If response_type is COMPRESSABLE, this denotes the size before compression.
+  int32 size = 1;
+
+  // Desired interval between consecutive responses in the response stream in
+  // microseconds.
+  int32 interval_us = 2;
+}
+
+// Server-streaming request.
+message StreamingOutputCallRequest {
+  // Desired payload type in the response from the server.
+  // If response_type is RANDOM, the payload from each response in the stream
+  // might be of different types. This is to simulate a mixed type of payload
+  // stream.
+  PayloadType response_type = 1;
+
+  // Configuration for each expected response message.
+  repeated ResponseParameters response_parameters = 2;
+
+  // Optional input payload sent along with the request.
+  Payload payload = 3;
+}
+
+// Server-streaming response, as configured by the request and parameters.
+message StreamingOutputCallResponse {
+  // Payload to increase response size.
+  Payload payload = 1;
+}

src/objective-c/examples/BazelBuildSamples/rmt/BUILD

@@ -0,0 +1,28 @@
+# gRPC Bazel BUILD file.
+#
+# Copyright 2019 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+licenses(["notice"])  # Apache v2
+
+package(default_visibility = ["//visibility:public"])
+
+exports_files(["LICENSE"])
+
+proto_library(
+    name = "test_proto",
+    srcs = ["test.proto"],
+    deps = ["//src/objective-c/examples:messages_proto"],
+    visibility = ["//visibility:public"],
+)

src/objective-c/examples/BazelBuildSamples/rmt/test.proto

@@ -0,0 +1,57 @@
+// Copyright 2015 gRPC authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// An integration test service that covers all the method signature permutations
+// of unary/streaming requests/responses.
+syntax = "proto3";
+
+import "google/protobuf/empty.proto";
+import "src/objective-c/examples/BazelBuildSamples/messages.proto";
+
+package grpc.testing;
+
+option objc_class_prefix = "RMT";
+
+// A simple service to test the various types of RPCs and experiment with
+// performance with various types of payload.
+service TestService {
+  // One empty request followed by one empty response.
+  rpc EmptyCall(google.protobuf.Empty) returns (google.protobuf.Empty);
+
+  // One request followed by one response.
+  rpc UnaryCall(SimpleRequest) returns (SimpleResponse);
+
+  // One request followed by a sequence of responses (streamed download).
+  // The server returns the payload with client desired type and sizes.
+  rpc StreamingOutputCall(StreamingOutputCallRequest)
+      returns (stream StreamingOutputCallResponse);
+
+  // A sequence of requests followed by one response (streamed upload).
+  // The server returns the aggregated size of client payload as the result.
+  rpc StreamingInputCall(stream StreamingInputCallRequest)
+      returns (StreamingInputCallResponse);
+
+  // A sequence of requests with each request served by the server immediately.
+  // As one request could lead to multiple responses, this interface
+  // demonstrates the idea of full duplexing.
+  rpc FullDuplexCall(stream StreamingOutputCallRequest)
+      returns (stream StreamingOutputCallResponse);
+
+  // A sequence of requests followed by a sequence of responses.
+  // The server buffers all the client requests and then serves them in order. A
+  // stream of responses are returned to the client when the server starts with
+  // first request.
+  rpc HalfDuplexCall(stream StreamingOutputCallRequest)
+      returns (stream StreamingOutputCallResponse);
+}

src/python/grpcio/grpc/_channel.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 """Invocation-side implementation of gRPC Python."""
 
+import functools
 import logging
 import sys
 import threading
@@ -81,17 +82,6 @@ def _unknown_code_details(unknown_cygrpc_code, details):
         unknown_cygrpc_code, details)
 
 
-def _wait_once_until(condition, until):
-    if until is None:
-        condition.wait()
-    else:
-        remaining = until - time.time()
-        if remaining < 0:
-            raise grpc.FutureTimeoutError()
-        else:
-            condition.wait(timeout=remaining)
-
-
 class _RPCState(object):
 
     def __init__(self, due, initial_metadata, trailing_metadata, code, details):
@@ -178,12 +168,11 @@ def _event_handler(state, response_deserializer):
 #pylint: disable=too-many-statements
 def _consume_request_iterator(request_iterator, state, call, request_serializer,
                               event_handler):
-    if cygrpc.is_fork_support_enabled():
-        condition_wait_timeout = 1.0
-    else:
-        condition_wait_timeout = None
+    """Consume a request iterator supplied by the user."""
 
     def consume_request_iterator():  # pylint: disable=too-many-branches
+        # Iterate over the request iterator until it is exhausted or an error
+        # condition is encountered.
         while True:
             return_from_user_request_generator_invoked = False
             try:
@@ -224,14 +213,19 @@ def _consume_request_iterator(request_iterator, state, call, request_serializer,
                             state.due.add(cygrpc.OperationType.send_message)
                         else:
                             return
-                        while True:
-                            state.condition.wait(condition_wait_timeout)
-                            cygrpc.block_if_fork_in_progress(state)
-                            if state.code is None:
-                                if cygrpc.OperationType.send_message not in state.due:
-                                    break
-                            else:
-                                return
+
+                        def _done():
+                            return (state.code is not None or
+                                    cygrpc.OperationType.send_message not in
+                                    state.due)
+
+                        _common.wait(
+                            state.condition.wait,
+                            _done,
+                            spin_cb=functools.partial(
+                                cygrpc.block_if_fork_in_progress, state))
+                        if state.code is not None:
+                            return
                 else:
                     return
         with state.condition:
@@ -281,13 +275,21 @@ class _Rendezvous(grpc.RpcError, grpc.Future, grpc.Call):  # pylint: disable=too
         with self._state.condition:
             return self._state.code is not None
 
+    def _is_complete(self):
+        return self._state.code is not None
+
     def result(self, timeout=None):
-        until = None if timeout is None else time.time() + timeout
+        """Returns the result of the computation or raises its exception.
+
+        See grpc.Future.result for the full API contract.
+        """
         with self._state.condition:
-            while True:
-                if self._state.code is None:
-                    _wait_once_until(self._state.condition, until)
-                elif self._state.code is grpc.StatusCode.OK:
+            timed_out = _common.wait(
+                self._state.condition.wait, self._is_complete, timeout=timeout)
+            if timed_out:
+                raise grpc.FutureTimeoutError()
+            else:
+                if self._state.code is grpc.StatusCode.OK:
                     return self._state.response
                 elif self._state.cancelled:
                     raise grpc.FutureCancelledError()
@@ -295,12 +297,17 @@ class _Rendezvous(grpc.RpcError, grpc.Future, grpc.Call):  # pylint: disable=too
                     raise self
 
     def exception(self, timeout=None):
-        until = None if timeout is None else time.time() + timeout
+        """Return the exception raised by the computation.
+
+        See grpc.Future.exception for the full API contract.
+        """
         with self._state.condition:
-            while True:
-                if self._state.code is None:
-                    _wait_once_until(self._state.condition, until)
-                elif self._state.code is grpc.StatusCode.OK:
+            timed_out = _common.wait(
+                self._state.condition.wait, self._is_complete, timeout=timeout)
+            if timed_out:
+                raise grpc.FutureTimeoutError()
+            else:
+                if self._state.code is grpc.StatusCode.OK:
                     return None
                 elif self._state.cancelled:
                     raise grpc.FutureCancelledError()
@@ -308,12 +315,17 @@ class _Rendezvous(grpc.RpcError, grpc.Future, grpc.Call):  # pylint: disable=too
                     return self
 
     def traceback(self, timeout=None):
-        until = None if timeout is None else time.time() + timeout
+        """Access the traceback of the exception raised by the computation.
+
+        See grpc.future.traceback for the full API contract.
+        """
         with self._state.condition:
-            while True:
-                if self._state.code is None:
-                    _wait_once_until(self._state.condition, until)
-                elif self._state.code is grpc.StatusCode.OK:
+            timed_out = _common.wait(
+                self._state.condition.wait, self._is_complete, timeout=timeout)
+            if timed_out:
+                raise grpc.FutureTimeoutError()
+            else:
+                if self._state.code is grpc.StatusCode.OK:
                     return None
                 elif self._state.cancelled:
                     raise grpc.FutureCancelledError()
@@ -345,17 +357,23 @@ class _Rendezvous(grpc.RpcError, grpc.Future, grpc.Call):  # pylint: disable=too
                 raise StopIteration()
             else:
                 raise self
-            while True:
-                self._state.condition.wait()
-                if self._state.response is not None:
-                    response = self._state.response
-                    self._state.response = None
-                    return response
-                elif cygrpc.OperationType.receive_message not in self._state.due:
-                    if self._state.code is grpc.StatusCode.OK:
-                        raise StopIteration()
-                    elif self._state.code is not None:
-                        raise self
+
+            def _response_ready():
+                return (
+                    self._state.response is not None or
+                    (cygrpc.OperationType.receive_message not in self._state.due
+                     and self._state.code is not None))
+
+            _common.wait(self._state.condition.wait, _response_ready)
+            if self._state.response is not None:
+                response = self._state.response
+                self._state.response = None
+                return response
+            elif cygrpc.OperationType.receive_message not in self._state.due:
+                if self._state.code is grpc.StatusCode.OK:
+                    raise StopIteration()
+                elif self._state.code is not None:
+                    raise self
 
     def __iter__(self):
         return self
@@ -386,32 +404,47 @@ class _Rendezvous(grpc.RpcError, grpc.Future, grpc.Call):  # pylint: disable=too
 
     def initial_metadata(self):
         with self._state.condition:
-            while self._state.initial_metadata is None:
-                self._state.condition.wait()
+
+            def _done():
+                return self._state.initial_metadata is not None
+
+            _common.wait(self._state.condition.wait, _done)
             return self._state.initial_metadata
 
     def trailing_metadata(self):
         with self._state.condition:
-            while self._state.trailing_metadata is None:
-                self._state.condition.wait()
+
+            def _done():
+                return self._state.trailing_metadata is not None
+
+            _common.wait(self._state.condition.wait, _done)
             return self._state.trailing_metadata
 
     def code(self):
         with self._state.condition:
-            while self._state.code is None:
-                self._state.condition.wait()
+
+            def _done():
+                return self._state.code is not None
+
+            _common.wait(self._state.condition.wait, _done)
             return self._state.code
 
     def details(self):
         with self._state.condition:
-            while self._state.details is None:
-                self._state.condition.wait()
+
+            def _done():
+                return self._state.details is not None
+
+            _common.wait(self._state.condition.wait, _done)
             return _common.decode(self._state.details)
 
     def debug_error_string(self):
         with self._state.condition:
-            while self._state.debug_error_string is None:
-                self._state.condition.wait()
+
+            def _done():
+                return self._state.debug_error_string is not None
+
+            _common.wait(self._state.condition.wait, _done)
             return _common.decode(self._state.debug_error_string)
 
     def _repr(self):

src/python/grpcio/grpc/_common.py

@@ -15,6 +15,7 @@
 
 import logging
 
+import time
 import six
 
 import grpc
@@ -60,6 +61,8 @@ STATUS_CODE_TO_CYGRPC_STATUS_CODE = {
         CYGRPC_STATUS_CODE_TO_STATUS_CODE)
 }
 
+MAXIMUM_WAIT_TIMEOUT = 0.1
+
 
 def encode(s):
     if isinstance(s, bytes):
@@ -96,3 +99,50 @@ def deserialize(serialized_message, deserializer):
 
 def fully_qualified_method(group, method):
     return '/{}/{}'.format(group, method)
+
+
+def _wait_once(wait_fn, timeout, spin_cb):
+    wait_fn(timeout=timeout)
+    if spin_cb is not None:
+        spin_cb()
+
+
+def wait(wait_fn, wait_complete_fn, timeout=None, spin_cb=None):
+    """Blocks waiting for an event without blocking the thread indefinitely.
+
+    See https://github.com/grpc/grpc/issues/19464 for full context. CPython's
+    `threading.Event.wait` and `threading.Condition.wait` methods, if invoked
+    without a timeout kwarg, may block the calling thread indefinitely. If the
+    call is made from the main thread, this means that signal handlers may not
+    run for an arbitrarily long period of time.
+
+    This wrapper calls the supplied wait function with an arbitrary short
+    timeout to ensure that no signal handler has to wait longer than
+    MAXIMUM_WAIT_TIMEOUT before executing.
+
+    Args:
+      wait_fn: A callable acceptable a single float-valued kwarg named
+        `timeout`. This function is expected to be one of `threading.Event.wait`
+        or `threading.Condition.wait`.
+      wait_complete_fn: A callable taking no arguments and returning a bool.
+        When this function returns true, it indicates that waiting should cease.
+      timeout: An optional float-valued number of seconds after which the wait
+        should cease.
+      spin_cb: An optional Callable taking no arguments and returning nothing.
+        This callback will be called on each iteration of the spin. This may be
+        used for, e.g. work related to forking.
+
+    Returns:
+      True if a timeout was supplied and it was reached. False otherwise.
+    """
+    if timeout is None:
+        while not wait_complete_fn():
+            _wait_once(wait_fn, MAXIMUM_WAIT_TIMEOUT, spin_cb)
+    else:
+        end = time.time() + timeout
+        while not wait_complete_fn():
+            remaining = min(end - time.time(), MAXIMUM_WAIT_TIMEOUT)
+            if remaining < 0:
+                return True
+            _wait_once(wait_fn, remaining, spin_cb)
+    return False

src/python/grpcio_tests/commands.py

@@ -145,6 +145,8 @@ class TestGevent(setuptools.Command):
         'unit._exit_test.ExitTest.test_in_flight_partial_unary_stream_call',
         'unit._exit_test.ExitTest.test_in_flight_partial_stream_unary_call',
         'unit._exit_test.ExitTest.test_in_flight_partial_stream_stream_call',
+        # TODO(https://github.com/grpc/grpc/issues/18980): Reenable.
+        'unit._signal_handling_test.SignalHandlingTest',
         'unit._metadata_flags_test',
         'health_check._health_servicer_test.HealthServicerTest.test_cancelled_watch_removed_from_watch_list',
         # TODO(https://github.com/grpc/grpc/issues/17330) enable these three tests

src/python/grpcio_tests/tests/tests.json

@@ -67,6 +67,7 @@
   "unit._server_ssl_cert_config_test.ServerSSLCertReloadTestWithoutClientAuth",
   "unit._server_test.ServerTest",
   "unit._session_cache_test.SSLSessionCacheTest",
+  "unit._signal_handling_test.SignalHandlingTest",
   "unit._version_test.VersionTest",
   "unit.beta._beta_features_test.BetaFeaturesTest",
   "unit.beta._beta_features_test.ContextManagementAndLifecycleTest",

src/python/grpcio_tests/tests/unit/BUILD.bazel

@@ -16,6 +16,7 @@ GRPCIO_TESTS_UNIT = [
     "_credentials_test.py",
     "_dns_resolver_test.py",
     "_empty_message_test.py",
+    "_error_message_encoding_test.py",
     "_exit_test.py",
     "_interceptor_test.py",
     "_invalid_metadata_test.py",
@@ -27,6 +28,7 @@ GRPCIO_TESTS_UNIT = [
     # "_reconnect_test.py",
     "_resource_exhausted_test.py",
     "_rpc_test.py",
+    "_signal_handling_test.py",
     # TODO(ghostwriternr): To be added later.
     # "_server_ssl_cert_config_test.py",
     "_server_test.py",
@@ -39,6 +41,11 @@ py_library(
     srcs = ["_tcp_proxy.py"],
 )
 
+py_library(
+    name = "_signal_client",
+    srcs = ["_signal_client.py"],
+)
+
 py_library(
     name = "resources",
     srcs = ["resources.py"],
@@ -87,6 +94,7 @@ py_library(
             ":_server_shutdown_scenarios",
             ":_from_grpc_import_star",
             ":_tcp_proxy",
+            ":_signal_client",
             "//src/python/grpcio_tests/tests/unit/framework/common",
             "//src/python/grpcio_tests/tests/testing",
             requirement('six'),

src/python/grpcio_tests/tests/unit/_signal_client.py

@@ -0,0 +1,84 @@
+# Copyright 2019 the gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Client for testing responsiveness to signals."""
+
+from __future__ import print_function
+
+import argparse
+import functools
+import logging
+import signal
+import sys
+
+import grpc
+
+SIGTERM_MESSAGE = "Handling sigterm!"
+
+UNARY_UNARY = "/test/Unary"
+UNARY_STREAM = "/test/ServerStreaming"
+
+_MESSAGE = b'\x00\x00\x00'
+
+_ASSERTION_MESSAGE = "Control flow should never reach here."
+
+# NOTE(gnossen): We use a global variable here so that the signal handler can be
+# installed before the RPC begins. If we do not do this, then we may receive the
+# SIGINT before the signal handler is installed. I'm not happy with per-process
+# global state, but the per-process global state that is signal handlers
+# somewhat forces my hand.
+per_process_rpc_future = None
+
+
+def handle_sigint(unused_signum, unused_frame):
+    print(SIGTERM_MESSAGE)
+    if per_process_rpc_future is not None:
+        per_process_rpc_future.cancel()
+    sys.stderr.flush()
+    sys.exit(0)
+
+
+def main_unary(server_target):
+    """Initiate a unary RPC to be interrupted by a SIGINT."""
+    global per_process_rpc_future  # pylint: disable=global-statement
+    with grpc.insecure_channel(server_target) as channel:
+        multicallable = channel.unary_unary(UNARY_UNARY)
+        signal.signal(signal.SIGINT, handle_sigint)
+        per_process_rpc_future = multicallable.future(
+            _MESSAGE, wait_for_ready=True)
+        result = per_process_rpc_future.result()
+        assert False, _ASSERTION_MESSAGE
+
+
+def main_streaming(server_target):
+    """Initiate a streaming RPC to be interrupted by a SIGINT."""
+    global per_process_rpc_future  # pylint: disable=global-statement
+    with grpc.insecure_channel(server_target) as channel:
+        signal.signal(signal.SIGINT, handle_sigint)
+        per_process_rpc_future = channel.unary_stream(UNARY_STREAM)(
+            _MESSAGE, wait_for_ready=True)
+        for result in per_process_rpc_future:
+            pass
+        assert False, _ASSERTION_MESSAGE
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(description='Signal test client.')
+    parser.add_argument('server', help='Server target')
+    parser.add_argument(
+        'arity', help='RPC arity', choices=('unary', 'streaming'))
+    args = parser.parse_args()
+    if args.arity == 'unary':
+        main_unary(args.server)
+    else:
+        main_streaming(args.server)

src/python/grpcio_tests/tests/unit/_signal_handling_test.py

@@ -0,0 +1,172 @@
+# Copyright 2019 the gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Test of responsiveness to signals."""
+
+import logging
+import os
+import signal
+import subprocess
+import tempfile
+import threading
+import unittest
+import sys
+
+import grpc
+
+from tests.unit import test_common
+from tests.unit import _signal_client
+
+_CLIENT_PATH = None
+if sys.executable is not None:
+    _CLIENT_PATH = os.path.abspath(os.path.realpath(_signal_client.__file__))
+else:
+    # NOTE(rbellevi): For compatibility with internal testing.
+    if len(sys.argv) != 2:
+        raise RuntimeError("Must supply path to executable client.")
+    client_name = sys.argv[1].split("/")[-1]
+    del sys.argv[1]  # For compatibility with test runner.
+    _CLIENT_PATH = os.path.realpath(
+        os.path.join(os.path.dirname(os.path.abspath(__file__)), client_name))
+
+_HOST = 'localhost'
+
+
+class _GenericHandler(grpc.GenericRpcHandler):
+
+    def __init__(self):
+        self._connected_clients_lock = threading.RLock()
+        self._connected_clients_event = threading.Event()
+        self._connected_clients = 0
+
+        self._unary_unary_handler = grpc.unary_unary_rpc_method_handler(
+            self._handle_unary_unary)
+        self._unary_stream_handler = grpc.unary_stream_rpc_method_handler(
+            self._handle_unary_stream)
+
+    def _on_client_connect(self):
+        with self._connected_clients_lock:
+            self._connected_clients += 1
+            self._connected_clients_event.set()
+
+    def _on_client_disconnect(self):
+        with self._connected_clients_lock:
+            self._connected_clients -= 1
+            if self._connected_clients == 0:
+                self._connected_clients_event.clear()
+
+    def await_connected_client(self):
+        """Blocks until a client connects to the server."""
+        self._connected_clients_event.wait()
+
+    def _handle_unary_unary(self, request, servicer_context):
+        """Handles a unary RPC.
+
+        Blocks until the client disconnects and then echoes.
+        """
+        stop_event = threading.Event()
+
+        def on_rpc_end():
+            self._on_client_disconnect()
+            stop_event.set()
+
+        servicer_context.add_callback(on_rpc_end)
+        self._on_client_connect()
+        stop_event.wait()
+        return request
+
+    def _handle_unary_stream(self, request, servicer_context):
+        """Handles a server streaming RPC.
+
+        Blocks until the client disconnects and then echoes.
+        """
+        stop_event = threading.Event()
+
+        def on_rpc_end():
+            self._on_client_disconnect()
+            stop_event.set()
+
+        servicer_context.add_callback(on_rpc_end)
+        self._on_client_connect()
+        stop_event.wait()
+        yield request
+
+    def service(self, handler_call_details):
+        if handler_call_details.method == _signal_client.UNARY_UNARY:
+            return self._unary_unary_handler
+        elif handler_call_details.method == _signal_client.UNARY_STREAM:
+            return self._unary_stream_handler
+        else:
+            return None
+
+
+def _read_stream(stream):
+    stream.seek(0)
+    return stream.read()
+
+
+def _start_client(args, stdout, stderr):
+    invocation = None
+    if sys.executable is not None:
+        invocation = (sys.executable, _CLIENT_PATH) + tuple(args)
+    else:
+        invocation = (_CLIENT_PATH,) + tuple(args)
+    return subprocess.Popen(invocation, stdout=stdout, stderr=stderr)
+
+
+class SignalHandlingTest(unittest.TestCase):
+
+    def setUp(self):
+        self._server = test_common.test_server()
+        self._port = self._server.add_insecure_port('{}:0'.format(_HOST))
+        self._handler = _GenericHandler()
+        self._server.add_generic_rpc_handlers((self._handler,))
+        self._server.start()
+
+    def tearDown(self):
+        self._server.stop(None)
+
+    @unittest.skipIf(os.name == 'nt', 'SIGINT not supported on windows')
+    def testUnary(self):
+        """Tests that the server unary code path does not stall signal handlers."""
+        server_target = '{}:{}'.format(_HOST, self._port)
+        with tempfile.TemporaryFile(mode='r') as client_stdout:
+            with tempfile.TemporaryFile(mode='r') as client_stderr:
+                client = _start_client((server_target, 'unary'), client_stdout,
+                                       client_stderr)
+                self._handler.await_connected_client()
+                client.send_signal(signal.SIGINT)
+                self.assertFalse(client.wait(), msg=_read_stream(client_stderr))
+                client_stdout.seek(0)
+                self.assertIn(_signal_client.SIGTERM_MESSAGE,
+                              client_stdout.read())
+
+    @unittest.skipIf(os.name == 'nt', 'SIGINT not supported on windows')
+    def testStreaming(self):
+        """Tests that the server streaming code path does not stall signal handlers."""
+        server_target = '{}:{}'.format(_HOST, self._port)
+        with tempfile.TemporaryFile(mode='r') as client_stdout:
+            with tempfile.TemporaryFile(mode='r') as client_stderr:
+                client = _start_client((server_target, 'streaming'),
+                                       client_stdout, client_stderr)
+                self._handler.await_connected_client()
+                client.send_signal(signal.SIGINT)
+                self.assertFalse(client.wait(), msg=_read_stream(client_stderr))
+                client_stdout.seek(0)
+                self.assertIn(_signal_client.SIGTERM_MESSAGE,
+                              client_stdout.read())
+
+
+if __name__ == '__main__':
+    logging.basicConfig()
+    unittest.main(verbosity=2)

tools/run_tests/sanity/check_bazel_workspace.py

@@ -63,6 +63,7 @@ _GRPC_DEP_NAMES = [
     _ZOPEFOUNDATION_ZOPE_INTERFACE_DEP_NAME,
     _TWISTED_CONSTANTLY_DEP_NAME,
     'io_bazel_rules_go',
+    'build_bazel_rules_apple',
 ]
 
 _GRPC_BAZEL_ONLY_DEPS = [
@@ -76,6 +77,7 @@ _GRPC_BAZEL_ONLY_DEPS = [
     _ZOPEFOUNDATION_ZOPE_INTERFACE_DEP_NAME,
     _TWISTED_CONSTANTLY_DEP_NAME,
     'io_bazel_rules_go',
+    'build_bazel_rules_apple',
 ]
 
 
@@ -106,6 +108,13 @@ class BazelEvalState(object):
             return
         self.names_and_urls[args['name']] = args['url']
 
+    def git_repository(self, **args):
+        assert self.names_and_urls.get(args['name']) is None
+        if args['name'] in _GRPC_BAZEL_ONLY_DEPS:
+            self.names_and_urls[args['name']] = 'dont care'
+            return
+        self.names_and_urls[args['name']] = args['remote']
+
 
 # Parse git hashes from bazel/grpc_deps.bzl {new_}http_archive rules
 with open(os.path.join('bazel', 'grpc_deps.bzl'), 'r') as f:
@@ -121,6 +130,7 @@ build_rules = {
     'native': eval_state,
     'http_archive': lambda **args: eval_state.http_archive(**args),
     'load': lambda a, b: None,
+    'git_repository': lambda **args: eval_state.git_repository(**args),
 }
 exec bazel_file in build_rules
 for name in _GRPC_DEP_NAMES:
@@ -162,6 +172,7 @@ for name in _GRPC_DEP_NAMES:
         'native': state,
         'http_archive': lambda **args: state.http_archive(**args),
         'load': lambda a, b: None,
+        'git_repository': lambda **args: state.git_repository(**args),
     }
     exec bazel_file in rules
     assert name not in names_and_urls_with_overridden_name.keys()