Merge pull request #20918 from veblush/absl-flag

Add GRPC_USE_ABSL flag

BUILD

@@ -69,6 +69,11 @@ config_setting(
     values = {"cpu": "darwin"},
 )
 
+config_setting(
+    name = "grpc_use_absl",
+    values = {"define": "GRPC_USE_ABSL=1"},
+)
+
 python_config_settings()
 
 # This should be updated along with build.yaml

bazel/grpc_build_system.bzl

@@ -59,6 +59,8 @@ def _get_external_deps(external_deps):
             })
         elif dep == "cronet_c_for_grpc":
             ret += ["//third_party/objective_c/Cronet:cronet_c_for_grpc"]
+        elif dep.startswith("absl/"):
+            ret += ["@com_google_absl//" + dep]
         else:
             ret += ["//external:" + dep]
     return ret
@@ -86,6 +88,19 @@ def grpc_cc_library(
     linkopts = if_not_windows(["-pthread"])
     if use_cfstream:
         linkopts = linkopts + if_mac(["-framework CoreFoundation"])
+
+    # This is a temporary solution to enable absl dependency only for
+    # Bazel-build with grpc_use_absl enabled to abseilfy in-house classes
+    # such as inlined_vector before absl is fully supported.
+    # When https://github.com/grpc/grpc/pull/20184 is merged, it will
+    # be removed.
+    more_external_deps = []
+    if name == "inlined_vector":
+        more_external_deps += select({
+            "//:grpc_use_absl": ["@com_google_absl//absl/container:inlined_vector"],
+            "//conditions:default": [],
+        })
+
     native.cc_library(
         name = name,
         srcs = srcs,
@@ -101,9 +116,13 @@ def grpc_cc_library(
                       "//:grpc_allow_exceptions": ["GRPC_ALLOW_EXCEPTIONS=1"],
                       "//:grpc_disallow_exceptions": ["GRPC_ALLOW_EXCEPTIONS=0"],
                       "//conditions:default": [],
+                  }) +
+                  select({
+                      "//:grpc_use_absl": ["GRPC_USE_ABSL=1"],
+                      "//conditions:default": [],
                   }),
         hdrs = hdrs + public_hdrs,
-        deps = deps + _get_external_deps(external_deps),
+        deps = deps + _get_external_deps(external_deps) + more_external_deps,
         copts = copts,
         visibility = visibility,
         testonly = testonly,

include/grpc/impl/codegen/port_platform.h

@@ -27,6 +27,13 @@
  *  - some syscalls to be made directly
  */
 
+/*
+ * Defines GRPC_USE_ABSL to use Abseil Common Libraries (C++)
+ */
+#ifndef GRPC_USE_ABSL
+#define GRPC_USE_ABSL 0
+#endif
+
 /* Get windows.h included everywhere (we need it) */
 #if defined(_WIN64) || defined(WIN64) || defined(_WIN32) || defined(WIN32)
 #ifndef WIN32_LEAN_AND_MEAN

src/core/lib/gprpp/inlined_vector.h

@@ -26,8 +26,19 @@
 
 #include "src/core/lib/gprpp/memory.h"
 
+#if GRPC_USE_ABSL
+#include "absl/container/inlined_vector.h"
+#endif
+
 namespace grpc_core {
 
+#if GRPC_USE_ABSL
+
+template <typename T, size_t N, typename A = std::allocator<T>>
+using InlinedVector = absl::InlinedVector<T, N, A>;
+
+#else
+
 // NOTE: We eventually want to use absl::InlinedVector here.  However,
 // there are currently build problems that prevent us from using absl.
 // In the interim, we define a custom implementation as a place-holder,
@@ -228,6 +239,8 @@ class InlinedVector {
   size_t capacity_;
 };
 
+#endif
+
 }  // namespace grpc_core
 
 #endif /* GRPC_CORE_LIB_GPRPP_INLINED_VECTOR_H */

tools/internal_ci/linux/grpc_bazel_build_in_docker.sh

@@ -25,3 +25,7 @@ git clone /var/local/jenkins/grpc /var/local/git/grpc
 ${name}')
 cd /var/local/git/grpc
 bazel build --spawn_strategy=standalone --genrule_strategy=standalone :all test/... examples/...
+
+# This is a temporary build test before full absl support is done
+# with https://github.com/grpc/grpc/pull/20918.
+bazel build --spawn_strategy=standalone --genrule_strategy=standalone --define=GRPC_USE_ABSL=1 :grpc