Add a utility to capture arguments by move even in C++11 (#26923)

* Add a utility to capture arguments by move even in C++11

* add test

* Automated change: Fix sanity tests

* missing file

* Automated change: Fix sanity tests

* better test

* Automated change: Fix sanity tests

* fmt

Co-authored-by: ctiller <ctiller@users.noreply.github.com>

BUILD

@@ -712,6 +712,14 @@ grpc_cc_library(
     ],
 )
 
+grpc_cc_library(
+    name = "capture",
+    external_deps = ["absl/utility"],
+    language = "c++",
+    public_hdrs = ["src/core/lib/gprpp/capture.h"],
+    deps = ["gpr_platform"],
+)
+
 grpc_cc_library(
     name = "construct_destruct",
     language = "c++",

CMakeLists.txt

@@ -817,6 +817,7 @@ if(gRPC_BUILD_TESTS)
   add_dependencies(buildtests_cxx byte_buffer_test)
   add_dependencies(buildtests_cxx byte_stream_test)
   add_dependencies(buildtests_cxx cancel_ares_query_test)
+  add_dependencies(buildtests_cxx capture_test)
   add_dependencies(buildtests_cxx cel_authorization_engine_test)
   add_dependencies(buildtests_cxx certificate_provider_registry_test)
   add_dependencies(buildtests_cxx certificate_provider_store_test)
@@ -9287,6 +9288,41 @@ target_link_libraries(cancel_ares_query_test
 )
 
 
+endif()
+if(gRPC_BUILD_TESTS)
+
+add_executable(capture_test
+  test/core/gprpp/capture_test.cc
+  third_party/googletest/googletest/src/gtest-all.cc
+  third_party/googletest/googlemock/src/gmock-all.cc
+)
+
+target_include_directories(capture_test
+  PRIVATE
+    ${CMAKE_CURRENT_SOURCE_DIR}
+    ${CMAKE_CURRENT_SOURCE_DIR}/include
+    ${_gRPC_ADDRESS_SORTING_INCLUDE_DIR}
+    ${_gRPC_RE2_INCLUDE_DIR}
+    ${_gRPC_SSL_INCLUDE_DIR}
+    ${_gRPC_UPB_GENERATED_DIR}
+    ${_gRPC_UPB_GRPC_GENERATED_DIR}
+    ${_gRPC_UPB_INCLUDE_DIR}
+    ${_gRPC_XXHASH_INCLUDE_DIR}
+    ${_gRPC_ZLIB_INCLUDE_DIR}
+    third_party/googletest/googletest/include
+    third_party/googletest/googletest
+    third_party/googletest/googlemock/include
+    third_party/googletest/googlemock
+    ${_gRPC_PROTO_GENS_DIR}
+)
+
+target_link_libraries(capture_test
+  ${_gRPC_PROTOBUF_LIBRARIES}
+  ${_gRPC_ALLTARGETS_LIBRARIES}
+  absl::utility
+)
+
+
 endif()
 if(gRPC_BUILD_TESTS)
 

build_autogenerated.yaml

@@ -4778,6 +4778,17 @@ targets:
   deps:
   - grpc++_test_config
   - grpc++_test_util
+- name: capture_test
+  gtest: true
+  build: test
+  language: c++
+  headers:
+  - src/core/lib/gprpp/capture.h
+  src:
+  - test/core/gprpp/capture_test.cc
+  deps:
+  - absl/utility:utility
+  uses_polling: false
 - name: cel_authorization_engine_test
   gtest: true
   build: test

src/core/lib/gprpp/capture.h

@@ -0,0 +1,75 @@
+// Copyright 2021 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.
+
+#ifndef GRPC_CORE_LIB_GPRPP_CAPTURE_H
+#define GRPC_CORE_LIB_GPRPP_CAPTURE_H
+
+#include <grpc/impl/codegen/port_platform.h>
+
+#include <tuple>
+#include <utility>
+#include "absl/utility/utility.h"
+
+namespace grpc_core {
+
+namespace detail {
+
+template <typename F, typename... Captures>
+class Capture {
+ public:
+  explicit Capture(F f, Captures... captures)
+      : f_(std::move(f)), captures_(std::move(captures)...) {}
+
+  template <typename... Args>
+  decltype(std::declval<F>()(static_cast<Captures*>(nullptr)...,
+                             std::declval<Args>()...))
+  operator()(Args... args) {
+    auto f = &f_;
+    return absl::apply(
+        [f, &args...](Captures&... captures) {
+          return (*f)(&captures..., std::move(args)...);
+        },
+        captures_);
+  }
+
+ private:
+  GPR_NO_UNIQUE_ADDRESS F f_;
+  GPR_NO_UNIQUE_ADDRESS std::tuple<Captures...> captures_;
+};
+
+}  // namespace detail
+
+// C++11 helper - best explained by usage:
+//
+// BigThing big_thing;
+// auto f = Capture(
+//             [](BigThing* c, int a, int b) { /*...*/ },
+//             std::move(big_thing));
+//
+// results in: f being a callable that takes arguments (int a, int b), and
+// captures the original value of big_thing by move. Each call, a pointer to
+// each captured thing is inserted into the argument list at the beginning so it
+// can be manipulated.
+//
+// Captured values are mutable, and it's the users responsibility to ensure,
+// should this callable be invoked from different threads, that proper locking
+// is implemented.
+template <typename F, typename... Captures>
+detail::Capture<F, Captures...> Capture(F f, Captures... captures) {
+  return detail::Capture<F, Captures...>(std::move(f), std::move(captures)...);
+}
+
+}  // namespace grpc_core
+
+#endif  // GRPC_CORE_LIB_GPRPP_CAPTURE_H

test/core/gprpp/BUILD

@@ -271,3 +271,15 @@ grpc_cc_test(
         "//test/core/util:grpc_test_util",
     ],
 )
+
+grpc_cc_test(
+    name = "capture_test",
+    srcs = ["capture_test.cc"],
+    external_deps = ["gtest"],
+    language = "c++",
+    uses_polling = False,
+    deps = [
+        "//:capture",
+        "//test/core/util:grpc_suppressions",
+    ],
+)

test/core/gprpp/capture_test.cc

@@ -0,0 +1,38 @@
+// Copyright 2021 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.
+
+#include "src/core/lib/gprpp/capture.h"
+#include <gtest/gtest.h>
+
+namespace grpc_core {
+
+TEST(CaptureTest, Capture) {
+  auto f = Capture([](int* p) { EXPECT_EQ(*p, 42); }, 42);
+  f();
+}
+
+TEST(CaptureTest, WithArgsAndReturn) {
+  int captured = 1;
+  auto f =
+      Capture([captured](int* p, int arg) { return (captured + *p) * arg; }, 2);
+  EXPECT_EQ(f(2), 6);
+  EXPECT_EQ(f(3), 9);
+}
+
+}  // namespace grpc_core
+
+int main(int argc, char** argv) {
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}

tools/run_tests/generated/tests.json

@@ -3889,6 +3889,30 @@
     ],
     "uses_polling": true
   },
+  {
+    "args": [],
+    "benchmark": false,
+    "ci_platforms": [
+      "linux",
+      "mac",
+      "posix",
+      "windows"
+    ],
+    "cpu_cost": 1.0,
+    "exclude_configs": [],
+    "exclude_iomgrs": [],
+    "flaky": false,
+    "gtest": true,
+    "language": "c++",
+    "name": "capture_test",
+    "platforms": [
+      "linux",
+      "mac",
+      "posix",
+      "windows"
+    ],
+    "uses_polling": false
+  },
   {
     "args": [],
     "benchmark": false,