mirror of https://github.com/grpc/grpc.git
[logging] Add a helper to drop a list of variables out in a LOG statement (#36554)
Not the fastest implementation possible, but it's a log helper so I'm not particularly fussed either -- but a useful utility that we can iterate on later to help debugging.
Closes #36554
COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/36554 from ctiller:args 33b4802fcc
PiperOrigin-RevId: 632997320
pull/36592/head^2
Craig Tiller
7 months ago
committed by
Copybara-Service
parent
989268253e
commit
06b097691e
9 changed files with 280 additions and 3 deletions
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// Copyright 2024 gRPC authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "src/core/lib/gprpp/dump_args.h" |
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#include "absl/log/check.h" |
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#include "absl/strings/ascii.h" |
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#include "absl/strings/string_view.h" |
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namespace grpc_core { |
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namespace dump_args_detail { |
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std::ostream& operator<<(std::ostream& out, const DumpArgs& args) { |
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// Parse the argument string into a vector of keys.
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// #__VA_ARGS__ produces a stringified version of the arguments passed to the
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// macro. It's comma separated, and we can use that to split the string into
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// keys. Those keys might include parenthesis for e.g. argument lists, and so
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// we need to skip commas that are inside parenthesis.
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std::vector<absl::string_view> keys; |
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int depth = 0; |
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const char* start = args.arg_string_; |
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for (const char* p = args.arg_string_; *p; ++p) { |
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if (*p == '(') { |
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++depth; |
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} else if (*p == ')') { |
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--depth; |
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} else if (*p == ',' && depth == 0) { |
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keys.push_back(absl::string_view(start, p - start)); |
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start = p + 1; |
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} |
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} |
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keys.push_back(start); |
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CHECK_EQ(keys.size(), args.arg_dumpers_.size()); |
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for (size_t i = 0; i < keys.size(); i++) { |
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if (i != 0) out << ", "; |
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out << absl::StripAsciiWhitespace(keys[i]) << " = "; |
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args.arg_dumpers_[i](out); |
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} |
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return out; |
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} |
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} // namespace dump_args_detail
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} // namespace grpc_core
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// Copyright 2024 gRPC authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef GRPC_SRC_CORE_LIB_GPRPP_DUMP_ARGS_H |
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#define GRPC_SRC_CORE_LIB_GPRPP_DUMP_ARGS_H |
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#include <ostream> |
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#include <vector> |
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#include "absl/functional/any_invocable.h" |
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namespace grpc_core { |
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namespace dump_args_detail { |
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// Helper function... just ignore the initializer list passed into it.
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// Allows doing 'statements' via parameter pack expansion in C++11 - given
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// template <typename... Ts>:
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// do_these_things({foo<Ts>()...});
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// will execute foo<T>() for each T in Ts.
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template <typename T> |
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void do_these_things(std::initializer_list<T>) {} |
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class DumpArgs { |
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public: |
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template <typename... Args> |
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explicit DumpArgs(const char* arg_string, const Args&... args) |
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: arg_string_(arg_string) { |
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do_these_things( |
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{AddDumper([a = &args](std::ostream& os) { os << *a; })...}); |
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} |
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friend std::ostream& operator<<(std::ostream& out, const DumpArgs& args); |
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private: |
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int AddDumper(absl::AnyInvocable<void(std::ostream&) const> dumper) { |
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arg_dumpers_.push_back(std::move(dumper)); |
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return 0; |
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} |
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const char* arg_string_; |
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std::vector<absl::AnyInvocable<void(std::ostream&) const>> arg_dumpers_; |
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}; |
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} // namespace dump_args_detail
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} // namespace grpc_core
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// Helper to print a list of variables and their values.
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// Each type must be streamable to std::ostream.
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// Usage:
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// int a = 1;
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// int b = 2;
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// LOG(INFO) << GRPC_DUMP_ARGS(a, b)
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// Output:
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// a = 1, b = 2
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#define GRPC_DUMP_ARGS(...) \ |
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grpc_core::dump_args_detail::DumpArgs(#__VA_ARGS__, __VA_ARGS__) |
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#endif // GRPC_SRC_CORE_LIB_GPRPP_DUMP_ARGS_H
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// Copyright 2024 gRPC authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "src/core/lib/gprpp/dump_args.h" |
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#include <sstream> |
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#include "gtest/gtest.h" |
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template <typename T> |
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std::string Stringify(const T& t) { |
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std::ostringstream oss; |
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oss << t; |
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return oss.str(); |
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} |
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int add(int a, int b) { return a + b; } |
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TEST(DumpArgsTest, Basic) { |
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int a = 1; |
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int b = 2; |
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int c = 3; |
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EXPECT_EQ("a = 1, b = 2, c = 3", Stringify(GRPC_DUMP_ARGS(a, b, c))); |
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} |
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TEST(DumpArgsTest, FunctionCall) { |
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EXPECT_EQ("add(1, 2) = 3", Stringify(GRPC_DUMP_ARGS(add(1, 2)))); |
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} |
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int main(int argc, char** argv) { |
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::testing::InitGoogleTest(&argc, argv); |
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return RUN_ALL_TESTS(); |
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} |
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