mirror of https://github.com/grpc/grpc.git
Promise library context management helpers (#26912)
* Promise library context management helpers * Automated change: Fix sanity tests * Automated change: Fix sanity tests * fixes * Automated change: Fix sanity tests * missing file * Automated change: Fix sanity tests * compatibility * build * Automated change: Fix sanity tests * propagate * Automated change: Fix sanity tests * merge with head * Automated change: Fix sanity tests Co-authored-by: ctiller <ctiller@users.noreply.github.com>pull/27073/head
Craig Tiller
3 years ago
committed by
GitHub
parent
4744aceb68
commit
aacd32c721
9 changed files with 229 additions and 9 deletions
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// Copyright 2021 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_CORE_LIB_PROMISE_CONTEXT_H |
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#define GRPC_CORE_LIB_PROMISE_CONTEXT_H |
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#include <grpc/impl/codegen/port_platform.h> |
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#include <utility> |
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#include "src/core/lib/gpr/tls.h" |
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namespace grpc_core { |
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// To avoid accidentally creating context types, we require an explicit
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// specialization of this template per context type. The specialization need
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// not contain any members, only exist.
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// The reason for avoiding this is that context types each use a thread local.
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template <typename T> |
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struct ContextType; |
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namespace promise_detail { |
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template <typename T> |
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class Context : public ContextType<T> { |
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public: |
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explicit Context(T* p) : old_(current_) { current_ = p; } |
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~Context() { current_ = old_; } |
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Context(const Context&) = delete; |
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Context& operator=(const Context&) = delete; |
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static T* get() { return current_; } |
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private: |
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T* const old_; |
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static GPR_THREAD_LOCAL(T*) current_; |
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}; |
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template <typename T> |
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GPR_THREAD_LOCAL(T*) |
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Context<T>::current_; |
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template <typename T, typename F> |
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class WithContext { |
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public: |
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WithContext(F f, T* context) : context_(context), f_(std::move(f)) {} |
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decltype(std::declval<F>()()) operator()() { |
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Context<T> ctx(context_); |
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return f_(); |
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} |
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private: |
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T* context_; |
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F f_; |
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}; |
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} // namespace promise_detail
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// Retrieve the current value of a context.
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template <typename T> |
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T* GetContext() { |
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return promise_detail::Context<T>::get(); |
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} |
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// Given a promise and a context, return a promise that has that context set.
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template <typename T, typename F> |
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promise_detail::WithContext<T, F> WithContext(F f, T* context) { |
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return promise_detail::WithContext<T, F>(f, context); |
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} |
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} // namespace grpc_core
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#endif // GRPC_CORE_LIB_PROMISE_CONTEXT_H
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// Copyright 2021 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/promise/context.h" |
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#include <gtest/gtest.h> |
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namespace grpc_core { |
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struct TestContext { |
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bool done = false; |
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}; |
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template <> |
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struct ContextType<TestContext> {}; |
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TEST(Context, WithContext) { |
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EXPECT_EQ(GetContext<TestContext>(), nullptr); |
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TestContext test; |
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EXPECT_EQ(GetContext<TestContext>(), nullptr); |
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EXPECT_EQ(test.done, false); |
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WithContext([]() { GetContext<TestContext>()->done = true; }, &test)(); |
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EXPECT_EQ(test.done, true); |
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} |
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} // namespace grpc_core
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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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