Single set pointer (#29114)
* Single set pointer * Update single_set_ptr.h * fix * fix * build * custom deleterspull/29125/head^2
Craig Tiller
3 years ago
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7 changed files with 384 additions and 0 deletions
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// Copyright 2022 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_GPRPP_SINGLE_SET_PTR_H |
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#define GRPC_CORE_LIB_GPRPP_SINGLE_SET_PTR_H |
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#include <grpc/support/port_platform.h> |
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#include <atomic> |
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#include <memory> |
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#include <grpc/support/log.h> |
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namespace grpc_core { |
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template <class T, class Deleter = std::default_delete<T>> |
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class SingleSetPtr { |
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public: |
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SingleSetPtr() = default; |
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~SingleSetPtr() { Delete(p_.load(std::memory_order_relaxed)); } |
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SingleSetPtr(const SingleSetPtr&) = delete; |
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SingleSetPtr& operator=(const SingleSetPtr&) = delete; |
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SingleSetPtr(SingleSetPtr&& other) noexcept |
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: p_(other.p_.exchange(sentinel())) {} |
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SingleSetPtr& operator=(SingleSetPtr&& other) noexcept { |
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Set(other.p_.exchange(sentinel(), std::memory_order_acq_rel)); |
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return *this; |
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} |
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// Set the pointer;
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// if already set, return the pre-set value and delete ptr;
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// if deleted, return nullptr and delete ptr.
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T* Set(T* ptr) { |
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T* expected = nullptr; |
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if (!p_.compare_exchange_strong(expected, ptr, std::memory_order_acq_rel, |
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std::memory_order_acquire)) { |
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Delete(ptr); |
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return expected == sentinel() ? nullptr : expected; |
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} |
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return ptr; |
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} |
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// Clear the pointer. Cannot be set again.
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void Reset() { Delete(p_.exchange(sentinel(), std::memory_order_acq_rel)); } |
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bool is_set() const { |
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T* p = p_.load(std::memory_order_acquire); |
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return p != nullptr && p != sentinel(); |
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} |
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T* operator->() const { |
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T* p = p_.load(std::memory_order_acquire); |
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GPR_DEBUG_ASSERT(p != sentinel()); |
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GPR_DEBUG_ASSERT(p != nullptr); |
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return p; |
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} |
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T& operator*() const { return *operator->(); } |
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private: |
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static T* sentinel() { return reinterpret_cast<T*>(1); } |
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static void Delete(T* p) { |
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if (p == sentinel() || p == nullptr) return; |
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Deleter()(p); |
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} |
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std::atomic<T*> p_{nullptr}; |
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}; |
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} // namespace grpc_core
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#endif // GRPC_CORE_LIB_GPRPP_SINGLE_SET_PTR_H
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@ -0,0 +1,63 @@ |
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// Copyright 2022 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/single_set_ptr.h" |
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#include <thread> |
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#include <gtest/gtest.h> |
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namespace grpc_core { |
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namespace testing { |
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TEST(SingleSetPtrTest, NoOp) { SingleSetPtr<int>(); } |
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TEST(SingleSetPtrTest, CanSet) { |
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SingleSetPtr<int> p; |
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EXPECT_FALSE(p.is_set()); |
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EXPECT_DEATH_IF_SUPPORTED(gpr_log(GPR_ERROR, "%d", *p), ""); |
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p.Set(new int(42)); |
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EXPECT_EQ(*p, 42); |
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} |
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TEST(SingleSetPtrTest, CanReset) { |
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SingleSetPtr<int> p; |
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EXPECT_FALSE(p.is_set()); |
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p.Set(new int(42)); |
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EXPECT_TRUE(p.is_set()); |
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p.Set(new int(43)); |
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EXPECT_EQ(*p, 42); |
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p.Reset(); |
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EXPECT_FALSE(p.is_set()); |
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} |
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TEST(SingleSetPtrTest, LotsOfSetters) { |
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SingleSetPtr<int> p; |
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std::vector<std::thread> threads; |
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threads.reserve(100); |
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for (int i = 0; i < 100; i++) { |
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threads.emplace_back([&p, i]() { p.Set(new int(i)); }); |
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} |
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for (auto& t : threads) { |
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t.join(); |
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} |
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} |
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} // namespace testing
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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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