1 /* Copyright 2017 The TensorFlow Authors. All Rights Reserved. 2 3 Licensed under the Apache License, Version 2.0 (the "License"); 4 you may not use this file except in compliance with the License. 5 You may obtain a copy of the License at 6 7 http://www.apache.org/licenses/LICENSE-2.0 8 9 Unless required by applicable law or agreed to in writing, software 10 distributed under the License is distributed on an "AS IS" BASIS, 11 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 See the License for the specific language governing permissions and 13 limitations under the License. 14 ==============================================================================*/ 15 16 #ifndef TENSORFLOW_COMPILER_XLA_POOL_H_ 17 #define TENSORFLOW_COMPILER_XLA_POOL_H_ 18 19 #include <functional> 20 #include <vector> 21 22 #include "tensorflow/compiler/xla/ptr_util.h" 23 #include "tensorflow/core/platform/mutex.h" 24 25 namespace xla { 26 27 // Pool of values, which are created as needed and destroyed when the `Pool` is 28 // destroyed 29 template <typename T> 30 class Pool { 31 public: 32 struct Deleter { 33 void operator()(T* ptr) { pool->Deallocate(ptr); } 34 35 Pool<T>* pool; 36 }; 37 38 // A pointer to a taken element of a `Pool` which returns it to the pool on 39 // destruction 40 using SmartPtr = std::unique_ptr<T, Deleter>; 41 42 // Constructs a `Pool` with given factory function, which need not be 43 // thread-safe. 44 explicit Pool(std::function<std::unique_ptr<T>()> factory) 45 : factory_(factory) {} 46 47 explicit Pool() : Pool([]() { return MakeUnique<T>(); }) {} 48 49 // Returns a pointer to a value in the pool, creating a new value if none is 50 // free. The returned smart pointer returns the element to the pool on 51 // destruction. 52 // 53 // This method is thread-safe. 54 SmartPtr Allocate() { 55 tensorflow::mutex_lock lock(mu_); 56 T* ptr; 57 if (!xs_.empty()) { 58 ptr = std::move(xs_.back()).release(); 59 xs_.pop_back(); 60 } else { 61 ptr = factory_().release(); 62 } 63 Deleter del = {this}; 64 return std::unique_ptr<T, Deleter>(ptr, del); 65 } 66 67 private: 68 // Puts a pointer to a value back into the pool, leaving it free for future 69 // use. 70 // 71 // This method is thread-safe. 72 void Deallocate(T* ptr) { 73 tensorflow::mutex_lock lock(mu_); 74 xs_.push_back(std::unique_ptr<T>(ptr)); 75 } 76 77 const std::function<std::unique_ptr<T>()> factory_ GUARDED_BY(mu_); 78 std::vector<std::unique_ptr<T>> xs_ GUARDED_BY(mu_); 79 tensorflow::mutex mu_; 80 }; 81 82 } // namespace xla 83 84 #endif // TENSORFLOW_COMPILER_XLA_POOL_H_ 85
