1 /* Copyright 2015 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_STREAM_EXECUTOR_EXECUTOR_CACHE_H_ 17 #define TENSORFLOW_STREAM_EXECUTOR_EXECUTOR_CACHE_H_ 18 19 #include <functional> 20 #include <map> 21 22 #include "absl/synchronization/mutex.h" 23 #include "tensorflow/stream_executor/lib/status.h" 24 #include "tensorflow/stream_executor/lib/statusor.h" 25 #include "tensorflow/stream_executor/stream_executor_pimpl.h" 26 27 namespace stream_executor { 28 29 // Utility class to allow Platform objects to manage cached StreamExecutors. 30 // Thread-safe. 31 class ExecutorCache { 32 public: ExecutorCache()33 ExecutorCache() {} 34 35 // Looks up 'config' in the cache. Returns a pointer to the existing executor, 36 // if already present, or creates it using 'factory', if it does not. 37 // Factories may be executed concurrently for different device ordinals. 38 typedef port::StatusOr<std::unique_ptr<StreamExecutor>> ExecutorFactory(); 39 port::StatusOr<StreamExecutor*> GetOrCreate( 40 const StreamExecutorConfig& config, 41 const std::function<ExecutorFactory>& factory); 42 43 // Returns a pointer to the described executor (if one with a matching config 44 // has been created), or a NOT_FOUND status. 45 port::StatusOr<StreamExecutor*> Get(const StreamExecutorConfig& config); 46 47 // Destroys all Executors and clears the cache. 48 // Performs no synchronization with the executors - undefined behavior may 49 // occur if any executors are active! 50 void DestroyAllExecutors(); 51 52 private: 53 // Each Entry contains zero or more cached executors for a device ordinal. 54 struct Entry { 55 ~Entry(); 56 57 // Mutex that guards the contents of each entry. The 'mutex_' of the 58 // ExecutorCache class protects both the 'cache_' and the existence of each 59 // Entry, but not the Entry's contents. 'configurations_mutex' protects the 60 // contents of the entry after 'mutex_' has been dropped. 61 absl::Mutex configurations_mutex; 62 63 // Vector of cached {config, executor} pairs. 64 std::vector< 65 std::pair<StreamExecutorConfig, std::unique_ptr<StreamExecutor>>> 66 configurations TF_GUARDED_BY(configurations_mutex); 67 }; 68 69 // Maps ordinal number to a list of cached executors for that ordinal. 70 // We key off of ordinal (instead of just looking up all fields in the 71 // StreamExecutorConfig) for a slight improvement in lookup time. 72 absl::Mutex mutex_; 73 std::map<int, Entry> cache_ TF_GUARDED_BY(mutex_); 74 75 SE_DISALLOW_COPY_AND_ASSIGN(ExecutorCache); 76 }; 77 78 } // namespace stream_executor 79 80 #endif // TENSORFLOW_STREAM_EXECUTOR_EXECUTOR_CACHE_H_ 81