1 /* Copyright 2018 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_SERVICE_MAYBE_OWNING_DEVICE_MEMORY_H_ 17 #define TENSORFLOW_COMPILER_XLA_SERVICE_MAYBE_OWNING_DEVICE_MEMORY_H_ 18 19 #include "absl/types/optional.h" 20 #include "absl/types/variant.h" 21 #include "tensorflow/compiler/xla/service/device_memory_allocator.h" 22 #include "tensorflow/compiler/xla/service/owning_device_memory.h" 23 24 namespace xla { 25 26 // MaybeOwningDeviceMemory represents either an owned or unowned device memory. 27 // Like std::variant<OwningDeviceMemory, DeviceMemory>. When the object goes 28 // output of scope, it will free the underlying memory if it owns it. 29 class MaybeOwningDeviceMemory { 30 public: 31 MaybeOwningDeviceMemory() = default; MaybeOwningDeviceMemory(OwningDeviceMemory owned)32 explicit MaybeOwningDeviceMemory(OwningDeviceMemory owned) 33 : mem_(std::move(owned)) {} MaybeOwningDeviceMemory(se::DeviceMemoryBase unowned)34 explicit MaybeOwningDeviceMemory(se::DeviceMemoryBase unowned) 35 : mem_(unowned) {} 36 MaybeOwningDeviceMemory(MaybeOwningDeviceMemory&&) = default; 37 ~MaybeOwningDeviceMemory() = default; 38 39 MaybeOwningDeviceMemory& operator=(se::DeviceMemoryBase unowned) { 40 mem_ = unowned; 41 return *this; 42 } 43 44 MaybeOwningDeviceMemory& operator=(OwningDeviceMemory owned) { 45 mem_ = std::move(owned); 46 return *this; 47 } 48 49 MaybeOwningDeviceMemory& operator=(MaybeOwningDeviceMemory&&) = default; 50 51 // Fetches the underlying DeviceMemoryBase from a MaybeOwningDeviceMemory. The 52 // caller of this function is *not* responsible for freeing the memory. 53 se::DeviceMemoryBase AsDeviceMemoryBase(); 54 55 // Release the OwningDeviceMemory without freeing it, and moves the ownership 56 // of the memory buffer from the object to the caller. 57 // 58 // A nullopt is returned if the HasOwnership() == false; 59 absl::optional<OwningDeviceMemory> Release(); 60 61 // Returns true if the device_memory has ownership over underlying memory. 62 bool HasOwnership() const; 63 64 private: 65 absl::variant<OwningDeviceMemory, se::DeviceMemoryBase> mem_; 66 }; 67 68 } // namespace xla 69 70 #endif // TENSORFLOW_COMPILER_XLA_SERVICE_MAYBE_OWNING_DEVICE_MEMORY_H_ 71