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      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 #include "tensorflow/core/common_runtime/device_factory.h"
     17 
     18 #include <memory>
     19 #include <string>
     20 #include <unordered_map>
     21 #include <vector>
     22 
     23 #include "tensorflow/core/lib/core/errors.h"
     24 #include "tensorflow/core/lib/strings/strcat.h"
     25 #include "tensorflow/core/platform/logging.h"
     26 #include "tensorflow/core/platform/mutex.h"
     27 #include "tensorflow/core/platform/types.h"
     28 #include "tensorflow/core/public/session_options.h"
     29 
     30 namespace tensorflow {
     31 
     32 namespace {
     33 
     34 static mutex* get_device_factory_lock() {
     35   static mutex device_factory_lock(LINKER_INITIALIZED);
     36   return &device_factory_lock;
     37 }
     38 
     39 struct FactoryItem {
     40   std::unique_ptr<DeviceFactory> factory;
     41   int priority;
     42 };
     43 
     44 std::unordered_map<string, FactoryItem>& device_factories() {
     45   static std::unordered_map<string, FactoryItem>* factories =
     46       new std::unordered_map<string, FactoryItem>;
     47   return *factories;
     48 }
     49 
     50 }  // namespace
     51 
     52 // static
     53 int32 DeviceFactory::DevicePriority(const string& device_type) {
     54   mutex_lock l(*get_device_factory_lock());
     55   std::unordered_map<string, FactoryItem>& factories = device_factories();
     56   auto iter = factories.find(device_type);
     57   if (iter != factories.end()) {
     58     return iter->second.priority;
     59   }
     60 
     61   return -1;
     62 }
     63 
     64 // static
     65 void DeviceFactory::Register(const string& device_type, DeviceFactory* factory,
     66                              int priority) {
     67   mutex_lock l(*get_device_factory_lock());
     68   std::unique_ptr<DeviceFactory> factory_ptr(factory);
     69   std::unordered_map<string, FactoryItem>& factories = device_factories();
     70   auto iter = factories.find(device_type);
     71   if (iter == factories.end()) {
     72     factories[device_type] = {std::move(factory_ptr), priority};
     73   } else {
     74     if (iter->second.priority < priority) {
     75       iter->second = {std::move(factory_ptr), priority};
     76     } else if (iter->second.priority == priority) {
     77       LOG(FATAL) << "Duplicate registration of device factory for type "
     78                  << device_type << " with the same priority " << priority;
     79     }
     80   }
     81 }
     82 
     83 DeviceFactory* DeviceFactory::GetFactory(const string& device_type) {
     84   mutex_lock l(*get_device_factory_lock());  // could use reader lock
     85   auto it = device_factories().find(device_type);
     86   if (it == device_factories().end()) {
     87     return nullptr;
     88   }
     89   return it->second.factory.get();
     90 }
     91 
     92 Status DeviceFactory::AddDevices(const SessionOptions& options,
     93                                  const string& name_prefix,
     94                                  std::vector<Device*>* devices) {
     95   // CPU first. A CPU device is required.
     96   auto cpu_factory = GetFactory("CPU");
     97   if (!cpu_factory) {
     98     return errors::NotFound(
     99         "CPU Factory not registered.  Did you link in threadpool_device?");
    100   }
    101   size_t init_size = devices->size();
    102   TF_RETURN_IF_ERROR(cpu_factory->CreateDevices(options, name_prefix, devices));
    103   if (devices->size() == init_size) {
    104     return errors::NotFound("No CPU devices are available in this process");
    105   }
    106 
    107   // Then the rest (including GPU).
    108   mutex_lock l(*get_device_factory_lock());
    109   for (auto& p : device_factories()) {
    110     auto factory = p.second.factory.get();
    111     if (factory != cpu_factory) {
    112       TF_RETURN_IF_ERROR(factory->CreateDevices(options, name_prefix, devices));
    113     }
    114   }
    115 
    116   return Status::OK();
    117 }
    118 
    119 Device* DeviceFactory::NewDevice(const string& type,
    120                                  const SessionOptions& options,
    121                                  const string& name_prefix) {
    122   auto device_factory = GetFactory(type);
    123   if (!device_factory) {
    124     return nullptr;
    125   }
    126   SessionOptions opt = options;
    127   (*opt.config.mutable_device_count())[type] = 1;
    128   std::vector<Device*> devices;
    129   TF_CHECK_OK(device_factory->CreateDevices(opt, name_prefix, &devices));
    130   CHECK_EQ(devices.size(), size_t{1});
    131   return devices[0];
    132 }
    133 
    134 }  // namespace tensorflow
    135