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      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 #include "tensorflow/core/distributed_runtime/device_resolver_distributed.h"
     16 
     17 #include "tensorflow/core/common_runtime/device_mgr.h"
     18 #include "tensorflow/core/distributed_runtime/worker_cache.h"
     19 
     20 namespace tensorflow {
     21 DeviceResolverDistributed::DeviceResolverDistributed(
     22     const DeviceMgr* dev_mgr, WorkerCacheInterface* worker_cache,
     23     const string& task_name)
     24     : dev_mgr_(dev_mgr), worker_cache_(worker_cache), task_name_(task_name) {}
     25 
     26 void DeviceResolverDistributed::GetLocalityAsync(const string& device,
     27                                                  const string& task,
     28                                                  DeviceLocality* locality,
     29                                                  const StatusCallback& done) {
     30   if (task.empty() || task == task_name_) {
     31     // Device is local to this task.
     32     Device* dev;
     33     Status s = dev_mgr_->LookupDevice(device, &dev);
     34     if (s.ok()) {
     35       *locality = dev->attributes().locality();
     36     }
     37     done(s);
     38     return;
     39   } else {
     40     // Lookup of a remote device: first try the local cache.
     41     bool found = false;
     42     {
     43       mutex_lock l(mu_);
     44       auto it = attr_table_.find(device);
     45       if (it != attr_table_.end()) {
     46         *locality = it->second.locality();
     47         found = true;
     48       }
     49     }
     50     if (found) {
     51       done(Status::OK());
     52       return;
     53     }
     54   }
     55   // Device is remote and no cache entry was found.  Refresh the cache
     56   // then retry the lookup.
     57   RefreshRemoteAttributes(
     58       device, task, [this, device, task, locality, done](const Status& s) {
     59         if (!s.ok()) {
     60           done(s);
     61         } else {
     62           GetLocalityAsync(device, task, locality, done);
     63         }
     64       });
     65 }
     66 
     67 void DeviceResolverDistributed::GetDeviceLocalitiesAsync(
     68     const CollInstanceParams& inst_params,
     69     std::vector<DeviceLocality>* localities, const StatusCallback& done) {
     70   localities->clear();
     71   GetDeviceLocalitiesRecursive(inst_params, localities, done);
     72 }
     73 
     74 void DeviceResolverDistributed::GetDeviceLocalitiesRecursive(
     75     const CollInstanceParams& inst_params,
     76     std::vector<DeviceLocality>* localities, const StatusCallback& done) {
     77   size_t i = localities->size();
     78   if (i < inst_params.device_names.size()) {
     79     localities->push_back(DeviceLocality());
     80     GetLocalityAsync(inst_params.device_names[i], inst_params.task_names[i],
     81                      &localities->back(),
     82                      [this, &inst_params, localities, done](const Status& s) {
     83                        if (!s.ok()) {
     84                          done(s);
     85                          return;
     86                        } else {
     87                          GetDeviceLocalitiesRecursive(inst_params, localities,
     88                                                       done);
     89                        }
     90                      });
     91   } else {
     92     done(Status::OK());
     93   }
     94 }
     95 
     96 void DeviceResolverDistributed::RefreshRemoteAttributes(
     97     const string& device, const string& task, const StatusCallback& done) {
     98   GetStatusRequest* req = new GetStatusRequest;
     99   GetStatusResponse* resp = new GetStatusResponse;
    100   WorkerInterface* worker = worker_cache_->CreateWorker(task);
    101   CHECK(worker) << "Failed to get worker for " << task;
    102   worker->GetStatusAsync(
    103       req, resp, [this, device, task, req, resp, worker, done](Status s) {
    104         if (s.ok()) {
    105           mutex_lock l(mu_);
    106           for (const DeviceAttributes& da : resp->device_attributes()) {
    107             attr_table_[da.name()] = da;
    108           }
    109         }
    110         done(s);
    111         delete req;
    112         delete resp;
    113         worker_cache_->ReleaseWorker(task, worker);
    114       });
    115 }
    116 
    117 void DeviceResolverDistributed::ClearTask(const string& task) {
    118   mutex_lock l(mu_);
    119   // First find all the keys belonging to the task.
    120   std::unordered_set<string> task_keys;
    121   for (const auto& it : attr_table_) {
    122     const string& device_name = it.first;
    123     if (DeviceNameUtils::IsSameAddressSpace(task, device_name)) {
    124       task_keys.insert(device_name);
    125     }
    126   }
    127   // Then delete them.
    128   for (const string& key : task_keys) {
    129     attr_table_.erase(key);
    130   }
    131 }
    132 
    133 }  // namespace tensorflow
    134