1/* Copyright 2018 The TensorFlow Authors. All Rights Reserved.
2
3Licensed under the Apache License, Version 2.0 (the "License");
4you may not use this file except in compliance with the License.
5You may obtain a copy of the License at
6
7 http://www.apache.org/licenses/LICENSE-2.0
8
9Unless required by applicable law or agreed to in writing, software
10distributed under the License is distributed on an "AS IS" BASIS,
11WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12See the License for the specific language governing permissions and
13limitations under the License.
14==============================================================================*/
15
16#include "tensorflow/tsl/platform/logger.h"
17
18#include "absl/base/call_once.h"
19#include "absl/synchronization/notification.h"
20#include "tensorflow/tsl/platform/env.h"
21#include "tensorflow/tsl/platform/logging.h"
22
23namespace tsl {
24namespace {
25
26class DefaultLogger : public Logger {
27 private:
28 void DoLogProto(google::protobuf::Any* proto) override {}
29 void DoFlush() override {}
30};
31
32} // namespace
33
34Logger::FactoryFunc Logger::singleton_factory_ = []() -> Logger* {
35 return new DefaultLogger();
36};
37
38struct LoggerSingletonContainer {
39 // Used to kick off the construction of a new thread that will asynchronously
40 // construct a Logger.
41 absl::once_flag start_initialization_thread_flag;
42
43 // The constructed logger, if there is one.
44 Logger* logger;
45
46 // The initializing thread notifies `logger_initialized` after storing the
47 // constructed logger to `logger`.
48 absl::Notification logger_initialized;
49
50 // The thread used to construct the Logger instance asynchronously.
51 std::unique_ptr<Thread> initialization_thread;
52
53 // Used to kick off the joining and destruction of `initialization_thread`.
54 absl::once_flag delete_initialization_thread_flag;
55};
56
57LoggerSingletonContainer* GetLoggerSingletonContainer() {
58 static LoggerSingletonContainer* container = new LoggerSingletonContainer;
59 return container;
60}
61
62struct AsyncSingletonImpl {
63 static void InitializationThreadFn() {
64 LoggerSingletonContainer* container = GetLoggerSingletonContainer();
65 container->logger = Logger::singleton_factory_();
66 container->logger_initialized.Notify();
67 }
68
69 static void StartInitializationThread(LoggerSingletonContainer* container) {
70 Thread* thread =
71 Env::Default()->StartThread(ThreadOptions{}, "logger-init-thread",
72 AsyncSingletonImpl::InitializationThreadFn);
73 container->initialization_thread.reset(thread);
74 }
75};
76
77/*static*/ Logger* Logger::GetSingleton() {
78 // Call the async version to kick off the initialization thread if necessary.
79 (void)Logger::GetSingletonAsync();
80
81 // And wait for the thread to finish.
82 LoggerSingletonContainer* container = GetLoggerSingletonContainer();
83 absl::call_once(container->delete_initialization_thread_flag,
84 [container]() { container->initialization_thread.reset(); });
85
86 return container->logger;
87}
88
89/*static*/ Logger* Logger::GetSingletonAsync() {
90 LoggerSingletonContainer* container = GetLoggerSingletonContainer();
91 absl::call_once(container->start_initialization_thread_flag,
92 AsyncSingletonImpl::StartInitializationThread, container);
93
94 if (container->logger_initialized.HasBeenNotified()) {
95 // Wait for the initializing thread to finish to reclaim resources.
96 absl::call_once(
97 container->delete_initialization_thread_flag,
98 [container]() { container->initialization_thread.reset(); });
99 return container->logger;
100 } else {
101 return nullptr;
102 }
103}
104} // namespace tsl
105