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_TSL_PLATFORM_DEFAULT_NOTIFICATION_H_ |
17 | #define TENSORFLOW_TSL_PLATFORM_DEFAULT_NOTIFICATION_H_ |
18 | |
19 | #include <assert.h> |
20 | |
21 | #include <atomic> // NOLINT |
22 | #include <chrono> // NOLINT |
23 | #include <condition_variable> // NOLINT |
24 | |
25 | #include "tensorflow/tsl/platform/mutex.h" |
26 | #include "tensorflow/tsl/platform/types.h" |
27 | |
28 | namespace tsl { |
29 | |
30 | class Notification { |
31 | public: |
32 | Notification() : notified_(0) {} |
33 | ~Notification() { |
34 | // In case the notification is being used to synchronize its own deletion, |
35 | // force any prior notifier to leave its critical section before the object |
36 | // is destroyed. |
37 | mutex_lock l(mu_); |
38 | } |
39 | |
40 | void Notify() { |
41 | mutex_lock l(mu_); |
42 | assert(!HasBeenNotified()); |
43 | notified_.store(true, std::memory_order_release); |
44 | cv_.notify_all(); |
45 | } |
46 | |
47 | bool HasBeenNotified() const { |
48 | return notified_.load(std::memory_order_acquire); |
49 | } |
50 | |
51 | void WaitForNotification() { |
52 | if (!HasBeenNotified()) { |
53 | mutex_lock l(mu_); |
54 | while (!HasBeenNotified()) { |
55 | cv_.wait(l); |
56 | } |
57 | } |
58 | } |
59 | |
60 | private: |
61 | friend bool WaitForNotificationWithTimeout(Notification* n, |
62 | int64_t timeout_in_us); |
63 | bool WaitForNotificationWithTimeout(int64_t timeout_in_us) { |
64 | bool notified = HasBeenNotified(); |
65 | if (!notified) { |
66 | mutex_lock l(mu_); |
67 | do { |
68 | notified = HasBeenNotified(); |
69 | } while (!notified && |
70 | cv_.wait_for(l, std::chrono::microseconds(timeout_in_us)) != |
71 | std::cv_status::timeout); |
72 | } |
73 | return notified; |
74 | } |
75 | |
76 | mutex mu_; // protects mutations of notified_ |
77 | condition_variable cv_; // signaled when notified_ becomes non-zero |
78 | std::atomic<bool> notified_; // mutations under mu_ |
79 | }; |
80 | |
81 | inline bool WaitForNotificationWithTimeout(Notification* n, |
82 | int64_t timeout_in_us) { |
83 | return n->WaitForNotificationWithTimeout(timeout_in_us); |
84 | } |
85 | |
86 | } // namespace tsl |
87 | |
88 | #endif // TENSORFLOW_TSL_PLATFORM_DEFAULT_NOTIFICATION_H_ |
89 |