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| 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style license that can be | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 #ifndef NET_DNS_SERIAL_WORKER_H_ | |
| 6 #define NET_DNS_SERIAL_WORKER_H_ | |
| 7 | |
| 8 #include <string> | |
| 9 | |
| 10 #include "base/compiler_specific.h" | |
| 11 #include "base/memory/ref_counted.h" | |
| 12 #include "net/base/net_export.h" | |
| 13 | |
| 14 // Forward declaration | |
| 15 namespace base { | |
| 16 class MessageLoopProxy; | |
| 17 } | |
| 18 | |
| 19 namespace net { | |
| 20 | |
| 21 // SerialWorker executes a job on WorkerPool serially -- **once at a time**. | |
| 22 // On |WorkNow|, a call to |DoWork| is scheduled on the WorkerPool. Once it | |
| 23 // completes, |OnWorkFinished| is called on the origin thread. | |
| 24 // If |WorkNow| is called (1 or more times) while |DoWork| is already under way, | |
| 25 // |DoWork| will be called once: after current |DoWork| completes, before a | |
| 26 // call to |OnWorkFinished|. | |
| 27 // | |
| 28 // This behavior is designed for updating a result after some trigger, for | |
| 29 // example reading a file once FilePathWatcher indicates it changed. | |
| 30 // | |
| 31 // Derived classes should store results of work done in |DoWork| in dedicated | |
| 32 // fields and read them in |OnWorkFinished| which is executed on the origin | |
| 33 // thread. This avoids the need to template this class. | |
| 34 // | |
| 35 // This implementation avoids locking by using the |state_| member to ensure | |
| 36 // that |DoWork| and |OnWorkFinished| cannot execute in parallel. | |
| 37 // | |
| 38 // TODO(szym): update to WorkerPool::PostTaskAndReply once available. | |
| 39 class NET_EXPORT_PRIVATE SerialWorker | |
| 40 : NON_EXPORTED_BASE(public base::RefCountedThreadSafe<SerialWorker>) { | |
| 41 public: | |
| 42 SerialWorker(); | |
| 43 | |
| 44 // Unless already scheduled, post |DoWork| to WorkerPool. | |
| 45 // Made virtual to allow mocking. | |
| 46 virtual void WorkNow(); | |
| 47 | |
| 48 // Stop scheduling jobs. | |
| 49 void Cancel(); | |
| 50 | |
| 51 bool IsCancelled() const { return state_ == CANCELLED; } | |
| 52 | |
| 53 protected: | |
| 54 friend class base::RefCountedThreadSafe<SerialWorker>; | |
| 55 // protected to allow sub-classing, but prevent deleting | |
| 56 virtual ~SerialWorker(); | |
| 57 | |
| 58 // Executed on WorkerPool, at most once at a time. | |
| 59 virtual void DoWork() = 0; | |
| 60 | |
| 61 // Executed on origin thread after |DoRead| completes. | |
| 62 virtual void OnWorkFinished() = 0; | |
| 63 | |
| 64 base::MessageLoopProxy* loop() { return message_loop_.get(); } | |
| 65 | |
| 66 private: | |
| 67 enum State { | |
| 68 CANCELLED = -1, | |
| 69 IDLE = 0, | |
| 70 WORKING, // |DoWorkJob| posted on WorkerPool, until |OnWorkJobFinished| | |
| 71 PENDING, // |WorkNow| while WORKING, must re-do work | |
| 72 WAITING, // WorkerPool is busy, |RetryWork| is posted | |
| 73 }; | |
| 74 | |
| 75 // Called on the worker thread, executes |DoWork| and notifies the origin | |
| 76 // thread. | |
| 77 void DoWorkJob(); | |
| 78 | |
| 79 // Called on the the origin thread after |DoWork| completes. | |
| 80 void OnWorkJobFinished(); | |
| 81 | |
| 82 // Posted to message loop in case WorkerPool is busy. (state == WAITING) | |
| 83 void RetryWork(); | |
| 84 | |
| 85 // Message loop for the thread of origin. | |
| 86 scoped_refptr<base::MessageLoopProxy> message_loop_; | |
| 87 | |
| 88 State state_; | |
| 89 | |
| 90 DISALLOW_COPY_AND_ASSIGN(SerialWorker); | |
| 91 }; | |
| 92 | |
| 93 } // namespace net | |
| 94 | |
| 95 #endif // NET_DNS_SERIAL_WORKER_H_ | |
| 96 | |
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Chromium Code Reviews
Issue 992733002:
Remove //net (except for Android test stuff) and sdch (Closed)
Base URL: git@github.com:domokit/mojo.git@master