15821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Copyright (c) 2012 The Chromium Authors. All rights reserved. 25821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Use of this source code is governed by a BSD-style license that can be 35821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// found in the LICENSE file. 45821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 55821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#ifndef NET_DNS_SERIAL_WORKER_H_ 65821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define NET_DNS_SERIAL_WORKER_H_ 75821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 85821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#include <string> 95821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#include "base/compiler_specific.h" 115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#include "base/memory/ref_counted.h" 125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#include "net/base/net_export.h" 135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Forward declaration 155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)namespace base { 165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)class MessageLoopProxy; 175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)namespace net { 205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// SerialWorker executes a job on WorkerPool serially -- **once at a time**. 225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// On |WorkNow|, a call to |DoWork| is scheduled on the WorkerPool. Once it 235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// completes, |OnWorkFinished| is called on the origin thread. 245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// If |WorkNow| is called (1 or more times) while |DoWork| is already under way, 255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// |DoWork| will be called once: after current |DoWork| completes, before a 265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// call to |OnWorkFinished|. 275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// This behavior is designed for updating a result after some trigger, for 295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// example reading a file once FilePathWatcher indicates it changed. 305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Derived classes should store results of work done in |DoWork| in dedicated 325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// fields and read them in |OnWorkFinished| which is executed on the origin 335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// thread. This avoids the need to template this class. 345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// This implementation avoids locking by using the |state_| member to ensure 365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// that |DoWork| and |OnWorkFinished| cannot execute in parallel. 375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// TODO(szym): update to WorkerPool::PostTaskAndReply once available. 395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)class NET_EXPORT_PRIVATE SerialWorker 405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) : NON_EXPORTED_BASE(public base::RefCountedThreadSafe<SerialWorker>) { 415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) public: 425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) SerialWorker(); 435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Unless already scheduled, post |DoWork| to WorkerPool. 455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Made virtual to allow mocking. 465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) virtual void WorkNow(); 475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Stop scheduling jobs. 495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) void Cancel(); 505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) bool IsCancelled() const { return state_ == CANCELLED; } 525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) protected: 545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) friend class base::RefCountedThreadSafe<SerialWorker>; 555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // protected to allow sub-classing, but prevent deleting 565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) virtual ~SerialWorker(); 575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Executed on WorkerPool, at most once at a time. 595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) virtual void DoWork() = 0; 605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Executed on origin thread after |DoRead| completes. 625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) virtual void OnWorkFinished() = 0; 635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 64868fa2fe829687343ffae624259930155e16dbd8Torne (Richard Coles) base::MessageLoopProxy* loop() { return message_loop_.get(); } 655821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 665821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) private: 675821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) enum State { 685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) CANCELLED = -1, 695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) IDLE = 0, 705821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) WORKING, // |DoWorkJob| posted on WorkerPool, until |OnWorkJobFinished| 715821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PENDING, // |WorkNow| while WORKING, must re-do work 725821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) WAITING, // WorkerPool is busy, |RetryWork| is posted 735821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) }; 745821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 755821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Called on the worker thread, executes |DoWork| and notifies the origin 765821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // thread. 775821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) void DoWorkJob(); 785821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 795821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Called on the the origin thread after |DoWork| completes. 805821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) void OnWorkJobFinished(); 815821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 825821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Posted to message loop in case WorkerPool is busy. (state == WAITING) 835821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) void RetryWork(); 845821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 855821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Message loop for the thread of origin. 865821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) scoped_refptr<base::MessageLoopProxy> message_loop_; 875821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 885821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) State state_; 895821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 905821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) DISALLOW_COPY_AND_ASSIGN(SerialWorker); 915821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 925821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 935821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} // namespace net 945821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 955821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#endif // NET_DNS_SERIAL_WORKER_H_ 965821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 97