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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 #include "net/disk_cache/blockfile/in_flight_io.h"
      6 
      7 #include "base/bind.h"
      8 #include "base/location.h"
      9 #include "base/logging.h"
     10 #include "base/single_thread_task_runner.h"
     11 #include "base/task_runner.h"
     12 #include "base/thread_task_runner_handle.h"
     13 #include "base/threading/thread_restrictions.h"
     14 
     15 namespace disk_cache {
     16 
     17 BackgroundIO::BackgroundIO(InFlightIO* controller)
     18     : result_(-1), io_completed_(true, false), controller_(controller) {
     19 }
     20 
     21 // Runs on the primary thread.
     22 void BackgroundIO::OnIOSignalled() {
     23   if (controller_)
     24     controller_->InvokeCallback(this, false);
     25 }
     26 
     27 void BackgroundIO::Cancel() {
     28   // controller_ may be in use from the background thread at this time.
     29   base::AutoLock lock(controller_lock_);
     30   DCHECK(controller_);
     31   controller_ = NULL;
     32 }
     33 
     34 BackgroundIO::~BackgroundIO() {
     35 }
     36 
     37 // ---------------------------------------------------------------------------
     38 
     39 InFlightIO::InFlightIO()
     40     : callback_task_runner_(base::ThreadTaskRunnerHandle::Get()),
     41       running_(false),
     42       single_thread_(false) {
     43 }
     44 
     45 InFlightIO::~InFlightIO() {
     46 }
     47 
     48 // Runs on the background thread.
     49 void BackgroundIO::NotifyController() {
     50   base::AutoLock lock(controller_lock_);
     51   if (controller_)
     52     controller_->OnIOComplete(this);
     53 }
     54 
     55 void InFlightIO::WaitForPendingIO() {
     56   while (!io_list_.empty()) {
     57     // Block the current thread until all pending IO completes.
     58     IOList::iterator it = io_list_.begin();
     59     InvokeCallback(it->get(), true);
     60   }
     61 }
     62 
     63 void InFlightIO::DropPendingIO() {
     64   while (!io_list_.empty()) {
     65     IOList::iterator it = io_list_.begin();
     66     BackgroundIO* operation = it->get();
     67     operation->Cancel();
     68     DCHECK(io_list_.find(operation) != io_list_.end());
     69     io_list_.erase(make_scoped_refptr(operation));
     70   }
     71 }
     72 
     73 // Runs on a background thread.
     74 void InFlightIO::OnIOComplete(BackgroundIO* operation) {
     75 #ifndef NDEBUG
     76   if (callback_task_runner_->RunsTasksOnCurrentThread()) {
     77     DCHECK(single_thread_ || !running_);
     78     single_thread_ = true;
     79   }
     80 #endif
     81 
     82   callback_task_runner_->PostTask(
     83       FROM_HERE, base::Bind(&BackgroundIO::OnIOSignalled, operation));
     84   operation->io_completed()->Signal();
     85 }
     86 
     87 // Runs on the primary thread.
     88 void InFlightIO::InvokeCallback(BackgroundIO* operation, bool cancel_task) {
     89   {
     90     // http://crbug.com/74623
     91     base::ThreadRestrictions::ScopedAllowWait allow_wait;
     92     operation->io_completed()->Wait();
     93   }
     94   running_ = true;
     95 
     96   if (cancel_task)
     97     operation->Cancel();
     98 
     99   // Make sure that we remove the operation from the list before invoking the
    100   // callback (so that a subsequent cancel does not invoke the callback again).
    101   DCHECK(io_list_.find(operation) != io_list_.end());
    102   DCHECK(!operation->HasOneRef());
    103   io_list_.erase(make_scoped_refptr(operation));
    104   OnOperationComplete(operation, cancel_task);
    105 }
    106 
    107 // Runs on the primary thread.
    108 void InFlightIO::OnOperationPosted(BackgroundIO* operation) {
    109   DCHECK(callback_task_runner_->RunsTasksOnCurrentThread());
    110   io_list_.insert(make_scoped_refptr(operation));
    111 }
    112 
    113 }  // namespace disk_cache
    114