net/disk_cache/blockfile/in_flight_io.cc

   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