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