src/chrome/browser/common/cancelable_request.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 "chrome/browser/common/cancelable_request.h"
   6
   7 CancelableRequestProvider::CancelableRequestProvider()
   8     : next_handle_(1) {
   9 }
  10
  11 CancelableRequestProvider::Handle CancelableRequestProvider::AddRequest(
  12     CancelableRequestBase* request,
  13     CancelableRequestConsumerBase* consumer) {
  14   Handle handle;
  15   {
  16     base::AutoLock lock(pending_request_lock_);
  17
  18     handle = next_handle_;
  19     pending_requests_[next_handle_] = request;
  20     ++next_handle_;
  21     DCHECK(next_handle_)
  22         << "next_handle_ may have wrapped around to invalid state.";
  23   }
  24
  25   consumer->OnRequestAdded(this, handle);
  26
  27   request->Init(this, handle, consumer);
  28   return handle;
  29 }
  30
  31 void CancelableRequestProvider::CancelRequest(Handle handle) {
  32   base::AutoLock lock(pending_request_lock_);
  33   CancelRequestLocked(pending_requests_.find(handle));
  34 }
  35
  36 CancelableRequestProvider::~CancelableRequestProvider() {
  37   // There may be requests whose result callback has not been run yet. We need
  38   // to cancel them otherwise they may try and call us back after we've been
  39   // deleted, or do other bad things. This can occur on shutdown (or browser
  40   // context destruction) when a request is scheduled, completed (but not
  41   // dispatched), then the BrowserContext is deleted.
  42   base::AutoLock lock(pending_request_lock_);
  43   while (!pending_requests_.empty())
  44     CancelRequestLocked(pending_requests_.begin());
  45 }
  46
  47 void CancelableRequestProvider::CancelRequestLocked(
  48     const CancelableRequestMap::iterator& item) {
  49   pending_request_lock_.AssertAcquired();
  50   if (item == pending_requests_.end()) {
  51     NOTREACHED() << "Trying to cancel an unknown request";
  52     return;
  53   }
  54
  55   item->second->consumer()->OnRequestRemoved(this, item->first);
  56   item->second->set_canceled();
  57   pending_requests_.erase(item);
  58 }
  59
  60 void CancelableRequestProvider::RequestCompleted(Handle handle) {
  61   CancelableRequestConsumerBase* consumer = NULL;
  62   {
  63     base::AutoLock lock(pending_request_lock_);
  64
  65     CancelableRequestMap::iterator i = pending_requests_.find(handle);
  66     if (i == pending_requests_.end()) {
  67       NOTREACHED() << "Trying to cancel an unknown request";
  68       return;
  69     }
  70     consumer = i->second->consumer();
  71
  72     // This message should only get sent if the class is not cancelled, or
  73     // else the consumer might be gone).
  74     DCHECK(!i->second->canceled());
  75
  76     pending_requests_.erase(i);
  77   }
  78
  79   // Notify the consumer that the request is gone
  80   consumer->OnRequestRemoved(this, handle);
  81 }
  82
  83 // MSVC doesn't like complex extern templates and DLLs.
  84 #if !defined(COMPILER_MSVC)
  85 // Emit our most common CancelableRequestConsumer.
  86 template class CancelableRequestConsumerTSimple<int>;
  87
  88 // And the most common subclass of it.
  89 template class CancelableRequestConsumerT<int, 0>;
  90 #endif
  91
  92 CancelableRequestBase::CancelableRequestBase()
  93     : provider_(NULL),
  94       consumer_(NULL),
  95       handle_(0) {
  96   callback_thread_ = base::MessageLoop::current();
  97 }
  98
  99 CancelableRequestBase::~CancelableRequestBase() {
 100 }
 101
 102 void CancelableRequestBase::Init(CancelableRequestProvider* provider,
 103                                  CancelableRequestProvider::Handle handle,
 104                                  CancelableRequestConsumerBase* consumer) {
 105   DCHECK(handle_ == 0 && provider_ == NULL && consumer_ == NULL);
 106   provider_ = provider;
 107   consumer_ = consumer;
 108   handle_ = handle;
 109 }
 110
 111 void CancelableRequestBase::DoForward(const base::Closure& forwarded_call,
 112                                       bool force_async) {
 113   if (force_async || callback_thread_ != base::MessageLoop::current()) {
 114     callback_thread_->PostTask(
 115         FROM_HERE,
 116         base::Bind(&CancelableRequestBase::ExecuteCallback, this,
 117                    forwarded_call));
 118   } else {
 119     // We can do synchronous callbacks when we're on the same thread.
 120     ExecuteCallback(forwarded_call);
 121   }
 122 }
 123
 124 void CancelableRequestBase::ExecuteCallback(
 125     const base::Closure& forwarded_call) {
 126   DCHECK_EQ(callback_thread_, base::MessageLoop::current());
 127
 128   if (!canceled_.IsSet()) {
 129     WillExecute();
 130
 131     // Execute the callback.
 132     forwarded_call.Run();
 133   }
 134
 135   // Notify the provider that the request is complete. The provider will
 136   // notify the consumer for us. Note that it is possible for the callback to
 137   // cancel this request; we must check canceled again.
 138   if (!canceled_.IsSet())
 139     NotifyCompleted();
 140 }