Workaround for a crashing appcache bug seen on the crash servers

webkit/appcache/appcache_service.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "webkit/appcache/appcache_service.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
@@ skipping 20 matching lines @@
 }
 
 }  // namespace
 
 AppCacheInfoCollection::AppCacheInfoCollection() {}
 
 AppCacheInfoCollection::~AppCacheInfoCollection() {}
 
 // AsyncHelper -------
 
-class AppCacheService::NewAsyncHelper
-    : public AppCacheStorage::Delegate {
- public:
-  NewAsyncHelper(AppCacheService* service,
-                 const net::CompletionCallback& callback)
-      : service_(service), callback_(callback) {
-    service_->pending_new_helpers_.insert(this);
-  }
-
-  virtual ~NewAsyncHelper() {
-    if (service_)
-      service_->pending_new_helpers_.erase(this);
-  }
-
-  virtual void Start() = 0;
-  virtual void Cancel();
-
- protected:
-  void CallCallback(int rv) {
-    if (!callback_.is_null()) {
-      // Defer to guarantee async completion.
-      MessageLoop::current()->PostTask(
-          FROM_HERE, base::Bind(&DeferredCallback, callback_, rv));
-    }
-    callback_.Reset();
-  }
-
-  AppCacheService* service_;
-  net::CompletionCallback callback_;
-};
-
-void AppCacheService::NewAsyncHelper::Cancel() {
-  if (!callback_.is_null()) {
-    callback_.Run(net::ERR_ABORTED);
-    callback_.Reset();
-  }
-
-  service_->storage()->CancelDelegateCallbacks(this);
-  service_ = NULL;
-}
-
 class AppCacheService::AsyncHelper
     : public AppCacheStorage::Delegate {
  public:
-  AsyncHelper(
-      AppCacheService* service, const net::CompletionCallback& callback)
-      : service_(service),
-        callback_(callback) {
+  AsyncHelper(AppCacheService* service,
+              const net::CompletionCallback& callback)
+      : service_(service), callback_(callback) {
     service_->pending_helpers_.insert(this);
   }
 
   virtual ~AsyncHelper() {
     if (service_)
       service_->pending_helpers_.erase(this);
   }
 
   virtual void Start() = 0;
   virtual void Cancel();
@@ skipping 16 matching lines @@
   if (!callback_.is_null()) {
     callback_.Run(net::ERR_ABORTED);
     callback_.Reset();
   }
   service_->storage()->CancelDelegateCallbacks(this);
   service_ = NULL;
 }
 
 // CanHandleOfflineHelper -------
 
-class AppCacheService::CanHandleOfflineHelper : NewAsyncHelper {
+class AppCacheService::CanHandleOfflineHelper : AsyncHelper {
  public:
   CanHandleOfflineHelper(
       AppCacheService* service, const GURL& url,
       const GURL& first_party, const net::CompletionCallback& callback)
-      : NewAsyncHelper(service, callback),
+      : AsyncHelper(service, callback),
         url_(url),
         first_party_(first_party) {
   }
 
   virtual void Start() {
     AppCachePolicy* policy = service_->appcache_policy();
     if (policy && !policy->CanLoadAppCache(url_, first_party_)) {
       CallCallback(net::ERR_FAILED);
       delete this;
       return;
@@ skipping 19 matching lines @@
       const GURL& url, const AppCacheEntry& entry,
       const GURL& fallback_url, const AppCacheEntry& fallback_entry,
       int64 cache_id, int64 group_id, const GURL& manifest_url) {
   bool can = (entry.has_response_id() || fallback_entry.has_response_id());
   CallCallback(can ? net::OK : net::ERR_FAILED);
   delete this;
 }
 
 // DeleteHelper -------
 
-class AppCacheService::DeleteHelper : public NewAsyncHelper {
+class AppCacheService::DeleteHelper : public AsyncHelper {
  public:
   DeleteHelper(
       AppCacheService* service, const GURL& manifest_url,
       const net::CompletionCallback& callback)
-      : NewAsyncHelper(service, callback), manifest_url_(manifest_url) {
+      : AsyncHelper(service, callback), manifest_url_(manifest_url) {
   }
 
   virtual void Start() {
     service_->storage()->LoadOrCreateGroup(manifest_url_, this);
   }
 
  private:
   // AppCacheStorage::Delegate implementation.
   virtual void OnGroupLoaded(
       appcache::AppCacheGroup* group, const GURL& manifest_url);
@@ skipping 17 matching lines @@
 }
 
 void AppCacheService::DeleteHelper::OnGroupMadeObsolete(
       appcache::AppCacheGroup* group, bool success) {
   CallCallback(success ? net::OK : net::ERR_FAILED);
   delete this;
 }
 
 // DeleteOriginHelper -------
 
-class AppCacheService::DeleteOriginHelper : public NewAsyncHelper {
+class AppCacheService::DeleteOriginHelper : public AsyncHelper {
  public:
   DeleteOriginHelper(
       AppCacheService* service, const GURL& origin,
       const net::CompletionCallback& callback)
-      : NewAsyncHelper(service, callback), origin_(origin),
+      : AsyncHelper(service, callback), origin_(origin),
         num_caches_to_delete_(0), successes_(0), failures_(0) {
   }
 
   virtual void Start() {
     // We start by listing all caches, continues in OnAllInfo().
     service_->storage()->GetAllInfo(this);
   }
 
  private:
   // AppCacheStorage::Delegate implementation.
@@ skipping 66 matching lines @@
   if ((successes_ + failures_) < num_caches_to_delete_)
     return;
 
   CallCallback(!failures_ ? net::OK : net::ERR_FAILED);
   delete this;
 }
 
 
 // GetInfoHelper -------
 
-class AppCacheService::GetInfoHelper : NewAsyncHelper {
+class AppCacheService::GetInfoHelper : AsyncHelper {
  public:
   GetInfoHelper(
       AppCacheService* service, AppCacheInfoCollection* collection,
       const net::CompletionCallback& callback)
-      : NewAsyncHelper(service, callback), collection_(collection) {
+      : AsyncHelper(service, callback), collection_(collection) {
   }
 
   virtual void Start() {
     service_->storage()->GetAllInfo(this);
   }
 
  private:
   // AppCacheStorage::Delegate implementation.
   virtual void OnAllInfo(AppCacheInfoCollection* collection);
 
@@ skipping 153 matching lines @@
     quota_manager_proxy_->RegisterClient(quota_client_);
   }
 }
 
 AppCacheService::~AppCacheService() {
   DCHECK(backends_.empty());
   std::for_each(pending_helpers_.begin(),
                 pending_helpers_.end(),
                 std::mem_fun(&AsyncHelper::Cancel));
   STLDeleteElements(&pending_helpers_);
-  std::for_each(pending_new_helpers_.begin(),
-                pending_new_helpers_.end(),
-                std::mem_fun(&NewAsyncHelper::Cancel));
-  STLDeleteElements(&pending_new_helpers_);
   if (quota_client_)
     quota_client_->NotifyAppCacheDestroyed();
 
   // Destroy storage_ first; ~AppCacheStorageImpl accesses other data members
   // (special_storage_policy_).
   storage_.reset();
 }
 
 void AppCacheService::Initialize(const FilePath& cache_directory,
                                  base::MessageLoopProxy* db_thread,
@@ skipping 53 matching lines @@
   backends_.insert(
       BackendMap::value_type(backend_impl->process_id(), backend_impl));
 }
 
 void AppCacheService::UnregisterBackend(
     AppCacheBackendImpl* backend_impl) {
   backends_.erase(backend_impl->process_id());
 }
 
 }  // namespace appcache