Change the API of disk_cache::CreateCacheBackend to use scoped_ptr

net/disk_cache/cache_creator.cc

 // Copyright (c) 2012 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 "base/files/file_path.h"
 #include "base/metrics/field_trial.h"
 #include "base/strings/stringprintf.h"
 #include "net/base/cache_type.h"
 #include "net/base/net_errors.h"
 #include "net/disk_cache/backend_impl.h"
 #include "net/disk_cache/cache_util.h"
+#include "net/disk_cache/disk_cache.h"
 #include "net/disk_cache/mem_backend_impl.h"
 #include "net/disk_cache/simple/simple_backend_impl.h"
 
 #ifdef USE_TRACING_CACHE_BACKEND
 #include "net/disk_cache/tracing_cache_backend.h"
 #endif
 
 namespace {
 
 // Builds an instance of the backend depending on platform, type, experiments
 // etc. Takes care of the retry state. This object will self-destroy when
 // finished.
 class CacheCreator {
  public:
   CacheCreator(const base::FilePath& path, bool force, int max_bytes,
                net::CacheType type, net::BackendType backend_type, uint32 flags,
                base::MessageLoopProxy* thread, net::NetLog* net_log,
-               disk_cache::Backend** backend,
+               scoped_ptr<disk_cache::Backend>* backend,
                const net::CompletionCallback& callback);
 
   // Creates the backend.
   int Run();
 
  private:
   ~CacheCreator();
 
   void DoCallback(int result);
 
   void OnIOComplete(int result);
 
   const base::FilePath path_;
   bool force_;
   bool retry_;
   int max_bytes_;
   net::CacheType type_;
   net::BackendType backend_type_;
   uint32 flags_;
   scoped_refptr<base::MessageLoopProxy> thread_;
-  disk_cache::Backend** backend_;
+  scoped_ptr<disk_cache::Backend>* backend_;
   net::CompletionCallback callback_;
-  disk_cache::Backend* created_cache_;
+  scoped_ptr<disk_cache::Backend> created_cache_;
   net::NetLog* net_log_;
 
   DISALLOW_COPY_AND_ASSIGN(CacheCreator);
 };
 
 CacheCreator::CacheCreator(
     const base::FilePath& path, bool force, int max_bytes,
     net::CacheType type, net::BackendType backend_type, uint32 flags,
     base::MessageLoopProxy* thread, net::NetLog* net_log,
-    disk_cache::Backend** backend,
+    scoped_ptr<disk_cache::Backend>* backend,
     const net::CompletionCallback& callback)
     : path_(path),
       force_(force),
       retry_(false),
       max_bytes_(max_bytes),
       type_(type),
       backend_type_(backend_type),
       flags_(flags),
       thread_(thread),
       backend_(backend),
       callback_(callback),
-      created_cache_(NULL),
       net_log_(net_log) {
 }
 
 CacheCreator::~CacheCreator() {
 }
 
 int CacheCreator::Run() {
   // TODO(gavinp,pasko): While simple backend development proceeds, we're only
   // testing it against net::DISK_CACHE. Turn it on for more cache types as
   // appropriate.
   if (backend_type_ == net::CACHE_BACKEND_SIMPLE && type_ == net::DISK_CACHE) {
     disk_cache::SimpleBackendImpl* simple_cache =
         new disk_cache::SimpleBackendImpl(path_, max_bytes_, type_,
                                           thread_.get(), net_log_);
-    created_cache_ = simple_cache;
+    created_cache_.reset(simple_cache);
     return simple_cache->Init(
         base::Bind(&CacheCreator::OnIOComplete, base::Unretained(this)));
   }
   disk_cache::BackendImpl* new_cache =
       new disk_cache::BackendImpl(path_, thread_.get(), net_log_);
-  created_cache_ = new_cache;
+  created_cache_.reset(new_cache);
   new_cache->SetMaxSize(max_bytes_);
   new_cache->SetType(type_);
   new_cache->SetFlags(flags_);
   int rv = new_cache->Init(
       base::Bind(&CacheCreator::OnIOComplete, base::Unretained(this)));
   DCHECK_EQ(net::ERR_IO_PENDING, rv);
   return rv;
 }
 
 void CacheCreator::DoCallback(int result) {
   DCHECK_NE(net::ERR_IO_PENDING, result);
   if (result == net::OK) {
 #ifndef USE_TRACING_CACHE_BACKEND
-    *backend_ = created_cache_;
+    *backend_ = created_cache_.Pass();
 #else
-    *backend_ = new disk_cache::TracingCacheBackend(created_cache_);
+    *backend_.reset(
+        new disk_cache::TracingCacheBackend(created_cache_.Pass()));
 #endif
   } else {
     LOG(ERROR) << "Unable to create cache";
-    *backend_ = NULL;
-    delete created_cache_;
   }
   callback_.Run(result);
   delete this;
 }
 
 // If the initialization of the cache fails, and |force| is true, we will
 // discard the whole cache and create a new one.
 void CacheCreator::OnIOComplete(int result) {
   if (result == net::OK || !force_ || retry_)
     return DoCallback(result);
 
   // This is a failure and we are supposed to try again, so delete the object,
   // delete all the files, and try again.
   retry_ = true;
-  delete created_cache_;
-  created_cache_ = NULL;
+  created_cache_.reset();
   if (!disk_cache::DelayedCacheCleanup(path_))
     return DoCallback(result);
 
   // The worker thread will start deleting files soon, but the original folder
   // is not there anymore... let's create a new set of files.
   int rv = Run();
   DCHECK_EQ(net::ERR_IO_PENDING, rv);
 }
 
 }  // namespace
 
 namespace disk_cache {
 
 int CreateCacheBackend(net::CacheType type,
                        net::BackendType backend_type,
                        const base::FilePath& path,
                        int max_bytes,
                        bool force, base::MessageLoopProxy* thread,
-                       net::NetLog* net_log, Backend** backend,
+                       net::NetLog* net_log, scoped_ptr<Backend>* backend,
                        const net::CompletionCallback& callback) {
   DCHECK(!callback.is_null());
   if (type == net::MEMORY_CACHE) {
     *backend = disk_cache::MemBackendImpl::CreateBackend(max_bytes, net_log);
     return *backend ? net::OK : net::ERR_FAILED;
   }
   DCHECK(thread);
   CacheCreator* creator = new CacheCreator(path, force, max_bytes, type,
                                            backend_type, kNone,
                                            thread, net_log, backend, callback);
   return creator->Run();
 }
 
 }  // namespace disk_cache