Revert 51456 - Disk cache: Switch the disk cache to use the cache_thread....

net/disk_cache/backend_impl.cc

Index: net/disk_cache/backend_impl.cc
===================================================================
--- net/disk_cache/backend_impl.cc	(revision 51468)
+++ net/disk_cache/backend_impl.cc	(working copy)
@@ -162,105 +162,6 @@
   trial1->AppendGroup(group1, FieldTrial::kAllRemainingProbability);
 }
 
-// ------------------------------------------------------------------------
-
-// This class takes care of building an instance of the backend.
-class CacheCreator {
- public:
-  CacheCreator(const FilePath& path, bool force, int max_bytes,
-               net::CacheType type, uint32 flags,
-               base::MessageLoopProxy* thread, disk_cache::Backend** backend,
-               net::CompletionCallback* callback)
-      : path_(path), force_(force), retry_(false), max_bytes_(max_bytes),
-        type_(type), flags_(flags), thread_(thread), backend_(backend),
-        callback_(callback), cache_(NULL),
-        ALLOW_THIS_IN_INITIALIZER_LIST(
-            my_callback_(this, &CacheCreator::OnIOComplete)) {
-  }
-  ~CacheCreator() {}
-
-  // Creates the backend.
-  int Run();
-
-  // Callback implementation.
-  void OnIOComplete(int result);
-
- private:
-  void DoCallback(int result);
-
-  const FilePath& path_;
-  bool force_;
-  bool retry_;
-  int max_bytes_;
-  net::CacheType type_;
-  uint32 flags_;
-  scoped_refptr<base::MessageLoopProxy> thread_;
-  disk_cache::Backend** backend_;
-  net::CompletionCallback* callback_;
-  disk_cache::BackendImpl* cache_;
-  net::CompletionCallbackImpl<CacheCreator> my_callback_;
-
-  DISALLOW_COPY_AND_ASSIGN(CacheCreator);
-};
-
-int CacheCreator::Run() {
-  cache_ = new disk_cache::BackendImpl(path_, thread_);
-  cache_->SetMaxSize(max_bytes_);
-  cache_->SetType(type_);
-  cache_->SetFlags(flags_);
-  int rv = cache_->Init(&my_callback_);
-  DCHECK_EQ(net::ERR_IO_PENDING, rv);
-  return rv;
-}
-
-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 cache_;
-  if (!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);
-}
-
-void CacheCreator::DoCallback(int result) {
-  DCHECK_NE(net::ERR_IO_PENDING, result);
-  if (result == net::OK) {
-    *backend_ = cache_;
-  } else {
-    LOG(ERROR) << "Unable to create cache";
-    *backend_ = NULL;
-    delete cache_;
-  }
-  callback_->Run(result);
-  delete this;
-}
-
-// ------------------------------------------------------------------------
-
-// A task to perform final cleanup on the background thread.
-class FinalCleanup : public Task {
- public:
-  explicit FinalCleanup(disk_cache::BackendImpl* backend) : backend_(backend) {}
-  ~FinalCleanup() {}
-
-  virtual void Run();
- private:
-  disk_cache::BackendImpl* backend_;
-  DISALLOW_EVIL_CONSTRUCTORS(FinalCleanup);
-};
-
-void FinalCleanup::Run() {
-  backend_->CleanupCache();
-}
-
 }  // namespace
 
 // ------------------------------------------------------------------------
@@ -327,16 +228,36 @@
                                uint32 flags, base::MessageLoopProxy* thread,
                                Backend** backend,
                                CompletionCallback* callback) {
-  CacheCreator* creator = new CacheCreator(full_path, force, max_bytes, type,
-                                           flags, thread, backend, callback);
-  // This object will self-destroy when finished.
-  return creator->Run();
-}
+  BackendImpl* cache = new BackendImpl(full_path, thread);
+  cache->SetMaxSize(max_bytes);
+  cache->SetType(type);
+  cache->SetFlags(flags);
+  if (cache->Init()) {
+    *backend = cache;
+    return net::OK;
+  }
 
-int BackendImpl::SyncInit() {
-  if (Init())
+  *backend = NULL;
+  delete cache;
+  if (!force)
+    return net::ERR_FAILED;
+
+  if (!DelayedCacheCleanup(full_path))
+    return net::ERR_FAILED;
+
+  // The worker thread will start deleting files soon, but the original folder
+  // is not there anymore... let's create a new set of files.
+  cache = new BackendImpl(full_path, thread);
+  cache->SetMaxSize(max_bytes);
+  cache->SetType(type);
+  cache->SetFlags(flags);
+  if (cache->Init()) {
+    *backend = cache;
     return net::OK;
+  }
 
+  delete cache;
+  LOG(ERROR) << "Unable to create cache";
   return net::ERR_FAILED;
 }
 
@@ -383,7 +304,7 @@
 
   // We don't care if the value overflows. The only thing we care about is that
   // the id cannot be zero, because that value is used as "not dirty".
-  // Increasing the value once per second gives us many years before we start
+  // Increasing the value once per second gives us many years before a we start
   // having collisions.
   data_->header.this_id++;
   if (!data_->header.this_id)
@@ -414,37 +335,18 @@
   return !disabled_;
 }
 
-int BackendImpl::Init(CompletionCallback* callback) {
-  background_queue_.Init(callback);
-  return net::ERR_IO_PENDING;
-}
-
 BackendImpl::~BackendImpl() {
+  Trace("Backend destructor");
   if (!init_)
     return;
 
   if (data_)
     data_->header.crash = 0;
 
-  background_queue_.WaitForPendingIO();
-
-  if (background_queue_.BackgroundIsCurrentThread()) {
-    // Unit tests may use the same thread for everything.
-    CleanupCache();
-  } else {
-    background_queue_.background_thread()->PostTask(FROM_HERE,
-                                                    new FinalCleanup(this));
-    done_.Wait();
-  }
-}
-
-void BackendImpl::CleanupCache() {
-  Trace("Backend Cleanup");
   timer_.Stop();
+
   File::WaitForPendingIO(&num_pending_io_);
   DCHECK(!num_refs_);
-  factory_.RevokeAll();
-  done_.Signal();
 }
 
 // ------------------------------------------------------------------------
@@ -491,17 +393,18 @@
   return cache_entry;
 }
 
-int BackendImpl::SyncOpenEntry(const std::string& key, Entry** entry) {
+bool BackendImpl::OpenEntry(const std::string& key, Entry** entry) {
   DCHECK(entry);
   *entry = OpenEntryImpl(key);
-  return (*entry) ? net::OK : net::ERR_FAILED;
+  return (*entry) ? true : false;
 }
 
 int BackendImpl::OpenEntry(const std::string& key, Entry** entry,
                            CompletionCallback* callback) {
-  DCHECK(callback);
-  background_queue_.OpenEntry(key, entry, callback);
-  return net::ERR_IO_PENDING;
+  if (OpenEntry(key, entry))
+    return net::OK;
+
+  return net::ERR_FAILED;
 }
 
 EntryImpl* BackendImpl::CreateEntryImpl(const std::string& key) {
@@ -581,21 +484,15 @@
   return cache_entry.release();
 }
 
-int BackendImpl::SyncCreateEntry(const std::string& key, Entry** entry) {
+bool BackendImpl::CreateEntry(const std::string& key, Entry** entry) {
   DCHECK(entry);
   *entry = CreateEntryImpl(key);
-  return (*entry) ? net::OK : net::ERR_FAILED;
+  return (*entry) ? true : false;
 }
 
 int BackendImpl::CreateEntry(const std::string& key, Entry** entry,
                              CompletionCallback* callback) {
-  DCHECK(callback);
-  background_queue_.CreateEntry(key, entry, callback);
-  return net::ERR_IO_PENDING;
-}
-
-int BackendImpl::SyncDoomEntry(const std::string& key) {
-  if (DoomEntry(key))
+  if (CreateEntry(key, entry))
     return net::OK;
 
   return net::ERR_FAILED;
@@ -605,24 +502,21 @@
   if (disabled_)
     return false;
 
-  EntryImpl* entry = OpenEntryImpl(key);
-  if (!entry)
+  Entry* entry;
+  if (!OpenEntry(key, &entry))
     return false;
 
-  entry->DoomImpl();
-  entry->Release();
+  // Note that you'd think you could just pass &entry_impl to OpenEntry,
+  // but that triggers strict aliasing problems with gcc.
+  EntryImpl* entry_impl = reinterpret_cast<EntryImpl*>(entry);
+  entry_impl->Doom();
+  entry_impl->Release();
   return true;
 }
 
 int BackendImpl::DoomEntry(const std::string& key,
                            CompletionCallback* callback) {
-  DCHECK(callback);
-  background_queue_.DoomEntry(key, callback);
-  return net::ERR_IO_PENDING;
-}
-
-int BackendImpl::SyncDoomAllEntries() {
-  if (DoomAllEntries())
+  if (DoomEntry(key))
     return net::OK;
 
   return net::ERR_FAILED;
@@ -644,14 +538,7 @@
 }
 
 int BackendImpl::DoomAllEntries(CompletionCallback* callback) {
-  DCHECK(callback);
-  background_queue_.DoomAllEntries(callback);
-  return net::ERR_IO_PENDING;
-}
-
-int BackendImpl::SyncDoomEntriesBetween(const base::Time initial_time,
-                                        const base::Time end_time) {
-  if (DoomEntriesBetween(initial_time, end_time))
+  if (DoomAllEntries())
     return net::OK;
 
   return net::ERR_FAILED;
@@ -667,27 +554,27 @@
   if (disabled_)
     return false;
 
-  EntryImpl* node;
+  Entry* node, *next;
   void* iter = NULL;
-  EntryImpl* next = OpenNextEntryImpl(&iter);
-  if (!next)
+  if (!OpenNextEntry(&iter, &next))
     return true;
 
   while (next) {
     node = next;
-    next = OpenNextEntryImpl(&iter);
+    if (!OpenNextEntry(&iter, &next))
+      next = NULL;
 
     if (node->GetLastUsed() >= initial_time &&
         node->GetLastUsed() < end_time) {
-      node->DoomImpl();
+      node->Doom();
     } else if (node->GetLastUsed() < initial_time) {
       if (next)
-        next->Release();
+        next->Close();
       next = NULL;
-      SyncEndEnumeration(iter);
+      EndEnumeration(&iter);
     }
 
-    node->Release();
+    node->Close();
   }
 
   return true;
@@ -696,72 +583,59 @@
 int BackendImpl::DoomEntriesBetween(const base::Time initial_time,
                                     const base::Time end_time,
                                     CompletionCallback* callback) {
-  DCHECK(callback);
-  background_queue_.DoomEntriesBetween(initial_time, end_time, callback);
-  return net::ERR_IO_PENDING;
-}
-
-int BackendImpl::SyncDoomEntriesSince(const base::Time initial_time) {
-  if (DoomEntriesSince(initial_time))
+  if (DoomEntriesBetween(initial_time, end_time))
     return net::OK;
 
   return net::ERR_FAILED;
 }
 
-// We use OpenNextEntryImpl to retrieve elements from the cache, until we get
+// We use OpenNextEntry to retrieve elements from the cache, until we get
 // entries that are too old.
 bool BackendImpl::DoomEntriesSince(const Time initial_time) {
   if (disabled_)
     return false;
 
   for (;;) {
+    Entry* entry;
     void* iter = NULL;
-    EntryImpl* entry = OpenNextEntryImpl(&iter);
-    if (!entry)
+    if (!OpenNextEntry(&iter, &entry))
       return true;
 
     if (initial_time > entry->GetLastUsed()) {
-      entry->Release();
-      SyncEndEnumeration(iter);
+      entry->Close();
+      EndEnumeration(&iter);
       return true;
     }
 
-    entry->DoomImpl();
-    entry->Release();
-    SyncEndEnumeration(iter);  // Dooming the entry invalidates the iterator.
+    entry->Doom();
+    entry->Close();
+    EndEnumeration(&iter);  // Dooming the entry invalidates the iterator.
   }
 }
 
 int BackendImpl::DoomEntriesSince(const base::Time initial_time,
                                   CompletionCallback* callback) {
-  DCHECK(callback);
-  background_queue_.DoomEntriesSince(initial_time, callback);
-  return net::ERR_IO_PENDING;
-}
+  if (DoomEntriesSince(initial_time))
+    return net::OK;
 
-int BackendImpl::SyncOpenNextEntry(void** iter, Entry** next_entry) {
-  *next_entry = OpenNextEntryImpl(iter);
-  return (*next_entry) ? net::OK : net::ERR_FAILED;
+  return net::ERR_FAILED;
 }
 
-EntryImpl* BackendImpl::OpenNextEntryImpl(void** iter) {
-  return OpenFollowingEntry(true, iter);
+bool BackendImpl::OpenNextEntry(void** iter, Entry** next_entry) {
+  return OpenFollowingEntry(true, iter, next_entry);
 }
 
 int BackendImpl::OpenNextEntry(void** iter, Entry** next_entry,
                                CompletionCallback* callback) {
-  DCHECK(callback);
-  background_queue_.OpenNextEntry(iter, next_entry, callback);
-  return net::ERR_IO_PENDING;
-}
+  if (OpenNextEntry(iter, next_entry))
+    return net::OK;
 
-void BackendImpl::SyncEndEnumeration(void* iter) {
-  scoped_ptr<Rankings::Iterator> iterator(
-      reinterpret_cast<Rankings::Iterator*>(iter));
+  return net::ERR_FAILED;
 }
 
 void BackendImpl::EndEnumeration(void** iter) {
-  background_queue_.EndEnumeration(*iter);
+  scoped_ptr<Rankings::Iterator> iterator(
+      reinterpret_cast<Rankings::Iterator*>(*iter));
   *iter = NULL;
 }
 
@@ -1142,11 +1016,6 @@
   num_refs_ = 0;
 }
 
-int BackendImpl::FlushQueueForTest(CompletionCallback* callback) {
-  background_queue_.FlushQueue(callback);
-  return net::ERR_IO_PENDING;
-}
-
 int BackendImpl::SelfCheck() {
   if (!init_) {
     LOG(ERROR) << "Init failed";
@@ -1167,22 +1036,10 @@
   return CheckAllEntries();
 }
 
-int BackendImpl::SyncOpenPrevEntry(void** iter, Entry** prev_entry) {
-  *prev_entry = OpenPrevEntryImpl(iter);
-  return (*prev_entry) ? net::OK : net::ERR_FAILED;
+bool BackendImpl::OpenPrevEntry(void** iter, Entry** prev_entry) {
+  return OpenFollowingEntry(false, iter, prev_entry);
 }
 
-int BackendImpl::OpenPrevEntry(void** iter, Entry** prev_entry,
-                               CompletionCallback* callback) {
-  DCHECK(callback);
-  background_queue_.OpenPrevEntry(iter, prev_entry, callback);
-  return net::ERR_IO_PENDING;
-}
-
-EntryImpl* BackendImpl::OpenPrevEntryImpl(void** iter) {
-  return OpenFollowingEntry(false, iter);
-}
-
 // ------------------------------------------------------------------------
 
 // We just created a new file so we're going to write the header and set the
@@ -1294,7 +1151,7 @@
   // trying to re-enable the cache.
   if (unit_test_)
     init_ = true;  // Let the destructor do proper cleanup.
-  else if (SyncInit())
+  else if (Init())
     stats_.SetCounter(Stats::FATAL_ERROR, errors + 1);
 }
 
@@ -1444,11 +1301,14 @@
 }
 
 // This is the actual implementation for OpenNextEntry and OpenPrevEntry.
-EntryImpl* BackendImpl::OpenFollowingEntry(bool forward, void** iter) {
+bool BackendImpl::OpenFollowingEntry(bool forward, void** iter,
+                                     Entry** next_entry) {
   if (disabled_)
-    return NULL;
+    return false;
 
   DCHECK(iter);
+  DCHECK(next_entry);
+  *next_entry = NULL;
 
   const int kListsToSearch = 3;
   scoped_refptr<EntryImpl> entries[kListsToSearch];
@@ -1468,7 +1328,7 @@
       entries[i].swap(&temp);  // The entry was already addref'd.
     }
     if (!ret)
-      return NULL;
+      return false;
   } else {
     // Get the next entry from the last list, and the actual entries for the
     // elements on the other lists.
@@ -1504,19 +1364,18 @@
   }
 
   if (newest < 0 || oldest < 0)
-    return NULL;
+    return false;
 
-  EntryImpl* next_entry;
   if (forward) {
-    next_entry = entries[newest].release();
+    entries[newest].swap(reinterpret_cast<EntryImpl**>(next_entry));
     iterator->list = static_cast<Rankings::List>(newest);
   } else {
-    next_entry = entries[oldest].release();
+    entries[oldest].swap(reinterpret_cast<EntryImpl**>(next_entry));
     iterator->list = static_cast<Rankings::List>(oldest);
   }
 
   *iter = iterator.release();
-  return next_entry;
+  return true;
 }
 
 bool BackendImpl::OpenFollowingEntryFromList(bool forward, Rankings::List list,