Disk cache: Remove all non essential synchronization from the cache destructor.

net/disk_cache/entry_impl.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 "net/disk_cache/entry_impl.h"
 
 #include "base/message_loop.h"
 #include "base/metrics/histogram.h"
 #include "base/string_util.h"
 #include "net/base/io_buffer.h"
@@ skipping 274 matching lines @@
 
   DVLOG(3) << "Buffer grow to " << required;
 
   buffer_.reserve(required);
   return true;
 }
 
 // ------------------------------------------------------------------------
 
 EntryImpl::EntryImpl(BackendImpl* backend, Addr address, bool read_only)
-    : entry_(NULL, Addr(0)), node_(NULL, Addr(0)), backend_(backend),
-      doomed_(false), read_only_(read_only), dirty_(false) {
+    : entry_(NULL, Addr(0)), node_(NULL, Addr(0)),
+      backend_(backend->GetWeakPtr()), doomed_(false), read_only_(read_only),
+      dirty_(false) {
   entry_.LazyInit(backend->File(address), address);
   for (int i = 0; i < kNumStreams; i++) {
     unreported_size_[i] = 0;
   }
 }
 
 void EntryImpl::DoomImpl() {
-  if (doomed_)
+  if (doomed_ || !backend_)
     return;
 
   SetPointerForInvalidEntry(backend_->GetCurrentEntryId());
   backend_->InternalDoomEntry(this);
 }
 
 int EntryImpl::ReadDataImpl(
     int index, int offset, net::IOBuffer* buf, int buf_len,
     const net::CompletionCallback& callback) {
   if (net_log_.IsLoggingAllEvents()) {
@@ skipping 356 matching lines @@
       stored->data_size[i] = 0;
   }
   entry_.Store();
 }
 
 void EntryImpl::IncrementIoCount() {
   backend_->IncrementIoCount();
 }
 
 void EntryImpl::DecrementIoCount() {
-  backend_->DecrementIoCount();
+  if (backend_)
+    backend_->DecrementIoCount();
+}
+
+void EntryImpl::OnEntryCreated(BackendImpl* backend) {
+  // Just grab a reference to the backround queue.
+  background_queue_ = backend->GetBackgroundQueue();
 }
 
 void EntryImpl::SetTimes(base::Time last_used, base::Time last_modified) {
   node_.Data()->last_used = last_used.ToInternalValue();
   node_.Data()->last_modified = last_modified.ToInternalValue();
   node_.set_modified();
 }
 
 void EntryImpl::ReportIOTime(Operation op, const base::TimeTicks& start) {
+  if (!backend_)
+    return;
+
   int group = backend_->GetSizeGroup();
   switch (op) {
     case kRead:
       CACHE_UMA(AGE_MS, "ReadTime", group, start);
       break;
     case kWrite:
       CACHE_UMA(AGE_MS, "WriteTime", group, start);
       break;
     case kSparseRead:
       CACHE_UMA(AGE_MS, "SparseReadTime", 0, start);
@@ skipping 36 matching lines @@
 
   if (key_size < key1_len || key_size > kMaxInternalKeyLength)
     return 1;
 
   return ((key_size - key1_len) / 256 + 2);
 }
 
 // ------------------------------------------------------------------------
 
 void EntryImpl::Doom() {
-  backend_->background_queue()->DoomEntryImpl(this);
+  if (background_queue_)
+    background_queue_->DoomEntryImpl(this);
 }
 
 void EntryImpl::Close() {
-  backend_->background_queue()->CloseEntryImpl(this);
+  if (background_queue_)
+    background_queue_->CloseEntryImpl(this);
 }
 
 std::string EntryImpl::GetKey() const {
   CacheEntryBlock* entry = const_cast<CacheEntryBlock*>(&entry_);
   int key_len = entry->Data()->key_len;
   if (key_len <= kMaxInternalKeyLength)
     return std::string(entry->Data()->key);
 
   // We keep a copy of the key so that we can always return it, even if the
   // backend is disabled.
@@ skipping 48 matching lines @@
   if (index < 0 || index >= kNumStreams)
     return net::ERR_INVALID_ARGUMENT;
 
   int entry_size = entry_.Data()->data_size[index];
   if (offset >= entry_size || offset < 0 || !buf_len)
     return 0;
 
   if (buf_len < 0)
     return net::ERR_INVALID_ARGUMENT;
 
-  backend_->background_queue()->ReadData(this, index, offset, buf, buf_len,
-                                         callback);
+  if (!background_queue_)
+    return net::ERR_UNEXPECTED;
+
+  background_queue_->ReadData(this, index, offset, buf, buf_len, callback);
   return net::ERR_IO_PENDING;
 }
 
 int EntryImpl::WriteData(
     int index, int offset, net::IOBuffer* buf, int buf_len,
     const net::CompletionCallback& callback, bool truncate) {
   if (callback.is_null())
     return WriteDataImpl(index, offset, buf, buf_len, callback, truncate);
 
   DCHECK(node_.Data()->dirty || read_only_);
   if (index < 0 || index >= kNumStreams)
     return net::ERR_INVALID_ARGUMENT;
 
   if (offset < 0 || buf_len < 0)
     return net::ERR_INVALID_ARGUMENT;
 
-  backend_->background_queue()->WriteData(this, index, offset, buf, buf_len,
-                                          truncate, callback);
+  if (!background_queue_)
+    return net::ERR_UNEXPECTED;
+
+  background_queue_->WriteData(this, index, offset, buf, buf_len, truncate,
+                               callback);
   return net::ERR_IO_PENDING;
 }
 
 int EntryImpl::ReadSparseData(int64 offset, net::IOBuffer* buf, int buf_len,
                               const net::CompletionCallback& callback) {
   if (callback.is_null())
     return ReadSparseDataImpl(offset, buf, buf_len, callback);
 
-  backend_->background_queue()->ReadSparseData(this, offset, buf, buf_len,
-                                               callback);
+  if (!background_queue_)
+    return net::ERR_UNEXPECTED;
+
+  background_queue_->ReadSparseData(this, offset, buf, buf_len, callback);
   return net::ERR_IO_PENDING;
 }
 
 int EntryImpl::WriteSparseData(int64 offset, net::IOBuffer* buf, int buf_len,
                                const net::CompletionCallback& callback) {
   if (callback.is_null())
     return WriteSparseDataImpl(offset, buf, buf_len, callback);
 
-  backend_->background_queue()->WriteSparseData(this, offset, buf, buf_len,
-                                                callback);
+  if (!background_queue_)
+    return net::ERR_UNEXPECTED;
+
+  background_queue_->WriteSparseData(this, offset, buf, buf_len, callback);
   return net::ERR_IO_PENDING;
 }
 
 int EntryImpl::GetAvailableRange(int64 offset, int len, int64* start,
                                  const net::CompletionCallback& callback) {
-  backend_->background_queue()->GetAvailableRange(this, offset, len, start,
-                                                  callback);
+  if (!background_queue_)
+    return net::ERR_UNEXPECTED;
+
+  background_queue_->GetAvailableRange(this, offset, len, start, callback);
   return net::ERR_IO_PENDING;
 }
 
 bool EntryImpl::CouldBeSparse() const {
   if (sparse_.get())
     return true;
 
   scoped_ptr<SparseControl> sparse;
   sparse.reset(new SparseControl(const_cast<EntryImpl*>(this)));
   return sparse->CouldBeSparse();
 }
 
 void EntryImpl::CancelSparseIO() {
-  backend_->background_queue()->CancelSparseIO(this);
+  if (background_queue_)
+    background_queue_->CancelSparseIO(this);
 }
 
 int EntryImpl::ReadyForSparseIO(const net::CompletionCallback& callback) {
   if (!sparse_.get())
     return net::OK;
 
-  backend_->background_queue()->ReadyForSparseIO(this, callback);
+  if (!background_queue_)
+    return net::ERR_UNEXPECTED;
+
+  background_queue_->ReadyForSparseIO(this, callback);
   return net::ERR_IO_PENDING;
 }
 
 // When an entry is deleted from the cache, we clean up all the data associated
 // with it for two reasons: to simplify the reuse of the block (we know that any
 // unused block is filled with zeros), and to simplify the handling of write /
 // read partial information from an entry (don't have to worry about returning
 // data related to a previous cache entry because the range was not fully
 // written before).
 EntryImpl::~EntryImpl() {
+  if (!backend_) {
+    entry_.clear_modified();
+    node_.clear_modified();
+    return;
+  }
   Log("~EntryImpl in");
 
   // Save the sparse info to disk. This will generate IO for this entry and
   // maybe for a child entry, so it is important to do it before deleting this
   // entry.
   sparse_.reset();
 
   // Remove this entry from the list of open entries.
   backend_->OnEntryDestroyBegin(entry_.address());
 
@@ skipping 43 matching lines @@
   if (index < 0 || index >= kNumStreams)
     return net::ERR_INVALID_ARGUMENT;
 
   int entry_size = entry_.Data()->data_size[index];
   if (offset >= entry_size || offset < 0 || !buf_len)
     return 0;
 
   if (buf_len < 0)
     return net::ERR_INVALID_ARGUMENT;
 
+  if (!backend_)
+    return net::ERR_UNEXPECTED;
+
   TimeTicks start = TimeTicks::Now();
 
   if (offset + buf_len > entry_size)
     buf_len = entry_size - offset;
 
   UpdateRank(false);
 
   backend_->OnEvent(Stats::READ_DATA);
   backend_->OnRead(buf_len);
 
@@ skipping 57 matching lines @@
     int index, int offset, net::IOBuffer* buf, int buf_len,
     const net::CompletionCallback& callback, bool truncate) {
   DCHECK(node_.Data()->dirty || read_only_);
   DVLOG(2) << "Write to " << index << " at " << offset << " : " << buf_len;
   if (index < 0 || index >= kNumStreams)
     return net::ERR_INVALID_ARGUMENT;
 
   if (offset < 0 || buf_len < 0)
     return net::ERR_INVALID_ARGUMENT;
 
+  if (!backend_)
+    return net::ERR_UNEXPECTED;
+
   int max_file_size = backend_->MaxFileSize();
 
   // offset or buf_len could be negative numbers.
   if (offset > max_file_size || buf_len > max_file_size ||
       offset + buf_len > max_file_size) {
     int size = offset + buf_len;
     if (size <= max_file_size)
       size = kint32max;
     backend_->TooMuchStorageRequested(size);
     return net::ERR_FAILED;
@@ skipping 85 matching lines @@
   if (!CreateBlock(size, &address))
     return false;
 
   entry_.Data()->data_addr[index] = address.value();
   entry_.Store();
   return true;
 }
 
 bool EntryImpl::CreateBlock(int size, Addr* address) {
   DCHECK(!address->is_initialized());
+  if (!backend_)
+    return false;
 
   FileType file_type = Addr::RequiredFileType(size);
   if (EXTERNAL == file_type) {
     if (size > backend_->MaxFileSize())
       return false;
     if (!backend_->CreateExternalFile(address))
       return false;
   } else {
     int num_blocks = (size + Addr::BlockSizeForFileType(file_type) - 1) /
                      Addr::BlockSizeForFileType(file_type);
 
     if (!backend_->CreateBlock(file_type, num_blocks, address))
       return false;
   }
   return true;
 }
 
 // Note that this method may end up modifying a block file so upon return the
 // involved block will be free, and could be reused for something else. If there
 // is a crash after that point (and maybe before returning to the caller), the
 // entry will be left dirty... and at some point it will be discarded; it is
 // important that the entry doesn't keep a reference to this address, or we'll
 // end up deleting the contents of |address| once again.
 void EntryImpl::DeleteData(Addr address, int index) {
+  DCHECK(backend_);
   if (!address.is_initialized())
     return;
   if (address.is_separate_file()) {
     int failure = !DeleteCacheFile(backend_->GetFileName(address));
     CACHE_UMA(COUNTS, "DeleteFailed", 0, failure);
     if (failure) {
       LOG(ERROR) << "Failed to delete " <<
           backend_->GetFileName(address).value() << " from the cache.";
     }
     if (files_[index])
       files_[index] = NULL;  // Releases the object.
   } else {
     backend_->DeleteBlock(address, true);
   }
 }
 
 void EntryImpl::UpdateRank(bool modified) {
+  if (!backend_)
+    return;
+
   if (!doomed_) {
     // Everything is handled by the backend.
     backend_->UpdateRank(this, modified);
     return;
   }
 
   Time current = Time::Now();
   node_.Data()->last_used = current.ToInternalValue();
 
   if (modified)
     node_.Data()->last_modified = current.ToInternalValue();
 }
 
 File* EntryImpl::GetBackingFile(Addr address, int index) {
+  if (!backend_)
+    return NULL;
+
   File* file;
   if (address.is_separate_file())
     file = GetExternalFile(address, index);
   else
     file = backend_->File(address);
   return file;
 }
 
 File* EntryImpl::GetExternalFile(Addr address, int index) {
   DCHECK(index >= 0 && index <= kKeyFileIndex);
@@ skipping 251 matching lines @@
 void EntryImpl::SetEntryFlags(uint32 flags) {
   entry_.Data()->flags |= flags;
   entry_.set_modified();
 }
 
 uint32 EntryImpl::GetEntryFlags() {
   return entry_.Data()->flags;
 }
 
 void EntryImpl::GetData(int index, char** buffer, Addr* address) {
+  DCHECK(backend_);
   if (user_buffers_[index].get() && user_buffers_[index]->Size() &&
       !user_buffers_[index]->Start()) {
     // The data is already in memory, just copy it and we're done.
     int data_len = entry_.Data()->data_size[index];
     if (data_len <= user_buffers_[index]->Size()) {
       DCHECK(!user_buffers_[index]->Start());
       *buffer = new char[data_len];
       memcpy(*buffer, user_buffers_[index]->Data(), data_len);
       return;
     }
@@ skipping 21 matching lines @@
   Trace("%s 0x%p 0x%x 0x%x", msg, reinterpret_cast<void*>(this),
         entry_.address().value(), node_.address().value());
 
   Trace("  data: 0x%x 0x%x 0x%x", entry_.Data()->data_addr[0],
         entry_.Data()->data_addr[1], entry_.Data()->long_key);
 
   Trace("  doomed: %d 0x%x", doomed_, dirty);
 }
 
 }  // namespace disk_cache