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

net/disk_cache/entry_impl.cc

Index: net/disk_cache/entry_impl.cc
===================================================================
--- net/disk_cache/entry_impl.cc	(revision 126788)
+++ net/disk_cache/entry_impl.cc	(working copy)
@@ -106,7 +106,7 @@
   void Truncate(int offset);
 
   // Writes |len| bytes from |buf| at the given |offset|.
-  void Write(int offset, net::IOBuffer* buf, int len);
+  void Write(int offset, IOBuffer* buf, int len);
 
   // Returns true if we can read |len| bytes from |offset|, given that the
   // actual file has |eof| bytes stored. Note that the number of bytes to read
@@ -115,7 +115,7 @@
   bool PreRead(int eof, int offset, int* len);
 
   // Read |len| bytes from |buf| at the given |offset|.
-  int Read(int offset, net::IOBuffer* buf, int len);
+  int Read(int offset, IOBuffer* buf, int len);
 
   // Prepare this buffer for reuse.
   void Reset();
@@ -168,7 +168,7 @@
     buffer_.resize(offset);
 }
 
-void EntryImpl::UserBuffer::Write(int offset, net::IOBuffer* buf, int len) {
+void EntryImpl::UserBuffer::Write(int offset, IOBuffer* buf, int len) {
   DCHECK_GE(offset, 0);
   DCHECK_GE(len, 0);
   DCHECK_GE(offset + len, 0);
@@ -225,7 +225,7 @@
   return (offset - offset_ < Size());
 }
 
-int EntryImpl::UserBuffer::Read(int offset, net::IOBuffer* buf, int len) {
+int EntryImpl::UserBuffer::Read(int offset, IOBuffer* buf, int len) {
   DCHECK_GE(offset, 0);
   DCHECK_GT(len, 0);
   DCHECK(Size() || offset < offset_);
@@ -292,8 +292,9 @@
 // ------------------------------------------------------------------------
 
 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;
@@ -301,16 +302,15 @@
 }
 
 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) {
+int EntryImpl::ReadDataImpl(int index, int offset, IOBuffer* buf, int buf_len,
+                            const CompletionCallback& callback) {
   if (net_log_.IsLoggingAllEvents()) {
     net_log_.BeginEvent(
         net::NetLog::TYPE_ENTRY_READ_DATA,
@@ -328,9 +328,9 @@
   return result;
 }
 
-int EntryImpl::WriteDataImpl(
-    int index, int offset, net::IOBuffer* buf, int buf_len,
-    const net::CompletionCallback& callback, bool truncate) {
+int EntryImpl::WriteDataImpl(int index, int offset, IOBuffer* buf, int buf_len,
+                             const CompletionCallback& callback,
+                             bool truncate) {
   if (net_log_.IsLoggingAllEvents()) {
     net_log_.BeginEvent(
         net::NetLog::TYPE_ENTRY_WRITE_DATA,
@@ -349,8 +349,8 @@
   return result;
 }
 
-int EntryImpl::ReadSparseDataImpl(int64 offset, net::IOBuffer* buf, int buf_len,
-                                  const net::CompletionCallback& callback) {
+int EntryImpl::ReadSparseDataImpl(int64 offset, IOBuffer* buf, int buf_len,
+                                  const CompletionCallback& callback) {
   DCHECK(node_.Data()->dirty || read_only_);
   int result = InitSparseData();
   if (net::OK != result)
@@ -363,9 +363,8 @@
   return result;
 }
 
-int EntryImpl::WriteSparseDataImpl(
-    int64 offset, net::IOBuffer* buf, int buf_len,
-    const net::CompletionCallback& callback) {
+int EntryImpl::WriteSparseDataImpl(int64 offset, IOBuffer* buf, int buf_len,
+                                   const CompletionCallback& callback) {
   DCHECK(node_.Data()->dirty || read_only_);
   int result = InitSparseData();
   if (net::OK != result)
@@ -393,7 +392,7 @@
   sparse_->CancelIO();
 }
 
-int EntryImpl::ReadyForSparseIOImpl(const net::CompletionCallback& callback) {
+int EntryImpl::ReadyForSparseIOImpl(const CompletionCallback& callback) {
   DCHECK(sparse_.get());
   return sparse_->ReadyToUse(callback);
 }
@@ -678,9 +677,15 @@
 }
 
 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();
@@ -688,6 +693,9 @@
 }
 
 void EntryImpl::ReportIOTime(Operation op, const base::TimeTicks& start) {
+  if (!backend_)
+    return;
+
   int group = backend_->GetSizeGroup();
   switch (op) {
     case kRead:
@@ -744,11 +752,13 @@
 // ------------------------------------------------------------------------
 
 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 {
@@ -801,8 +811,8 @@
   return entry->Data()->data_size[index];
 }
 
-int EntryImpl::ReadData(int index, int offset, net::IOBuffer* buf, int buf_len,
-                        const net::CompletionCallback& callback) {
+int EntryImpl::ReadData(int index, int offset, IOBuffer* buf, int buf_len,
+                        const CompletionCallback& callback) {
   if (callback.is_null())
     return ReadDataImpl(index, offset, buf, buf_len, callback);
 
@@ -817,14 +827,15 @@
   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) {
+int EntryImpl::WriteData(int index, int offset, IOBuffer* buf, int buf_len,
+                         const CompletionCallback& callback, bool truncate) {
   if (callback.is_null())
     return WriteDataImpl(index, offset, buf, buf_len, callback, truncate);
 
@@ -835,35 +846,44 @@
   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) {
+int EntryImpl::ReadSparseData(int64 offset, IOBuffer* buf, int buf_len,
+                              const 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) {
+int EntryImpl::WriteSparseData(int64 offset, IOBuffer* buf, int buf_len,
+                               const 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);
+                                 const CompletionCallback& callback) {
+  if (!background_queue_)
+    return net::ERR_UNEXPECTED;
+
+  background_queue_->GetAvailableRange(this, offset, len, start, callback);
   return net::ERR_IO_PENDING;
 }
 
@@ -877,14 +897,18 @@
 }
 
 void EntryImpl::CancelSparseIO() {
-  backend_->background_queue()->CancelSparseIO(this);
+  if (background_queue_)
+    background_queue_->CancelSparseIO(this);
 }
 
-int EntryImpl::ReadyForSparseIO(const net::CompletionCallback& callback) {
+int EntryImpl::ReadyForSparseIO(const 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;
 }
 
@@ -896,6 +920,11 @@
 // written before).
 EntryImpl::~EntryImpl() {
   Log("~EntryImpl in");
+  if (!backend_) {
+    entry_.clear_modified();
+    node_.clear_modified();
+    return;
+  }
 
   // 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
@@ -943,9 +972,9 @@
 
 // ------------------------------------------------------------------------
 
-int EntryImpl::InternalReadData(
-    int index, int offset, net::IOBuffer* buf, int buf_len,
-    const net::CompletionCallback& callback) {
+int EntryImpl::InternalReadData(int index, int offset,
+                                IOBuffer* buf, int buf_len,
+                                const CompletionCallback& callback) {
   DCHECK(node_.Data()->dirty || read_only_);
   DVLOG(2) << "Read from " << index << " at " << offset << " : " << buf_len;
   if (index < 0 || index >= kNumStreams)
@@ -958,6 +987,9 @@
   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)
@@ -1024,9 +1056,10 @@
   return (completed || callback.is_null()) ? buf_len : net::ERR_IO_PENDING;
 }
 
-int EntryImpl::InternalWriteData(
-    int index, int offset, net::IOBuffer* buf, int buf_len,
-    const net::CompletionCallback& callback, bool truncate) {
+int EntryImpl::InternalWriteData(int index, int offset,
+                                 IOBuffer* buf, int buf_len,
+                                 const CompletionCallback& callback,
+                                 bool truncate) {
   DCHECK(node_.Data()->dirty || read_only_);
   DVLOG(2) << "Write to " << index << " at " << offset << " : " << buf_len;
   if (index < 0 || index >= kNumStreams)
@@ -1035,6 +1068,9 @@
   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.
@@ -1140,6 +1176,8 @@
 
 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) {
@@ -1164,6 +1202,7 @@
 // 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()) {
@@ -1181,6 +1220,9 @@
 }
 
 void EntryImpl::UpdateRank(bool modified) {
+  if (!backend_)
+    return;
+
   if (!doomed_) {
     // Everything is handled by the backend.
     backend_->UpdateRank(this, modified);
@@ -1195,6 +1237,9 @@
 }
 
 File* EntryImpl::GetBackingFile(Addr address, int index) {
+  if (!backend_)
+    return NULL;
+
   File* file;
   if (address.is_separate_file())
     file = GetExternalFile(address, index);
@@ -1466,6 +1511,7 @@
 }
 
 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.