Support overlapping operations on the SimpleEntryImpl.

net/disk_cache/simple/simple_entry_impl.cc

 // Copyright (c) 2013 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/simple/simple_entry_impl.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/location.h"
@@ skipping 87 matching lines @@
   // SimpleSynchronousEntry, and operations can even happen on them. The files
   // will be removed from the filesystem when they are closed.
   DoomEntry(index_, path_, key_, CompletionCallback());
 #else
   NOTIMPLEMENTED();
 #endif
 }
 
 void SimpleEntryImpl::Close() {
   DCHECK(io_thread_checker_.CalledOnValidThread());
-  Release();  // Balanced in CreationOperationCompleted().
+  // Postpone close operation.
+  // Push the close operation to the end of the line. This way we run all
+  // operations before we are able close.
+  pending_operations_.push(base::Bind(&SimpleEntryImpl::CloseInternal, this));
+  RunNextOperationIfNeeded();
 }
 
 std::string SimpleEntryImpl::GetKey() const {
   DCHECK(io_thread_checker_.CalledOnValidThread());
   return key_;
 }
 
 Time SimpleEntryImpl::GetLastUsed() const {
   DCHECK(io_thread_checker_.CalledOnValidThread());
   return last_used_;
 }
 
 Time SimpleEntryImpl::GetLastModified() const {
   DCHECK(io_thread_checker_.CalledOnValidThread());
   return last_modified_;
 }
 
 int32 SimpleEntryImpl::GetDataSize(int index) const {
   DCHECK(io_thread_checker_.CalledOnValidThread());
   return data_size_[index];
 }
 
 int SimpleEntryImpl::ReadData(int index,
                               int offset,
                               net::IOBuffer* buf,
                               int buf_len,
                               const CompletionCallback& callback) {
   DCHECK(io_thread_checker_.CalledOnValidThread());
-  // TODO(gavinp): Add support for overlapping reads. The net::HttpCache does
-  // make overlapping read requests when multiple transactions access the same
-  // entry as read only. This might make calling SimpleSynchronousEntry::Close()
-  // correctly more tricky (see SimpleEntryImpl::EntryOperationComplete).
-  if (synchronous_entry_in_use_by_worker_) {
-    NOTIMPLEMENTED();
-    CHECK(false);
-  }
-  synchronous_entry_in_use_by_worker_ = true;
-  if (index_)
-    index_->UseIfExists(key_);
-  SynchronousOperationCallback sync_operation_callback =
-      base::Bind(&SimpleEntryImpl::EntryOperationComplete,
-                 this, callback);
-  WorkerPool::PostTask(FROM_HERE,
-                       base::Bind(&SimpleSynchronousEntry::ReadData,
-                                  base::Unretained(synchronous_entry_),
-                                  index, offset, make_scoped_refptr(buf),
-                                  buf_len, sync_operation_callback),
-                       true);
+  if (index < 0 || index >= kSimpleEntryFileCount || buf_len < 0)
+    return net::ERR_INVALID_ARGUMENT;
+  if (offset >= data_size_[index] || offset < 0 || !buf_len)
+    return 0;
+  // TODO(felipeg): Optimization: Add support for truly parallel read
+  // operations.
+  pending_operations_.push(
+      base::Bind(&SimpleEntryImpl::ReadDataInternal,
+                 this,
+                 index,
+                 offset,
+                 make_scoped_refptr(buf),
+                 buf_len,
+                 callback));
+  RunNextOperationIfNeeded();
   return net::ERR_IO_PENDING;
 }
 
 int SimpleEntryImpl::WriteData(int index,
                                int offset,
                                net::IOBuffer* buf,
                                int buf_len,
                                const CompletionCallback& callback,
                                bool truncate) {
   DCHECK(io_thread_checker_.CalledOnValidThread());
-  if (synchronous_entry_in_use_by_worker_) {
-    NOTIMPLEMENTED();
-    CHECK(false);
-  }
-  synchronous_entry_in_use_by_worker_ = true;
-  if (index_)
-    index_->UseIfExists(key_);
-  SynchronousOperationCallback sync_operation_callback =
-      base::Bind(&SimpleEntryImpl::EntryOperationComplete,
-                 this, callback);
-  WorkerPool::PostTask(FROM_HERE,
-                       base::Bind(&SimpleSynchronousEntry::WriteData,
-                                  base::Unretained(synchronous_entry_),
-                                  index, offset, make_scoped_refptr(buf),
-                                  buf_len, sync_operation_callback, truncate),
-                       true);
+  if (index < 0 || index >= kSimpleEntryFileCount || offset < 0 || buf_len < 0)
+    return net::ERR_INVALID_ARGUMENT;
+  pending_operations_.push(
+      base::Bind(&SimpleEntryImpl::WriteDataInternal,
+                 this,
+                 index,
+                 offset,
+                 make_scoped_refptr(buf),
+                 buf_len,
+                 callback,
+                 truncate));
+  RunNextOperationIfNeeded();
+  // TODO(felipeg): Optimization: Add support for optimistic writes, quickly
+  // returning net::OK here.
   return net::ERR_IO_PENDING;
 }
 
 int SimpleEntryImpl::ReadSparseData(int64 offset,
                                     net::IOBuffer* buf,
                                     int buf_len,
                                     const CompletionCallback& callback) {
   DCHECK(io_thread_checker_.CalledOnValidThread());
   // TODO(gavinp): Determine if the simple backend should support sparse data.
   NOTIMPLEMENTED();
@@ skipping 35 matching lines @@
 int SimpleEntryImpl::ReadyForSparseIO(const CompletionCallback& callback) {
   DCHECK(io_thread_checker_.CalledOnValidThread());
   // TODO(gavinp): Determine if the simple backend should support sparse data.
   NOTIMPLEMENTED();
   return net::ERR_FAILED;
 }
 
 SimpleEntryImpl::SimpleEntryImpl(SimpleIndex* index,
                                  const FilePath& path,
                                  const std::string& key)
-    : constructor_thread_(MessageLoopProxy::current()),
-      index_(index->AsWeakPtr()),
-      path_(path),
-      key_(key),
-      synchronous_entry_(NULL),
-      synchronous_entry_in_use_by_worker_(false) {
+    :  index_(index->AsWeakPtr()),
+       path_(path),
+       key_(key),
+       synchronous_entry_(NULL),
+       operation_running_(false) {
 }
 
 SimpleEntryImpl::~SimpleEntryImpl() {
-  if (synchronous_entry_) {
-    base::Closure close_sync_entry =
-        base::Bind(&SimpleSynchronousEntry::Close,
-                   base::Unretained(synchronous_entry_));
-    // We aren't guaranteed to be able to run IO on our constructor thread, but
-    // we are also not guaranteed to be allowed to run WorkerPool::PostTask on
-    // our other threads.
-    if (constructor_thread_->BelongsToCurrentThread())
-      WorkerPool::PostTask(FROM_HERE, close_sync_entry, true);
-    else
-      close_sync_entry.Run();
-  }
+  DCHECK_EQ(0U, pending_operations_.size());
+  DCHECK(!operation_running_);
+}
+
+bool SimpleEntryImpl::RunNextOperationIfNeeded() {
+  DCHECK(io_thread_checker_.CalledOnValidThread());
+  if (pending_operations_.size() <= 0 || operation_running_)
+    return false;
+  base::Closure operation = pending_operations_.front();
+  pending_operations_.pop();
+  operation.Run();
+  return true;
+}
+
+void SimpleEntryImpl::CloseInternal() {
+  DCHECK(io_thread_checker_.CalledOnValidThread());
+  DCHECK(pending_operations_.size() == 0);

[gavinp, 2013/04/19 05:51:39]

Oops.

+  DCHECK(!operation_running_);
+  DCHECK(synchronous_entry_);
+  WorkerPool::PostTask(FROM_HERE,
+                       base::Bind(&SimpleSynchronousEntry::Close,
+                                  base::Unretained(synchronous_entry_)),
+                       true);
+  // Entry::Close() is expected to delete this entry. See disk_cache.h for
+  // details.
+  Release();  // Balanced in CreationOperationCompleted().
+}
+
+void SimpleEntryImpl::ReadDataInternal(int index,
+                                       int offset,
+                                       scoped_refptr<net::IOBuffer> buf,
+                                       int buf_len,
+                                       const CompletionCallback& callback) {
+  DCHECK(io_thread_checker_.CalledOnValidThread());
+  DCHECK(!operation_running_);
+  operation_running_ = true;
+  if (index_)
+    index_->UseIfExists(key_);
+  SynchronousOperationCallback sync_operation_callback =
+      base::Bind(&SimpleEntryImpl::EntryOperationComplete,
+                 this, callback);
+  WorkerPool::PostTask(FROM_HERE,
+                       base::Bind(&SimpleSynchronousEntry::ReadData,
+                                  base::Unretained(synchronous_entry_),
+                                  index, offset, buf,
+                                  buf_len, sync_operation_callback),
+                       true);
+}
+
+void SimpleEntryImpl::WriteDataInternal(int index,
+                                       int offset,
+                                       scoped_refptr<net::IOBuffer> buf,
+                                       int buf_len,
+                                       const CompletionCallback& callback,
+                                       bool truncate) {
+  DCHECK(io_thread_checker_.CalledOnValidThread());
+  DCHECK(!operation_running_);
+  operation_running_ = true;
+  if (index_)
+    index_->UseIfExists(key_);
+
+  // TODO(felipeg): When adding support for optimistic writes we need to set
+  // data_size_[index] = buf_len here.
+  SynchronousOperationCallback sync_operation_callback =
+      base::Bind(&SimpleEntryImpl::EntryOperationComplete,
+                 this, callback);
+  WorkerPool::PostTask(FROM_HERE,
+                       base::Bind(&SimpleSynchronousEntry::WriteData,
+                                  base::Unretained(synchronous_entry_),
+                                  index, offset, buf,
+                                  buf_len, sync_operation_callback, truncate),
+                       true);
 }
 
 void SimpleEntryImpl::CreationOperationComplete(
     Entry** out_entry,
     const CompletionCallback& completion_callback,
     SimpleSynchronousEntry* sync_entry) {
   DCHECK(io_thread_checker_.CalledOnValidThread());
   if (!sync_entry) {
     completion_callback.Run(net::ERR_FAILED);
     // If OpenEntry failed, we must remove it from our index.
     if (index_)
       index_->Remove(key_);
     // The reference held by the Callback calling us will go out of scope and
     // delete |this| on leaving this scope.
     return;
   }
   // The Backend interface requires us to return |this|, and keep the Entry
   // alive until Entry::Close(). Adding a reference to self will keep |this|
   // alive after the scope of the Callback calling us is destroyed.
-  AddRef();  // Balanced in Close().
+  AddRef();  // Balanced in CloseInternal().
   synchronous_entry_ = sync_entry;
   SetSynchronousData();
   if (index_)
     index_->Insert(key_);
   *out_entry = this;
   completion_callback.Run(net::OK);
 }
 
 void SimpleEntryImpl::EntryOperationComplete(
     const CompletionCallback& completion_callback,
     int result) {
   DCHECK(io_thread_checker_.CalledOnValidThread());
   DCHECK(synchronous_entry_);
-  DCHECK(synchronous_entry_in_use_by_worker_);
-  synchronous_entry_in_use_by_worker_ = false;
+  DCHECK(operation_running_);
+
+  operation_running_ = false;
   SetSynchronousData();
   if (index_) {
     if (result >= 0) {
       index_->UpdateEntrySize(synchronous_entry_->key(),
                               synchronous_entry_->GetFileSize());
     } else {
       index_->Remove(synchronous_entry_->key());
     }
   }
   completion_callback.Run(result);
+  RunNextOperationIfNeeded();
 }
 
 void SimpleEntryImpl::SetSynchronousData() {
   DCHECK(io_thread_checker_.CalledOnValidThread());
-  DCHECK(!synchronous_entry_in_use_by_worker_);
+  DCHECK(!operation_running_);
   // TODO(felipeg): These copies to avoid data races are not optimal. While
   // adding an IO thread index (for fast misses etc...), we can store this data
   // in that structure. This also solves problems with last_used() on ext4
   // filesystems not being accurate.
   last_used_ = synchronous_entry_->last_used();
   last_modified_ = synchronous_entry_->last_modified();
   for (int i = 0; i < kSimpleEntryFileCount; ++i)
     data_size_[i] = synchronous_entry_->data_size(i);
 }
 
 }  // namespace disk_cache