Support overlapping operations on the SimpleEntryImpl.

net/disk_cache/simple/simple_entry_impl.cc

Index: net/disk_cache/simple/simple_entry_impl.cc
diff --git a/net/disk_cache/simple/simple_entry_impl.cc b/net/disk_cache/simple/simple_entry_impl.cc
index 1917a88715091ac1a37be9dae3b8fd104b6f4edf..580caf5d4c9a2c35a815c4e51de59f7b8481915b 100644
--- a/net/disk_cache/simple/simple_entry_impl.cc
+++ b/net/disk_cache/simple/simple_entry_impl.cc
@@ -88,6 +88,7 @@ int SimpleEntryImpl::DoomEntry(WeakPtr<SimpleIndex> index,
 
 void SimpleEntryImpl::Doom() {
   DCHECK(io_thread_checker_.CalledOnValidThread());
+  DCHECK(!operation_running_);
 #if defined(OS_POSIX)
   // This call to static SimpleEntryImpl::DoomEntry() will just erase the
   // underlying files. On POSIX, this is fine; the files are still open on the
@@ -101,12 +102,22 @@ void SimpleEntryImpl::Doom() {
 
 void SimpleEntryImpl::Close() {
   DCHECK(io_thread_checker_.CalledOnValidThread());
-  if (!synchronous_entry_in_use_by_worker_) {
-    WorkerPool::PostTask(FROM_HERE,
-                         base::Bind(&SimpleSynchronousEntry::Close,
-                                    base::Unretained(synchronous_entry_)),
-                         true);
+  if (operation_running_) {
+    // 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::Close,
+                   weak_ptr_factory_.GetWeakPtr()));
+    return;

[pasko-google - do not use, 2013/04/17 15:14:46]

since it is not a trivial if->return case, would be more readable to have if
(operation_running_) else { ... }

[felipeg, 2013/04/17 15:53:57]

Done.

   }
+  DCHECK(pending_operations_.size() == 0);
+  DCHECK(!operation_running_);
+
+  WorkerPool::PostTask(FROM_HERE,
+                       base::Bind(&SimpleSynchronousEntry::Close,
+                                  base::Unretained(synchronous_entry_)),
+                       true);
   // Entry::Close() is expected to release this entry. See disk_cache.h for
   // details.
   delete this;
@@ -138,27 +149,21 @@ int SimpleEntryImpl::ReadData(int index,
                               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,
-                 index_, callback, weak_ptr_factory_.GetWeakPtr(),
-                 synchronous_entry_);
-  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)

[pasko-google - do not use, 2013/04/17 15:14:46]

was this requested by tests?
Otherwise seems like DCHECK would fail earlier and make it easier to
investigate.

[felipeg, 2013/04/17 15:53:57]

Done.

+    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,
+                 weak_ptr_factory_.GetWeakPtr(),
+                 index,
+                 offset,
+                 make_scoped_refptr(buf),
+                 buf_len,
+                 callback));
+  RunNextOperationIfNeeded();
   return net::ERR_IO_PENDING;
 }
 
@@ -169,23 +174,22 @@ int SimpleEntryImpl::WriteData(int index,
                                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,
-                 index_, callback, weak_ptr_factory_.GetWeakPtr(),
-                 synchronous_entry_);
-  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,
+                 weak_ptr_factory_.GetWeakPtr(),
+                 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;
 }
 
@@ -245,7 +249,7 @@ SimpleEntryImpl::SimpleEntryImpl(
       path_(synchronous_entry->path()),
       key_(synchronous_entry->key()),
       synchronous_entry_(synchronous_entry),
-      synchronous_entry_in_use_by_worker_(false),
+      operation_running_(false),
       index_(index) {
   DCHECK(synchronous_entry);
   SetSynchronousData();
@@ -255,6 +259,66 @@ SimpleEntryImpl::~SimpleEntryImpl() {
   DCHECK(io_thread_checker_.CalledOnValidThread());
 }
 
+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::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,
+                 index_, callback, weak_ptr_factory_.GetWeakPtr(),
+                 synchronous_entry_);
+  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_);
+
+  last_used_ = base::Time::Now();
+  last_modified_ = base::Time::Now();
+  data_size_[index] = buf_len;
+
+  SynchronousOperationCallback sync_operation_callback =
+      base::Bind(&SimpleEntryImpl::EntryOperationComplete,
+                 index_, callback, weak_ptr_factory_.GetWeakPtr(),
+                 synchronous_entry_);
+  WorkerPool::PostTask(FROM_HERE,
+                       base::Bind(&SimpleSynchronousEntry::WriteData,
+                                  base::Unretained(synchronous_entry_),
+                                  index, offset, buf,
+                                  buf_len, sync_operation_callback, truncate),
+                       true);
+}
+
 // static
 void SimpleEntryImpl::CreationOperationComplete(
     WeakPtr<SimpleIndex> index,
@@ -291,9 +355,10 @@ void SimpleEntryImpl::EntryOperationComplete(
   }
 
   if (entry) {
-    DCHECK(entry->synchronous_entry_in_use_by_worker_);
-    entry->synchronous_entry_in_use_by_worker_ = false;
+    DCHECK(entry->operation_running_);
+    entry->operation_running_ = false;
     entry->SetSynchronousData();
+    entry->RunNextOperationIfNeeded();
   } else {
     // |entry| must have had Close() called while this operation was in flight.
     // Since the simple cache now only supports one pending entry operation in
@@ -308,7 +373,7 @@ void SimpleEntryImpl::EntryOperationComplete(
 
 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