Persist sessionStorage on disk.

webkit/dom_storage/dom_storage_area.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 "webkit/dom_storage/dom_storage_area.h"
 
 #include "base/bind.h"
-#include "base/file_util.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/time.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebString.h"
 #include "webkit/database/database_util.h"
 #include "webkit/dom_storage/dom_storage_map.h"
 #include "webkit/dom_storage/dom_storage_namespace.h"
 #include "webkit/dom_storage/dom_storage_task_runner.h"
 #include "webkit/dom_storage/dom_storage_types.h"
+#include "webkit/dom_storage/local_storage_database_adapter.h"
+#include "webkit/dom_storage/session_storage_database.h"
+#include "webkit/dom_storage/session_storage_database_adapter.h"
 #include "webkit/fileapi/file_system_util.h"
 #include "webkit/glue/webkit_glue.h"
 
 using webkit_database::DatabaseUtil;
 
 namespace dom_storage {
 
 static const int kCommitTimerSeconds = 1;
 
 DomStorageArea::CommitBatch::CommitBatch()
@@ skipping 27 matching lines @@
 DomStorageArea::DomStorageArea(
     int64 namespace_id, const GURL& origin,
     const FilePath& directory, DomStorageTaskRunner* task_runner)
     : namespace_id_(namespace_id), origin_(origin),
       directory_(directory),
       task_runner_(task_runner),
       map_(new DomStorageMap(kPerAreaQuota)),
       is_initial_import_done_(true),
       is_shutdown_(false),
       commit_batches_in_flight_(0) {
-  if (namespace_id == kLocalStorageNamespaceId && !directory.empty()) {
+  DCHECK_EQ(kLocalStorageNamespaceId, namespace_id);
+  if (!directory.empty()) {
     FilePath path = directory.Append(DatabaseFileNameFromOrigin(origin_));
-    backing_.reset(new DomStorageDatabase(path));
+    backing_.reset(new LocalStorageDatabaseAdapter(path));
     is_initial_import_done_ = false;
   }
 }
+
+DomStorageArea::DomStorageArea(
+    int64 namespace_id, const GURL& origin,
+    SessionStorageDatabase* session_storage_backing,
+    DomStorageTaskRunner* task_runner)
+    : namespace_id_(namespace_id), origin_(origin),
+      task_runner_(task_runner),
+      map_(new DomStorageMap(kPerAreaQuota)),
+      session_storage_backing_(session_storage_backing),
+      is_initial_import_done_(true),
+      is_shutdown_(false),
+      commit_batches_in_flight_(0) {
+  DCHECK(namespace_id != kLocalStorageNamespaceId);
+  if (session_storage_backing) {
+    backing_.reset(new SessionStorageDatabaseAdapter(
+        session_storage_backing, namespace_id, origin));
+    is_initial_import_done_ = false;
+  }
+}
 
 DomStorageArea::~DomStorageArea() {
 }
 
 void DomStorageArea::ExtractValues(ValuesMap* map) {
   if (is_shutdown_)
     return;
   InitialImportIfNeeded();
   map_->ExtractValues(map);
 }
@@ skipping 63 matching lines @@
     commit_batch->clear_all_first = true;
     commit_batch->changed_values.clear();
   }
 
   return true;
 }
 
 DomStorageArea* DomStorageArea::ShallowCopy(int64 destination_namespace_id) {
   DCHECK_NE(kLocalStorageNamespaceId, namespace_id_);
   DCHECK_NE(kLocalStorageNamespaceId, destination_namespace_id);
-  DCHECK(!backing_.get());  // SessionNamespaces aren't stored on disk.
 
-  DomStorageArea* copy = new DomStorageArea(destination_namespace_id, origin_,
-                                            FilePath(), task_runner_);
+  DomStorageArea* copy = new DomStorageArea(
+      destination_namespace_id, origin_, session_storage_backing_,
+      task_runner_);
   copy->map_ = map_;
   copy->is_shutdown_ = is_shutdown_;
+
+  // All the uncommitted changes to this area need to happen before the actual

[michaeln, 2012/05/16 08:10:55]

really nice simplifications to this file compared to prior snapshots!

+  // shallow copy is made (scheduled by the upper layer). Another OnCommitTimer
+  // call might be in the event queue at this point, but it's handled gracefully
+  // when it fires.
+  if (commit_batch_.get())
+    OnCommitTimer();
   return copy;
 }
 
 bool DomStorageArea::HasUncommittedChanges() const {
   DCHECK(!is_shutdown_);
   return commit_batch_.get() || commit_batches_in_flight_;
 }
 
 void DomStorageArea::DeleteOrigin() {
   DCHECK(!is_shutdown_);
   if (HasUncommittedChanges()) {
     // TODO(michaeln): This logically deletes the data immediately,
     // and in a matter of a second, deletes the rows from the backing
     // database file, but the file itself will linger until shutdown
     // or purge time. Ideally, this should delete the file more
     // quickly.
     Clear();
     return;
   }
   map_ = new DomStorageMap(kPerAreaQuota);
-  if (backing_.get()) {
+  if (backing_.get() && !session_storage_backing_.get()) {
+    // This is localStorage.
     is_initial_import_done_ = false;
-    backing_.reset(new DomStorageDatabase(backing_->file_path()));
-    file_util::Delete(backing_->file_path(), false);
-    file_util::Delete(
-        DomStorageDatabase::GetJournalFilePath(backing_->file_path()), false);
+    backing_->Reset();
+    backing_->DeleteFiles();
+  } else if (session_storage_backing_.get()) {

[michaeln, 2012/05/16 08:10:55]

should is_initial_import_done_ = true be set here?

[marja, 2012/05/25 13:04:06]

Do you mean is_initial_import_done_ = false, like above?

[michaeln, 2012/05/30 01:29:19]

I actually meant 'true'. Suppose RemoveItem() is called prior to the DeleteArea
tasks having been run on the commit sequence. If that flag is 'false', we'll
read from the db values that have been logically deleted.

[marja, 2012/05/30 11:46:19]

Done. I was confused, = true makes sense. But why does the above have = false?
The db is empty, so there is nothing to import..

+    task_runner_->PostShutdownBlockingTask(
+        FROM_HERE,
+        DomStorageTaskRunner::COMMIT_SEQUENCE,
+        base::Bind(&SessionStorageDatabase::DeleteArea,
+                   session_storage_backing_.get(),
+                   namespace_id_, origin_));
   }
 }
 
 void DomStorageArea::PurgeMemory() {
   DCHECK(!is_shutdown_);
   if (!is_initial_import_done_ ||  // We're not using any memory.
       !backing_.get() ||  // We can't purge anything.
       HasUncommittedChanges())  // We leave things alone with changes pending.
     return;
 
   // Drop the in memory cache, we'll reload when needed.
   is_initial_import_done_ = false;
   map_ = new DomStorageMap(kPerAreaQuota);
 
   // Recreate the database object, this frees up the open sqlite connection
   // and its page cache.
-  backing_.reset(new DomStorageDatabase(backing_->file_path()));
+  backing_->Reset();
 }
 
 void DomStorageArea::Shutdown() {
   DCHECK(!is_shutdown_);
   is_shutdown_ = true;
   map_ = NULL;
   if (!backing_.get())
     return;
 
   bool success = task_runner_->PostShutdownBlockingTask(
       FROM_HERE,
       DomStorageTaskRunner::COMMIT_SEQUENCE,
       base::Bind(&DomStorageArea::ShutdownInCommitSequence, this));
   DCHECK(success);
 }
 
 void DomStorageArea::InitialImportIfNeeded() {
   if (is_initial_import_done_)
     return;
 
-  DCHECK_EQ(kLocalStorageNamespaceId, namespace_id_);
   DCHECK(backing_.get());
 
   ValuesMap initial_values;
   backing_->ReadAllValues(&initial_values);
   map_->SwapValues(&initial_values);
   is_initial_import_done_ = true;
 }
 
 DomStorageArea::CommitBatch* DomStorageArea::CreateCommitBatchIfNeeded() {
   DCHECK(!is_shutdown_);
   if (!commit_batch_.get()) {
     commit_batch_.reset(new CommitBatch());
 
     // Start a timer to commit any changes that accrue in the batch, but only if
     // no commits are currently in flight. In that case the timer will be
     // started after the commits have happened.
     if (!commit_batches_in_flight_) {
       task_runner_->PostDelayedTask(
           FROM_HERE,
           base::Bind(&DomStorageArea::OnCommitTimer, this),
           base::TimeDelta::FromSeconds(kCommitTimerSeconds));
     }
   }
   return commit_batch_.get();
 }
 
 void DomStorageArea::OnCommitTimer() {
-  DCHECK_EQ(kLocalStorageNamespaceId, namespace_id_);
   if (is_shutdown_)
     return;
 
   DCHECK(backing_.get());
-  DCHECK(commit_batch_.get());
-  DCHECK(!commit_batches_in_flight_);
+
+  // It's possible that there is nothing to commit, since a shallow copy occured
+  // before the timer fired.
+  if (!commit_batch_.get())
+    return;
 
   // This method executes on the primary sequence, we schedule
   // a task for immediate execution on the commit sequence.
   DCHECK(task_runner_->IsRunningOnPrimarySequence());
   bool success = task_runner_->PostShutdownBlockingTask(
       FROM_HERE,
       DomStorageTaskRunner::COMMIT_SEQUENCE,
       base::Bind(&DomStorageArea::CommitChanges, this,
                  base::Owned(commit_batch_.release())));
   ++commit_batches_in_flight_;
   DCHECK(success);
 }
 
 void DomStorageArea::CommitChanges(const CommitBatch* commit_batch) {
   // This method executes on the commit sequence.
   DCHECK(task_runner_->IsRunningOnCommitSequence());
   bool success = backing_->CommitChanges(commit_batch->clear_all_first,
                                          commit_batch->changed_values);
   DCHECK(success);  // TODO(michaeln): what if it fails?
   task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&DomStorageArea::OnCommitComplete, this));
 }
 
 void DomStorageArea::OnCommitComplete() {
   // We're back on the primary sequence in this method.
   DCHECK(task_runner_->IsRunningOnPrimarySequence());
+  --commit_batches_in_flight_;
   if (is_shutdown_)
     return;
-  --commit_batches_in_flight_;
   if (commit_batch_.get() && !commit_batches_in_flight_) {
     // More changes have accrued, restart the timer.
     task_runner_->PostDelayedTask(
         FROM_HERE,
         base::Bind(&DomStorageArea::OnCommitTimer, this),
         base::TimeDelta::FromSeconds(kCommitTimerSeconds));
   }
 }
 
 void DomStorageArea::ShutdownInCommitSequence() {
   // This method executes on the commit sequence.
   DCHECK(task_runner_->IsRunningOnCommitSequence());
   DCHECK(backing_.get());
   if (commit_batch_.get()) {
     // Commit any changes that accrued prior to the timer firing.
     bool success = backing_->CommitChanges(
         commit_batch_->clear_all_first,
         commit_batch_->changed_values);
     DCHECK(success);
   }
   commit_batch_.reset();
   backing_.reset();
+  session_storage_backing_ = NULL;
 }
 
 }  // namespace dom_storage