Purge in-memory localStorage areas if the # of areas exceeds the limit

webkit/dom_storage/dom_storage_cached_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_cached_area.h"
 
 #include "base/basictypes.h"
 #include "base/time.h"
 #include "base/metrics/histogram.h"
 #include "webkit/dom_storage/dom_storage_map.h"
 #include "webkit/dom_storage/dom_storage_proxy.h"
 
 namespace dom_storage {
 
 DomStorageCachedArea::DomStorageCachedArea(
-    int64 namespace_id, const GURL& origin, DomStorageProxy* proxy)
+    int64 namespace_id, const GURL& origin, DomStorageProxy* proxy,
+    int64 storage_size)
     : ignore_all_mutations_(false),
       namespace_id_(namespace_id), origin_(origin),
-      proxy_(proxy), weak_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
+      proxy_(proxy), weak_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)),
+      global_storage_size_(storage_size) {
 }
 
 DomStorageCachedArea::~DomStorageCachedArea() {
 }
 
 unsigned DomStorageCachedArea::GetLength(int connection_id) {
   PrimeIfNeeded(connection_id);
   return map_->Length();
 }
 
@@ skipping 10 matching lines @@
 }
 
 bool DomStorageCachedArea::SetItem(
     int connection_id, const string16& key,
     const string16& value, const GURL& page_url) {
   // A quick check to reject obviously overbudget items to avoid
   // the priming the cache.
   if (key.length() + value.length() > dom_storage::kPerAreaQuota)
     return false;
 
+  // TENTATIVE: Limit the global data to 512MB.
+  if (key.length() + value.length() + global_storage_size_
+      > 512 * 1024 * 1024) {
+    return false;
+  }
+
   PrimeIfNeeded(connection_id);
   NullableString16 unused;
   if (!map_->SetItem(key, value, &unused))
     return false;
 
   // Ignore mutations to 'key' until OnSetItemComplete.
   ignore_key_mutations_[key]++;
   proxy_->SetItem(
       connection_id, key, value, page_url,
       base::Bind(&DomStorageCachedArea::OnSetItemComplete,
@@ skipping 158 matching lines @@
     ignore_key_mutations_.erase(found);
 }
 
 void DomStorageCachedArea::OnClearComplete(bool success) {
   DCHECK(success);
   DCHECK(ignore_all_mutations_);
   ignore_all_mutations_ = false;
 }
 
 }  // namespace dom_storage