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

BUG=178980
TEST=manual (verified the memory stops increasing at a certain level)

Review URL: https://chromiumcodereview.appspot.com/12398008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@193585 0039d316-1c4b-4281-b951-d872f2087c98

7 files changed, 52 insertions, 5 deletions

diff --git a/webkit/dom_storage/dom_storage_area.h b/webkit/dom_storage/dom_storage_area.h
index 0c0a76b..57c0e89 100644
--- a/webkit/dom_storage/dom_storage_area.h
+++ b/webkit/dom_storage/dom_storage_area.h
@@ -80,6 +80,9 @@ class WEBKIT_STORAGE_EXPORT DomStorageArea
   // no longer do anything.
   void Shutdown();
 
+  // Returns true if the data is loaded in memory.
+  bool IsLoadedInMemory() const { return is_initial_import_done_; }
+
  private:
   friend class DomStorageAreaTest;
   FRIEND_TEST_ALL_PREFIXES(DomStorageAreaTest, DomStorageAreaBasics);
diff --git a/webkit/dom_storage/dom_storage_context.cc b/webkit/dom_storage/dom_storage_context.cc
index 8065ec6..80df009 100644
--- a/webkit/dom_storage/dom_storage_context.cc
+++ b/webkit/dom_storage/dom_storage_context.cc
@@ -167,7 +167,7 @@ void DomStorageContext::PurgeMemory() {
   StorageNamespaceMap::iterator found =
       namespaces_.find(kLocalStorageNamespaceId);
   if (found != namespaces_.end())
-    found->second->PurgeMemory();
+    found->second->PurgeMemory(DomStorageNamespace::PURGE_AGGRESSIVE);
 }
 
 void DomStorageContext::Shutdown() {
diff --git a/webkit/dom_storage/dom_storage_host.cc b/webkit/dom_storage/dom_storage_host.cc
index a8637e0..7f4fca1 100644
--- a/webkit/dom_storage/dom_storage_host.cc
+++ b/webkit/dom_storage/dom_storage_host.cc
@@ -61,6 +61,15 @@ bool DomStorageHost::ExtractAreaValues(
     // for sending a bad message.
     return true;
   }
+  if (!area->IsLoadedInMemory()) {
+    DomStorageNamespace* ns = GetNamespace(connection_id);
+    DCHECK(ns);
+    if (ns->CountInMemoryAreas() > kMaxInMemoryAreas) {
+      ns->PurgeMemory(DomStorageNamespace::PURGE_UNOPENED);
+      if (ns->CountInMemoryAreas() > kMaxInMemoryAreas)
+        ns->PurgeMemory(DomStorageNamespace::PURGE_AGGRESSIVE);
+    }
+  }
   area->ExtractValues(map);
   return true;
 }
@@ -146,6 +155,13 @@ DomStorageArea* DomStorageHost::GetOpenArea(int connection_id) {
   return found->second.area_;
 }
 
+DomStorageNamespace* DomStorageHost::GetNamespace(int connection_id) {
+  AreaMap::iterator found = connections_.find(connection_id);
+  if (found == connections_.end())
+    return NULL;
+  return found->second.namespace_;
+}
+
 // NamespaceAndArea
 
 DomStorageHost::NamespaceAndArea::NamespaceAndArea() {}
diff --git a/webkit/dom_storage/dom_storage_host.h b/webkit/dom_storage/dom_storage_host.h
index ccdfab3..7dc6321 100644
--- a/webkit/dom_storage/dom_storage_host.h
+++ b/webkit/dom_storage/dom_storage_host.h
@@ -60,6 +60,7 @@ class WEBKIT_STORAGE_EXPORT DomStorageHost {
   typedef std::map<int, NamespaceAndArea > AreaMap;
 
   DomStorageArea* GetOpenArea(int connection_id);
+  DomStorageNamespace* GetNamespace(int connection_id);
 
   scoped_refptr<DomStorageContext> context_;
   AreaMap connections_;
diff --git a/webkit/dom_storage/dom_storage_namespace.cc b/webkit/dom_storage/dom_storage_namespace.cc
index 4c1cbd7..941a169 100644
--- a/webkit/dom_storage/dom_storage_namespace.cc
+++ b/webkit/dom_storage/dom_storage_namespace.cc
@@ -117,7 +117,7 @@ void DomStorageNamespace::DeleteSessionStorageOrigin(const GURL& origin) {
   CloseStorageArea(area);
 }
 
-void DomStorageNamespace::PurgeMemory() {
+void DomStorageNamespace::PurgeMemory(PurgeOption option) {
   if (directory_.empty())
     return;  // We can't purge w/o backing on disk.
   AreaMap::iterator it = areas_.begin();
@@ -136,8 +136,12 @@ void DomStorageNamespace::PurgeMemory() {
       continue;
     }
 
-    // Otherwise, we can clear caches and such.
-    it->second.area_->PurgeMemory();
+    if (option == PURGE_AGGRESSIVE) {
+      // If aggressive is true, we clear caches and such
+      // for opened areas.
+      it->second.area_->PurgeMemory();
+    }
+
     ++it;
   }
 }
@@ -148,6 +152,14 @@ void DomStorageNamespace::Shutdown() {
     it->second.area_->Shutdown();
 }
 
+unsigned int DomStorageNamespace::CountInMemoryAreas() const {
+  unsigned int area_count = 0;
+  for (AreaMap::const_iterator it = areas_.begin(); it != areas_.end(); ++it) {
+    if (it->second.area_->IsLoadedInMemory())
+      ++area_count;
+  }
+  return area_count;
+}
 
 DomStorageNamespace::AreaHolder*
 DomStorageNamespace::GetAreaHolder(const GURL& origin) {
diff --git a/webkit/dom_storage/dom_storage_namespace.h b/webkit/dom_storage/dom_storage_namespace.h
index 78ef4d7..1d20e86 100644
--- a/webkit/dom_storage/dom_storage_namespace.h
+++ b/webkit/dom_storage/dom_storage_namespace.h
@@ -25,6 +25,16 @@ class SessionStorageDatabase;
 class WEBKIT_STORAGE_EXPORT DomStorageNamespace
     : public base::RefCountedThreadSafe<DomStorageNamespace> {
  public:
+  // Option for PurgeMemory.
+  enum PurgeOption {
+    // Purge unopened areas only.
+    PURGE_UNOPENED,
+
+    // Purge aggressively, i.e. discard cache even for areas that have
+    // non-zero open count.
+    PURGE_AGGRESSIVE,
+  };
+
   // Constructor for a LocalStorage namespace with id of 0
   // and an optional backing directory on disk.
   DomStorageNamespace(const base::FilePath& directory,  // may be empty
@@ -59,9 +69,11 @@ class WEBKIT_STORAGE_EXPORT DomStorageNamespace
 
   void DeleteLocalStorageOrigin(const GURL& origin);
   void DeleteSessionStorageOrigin(const GURL& origin);
-  void PurgeMemory();
+  void PurgeMemory(PurgeOption purge);
   void Shutdown();
 
+  unsigned int CountInMemoryAreas() const;
+
  private:
   friend class base::RefCountedThreadSafe<DomStorageNamespace>;
 
diff --git a/webkit/dom_storage/dom_storage_types.h b/webkit/dom_storage/dom_storage_types.h
index 1f663b4..e0a8509 100644
--- a/webkit/dom_storage/dom_storage_types.h
+++ b/webkit/dom_storage/dom_storage_types.h
@@ -32,6 +32,9 @@ const int64 kLocalStorageNamespaceId = 0;
 
 const int64 kInvalidSessionStorageNamespaceId = kLocalStorageNamespaceId;
 
+// Start purging memory if the number of in-memory areas exceeds this.
+const int64 kMaxInMemoryAreas = 100;
+
 // Value to indicate an area that not be opened.
 const int kInvalidAreaId = -1;