Optimized webstorage performance

content/renderer/renderer_webstoragearea_impl.cc

Index: content/renderer/renderer_webstoragearea_impl.cc
diff --git a/content/renderer/renderer_webstoragearea_impl.cc b/content/renderer/renderer_webstoragearea_impl.cc
index a7cbfb695653da41a2fcdcf5a5c070848a88c2d3..c065b8b0c67e824b294c9f170d1423f0cea858c3 100644
--- a/content/renderer/renderer_webstoragearea_impl.cc
+++ b/content/renderer/renderer_webstoragearea_impl.cc
@@ -11,6 +11,7 @@
 #include "content/common/dom_storage_messages.h"
 #include "content/renderer/render_thread_impl.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebURL.h"
+#include "third_party/WebKit/Source/Platform/chromium/public/WebCommon.h"
 #include "webkit/dom_storage/dom_storage_types.h"
 
 using WebKit::WebString;
@@ -75,21 +76,75 @@ WebString RendererWebStorageAreaImpl::key(unsigned index) {
 
 WebString RendererWebStorageAreaImpl::getItem(const WebString& key) {
   NullableString16 value;
-  RenderThreadImpl::current()->Send(
-      new DOMStorageHostMsg_GetItem(connection_id_, key, &value));
+  unsigned value_len;
+  base::SharedMemoryHandle browser_handle = base::SharedMemory::NULLHandle();
+  dom_storage::IPC_Flag ipc_flag;
+  RenderThreadImpl::current()->Send(new DOMStorageHostMsg_GetItem(
+                                    connection_id_, key,
+                                    reinterpret_cast<int*>(&ipc_flag),
+                                    &browser_handle, &value_len, &value));
+  if (ipc_flag == dom_storage::SharedMemory) {
+    base::SharedMemory shared_buf(browser_handle, true);
+    shared_buf.Map(value_len*sizeof(char16));
+    string16 shm_str;
+    shared_buf.Lock();
+    shm_str.append(static_cast<char16*>(shared_buf.memory()), value_len);
+    shared_buf.Unlock();
+    shared_buf.Close();
+    value = NullableString16(shm_str, false);
+  }
   return value;
 }
 
 void RendererWebStorageAreaImpl::setItem(
     const WebString& key, const WebString& value, const WebURL& url,
     WebStorageArea::Result& result, WebString& old_value_webkit) {
-  if (key.length() + value.length() > dom_storage::kPerAreaQuota) {
+  size_t value_len = value.length()*sizeof(WebKit::WebUChar);
+  base::SharedMemoryHandle shared_mem_handle;
+  if (key.length() + value_len > dom_storage::kPerAreaQuota) {
     result = ResultBlockedByQuota;
     return;
   }
   NullableString16 old_value;
-  RenderThreadImpl::current()->Send(new DOMStorageHostMsg_SetItem(
-      connection_id_, key, value, url, &result, &old_value));
+
+  if (value_len < dom_storage::kShmEnableThreshold) {
+    RenderThreadImpl::current()->Send(new DOMStorageHostMsg_SetItem(
+        connection_id_, key, value, url, &result, &old_value));
+    old_value_webkit = old_value;
+    return;
+  }
+  // Try Allocate a shared memory buffer to hold the bulk of data.
+  // if fail, go through channel
+#if defined(OS_WIN)
+  base::SharedMemory shared_buf;
+  if (!shared_buf.CreateAndMapAnonymous(value_len)) {
+    RenderThreadImpl::current()->Send(new DOMStorageHostMsg_SetItem(
+        connection_id_, key, value, url, &result, &old_value));
+    old_value_webkit = old_value;
+    return;
+  }
+#elif defined(OS_POSIX)
+  shared_mem_handle =
+      content::RenderThread::Get()->HostAllocateSharedMemoryBuffer(value_len);
+  if (!base::SharedMemory::IsHandleValid(shared_mem_handle)) {
+    RenderThreadImpl::current()->Send(new DOMStorageHostMsg_SetItem(
+        connection_id_, key, value, url, &result, &old_value));
+    old_value_webkit = old_value;
+    return;
+  }
+  base::SharedMemory shared_buf(shared_mem_handle, false);
+  shared_buf.Map(value_len);
+#endif
+  // Go through shm, Copy the bits into shared memory.
+  shared_buf.Lock();
+  memcpy(shared_buf.memory(), value.data(), value_len);
+  shared_buf.Unlock();
+  // give to process
+  shared_mem_handle = shared_buf.handle();
+  RenderThreadImpl::current()->Send(new DOMStorageHostMsg_SetItemOpt(
+      connection_id_, key, value.length(), shared_mem_handle, url,
+      &result, &old_value));
+  shared_buf.Close();
   old_value_webkit = old_value;
 }