[Storage] Consoliation of BlobItems with small size

content/child/webblobregistry_impl.cc

Index: content/child/webblobregistry_impl.cc
diff --git a/content/child/webblobregistry_impl.cc b/content/child/webblobregistry_impl.cc
index d673c2a657fddc9eb044eda48b4762719e8fb607..b613baff5b4dda03a6c1a530b211cef47d48250e 100644
--- a/content/child/webblobregistry_impl.cc
+++ b/content/child/webblobregistry_impl.cc
@@ -43,15 +43,27 @@ void WebBlobRegistryImpl::registerBlobData(
     const blink::WebString& uuid, const blink::WebBlobData& data) {
   const std::string uuid_str(uuid.utf8());
 
+  std::vector<char> consolidating_buffer;
+  consolidating_buffer.reserve(kLargeThresholdBytes);

[michaeln, 2015/01/22 00:46:42]

should we care about preallocating this much mem? if so, maybe this large
reservation can be done inside of BufferBlobData if data.len > buf.capacity? do
you know what the default capacity typically is?

[dmurph, 2015/01/22 19:54:17]

I can just use the internal vector in DataElement.  The resizing behavior is
pretty smart std::vector, so I don't think we have to worry about crazy append
allocation.

+
   sender_->Send(new BlobHostMsg_StartBuilding(uuid_str));
   size_t i = 0;
   WebBlobData::Item data_item;
   while (data.itemAt(i++, data_item)) {
+    if (data_item.length == 0) {
+      continue;
+    }
+    if (data_item.type != WebBlobData::Item::TypeData &&
+        consolidating_buffer.size() != 0) {
+      FlushBlobItemBuffer(uuid_str, &consolidating_buffer);
+    }
     switch (data_item.type) {
       case WebBlobData::Item::TypeData: {
         // WebBlobData does not allow partial data items.
         DCHECK(!data_item.offset && data_item.length == -1);
-        SendDataForBlob(uuid_str, data_item.data);
+        DCHECK_EQ(data_item.length,
+                  static_cast<long long>(data_item.data.size()));
+        BufferBlobData(uuid_str, data_item.data, &consolidating_buffer);
         break;
       }
       case WebBlobData::Item::TypeFile:
@@ -95,6 +107,9 @@ void WebBlobRegistryImpl::registerBlobData(
         NOTREACHED();
     }
   }
+  if (consolidating_buffer.size() != 0) {
+    FlushBlobItemBuffer(uuid_str, &consolidating_buffer);
+  }
   sender_->Send(new BlobHostMsg_FinishBuilding(
       uuid_str, data.contentType().utf8().data()));
 }
@@ -116,37 +131,59 @@ void WebBlobRegistryImpl::revokePublicBlobURL(const WebURL& url) {
   sender_->Send(new BlobHostMsg_RevokePublicURL(url));
 }
 
-void WebBlobRegistryImpl::SendDataForBlob(const std::string& uuid_str,
-                                          const WebThreadSafeData& data) {
+void WebBlobRegistryImpl::FlushBlobItemBuffer(
+    const std::string& uuid_str,
+    std::vector<char>* consolidating_buffer) const {
+  DCHECK_NE(consolidating_buffer->size(), 0ul);
+  DCHECK_LT(consolidating_buffer->size(), kLargeThresholdBytes);
+  storage::BlobData::Item item;
+  item.SetToBytes(&(*consolidating_buffer)[0], consolidating_buffer->size());
+  sender_->Send(new BlobHostMsg_AppendBlobDataItem(uuid_str, item));
+  consolidating_buffer->clear();
+}
 
-  if (data.size() == 0)
-    return;
-  if (data.size() < kLargeThresholdBytes) {
-    storage::BlobData::Item item;
-    item.SetToBytes(data.data(), data.size());
-    sender_->Send(new BlobHostMsg_AppendBlobDataItem(uuid_str, item));
+void WebBlobRegistryImpl::BufferBlobData(
+    const std::string& uuid_str,
+    const blink::WebThreadSafeData& data,
+    std::vector<char>* consolidating_buffer) {
+  size_t buffer_size = consolidating_buffer->size();
+  size_t data_size = data.size();
+  DCHECK_NE(data_size, 0ul);
+  if (buffer_size != 0 && buffer_size + data_size >= kLargeThresholdBytes) {
+    FlushBlobItemBuffer(uuid_str, consolidating_buffer);
+    buffer_size = 0;
+  }
+  if (data_size >= kLargeThresholdBytes) {
+    SendOversizedDataForBlob(uuid_str, data);
   } else {
-    // We handle larger amounts of data via SharedMemory instead of
-    // writing it directly to the IPC channel.
-    size_t shared_memory_size = std::min(
-        data.size(), kMaxSharedMemoryBytes);
-    scoped_ptr<base::SharedMemory> shared_memory(
-        ChildThread::AllocateSharedMemory(shared_memory_size,
-                                          sender_.get()));
-    CHECK(shared_memory.get());
-    if (!shared_memory->Map(shared_memory_size))
-      CHECK(false);
+    DCHECK_LT(buffer_size + data_size, kLargeThresholdBytes);
+    consolidating_buffer->insert(consolidating_buffer->end(), data.data(),
+                                 data.data() + data_size);
+  }
+}
 
-    size_t data_size = data.size();
-    const char* data_ptr = data.data();
-    while (data_size) {
-      size_t chunk_size = std::min(data_size, shared_memory_size);
-      memcpy(shared_memory->memory(), data_ptr, chunk_size);
-      sender_->Send(new BlobHostMsg_SyncAppendSharedMemory(
-          uuid_str, shared_memory->handle(), chunk_size));
-      data_size -= chunk_size;
-      data_ptr += chunk_size;
-    }
+void WebBlobRegistryImpl::SendOversizedDataForBlob(
+    const std::string& uuid_str,
+    const blink::WebThreadSafeData& data) {
+  DCHECK_GE(data.size(), kLargeThresholdBytes);
+  // We handle larger amounts of data via SharedMemory instead of
+  // writing it directly to the IPC channel.
+  size_t shared_memory_size = std::min(data.size(), kMaxSharedMemoryBytes);
+  scoped_ptr<base::SharedMemory> shared_memory(
+      ChildThread::AllocateSharedMemory(shared_memory_size, sender_.get()));
+  CHECK(shared_memory.get());
+  if (!shared_memory->Map(shared_memory_size))
+    CHECK(false);
+
+  size_t data_size = data.size();
+  const char* data_ptr = data.data();
+  while (data_size) {
+    size_t chunk_size = std::min(data_size, shared_memory_size);
+    memcpy(shared_memory->memory(), data_ptr, chunk_size);
+    sender_->Send(new BlobHostMsg_SyncAppendSharedMemory(
+        uuid_str, shared_memory->handle(), chunk_size));
+    data_size -= chunk_size;
+    data_ptr += chunk_size;
   }
 }