Break large blobs into multiple ipcs during creation.

content/common/webblobregistry_impl.cc

Index: content/common/webblobregistry_impl.cc
===================================================================
--- content/common/webblobregistry_impl.cc	(revision 102191)
+++ content/common/webblobregistry_impl.cc	(working copy)
@@ -10,6 +10,7 @@
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebString.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebURL.h"
 #include "webkit/blob/blob_data.h"
+#include "webkit/glue/webkit_glue.h"
 
 using WebKit::WebBlobData;
 using WebKit::WebString;
@@ -24,9 +25,50 @@
 
 void WebBlobRegistryImpl::registerBlobURL(
     const WebURL& url, WebBlobData& data) {
-  scoped_refptr<webkit_blob::BlobData> blob_data(
-      new webkit_blob::BlobData(data));
-  sender_->Send(new BlobHostMsg_RegisterBlobUrl(url, blob_data));
+  sender_->Send(new BlobHostMsg_RegisterUnfinalizedBlobUrl(url));
+  size_t i = 0;
+  WebBlobData::Item data_item;
+  while (data.itemAt(i++, data_item)) {
+    webkit_blob::BlobData::Item item;
+    switch (data_item.type) {
+      case WebBlobData::Item::TypeData: {
+        // WebBlobData does not allow partial data.
+        DCHECK(!data_item.offset && data_item.length == -1);
+        const size_t kMaxDataChunkSize = 5 * 1024 * 1024;

[jianli, 2011/09/23 23:00:42]

Why do we need to enforce this size constraint?

If we do this, I think it would be better to abort the request rather than
truncating the data silently.

[michaeln, 2011/09/24 01:15:24]

It's not truncated? There are a series of BlobHostMsg_AppendBlobDataItem
messages which send all of the data. See the while() loop.

IPC messages have a 'max' size constraint, we need to fit underneath that size
constraint. 5M is well beneath that limit, it could be larger. Kind of arbitrary
what value to use here (so long as it's under the max). I choose 5M so the size
of contiguous heap allocated blocks don't have to be too large.

[jianli, 2011/09/27 01:12:18]

Got it. Could you please add comment for this so that other people without the
background can understand this logic easily?

[michaeln, 2011/09/27 23:27:31]

Done.

+        size_t data_size = data_item.data.size();
+        const char* data_ptr = data_item.data.data();
+        while (data_size) {
+          size_t chunk_size = std::min(data_size, kMaxDataChunkSize);
+          item.SetToData(data_ptr, chunk_size);
+          data_size -= chunk_size;
+          data_ptr += chunk_size;
+          sender_->Send(new BlobHostMsg_AppendBlobDataItem(url, item));
+        }
+        break;
+      }
+      case WebBlobData::Item::TypeFile:
+        item.SetToFile(
+            webkit_glue::WebStringToFilePath(data_item.filePath),
+            static_cast<uint64>(data_item.offset),
+            static_cast<uint64>(data_item.length),
+            base::Time::FromDoubleT(data_item.expectedModificationTime));
+        sender_->Send(new BlobHostMsg_AppendBlobDataItem(url, item));
+        break;
+      case WebBlobData::Item::TypeBlob:
+        if (data_item.length) {
+          item.SetToBlob(
+              data_item.blobURL,
+              static_cast<uint64>(data_item.offset),
+              static_cast<uint64>(data_item.length));
+        }
+        sender_->Send(new BlobHostMsg_AppendBlobDataItem(url, item));
+        break;
+      default:
+        NOTREACHED();
+    }
+  }
+  sender_->Send(new BlobHostMsg_FinalizeBlob(
+      url, data.contentType().utf8().data()));
 }
 
 void WebBlobRegistryImpl::registerBlobURL(