[Storage] Blob Storage Refactoring pt 1

content/browser/loader/upload_data_stream_builder.cc

 // Copyright 2013 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 "content/browser/loader/upload_data_stream_builder.h"
 
 #include "base/logging.h"
 #include "content/browser/fileapi/upload_file_system_file_element_reader.h"
 #include "content/common/resource_request_body.h"
 #include "net/base/elements_upload_data_stream.h"
 #include "net/base/upload_bytes_element_reader.h"
 #include "net/base/upload_file_element_reader.h"
 #include "storage/browser/blob/blob_data_handle.h"
+#include "storage/browser/blob/blob_data_snapshot.h"
 #include "storage/browser/blob/blob_storage_context.h"
 
-using storage::BlobData;
-using storage::BlobDataHandle;
-using storage::BlobStorageContext;
-
 namespace content {
 namespace {
 
 // A subclass of net::UploadBytesElementReader which owns ResourceRequestBody.
 class BytesElementReader : public net::UploadBytesElementReader {
  public:
   BytesElementReader(ResourceRequestBody* resource_request_body,
                      const ResourceRequestBody::Element& element)
       : net::UploadBytesElementReader(element.bytes(), element.length()),
         resource_request_body_(resource_request_body) {
@@ skipping 27 matching lines @@
 
   ~FileElementReader() override {}
 
  private:
   scoped_refptr<ResourceRequestBody> resource_request_body_;
 
   DISALLOW_COPY_AND_ASSIGN(FileElementReader);
 };
 
 void ResolveBlobReference(
+    ResourceRequestBody* body,
     storage::BlobStorageContext* blob_context,
     const ResourceRequestBody::Element& element,
     std::vector<const ResourceRequestBody::Element*>* resolved_elements) {
   DCHECK(blob_context);
   scoped_ptr<storage::BlobDataHandle> handle =
       blob_context->GetBlobDataFromUUID(element.blob_uuid());
   DCHECK(handle);
   if (!handle)
     return;
 
+  // TODO(dmurph): Create a reader for blobs instead of decomposing the blob
+  // and storing the snapshot on the request to keep the resources around.
+  // Currently a handle is attached to the request in the resource dispatcher
+  // host, so we know the blob won't go away, but it's not very clear or useful.
+  scoped_ptr<storage::BlobDataSnapshot> snapshot = handle->CreateSnapshot();
   // If there is no element in the referred blob data, just return.
-  if (handle->data()->items().empty())
+  if (snapshot->items().empty())
     return;
 
   // Append the elements in the referenced blob data.
-  for (size_t i = 0; i < handle->data()->items().size(); ++i) {
-    const BlobData::Item& item = handle->data()->items().at(i);
-    DCHECK_NE(BlobData::Item::TYPE_BLOB, item.type());
-    resolved_elements->push_back(&item);
+  for (const auto& item : snapshot->items()) {
+    DCHECK_NE(storage::DataElement::TYPE_BLOB, item->type());
+    resolved_elements->push_back(item->data_element_ptr());
   }
+  body->SetUserData(snapshot.get(), snapshot.release());

[michaeln, 2015/01/22 02:18:09]

i'm don't think this is safe, release() can get called prior to get, elsewhere
this is done as 

    const void* key = bar.get();
    foo->SetUserData(key, bar.release());

[dmurph, 2015/01/23 00:10:18]

Done.

 }
 
 }  // namespace
 
 scoped_ptr<net::UploadDataStream> UploadDataStreamBuilder::Build(
     ResourceRequestBody* body,
-    BlobStorageContext* blob_context,
+    storage::BlobStorageContext* blob_context,
     storage::FileSystemContext* file_system_context,
     base::TaskRunner* file_task_runner) {
   // Resolve all blob elements.
   std::vector<const ResourceRequestBody::Element*> resolved_elements;
   for (size_t i = 0; i < body->elements()->size(); ++i) {
     const ResourceRequestBody::Element& element = (*body->elements())[i];
     if (element.type() == ResourceRequestBody::Element::TYPE_BLOB)
-      ResolveBlobReference(blob_context, element, &resolved_elements);
+      ResolveBlobReference(body, blob_context, element, &resolved_elements);
     else
       resolved_elements.push_back(&element);
   }
 
   ScopedVector<net::UploadElementReader> element_readers;
   for (size_t i = 0; i < resolved_elements.size(); ++i) {
     const ResourceRequestBody::Element& element = *resolved_elements[i];
     switch (element.type()) {
       case ResourceRequestBody::Element::TYPE_BYTES:
         element_readers.push_back(new BytesElementReader(body, element));
         break;
       case ResourceRequestBody::Element::TYPE_FILE:
         element_readers.push_back(
             new FileElementReader(body, file_task_runner, element));
         break;
       case ResourceRequestBody::Element::TYPE_FILE_FILESYSTEM:
         // If |body| contains any filesystem URLs, the caller should have
         // supplied a FileSystemContext.
         DCHECK(file_system_context);
         element_readers.push_back(
             new content::UploadFileSystemFileElementReader(
                 file_system_context,
                 element.filesystem_url(),
                 element.offset(),
                 element.length(),
                 element.expected_modification_time()));
         break;
       case ResourceRequestBody::Element::TYPE_BLOB:
         // Blob elements should be resolved beforehand.
+        // TODO(dmurph): Create blob reader and store the snapshot in there.
         NOTREACHED();
         break;
       case ResourceRequestBody::Element::TYPE_UNKNOWN:
         NOTREACHED();
         break;
     }
   }
 
   return make_scoped_ptr(
       new net::ElementsUploadDataStream(element_readers.Pass(),
                                         body->identifier()));
 }
 
 }  // namespace content