[Blob] BlobReader class & tests, and removal of all redundant reading.

content/browser/loader/upload_data_stream_builder.cc

Index: content/browser/loader/upload_data_stream_builder.cc
diff --git a/content/browser/loader/upload_data_stream_builder.cc b/content/browser/loader/upload_data_stream_builder.cc
index cab3a104572e3811b5c85d948c299b94b5bf33fb..ad276d7555828de6e04dc2124a813cd9995b92f6 100644
--- a/content/browser/loader/upload_data_stream_builder.cc
+++ b/content/browser/loader/upload_data_stream_builder.cc
@@ -4,6 +4,7 @@
 
 #include "content/browser/loader/upload_data_stream_builder.h"
 
+#include <limits>
 #include <utility>
 #include <vector>
 
@@ -13,11 +14,11 @@
 #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_disk_cache_entry_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_reader.h"
 #include "storage/browser/blob/blob_storage_context.h"
+#include "storage/browser/blob/upload_blob_element_reader.h"
 
 namespace disk_cache {
 class Entry;
@@ -69,89 +70,15 @@ class FileElementReader : public net::UploadFileElementReader {
   DISALLOW_COPY_AND_ASSIGN(FileElementReader);
 };
 
-// This owns the provided ResourceRequestBody. This is necessary to ensure the
-// BlobData and open disk cache entries survive until upload completion.
-class DiskCacheElementReader : public net::UploadDiskCacheEntryElementReader {
- public:
-  DiskCacheElementReader(ResourceRequestBody* resource_request_body,
-                         disk_cache::Entry* disk_cache_entry,
-                         int disk_cache_stream_index,
-                         const ResourceRequestBody::Element& element)
-      : net::UploadDiskCacheEntryElementReader(disk_cache_entry,
-                                               disk_cache_stream_index,
-                                               element.offset(),
-                                               element.length()),
-        resource_request_body_(resource_request_body) {
-    DCHECK_EQ(ResourceRequestBody::Element::TYPE_DISK_CACHE_ENTRY,
-              element.type());
-  }
-
-  ~DiskCacheElementReader() override {}
-
- private:
-  scoped_refptr<ResourceRequestBody> resource_request_body_;
-
-  DISALLOW_COPY_AND_ASSIGN(DiskCacheElementReader);
-};
-
-void ResolveBlobReference(
-    ResourceRequestBody* body,
-    storage::BlobStorageContext* blob_context,
-    const ResourceRequestBody::Element& element,
-    std::vector<std::pair<const ResourceRequestBody::Element*,
-                          const storage::BlobDataItem*>>* 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 (snapshot->items().empty())
-    return;
-
-  // Append the elements in the referenced blob data.
-  for (const auto& item : snapshot->items()) {
-    DCHECK_NE(storage::DataElement::TYPE_BLOB, item->type());
-    resolved_elements->push_back(
-        std::make_pair(item->data_element_ptr(), item.get()));
-  }
-  const void* key = snapshot.get();
-  body->SetUserData(key, snapshot.release());
-}
-
 }  // namespace
 
 scoped_ptr<net::UploadDataStream> UploadDataStreamBuilder::Build(
     ResourceRequestBody* body,
     storage::BlobStorageContext* blob_context,
     storage::FileSystemContext* file_system_context,
-    base::TaskRunner* file_task_runner) {
-  // Resolve all blob elements.
-  std::vector<std::pair<const ResourceRequestBody::Element*,
-                        const storage::BlobDataItem*>> 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(body, blob_context, element, &resolved_elements);
-    } else if (element.type() !=
-               ResourceRequestBody::Element::TYPE_DISK_CACHE_ENTRY) {
-      resolved_elements.push_back(std::make_pair(&element, nullptr));
-    } else {
-      NOTREACHED();
-    }
-  }
-
+    base::SingleThreadTaskRunner* file_task_runner) {
   ScopedVector<net::UploadElementReader> element_readers;
-  for (const auto& element_and_blob_item_pair : resolved_elements) {
-    const ResourceRequestBody::Element& element =
-        *element_and_blob_item_pair.first;
+  for (const auto& element : *body->elements()) {
     switch (element.type()) {
       case ResourceRequestBody::Element::TYPE_BYTES:
         element_readers.push_back(new BytesElementReader(body, element));
@@ -172,22 +99,20 @@ scoped_ptr<net::UploadDataStream> UploadDataStreamBuilder::Build(
                 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_DISK_CACHE_ENTRY: {
-        // TODO(gavinp): If Build() is called with a DataElement of
-        // TYPE_DISK_CACHE_ENTRY then this code won't work because we won't call
-        // ResolveBlobReference() and so we won't find |item|. Is this OK?
-        const storage::BlobDataItem* item = element_and_blob_item_pair.second;
-        element_readers.push_back(
-            new DiskCacheElementReader(body, item->disk_cache_entry(),
-                                       item->disk_cache_stream_index(),
-                                       element));
+      case ResourceRequestBody::Element::TYPE_BLOB: {
+        // Modify the UploadBlobElementReader if offsets and length are
+        // needed.

[michaeln, 2015/09/28 21:52:07]

The comment is a little confusing. It's describing what would have to happen to
specify a subset of the blob using .length and .offset. It'd be clearer to state
that specifying a subset is not supported, only whole blobs. But really, the
DECHECKs say that even better than a comment... I think you could delete the
comment.

[dmurph, 2015/09/29 21:29:21]

Done.

+        DCHECK_EQ(std::numeric_limits<uint64_t>::max(), element.length());
+        DCHECK_EQ(0ul, element.offset());
+        scoped_ptr<storage::BlobDataHandle> handle =
+            blob_context->GetBlobDataFromUUID(element.blob_uuid());
+        storage::BlobDataHandle* handle_ptr = handle.get();
+        element_readers.push_back(new storage::UploadBlobElementReader(
+            handle_ptr->CreateReader(file_system_context, file_task_runner),
+            handle.Pass()));
         break;
       }
+      case ResourceRequestBody::Element::TYPE_DISK_CACHE_ENTRY:
       case ResourceRequestBody::Element::TYPE_UNKNOWN:
         NOTREACHED();
         break;