[BlobAsync] Disk support for blob storage

storage/browser/blob/blob_flattener.cc

Index: storage/browser/blob/blob_flattener.cc
diff --git a/storage/browser/blob/blob_flattener.cc b/storage/browser/blob/blob_flattener.cc
new file mode 100644
index 0000000000000000000000000000000000000000..1242c5b7e7e125974191e56f8f9a76ebe35724dc
--- /dev/null
+++ b/storage/browser/blob/blob_flattener.cc
@@ -0,0 +1,127 @@
+// Copyright 2016 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 "storage/browser/blob/blob_flattener.h"
+
+#include <limits>
+#include <set>
+#include <utility>
+
+#include "storage/browser/blob/blob_async_transport_request_builder.h"
+#include "storage/browser/blob/blob_data_builder.h"
+#include "storage/browser/blob/blob_slice.h"
+#include "storage/browser/blob/blob_storage_context.h"
+#include "storage/browser/blob/blob_storage_registry.h"
+#include "storage/browser/blob/shareable_blob_data_item.h"
+#include "storage/common/data_element.h"
+
+namespace storage {
+namespace {
+using ItemCopyEntry = InternalBlobData::ItemCopyEntry;
+
+bool IsBytes(DataElement::Type type) {
+  return type == DataElement::TYPE_BYTES ||
+         type == DataElement::TYPE_BYTES_DESCRIPTION;
+}
+
+}  // namespace
+
+// static
+BlobFlattener::BlobFlattener(const BlobDataBuilder& input_builder,
+                             InternalBlobData* output_blob,
+                             BlobStorageRegistry* registry) {
+  const std::vector<scoped_refptr<BlobDataItem>>& transport_items =
+      input_builder.items_;
+  const std::string& uuid = input_builder.uuid_;
+
+  std::set<std::string> dependent_blob_uuids;
+  bool contains_pending_content = false;
+  for (scoped_refptr<BlobDataItem> transport_item : transport_items) {
+    DataElement::Type type = transport_item->type();
+    contains_pending_content |= type == DataElement::TYPE_BYTES_DESCRIPTION;
+
+    if (IsBytes(type)) {
+      DCHECK_NE(0 + DataElement::kUnknownSize, transport_item->length());
+      memory_needed += transport_item->length();
+      total_size += transport_item->length();
+      output_blob->AppendSharedBlobItem(
+          uuid, new ShareableBlobDataItem(std::move(transport_item)));
+      continue;
+    }
+    if (type == DataElement::TYPE_BLOB) {
+      InternalBlobData* ref_entry =
+          registry->GetEntry(transport_item->blob_uuid());
+
+      if (!ref_entry || transport_item->blob_uuid() == uuid) {
+        status = BlobStatus::ERR_INVALID_CONSTRUCTION_ARGUMENTS;
+        return;
+      }
+
+      if (BlobStatusIsError(ref_entry->status())) {
+        status = BlobStatus::ERR_REFERENCED_BLOB_BROKEN;
+        return;
+      }
+
+      if (dependent_blob_uuids.find(transport_item->blob_uuid()) ==
+          dependent_blob_uuids.end()) {
+        dependent_blobs.push_back(
+            std::make_pair(transport_item->blob_uuid(), ref_entry));
+        dependent_blob_uuids.insert(transport_item->blob_uuid());
+      }
+
+      uint64_t length = transport_item->length() == DataElement::kUnknownSize
+                            ? ref_entry->total_size()
+                            : transport_item->length();
+      total_size += length;
+
+      // If we're referencing the whole blob, then we don't need to slice.
+      if (transport_item->offset() == 0 && length == ref_entry->total_size()) {
+        for (const auto& shareable_item : ref_entry->items()) {
+          output_blob->AppendSharedBlobItem(uuid, shareable_item);
+        }
+        continue;
+      }
+
+      // Validate our reference has good offset & length.
+      if (transport_item->offset() + transport_item->length() >
+          ref_entry->total_size()) {
+        status = BlobStatus::ERR_INVALID_CONSTRUCTION_ARGUMENTS;
+        return;
+      }
+
+      BlobSlice slice(*ref_entry, transport_item->offset(),
+                      transport_item->length());
+
+      if (slice.first_source_item) {
+        copies.push_back(ItemCopyEntry(slice.first_source_item,
+                                       slice.first_item_slice_offset,
+                                       slice.dest_items.front()));
+      }
+      if (slice.last_source_item) {
+        copies.push_back(
+            ItemCopyEntry(slice.last_source_item, 0, slice.dest_items.back()));
+      }
+
+      memory_needed += slice.copying_memory_size;
+      for (auto& shareable_item : slice.dest_items) {
+        output_blob->AppendSharedBlobItem(uuid, std::move(shareable_item));
+      }
+      continue;
+    }
+    if (type == DataElement::TYPE_FILE) {
+      contains_pending_content |=
+          transport_item->path().value() ==
+          BlobDataBuilder::kAppendFutureFileTemporaryFileName;
+    }
+    total_size += transport_item->length();
+    output_blob->AppendSharedBlobItem(
+        uuid, new ShareableBlobDataItem(std::move(transport_item)));
+  }
+  status = contains_pending_content ? BlobStatus::PENDING_DATA_POPULATION
+                                    : BlobStatus::DONE;
+}
+
+BlobFlattener::~BlobFlattener() {}
+
+}  // namespace storage