[BlobAsync] Asynchronous Blob Construction Final Patch

storage/browser/blob/blob_async_transport_strategy.h

-// Copyright 2015 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.
-
-#ifndef STORAGE_BROWSER_BLOB_BLOB_ASYNC_TRANSPORT_STRATEGY_H_
-#define STORAGE_BROWSER_BLOB_BLOB_ASYNC_TRANSPORT_STRATEGY_H_
-
-#include <stddef.h>
-#include <stdint.h>
-
-#include <map>
-#include <vector>
-
-#include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
-#include "storage/browser/blob/blob_data_builder.h"
-#include "storage/browser/storage_browser_export.h"
-#include "storage/common/blob_storage/blob_item_bytes_request.h"
-#include "storage/common/data_element.h"
-
-namespace storage {
-
-// This class computes and stores the strategy for asynchronously transporting
-// memory from the renderer to the browser. We take memory constraints of our
-// system and the description of a blob, and figure out:
-// 1) How to store the blob data in the browser process: in memory or on disk.
-// 2) How to transport the data from the renderer: ipc payload, shared memory,
-//    or file handles.
-// We then generate data requests for that blob's memory and seed a
-// BlobDataBuilder for storing that data.
-//
-// Note: This class does not compute requests by using the 'shortcut' method,
-//       where the data is already present in the blob description, and will
-//       always give the caller the full strategy for requesting all data from
-//       the renderer.
-class STORAGE_EXPORT BlobAsyncTransportStrategy {
- public:
-  enum Error {
-    ERROR_NONE = 0,
-    ERROR_TOO_LARGE,  // This item can't fit in disk or memory
-    ERROR_INVALID_PARAMS
-  };
-
-  struct RendererMemoryItemRequest {
-    RendererMemoryItemRequest();
-    // This is the index of the item in the builder on the browser side.
-    size_t browser_item_index;
-    // Note: For files this offset should always be 0, as the file offset in
-    //       segmentation is handled by the handle_offset in the message.  This
-    //       offset is used for populating a chunk when the data comes back to
-    //       the browser.
-    size_t browser_item_offset;
-    BlobItemBytesRequest message;
-    bool received;
-  };
-
-  BlobAsyncTransportStrategy();
-  virtual ~BlobAsyncTransportStrategy();
-
-  // This call does the computation to create the requests and builder for the
-  // blob given the memory constraints and blob description. |memory_available|
-  // is the total amount of memory we can offer for storing blobs.
-  // This method can only be called once.
-  void Initialize(size_t max_ipc_memory_size,
-                  size_t max_shared_memory_size,
-                  size_t max_file_size,
-                  uint64_t disk_space_left,
-                  size_t memory_available,
-                  const std::string& uuid,
-                  const std::vector<DataElement>& blob_item_infos);
-
-  // The sizes of the handles being used (by handle index) in the async
-  // operation. This is used for both files or shared memory, as their use is
-  // mutually exclusive.
-  const std::vector<size_t>& handle_sizes() const { return handle_sizes_; }
-
-  // The requests for memory, segmented as described above, along with their
-  // destination browser indexes and offsets.
-  const std::vector<RendererMemoryItemRequest>& requests() const {
-    return requests_;
-  }
-
-  // Marks the request at the given request number as recieved.
-  void MarkRequestAsReceived(size_t request_num) {
-    DCHECK_LT(request_num, requests_.size());
-    requests_[request_num].received = true;
-  }
-
-  // A BlobDataBuilder which can be used to construct the Blob in the
-  // BlobStorageContext object after:
-  // * The bytes items from AppendFutureData are populated by
-  //   PopulateFutureData.
-  // * The temporary files from AppendFutureFile are populated by
-  //   PopulateFutureFile.
-  BlobDataBuilder* blob_builder() { return builder_.get(); }
-
-  // The total bytes size of memory items in the blob.
-  uint64_t total_bytes_size() const { return total_bytes_size_; }
-
-  Error error() const { return error_; }
-
-  static bool ShouldBeShortcut(const std::vector<DataElement>& items,
-                               size_t memory_available);
-
- private:
-  static void ComputeHandleSizes(uint64_t total_memory_size,
-                                 size_t max_segment_size,
-                                 std::vector<size_t>* segment_sizes);
-
-  Error error_;
-
-  // We use the same vector for shared memory handle sizes and file handle sizes
-  // because we only use one for any strategy. The size of the handles is capped
-  // by the |max_file_size| argument in Initialize, so we can just use size_t.
-  std::vector<size_t> handle_sizes_;
-
-  uint64_t total_bytes_size_;
-  std::vector<RendererMemoryItemRequest> requests_;
-  scoped_ptr<BlobDataBuilder> builder_;
-
-  DISALLOW_COPY_AND_ASSIGN(BlobAsyncTransportStrategy);
-};
-
-}  // namespace storage
-
-#endif  // STORAGE_BROWSER_BLOB_BLOB_ASYNC_TRANSPORT_STRATEGY_H_