content/child/blob_storage/blob_consolidation.h

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_CHILD_BLOB_STORAGE_BLOB_CONSOLIDATION_H_
   6 #define CONTENT_CHILD_BLOB_STORAGE_BLOB_CONSOLIDATION_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/logging.h"
  12 #include "base/macros.h"
  13 #include "base/memory/scoped_ptr.h"
  14 #include "content/common/content_export.h"
  15 #include "storage/common/data_element.h"
  16 #include "third_party/WebKit/public/platform/WebThreadSafeData.h"
  17
  18 namespace content {
  19
  20 // This class facilitates the consolidation of memory items in blobs. No memory
  21 // is copied to store items in this object. Instead, the memory is copied into
  22 // the external char* array given to the ReadMemory method.
  23 // Features:
  24 // * Add_Item methods for building the blob.
  25 // * consolidated_items for getting the consolidated items. This is
  26 //   used to describe the blob to the browser.
  27 // * total_memory to get the total memory size of the blob.
  28 // * ReadMemory for reading arbitrary memory from any consolidated item.
  29 //
  30 // NOTE: this class does not do memory accounting or garbage collecting. The
  31 // memory for the blob sticks around until this class is destructed.
  32 class CONTENT_EXPORT BlobConsolidation {
  33  public:
  34   enum class ReadStatus {
  35     ERROR_UNKNOWN,
  36     ERROR_WRONG_TYPE,
  37     ERROR_OUT_OF_BOUNDS,
  38     OK
  39   };
  40   struct ConsolidatedItem {
  41     ConsolidatedItem();
  42     ConsolidatedItem(storage::DataElement::Type type,
  43                      uint64_t offset,
  44                      uint64_t length);
  45     ~ConsolidatedItem();
  46
  47     storage::DataElement::Type type;
  48     uint64_t offset;
  49     uint64_t length;
  50
  51     base::FilePath path;                // For TYPE_FILE.
  52     GURL filesystem_url;                // For TYPE_FILE_FILESYSTEM.
  53     double expected_modification_time;  // For TYPE_FILE, TYPE_FILE_FILESYSTEM.
  54     std::string blob_uuid;              // For TYPE_BLOB.
  55     // Only populated if len(items) > 1.  Used for binary search.
  56     // Since the offset of the first item is always 0, we exclude this.
  57     std::vector<size_t> offsets;                 // For TYPE_BYTES.
  58     std::vector<blink::WebThreadSafeData> data;  // For TYPE_BYTES.
  59   };
  60
  61   BlobConsolidation();
  62   ~BlobConsolidation();
  63
  64   void AddDataItem(const blink::WebThreadSafeData& data);
  65   void AddFileItem(const base::FilePath& path,
  66                    uint64_t offset,
  67                    uint64_t length,
  68                    double expected_modification_time);
  69   void AddBlobItem(const std::string& uuid, uint64_t offset, uint64_t length);
  70   void AddFileSystemItem(const GURL& url,
  71                          uint64_t offset,
  72                          uint64_t length,
  73                          double expected_modification_time);
  74
  75   // These are the resulting consolidated items, constructed from the Add*
  76   // methods. This configuration is used to describe the data to the browser,
  77   // even though one consolidated memory items can contain multiple data parts.
  78   const std::vector<ConsolidatedItem>& consolidated_items() const {
  79     return consolidated_items_;
  80   }
  81
  82   size_t total_memory() const { return total_memory_; }
  83
  84   // Reads memory from the given item into the given buffer. Returns:
  85   // * ReadStatus::ERROR if the state or arguments are invalid (see error log),
  86   // * ReadStatus::ERROR_WRONG_TYPE if the item at the index isn't memory,
  87   // * ReadStatus::ERROR_OUT_OF_BOUNDS if index, offset, or size are invalid,
  88   // * ReadStatus::DONE if the memory has been successfully read.
  89   // Precondition: memory_out must be a valid pointer to memory with a size of
  90   //               at least consolidated_size.
  91   ReadStatus ReadMemory(size_t consolidated_item_index,
  92                         size_t consolidated_offset,
  93                         size_t consolidated_size,
  94                         void* memory_out);
  95
  96  private:
  97   size_t total_memory_;
  98   std::vector<ConsolidatedItem> consolidated_items_;
  99
 100   DISALLOW_COPY_AND_ASSIGN(BlobConsolidation);
 101 };
 102
 103 }  // namespace content
 104 #endif  // CONTENT_CHILD_BLOB_STORAGE_BLOB_CONSOLIDATION_H_