[BlobAsync] Patch 2: Common Constants

storage/common/data_element.h

 // 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.
 
 #ifndef STORAGE_COMMON_DATA_ELEMENT_H_
 #define STORAGE_COMMON_DATA_ELEMENT_H_
 
+#include <ostream>
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/time/time.h"
 #include "storage/common/storage_common_export.h"
 #include "url/gurl.h"
 
 namespace storage {
 
 // Represents a base Web data element. This could be either one of
 // bytes, file or blob data.
 class STORAGE_COMMON_EXPORT DataElement {
  public:
   enum Type {
     TYPE_UNKNOWN = -1,
     TYPE_BYTES,
+    // Only used with BlobStorageMsg_StartBuildingBlob
+    TYPE_BYTES_DESCRIPTION,
     TYPE_FILE,
     TYPE_BLOB,
     TYPE_FILE_FILESYSTEM,
     TYPE_DISK_CACHE_ENTRY,
   };
 
   DataElement();
   ~DataElement();
 
   Type type() const { return type_; }
   const char* bytes() const { return bytes_ ? bytes_ : &buf_[0]; }
   const base::FilePath& path() const { return path_; }
   const GURL& filesystem_url() const { return filesystem_url_; }
   const std::string& blob_uuid() const { return blob_uuid_; }
   uint64 offset() const { return offset_; }
   uint64 length() const { return length_; }
   const base::Time& expected_modification_time() const {
     return expected_modification_time_;
   }
 
+  // For use with SetToAllocatedBytes. Should only be used after calling
+  // SetToAllocatedBytes.
+  char* mutable_bytes() { return &buf_[0]; }
+
   // Sets TYPE_BYTES data. This copies the given data into the element.
   void SetToBytes(const char* bytes, int bytes_len) {
     type_ = TYPE_BYTES;
+    bytes_ = nullptr;
     buf_.assign(bytes, bytes + bytes_len);
     length_ = buf_.size();
   }
 
   // Sets TYPE_BYTES data, and clears the internal bytes buffer.
   // For use with AppendBytes.
   void SetToEmptyBytes() {
     type_ = TYPE_BYTES;
     buf_.clear();
     length_ = 0;
     bytes_ = nullptr;
   }
 
   // Copies and appends the given data into the element. SetToEmptyBytes or
   // SetToBytes must be called before this method.
   void AppendBytes(const char* bytes, int bytes_len) {
     DCHECK_EQ(type_, TYPE_BYTES);
     DCHECK_NE(length_, kuint64max);
     DCHECK(!bytes_);
     buf_.insert(buf_.end(), bytes, bytes + bytes_len);
     length_ = buf_.size();
   }
 
+  void SetToBytesDescription(size_t bytes_len) {
+    type_ = TYPE_BYTES_DESCRIPTION;
+    bytes_ = nullptr;
+    length_ = bytes_len;
+  }
+
   // Sets TYPE_BYTES data. This does NOT copy the given data and the caller
   // should make sure the data is alive when this element is accessed.
   // You cannot use AppendBytes with this method.
   void SetToSharedBytes(const char* bytes, int bytes_len) {
     type_ = TYPE_BYTES;
     bytes_ = bytes;
     length_ = bytes_len;
   }
 
+  // Sets TYPE_BYTES data. This allocates the space for the bytes in the
+  // internal vector but does not populate it with anything.  The caller can
+  // then use the bytes() method to access this buffer and populate it.
+  void SetToAllocatedBytes(size_t bytes_len) {
+    type_ = TYPE_BYTES;
+    bytes_ = nullptr;
+    buf_.resize(bytes_len);
+    length_ = bytes_len;
+  }
+
   // Sets TYPE_FILE data.
   void SetToFilePath(const base::FilePath& path) {
     SetToFilePathRange(path, 0, kuint64max, base::Time());
   }
 
   // Sets TYPE_BLOB data.
   void SetToBlob(const std::string& uuid) {
     SetToBlobRange(uuid, 0, kuint64max);
   }
 
@@ skipping 19 matching lines @@
   std::vector<char> buf_;  // For TYPE_BYTES.
   const char* bytes_;  // For TYPE_BYTES.
   base::FilePath path_;  // For TYPE_FILE.
   GURL filesystem_url_;  // For TYPE_FILE_FILESYSTEM.
   std::string blob_uuid_;
   uint64 offset_;
   uint64 length_;
   base::Time expected_modification_time_;
 };
 
+STORAGE_COMMON_EXPORT std::ostream& operator<<(std::ostream& os,
+                                               const DataElement& x);
+
 #if defined(UNIT_TEST)
 inline bool operator==(const DataElement& a, const DataElement& b) {
   if (a.type() != b.type() ||
       a.offset() != b.offset() ||
       a.length() != b.length())
     return false;
   switch (a.type()) {
     case DataElement::TYPE_BYTES:
       return memcmp(a.bytes(), b.bytes(), b.length()) == 0;
     case DataElement::TYPE_FILE:
       return a.path() == b.path() &&
              a.expected_modification_time() == b.expected_modification_time();
     case DataElement::TYPE_BLOB:
       return a.blob_uuid() == b.blob_uuid();
     case DataElement::TYPE_FILE_FILESYSTEM:
       return a.filesystem_url() == b.filesystem_url();
     case DataElement::TYPE_DISK_CACHE_ENTRY:
       // We compare only length and offset; we trust the entry itself was
       // compared at some higher level such as in BlobDataItem.
       return true;
+    case DataElement::TYPE_BYTES_DESCRIPTION:
+      return a.length() == b.length();

[michaeln, 2015/10/20 01:16:14]

you can return true here since lengths are compared above

[dmurph, 2015/10/20 18:28:27]

Nice catch.

     case DataElement::TYPE_UNKNOWN:
       NOTREACHED();
       return false;
   }
   return false;
 }
 
 inline bool operator!=(const DataElement& a, const DataElement& b) {
   return !(a == b);
 }
+
 #endif  // defined(UNIT_TEST)
 
 }  // namespace storage
 
 #endif  // STORAGE_COMMON_DATA_ELEMENT_H_