net/base/upload_element_reader.h

   1 // Copyright (c) 2012 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 NET_BASE_UPLOAD_ELEMENT_READER_H_
   6 #define NET_BASE_UPLOAD_ELEMENT_READER_H_
   7
   8 #include "base/basictypes.h"
   9 #include "net/base/completion_callback.h"
  10 #include "net/base/net_export.h"
  11
  12 namespace net {
  13
  14 class IOBuffer;
  15 class UploadBytesElementReader;
  16 class UploadDiskCacheEntryElementReader;
  17 class UploadFileElementReader;
  18
  19 // An interface to read an upload data element.
  20 class NET_EXPORT UploadElementReader {
  21  public:
  22   UploadElementReader() {}
  23   virtual ~UploadElementReader() {}
  24
  25   // Returns this instance's pointer as UploadDiskCacheEntryElementReader when
  26   // possible, otherwise returns nullptr.
  27   virtual const UploadDiskCacheEntryElementReader*
  28   AsDiskCacheEntryReaderForTests() const;
  29
  30   // Returns this instance's pointer as UploadBytesElementReader when possible,
  31   // otherwise returns NULL.
  32   virtual const UploadBytesElementReader* AsBytesReader() const;
  33
  34   // Returns this instance's pointer as UploadFileElementReader when possible,
  35   // otherwise returns NULL.
  36   virtual const UploadFileElementReader* AsFileReader() const;
  37
  38   // Initializes the instance synchronously when possible, otherwise does
  39   // initialization aynschronously, returns ERR_IO_PENDING and runs callback.
  40   // Calling this method again after a Init() success results in resetting the
  41   // state.
  42   virtual int Init(const CompletionCallback& callback) = 0;
  43
  44   // Returns the byte-length of the element. For files that do not exist, 0
  45   // is returned. This is done for consistency with Mozilla.
  46   virtual uint64_t GetContentLength() const = 0;
  47
  48   // Returns the number of bytes remaining to read.
  49   virtual uint64_t BytesRemaining() const = 0;
  50
  51   // Returns true if the upload element is entirely in memory.
  52   // The default implementation returns false.
  53   virtual bool IsInMemory() const;
  54
  55   // Reads up to |buf_length| bytes synchronously and returns the number of
  56   // bytes read or error code when possible, otherwise, returns ERR_IO_PENDING
  57   // and runs |callback| with the result. |buf_length| must be greater than 0.
  58   virtual int Read(IOBuffer* buf,
  59                    int buf_length,
  60                    const CompletionCallback& callback) = 0;
  61
  62  private:
  63   DISALLOW_COPY_AND_ASSIGN(UploadElementReader);
  64 };
  65
  66 }  // namespace net
  67
  68 #endif  // NET_BASE_UPLOAD_ELEMENT_READER_H_