ppapi/shared_impl/file_io_state_manager.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 PPAPI_SHARED_IMPL_FILE_IO_STATE_MANAGER_H_
   6 #define PPAPI_SHARED_IMPL_FILE_IO_STATE_MANAGER_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/compiler_specific.h"
  10 #include "ppapi/c/pp_stdint.h"
  11 #include "ppapi/shared_impl/ppapi_shared_export.h"
  12
  13 namespace ppapi {
  14
  15 // FileIOStateManager is a helper class that maintains the state of operations.
  16 // For example, some operations are mutually exclusive, meaning that an
  17 // operation could be rejected because of the current pending operation. Also,
  18 // most of the operations only work when the file has been opened.
  19 class PPAPI_SHARED_EXPORT FileIOStateManager {
  20  public:
  21   FileIOStateManager();
  22   ~FileIOStateManager();
  23
  24   enum OperationType {
  25     // There is no pending operation right now.
  26     OPERATION_NONE,
  27
  28     // If there are pending reads, any other kind of async operation is not
  29     // allowed.
  30     OPERATION_READ,
  31
  32     // If there are pending writes, any other kind of async operation is not
  33     // allowed.
  34     OPERATION_WRITE,
  35
  36     // If there is a pending operation that is neither read nor write, no
  37     // further async operation is allowed.
  38     OPERATION_EXCLUSIVE
  39   };
  40
  41   OperationType get_pending_operation() const { return pending_op_; }
  42
  43   void SetOpenSucceed();
  44
  45   // Called at the beginning of each operation. It is responsible to make sure
  46   // that state is correct. For example, some operations are only valid after
  47   // the file is opened, or operations might need to run exclusively.
  48   //
  49   // It returns |PP_OK| on success, or |PP_ERROR_...| for various reasons.
  50   int32_t CheckOperationState(OperationType new_op, bool should_be_open);
  51
  52   // Marks the state of current operations as started or finished.
  53   void SetPendingOperation(OperationType op);
  54   void SetOperationFinished();
  55
  56  private:
  57   int num_pending_ops_;
  58   OperationType pending_op_;
  59
  60   // Set to true when the file has been successfully opened.
  61   bool file_open_;
  62
  63   DISALLOW_COPY_AND_ASSIGN(FileIOStateManager);
  64 };
  65
  66 }  // namespace ppapi
  67
  68 #endif  // PPAPI_SHARED_IMPL_FILE_IO_STATE_MANAGER_H_