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      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_
     69