gpu/command_buffer/common/command_buffer.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 GPU_COMMAND_BUFFER_COMMON_COMMAND_BUFFER_H_
   6 #define GPU_COMMAND_BUFFER_COMMON_COMMAND_BUFFER_H_
   7
   8 #include "gpu/command_buffer/common/buffer.h"
   9 #include "gpu/command_buffer/common/constants.h"
  10 #include "gpu/gpu_export.h"
  11
  12 namespace base {
  13 class SharedMemory;
  14 }
  15
  16 namespace gpu {
  17
  18 // Common interface for CommandBuffer implementations.
  19 class GPU_EXPORT CommandBuffer {
  20  public:
  21   struct State {
  22     State()
  23         : get_offset(0),
  24           token(-1),
  25           error(error::kNoError),
  26           context_lost_reason(error::kUnknown),
  27           generation(0) {
  28     }
  29
  30     // The offset (in entries) from which the reader is reading.
  31     int32 get_offset;
  32
  33     // The current token value. This is used by the writer to defer
  34     // changes to shared memory objects until the reader has reached a certain
  35     // point in the command buffer. The reader is responsible for updating the
  36     // token value, for example in response to an asynchronous set token command
  37     // embedded in the command buffer. The default token value is zero.
  38     int32 token;
  39
  40     // Error status.
  41     error::Error error;
  42
  43     // Lost context detail information.
  44     error::ContextLostReason context_lost_reason;
  45
  46     // Generation index of this state. The generation index is incremented every
  47     // time a new state is retrieved from the command processor, so that
  48     // consistency can be kept even if IPC messages are processed out-of-order.
  49     uint32 generation;
  50   };
  51
  52   struct ConsoleMessage {
  53     // An user supplied id.
  54     int32 id;
  55     // The message.
  56     std::string message;
  57   };
  58
  59   CommandBuffer() {
  60   }
  61
  62   virtual ~CommandBuffer() {
  63   }
  64
  65   // Check if a value is between a start and end value, inclusive, allowing
  66   // for wrapping if start > end.
  67   static bool InRange(int32 start, int32 end, int32 value) {
  68     if (start <= end)
  69       return start <= value && value <= end;
  70     else
  71       return start <= value || value <= end;
  72   }
  73
  74   // Initialize the command buffer with the given size.
  75   virtual bool Initialize() = 0;
  76
  77   // Returns the last state without synchronizing with the service.
  78   virtual State GetLastState() = 0;
  79
  80   // Returns the last token without synchronizing with the service. Note that
  81   // while you could just call GetLastState().token, GetLastState needs to be
  82   // fast as it is called for every command where GetLastToken is only called
  83   // by code that needs to know the last token so it can be slower but more up
  84   // to date than GetLastState.
  85   virtual int32 GetLastToken() = 0;
  86
  87   // The writer calls this to update its put offset. This ensures the reader
  88   // sees the latest added commands, and will eventually process them. On the
  89   // service side, commands are processed up to the given put_offset before
  90   // subsequent Flushes on the same GpuChannel.
  91   virtual void Flush(int32 put_offset) = 0;
  92
  93   // As Flush, ensures that on the service side, commands up to put_offset
  94   // are processed but before subsequent commands on the same GpuChannel but
  95   // flushing to the service may be deferred.
  96   virtual void OrderingBarrier(int32 put_offset) = 0;
  97
  98   // The writer calls this to wait until the current token is within a
  99   // specific range, inclusive. Can return early if an error is generated.
 100   virtual void WaitForTokenInRange(int32 start, int32 end) = 0;
 101
 102   // The writer calls this to wait until the current get offset is within a
 103   // specific range, inclusive. Can return early if an error is generated.
 104   virtual void WaitForGetOffsetInRange(int32 start, int32 end) = 0;
 105
 106   // Sets the buffer commands are read from.
 107   // Also resets the get and put offsets to 0.
 108   virtual void SetGetBuffer(int32 transfer_buffer_id) = 0;
 109
 110   // Create a transfer buffer of the given size. Returns its ID or -1 on
 111   // error.
 112   virtual scoped_refptr<gpu::Buffer> CreateTransferBuffer(size_t size,
 113                                                           int32* id) = 0;
 114
 115   // Destroy a transfer buffer. The ID must be positive.
 116   virtual void DestroyTransferBuffer(int32 id) = 0;
 117
 118 // The NaCl Win64 build only really needs the struct definitions above; having
 119 // GetLastError declared would mean we'd have to also define it, and pull more
 120 // of gpu in to the NaCl Win64 build.
 121 #if !defined(NACL_WIN64)
 122   // TODO(apatrick): this is a temporary optimization while skia is calling
 123   // RendererGLContext::MakeCurrent prior to every GL call. It saves returning 6
 124   // ints redundantly when only the error is needed for the CommandBufferProxy
 125   // implementation.
 126   virtual error::Error GetLastError();
 127 #endif
 128
 129  private:
 130   DISALLOW_COPY_AND_ASSIGN(CommandBuffer);
 131 };
 132
 133 }  // namespace gpu
 134
 135 #endif  // GPU_COMMAND_BUFFER_COMMON_COMMAND_BUFFER_H_