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         : num_entries(0),
  24           get_offset(0),
  25           put_offset(0),
  26           token(-1),
  27           error(error::kNoError),
  28           context_lost_reason(error::kUnknown),
  29           generation(0) {
  30     }
  31
  32     // Size of the command buffer in command buffer entries.
  33     int32 num_entries;
  34
  35     // The offset (in entries) from which the reader is reading.
  36     int32 get_offset;
  37
  38     // The offset (in entries) at which the writer is writing.
  39     int32 put_offset;
  40
  41     // The current token value. This is used by the writer to defer
  42     // changes to shared memory objects until the reader has reached a certain
  43     // point in the command buffer. The reader is responsible for updating the
  44     // token value, for example in response to an asynchronous set token command
  45     // embedded in the command buffer. The default token value is zero.
  46     int32 token;
  47
  48     // Error status.
  49     error::Error error;
  50
  51     // Lost context detail information.
  52     error::ContextLostReason context_lost_reason;
  53
  54     // Generation index of this state. The generation index is incremented every
  55     // time a new state is retrieved from the command processor, so that
  56     // consistency can be kept even if IPC messages are processed out-of-order.
  57     uint32 generation;
  58   };
  59
  60   struct ConsoleMessage {
  61     // An user supplied id.
  62     int32 id;
  63     // The message.
  64     std::string message;
  65   };
  66
  67   CommandBuffer() {
  68   }
  69
  70   virtual ~CommandBuffer() {
  71   }
  72
  73   // Check if a value is between a start and end value, inclusive, allowing
  74   // for wrapping if start > end.
  75   static bool InRange(int32 start, int32 end, int32 value) {
  76     if (start <= end)
  77       return start <= value && value <= end;
  78     else
  79       return start <= value || value <= end;
  80   }
  81
  82   // Initialize the command buffer with the given size.
  83   virtual bool Initialize() = 0;
  84
  85   // Returns the last state without synchronizing with the service.
  86   virtual State GetLastState() = 0;
  87
  88   // Returns the last token without synchronizing with the service. Note that
  89   // while you could just call GetLastState().token, GetLastState needs to be
  90   // fast as it is called for every command where GetLastToken is only called
  91   // by code that needs to know the last token so it can be slower but more up
  92   // to date than GetLastState.
  93   virtual int32 GetLastToken() = 0;
  94
  95   // The writer calls this to update its put offset. This ensures the reader
  96   // sees the latest added commands, and will eventually process them. On the
  97   // service side, commands are processed up to the given put_offset before
  98   // subsequent Flushes on the same GpuChannel.
  99   virtual void Flush(int32 put_offset) = 0;
 100
 101   // The writer calls this to wait until the current token is within a
 102   // specific range, inclusive. Can return early if an error is generated.
 103   virtual void WaitForTokenInRange(int32 start, int32 end) = 0;
 104
 105   // The writer calls this to wait until the current get offset is within a
 106   // specific range, inclusive. Can return early if an error is generated.
 107   virtual void WaitForGetOffsetInRange(int32 start, int32 end) = 0;
 108
 109   // Sets the buffer commands are read from.
 110   // Also resets the get and put offsets to 0.
 111   virtual void SetGetBuffer(int32 transfer_buffer_id) = 0;
 112
 113   // Create a transfer buffer of the given size. Returns its ID or -1 on
 114   // error.
 115   virtual scoped_refptr<gpu::Buffer> CreateTransferBuffer(size_t size,
 116                                                           int32* id) = 0;
 117
 118   // Destroy a transfer buffer. The ID must be positive.
 119   virtual void DestroyTransferBuffer(int32 id) = 0;
 120
 121 // The NaCl Win64 build only really needs the struct definitions above; having
 122 // GetLastError declared would mean we'd have to also define it, and pull more
 123 // of gpu in to the NaCl Win64 build.
 124 #if !defined(NACL_WIN64)
 125   // TODO(apatrick): this is a temporary optimization while skia is calling
 126   // RendererGLContext::MakeCurrent prior to every GL call. It saves returning 6
 127   // ints redundantly when only the error is needed for the CommandBufferProxy
 128   // implementation.
 129   virtual error::Error GetLastError();
 130 #endif
 131
 132  private:
 133   DISALLOW_COPY_AND_ASSIGN(CommandBuffer);
 134 };
 135
 136 }  // namespace gpu
 137
 138 #endif  // GPU_COMMAND_BUFFER_COMMON_COMMAND_BUFFER_H_