1    :  // Copyright 2012 Google Inc. All Rights Reserved.
   2    :  //
   3    :  // Licensed under the Apache License, Version 2.0 (the "License");
   4    :  // you may not use this file except in compliance with the License.
   5    :  // You may obtain a copy of the License at
   6    :  //
   7    :  //     http://www.apache.org/licenses/LICENSE-2.0
   8    :  //
   9    :  // Unless required by applicable law or agreed to in writing, software
  10    :  // distributed under the License is distributed on an "AS IS" BASIS,
  11    :  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12    :  // See the License for the specific language governing permissions and
  13    :  // limitations under the License.
  14    :  //
  15    :  // This file defines the trace::service::Buffer and BufferPool
  16    :  // structures, which are used to represent the shared memory buffers
  17    :  // used by the call_trace service.
  18    :  
  19    :  #ifndef SYZYGY_TRACE_SERVICE_BUFFER_POOL_H_
  20    :  #define SYZYGY_TRACE_SERVICE_BUFFER_POOL_H_
  21    :  
  22    :  #include <deque>
  23    :  #include <map>
  24    :  #include <utility>
  25    :  #include <vector>
  26    :  
  27    :  #include "base/basictypes.h"
  28    :  #include "base/win/scoped_handle.h"
  29    :  #include "syzygy/trace/rpc/call_trace_rpc.h"
  30    :  
  31    :  namespace trace {
  32    :  namespace service {
  33    :  
  34    :  // Forward declaration.
  35    :  class Session;
  36    :  
  37    :  // A Buffer extends the RPC defined CallTraceBuffer structure with the
  38    :  // extra bits needed by the internals of the Call Trace service.
  39    :  struct Buffer : public ::CallTraceBuffer {
  40    :    // A buffer is always in one of the following states.
  41    :    enum BufferState {
  42    :      kAvailable,
  43    :      kInUse,
  44    :      kPendingWrite,
  45    :      kBufferStateMax,
  46    :    };
  47    :  
  48    :    // Type used to identify a buffer. The first and second values in the
  49    :    // pair are the numeric id of the shared memory handle and the buffer
  50    :    // offset, respectively. See the GetID() method, below.
  51    :    typedef std::pair<unsigned long, unsigned long> ID;
  52    :  
  53    :    // Utility to get the ID for any buffer instance.
  54  E :    static ID GetID(const CallTraceBuffer& buffer) {
  55  E :      return std::make_pair(buffer.shared_memory_handle, buffer.buffer_offset);
  56  E :    }
  57    :  
  58    :    // We augment the buffer with some additional state.
  59    :    Session* session;
  60    :    uint8* data_ptr;
  61    :    BufferState state;
  62    :  };
  63    :  
  64    :  // A BufferPool manages a collection of buffers that all belong to the same
  65    :  // shared memory allocation.
  66    :  class BufferPool {
  67    :   public:
  68    :    BufferPool();
  69    :    ~BufferPool();
  70    :  
  71    :    // Allocates and maps a shared memory segment sufficiently large for
  72    :    // @p num_buffers, each of size @p buffer_size.
  73    :    bool Init(Session* session, size_t num_buffers, size_t buffer_size);
  74    :  
  75    :    // Updates each buffer in buffers_ with @p client_handle, which should be
  76    :    // a copy of handle_, valid in the client process these buffers are to be
  77    :    // shared with.
  78    :    // @p num_buffers, each of size @p buffer_size.
  79    :    void SetClientHandle(HANDLE client_handle);
  80    :  
  81  E :    Buffer* begin() { return &buffers_[0]; }
  82  E :    Buffer* end() { return begin() + buffers_.size(); }
  83    :  
  84    :    // Returns this pools shared memory segment handle.
  85  E :    HANDLE handle() const { return handle_.Get(); }
  86    :  
  87    :   private:
  88    :    typedef std::vector<Buffer> BufferCollection;
  89    :    // Sadly ScopedHandle is not const correct.
  90    :    mutable base::win::ScopedHandle handle_;
  91    :    uint8* base_ptr_;
  92    :    BufferCollection buffers_;
  93    :  
  94    :    DISALLOW_COPY_AND_ASSIGN(BufferPool);
  95    :  };
  96    :  
  97    :  }  // namespace service
  98    :  }  // namespace trace
  99    :  
 100    :  #endif  // SYZYGY_TRACE_SERVICE_BUFFER_POOL_H_