gpu/command_buffer/common/id_allocator.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 // This file contains the definition of the IdAllocator class.
   6
   7 #ifndef GPU_COMMAND_BUFFER_CLIENT_ID_ALLOCATOR_H_
   8 #define GPU_COMMAND_BUFFER_CLIENT_ID_ALLOCATOR_H_
   9
  10 #include <stdint.h>
  11
  12 #include <set>
  13 #include <utility>
  14
  15 #include "base/compiler_specific.h"
  16 #include "base/macros.h"
  17 #include "gpu/gpu_export.h"
  18
  19 namespace gpu {
  20
  21 // A resource ID, key to the resource maps.
  22 typedef uint32_t ResourceId;
  23 // Invalid resource ID.
  24 static const ResourceId kInvalidResource = 0u;
  25
  26 // A class to manage the allocation of resource IDs.
  27 class GPU_EXPORT IdAllocator {
  28  public:
  29   IdAllocator();
  30   ~IdAllocator();
  31
  32   // Allocates a new resource ID.
  33   ResourceId AllocateID();
  34
  35   // Allocates an Id starting at or above desired_id.
  36   // Note: may wrap if it starts near limit.
  37   ResourceId AllocateIDAtOrAbove(ResourceId desired_id);
  38
  39   // Marks an id as used. Returns false if id was already used.
  40   bool MarkAsUsed(ResourceId id);
  41
  42   // Frees a resource ID.
  43   void FreeID(ResourceId id);
  44
  45   // Checks whether or not a resource ID is in use.
  46   bool InUse(ResourceId id) const;
  47
  48  private:
  49   // TODO(gman): This would work much better with ranges or a hash table.
  50   typedef std::set<ResourceId> ResourceIdSet;
  51
  52   // The highest ID on the used list.
  53   ResourceId LastUsedId() const;
  54
  55   // Lowest ID that isn't on the used list. This is slow, use as a last resort.
  56   ResourceId FindFirstUnusedId() const;
  57
  58   ResourceIdSet used_ids_;
  59   ResourceIdSet free_ids_;
  60
  61   DISALLOW_COPY_AND_ASSIGN(IdAllocator);
  62 };
  63
  64 }  // namespace gpu
  65
  66 #endif  // GPU_COMMAND_BUFFER_CLIENT_ID_ALLOCATOR_H_