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 <set>
  11 #include <utility>
  12
  13 #include "base/compiler_specific.h"
  14 #include "gpu/command_buffer/common/types.h"
  15 #include "gpu/gpu_export.h"
  16
  17 namespace gpu {
  18
  19 // A resource ID, key to the resource maps.
  20 typedef uint32 ResourceId;
  21 // Invalid resource ID.
  22 static const ResourceId kInvalidResource = 0u;
  23
  24 class GPU_EXPORT IdAllocatorInterface {
  25  public:
  26   virtual ~IdAllocatorInterface();
  27
  28   // Allocates a new resource ID.
  29   virtual ResourceId AllocateID() = 0;
  30
  31   // Allocates an Id starting at or above desired_id.
  32   // Note: may wrap if it starts near limit.
  33   virtual ResourceId AllocateIDAtOrAbove(ResourceId desired_id) = 0;
  34
  35   // Marks an id as used. Returns false if id was already used.
  36   virtual bool MarkAsUsed(ResourceId id) = 0;
  37
  38   // Frees a resource ID.
  39   virtual void FreeID(ResourceId id) = 0;
  40
  41   // Checks whether or not a resource ID is in use.
  42   virtual bool InUse(ResourceId id) const = 0;
  43 };
  44
  45 // A class to manage the allocation of resource IDs.
  46 class GPU_EXPORT IdAllocator : public IdAllocatorInterface {
  47  public:
  48   IdAllocator();
  49   virtual ~IdAllocator();
  50
  51   // Implement IdAllocatorInterface.
  52   virtual ResourceId AllocateID() OVERRIDE;
  53   virtual ResourceId AllocateIDAtOrAbove(ResourceId desired_id) OVERRIDE;
  54   virtual bool MarkAsUsed(ResourceId id) OVERRIDE;
  55   virtual void FreeID(ResourceId id) OVERRIDE;
  56   virtual bool InUse(ResourceId id) const OVERRIDE;
  57
  58  private:
  59   // TODO(gman): This would work much better with ranges or a hash table.
  60   typedef std::set<ResourceId> ResourceIdSet;
  61
  62   // The highest ID on the used list.
  63   ResourceId LastUsedId() const;
  64
  65   // Lowest ID that isn't on the used list. This is slow, use as a last resort.
  66   ResourceId FindFirstUnusedId() const;
  67
  68   ResourceIdSet used_ids_;
  69   ResourceIdSet free_ids_;
  70
  71   DISALLOW_COPY_AND_ASSIGN(IdAllocator);
  72 };
  73
  74 // A class to manage the allocation of resource IDs that are never reused. This
  75 // implementation does not track which IDs are currently used. It is useful for
  76 // shared and programs which cannot be implicitly created by binding a
  77 // previously unused ID.
  78 class NonReusedIdAllocator : public IdAllocatorInterface {
  79  public:
  80   NonReusedIdAllocator();
  81   virtual ~NonReusedIdAllocator();
  82
  83   // Implement IdAllocatorInterface.
  84   virtual ResourceId AllocateID() OVERRIDE;
  85   virtual ResourceId AllocateIDAtOrAbove(ResourceId desired_id) OVERRIDE;
  86   virtual bool MarkAsUsed(ResourceId id) OVERRIDE;
  87   virtual void FreeID(ResourceId id) OVERRIDE;
  88   virtual bool InUse(ResourceId id) const OVERRIDE;
  89
  90  private:
  91   ResourceId last_id_;
  92
  93   DISALLOW_COPY_AND_ASSIGN(NonReusedIdAllocator);
  94 };
  95
  96 }  // namespace gpu
  97
  98 #endif  // GPU_COMMAND_BUFFER_CLIENT_ID_ALLOCATOR_H_