gpu/command_buffer/common/id_allocator.cc

   1 // Copyright (c) 2011 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 implementation of IdAllocator.
   6
   7 #include "gpu/command_buffer/common/id_allocator.h"
   8
   9 #include "base/logging.h"
  10
  11 namespace gpu {
  12
  13 IdAllocatorInterface::~IdAllocatorInterface() {
  14 }
  15
  16 IdAllocator::IdAllocator() {}
  17
  18 IdAllocator::~IdAllocator() {}
  19
  20 ResourceId IdAllocator::AllocateID() {
  21   ResourceId id;
  22   ResourceIdSet::iterator iter = free_ids_.begin();
  23   if (iter != free_ids_.end()) {
  24     id = *iter;
  25   } else {
  26     id = LastUsedId() + 1;
  27     if (!id) {
  28       // We wrapped around to 0.
  29       id = FindFirstUnusedId();
  30     }
  31   }
  32   MarkAsUsed(id);
  33   return id;
  34 }
  35
  36 ResourceId IdAllocator::AllocateIDAtOrAbove(ResourceId desired_id) {
  37   ResourceId id;
  38   ResourceIdSet::iterator iter = free_ids_.lower_bound(desired_id);
  39   if (iter != free_ids_.end()) {
  40     id = *iter;
  41   } else if (LastUsedId() < desired_id) {
  42     id = desired_id;
  43   } else {
  44     id = LastUsedId() + 1;
  45     if (!id) {
  46       // We wrapped around to 0.
  47       id = FindFirstUnusedId();
  48     }
  49   }
  50   MarkAsUsed(id);
  51   return id;
  52 }
  53
  54 bool IdAllocator::MarkAsUsed(ResourceId id) {
  55   DCHECK(id);
  56   free_ids_.erase(id);
  57   std::pair<ResourceIdSet::iterator, bool> result = used_ids_.insert(id);
  58   return result.second;
  59 }
  60
  61 void IdAllocator::FreeID(ResourceId id) {
  62   if (id) {
  63     used_ids_.erase(id);
  64     free_ids_.insert(id);
  65   }
  66 }
  67
  68 bool IdAllocator::InUse(ResourceId id) const {
  69   return id == kInvalidResource || used_ids_.find(id) != used_ids_.end();
  70 }
  71
  72 ResourceId IdAllocator::LastUsedId() const {
  73   if (used_ids_.empty()) {
  74     return 0u;
  75   } else {
  76     return *used_ids_.rbegin();
  77   }
  78 }
  79
  80 ResourceId IdAllocator::FindFirstUnusedId() const {
  81   ResourceId id = 1;
  82   for (ResourceIdSet::const_iterator it = used_ids_.begin();
  83        it != used_ids_.end(); ++it) {
  84     if ((*it) != id) {
  85       return id;
  86     }
  87     ++id;
  88   }
  89   return id;
  90 }
  91
  92 NonReusedIdAllocator::NonReusedIdAllocator() : last_id_(0) {
  93 }
  94
  95 NonReusedIdAllocator::~NonReusedIdAllocator() {
  96 }
  97
  98 ResourceId NonReusedIdAllocator::AllocateID() {
  99   return ++last_id_;
 100 }
 101
 102 ResourceId NonReusedIdAllocator::AllocateIDAtOrAbove(ResourceId desired_id) {
 103   if (desired_id > last_id_)
 104     last_id_ = desired_id;
 105
 106   return ++last_id_;
 107 }
 108
 109 bool NonReusedIdAllocator::MarkAsUsed(ResourceId id) {
 110   NOTREACHED();
 111   return false;
 112 }
 113
 114 void NonReusedIdAllocator::FreeID(ResourceId id) {
 115 }
 116
 117 bool NonReusedIdAllocator::InUse(ResourceId id) const {
 118   NOTREACHED();
 119   return false;
 120 }
 121
 122 }  // namespace gpu