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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// This file contains the implementation of IdAllocator.
#include "gpu/command_buffer/common/id_allocator.h"
#include "base/logging.h"
namespace gpu {
IdAllocator::IdAllocator() {}
IdAllocator::~IdAllocator() {}
ResourceId IdAllocator::AllocateID() {
ResourceId id;
ResourceIdSet::iterator iter = free_ids_.begin();
if (iter != free_ids_.end()) {
id = *iter;
} else {
id = LastUsedId() + 1;
if (!id) {
// We wrapped around to 0.
id = FindFirstUnusedId();
}
}
MarkAsUsed(id);
return id;
}
ResourceId IdAllocator::AllocateIDAtOrAbove(ResourceId desired_id) {
ResourceId id;
ResourceIdSet::iterator iter = free_ids_.lower_bound(desired_id);
if (iter != free_ids_.end()) {
id = *iter;
} else if (LastUsedId() < desired_id) {
id = desired_id;
} else {
id = LastUsedId() + 1;
if (!id) {
// We wrapped around to 0.
id = FindFirstUnusedId();
}
}
MarkAsUsed(id);
return id;
}
bool IdAllocator::MarkAsUsed(ResourceId id) {
DCHECK(id);
free_ids_.erase(id);
std::pair<ResourceIdSet::iterator, bool> result = used_ids_.insert(id);
return result.second;
}
void IdAllocator::FreeID(ResourceId id) {
if (id) {
used_ids_.erase(id);
free_ids_.insert(id);
}
}
bool IdAllocator::InUse(ResourceId id) const {
return id == kInvalidResource || used_ids_.find(id) != used_ids_.end();
}
ResourceId IdAllocator::LastUsedId() const {
if (used_ids_.empty()) {
return 0u;
} else {
return *used_ids_.rbegin();
}
}
ResourceId IdAllocator::FindFirstUnusedId() const {
ResourceId id = 1;
for (ResourceIdSet::const_iterator it = used_ids_.begin();
it != used_ids_.end(); ++it) {
if ((*it) != id) {
return id;
}
++id;
}
return id;
}
} // namespace gpu
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