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// Copyright 2023 The Dawn Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <algorithm>
#include <functional>
#include <limits>
#include <utility>
#include "dawn/fuzzers/lpmfuzz/DawnLPMConstants_autogen.h"
#include "dawn/fuzzers/lpmfuzz/DawnLPMObjectStore.h"
#include "dawn/fuzzers/lpmfuzz/DawnLPMSerializer_autogen.h"
#include "dawn/wire/ObjectHandle.h"
namespace dawn::wire {
DawnLPMObjectStore::DawnLPMObjectStore() {
mCurrentId = 1;
}
ObjectHandle DawnLPMObjectStore::ReserveHandle() {
if (mFreeHandles.empty()) {
Insert(mCurrentId);
return {mCurrentId++, 0};
}
ObjectHandle handle = mFreeHandles.back();
mFreeHandles.pop_back();
Insert(handle.id);
return handle;
}
void DawnLPMObjectStore::Insert(ObjectId id) {
std::vector<ObjectId>::iterator iter =
std::lower_bound(mObjects.begin(), mObjects.end(), id, std::greater<ObjectId>());
mObjects.insert(iter, id);
}
void DawnLPMObjectStore::Free(ObjectId id) {
if (id == DawnLPMFuzzer::kInvalidObjectId) {
return;
}
for (size_t i = 0; i < mObjects.size(); i++) {
if (mObjects[i] == id) {
mFreeHandles.push_back({id, 0});
mObjects.erase(mObjects.begin() + i);
}
}
}
/*
* Consistent hashing inspired map for fuzzer state.
* If we store the Dawn objects in a hash table mapping FuzzInt -> ObjectId
* then it would be highly unlikely that any subsequence DestroyObject command
* would come up with an ID that would correspond to a valid ObjectId in the
* hash table.
*
* One solution is to modulo the FuzzInt with the length of the hash table, but
* it does not work well with libfuzzer's minimization techniques because
* deleting a single ObjectId from the hash table changes the index of every
* entry from then on.
*
* So we use consistent hashing. we take the entry in the table that
* has the next highest id (wrapping when there is no higher entry).
*/
ObjectId DawnLPMObjectStore::Lookup(uint32_t id) const {
// CreateBindGroup relies on sending invalid object ids
if (id == DawnLPMFuzzer::kInvalidObjectId) {
return 0;
}
auto iter = std::lower_bound(mObjects.begin(), mObjects.end(), id, std::greater<ObjectId>());
if (iter != mObjects.end()) {
return *iter;
}
// Wrap to 0
iter = std::lower_bound(mObjects.begin(), mObjects.end(), 0, std::greater<ObjectId>());
if (iter != mObjects.end()) {
return *iter;
}
return 0;
}
size_t DawnLPMObjectStore::Size() const {
return mObjects.size();
}
} // namespace dawn::wire