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143 lines
4.0 KiB
143 lines
4.0 KiB
/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include "base/Lookup.h"
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#include "base/Stream.h"
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#include "base/StreamSerializing.h"
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#include "base/Lock.h"
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#include "base/Compiler.h"
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#include <algorithm>
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#include <cstdint>
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#include <unordered_map>
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// The purpose of StalePtrRegistry is to track integers corresponding to
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// host-side pointers that may be invalidated after snapshots.
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template <class T>
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class StalePtrRegistry {
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public:
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StalePtrRegistry() = default;
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void addPtr(T* ptr) {
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android::base::AutoWriteLock lock(mLock);
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mPtrs[asHandle(ptr)] = { ptr, Staleness::Live };
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}
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void removePtr(T* ptr) {
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android::base::AutoWriteLock lock(mLock);
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uint64_t handle = asHandle(ptr);
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mPtrs.erase(handle);
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}
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void remapStalePtr(uint64_t handle, T* newptr) {
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android::base::AutoWriteLock lock(mLock);
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mPtrs[handle] = { newptr, Staleness::PrevSnapshot };
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}
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T* getPtr(uint64_t handle, T* defaultPtr = nullptr,
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bool removeFromStaleOnGet = false) {
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android::base::AutoReadLock lock(mLock);
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// return |defaultPtr| if not found.
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T* res = defaultPtr;
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Entry* it = nullptr;
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if ((it = android::base::find(mPtrs, handle)))
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res = it->ptr;
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if (removeFromStaleOnGet &&
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it && it->staleness == Staleness::PrevSnapshot) {
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lock.unlockRead();
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android::base::AutoWriteLock wrlock(mLock);
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mPtrs.erase(handle);
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}
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return res;
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}
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void makeCurrentPtrsStale() {
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android::base::AutoWriteLock lock(mLock);
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for (auto& it : mPtrs) {
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it.second.staleness =
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Staleness::PrevSnapshot;
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}
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}
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size_t numCurrEntries() const {
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return countWithStaleness(Staleness::Live);
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}
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size_t numStaleEntries() const {
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return countWithStaleness(Staleness::PrevSnapshot);
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}
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void onSave(android::base::Stream* stream) {
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android::base::AutoReadLock lock(mLock);
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saveCollection(
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stream, mPtrs,
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[](android::base::Stream* stream,
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const std::pair<uint64_t, Entry>& entry) {
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stream->putBe64(entry.first);
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});
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}
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void onLoad(android::base::Stream* stream) {
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android::base::AutoWriteLock lock(mLock);
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loadCollection(
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stream, &mPtrs,
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[](android::base::Stream* stream) {
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uint64_t handle = stream->getBe64();
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return std::make_pair(
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handle,
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(Entry){ nullptr, Staleness::PrevSnapshot });
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});
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}
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private:
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static uint64_t asHandle(const T* ptr) {
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return (uint64_t)(uintptr_t)ptr;
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}
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static T* asPtr(uint64_t handle) {
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return (T*)(uintptr_t)handle;
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}
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enum class Staleness {
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Live,
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PrevSnapshot,
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};
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struct Entry {
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T* ptr;
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Staleness staleness;
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};
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using PtrMap = std::unordered_map<uint64_t, Entry>;
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size_t countWithStaleness(Staleness check) const {
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android::base::AutoReadLock lock(mLock);
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return std::count_if(mPtrs.begin(), mPtrs.end(),
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[check](const typename PtrMap::value_type& entry) {
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return entry.second.staleness == check;
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});
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}
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mutable android::base::ReadWriteLock mLock;
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PtrMap mPtrs;
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DISALLOW_COPY_AND_ASSIGN(StalePtrRegistry);
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};
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