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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#ifndef mozilla_dom_localstorage_LSWriteOptimizer_h
#define mozilla_dom_localstorage_LSWriteOptimizer_h
#include <cstdint>
#include <utility>
#include "mozilla/Assertions.h"
#include "mozilla/CheckedInt.h"
#include "mozilla/UniquePtr.h"
#include "nsClassHashtable.h"
#include "nsHashKeys.h"
#include "nsISupports.h"
#include "nsStringFwd.h"
#include "nsTArrayForwardDeclare.h"
namespace mozilla::dom {
/**
* Base class for coalescing manipulation queue.
*/
class LSWriteOptimizerBase {
class WriteInfoComparator;
protected:
class WriteInfo;
class DeleteItemInfo;
class TruncateInfo;
UniquePtr<WriteInfo> mTruncateInfo;
nsClassHashtable<nsStringHashKey, WriteInfo> mWriteInfos;
CheckedUint64 mLastSerialNumber;
int64_t mTotalDelta;
NS_DECL_OWNINGTHREAD
public:
LSWriteOptimizerBase() : mLastSerialNumber(0), mTotalDelta(0) {}
LSWriteOptimizerBase(LSWriteOptimizerBase&& aWriteOptimizer)
: mTruncateInfo(std::move(aWriteOptimizer.mTruncateInfo)) {
AssertIsOnOwningThread();
MOZ_ASSERT(&aWriteOptimizer != this);
mWriteInfos.SwapElements(aWriteOptimizer.mWriteInfos);
mTotalDelta = aWriteOptimizer.mTotalDelta;
aWriteOptimizer.mTotalDelta = 0;
}
void AssertIsOnOwningThread() const {
NS_ASSERT_OWNINGTHREAD(LSWriteOptimizerBase);
}
void DeleteItem(const nsAString& aKey, int64_t aDelta = 0);
void Truncate(int64_t aDelta = 0);
bool HasWrites() const {
AssertIsOnOwningThread();
return mTruncateInfo || !mWriteInfos.IsEmpty();
}
void Reset() {
AssertIsOnOwningThread();
mTruncateInfo = nullptr;
mWriteInfos.Clear();
}
protected:
uint64_t NextSerialNumber() {
AssertIsOnOwningThread();
mLastSerialNumber++;
MOZ_ASSERT(mLastSerialNumber.isValid());
return mLastSerialNumber.value();
}
/**
* This method can be used by derived classes to get a sorted list of write
* infos. Write infos are sorted by the serial number.
*/
void GetSortedWriteInfos(nsTArray<NotNull<WriteInfo*>>& aWriteInfos);
};
/**
* Base class for specific mutations.
*/
class LSWriteOptimizerBase::WriteInfo {
uint64_t mSerialNumber;
public:
WriteInfo(uint64_t aSerialNumber) : mSerialNumber(aSerialNumber) {}
virtual ~WriteInfo() = default;
uint64_t SerialNumber() const { return mSerialNumber; }
enum Type { InsertItem = 0, UpdateItem, DeleteItem, Truncate };
virtual Type GetType() const = 0;
};
class LSWriteOptimizerBase::DeleteItemInfo final : public WriteInfo {
nsString mKey;
public:
DeleteItemInfo(uint64_t aSerialNumber, const nsAString& aKey)
: WriteInfo(aSerialNumber), mKey(aKey) {}
const nsAString& GetKey() const { return mKey; }
private:
Type GetType() const override { return DeleteItem; }
};
/**
* Truncate mutation.
*/
class LSWriteOptimizerBase::TruncateInfo final : public WriteInfo {
public:
explicit TruncateInfo(uint64_t aSerialNumber) : WriteInfo(aSerialNumber) {}
private:
Type GetType() const override { return Truncate; }
};
/**
* Coalescing manipulation queue.
*/
template <typename T, typename U = T>
class LSWriteOptimizer;
template <typename T, typename U>
class LSWriteOptimizer : public LSWriteOptimizerBase {
protected:
class InsertItemInfo;
class UpdateItemInfo;
public:
void InsertItem(const nsAString& aKey, const T& aValue, int64_t aDelta = 0);
void UpdateItem(const nsAString& aKey, const T& aValue, int64_t aDelta = 0);
};
/**
* Insert mutation (the key did not previously exist).
*/
template <typename T, typename U>
class LSWriteOptimizer<T, U>::InsertItemInfo : public WriteInfo {
nsString mKey;
U mValue;
public:
InsertItemInfo(uint64_t aSerialNumber, const nsAString& aKey, const T& aValue)
: WriteInfo(aSerialNumber), mKey(aKey), mValue(aValue) {}
const nsAString& GetKey() const { return mKey; }
const T& GetValue() const { return mValue; }
private:
WriteInfo::Type GetType() const override { return InsertItem; }
};
/**
* Update mutation (the key already existed).
*/
template <typename T, typename U>
class LSWriteOptimizer<T, U>::UpdateItemInfo final : public InsertItemInfo {
bool mUpdateWithMove;
public:
UpdateItemInfo(uint64_t aSerialNumber, const nsAString& aKey, const T& aValue,
bool aUpdateWithMove)
: InsertItemInfo(aSerialNumber, aKey, aValue),
mUpdateWithMove(aUpdateWithMove) {}
bool UpdateWithMove() const { return mUpdateWithMove; }
private:
WriteInfo::Type GetType() const override { return WriteInfo::UpdateItem; }
};
} // namespace mozilla::dom
#endif // mozilla_dom_localstorage_LSWriteOptimizer_h