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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#pragma once
#ifndef ROCKSDB_LITE
#include <memory>
#include "rocksdb/rocksdb_namespace.h"
#include "rocksdb/status.h"
#include "rocksdb/types.h"
#include "rocksdb/utilities/transaction_db.h"
namespace ROCKSDB_NAMESPACE {
// Request for locking a single key.
struct PointLockRequest {
// The id of the key's column family.
ColumnFamilyId column_family_id = 0;
// The key to lock.
std::string key;
// The sequence number from which there is no concurrent update to key.
SequenceNumber seq = 0;
// Whether the lock is acquired only for read.
bool read_only = false;
// Whether the lock is in exclusive mode.
bool exclusive = true;
};
// Request for locking a range of keys.
struct RangeLockRequest {
// The id of the key's column family.
ColumnFamilyId column_family_id;
// The range to be locked
Endpoint start_endp;
Endpoint end_endp;
};
struct PointLockStatus {
// Whether the key is locked.
bool locked = false;
// Whether the key is locked in exclusive mode.
bool exclusive = true;
// The sequence number in the tracked PointLockRequest.
SequenceNumber seq = 0;
};
// Return status when calling LockTracker::Untrack.
enum class UntrackStatus {
// The lock is not tracked at all, so no lock to untrack.
NOT_TRACKED,
// The lock is untracked but not removed from the tracker.
UNTRACKED,
// The lock is removed from the tracker.
REMOVED,
};
// Tracks the lock requests.
// In PessimisticTransaction, it tracks the locks acquired through LockMgr;
// In OptimisticTransaction, since there is no LockMgr, it tracks the lock
// intention. Not thread-safe.
class LockTracker {
public:
virtual ~LockTracker() {}
// Whether supports locking a specific key.
virtual bool IsPointLockSupported() const = 0;
// Whether supports locking a range of keys.
virtual bool IsRangeLockSupported() const = 0;
// Tracks the acquirement of a lock on key.
//
// If this method is not supported, leave it as a no-op.
virtual void Track(const PointLockRequest& /*lock_request*/) = 0;
// Untracks the lock on a key.
// seq and exclusive in lock_request are not used.
//
// If this method is not supported, leave it as a no-op and
// returns NOT_TRACKED.
virtual UntrackStatus Untrack(const PointLockRequest& /*lock_request*/) = 0;
// Counterpart of Track(const PointLockRequest&) for RangeLockRequest.
virtual void Track(const RangeLockRequest& /*lock_request*/) = 0;
// Counterpart of Untrack(const PointLockRequest&) for RangeLockRequest.
virtual UntrackStatus Untrack(const RangeLockRequest& /*lock_request*/) = 0;
// Merges lock requests tracked in the specified tracker into the current
// tracker.
//
// E.g. for point lock, if a key in tracker is not yet tracked,
// track this new key; otherwise, merge the tracked information of the key
// such as lock's exclusiveness, read/write statistics.
//
// If this method is not supported, leave it as a no-op.
//
// REQUIRED: the specified tracker must be of the same concrete class type as
// the current tracker.
virtual void Merge(const LockTracker& /*tracker*/) = 0;
// This is a reverse operation of Merge.
//
// E.g. for point lock, if a key exists in both current and the sepcified
// tracker, then subtract the information (such as read/write statistics) of
// the key in the specified tracker from the current tracker.
//
// If this method is not supported, leave it as a no-op.
//
// REQUIRED:
// The specified tracker must be of the same concrete class type as
// the current tracker.
// The tracked locks in the specified tracker must be a subset of those
// tracked by the current tracker.
virtual void Subtract(const LockTracker& /*tracker*/) = 0;
// Clears all tracked locks.
virtual void Clear() = 0;
// Gets the new locks (excluding the locks that have been tracked before the
// save point) tracked since the specified save point, the result is stored
// in an internally constructed LockTracker and returned.
//
// save_point_tracker is the tracker used by a SavePoint to track locks
// tracked after creating the SavePoint.
//
// The implementation should document whether point lock, or range lock, or
// both are considered in this method.
// If this method is not supported, returns nullptr.
//
// REQUIRED:
// The save_point_tracker must be of the same concrete class type as the
// current tracker.
// The tracked locks in the specified tracker must be a subset of those
// tracked by the current tracker.
virtual LockTracker* GetTrackedLocksSinceSavePoint(
const LockTracker& /*save_point_tracker*/) const = 0;
// Gets lock related information of the key.
//
// If point lock is not supported, always returns LockStatus with
// locked=false.
virtual PointLockStatus GetPointLockStatus(
ColumnFamilyId /*column_family_id*/,
const std::string& /*key*/) const = 0;
// Gets number of tracked point locks.
//
// If point lock is not supported, always returns 0.
virtual uint64_t GetNumPointLocks() const = 0;
class ColumnFamilyIterator {
public:
virtual ~ColumnFamilyIterator() {}
// Whether there are remaining column families.
virtual bool HasNext() const = 0;
// Gets next column family id.
//
// If HasNext is false, calling this method has undefined behavior.
virtual ColumnFamilyId Next() = 0;
};
// Gets an iterator for column families.
//
// Returned iterator must not be nullptr.
// If there is no column family to iterate,
// returns an empty non-null iterator.
// Caller owns the returned pointer.
virtual ColumnFamilyIterator* GetColumnFamilyIterator() const = 0;
class KeyIterator {
public:
virtual ~KeyIterator() {}
// Whether there are remaining keys.
virtual bool HasNext() const = 0;
// Gets the next key.
//
// If HasNext is false, calling this method has undefined behavior.
virtual const std::string& Next() = 0;
};
// Gets an iterator for keys with tracked point locks in the column family.
//
// The column family must exist.
// Returned iterator must not be nullptr.
// Caller owns the returned pointer.
virtual KeyIterator* GetKeyIterator(
ColumnFamilyId /*column_family_id*/) const = 0;
};
// LockTracker should always be constructed through this factory.
// Each LockManager owns a LockTrackerFactory.
class LockTrackerFactory {
public:
// Caller owns the returned pointer.
virtual LockTracker* Create() const = 0;
virtual ~LockTrackerFactory() {}
};
} // namespace ROCKSDB_NAMESPACE
#endif // ROCKSDB_LITE
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