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#pragma once
#include <Common/TransactionID.h>
#include <Interpreters/StorageID.h>
namespace Poco
{
class Logger;
}
namespace DB
{
/// This structure allows to pass more information about a part that transaction is trying to create/remove.
/// It's useful for logging and for exception messages.
struct TransactionInfoContext
{
/// To which table a part belongs
StorageID table = StorageID::createEmpty();
/// Name of a part that transaction is trying to create/remove
String part_name;
/// Optional: name of part that covers `part_name` if transaction is trying to remove `part_name`
String covering_part;
TransactionInfoContext(StorageID id, String part) : table(std::move(id)), part_name(std::move(part)) {}
};
/// This structure contains metadata of an object (currently it's used for data parts in MergeTree only)
/// that allows to determine when and by which transaction it has been created/removed
struct VersionMetadata
{
/// ID of transaction that has created/is trying to create this object
TransactionID creation_tid = Tx::EmptyTID;
/// ID of transaction that has removed/is trying to remove this object
TransactionID removal_tid = Tx::EmptyTID;
/// Hash of removal_tid, used to lock an object for removal
std::atomic<TIDHash> removal_tid_lock = 0;
/// CSN of transaction that has created this object
std::atomic<CSN> creation_csn = Tx::UnknownCSN;
/// CSN of transaction that has removed this object
std::atomic<CSN> removal_csn = Tx::UnknownCSN;
/// Checks if an object is visible for transaction or not.
bool isVisible(const MergeTreeTransaction & txn);
bool isVisible(CSN snapshot_version, TransactionID current_tid = Tx::EmptyTID);
TransactionID getCreationTID() const { return creation_tid; }
TransactionID getRemovalTID() const;
/// Looks an object for removal, throws if it's already locked by concurrent transaction
bool tryLockRemovalTID(const TransactionID & tid, const TransactionInfoContext & context, TIDHash * locked_by_id = nullptr);
void lockRemovalTID(const TransactionID & tid, const TransactionInfoContext & context);
/// Unlocks an object for removal (when transaction is rolling back)
void unlockRemovalTID(const TransactionID & tid, const TransactionInfoContext & context);
bool isRemovalTIDLocked() const;
/// It can be called only from MergeTreeTransaction or on server startup
void setCreationTID(const TransactionID & tid, TransactionInfoContext * context);
/// Checks if it's safe to remove outdated version of an object
bool canBeRemoved();
bool canBeRemovedImpl(CSN oldest_snapshot_version);
void write(WriteBuffer & buf) const;
void read(ReadBuffer & buf);
enum WhichCSN { CREATION, REMOVAL };
void writeCSN(WriteBuffer & buf, WhichCSN which_csn, bool internal = false) const;
void writeRemovalTID(WriteBuffer & buf, bool clear = false) const;
String toString(bool one_line = true) const;
Poco::Logger * log;
VersionMetadata();
};
DataTypePtr getTransactionIDDataType();
}
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