/usr/include/dnsdb/zdb-zone-lock.h is in libyadifa-dev 2.2.3-1+deb9u1.
This file is owned by root:root, with mode 0o644.
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*
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/** @defgroup dnsdbzone Zone related functions
* @ingroup dnsdb
* @brief Functions used to manipulate a zone
*
* Functions used to manipulate a zone
*
* @{
*/
#pragma once
#include <dnsdb/zdb_types.h>
#ifdef __cplusplus
extern "C"
{
#endif
/**
* Zone locking
*
* Sets the owner of a zone.
*
* The owner id has a format: the msb is reserved to say that the access is
* exclusive to only one instance of the owner.
* The remaining bits are the id.
*
* Mostly used for the simple reader and various writers.
*
* A new feature needs to be added: being able to pre-lock for an owner.
*
* Explanation: I want to lock for the signing process. But that process
* is done in two or three phases. The first phase is read-only (thus allowing
* the server to work normally). But I don't want sombody else, say, a dynamic
* update, to lock the zone in the mean time. (Which would happen when the lock
* is transferred from the reader to the signer (at the commit phase).
* So I'll add a secondary owner, meant to tell "I lock as a reader BUT I also
* reserve the right for myself later". And later a transfer can be done to
* the secondary as soon as the last reader unlocks.
*
* zdb_zone_double_lock(zone, owner, secondary owner)
* zdb_zone_try_double_lock(zone, owner, secondary owner)
* zdb_zone_transfer_lock(zone, secondary owner)
*
* The parameter would need to be repeated to detect inconsistencies (bugs)
*
* This should have no effect on the normal locking mechanism, thus ensuring
* no loss of speed. The only goal is to avoid a race changing the owner.
*
* Having only zdb_zone_transfer_lock(zone, old owner, new owner) cannot work
* because nothing prevents two soon-to-be writers to lock and work in tandem.
*
*/
void zdb_zone_lock(zdb_zone *zone, u8 owner);
bool zdb_zone_trylock(zdb_zone *zone, u8 owner);
void zdb_zone_unlock(zdb_zone *zone, u8 owner);
bool zdb_zone_islocked(zdb_zone *zone);
/**
* Returns TRUE iff the zone is locked by a writer (any other owner value than nobody and simple reader)
*
* @param zone
* @return
*/
bool zdb_zone_iswritelocked(zdb_zone *zone);
/**
* Reserves the secondary owner and to locks for the owner
*
* @param zone
* @param owner
* @param secondary_owner
*/
void zdb_zone_double_lock(zdb_zone *zone, u8 owner, u8 secondary_owner);
/**
* Tries to reserve the secondary owner and to lock for the owner
*
* @param zone
* @param owner
* @param secondary_owner
*/
bool zdb_zone_try_double_lock(zdb_zone *zone, u8 owner, u8 secondary_owner);
/**
*
* Unlocks one owner and sets the secondary owner to nobody
*
* @param zone
* @param owner
* @param secondary_owner
*/
void zdb_zone_double_unlock(zdb_zone *zone, u8 owner, u8 secondary_owner);
/**
*
* Puts the secondary lock in place of the lock when the locker count reaches 1
* Followed by a zdb_zone_unlock
*
* @param zone
* @param owner
* @param secondary_owner
*/
void zdb_zone_transfer_lock(zdb_zone *zone, u8 owner, u8 secondary_owner);
/**
*
* Puts the secondary lock in place of the lock when the locker count reaches 1
* Followed by a zdb_zone_unlock
*
* @param zone
* @param owner
* @param secondary_owner
*/
bool zdb_zone_try_transfer_lock(zdb_zone *zone, u8 owner, u8 secondary_owner);
/**
*
* Exchange the primary and secondary locks when the locker count reaches 1
* Followed by a zdb_zone_unlock
*
* @param zone
* @param owner
* @param secondary_owner
*/
void zdb_zone_exchange_locks(zdb_zone *zone, u8 owner, u8 secondary_owner);
#if DNSCORE_HAS_MUTEX_DEBUG_SUPPORT
void zdb_zone_lock_set_monitor();
#endif
/** @} */
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