innobase/include/sync0types.h

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*****************************************************************************/

/**************************************************//**
@file include/sync0types.h
Global types for sync

Created 9/5/1995 Heikki Tuuri
*******************************************************/

#ifndef sync0types_h
#define sync0types_h

#include <vector>
#include <iostream>

#include "ut0new.h"
#include "ut0counter.h"

#if defined(UNIV_DEBUG) && !defined(UNIV_INNOCHECKSUM)
/** Set when InnoDB has invoked exit(). */
extern bool	innodb_calling_exit;
#endif /* UNIV_DEBUG && !UNIV_INNOCHECKSUM */

#ifdef _WIN32
/** Native mutex */
typedef CRITICAL_SECTION	sys_mutex_t;
#else
/** Native mutex */
typedef pthread_mutex_t		sys_mutex_t;
#endif /* _WIN32 */

/** The new (C++11) syntax allows the following and we should use it when it
is available on platforms that we support.

	enum class mutex_state_t : lock_word_t { ... };
*/

/** Mutex states. */
enum mutex_state_t {
	/** Mutex is free */
	MUTEX_STATE_UNLOCKED = 0,

	/** Mutex is acquired by some thread. */
	MUTEX_STATE_LOCKED = 1,

	/** Mutex is contended and there are threads waiting on the lock. */
	MUTEX_STATE_WAITERS = 2
};

/*
		LATCHING ORDER WITHIN THE DATABASE
		==================================

The mutex or latch in the central memory object, for instance, a rollback
segment object, must be acquired before acquiring the latch or latches to
the corresponding file data structure. In the latching order below, these
file page object latches are placed immediately below the corresponding
central memory object latch or mutex.

Synchronization object			Notes
----------------------			-----

Dictionary mutex			If we have a pointer to a dictionary
|					object, e.g., a table, it can be
|					accessed without reserving the
|					dictionary mutex. We must have a
|					reservation, a memoryfix, to the
|					appropriate table object in this case,
|					and the table must be explicitly
|					released later.
V
Dictionary header
|
V
Secondary index tree latch		The tree latch protects also all
|					the B-tree non-leaf pages. These
V					can be read with the page only
Secondary index non-leaf		bufferfixed to save CPU time,
|					no s-latch is needed on the page.
|					Modification of a page requires an
|					x-latch on the page, however. If a
|					thread owns an x-latch to the tree,
|					it is allowed to latch non-leaf pages
|					even after it has acquired the fsp
|					latch.
V
Secondary index leaf			The latch on the secondary index leaf
|					can be kept while accessing the
|					clustered index, to save CPU time.
V
Clustered index tree latch		To increase concurrency, the tree
|					latch is usually released when the
|					leaf page latch has been acquired.
V
Clustered index non-leaf
|
V
Clustered index leaf
|
V
Transaction system header
|
V
Transaction undo mutex			The undo log entry must be written
|					before any index page is modified.
|					Transaction undo mutex is for the undo
|					logs the analogue of the tree latch
|					for a B-tree. If a thread has the
|					trx undo mutex reserved, it is allowed
|					to latch the undo log pages in any
|					order, and also after it has acquired
|					the fsp latch.
V
Rollback segment mutex			The rollback segment mutex must be
|					reserved, if, e.g., a new page must
|					be added to an undo log. The rollback
|					segment and the undo logs in its
|					history list can be seen as an
|					analogue of a B-tree, and the latches
|					reserved similarly, using a version of
|					lock-coupling. If an undo log must be
|					extended by a page when inserting an
|					undo log record, this corresponds to
|					a pessimistic insert in a B-tree.
V
Rollback segment header
|
V
Purge system latch
|
V
Undo log pages				If a thread owns the trx undo mutex,
|					or for a log in the history list, the
|					rseg mutex, it is allowed to latch
|					undo log pages in any order, and even
|					after it has acquired the fsp latch.
|					If a thread does not have the
|					appropriate mutex, it is allowed to
|					latch only a single undo log page in
|					a mini-transaction.
V
File space management latch		If a mini-transaction must allocate
|					several file pages, it can do that,
|					because it keeps the x-latch to the
|					file space management in its memo.
V
File system pages
|
V
lock_sys_wait_mutex			Mutex protecting lock timeout data
|
V
lock_sys_mutex				Mutex protecting lock_sys_t
|
V
trx_sys->mutex				Mutex protecting trx_sys_t
|
V
Threads mutex				Background thread scheduling mutex
|
V
query_thr_mutex				Mutex protecting query threads
|
V
trx_mutex				Mutex protecting trx_t fields
|
V
Search system mutex
|
V
Buffer pool mutexes
|
V
Log mutex
|
Any other latch
|
V
Memory pool mutex */

/** Latching order levels. If you modify these, you have to also update
LatchDebug internals in sync0debug.cc */

enum latch_level_t {
	SYNC_UNKNOWN = 0,

	SYNC_MUTEX = 1,

	RW_LOCK_SX,
	RW_LOCK_X_WAIT,
	RW_LOCK_S,
	RW_LOCK_X,
	RW_LOCK_NOT_LOCKED,

	SYNC_MONITOR_MUTEX,

	SYNC_ANY_LATCH,

	SYNC_DOUBLEWRITE,

	SYNC_BUF_FLUSH_LIST,
	SYNC_BUF_FLUSH_STATE,
	SYNC_BUF_ZIP_HASH,
	SYNC_BUF_FREE_LIST,
	SYNC_BUF_ZIP_FREE,
	SYNC_BUF_BLOCK,
	SYNC_BUF_PAGE_HASH,
	SYNC_BUF_LRU_LIST,
	SYNC_BUF_CHUNKS,

	SYNC_POOL,
	SYNC_POOL_MANAGER,

	SYNC_SEARCH_SYS,

	SYNC_WORK_QUEUE,

	SYNC_FTS_TOKENIZE,
	SYNC_FTS_OPTIMIZE,
	SYNC_FTS_BG_THREADS,
	SYNC_FTS_CACHE_INIT,
	SYNC_RECV,
	SYNC_LOG_FLUSH_ORDER,
	SYNC_LOG,
	SYNC_LOG_ONLINE,
	SYNC_LOG_WRITE,
	SYNC_PAGE_CLEANER,
	SYNC_PURGE_QUEUE,
	SYNC_TRX_SYS_HEADER,
	SYNC_REC_LOCK,
	SYNC_THREADS,
	SYNC_TRX,
	SYNC_TRX_SYS,
	SYNC_LOCK_SYS,
	SYNC_LOCK_WAIT_SYS,

	SYNC_INDEX_ONLINE_LOG,

	SYNC_IBUF_BITMAP,
	SYNC_IBUF_BITMAP_MUTEX,
	SYNC_IBUF_TREE_NODE,
	SYNC_IBUF_TREE_NODE_NEW,
	SYNC_IBUF_INDEX_TREE,

	SYNC_IBUF_MUTEX,

	SYNC_FSP_PAGE,
	SYNC_FSP,
	SYNC_EXTERN_STORAGE,
	SYNC_TRX_UNDO_PAGE,
	SYNC_RSEG_HEADER,
	SYNC_RSEG_HEADER_NEW,
	SYNC_NOREDO_RSEG,
	SYNC_REDO_RSEG,
	SYNC_TRX_UNDO,
	SYNC_PURGE_LATCH,
	SYNC_TREE_NODE,
	SYNC_TREE_NODE_FROM_HASH,
	SYNC_TREE_NODE_NEW,
	SYNC_INDEX_TREE,
	SYNC_ANALYZE_INDEX,

	SYNC_IBUF_PESS_INSERT_MUTEX,
	SYNC_IBUF_HEADER,
	SYNC_DICT_HEADER,
	SYNC_STATS_AUTO_RECALC,
	SYNC_DICT_AUTOINC_MUTEX,
	SYNC_DICT,
	SYNC_FTS_CACHE,

	SYNC_DICT_OPERATION,

	SYNC_FILE_FORMAT_TAG,

	SYNC_TRX_I_S_LAST_READ,

	SYNC_TRX_I_S_RWLOCK,

	/** Level is varying. Only used with buffer pool page locks, which
	do not have a fixed level, but instead have their level set after
	the page is locked; see e.g.  ibuf_bitmap_get_map_page(). */

	SYNC_LEVEL_VARYING,

	/** This can be used to suppress order checking. */
	SYNC_NO_ORDER_CHECK,

	/** Maximum level value */
	SYNC_LEVEL_MAX = SYNC_NO_ORDER_CHECK
};

/** Each latch has an ID. This id is used for creating the latch and to look
up its meta-data. See sync0debug.c. */
enum latch_id_t {
	LATCH_ID_NONE = 0,
	LATCH_ID_AUTOINC,
	LATCH_ID_BUF_BLOCK_MUTEX,
	LATCH_ID_BUF_POOL_CHUNKS,
	LATCH_ID_BUF_POOL_LRU_LIST,
	LATCH_ID_BUF_POOL_FREE_LIST,
	LATCH_ID_BUF_POOL_ZIP_FREE,
	LATCH_ID_BUF_POOL_ZIP_HASH,
	LATCH_ID_BUF_POOL_FLUSH_STATE,
	LATCH_ID_BUF_POOL_ZIP,
	LATCH_ID_CACHE_LAST_READ,
	LATCH_ID_DICT_FOREIGN_ERR,
	LATCH_ID_DICT_SYS,
	LATCH_ID_FILE_FORMAT_MAX,
	LATCH_ID_FIL_SYSTEM,
	LATCH_ID_FLUSH_LIST,
	LATCH_ID_FTS_BG_THREADS,
	LATCH_ID_FTS_DELETE,
	LATCH_ID_FTS_OPTIMIZE,
	LATCH_ID_FTS_DOC_ID,
	LATCH_ID_FTS_PLL_TOKENIZE,
	LATCH_ID_HASH_TABLE_MUTEX,
	LATCH_ID_IBUF_BITMAP,
	LATCH_ID_IBUF,
	LATCH_ID_IBUF_PESSIMISTIC_INSERT,
	LATCH_ID_LOG_SYS,
	LATCH_ID_LOG_ONLINE,
	LATCH_ID_LOG_WRITE,
	LATCH_ID_LOG_FLUSH_ORDER,
	LATCH_ID_LIST,
	LATCH_ID_MUTEX_LIST,
	LATCH_ID_PAGE_CLEANER,
	LATCH_ID_PURGE_SYS_PQ,
	LATCH_ID_RECALC_POOL,
	LATCH_ID_RECV_SYS,
	LATCH_ID_REDO_RSEG,
	LATCH_ID_NOREDO_RSEG,
	LATCH_ID_RW_LOCK_DEBUG,
	LATCH_ID_RTR_SSN_MUTEX,
	LATCH_ID_RTR_ACTIVE_MUTEX,
	LATCH_ID_RTR_MATCH_MUTEX,
	LATCH_ID_RTR_PATH_MUTEX,
	LATCH_ID_RW_LOCK_LIST,
	LATCH_ID_RW_LOCK_MUTEX,
	LATCH_ID_SRV_DICT_TMPFILE,
	LATCH_ID_SRV_INNODB_MONITOR,
	LATCH_ID_SRV_MISC_TMPFILE,
	LATCH_ID_SRV_MONITOR_FILE,
	LATCH_ID_SYNC_THREAD,
	LATCH_ID_BUF_DBLWR,
	LATCH_ID_TRX_UNDO,
	LATCH_ID_TRX_POOL,
	LATCH_ID_TRX_POOL_MANAGER,
	LATCH_ID_TRX,
	LATCH_ID_LOCK_SYS,
	LATCH_ID_LOCK_SYS_WAIT,
	LATCH_ID_TRX_SYS,
	LATCH_ID_SRV_SYS,
	LATCH_ID_SRV_SYS_TASKS,
	LATCH_ID_PAGE_ZIP_STAT_PER_INDEX,
	LATCH_ID_EVENT_MANAGER,
	LATCH_ID_EVENT_MUTEX,
	LATCH_ID_SYNC_ARRAY_MUTEX,
#ifdef _WIN32
	LATCH_ID_THREAD_MUTEX,
#endif
	LATCH_ID_ZIP_PAD_MUTEX,
	LATCH_ID_OS_AIO_READ_MUTEX,
	LATCH_ID_OS_AIO_WRITE_MUTEX,
	LATCH_ID_OS_AIO_LOG_MUTEX,
	LATCH_ID_OS_AIO_IBUF_MUTEX,
	LATCH_ID_OS_AIO_SYNC_MUTEX,
	LATCH_ID_ROW_DROP_LIST,
	LATCH_ID_INDEX_ONLINE_LOG,
	LATCH_ID_WORK_QUEUE,
	LATCH_ID_BTR_SEARCH,
	LATCH_ID_BUF_BLOCK_LOCK,
	LATCH_ID_BUF_BLOCK_DEBUG,
	LATCH_ID_DICT_OPERATION,
	LATCH_ID_CHECKPOINT,
	LATCH_ID_FIL_SPACE,
	LATCH_ID_FTS_CACHE,
	LATCH_ID_FTS_CACHE_INIT,
	LATCH_ID_TRX_I_S_CACHE,
	LATCH_ID_TRX_PURGE,
	LATCH_ID_IBUF_INDEX_TREE,
	LATCH_ID_INDEX_TREE,
	LATCH_ID_DICT_TABLE_STATS,
	LATCH_ID_HASH_TABLE_RW_LOCK,
	LATCH_ID_BUF_CHUNK_MAP_LATCH,
	LATCH_ID_SYNC_DEBUG_MUTEX,
	LATCH_ID_SCRUB_STAT_MUTEX,
	LATCH_ID_MASTER_KEY_ID_MUTEX,
	LATCH_ID_FIL_CRYPT_MUTEX,
	LATCH_ID_FIL_CRYPT_STAT_MUTEX,
	LATCH_ID_FIL_CRYPT_DATA_MUTEX,
	LATCH_ID_FIL_CRYPT_THREADS_MUTEX,
	LATCH_ID_FIL_CRYPT_START_ROTATE_MUTEX,
	LATCH_ID_ANALYZE_INDEX_MUTEX,
	LATCH_ID_TEST_MUTEX,
	LATCH_ID_MAX = LATCH_ID_TEST_MUTEX
};

#ifndef UNIV_INNOCHECKSUM
/** OS mutex, without any policy. It is a thin wrapper around the
system mutexes. The interface is different from the policy mutexes,
to ensure that it is called directly and not confused with the
policy mutexes. */
struct OSMutex {

	/** Constructor */
	OSMutex()
		UNIV_NOTHROW
	{
		ut_d(m_freed = true);
	}

	/** Create the mutex by calling the system functions. */
	void init()
		UNIV_NOTHROW
	{
		ut_ad(m_freed);

#ifdef _WIN32
		InitializeCriticalSection((LPCRITICAL_SECTION) &m_mutex);
#else
		{
			int	ret = pthread_mutex_init(&m_mutex, NULL);
			ut_a(ret == 0);
		}
#endif /* _WIN32 */

		ut_d(m_freed = false);
	}

	/** Destructor */
	~OSMutex() { }

	/** Destroy the mutex */
	void destroy()
		UNIV_NOTHROW
	{
		ut_ad(innodb_calling_exit || !m_freed);
#ifdef _WIN32
		DeleteCriticalSection((LPCRITICAL_SECTION) &m_mutex);
#else
		int	ret;

		ret = pthread_mutex_destroy(&m_mutex);

		if (ret != 0) {

			ib::error()
				<< "Return value " << ret << " when calling "
				<< "pthread_mutex_destroy().";
		}
#endif /* _WIN32 */
		ut_d(m_freed = true);
	}

	/** Release the mutex. */
	void exit()
		UNIV_NOTHROW
	{
		ut_ad(innodb_calling_exit || !m_freed);
#ifdef _WIN32
		LeaveCriticalSection(&m_mutex);
#else
		int	ret = pthread_mutex_unlock(&m_mutex);
		ut_a(ret == 0);
#endif /* _WIN32 */
	}

	/** Acquire the mutex. */
	void enter()
		UNIV_NOTHROW
	{
		ut_ad(innodb_calling_exit || !m_freed);
#ifdef _WIN32
		EnterCriticalSection((LPCRITICAL_SECTION) &m_mutex);
#else
		int	ret = pthread_mutex_lock(&m_mutex);
		ut_a(ret == 0);
#endif /* _WIN32 */
	}

	/** @return true if locking succeeded */
	bool try_lock()
		UNIV_NOTHROW
	{
		ut_ad(innodb_calling_exit || !m_freed);
#ifdef _WIN32
		return(TryEnterCriticalSection(&m_mutex) != 0);
#else
		return(pthread_mutex_trylock(&m_mutex) == 0);
#endif /* _WIN32 */
	}

	/** Required for os_event_t */
	operator sys_mutex_t*()
		UNIV_NOTHROW
	{
		return(&m_mutex);
	}

private:
#ifdef UNIV_DEBUG
	/** true if the mutex has been freed/destroyed. */
	bool			m_freed;
#endif /* UNIV_DEBUG */

	sys_mutex_t		m_mutex;
};

#ifdef UNIV_PFS_MUTEX
/** Latch element.
Used for mutexes which have PFS keys defined under UNIV_PFS_MUTEX.
@param[in]	id		Latch id
@param[in]	level		Latch level
@param[in]	key		PFS key */
# define LATCH_ADD_MUTEX(id, level, key)	latch_meta[LATCH_ID_ ## id] =\
	UT_NEW_NOKEY(latch_meta_t(LATCH_ID_ ## id, #id, level, #level, key))

#ifdef UNIV_PFS_RWLOCK
/** Latch element.
Used for rwlocks which have PFS keys defined under UNIV_PFS_RWLOCK.
@param[in]	id		Latch id
@param[in]	level		Latch level
@param[in]	key		PFS key */
# define LATCH_ADD_RWLOCK(id, level, key)	latch_meta[LATCH_ID_ ## id] =\
	UT_NEW_NOKEY(latch_meta_t(LATCH_ID_ ## id, #id, level, #level, key))
#else
# define LATCH_ADD_RWLOCK(id, level, key)	latch_meta[LATCH_ID_ ## id] =\
	UT_NEW_NOKEY(latch_meta_t(LATCH_ID_ ## id, #id, level, #level,	     \
		     PSI_NOT_INSTRUMENTED))
#endif /* UNIV_PFS_RWLOCK */

#else
# define LATCH_ADD_MUTEX(id, level, key)	latch_meta[LATCH_ID_ ## id] =\
	UT_NEW_NOKEY(latch_meta_t(LATCH_ID_ ## id, #id, level, #level))
# define LATCH_ADD_RWLOCK(id, level, key)	latch_meta[LATCH_ID_ ## id] =\
	UT_NEW_NOKEY(latch_meta_t(LATCH_ID_ ## id, #id, level, #level))
#endif /* UNIV_PFS_MUTEX */

/** Default latch counter */
class LatchCounter {

public:
	/** The counts we collect for a mutex */
	struct Count {

		/** Constructor */
		Count()
			UNIV_NOTHROW
			:
			m_spins(),
			m_waits(),
			m_calls(),
			m_enabled()
		{
			/* No op */
		}

		/** Rest the values to zero */
		void reset()
			UNIV_NOTHROW
		{
			m_spins = 0;
			m_waits = 0;
			m_calls = 0;
		}

		/** Number of spins trying to acquire the latch. */
		uint32_t	m_spins;

		/** Number of waits trying to acquire the latch */
		uint32_t	m_waits;

		/** Number of times it was called */
		uint32_t	m_calls;

		/** true if enabled */
		bool		m_enabled;
	};

	/** Constructor */
	LatchCounter()
		UNIV_NOTHROW
		:
		m_active(false)
	{
		m_mutex.init();
	}

	/** Destructor */
	~LatchCounter()
		UNIV_NOTHROW
	{
		m_mutex.destroy();

		for (Counters::iterator it = m_counters.begin();
		     it != m_counters.end();
		     ++it) {

			Count*	count = *it;

			UT_DELETE(count);
		}
	}

	/** Reset all counters to zero. It is not protected by any
	mutex and we don't care about atomicity. Unless it is a
	demonstrated problem. The information collected is not
	required for the correct functioning of the server. */
	void reset()
		UNIV_NOTHROW
	{
		m_mutex.enter();

		Counters::iterator	end = m_counters.end();

		for (Counters::iterator it = m_counters.begin();
		     it != end;
		     ++it) {

			(*it)->reset();
		}

		m_mutex.exit();
	}

	/** @return the aggregate counter */
	Count* sum_register()
		UNIV_NOTHROW
	{
		m_mutex.enter();

		Count*	count;

		if (m_counters.empty()) {
			count = UT_NEW_NOKEY(Count());
			m_counters.push_back(count);
		} else {
			ut_a(m_counters.size() == 1);
			count = m_counters[0];
		}

		m_mutex.exit();

		return(count);
	}

	/** Deregister the count. We don't do anything
	@param[in]	count		The count instance to deregister */
	void sum_deregister(Count* count)
		UNIV_NOTHROW
	{
		/* Do nothing */
	}

	/** Register a single instance counter */
	void single_register(Count* count)
		UNIV_NOTHROW
	{
		m_mutex.enter();

		m_counters.push_back(count);

		m_mutex.exit();
	}

	/** Deregister a single instance counter
	@param[in]	count		The count instance to deregister */
	void single_deregister(Count* count)
		UNIV_NOTHROW
	{
		m_mutex.enter();

		m_counters.erase(
			std::remove(
				m_counters.begin(),
				m_counters.end(), count),
			m_counters.end());

		m_mutex.exit();
	}

	/** Iterate over the counters */
	template <typename Callback>
	void iterate(Callback& callback) const
		UNIV_NOTHROW
	{
		m_mutex.enter();
		Counters::const_iterator	end = m_counters.end();

		for (Counters::const_iterator it = m_counters.begin();
		     it != end;
		     ++it) {

			callback(*it);
		}
		m_mutex.exit();
	}

	/** Disable the monitoring */
	void enable()
		UNIV_NOTHROW
	{
		m_mutex.enter();

		Counters::const_iterator	end = m_counters.end();

		for (Counters::const_iterator it = m_counters.begin();
		     it != end;
		     ++it) {

			(*it)->m_enabled = true;
		}

		m_active = true;

		m_mutex.exit();
	}

	/** Disable the monitoring */
	void disable()
		UNIV_NOTHROW
	{
		m_mutex.enter();

		Counters::const_iterator	end = m_counters.end();

		for (Counters::const_iterator it = m_counters.begin();
		     it != end;
		     ++it) {

			(*it)->m_enabled = false;
		}

		m_active = false;

		m_mutex.exit();
	}

	/** @return if monitoring is active */
	bool is_enabled() const
		UNIV_NOTHROW
	{
		return(m_active);
	}

private:
	/* Disable copying */
	LatchCounter(const LatchCounter&);
	LatchCounter& operator=(const LatchCounter&);

private:
	typedef OSMutex Mutex;
	typedef std::vector<Count*> Counters;

	/** Mutex protecting m_counters */
	mutable Mutex		m_mutex;

	/** Counters for the latches */
	Counters		m_counters;

	/** if true then we collect the data */
	bool			m_active;
};

/** Latch meta data */
template <typename Counter = LatchCounter>
class LatchMeta {

public:
	typedef Counter CounterType;

#ifdef UNIV_PFS_MUTEX
	typedef	mysql_pfs_key_t	pfs_key_t;
#endif /* UNIV_PFS_MUTEX */

	/** Constructor */
	LatchMeta()
		:
		m_id(LATCH_ID_NONE),
		m_name(),
		m_level(SYNC_UNKNOWN),
		m_level_name()
#ifdef UNIV_PFS_MUTEX
		,m_pfs_key()
#endif /* UNIV_PFS_MUTEX */
	{
	}

	/** Destructor */
	~LatchMeta() { }

	/** Constructor
	@param[in]	id		Latch id
	@param[in]	name		Latch name
	@param[in]	level		Latch level
	@param[in]	level_name	Latch level text representation
	@param[in]	key		PFS key */
	LatchMeta(
		latch_id_t	id,
		const char*	name,
		latch_level_t	level,
		const char*	level_name
#ifdef UNIV_PFS_MUTEX
		,pfs_key_t	key
#endif /* UNIV_PFS_MUTEX */
	      )
		:
		m_id(id),
		m_name(name),
		m_level(level),
		m_level_name(level_name)
#ifdef UNIV_PFS_MUTEX
		,m_pfs_key(key)
#endif /* UNIV_PFS_MUTEX */
	{
		/* No op */
	}

	/* Less than operator.
	@param[in]	rhs		Instance to compare against
	@return true if this.get_id() < rhs.get_id() */
	bool operator<(const LatchMeta& rhs) const
	{
		return(get_id() < rhs.get_id());
	}

	/** @return the latch id */
	latch_id_t get_id() const
	{
		return(m_id);
	}

	/** @return the latch name */
	const char* get_name() const
	{
		return(m_name);
	}

	/** @return the latch level */
	latch_level_t get_level() const
	{
		return(m_level);
	}

	/** @return the latch level name */
	const char* get_level_name() const
	{
		return(m_level_name);
	}

#ifdef UNIV_PFS_MUTEX
	/** @return the PFS key for the latch */
	pfs_key_t get_pfs_key() const
	{
		return(m_pfs_key);
	}
#endif /* UNIV_PFS_MUTEX */

	/** @return the counter instance */
	Counter* get_counter()
	{
		return(&m_counter);
	}

private:
	/** Latch id */
	latch_id_t		m_id;

	/** Latch name */
	const char*		m_name;

	/** Latch level in the ordering */
	latch_level_t		m_level;

	/** Latch level text representation */
	const char*		m_level_name;

#ifdef UNIV_PFS_MUTEX
	/** PFS key */
	pfs_key_t		m_pfs_key;
#endif /* UNIV_PFS_MUTEX */

	/** For gathering latch statistics */
	Counter			m_counter;
};

typedef LatchMeta<LatchCounter> latch_meta_t;
typedef std::vector<latch_meta_t*, ut_allocator<latch_meta_t*> > LatchMetaData;

/** Note: This is accessed without any mutex protection. It is initialised
at startup and elements should not be added to or removed from it after
that.  See sync_latch_meta_init() */
extern LatchMetaData	latch_meta;

/** Get the latch meta-data from the latch ID
@param[in]	id		Latch ID
@return the latch meta data */
inline
latch_meta_t&
sync_latch_get_meta(latch_id_t id)
{
	ut_ad(static_cast<size_t>(id) < latch_meta.size());
	ut_ad(id == latch_meta[id]->get_id());

	return(*latch_meta[id]);
}

/** Fetch the counter for the latch
@param[in]	id		Latch ID
@return the latch counter */
inline
latch_meta_t::CounterType*
sync_latch_get_counter(latch_id_t id)
{
	latch_meta_t&	meta = sync_latch_get_meta(id);

	return(meta.get_counter());
}

/** Get the latch name from the latch ID
@param[in]	id		Latch ID
@return the name, will assert if not found */
inline
const char*
sync_latch_get_name(latch_id_t id)
{
	const latch_meta_t&	meta = sync_latch_get_meta(id);

	return(meta.get_name());
}

/** Get the latch ordering level
@param[in]	id		Latch id to lookup
@return the latch level */
inline
latch_level_t
sync_latch_get_level(latch_id_t id)
{
	const latch_meta_t&	meta = sync_latch_get_meta(id);

	return(meta.get_level());
}

#ifdef UNIV_PFS_MUTEX
/** Get the latch PFS key from the latch ID
@param[in]	id		Latch ID
@return the PFS key */
inline
mysql_pfs_key_t
sync_latch_get_pfs_key(latch_id_t id)
{
	const latch_meta_t&	meta = sync_latch_get_meta(id);

	return(meta.get_pfs_key());
}
#endif

/** String representation of the filename and line number where the
latch was created
@param[in]	id		Latch ID
@param[in]	created		Filename and line number where it was crated
@return the string representation */
std::string
sync_mutex_to_string(
	latch_id_t		id,
	const std::string&	created);

/** Get the latch name from a sync level
@param[in]	level		Latch level to lookup
@return 0 if not found. */
const char*
sync_latch_get_name(latch_level_t level);

/** Print the filename "basename"
@return the basename */
const char*
sync_basename(const char* filename);

/** Register a latch, called when it is created
@param[in]	ptr		Latch instance that was created
@param[in]	filename	Filename where it was created
@param[in]	line		Line number in filename */
void
sync_file_created_register(
	const void*	ptr,
	const char*	filename,
	uint16_t	line);

/** Deregister a latch, called when it is destroyed
@param[in]	ptr		Latch to be destroyed */
void
sync_file_created_deregister(const void* ptr);

/** Get the string where the file was created. Its format is "name:line"
@param[in]	ptr		Latch instance
@return created information or "" if can't be found */
std::string
sync_file_created_get(const void* ptr);

#ifdef UNIV_DEBUG

/** All (ordered) latches, used in debugging, must derive from this class. */
struct latch_t {

	/** Constructor
	@param[in]	id	The latch ID */
	explicit latch_t(latch_id_t id = LATCH_ID_NONE)
		UNIV_NOTHROW
		:
		m_id(id),
		m_rw_lock(),
		m_temp_fsp() { }

	/** Destructor */
	virtual ~latch_t() UNIV_NOTHROW { }

	/** @return the latch ID */
	latch_id_t get_id() const
	{
		return(m_id);
	}

	/** @return true if it is a rw-lock */
	bool is_rw_lock() const
		UNIV_NOTHROW
	{
		return(m_rw_lock);
	}

	/** Print the latch context
	@return the string representation */
	virtual std::string to_string() const = 0;

	/** @return "filename:line" from where the latch was last locked */
	virtual std::string locked_from() const = 0;

	/** @return the latch level */
	latch_level_t get_level() const
		UNIV_NOTHROW
	{
		ut_a(m_id != LATCH_ID_NONE);

		return(sync_latch_get_level(m_id));
	}

	/** @return true if the latch is for a temporary file space*/
	bool is_temp_fsp() const
		UNIV_NOTHROW
	{
		return(m_temp_fsp);
	}

	/** Set the temporary tablespace flag. The latch order constraints
	are different for intrinsic tables. We don't always acquire the
	index->lock. We need to figure out the context and add some special
	rules during the checks. */
	void set_temp_fsp()
		UNIV_NOTHROW
	{
		ut_ad(get_id() == LATCH_ID_FIL_SPACE);
		m_temp_fsp = true;
	}

	/** @return the latch name, m_id must be set  */
	const char* get_name() const
		UNIV_NOTHROW
	{
		ut_a(m_id != LATCH_ID_NONE);

		return(sync_latch_get_name(m_id));
	}

	/** Latch ID */
	latch_id_t	m_id;

	/** true if it is a rw-lock. In debug mode, rw_lock_t derives from
	this class and sets this variable. */
	bool		m_rw_lock;

	/** true if it is an temporary space latch */
	bool		m_temp_fsp;
};

/** Subclass this to iterate over a thread's acquired latch levels. */
struct sync_check_functor_t {
	virtual ~sync_check_functor_t() { }
	virtual bool operator()(const latch_level_t) = 0;
	virtual bool result() const = 0;
};

/** Functor to check whether the calling thread owns the btr search mutex. */
struct btrsea_sync_check : public sync_check_functor_t {

	/** Constructor
	@param[in]	has_search_latch	true if owns the latch */
	explicit btrsea_sync_check(bool has_search_latch)
		:
		m_result(),
		m_has_search_latch(has_search_latch) { }

	/** Destructor */
	virtual ~btrsea_sync_check() { }

	/** Called for every latch owned by the calling thread.
	@param[in]	level		Level of the existing latch
	@return true if the predicate check is successful */
	virtual bool operator()(const latch_level_t level)
	{
		/* If calling thread doesn't hold search latch then
		check if there are latch level exception provided.

		Note: Optimizer has added InnoDB intrinsic table as an
		alternative to MyISAM intrinsic table. With this a new
		control flow comes into existence, it is:

		Server -> Plugin -> SE

		Plugin in this case is I_S which is sharing the latch vector
		of InnoDB and so there could be lock conflicts. Ideally
		the Plugin should use a difference namespace latch vector
		as it doesn't have any depedency with SE latching protocol.

		Added check that will allow thread to hold I_S latches */

		if (!m_has_search_latch
		    && (level != SYNC_SEARCH_SYS
			&& level != SYNC_FTS_CACHE
			&& level != SYNC_TRX_I_S_RWLOCK
			&& level != SYNC_TRX_I_S_LAST_READ)) {

			m_result = true;

			return(m_result);
		}

		return(false);
	}

	/** @return result from the check */
	virtual bool result() const
	{
		return(m_result);
	}

private:
	/** True if all OK */
	bool		m_result;

	/** If the caller owns the search latch */
	const bool	m_has_search_latch;
};

/** Functor to check for dictionay latching constraints. */
struct dict_sync_check : public sync_check_functor_t {

	/** Constructor
	@param[in]	dict_mutex_allow	true if the dict mutex
						is allowed */
	explicit dict_sync_check(bool dict_mutex_allowed)
		:
		m_result(),
		m_dict_mutex_allowed(dict_mutex_allowed) { }

	/** Destructor */
	virtual ~dict_sync_check() { }

	/** Check the latching constraints
	@param[in]	level		The level held by the thread */
	virtual bool operator()(const latch_level_t level)
	{
		if (!m_dict_mutex_allowed
		    || (level != SYNC_DICT
			&& level != SYNC_DICT_OPERATION
			&& level != SYNC_FTS_CACHE
			&& level != SYNC_NO_ORDER_CHECK)) {

			m_result = true;

			return(true);
		}

		return(false);
	}

	/** @return the result of the check */
	virtual bool result() const
	{
		return(m_result);
	}

private:
	/** True if all OK */
	bool		m_result;

	/** True if it is OK to hold the dict mutex */
	const bool	m_dict_mutex_allowed;
};

/** Functor to check for given latching constraints. */
struct sync_allowed_latches : public sync_check_functor_t {

	/** Constructor
	@param[in]	from	first element in an array of latch_level_t
	@param[in]	to	last element in an array of latch_level_t */
	sync_allowed_latches(
		const latch_level_t*	from,
		const latch_level_t*	to)
		:
		m_result(),
		m_latches(from, to) { }

	/** Checks whether the given latch_t violates the latch constraint.
	This object maintains a list of allowed latch levels, and if the given
	latch belongs to a latch level that is not there in the allowed list,
	then it is a violation.

	@param[in]	latch	The latch level to check
	@return true if there is a latch ordering violation */
	virtual bool operator()(const latch_level_t level)
	{
		for (latches_t::const_iterator it = m_latches.begin();
		     it != m_latches.end();
		     ++it) {

			if (level == *it) {

				m_result = false;

				/* No violation */
				return(false);
			}
		}

		return(true);
	}

	/** @return the result of the check */
	virtual bool result() const
	{
		return(m_result);
	}

private:
	/** Save the result of validation check here
	True if all OK */
	bool		m_result;

	typedef std::vector<latch_level_t, ut_allocator<latch_level_t> >
		latches_t;

	/** List of latch levels that are allowed to be held */
	latches_t	m_latches;
};

/** Get the latch id from a latch name.
@param[in]	id	Latch name
@return LATCH_ID_NONE. */
latch_id_t
sync_latch_get_id(const char* name);

typedef ulint rw_lock_flags_t;

/* Flags to specify lock types for rw_lock_own_flagged() */
enum rw_lock_flag_t {
	RW_LOCK_FLAG_S  = 1 << 0,
	RW_LOCK_FLAG_X  = 1 << 1,
	RW_LOCK_FLAG_SX = 1 << 2
};

#endif /* UNIV_DBEUG */

#endif /* UNIV_INNOCHECKSUM */

#endif /* sync0types_h */