~drizzle-trunk/drizzle/development

/* Copyright (C) 2000 MySQL AB

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program; if not, write to the Free Software

   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/* For use with thr_lock:s */

#ifndef _thr_lock_h

#define _thr_lock_h

#ifdef	__cplusplus

extern "C" {

#endif

#include <mysys/my_pthread.h>

#include <mysys/my_list.h>

struct st_thr_lock;

extern uint32_t locks_immediate,locks_waited ;

extern pthread_mutex_t THR_LOCK_lock;

enum thr_lock_type { TL_IGNORE=-1,

		     TL_UNLOCK,			/* UNLOCK ANY LOCK */

		     TL_READ,			/* Read lock */

		     TL_READ_WITH_SHARED_LOCKS,

		     /* High prior. than TL_WRITE. Allow concurrent insert */

		     TL_READ_HIGH_PRIORITY,

		     /* READ, Don't allow concurrent insert */

		     TL_READ_NO_INSERT,

		     /* 

			Write lock, but allow other threads to read / write.

			Used by BDB tables in MySQL to mark that someone is

			reading/writing to the table.

		      */

		     TL_WRITE_ALLOW_WRITE,

		     /*

			Write lock, but allow other threads to read.

			Used by ALTER TABLE in MySQL to allow readers

			to use the table until ALTER TABLE is finished.

		     */

		     TL_WRITE_ALLOW_READ,

		     /*

		       WRITE lock used by concurrent insert. Will allow

		       READ, if one could use concurrent insert on table.

		     */

		     TL_WRITE_CONCURRENT_INSERT,

		     /* Write used by INSERT DELAYED.  Allows READ locks */

		     TL_WRITE_DELAYED,

                     /* 

                       parser only! Late bound low_priority flag. 

                       At open_tables() becomes thd->update_lock_default.

                     */

                     TL_WRITE_DEFAULT,

		     /* WRITE lock that has lower priority than TL_READ */

		     TL_WRITE_LOW_PRIORITY,

		     /* Normal WRITE lock */

		     TL_WRITE,

		     /* Abort new lock request with an error */

		     TL_WRITE_ONLY};

enum enum_thr_lock_result { THR_LOCK_SUCCESS= 0, THR_LOCK_ABORTED= 1,

                            THR_LOCK_WAIT_TIMEOUT= 2, THR_LOCK_DEADLOCK= 3 };

extern ulong max_write_lock_count;

extern ulong table_lock_wait_timeout;

extern bool thr_lock_inited;

extern enum thr_lock_type thr_upgraded_concurrent_insert_lock;

/*

  A description of the thread which owns the lock. The address

  of an instance of this structure is used to uniquely identify the thread.

*/

typedef struct st_thr_lock_info

{

  pthread_t thread;

  my_thread_id thread_id;

  uint32_t n_cursors;

} THR_LOCK_INFO;

/*

  Lock owner identifier. Globally identifies the lock owner within the

  thread and among all the threads. The address of an instance of this

  structure is used as id.

*/

typedef struct st_thr_lock_owner

{

  THR_LOCK_INFO *info;

} THR_LOCK_OWNER;

typedef struct st_thr_lock_data {

  THR_LOCK_OWNER *owner;

  struct st_thr_lock_data *next,**prev;

  struct st_thr_lock *lock;

  pthread_cond_t *cond;

  enum thr_lock_type type;

  void *status_param;			/* Param to status functions */

} THR_LOCK_DATA;

struct st_lock_list {

  THR_LOCK_DATA *data,**last;

};

typedef struct st_thr_lock {

  LIST list;

  pthread_mutex_t mutex;

  struct st_lock_list read_wait;

  struct st_lock_list read;

  struct st_lock_list write_wait;

  struct st_lock_list write;

  /* write_lock_count is incremented for write locks and reset on read locks */

  uint32_t write_lock_count;

  uint32_t read_no_write_count;

  void (*get_status)(void*, int);	/* When one gets a lock */

  void (*copy_status)(void*,void*);

  void (*update_status)(void*);		/* Before release of write */

  void (*restore_status)(void*);         /* Before release of read */

  bool (*check_status)(void *);

} THR_LOCK;

extern LIST *thr_lock_thread_list;

bool init_thr_lock(void);		/* Must be called once/thread */

#define thr_lock_owner_init(owner, info_arg) (owner)->info= (info_arg)

void thr_lock_info_init(THR_LOCK_INFO *info);

void thr_lock_init(THR_LOCK *lock);

void thr_lock_delete(THR_LOCK *lock);

void thr_lock_data_init(THR_LOCK *lock,THR_LOCK_DATA *data,

			void *status_param);

enum enum_thr_lock_result thr_lock(THR_LOCK_DATA *data,

                                   THR_LOCK_OWNER *owner,

                                   enum thr_lock_type lock_type);

void thr_unlock(THR_LOCK_DATA *data);

enum enum_thr_lock_result thr_multi_lock(THR_LOCK_DATA **data,

                                         uint32_t count, THR_LOCK_OWNER *owner);

void thr_multi_unlock(THR_LOCK_DATA **data,uint32_t count);

void thr_abort_locks(THR_LOCK *lock, bool upgrade_lock);

bool thr_abort_locks_for_thread(THR_LOCK *lock, my_thread_id thread);

bool thr_upgrade_write_delay_lock(THR_LOCK_DATA *data);

void    thr_downgrade_write_lock(THR_LOCK_DATA *data,

                                 enum thr_lock_type new_lock_type);

bool thr_reschedule_write_lock(THR_LOCK_DATA *data);

#ifdef	__cplusplus

}

#endif

#endif /* _thr_lock_h */