~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_locks */

#ifndef DRIZZLED_THR_LOCK_H

#define DRIZZLED_THR_LOCK_H

#include <pthread.h>

namespace drizzled

{

struct st_thr_lock;

namespace internal

{

extern pthread_mutex_t THR_LOCK_lock;

}

extern uint64_t max_write_lock_count;

extern uint64_t table_lock_wait_timeout;

extern bool thr_lock_inited;

enum thr_lock_type { TL_IGNORE=-1,

                     /* UNLOCK ANY LOCK */

                     TL_UNLOCK,

                     /* Read lock */

                     TL_READ,

                     TL_READ_WITH_SHARED_LOCKS,

                     /* 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,

                     /*

                       parser only! Late bound low_priority flag.

                       At open_tables() becomes thd->update_lock_default.

                     */

                     TL_WRITE_DEFAULT,

                     /* 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 };

/*

  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;

  uint64_t 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 {

  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;

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_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 thr_abort_locks_for_thread(THR_LOCK *lock, uint64_t thread);

} /* namespace drizzled */

#endif /* DRIZZLED_THR_LOCK_H */