~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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA */

/* For use with thr_locks */

#pragma once

#include <boost/thread/mutex.hpp>

#include <boost/thread/shared_mutex.hpp>

#include <boost/thread/condition_variable.hpp>

#include <drizzled/visibility.h>

#include <drizzled/common_fwd.h>

namespace drizzled {

extern uint64_t max_write_lock_count;

extern uint64_t table_lock_wait_timeout;

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.

*/

struct THR_LOCK_INFO

{

  uint64_t thread_id;

  uint32_t n_cursors;

  THR_LOCK_INFO() : 

    thread_id(0),

    n_cursors(0)

  { }

  void init();

};

/*

  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.

*/

struct THR_LOCK_OWNER

{

  THR_LOCK_INFO *info;

  THR_LOCK_OWNER() :

    info(NULL)

  { }

};

struct THR_LOCK;

struct THR_LOCK_DATA;

struct DRIZZLED_API THR_LOCK_DATA 

{

  THR_LOCK_OWNER *owner;

  struct THR_LOCK_DATA *next,**prev;

  struct THR_LOCK *lock;

  boost::condition_variable_any *cond;

  enum thr_lock_type type;

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

  THR_LOCK_DATA() :

    owner(0),

    next(0),

    prev(0),

    lock(0),

    cond(0),

    type(TL_UNLOCK),

    status_param(0)

  { }

  void init(THR_LOCK*, void *status_param= NULL);

};

struct st_lock_list 

{

  THR_LOCK_DATA *data,**last;

  st_lock_list() :

    data(0),

    last(0)

  { }

};

struct THR_LOCK 

{

private:

  boost::mutex mutex;

public:

  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;

  THR_LOCK() :

    write_lock_count(0),

    read_no_write_count(0)

  { }

  void abort_locks();

  bool abort_locks_for_thread(uint64_t thread);

  void lock()

  {

    mutex.lock();

  }

  void unlock()

  {

    mutex.unlock();

  }

  boost::mutex *native_handle()

  {

    return &mutex;

  }

};

DRIZZLED_API void thr_lock_init(THR_LOCK *lock);

enum_thr_lock_result thr_multi_lock(Session&, THR_LOCK_DATA**, uint32_t count, THR_LOCK_OWNER*);

void thr_multi_unlock(THR_LOCK_DATA**, uint32_t count);

} /* namespace drizzled */