db2/db/db_thread.c

   1 /*-
   2  * See the file LICENSE for redistribution information.
   3  *
   4  * Copyright (c) 1996, 1997, 1998
   5  *      Sleepycat Software.  All rights reserved.
   6  */
   7
   8 #include "config.h"
   9
  10 #ifndef lint
  11 static const char sccsid[] = "@(#)db_thread.c   8.15 (Sleepycat) 4/26/98";
  12 #endif /* not lint */
  13
  14 #ifndef NO_SYSTEM_INCLUDES
  15 #include <sys/types.h>
  16
  17 #include <errno.h>
  18 #include <string.h>
  19 #endif
  20
  21 #include "db_int.h"
  22 #include "db_page.h"
  23 #include "db_am.h"
  24
  25 static int __db_getlockid __P((DB *, DB *));
  26
  27 /*
  28  * __db_gethandle --
  29  *      Called by db access method routines when the DB_THREAD flag is set.
  30  *      This routine returns a handle, either an existing handle from the
  31  *      chain of handles, or creating one if necessary.
  32  *
  33  * PUBLIC: int __db_gethandle __P((DB *, int (*)(DB *, DB *), DB **));
  34  */
  35 int
  36 __db_gethandle(dbp, am_func, dbpp)
  37         DB *dbp, **dbpp;
  38         int (*am_func) __P((DB *, DB *));
  39 {
  40         DB *ret_dbp;
  41         int ret, t_ret;
  42
  43         if ((ret = __db_mutex_lock((db_mutex_t *)dbp->mutexp, -1)) != 0)
  44                 return (ret);
  45
  46         if ((ret_dbp = LIST_FIRST(&dbp->handleq)) != NULL)
  47                 /* Simply take one off the list. */
  48                 LIST_REMOVE(ret_dbp, links);
  49         else {
  50                 /* Allocate a new handle. */
  51                 if ((ret_dbp = (DB *)__db_malloc(sizeof(*dbp))) == NULL) {
  52                         ret = ENOMEM;
  53                         goto err;
  54                 }
  55                 memcpy(ret_dbp, dbp, sizeof(*dbp));
  56                 ret_dbp->internal = NULL;
  57                 TAILQ_INIT(&ret_dbp->curs_queue);
  58
  59                 /* Set the locker, the lock structure and the lock DBT. */
  60                 if ((ret = __db_getlockid(dbp, ret_dbp)) != 0)
  61                         goto err;
  62
  63                 /* Finally, call the access method specific dup function. */
  64                 if ((ret = am_func(dbp, ret_dbp)) != 0)
  65                         goto err;
  66         }
  67
  68         *dbpp = ret_dbp;
  69
  70         if (0) {
  71 err:            if (ret_dbp != NULL)
  72                         FREE(ret_dbp, sizeof(*ret_dbp));
  73         }
  74         if ((t_ret =
  75             __db_mutex_unlock((db_mutex_t *)dbp->mutexp, -1)) != 0 && ret == 0)
  76                 ret = t_ret;
  77         return (ret);
  78 }
  79
  80 /*
  81  * __db_puthandle --
  82  *      Return a DB handle to the pool for later use.
  83  *
  84  * PUBLIC: int __db_puthandle __P((DB *));
  85  */
  86 int
  87 __db_puthandle(dbp)
  88         DB *dbp;
  89 {
  90         DB *master;
  91         int ret;
  92
  93         master = dbp->master;
  94         if ((ret = __db_mutex_lock((db_mutex_t *)master->mutexp, -1)) != 0)
  95                 return (ret);
  96
  97         LIST_INSERT_HEAD(&master->handleq, dbp, links);
  98
  99         return (__db_mutex_unlock((db_mutex_t *)master->mutexp, -1));
 100 }
 101
 102 /*
 103  * __db_getlockid --
 104  *      Create a new locker ID and copy the file lock information from
 105  *      the old DB into the new one.
 106  */
 107 static int
 108 __db_getlockid(dbp, new_dbp)
 109         DB *dbp, *new_dbp;
 110 {
 111         int ret;
 112
 113         if (F_ISSET(dbp, DB_AM_LOCKING)) {
 114                 if ((ret = lock_id(dbp->dbenv->lk_info, &new_dbp->locker)) != 0)
 115                         return (ret);
 116                 memcpy(new_dbp->lock.fileid, dbp->lock.fileid, DB_FILE_ID_LEN);
 117                 new_dbp->lock_dbt.size = sizeof(new_dbp->lock);
 118                 new_dbp->lock_dbt.data = &new_dbp->lock;
 119         }
 120         return (0);
 121 }