db2/db/db_thread.c

   1 /*-
   2  * See the file LICENSE for redistribution information.
   3  *
   4  * Copyright (c) 1996, 1997
   5  *      Sleepycat Software.  All rights reserved.
   6  */
   7
   8 #include "config.h"
   9
  10 #ifndef lint
  11 static const char sccsid[] = "@(#)db_thread.c   8.13 (Sleepycat) 10/25/97";
  12 #endif /* not lint */
  13
  14 #ifndef NO_SYSTEM_INCLUDES
  15 #include <sys/types.h>
  16
  17 #include <errno.h>
  18 #include <stdlib.h>
  19 #include <string.h>
  20 #endif
  21
  22 #include "db_int.h"
  23 #include "db_page.h"
  24 #include "shqueue.h"
  25 #include "db_am.h"
  26
  27 static int __db_getlockid __P((DB *, DB *));
  28
  29 /*
  30  * __db_gethandle --
  31  *      Called by db access method routines when the DB_THREAD flag is set.
  32  *      This routine returns a handle, either an existing handle from the
  33  *      chain of handles, or creating one if necessary.
  34  *
  35  * PUBLIC: int __db_gethandle __P((DB *, int (*)(DB *, DB *), DB **));
  36  */
  37 int
  38 __db_gethandle(dbp, am_func, dbpp)
  39         DB *dbp, **dbpp;
  40         int (*am_func) __P((DB *, DB *));
  41 {
  42         DB *ret_dbp;
  43         int ret, t_ret;
  44
  45         if ((ret = __db_mutex_lock((db_mutex_t *)dbp->mutexp, -1)) != 0)
  46                 return (ret);
  47
  48         if ((ret_dbp = LIST_FIRST(&dbp->handleq)) != NULL)
  49                 /* Simply take one off the list. */
  50                 LIST_REMOVE(ret_dbp, links);
  51         else {
  52                 /* Allocate a new handle. */
  53                 if ((ret_dbp = (DB *)__db_malloc(sizeof(*dbp))) == NULL) {
  54                         ret = ENOMEM;
  55                         goto err;
  56                 }
  57                 memcpy(ret_dbp, dbp, sizeof(*dbp));
  58                 ret_dbp->internal = NULL;
  59                 TAILQ_INIT(&ret_dbp->curs_queue);
  60
  61                 /* Set the locker, the lock structure and the lock DBT. */
  62                 if ((ret = __db_getlockid(dbp, ret_dbp)) != 0)
  63                         goto err;
  64
  65                 /* Finally, call the access method specific dup function. */
  66                 if ((ret = am_func(dbp, ret_dbp)) != 0)
  67                         goto err;
  68         }
  69
  70         *dbpp = ret_dbp;
  71
  72         if (0) {
  73 err:            if (ret_dbp != NULL)
  74                         FREE(ret_dbp, sizeof(*ret_dbp));
  75         }
  76         if ((t_ret =
  77             __db_mutex_unlock((db_mutex_t *)dbp->mutexp, -1)) != 0 && ret == 0)
  78                 ret = t_ret;
  79         return (ret);
  80 }
  81
  82 /*
  83  * __db_puthandle --
  84  *      Return a DB handle to the pool for later use.
  85  *
  86  * PUBLIC: int __db_puthandle __P((DB *));
  87  */
  88 int
  89 __db_puthandle(dbp)
  90         DB *dbp;
  91 {
  92         DB *master;
  93         int ret;
  94
  95         master = dbp->master;
  96         if ((ret = __db_mutex_lock((db_mutex_t *)master->mutexp, -1)) != 0)
  97                 return (ret);
  98
  99         LIST_INSERT_HEAD(&master->handleq, dbp, links);
 100
 101         return (__db_mutex_unlock((db_mutex_t *)master->mutexp, -1));
 102 }
 103
 104 /*
 105  * __db_getlockid --
 106  *      Create a new locker ID and copy the file lock information from
 107  *      the old DB into the new one.
 108  */
 109 static int
 110 __db_getlockid(dbp, new_dbp)
 111         DB *dbp, *new_dbp;
 112 {
 113         int ret;
 114
 115         if (F_ISSET(dbp, DB_AM_LOCKING)) {
 116                 if ((ret = lock_id(dbp->dbenv->lk_info, &new_dbp->locker)) != 0)
 117                         return (ret);
 118                 memcpy(new_dbp->lock.fileid, dbp->lock.fileid, DB_FILE_ID_LEN);
 119                 new_dbp->lock_dbt.size = sizeof(new_dbp->lock);
 120                 new_dbp->lock_dbt.data = &new_dbp->lock;
 121         }
 122         return (0);
 123 }