src/src/enq.c

   1 /* $Cambridge: exim/src/src/enq.c,v 1.2 2005/01/04 10:00:42 ph10 Exp $ */
   2
   3 /*************************************************
   4 *     Exim - an Internet mail transport agent    *
   5 *************************************************/
   6
   7 /* Copyright (c) University of Cambridge 1995 - 2005 */
   8 /* See the file NOTICE for conditions of use and distribution. */
   9
  10 /* Functions concerned with serialization. */
  11
  12
  13 #include "exim.h"
  14
  15
  16
  17
  18 /*************************************************
  19 *       Test for host or ETRN serialization      *
  20 *************************************************/
  21
  22 /* This function is called when a host is listed for serialization of
  23 connections. It is also called when ETRN is listed for serialization. We open
  24 the misc database and look for a record, which implies an existing connection
  25 or ETRN run. If not found, create one and return TRUE.
  26
  27 Arguments:
  28   key            string on which to serialize
  29
  30 Returns:         TRUE if OK to proceed; FALSE otherwise
  31 */
  32
  33
  34 BOOL
  35 enq_start(uschar *key)
  36 {
  37 dbdata_serialize *serial_record;
  38 dbdata_serialize new_record;
  39 open_db dbblock;
  40 open_db *dbm_file;
  41
  42 DEBUG(D_transport) debug_printf("check serialized: %s\n", key);
  43
  44 /* Open and lock the waiting information database. The absence of O_CREAT is
  45 deliberate; the dbfn_open() function - which is an Exim function - always tries
  46 to create if it can't open a read/write file. It expects only O_RDWR or
  47 O_RDONLY as its argument. */
  48
  49 dbm_file = dbfn_open(US"misc", O_RDWR, &dbblock, TRUE);
  50 if (dbm_file == NULL) return FALSE;
  51
  52 /* See if there is a record for this host or queue run; if there is, we cannot
  53 proceed with the connection unless the record is very old. */
  54
  55 serial_record = dbfn_read(dbm_file, key);
  56 if (serial_record != NULL && time(NULL) - serial_record->time_stamp < 6*60*60)
  57   {
  58   dbfn_close(dbm_file);
  59   DEBUG(D_transport) debug_printf("outstanding serialization record for %s\n",
  60     key);
  61   return FALSE;
  62   }
  63
  64 /* We can proceed - insert a new record or update the old one. At present
  65 the count field is not used; just set it to 1. */
  66
  67 new_record.count = 1;
  68 dbfn_write(dbm_file, key, &new_record, (int)sizeof(dbdata_serialize));
  69 dbfn_close(dbm_file);
  70 return TRUE;
  71 }
  72
  73
  74
  75 /*************************************************
  76 *              Release serialization             *
  77 *************************************************/
  78
  79 /* This function is called when a serialized host's connection or serialized
  80 ETRN queue run ends. We open the relevant database and delete its record.
  81
  82 Arguments:
  83   key          the serialization key
  84
  85 Returns:       nothing
  86 */
  87
  88 void
  89 enq_end(uschar *key)
  90 {
  91 open_db dbblock;
  92 open_db *dbm_file;
  93
  94 DEBUG(D_transport) debug_printf("end serialized: %s\n", key);
  95
  96 dbm_file = dbfn_open(US"misc", O_RDWR, &dbblock, TRUE);
  97 if (dbm_file == NULL) return;
  98 dbfn_delete(dbm_file, key);
  99 dbfn_close(dbm_file);
 100 }
 101
 102 /* End of enq.c */