src/src/enq.c

   1 /*************************************************
   2 *     Exim - an Internet mail transport agent    *
   3 *************************************************/
   4
   5 /* Copyright (c) University of Cambridge 1995 - 2009 */
   6 /* See the file NOTICE for conditions of use and distribution. */
   7
   8 /* Functions concerned with serialization. */
   9
  10
  11 #include "exim.h"
  12
  13
  14
  15
  16 /*************************************************
  17 *       Test for host or ETRN serialization      *
  18 *************************************************/
  19
  20 /* This function is called when a host is listed for serialization of
  21 connections. It is also called when ETRN is listed for serialization. We open
  22 the misc database and look for a record, which implies an existing connection
  23 or ETRN run. If not found, create one and return TRUE.
  24
  25 Arguments:
  26   key            string on which to serialize
  27
  28 Returns:         TRUE if OK to proceed; FALSE otherwise
  29 */
  30
  31
  32 BOOL
  33 enq_start(uschar *key)
  34 {
  35 dbdata_serialize *serial_record;
  36 dbdata_serialize new_record;
  37 open_db dbblock;
  38 open_db *dbm_file;
  39
  40 DEBUG(D_transport) debug_printf("check serialized: %s\n", key);
  41
  42 /* Open and lock the waiting information database. The absence of O_CREAT is
  43 deliberate; the dbfn_open() function - which is an Exim function - always tries
  44 to create if it can't open a read/write file. It expects only O_RDWR or
  45 O_RDONLY as its argument. */
  46
  47 dbm_file = dbfn_open(US"misc", O_RDWR, &dbblock, TRUE);
  48 if (dbm_file == NULL) return FALSE;
  49
  50 /* See if there is a record for this host or queue run; if there is, we cannot
  51 proceed with the connection unless the record is very old. */
  52
  53 serial_record = dbfn_read(dbm_file, key);
  54 if (serial_record != NULL && time(NULL) - serial_record->time_stamp < 6*60*60)
  55   {
  56   dbfn_close(dbm_file);
  57   DEBUG(D_transport) debug_printf("outstanding serialization record for %s\n",
  58     key);
  59   return FALSE;
  60   }
  61
  62 /* We can proceed - insert a new record or update the old one. At present
  63 the count field is not used; just set it to 1. */
  64
  65 new_record.count = 1;
  66 dbfn_write(dbm_file, key, &new_record, (int)sizeof(dbdata_serialize));
  67 dbfn_close(dbm_file);
  68 return TRUE;
  69 }
  70
  71
  72
  73 /*************************************************
  74 *              Release serialization             *
  75 *************************************************/
  76
  77 /* This function is called when a serialized host's connection or serialized
  78 ETRN queue run ends. We open the relevant database and delete its record.
  79
  80 Arguments:
  81   key          the serialization key
  82
  83 Returns:       nothing
  84 */
  85
  86 void
  87 enq_end(uschar *key)
  88 {
  89 open_db dbblock;
  90 open_db *dbm_file;
  91
  92 DEBUG(D_transport) debug_printf("end serialized: %s\n", key);
  93
  94 dbm_file = dbfn_open(US"misc", O_RDWR, &dbblock, TRUE);
  95 if (dbm_file == NULL) return;
  96 dbfn_delete(dbm_file, key);
  97 dbfn_close(dbm_file);
  98 }
  99
 100 /* End of enq.c */