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[exim.git] / src / src / enq.c

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+/* $Cambridge: exim/src/src/enq.c,v 1.1 2004/10/07 10:39:01 ph10 Exp $ */
+
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2004 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* Functions concerned with serialization. */
+
+
+#include "exim.h"
+
+
+
+
+/*************************************************
+*       Test for host or ETRN serialization      *
+*************************************************/
+
+/* This function is called when a host is listed for serialization of
+connections. It is also called when ETRN is listed for serialization. We open
+the misc database and look for a record, which implies an existing connection
+or ETRN run. If not found, create one and return TRUE.
+
+Arguments:
+  key            string on which to serialize
+
+Returns:         TRUE if OK to proceed; FALSE otherwise
+*/
+
+
+BOOL
+enq_start(uschar *key)
+{
+dbdata_serialize *serial_record;
+dbdata_serialize new_record;
+open_db dbblock;
+open_db *dbm_file;
+
+DEBUG(D_transport) debug_printf("check serialized: %s\n", key);
+
+/* Open and lock the waiting information database. The absence of O_CREAT is
+deliberate; the dbfn_open() function - which is an Exim function - always tries
+to create if it can't open a read/write file. It expects only O_RDWR or
+O_RDONLY as its argument. */
+
+dbm_file = dbfn_open(US"misc", O_RDWR, &dbblock, TRUE);
+if (dbm_file == NULL) return FALSE;
+
+/* See if there is a record for this host or queue run; if there is, we cannot
+proceed with the connection unless the record is very old. */
+
+serial_record = dbfn_read(dbm_file, key);
+if (serial_record != NULL && time(NULL) - serial_record->time_stamp < 6*60*60)
+  {
+  dbfn_close(dbm_file);
+  DEBUG(D_transport) debug_printf("outstanding serialization record for %s\n",
+    key);
+  return FALSE;
+  }
+
+/* We can proceed - insert a new record or update the old one. At present
+the count field is not used; just set it to 1. */
+
+new_record.count = 1;
+dbfn_write(dbm_file, key, &new_record, (int)sizeof(dbdata_serialize));
+dbfn_close(dbm_file);
+return TRUE;
+}
+
+
+
+/*************************************************
+*              Release serialization             *
+*************************************************/
+
+/* This function is called when a serialized host's connection or serialized
+ETRN queue run ends. We open the relevant database and delete its record.
+
+Arguments:
+  key          the serialization key
+
+Returns:       nothing
+*/
+
+void
+enq_end(uschar *key)
+{
+open_db dbblock;
+open_db *dbm_file;
+
+DEBUG(D_transport) debug_printf("end serialized: %s\n", key);
+
+dbm_file = dbfn_open(US"misc", O_RDWR, &dbblock, TRUE);
+if (dbm_file == NULL) return;
+dbfn_delete(dbm_file, key);
+dbfn_close(dbm_file);
+}
+
+/* End of enq.c */