1/* trans.c - bdb backend transaction routines */ 2/* $OpenLDAP$ */ 3/* This work is part of OpenLDAP Software <http://www.openldap.org/>. 4 * 5 * Copyright 2000-2011 The OpenLDAP Foundation. 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted only as authorized by the OpenLDAP 10 * Public License. 11 * 12 * A copy of this license is available in the file LICENSE in the 13 * top-level directory of the distribution or, alternatively, at 14 * <http://www.OpenLDAP.org/license.html>. 15 */ 16 17#include "portable.h" 18 19#include <stdio.h> 20#include <ac/string.h> 21 22#include "back-bdb.h" 23#include "lber_pvt.h" 24#include "lutil.h" 25 26 27/* Congestion avoidance code 28 * for Deadlock Rollback 29 */ 30 31void 32bdb_trans_backoff( int num_retries ) 33{ 34 int i; 35 int delay = 0; 36 int pow_retries = 1; 37 unsigned long key = 0; 38 unsigned long max_key = -1; 39 struct timeval timeout; 40 41 lutil_entropy( (unsigned char *) &key, sizeof( unsigned long )); 42 43 for ( i = 0; i < num_retries; i++ ) { 44 if ( i >= 5 ) break; 45 pow_retries *= 4; 46 } 47 48 delay = 16384 * (key * (double) pow_retries / (double) max_key); 49 delay = delay ? delay : 1; 50 51 Debug( LDAP_DEBUG_TRACE, "delay = %d, num_retries = %d\n", delay, num_retries, 0 ); 52 53 timeout.tv_sec = delay / 1000000; 54 timeout.tv_usec = delay % 1000000; 55 select( 0, NULL, NULL, NULL, &timeout ); 56} 57