Cliff Woolley wrote: >On Sun, 9 Sep 2001, Brian Pane wrote: > >>I think putting it in APR would work. The one limitation I can think of >>is that adding the cache in apr_explode_localtime() itself wouldn't be a >>win because we'd have to add the overhead of a gettimeofday() call to >>check whether the supplied time was indeed current (and thus susceptible >>to caching). >> > >It took me a minute to figure out why this was a problem, but you're >right. I don't really like the idea of combining time_now and >explode_localtime, though. What about some kind of deal like >apr_explode_recent_localtime() which is the same as >apr_explode_localtime() except that the input must never be older than >TIME_CACHE_SIZE seconds? Or is that too httpd-tailored? If so, no sweat, >make it an ap_ function instead of an apr_ function. > I think it's relatively httpd-specific, so I used ap_explode_recent_localtime(). Here's the revised patch, plus the new files include/util_time.h and server/util_time.c --Brian Index: modules/loggers/mod_log_config.c =================================================================== RCS file: /home/cvspublic/httpd-2.0/modules/loggers/mod_log_config.c,v retrieving revision 1.68 diff -u -r1.68 mod_log_config.c --- modules/loggers/mod_log_config.c 2001/08/27 20:50:01 1.68 +++ modules/loggers/mod_log_config.c 2001/09/10 06:42:02 @@ -463,9 +463,9 @@ a problem with this, you can set the define. -djg */ #ifdef I_INSIST_ON_EXTRA_CYCLES_FOR_CLF_COMPLIANCE - apr_explode_localtime(&xt, apr_time_now()); + ap_explode_recent_localtime(&xt, apr_time_now()); #else - apr_explode_localtime(&xt, r->request_time); + ap_explode_recent_localtime(&xt, r->request_time); #endif if (a && *a) { /* Custom format */ apr_strftime(tstr, &retcode, MAX_STRING_LEN, a, &xt);
/* ==================================================================== * The Apache Software License, Version 1.1 * * Copyright (c) 2001 The Apache Software Foundation. All rights * reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. The end-user documentation included with the redistribution, * if any, must include the following acknowledgment: * "This product includes software developed by the * Apache Software Foundation (http://www.apache.org/)." * Alternately, this acknowledgment may appear in the software itself, * if and wherever such third-party acknowledgments normally appear. * * 4. The names "Apache" and "Apache Software Foundation" must * not be used to endorse or promote products derived from this * software without prior written permission. For written * permission, please contact [EMAIL PROTECTED] * * 5. Products derived from this software may not be called "Apache", * nor may "Apache" appear in their name, without prior written * permission of the Apache Software Foundation. * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * ==================================================================== * * This software consists of voluntary contributions made by many * individuals on behalf of the Apache Software Foundation. For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. * * Portions of this software are based upon public domain software * originally written at the National Center for Supercomputing Applications, * University of Illinois, Urbana-Champaign. */ #ifndef APACHE_UTIL_TIME_H #define APACHE_UTIL_TIME_H #include "apr.h" #include "apr_time.h" #include "httpd.h" #ifdef __cplusplus extern "C" { #endif /** * @package Apache date/time handling functions */ /* Maximum delta from the current time, in seconds, for a past time * to qualify as "recent" for use in the ap_explode_recent_*() functions: */ #define AP_TIME_RECENT_THRESHOLD 15 /** * convert a recent time to its human readable components in local timezone * @param tm the exploded time * @param t the time to explode: MUST be within the last * AP_TIME_RECENT_THRESHOLD seconds * @note This is a faster alternative to apr_explode_localtime that uses * a cache of pre-exploded time structures. It is useful for things * that need to explode the current time multiple times per second, * like loggers. * @return APR_SUCCESS iff successful * @deffunc apr_status_t ap_explode_recent_localtime(apr_exploded_time_t *tm, apr_time_t t); */ AP_DECLARE(apr_status_t) ap_explode_recent_localtime(apr_exploded_time_t *tm, apr_time_t t); /** * convert a recent time to its human readable components in GMT timezone * @param tm the exploded time * @param t the time to explode: MUST be within the last * AP_TIME_RECENT_THRESHOLD seconds * @note This is a faster alternative to apr_explode_gmt that uses * a cache of pre-exploded time structures. It is useful for things * that need to explode the current time multiple times per second, * like loggers. * @return APR_SUCCESS iff successful * @deffunc apr_status_t ap_explode_recent_gmt(apr_exploded_time_t *tm, apr_time_t t); */ AP_DECLARE(apr_status_t) ap_explode_recent_gmt(apr_exploded_time_t *tm, apr_time_t t); #ifdef __cplusplus } #endif #endif /* !APACHE_UTIL_TIME_H */
/* ==================================================================== * The Apache Software License, Version 1.1 * * Copyright (c) 2001 The Apache Software Foundation. All rights * reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. The end-user documentation included with the redistribution, * if any, must include the following acknowledgment: * "This product includes software developed by the * Apache Software Foundation (http://www.apache.org/)." * Alternately, this acknowledgment may appear in the software itself, * if and wherever such third-party acknowledgments normally appear. * * 4. The names "Apache" and "Apache Software Foundation" must * not be used to endorse or promote products derived from this * software without prior written permission. For written * permission, please contact [EMAIL PROTECTED] * * 5. Products derived from this software may not be called "Apache", * nor may "Apache" appear in their name, without prior written * permission of the Apache Software Foundation. * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * ==================================================================== * * This software consists of voluntary contributions made by many * individuals on behalf of the Apache Software Foundation. For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. * * Portions of this software are based upon public domain software * originally written at the National Center for Supercomputing Applications, * University of Illinois, Urbana-Champaign. */ #include "util_time.h" /* Cache for exploded values of recent timestamps */ struct exploded_time_cache_element { apr_int64_t t; apr_exploded_time_t xt; }; /* the "+ 1" is for the current second: */ #define TIME_CACHE_SIZE (AP_TIME_RECENT_THRESHOLD + 1) static struct exploded_time_cache_element exploded_cache_localtime[TIME_CACHE_SIZE]; static struct exploded_time_cache_element exploded_cache_gmt[TIME_CACHE_SIZE]; static apr_status_t cached_explode(apr_exploded_time_t *xt, apr_time_t t, struct exploded_time_cache_element *cache) { apr_int64_t seconds = t / APR_USEC_PER_SEC; struct exploded_time_cache_element *cache_element = &(cache[seconds % TIME_CACHE_SIZE]); /* The cache is implemented as a ring buffer. Each second, * it uses a different element in the buffer. The timestamp * in the element indicates whether the element contains the * exploded time for the current second (vs the time * 'now - AP_TIME_RECENT_THRESHOLD' seconds ago). If the * cached value is for the current time, we use it. Otherwise, * we compute the apr_exploded_time_t and store it in this * cache element. Note that the timestamp in the cache * element is updated only after the exploded time. Thus * if two threads hit this cache element simultaneously * at the start of a new second, they'll both explode the * time and store it. I.e., the writers will collide, but * they'll be writing the same value. */ if (cache_element->t >= seconds) { /* Note: If this memcpy ever takes more than TIME_CACHE_SIZE * seconds, the value will be unpredictable (because this * bucket in the ring buffer will have been recycled). This * memcpy should never take multiple seconds, but TIME_CACHE_SIZE * has a relatively large value just in case. */ memcpy(xt, &(cache_element->xt), sizeof(apr_exploded_time_t)); } else { apr_status_t r = apr_explode_localtime(xt, t); if (!APR_STATUS_IS_SUCCESS(r)) { return r; } memcpy(&(cache_element->xt), xt, sizeof(apr_exploded_time_t)); cache_element->t = seconds; } xt->tm_usec = t % APR_USEC_PER_SEC; return APR_SUCCESS; } AP_DECLARE(apr_status_t) ap_explode_recent_localtime(apr_exploded_time_t * tm, apr_time_t t) { return cached_explode(tm, t, exploded_cache_localtime); } AP_DECLARE(apr_status_t) ap_explode_recent_gmt(apr_exploded_time_t * tm, apr_time_t t) { return cached_explode(tm, t, exploded_cache_gmt); }