170 lines
4.4 KiB
C
170 lines
4.4 KiB
C
/*
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* Copyright (c) 2015
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* The President and Fellows of Harvard College.
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* Written by David A. Holland.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <unistd.h>
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#include <fcntl.h>
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#include <err.h>
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#include <errno.h>
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#include <assert.h>
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#include "results.h"
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#define RESULTSFILE "endtimes"
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static int resultsfile = -1;
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/*
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* Create the file that the timing results are written to.
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* This is done first, in the main process.
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*/
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void
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createresultsfile(void)
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{
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int fd;
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assert(resultsfile == -1);
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fd = open(RESULTSFILE, O_RDWR|O_CREAT|O_TRUNC, 0664);
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if (fd < 0) {
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err(1, "%s", RESULTSFILE);
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}
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if (close(fd) == -1) {
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warn("%s: close", RESULTSFILE);
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}
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}
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/*
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* Remove the timing results file.
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* This is done last, in the main process.
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*/
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void
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destroyresultsfile(void)
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{
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if (remove(RESULTSFILE) == -1) {
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if (errno != ENOSYS) {
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warn("%s: remove", RESULTSFILE);
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}
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}
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}
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/*
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* Open the timing results file. This is done separately for writing
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* in each process to avoid sharing the seek position (which would
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* then require extra semaphoring to coordinate...) and afterwards
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* done for reading in the main process.
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*/
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void
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openresultsfile(int openflags)
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{
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assert(openflags == O_RDONLY || openflags == O_WRONLY);
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assert(resultsfile == -1);
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resultsfile = open(RESULTSFILE, openflags, 0);
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if (resultsfile < 0) {
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err(1, "%s", RESULTSFILE);
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}
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}
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/*
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* Close the timing results file.
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*/
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void
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closeresultsfile(void)
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{
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assert(resultsfile >= 0);
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if (close(resultsfile) == -1) {
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warn("%s: close", RESULTSFILE);
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}
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resultsfile = -1;
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}
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/*
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* Write a result into the timing results file.
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*/
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void
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putresult(unsigned groupid, time_t secs, unsigned long nsecs)
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{
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off_t pos;
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ssize_t r;
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assert(resultsfile >= 0);
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pos = groupid * (sizeof(secs) + sizeof(nsecs));
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if (lseek(resultsfile, pos, SEEK_SET) == -1) {
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err(1, "%s: lseek", RESULTSFILE);
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}
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r = write(resultsfile, &secs, sizeof(secs));
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if (r < 0) {
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err(1, "%s: write (seconds)", RESULTSFILE);
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}
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if ((size_t)r < sizeof(secs)) {
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errx(1, "%s: write (seconds): Short write", RESULTSFILE);
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}
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r = write(resultsfile, &nsecs, sizeof(nsecs));
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if (r < 0) {
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err(1, "%s: write (nsecs)", RESULTSFILE);
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}
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if ((size_t)r < sizeof(nsecs)) {
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errx(1, "%s: write (nsecs): Short write", RESULTSFILE);
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}
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}
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/*
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* Read a result from the timing results file.
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*/
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void
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getresult(unsigned groupid, time_t *secs, unsigned long *nsecs)
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{
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off_t pos;
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ssize_t r;
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assert(resultsfile >= 0);
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pos = groupid * (sizeof(*secs) + sizeof(*nsecs));
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if (lseek(resultsfile, pos, SEEK_SET) == -1) {
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err(1, "%s: lseek", RESULTSFILE);
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}
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r = read(resultsfile, secs, sizeof(*secs));
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if (r < 0) {
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err(1, "%s: read (seconds)", RESULTSFILE);
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}
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if ((size_t)r < sizeof(*secs)) {
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errx(1, "%s: read (seconds): Unexpected EOF", RESULTSFILE);
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}
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r = read(resultsfile, nsecs, sizeof(*nsecs));
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if (r < 0) {
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err(1, "%s: read (nsecs)", RESULTSFILE);
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}
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if ((size_t)r < sizeof(*nsecs)) {
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errx(1, "%s: read (nsecs): Unexpected EOF", RESULTSFILE);
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}
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}
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