From: Simone Piccardi <piccardi@gnulinux.it>
Date: Thu, 9 Feb 2012 18:38:55 +0000 (+0000)
Subject: Esempio di come non fare una sleep. Da un vecchio suggerimento fatto
X-Git-Url: https://gapil.gnulinux.it/gitweb/?a=commitdiff_plain;h=7d039accae81b30524e7a01f0b3d24ae79ddbaf1;p=gapil.git

Esempio di come non fare una sleep. Da un vecchio suggerimento fatto
sulla mailing list del flug.
---

diff --git a/sources/sleep-me.c b/sources/sleep-me.c
new file mode 100644
index 0000000..4000826
--- /dev/null
+++ b/sources/sleep-me.c
@@ -0,0 +1,105 @@
+/* sleep-me.c
+ * 
+ * Copyright (C) 2012 Simone Piccardi
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+/*****************************************************************************
+ *
+ * File sleep-me.c: An example on how NOT to wait for a time...
+ * thanks to M.E. for suggesting it (for serious) some time ago in the
+ * FLUG (Firenze Linux User Group) mailing list
+ *
+ * Author: S. Piccardi Jan. 2012
+ *
+ *****************************************************************************/
+#include <sys/types.h>   /* primitive system data types */
+#include <sys/stat.h>    /* file characteristics constants and functions */
+#include <unistd.h>      /* unix standard library */
+#include <stdio.h>
+#include <time.h>
+#include <stdlib.h>
+
+/*
+ * Program sleep-me.c
+ *
+ * Wait for N second (burning CPU...)
+ */
+/* Help printing routine */
+void usage(void);
+/* computation function for dir_scan */
+int main(int argc, char *argv[]) 
+{
+    time_t now, end;
+    int i, wait=0;
+    /*
+     * Input section: decode command line parameters 
+     * Use getopt function
+     */
+    opterr = 0;	 /* don't want writing to stderr */
+    while ( (i = getopt(argc, argv, "h")) != -1) {
+	switch (i) {
+	/* 
+	 * Handling options 
+	 */ 
+	case 'h':                                            /* help option */
+	    printf("Wrong -h option use\n");
+	    usage();
+	    return -1;
+	    break;
+	case '?':                                    /* unrecognized options */
+	    printf("Unrecognized options -%c\n",optopt);
+	    usage();
+	default:                                       /* should not reached */
+	    usage();
+	}
+    }
+    /* ***********************************************************
+     * 
+     *		 Options processing completed
+     *
+     *		      Main code beginning
+     * 
+     * ***********************************************************/
+    if ((argc - optind) != 1) {          /* There must be remaing parameters */
+	printf("Wrong number of arguments %d\n", argc - optind);
+        usage();
+    }
+    printf("I will burn CPU for %s seconds\n", argv[1]);
+    wait = atoi(argv[1]);
+    printf("wait %d sec.\n", wait);
+    if (wait != 0) {
+	end = time(NULL)+ wait;
+    } else {
+	usage();
+    }
+    printf("now %d, end %d sec.\n",now, end);
+    now = time(NULL);
+    while (now < end) { 
+	now = time(NULL);
+    }
+    exit(0);
+}
+/*
+ * routine to print usage info and exit
+ */
+void usage(void) {
+    printf("Program sleep-me: wait burning CPU cicles \n");
+    printf("Usage:\n");
+    printf("  sleep-me [-h] -t sec \n");
+    printf("  -t sec	   wait sec seconds\n");
+    printf("  -h	   print this help\n");
+    exit(1);
+}