time: new module for dealing with time.

ccan/time/LICENSE

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+../../licenses/BSD-MIT

ccan/time/_info

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+#include <string.h>
+#include "config.h"
+
+/**
+ * time - routines for dealing with time
+ *
+ * This code provides convenient functions for working with time.
+ *
+ * Author: Rusty Russell <rusty@rustcorp.com.au>
+ * License: BSD-MIT
+ *
+ * Example:
+ *	#include <ccan/time/time.h>
+ *	#include <stdlib.h>
+ *	#include <stdio.h>
+ *	#include <err.h>
+ *
+ *	int main(int argc, char *argv[])
+ *	{
+ *		struct timeval t;
+ *
+ *		if (argc != 2)
+ *			errx(1, "Usage: %s <diff in millisec>", argv[0]);
+ *
+ *		t = time_now();
+ *		if (argv[1][0] == '-')
+ *			t = time_sub(t, time_from_msec(atol(argv[1]+1)));
+ *		else
+ *			t = time_add(t, time_from_msec(atol(argv[1])));
+ *
+ *		printf("%lu.%06u\n",
+ *		       (unsigned long)t.tv_sec, (unsigned)t.tv_usec);
+ *		return 0;
+ *	}
+ */
+int main(int argc, char *argv[])
+{
+	/* Expect exactly one argument */
+	if (argc != 2)
+		return 1;
+
+	if (strcmp(argv[1], "depends") == 0) {
+		return 0;
+	}
+
+	return 1;
+}

ccan/time/test/run.c

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+#include <ccan/time/time.h>
+#include <ccan/time/time.c>
+#include <ccan/tap/tap.h>
+
+int main(void)
+{
+	struct timeval t1, t2, t3, zero = { 0, 0 };
+
+	plan_tests(46);
+
+	/* Test time_now */
+	t1 = time_now();
+	t2 = time_now();
+
+	/* Test time_sub. */
+	t3 = time_sub(t2, t1);
+	ok1(t3.tv_sec > 0 || t3.tv_usec >= 0);
+	t3 = time_sub(t2, t2);
+	ok1(t3.tv_sec == 0 && t3.tv_usec == 0);
+	t3 = time_sub(t1, t1);
+	ok1(t3.tv_sec == 0 && t3.tv_usec == 0);
+
+	/* Test time_eq */
+	ok1(time_eq(t1, t1));
+	ok1(time_eq(t2, t2));
+	ok1(!time_eq(t1, t3));
+	ok1(!time_eq(t2, t3));
+
+	/* Make sure t2 > t1. */
+	t3.tv_sec = 0;
+	t3.tv_usec = 1;
+	t2 = time_add(t2, t3);
+
+	/* Test time_less and time_greater. */
+	ok1(!time_eq(t1, t2));
+	ok1(!time_greater(t1, t2));
+	ok1(time_less(t1, t2));
+	ok1(time_greater(t2, t1));
+	ok1(!time_less(t2, t1));
+	t3.tv_sec = 0;
+	t3.tv_usec = 999999;
+	t2 = time_add(t2, t3);
+	ok1(!time_eq(t1, t2));
+	ok1(!time_greater(t1, t2));
+	ok1(time_less(t1, t2));
+	ok1(time_greater(t2, t1));
+	ok1(!time_less(t2, t1));
+
+	t3 = time_sub(t2, zero);
+	ok1(time_eq(t3, t2));
+	t3 = time_sub(t2, t2);
+	ok1(time_eq(t3, zero));
+
+	/* time_from_msec / time_to_msec */
+	t3 = time_from_msec(500);
+	ok1(t3.tv_sec == 0);
+	ok1(t3.tv_usec == 500000);
+	ok1(time_to_msec(t3) == 500);
+
+	t3 = time_from_msec(1000);
+	ok1(t3.tv_sec == 1);
+	ok1(t3.tv_usec == 0);
+	ok1(time_to_msec(t3) == 1000);
+
+	t3 = time_from_msec(1500);
+	ok1(t3.tv_sec == 1);
+	ok1(t3.tv_usec == 500000);
+	ok1(time_to_msec(t3) == 1500);
+
+	/* time_from_usec */
+	t3 = time_from_usec(500000);
+	ok1(t3.tv_sec == 0);
+	ok1(t3.tv_usec == 500000);
+	ok1(time_to_usec(t3) == 500000);
+
+	t3 = time_from_usec(1000000);
+	ok1(t3.tv_sec == 1);
+	ok1(t3.tv_usec == 0);
+	ok1(time_to_usec(t3) == 1000000);
+
+	t3 = time_from_usec(1500000);
+	ok1(t3.tv_sec == 1);
+	ok1(t3.tv_usec == 500000);
+	ok1(time_to_usec(t3) == 1500000);
+
+	/* Test wrapunder */
+	t3 = time_sub(time_sub(t2, time_from_msec(500)), time_from_msec(500));
+	ok1(t3.tv_sec == t2.tv_sec - 1);
+	ok1(t3.tv_usec == t2.tv_usec);
+
+	/* time_divide and time_multiply */
+	t1.tv_usec = 100;
+	t1.tv_sec = 100;
+
+	t3 = time_divide(t1, 2);
+	ok1(t3.tv_sec == 50);
+	ok1(t3.tv_usec == 50);
+
+	t3 = time_divide(t1, 100);
+	ok1(t3.tv_sec == 1);
+	ok1(t3.tv_usec == 1);
+
+	t3 = time_multiply(t3, 100);
+	ok1(time_eq(t3, t1));
+
+	t3 = time_divide(t1, 200);
+	ok1(t3.tv_sec == 0);
+	ok1(t3.tv_usec == 500000);
+
+	return exit_status();
+}

ccan/time/time.c

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+#include <ccan/time/time.h>
+#include <stdlib.h>
+#include <assert.h>
+
+struct timeval time_now(void)
+{
+	struct timeval now;
+	gettimeofday(&now, NULL);
+	return now;
+}
+
+bool time_greater(struct timeval a, struct timeval b)
+{
+	if (a.tv_sec > b.tv_sec)
+		return true;
+	else if (a.tv_sec < b.tv_sec)
+		 return false;
+
+	return a.tv_usec > b.tv_usec;
+}
+
+bool time_less(struct timeval a, struct timeval b)
+{
+	if (a.tv_sec < b.tv_sec)
+		return true;
+	else if (a.tv_sec > b.tv_sec)
+		 return false;
+
+	return a.tv_usec < b.tv_usec;
+}
+
+bool time_eq(struct timeval a, struct timeval b)
+{
+	return a.tv_sec == b.tv_sec && a.tv_usec == b.tv_usec;
+}
+
+struct timeval time_sub(struct timeval recent, struct timeval old)
+{
+	struct timeval diff;
+
+	diff.tv_sec = recent.tv_sec - old.tv_sec;
+	if (old.tv_usec > recent.tv_usec) {
+		diff.tv_sec--;
+		diff.tv_usec = 1000000 + recent.tv_usec - old.tv_usec;
+	} else
+		diff.tv_usec = recent.tv_usec - old.tv_usec;
+
+	assert(diff.tv_sec >= 0);
+	return diff;
+}
+
+struct timeval time_add(struct timeval a, struct timeval b)
+{
+	struct timeval sum;
+
+	sum.tv_sec = a.tv_sec + b.tv_sec;
+	sum.tv_usec = a.tv_usec + b.tv_usec;
+	if (sum.tv_usec > 1000000) {
+		sum.tv_sec++;
+		sum.tv_usec -= 1000000;
+	}
+	return sum;
+}
+
+struct timeval time_divide(struct timeval t, unsigned long div)
+{
+	return time_from_usec(time_to_usec(t) / div);
+}
+
+struct timeval time_multiply(struct timeval t, unsigned long mult)
+{
+	return time_from_usec(time_to_usec(t) * mult);
+}
+
+uint64_t time_to_msec(struct timeval t)
+{
+	uint64_t msec;
+
+	msec = t.tv_usec / 1000 + (uint64_t)t.tv_sec * 1000;
+	return msec;
+}
+
+uint64_t time_to_usec(struct timeval t)
+{
+	uint64_t usec;
+
+	usec = t.tv_usec + (uint64_t)t.tv_sec * 1000000;
+	return usec;
+}
+
+struct timeval time_from_msec(uint64_t msec)
+{
+	struct timeval t;
+
+	t.tv_usec = (msec % 1000) * 1000;
+	t.tv_sec = msec / 1000;
+	return t;
+}
+
+struct timeval time_from_usec(uint64_t usec)
+{
+	struct timeval t;
+
+	t.tv_usec = usec % 1000000;
+	t.tv_sec = usec / 1000000;
+	return t;
+}

ccan/time/time.h

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+#ifndef CCAN_TIME_H
+#define CCAN_TIME_H
+#include "config.h"
+#include <sys/time.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+/**
+ * time_now - return the current time
+ *
+ * Example:
+ *	printf("Now is %lu seconds since epoch\n", (long)time_now().tv_sec);
+ */
+struct timeval time_now(void);
+
+/**
+ * time_greater - is a after b?
+ * @a: one time.
+ * @b: another time.
+ *
+ * Example:
+ *	static bool timed_out(const struct timeval *start)
+ *	{
+ *	#define TIMEOUT time_from_msec(1000)
+ *		return time_greater(time_now(), time_add(*start, TIMEOUT));
+ *	}
+ */
+bool time_greater(struct timeval a, struct timeval b);
+
+/**
+ * time_less - is a before b?
+ * @a: one time.
+ * @b: another time.
+ *
+ * Example:
+ *	static bool still_valid(const struct timeval *start)
+ *	{
+ *	#define TIMEOUT time_from_msec(1000)
+ *		return time_less(time_now(), time_add(*start, TIMEOUT));
+ *	}
+ */
+bool time_less(struct timeval a, struct timeval b);
+
+/**
+ * time_eq - is a equal to b?
+ * @a: one time.
+ * @b: another time.
+ *
+ * Example:
+ *	#include <sys/types.h>
+ *	#include <sys/wait.h>
+ *
+ *	// Can we fork in under a microsecond?
+ *	static bool fast_fork(void)
+ *	{
+ *		struct timeval start = time_now();
+ *		if (fork() != 0) {
+ *			exit(0);
+ *		}
+ *		wait(NULL);
+ *		return time_eq(start, time_now());
+ *	}
+ */
+bool time_eq(struct timeval a, struct timeval b);
+
+/**
+ * time_sub - subtract two times
+ * @recent: the larger (more recent) time.
+ * @old: the smaller (less recent) time.
+ *
+ * This returns a well formed struct timeval.
+ *
+ * Example:
+ *	static bool was_recent(const struct timeval *start)
+ *	{
+ *		return time_sub(time_now(), *start).tv_sec < 1;
+ *	}
+ */
+struct timeval time_sub(struct timeval recent, struct timeval old);
+
+/**
+ * time_add - add two times
+ * @a: one time.
+ * @b: another time.
+ *
+ * The times must not overflow, or the results are undefined.
+ *
+ * Example:
+ *	// We do one every second.
+ *	static struct timeval next_time(void)
+ *	{
+ *		return time_add(time_now(), time_from_msec(1000));
+ *	}
+ */
+struct timeval time_add(struct timeval a, struct timeval b);
+
+/**
+ * time_divide - divide a time by a value.
+ * @t: a time.
+ * @div: number to divide it by.
+ *
+ * Example:
+ *	// How long does it take to do a fork?
+ *	static struct timeval forking_time(void)
+ *	{
+ *		struct timeval start = time_now();
+ *		unsigned int i;
+ *
+ *		for (i = 0; i < 1000; i++) {
+ *			if (fork() != 0) {
+ *				exit(0);
+ *			}
+ *			wait(NULL);
+ *		}
+ *		return time_divide(time_sub(time_now(), start), i);
+ *	}
+ */
+struct timeval time_divide(struct timeval t, unsigned long div);
+
+/**
+ * time_multiply - multiply a time by a value.
+ * @t: a time.
+ * @mult: number to multiply it by.
+ *
+ * Example:
+ *	...
+ *	printf("Time to do 100000 forks would be %u sec\n",
+ *	       (unsigned)time_multiply(forking_time(), 1000000).tv_sec);
+ */
+struct timeval time_multiply(struct timeval t, unsigned long mult);
+
+/**
+ * time_to_msec - return number of milliseconds
+ * @t: a time
+ *
+ * It's often more convenient to deal with time values as
+ * milliseconds.  Note that this will fit into a 32-bit variable if
+ * it's a time difference of less than ~7 weeks.
+ *
+ * Example:
+ *	...
+ *	printf("Forking time is %u msec\n",
+ *	       (unsigned)time_to_msec(forking_time()));
+ */
+uint64_t time_to_msec(struct timeval t);
+
+/**
+ * time_to_usec - return number of microseconds
+ * @t: a time
+ *
+ * It's often more convenient to deal with time values as
+ * microseconds.  Note that this will fit into a 32-bit variable if
+ * it's a time difference of less than ~1 hour.
+ *
+ * Example:
+ *	...
+ *	printf("Forking time is %u usec\n",
+ *	       (unsigned)time_to_usec(forking_time()));
+ *
+ */
+uint64_t time_to_usec(struct timeval t);
+
+/**
+ * time_from_msec - convert milliseconds to a timeval
+ * @msec: time in milliseconds
+ *
+ * Example:
+ *	// 1/2 second timeout
+ *	#define TIMEOUT time_from_msec(500)
+ */
+struct timeval time_from_msec(uint64_t msec);
+
+/**
+ * time_from_usec - convert microseconds to a timeval
+ * @usec: time in microseconds
+ *
+ * Example:
+ *	// 1/2 second timeout
+ *	#define TIMEOUT time_from_usec(500000)
+ */
+struct timeval time_from_usec(uint64_t usec);
+
+#endif /* CCAN_TIME_H */