ccan/ccan/lbalance/_info

/* Licensed under GPLv3+ - see LICENSE file for details */
#include "config.h"
#include <string.h>

/**
 * lbalance - helpers for loadbalancing parallel tasks
 *
 * This code helps when you have a large number of one-shot tasks; it tries
 * to determine the maximum amount of useful parallelism.
 *
 * License: GPL
 * Author: Rusty Russell <rusty@rustcorp.com.au>
 *
 * Example:
 *	// Run 1000 of the given commandline at best-known parallel rate.
 *	// See tools/lbalance.c for a sligtly more serious example.
 *	#include <ccan/lbalance/lbalance.h>
 *      #include <sys/types.h>
 *      #include <sys/time.h>
 *      #include <sys/resource.h>
 *      #include <sys/wait.h>
 *      #include <err.h>
 *
 *	#define MAX 1000
 *
 *	static pid_t spawn(char *args[])
 *	{
 *		pid_t pid = fork();
 *
 *		if (pid == -1)
 *			err(1, "forking");
 *		if (pid == 0) {
 *			execvp(args[0], args);
 *			err(1, "exec failed");
 *		}
 *		return pid;
 *	}
 *
 *	int main(int argc, char *argv[])
 *	{
 *		unsigned int num = 0, num_running = 0;
 *		pid_t pids[MAX];
 *		struct lbalance_task *tasks[MAX];
 *		struct lbalance *lb;
 *
 *		if (argc == 1)
 *			errx(1, "Usage: %s cmdline...", argv[0]);
 *
 *		lb = lbalance_new();
 *
 *		while (num - num_running < MAX) {
 *			struct rusage ru;
 *			pid_t pid;
 *			unsigned int i;
 *
 *			// Make sure we're running as many as lbalance says to. 
 *			while (num_running < lbalance_target(lb) && num < MAX) {
 *				pids[num] = spawn(argv+1);
 *				tasks[num] = lbalance_task_new(lb);
 *				num++;
 *				num_running++;
 *			}
 *
 *			// Now wait for something to die.
 *			pid = wait3(NULL, 0, &ru);
 *			// Find it, tell lbalance it's finished.
 *			for (i = 0; i < num; i++) {
 *				if (pids[i] == pid) {
 *					lbalance_task_free(tasks[i], &ru);
 *					pids[i] = 0;
 *					break;
 *				}
 *			}
 *			num_running--;
 *		}
 *		lbalance_free(lb);
 *		return 0;
 *	}
 */
int main(int argc, char *argv[])
{
	/* Expect exactly one argument */
	if (argc != 2)
		return 1;

	if (strcmp(argv[1], "depends") == 0) {
		printf("ccan/tlist\n");
		return 0;
	}

	return 1;
}