X-Git-Url: https://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Flbalance%2F_info;fp=ccan%2Flbalance%2F_info;h=e3e9c78e7a32434f858f27a2c4533f8b2afc1bdd;hp=c0d0ab0e5a4fa7fb362b0ebb8a0a15da53ee9627;hb=c10ed33172acfd5126a82cd11b1476d5c9a8aa9f;hpb=f69389e6806e2f0b63084576ffa4c84bba699147

diff --git a/ccan/lbalance/_info b/ccan/lbalance/_info
index c0d0ab0e..e3e9c78e 100644
--- a/ccan/lbalance/_info
+++ b/ccan/lbalance/_info
@@ -9,6 +9,72 @@
  *
  * 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[])
 {