82  * sends writeheader()'s and lists of daddr's to the workers via pipes.
83  * The following structure defines the instruction packets sent to workers.
91 #define WORKERS 3		/* 1 worker writing, 1 reading, 1 for slack */  macro
103 } workers[WORKERS+1];  variable
139 	for (i = 0; i <= WORKERS; i++) {  in alloctape()
144 		workers[i].tblock = (char (*)[TP_BSIZE])  in alloctape()
146 		workers[i].req = (struct req *)workers[i].tblock - ntrec - 1;  in alloctape()
148 	wp = &workers[0];  in alloctape()
238 	if (++wp >= &workers[WORKERS])  in flushtape()
239 		wp = &workers[0];  in flushtape()
258 			for (i = 0; i < WORKERS; i++) {  in flushtape()
259 				if (workers[i].sent) {  in flushtape()
260 					if (atomic_read(workers[i].fd,  in flushtape()
266 					workers[i].sent = 0;  in flushtape()
308 	for (f = 0; f < WORKERS; f++) {  in trewind()
317 		if (workers[f].sent) {  in trewind()
318 			if (atomic_read(workers[f].fd, (void *)&got, sizeof got)  in trewind()
323 			workers[f].sent = 0;  in trewind()
330 		(void) close(workers[f].fd);  in trewind()
332 	while (wait((int *)NULL) >= 0)	/* wait for any signals from workers */  in trewind()
396 	twp = &workers[WORKERS];  in rollforward()
400 	 * Each of the N workers should have requests that need to  in rollforward()
402 	 * (workers[WORKERS]) to construct request lists to be sent to  in rollforward()
405 	for (i = 0; i < WORKERS; i++) {  in rollforward()
447 		if (++wp >= &workers[WORKERS])  in rollforward()
448 			wp = &workers[0];  in rollforward()
478 	 * Clear the first workers' response.  One hopes that it  in rollforward()
630 		create_workers();  /* Share open tape file descriptor with workers */  in startnewtape()
682  * proceed - handler for SIGUSR2, used to synchronize IO between the workers.
706 	for (i = 0; i < WORKERS; i++) {  in create_workers()
707 		if (i == wp - &workers[0]) {  in create_workers()
714 		    (workers[i].pid = fork()) < 0)  in create_workers()
715 			quit("too many workers, %d (recompile smaller): %s\n",  in create_workers()
718 		workers[i].fd = cmd[1];  in create_workers()
719 		workers[i].sent = 0;  in create_workers()
720 		if (workers[i].pid == 0) { 	    /* Worker starts up here */  in create_workers()
722 			        (void) close(workers[j].fd);  in create_workers()
729 	for (i = 0; i < WORKERS; i++)  in create_workers()
730 		(void) atomic_write(workers[i].fd,  in create_workers()
731 			      (const void *) &workers[(i + 1) % WORKERS].pid,  in create_workers()
732 		              sizeof workers[0].pid);  in create_workers()
742 	for (i = 0; i < WORKERS; i++)  in killall()
743 		if (workers[i].pid > 0) {  in killall()
744 			(void) kill(workers[i].pid, SIGKILL);  in killall()
745 			workers[i].sent = 0;  in killall()