[TEST] make -j patch

This patch makes the '-j' argument to make(1) become a global limit
on number of jobs launched for all submakes in the build.

Today a "make -j 12" may start many more than 12 jobs because each
submake interprets the 12 without reference to other makes.

The patch uses a fifo to hold tokens allowing jobstarts.

Poul-Henning

Index: job.c
===================================================================
RCS file: /home/ncvs/src/usr.bin/make/job.c,v
retrieving revision 1.55
diff -u -r1.55 job.c
--- job.c	11 Nov 2004 12:52:15 -0000	1.55
+++ job.c	11 Nov 2004 19:15:30 -0000
_at__at_ -258,6 +258,8 _at__at_
 				 * jobs that were stopped due to concurrency
 				 * limits or externally */
 
+STATIC int	fifoFd;		/* Fd of our job fifo */
+STATIC char	fifoName[] = "/tmp/make_fifo_XXXXXXXXX";
 
 #if defined(USE_PGRP) && defined(SYSV)
 # define KILL(pid, sig)		killpg(-(pid), (sig))
_at__at_ -1091,6 +1093,8 _at__at_
 	Punt("Cannot fork");
     } else if (cpid == 0) {
 
+	if (fifoFd >= 0)
+	    close(fifoFd);
 	/*
 	 * Must duplicate the input stream down to the child's input and
 	 * reset it to the beginning (again). Since the stream was marked
_at__at_ -1891,9 +1895,10 _at__at_
 	return;
     }
 
-    while ((pid = waitpid((pid_t) -1, &status,
-			  (block?0:WNOHANG)|WUNTRACED)) > 0)
-    {
+    for (;;) {
+	pid = waitpid((pid_t) -1, &status, (block?0:WNOHANG)|WUNTRACED);
+	if (pid <= 0)
+	   break;
 	DEBUGF(JOB, ("Process %d exited or stopped.\n", pid));
 
 	jnode = Lst_Find(jobs, (void *)&pid, JobCmpPid);
_at__at_ -1915,8 +1920,17 _at__at_
 	    job = (Job *) Lst_Datum(jnode);
 	    (void) Lst_Remove(jobs, jnode);
 	    nJobs -= 1;
-	    DEBUGF(JOB, ("Job queue is no longer full.\n"));
-	    jobFull = FALSE;
+	    if (fifoFd >= 0 && nJobs > 0) {
+		write(fifoFd, "+", 1);
+		maxJobs--;
+		if (nJobs >= maxJobs)
+		    jobFull = TRUE;
+		else
+		    jobFull = FALSE;
+	    } else {
+	        DEBUGF(JOB, ("Job queue is no longer full.\n"));
+	        jobFull = FALSE;
+	    }
 	}
 
 	JobFinish(job, &status);
_at__at_ -1982,23 +1996,28 _at__at_
 	readfds = outputs;
 	timeout.tv_sec = SEL_SEC;
 	timeout.tv_usec = SEL_USEC;
+	if (jobFull && fifoFd >= 0)
+	    FD_SET(fifoFd, &readfds);
 
-	if ((nfds = select(FD_SETSIZE, &readfds, (fd_set *) 0,
-			   (fd_set *) 0, &timeout)) <= 0)
+	nfds = select(FD_SETSIZE, &readfds, (fd_set *) 0,
+			   (fd_set *) 0, &timeout);
+	if (nfds <= 0)
 	    return;
-	else {
-	    if (Lst_Open(jobs) == FAILURE) {
-		Punt("Cannot open job table");
-	    }
-	    while (nfds && (ln = Lst_Next(jobs)) != NULL) {
-		job = (Job *) Lst_Datum(ln);
-		if (FD_ISSET(job->inPipe, &readfds)) {
-		    JobDoOutput(job, FALSE);
-		    nfds -= 1;
-		}
+	if (fifoFd >= 0 && FD_ISSET(fifoFd, &readfds)) {
+	    if (--nfds <= 0)
+		return;
+	}
+	if (Lst_Open(jobs) == FAILURE) {
+	    Punt("Cannot open job table");
+	}
+	while (nfds && (ln = Lst_Next(jobs)) != NULL) {
+	    job = (Job *) Lst_Datum(ln);
+	    if (FD_ISSET(job->inPipe, &readfds)) {
+		JobDoOutput(job, FALSE);
+		nfds -= 1;
 	    }
-	    Lst_Close(jobs);
 	}
+	Lst_Close(jobs);
 #endif /* !USE_KQUEUE */
     }
 }
_at__at_ -2055,19 +2074,62 _at__at_
 Job_Init(int maxproc)
 {
     GNode         *begin;     /* node for commands to do at the very start */
+    const char	  *env;
 
+    fifoFd =	  -1;
     jobs =  	  Lst_Init(FALSE);
     stoppedJobs = Lst_Init(FALSE);
-    maxJobs = 	  maxproc;
+    env = getenv("MAKE_JOBS_FIFO");
+    if (env == NULL && maxproc > 1) {
+	/*
+	 * We did not find the environment variable so we are the leader.
+	 * Create the fifo, open it, write one char per allowed job into
+	 * the pipe.
+	 */
+	mktemp(fifoName);
+        if (!mkfifo(fifoName, 0600)) {
+	    fifoFd = open(fifoName, O_RDWR | O_NONBLOCK, 0);
+	    if (fifoFd >= 0) {
+		fcntl(fifoFd, F_SETFL, O_NONBLOCK);
+	        env = fifoName;
+	        setenv("MAKE_JOBS_FIFO", env, 1);
+	        while (maxproc-- > 0)
+		    write(fifoFd, "+", 1);
+		/*The master make does not get a magic token */
+                jobFull = TRUE;
+		maxJobs = 0;
+	    } else {
+	        unlink(fifoName);
+	        env = NULL;
+            }
+	}
+    } else if (env != NULL) {
+	/*
+	 * We had the environment variable so we are a slave.
+	 * Open fifo and give ourselves a magic token which represents
+	 * the token our parent make has grabbed to start his make process.
+	 * Otherwise the sub-makes would gobble up tokens and the proper
+	 * number of tokens to specify to -j would depend on the depth of		 * the tree and the order of execution.
+	 */
+	fifoFd = open(env, O_RDWR, 0);
+	if (fifoFd >= 0) {
+	    fcntl(fifoFd, F_SETFL, O_NONBLOCK);
+	    maxJobs = 1;
+	    jobFull = FALSE;
+	}
+    }
+    if (fifoFd <= 0) {
+	maxJobs = maxproc;
+        jobFull = FALSE;
+    }
     nJobs = 	  0;
-    jobFull = 	  FALSE;
 
     aborting = 	  0;
     errors = 	  0;
 
     lastNode =	  NULL;
 
-    if (maxJobs == 1 || beVerbose == 0) {
+    if ((maxJobs == 1 && fifoFd < 0) || beVerbose == 0) {
 	/*
 	 * If only one job can run at a time, there's no need for a banner,
 	 * no is there?
_at__at_ -2157,7 +2219,19 _at__at_
 Boolean
 Job_Full(void)
 {
-    return(aborting || jobFull);
+    char c;
+    int i;
+
+    if (aborting)
+	return(aborting);
+    if (fifoFd >= 0 && jobFull) {
+	i = read(fifoFd, &c, 1);
+	if (i > 0) {
+	    maxJobs++;
+	    jobFull = FALSE;
+	}
+    }
+    return(jobFull);
 }
 
 /*-
_at__at_ -2485,6 +2559,8 _at__at_
 	    }
 	}
     }
+    if (fifoFd >= 0)
+	unlink(fifoName);
     return(errors);
 }
 
Index: make.c
===================================================================
RCS file: /home/ncvs/src/usr.bin/make/make.c,v
retrieving revision 1.24
diff -u -r1.24 make.c
--- make.c	23 Oct 2002 23:16:43 -0000	1.24
+++ make.c	11 Nov 2004 14:36:35 -0000
_at__at_ -637,7 +637,7 _at__at_
 {
     GNode	*gn;
 
-    while (!Job_Full() && !Lst_IsEmpty (toBeMade)) {
+    while (!Lst_IsEmpty (toBeMade) && !Job_Full()) {
 	gn = (GNode *) Lst_DeQueue (toBeMade);
 	DEBUGF(MAKE, ("Examining %s...", gn->name));
 	/*
-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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Never attribute to malice what can adequately be explained by incompetence.