ring broadcastthread

1 files changed, 58 insertions, 104 deletions

diff --git a/balls.c b/balls.c
index f156aab..adf7964 100644
--- a/balls.c
+++ b/balls.c
@@ -39,20 +39,19 @@ typedef struct {
 
 	Channel *frametick;
 
-	Channel **in; /* <-chan Ball */
-	Channel **out; /* chan<- Ball */
+	/* threads communicate in a ring */
+	Channel *lneighbor; /* <-chan Ball */
+	Channel *rneighbor; /* chan<- Ball */
 	int nothers; /* number of other balls */
 } BallArg;
 
 static int ballcolors[] = { DRed, DGreen, DBlue };
-static uint radii[] = { 20, 30, 50 };
+static uint radii[] = { 24, 32, 48 };
 static Rectangle bounds = {{0, 0}, {WIDTH, HEIGHT}};
 
-int init(char *label, Mousectl **mctl, Keyboardctl **kctl);
 void spawnballs(int n);
+void eventloop(Image *bg, Image *walls);
 Channel **allocchans(int nchans, int elsize, int nel);
-void mcopycolskip(Channel *vec[], Channel **matrix[], int n, int col, int skip);
-void vcopyskip(Channel *dst[], Channel *src[], int n, int skip);
 void nooverlapcircles(Point centers[], int n, uint radius);
 Point randptinrect(Rectangle r);
 int randint(int lo, int hi);
@@ -60,17 +59,12 @@ uint maxelem(uint arr[], uint n);
 double mass(uint radius);
 double area(double radius);
 void ball(void *arg);
-void broadcast(Channel *cs[], int n, void *v);
 void frametick(void *arg);
 
 void
 threadmain(int argc, char *argv[]) {
 	int nballs;
 	Image *bg, *walls;
-	Mousectl *mctl;
-	Keyboardctl *kctl;
-	int resize[2];
-	Rune key;
 
 	nballs = DEFAULT_NBALLS;
 	if (argc > 1) {
@@ -81,8 +75,8 @@ threadmain(int argc, char *argv[]) {
 	}
 	printf("nballs: %ud\n", nballs);
 
-	if (init(argv[0], &mctl, &kctl))
-		sysfatal("%s: %r", argv[0]);
+	if (initdraw(nil, nil, "Balls") < 0)
+		sysfatal("initdraw() failed\n");
 
 	printf("screen: (%d,%d) (%d,%d)\n", screen->r.min.x, screen->r.min.y,
 		screen->r.max.x, screen->r.max.y);
@@ -98,47 +92,16 @@ threadmain(int argc, char *argv[]) {
 
 	spawnballs(nballs);
 
-	enum { RESIZE = 0, KEYBD = 1 };
-	Alt alts[3] = {
-		{mctl->resizec, &resize, CHANRCV},
-		{kctl->c, &key, CHANRCV},
-		{nil, nil, CHANEND},
-	};
-	for (;;) {
-		switch (alt(alts)) {
-		case RESIZE:
-			if (getwindow(display, Refnone) < 0)
-				sysfatal("%s: %r", argv[0]);
-			drawbg(walls, bg);
-			break;
-		case KEYBD:
-			if (key == KEY_QUIT)
-				threadexitsall(0);
-			break;
-		case -1: /* interrupted */
-			break;
-		}
-	}
-}
-
-int
-init(char *label, Mousectl **mctl, Keyboardctl **kctl) {
-	if (initdraw(nil, nil, label) < 0)
-		return 1;
-	if ((*mctl = initmouse(nil, screen)) == nil)
-		return 1;
-	if ((*kctl = initkeyboard(nil)) == nil)
-		return 1;
-	return 0;
+	eventloop(bg, walls);
 }
 
 void
 spawnballs(int n) {
 	Channel **ticks;
 	Point *ps;
-	int i, j;
+	int i;
 	BallArg *arg;
-	Channel ***cs;
+	Channel **cs;
 
 	if ((ticks = allocchans(n, sizeof(int), TICK_BUFSIZE)) == nil)
 		sysfatal("failed to allocate frame ticker channels");
@@ -149,17 +112,11 @@ spawnballs(int n) {
 		sysfatal("failed to allocate position array");
 	nooverlapcircles(ps, n, maxelem(radii, NELEMS(radii)));
 
-	if ((cs = malloc(n*sizeof(Channel **))) == nil)
+	if ((cs = malloc(n*sizeof(Channel *))) == nil)
 		sysfatal("failed to allocate channel matrix");
 	for (i = 0; i < n; i++) {
-		if ((cs[i] = malloc(n*sizeof(Channel *))) == nil)
-			sysfatal("failed to allocate row of channel matrix");
-		for (j = 0; j < n; j++) {
-			if (j == i)
-				continue;
-			if ((cs[i][j] = chancreate(sizeof(Ball), BALL_BUFSIZE)) == nil)
-				sysfatal("failed to create channel");
-		}
+		if ((cs[i] = chancreate(sizeof(Ball), BALL_BUFSIZE)) == nil)
+			sysfatal("failed to create channel");
 	}
 
 	for (i = 0; i < n; i++) {
@@ -170,19 +127,10 @@ spawnballs(int n) {
 		arg->b.v = V((double) randint(-VMAX, VMAX+1), (double) randint(-VMAX, VMAX+1));
 		arg->b.r = radii[randint(0, NELEMS(radii))];
 		arg->b.m = mass(arg->b.r);
-
 		arg->color = ballcolors[randint(0, NELEMS(ballcolors))];
-
 		arg->frametick = ticks[i];
-
-		if ((arg->in = malloc((n-1)*sizeof(Channel *))) == nil)
-			sysfatal("failed to allocate array of incoming channels");
-		mcopycolskip(arg->in, cs, n, i, i);
-
-		if ((arg->out = malloc((n-1)*sizeof(Channel *))) == nil)
-			sysfatal("failed to allocate array of outgoing channels");
-		vcopyskip(arg->out, cs[i], n, i);
-
+		arg->lneighbor = cs[i];
+		arg->rneighbor = cs[(i+1) % n];
 		arg->nothers = n-1;
 
 		printf("create ball p(%d,%d) v(%f,%f) r(%u) m(%f)\n", arg->b.p.x, arg->b.p.y, arg->b.v.x, arg->b.v.y, arg->b.r, arg->b.m);
@@ -190,11 +138,45 @@ spawnballs(int n) {
 	}
 
 	free(ps);
-	for (i = 0; i < n; i++)
-		free(cs[i]);
 	free(cs);
 }
 
+void
+eventloop(Image *bg, Image *walls) {
+	Mousectl *mctl;
+	Keyboardctl *kctl;
+	int resize[2];
+	Rune key;
+
+	if ((mctl = initmouse(nil, screen)) == nil)
+		sysfatal("failed to initialize mouse\n");
+	if ((kctl = initkeyboard(nil)) == nil)
+		sysfatal("failed to initialize keyboard\n");
+
+	enum { RESIZE = 0, KEYBD = 1 };
+	Alt alts[3] = {
+		{mctl->resizec, &resize, CHANRCV},
+		{kctl->c, &key, CHANRCV},
+		{nil, nil, CHANEND},
+	};
+	for (;;) {
+		switch (alt(alts)) {
+		case RESIZE:
+			if (getwindow(display, Refnone) < 0)
+				sysfatal("getwindow() failed\n");
+			drawbg(walls, bg);
+			break;
+		case KEYBD:
+			if (key == KEY_QUIT)
+				threadexitsall(0);
+			break;
+		case -1: /* interrupted */
+			break;
+		}
+	}
+}
+
+/* allocate nil-terminated array of channels */
 Channel **
 allocchans(int nchans, int elsize, int nel) {
 	Channel **cs;
@@ -217,28 +199,7 @@ allocchans(int nchans, int elsize, int nel) {
 	return cs;
 }
 
-/* copy column col of nxn matrix, except for element skip, into n-1 length vec */
-void
-mcopycolskip(Channel *vec[], Channel **matrix[], int n, int col, int skip) {
-	int i;
-
-	for (i = 0; i < skip; i++)
-		vec[i] = matrix[i][col];
-	for (i = skip+1; i < n; i++)
-		vec[i-1] = matrix[i][col];
-}
-
-/* copy each element in n-length src, except for element skip, into n-1 length dst */
-void
-vcopyskip(Channel *dst[], Channel *src[], int n,  int skip) {
-	int i;
-
-	for (i = 0; i < skip; i++)
-		dst[i] = src[i];
-	for (i = skip+1; i < n; i++)
-		dst[i-1] = src[i];
-}
-
+/* populate array of circle coordinates within bounds so that circles don't overlap */
 void
 nooverlapcircles(Point centers[], int n, uint radius) {
 	int i, j;
@@ -305,38 +266,31 @@ ball(void *arg) {
 	if (fill == nil ||erase == nil)
 		sysfatal("failed to allocate image");
 
-	oldpos = b.p;
+	oldpos = b.p; /* keep track of previous position so it can be erased */
 	for (;;) {
 		b.v.y += G;
-
 		b.p = ptaddv(b.p, b.v);
 
 		printf("(%d,%d) %f %f\n", b.p.x, b.p.y, b.v.x, b.v.y);
 
-		broadcast(barg->out, barg->nothers, &b);
-
 		/* check for ball collision */
+		other = b; /* send our own ball first */
 		for (i = 0; i < barg->nothers; i++) {
-			recv(barg->in[i], &other);
+			send(barg->rneighbor, &other); /* pass balls around the ring */
+			recv(barg->lneighbor, &other);
 			collideball(&b, &other);
 		}		
 
 		collidewall(&b, bounds);
 
-		recv(barg->frametick, &t);
+		recv(barg->frametick, &t); /* wait for next frame */
 		drawcircle(erase, oldpos);
 		drawcircle(fill, b.p);
 		oldpos = b.p;
-
 	}	
 }
 
-void
-broadcast(Channel *cs[], int n, void *v) {
-	while (n-- > 0)
-		send(cs[n], v);
-}
-
+/* arg is nil-terminated array of chan int */
 void
 frametick(void *arg) {
 	Channel **cs, **c;