Instead of sending all data to control mode clients as fast as possible,

add a limit of how much data will be sent to the client and try to use
it for panes with some degree of fairness. GitHub issue 2217, with
George Nachman.

1 files changed, 384 insertions, 92 deletions

diff --git a/control.c b/control.c
index 7e1a869b..c1e0b7eb 100644
--- a/control.c
+++ b/control.c
@@ -27,112 +27,183 @@
 
 #include "tmux.h"
 
-/* Control client offset. */
-struct control_offset {
-	u_int				pane;
+/*
+ * Block of data to output. Each client has one "all" queue of blocks and
+ * another queue for each pane (in struct client_offset). %output blocks are
+ * added to both queues and other output lines (notifications) added only to
+ * the client queue.
+ *
+ * When a client becomes writeable, data from blocks on the pane queue are sent
+ * up to the maximum size (CLIENT_BUFFER_HIGH). If a block is entirely written,
+ * it is removed from both pane and client queues and if this means non-%output
+ * blocks are now at the head of the client queue, they are written.
+ *
+ * This means a %output block holds up any subsequent non-%output blocks until
+ * it is written which enforces ordering even if the client cannot accept the
+ * entire block in one go.
+ */
+struct control_block {
+	size_t				 size;
+	char				*line;
+
+	TAILQ_ENTRY(control_block)	 entry;
+	TAILQ_ENTRY(control_block)	 all_entry;
+ };
+
+/* Control client pane. */
+struct control_pane {
+	u_int				 pane;
+
+	/*
+	 * Offsets into the pane data. The first (offset) is the data we have
+	 * written; the second (queued) the data we have queued (pointed to by
+	 * a block).
+	 */
+	struct window_pane_offset	 offset;
+	struct window_pane_offset	 queued;
+
+	int				 flags;
+#define CONTROL_PANE_OFF 0x1
 
-	struct window_pane_offset	offset;
-	int				flags;
-#define CONTROL_OFFSET_OFF 0x1
+	int				 pending_flag;
+	TAILQ_ENTRY(control_pane)	 pending_entry;
 
-	RB_ENTRY(control_offset)	entry;
+	TAILQ_HEAD(, control_block)	 blocks;
+
+	RB_ENTRY(control_pane)		 entry;
 };
-RB_HEAD(control_offsets, control_offset);
+RB_HEAD(control_panes, control_pane);
 
 /* Control client state. */
 struct control_state {
-	struct control_offsets	 offsets;
+	struct control_panes		 panes;
+
+	TAILQ_HEAD(, control_pane)	 pending_list;
+	u_int				 pending_count;
 
-	struct bufferevent	*read_event;
-	struct bufferevent	*write_event;
+	TAILQ_HEAD(, control_block)	 all_blocks;
+
+	struct bufferevent		*read_event;
+	struct bufferevent		*write_event;
 };
 
-/* Compare client offsets. */
+/* Low watermark. */
+#define CONTROL_BUFFER_LOW 512
+#define CONTROL_BUFFER_HIGH 8192
+
+/* Minimum to write to each client. */
+#define CONTROL_WRITE_MINIMUM 32
+
+/* Flags to ignore client. */
+#define CONTROL_IGNORE_FLAGS \
+	(CLIENT_CONTROL_NOOUTPUT| \
+	 CLIENT_UNATTACHEDFLAGS)
+
+/* Compare client panes. */
 static int
-control_offset_cmp(struct control_offset *co1, struct control_offset *co2)
+control_pane_cmp(struct control_pane *cp1, struct control_pane *cp2)
 {
-	if (co1->pane < co2->pane)
+	if (cp1->pane < cp2->pane)
 		return (-1);
-	if (co1->pane > co2->pane)
+	if (cp1->pane > cp2->pane)
 		return (1);
 	return (0);
 }
-RB_GENERATE_STATIC(control_offsets, control_offset, entry, control_offset_cmp);
+RB_GENERATE_STATIC(control_panes, control_pane, entry, control_pane_cmp);
+
+/* Free a block. */
+static void
+control_free_block(struct control_state *cs, struct control_block *cb)
+{
+	free(cb->line);
+	TAILQ_REMOVE(&cs->all_blocks, cb, all_entry);
+	free(cb);
+}
 
 /* Get pane offsets for this client. */
-static struct control_offset *
-control_get_offset(struct client *c, struct window_pane *wp)
+static struct control_pane *
+control_get_pane(struct client *c, struct window_pane *wp)
 {
 	struct control_state	*cs = c->control_state;
-	struct control_offset	 co = { .pane = wp->id };
+	struct control_pane	 cp = { .pane = wp->id };
 
-	return (RB_FIND(control_offsets, &cs->offsets, &co));
+	return (RB_FIND(control_panes, &cs->panes, &cp));
 }
 
 /* Add pane offsets for this client. */
-static struct control_offset *
-control_add_offset(struct client *c, struct window_pane *wp)
+static struct control_pane *
+control_add_pane(struct client *c, struct window_pane *wp)
 {
 	struct control_state	*cs = c->control_state;
-	struct control_offset	*co;
+	struct control_pane	*cp;
+
+	cp = control_get_pane(c, wp);
+	if (cp != NULL)
+		return (cp);
+
+	cp = xcalloc(1, sizeof *cp);
+	cp->pane = wp->id;
+	RB_INSERT(control_panes, &cs->panes, cp);
 
-	co = control_get_offset(c, wp);
-	if (co != NULL)
-		return (co);
+	memcpy(&cp->offset, &wp->offset, sizeof cp->offset);
+	memcpy(&cp->queued, &wp->offset, sizeof cp->queued);
+	TAILQ_INIT(&cp->blocks);
 
-	co = xcalloc(1, sizeof *co);
-	co->pane = wp->id;
-	RB_INSERT(control_offsets, &cs->offsets, co);
-	memcpy(&co->offset, &wp->offset, sizeof co->offset);
-	return (co);
+	return (cp);
 }
 
-/* Free control offsets. */
+/* Reset control offsets. */
 void
-control_free_offsets(struct client *c)
+control_reset_offsets(struct client *c)
 {
 	struct control_state	*cs = c->control_state;
-	struct control_offset	*co, *co1;
+	struct control_pane	*cp, *cp1;
 
-	RB_FOREACH_SAFE(co, control_offsets, &cs->offsets, co1) {
-		RB_REMOVE(control_offsets, &cs->offsets, co);
-		free(co);
+	RB_FOREACH_SAFE(cp, control_panes, &cs->panes, cp1) {
+		RB_REMOVE(control_panes, &cs->panes, cp);
+		free(cp);
 	}
+
+	TAILQ_INIT(&cs->pending_list);
+	cs->pending_count = 0;
 }
 
 /* Get offsets for client. */
 struct window_pane_offset *
 control_pane_offset(struct client *c, struct window_pane *wp, int *off)
 {
-	struct control_offset	*co;
+	struct control_state	*cs = c->control_state;
+	struct control_pane	*cp;
 
 	if (c->flags & CLIENT_CONTROL_NOOUTPUT) {
 		*off = 0;
 		return (NULL);
 	}
 
-	co = control_get_offset(c, wp);
-	if (co == NULL) {
+	cp = control_get_pane(c, wp);
+	if (cp == NULL) {
 		*off = 0;
 		return (NULL);
 	}
-	if (co->flags & CONTROL_OFFSET_OFF) {
+	if (cp->flags & CONTROL_PANE_OFF) {
 		*off = 1;
 		return (NULL);
 	}
-	return (&co->offset);
+	*off = (EVBUFFER_LENGTH(cs->write_event->output) >= CONTROL_BUFFER_LOW);
+	return (&cp->offset);
 }
 
 /* Set pane as on. */
 void
 control_set_pane_on(struct client *c, struct window_pane *wp)
 {
-	struct control_offset	*co;
+	struct control_pane	*cp;
 
-	co = control_get_offset(c, wp);
-	if (co != NULL) {
-		co->flags &= ~CONTROL_OFFSET_OFF;
-		memcpy(&co->offset, &wp->offset, sizeof co->offset);
+	cp = control_get_pane(c, wp);
+	if (cp != NULL) {
+		cp->flags &= ~CONTROL_PANE_OFF;
+		memcpy(&cp->offset, &wp->offset, sizeof cp->offset);
+		memcpy(&cp->queued, &wp->offset, sizeof cp->queued);
 	}
 }
 
@@ -140,70 +211,104 @@ control_set_pane_on(struct client *c, struct window_pane *wp)
 void
 control_set_pane_off(struct client *c, struct window_pane *wp)
 {
-	struct control_offset	*co;
+	struct control_pane	*cp;
 
-	co = control_add_offset(c, wp);
-	co->flags |= CONTROL_OFFSET_OFF;
+	cp = control_add_pane(c, wp);
+	cp->flags |= CONTROL_PANE_OFF;
 }
 
 /* Write a line. */
-void
-control_write(struct client *c, const char *fmt, ...)
+static void
+control_vwrite(struct client *c, const char *fmt, va_list ap)
 {
 	struct control_state	*cs = c->control_state;
-	va_list			 ap;
 	char			*s;
 
-	va_start(ap, fmt);
 	xvasprintf(&s, fmt, ap);
-	va_end(ap);
+	log_debug("%s: %s: writing line: %s", __func__, c->name, s);
 
 	bufferevent_write(cs->write_event, s, strlen(s));
 	bufferevent_write(cs->write_event, "\n", 1);
+
+	bufferevent_enable(cs->write_event, EV_WRITE);
 	free(s);
 }
 
+/* Write a line. */
+void
+control_write(struct client *c, const char *fmt, ...)
+{
+	struct control_state	*cs = c->control_state;
+	struct control_block	*cb;
+	va_list			 ap;
+
+	va_start(ap, fmt);
+
+	if (TAILQ_EMPTY(&cs->all_blocks)) {
+		control_vwrite(c, fmt, ap);
+		va_end(ap);
+		return;
+	}
+
+	cb = xcalloc(1, sizeof *cb);
+	xvasprintf(&cb->line, fmt, ap);
+	TAILQ_INSERT_TAIL(&cs->all_blocks, cb, all_entry);
+
+	log_debug("%s: %s: storing line: %s", __func__, c->name, cb->line);
+	bufferevent_enable(cs->write_event, EV_WRITE);
+
+	va_end(ap);
+}
+
 /* Write output from a pane. */
 void
 control_write_output(struct client *c, struct window_pane *wp)
 {
 	struct control_state	*cs = c->control_state;
-	struct control_offset	*co;
-	struct evbuffer		*message;
-	u_char			*new_data;
-	size_t			 new_size, i;
+	struct control_pane	*cp;
+	struct control_block	*cb;
+	size_t			 new_size;
 
-	if (c->flags & CLIENT_CONTROL_NOOUTPUT)
-		return;
 	if (winlink_find_by_window(&c->session->windows, wp->window) == NULL)
 		return;
 
-	co = control_add_offset(c, wp);
-	if (co->flags & CONTROL_OFFSET_OFF) {
-		window_pane_update_used_data(wp, &co->offset, SIZE_MAX, 1);
+	if (c->flags & CONTROL_IGNORE_FLAGS) {
+		cp = control_get_pane(c, wp);
+		if (cp != NULL)
+			goto ignore;
 		return;
 	}
-	new_data = window_pane_get_new_data(wp, &co->offset, &new_size);
+	cp = control_add_pane(c, wp);
+	if (cp->flags & CONTROL_PANE_OFF)
+		goto ignore;
+
+	window_pane_get_new_data(wp, &cp->queued, &new_size);
 	if (new_size == 0)
 		return;
-
-	message = evbuffer_new();
-	if (message == NULL)
-		fatalx("out of memory");
-	evbuffer_add_printf(message, "%%output %%%u ", wp->id);
-
-	for (i = 0; i < new_size; i++) {
-		if (new_data[i] < ' ' || new_data[i] == '\\')
-			evbuffer_add_printf(message, "\\%03o", new_data[i]);
-		else
-			evbuffer_add_printf(message, "%c", new_data[i]);
+	window_pane_update_used_data(wp, &cp->queued, new_size);
+
+	cb = xcalloc(1, sizeof *cb);
+	cb->size = new_size;
+	TAILQ_INSERT_TAIL(&cs->all_blocks, cb, all_entry);
+
+	TAILQ_INSERT_TAIL(&cp->blocks, cb, entry);
+	log_debug("%s: %s: new output block of %zu for %%%u", __func__, c->name,
+	    cb->size, wp->id);
+
+	if (!cp->pending_flag) {
+		log_debug("%s: %s: %%%u now pending", __func__, c->name,
+		    wp->id);
+		TAILQ_INSERT_TAIL(&cs->pending_list, cp, pending_entry);
+		cp->pending_flag = 1;
+		cs->pending_count++;
 	}
-	evbuffer_add(message, "\n", 1);
-
-	bufferevent_write_buffer(cs->write_event, message);
-	evbuffer_free(message);
+	bufferevent_enable(cs->write_event, EV_WRITE);
+	return;
 
-	window_pane_update_used_data(wp, &co->offset, new_size, 1);
+ignore:
+	log_debug("%s: %s: ignoring pane %%%u", __func__, c->name, wp->id);
+	window_pane_update_used_data(wp, &cp->offset, SIZE_MAX);
+	window_pane_update_used_data(wp, &cp->queued, SIZE_MAX);
 }
 
 /* Control client error callback. */
@@ -246,8 +351,8 @@ control_read_callback(__unused struct bufferevent *bufev, void *data)
 		line = evbuffer_readln(buffer, NULL, EVBUFFER_EOL_LF);
 		if (line == NULL)
 			break;
-		log_debug("%s: %s", __func__, line);
-		if (*line == '\0') { /* empty line exit */
+		log_debug("%s: %s: %s", __func__, c->name, line);
+		if (*line == '\0') { /* empty line detach */
 			free(line);
 			c->flags |= CLIENT_EXIT;
 			break;
@@ -263,6 +368,168 @@ control_read_callback(__unused struct bufferevent *bufev, void *data)
 	}
 }
 
+/* Does this control client have outstanding data to write? */
+int
+control_all_done(struct client *c)
+{
+	struct control_state	*cs = c->control_state;
+
+	if (!TAILQ_EMPTY(&cs->all_blocks))
+		return (0);
+	return (EVBUFFER_LENGTH(cs->write_event->output) == 0);
+}
+
+/* Flush all blocks until output. */
+static void
+control_flush_all_blocks(struct client *c)
+{
+	struct control_state	*cs = c->control_state;
+	struct control_block	*cb, *cb1;
+
+	TAILQ_FOREACH_SAFE(cb, &cs->all_blocks, all_entry, cb1) {
+		if (cb->size != 0)
+			break;
+		log_debug("%s: %s: flushing line: %s", __func__, c->name,
+		    cb->line);
+
+		bufferevent_write(cs->write_event, cb->line, strlen(cb->line));
+		bufferevent_write(cs->write_event, "\n", 1);
+		control_free_block(cs, cb);
+	}
+}
+
+/* Append data to buffer. */
+static struct evbuffer *
+control_append_data(struct control_pane *cp, struct evbuffer *message,
+    struct window_pane *wp, size_t size)
+{
+	u_char	*new_data;
+	size_t	 new_size;
+	u_int	 i;
+
+	if (message == NULL) {
+		message = evbuffer_new();
+		if (message == NULL)
+			fatalx("out of memory");
+		evbuffer_add_printf(message, "%%output %%%u ", wp->id);
+	}
+
+	new_data = window_pane_get_new_data(wp, &cp->offset, &new_size);
+	if (new_size < size)
+		fatalx("not enough data: %zu < %zu", new_size, size);
+	for (i = 0; i < size; i++) {
+		if (new_data[i] < ' ' || new_data[i] == '\\')
+			evbuffer_add_printf(message, "\\%03o", new_data[i]);
+		else
+			evbuffer_add_printf(message, "%c", new_data[i]);
+	}
+	window_pane_update_used_data(wp, &cp->offset, size);
+	return (message);
+}
+
+/* Write buffer. */
+static void
+control_write_data(struct client *c, struct evbuffer *message)
+{
+	struct control_state	*cs = c->control_state;
+
+	log_debug("%s: %s: %.*s", __func__, c->name,
+	    (int)EVBUFFER_LENGTH(message), EVBUFFER_DATA(message));
+
+	evbuffer_add(message, "\n", 1);
+	bufferevent_write_buffer(cs->write_event, message);
+	evbuffer_free(message);
+}
+
+/* Write output to client. */
+static int
+control_write_pending(struct client *c, struct control_pane *cp, size_t limit)
+{
+	struct control_state	*cs = c->control_state;
+	struct session		*s = c->session;
+	struct window_pane	*wp = NULL;
+	struct evbuffer		*message = NULL;
+	size_t			 used = 0, size;
+	struct control_block	*cb, *cb1;
+
+	if (s == NULL ||
+	    (wp = window_pane_find_by_id(cp->pane)) == NULL ||
+	    winlink_find_by_window(&s->windows, wp->window) == NULL) {
+		TAILQ_FOREACH_SAFE(cb, &cp->blocks, entry, cb1)
+			control_free_block(cs, cb);
+		control_flush_all_blocks(c);
+		return (0);
+	}
+
+	while (used != limit && !TAILQ_EMPTY(&cp->blocks)) {
+		cb = TAILQ_FIRST(&cp->blocks);
+		log_debug("%s: %s: output block %zu for %%%u (used %zu/%zu)",
+		    __func__, c->name, cb->size, cp->pane, used, limit);
+
+		size = cb->size;
+		if (size > limit - used)
+			size = limit - used;
+		used += size;
+
+		message = control_append_data(cp, message, wp, size);
+
+		cb->size -= size;
+		if (cb->size == 0) {
+			TAILQ_REMOVE(&cp->blocks, cb, entry);
+			control_free_block(cs, cb);
+
+			cb = TAILQ_FIRST(&cs->all_blocks);
+			if (cb != NULL && cb->size == 0) {
+				if (wp != NULL && message != NULL) {
+					control_write_data(c, message);
+					message = NULL;
+				}
+				control_flush_all_blocks(c);
+			}
+		}
+	}
+	if (message != NULL)
+		control_write_data(c, message);
+	return (!TAILQ_EMPTY(&cp->blocks));
+}
+
+/* Control client write callback. */
+static void
+control_write_callback(__unused struct bufferevent *bufev, void *data)
+{
+	struct client		*c = data;
+	struct control_state	*cs = c->control_state;
+	struct control_pane	*cp, *cp1;
+	struct evbuffer		*evb = cs->write_event->output;
+	size_t			 space, limit;
+
+	control_flush_all_blocks(c);
+
+	while (EVBUFFER_LENGTH(evb) < CONTROL_BUFFER_HIGH) {
+		if (cs->pending_count == 0)
+			break;
+		space = CONTROL_BUFFER_HIGH - EVBUFFER_LENGTH(evb);
+		log_debug("%s: %s: %zu bytes available, %u panes", __func__,
+		    c->name, space, cs->pending_count);
+
+		limit = (space / cs->pending_count / 3); /* 3 bytes for \xxx */
+		if (limit < CONTROL_WRITE_MINIMUM)
+			limit = CONTROL_WRITE_MINIMUM;
+
+		TAILQ_FOREACH_SAFE(cp, &cs->pending_list, pending_entry, cp1) {
+			if (EVBUFFER_LENGTH(evb) >= CONTROL_BUFFER_HIGH)
+				break;
+			if (control_write_pending(c, cp, limit))
+				continue;
+			TAILQ_REMOVE(&cs->pending_list, cp, pending_entry);
+			cp->pending_flag = 0;
+			cs->pending_count--;
+		}
+	}
+	if (EVBUFFER_LENGTH(evb) == 0)
+		bufferevent_disable(cs->write_event, EV_WRITE);
+}
+
 /* Initialize for control mode. */
 void
 control_start(struct client *c)
@@ -277,22 +544,43 @@ control_start(struct client *c)
 	setblocking(c->fd, 0);
 
 	cs = c->control_state = xcalloc(1, sizeof *cs);
-	RB_INIT(&cs->offsets);
+	RB_INIT(&cs->panes);
+	TAILQ_INIT(&cs->pending_list);
+	TAILQ_INIT(&cs->all_blocks);
 
-	cs->read_event = bufferevent_new(c->fd, control_read_callback, NULL,
-	    control_error_callback, c);
+	cs->read_event = bufferevent_new(c->fd, control_read_callback,
+	    control_write_callback, control_error_callback, c);
 	bufferevent_enable(cs->read_event, EV_READ);
 
 	if (c->flags & CLIENT_CONTROLCONTROL)
 		cs->write_event = cs->read_event;
 	else {
-		cs->write_event = bufferevent_new(c->out_fd, NULL, NULL,
-		    control_error_callback, c);
+		cs->write_event = bufferevent_new(c->out_fd, NULL,
+		    control_write_callback, control_error_callback, c);
 	}
-	bufferevent_enable(cs->write_event, EV_WRITE);
+	bufferevent_setwatermark(cs->write_event, EV_WRITE, CONTROL_BUFFER_LOW,
+	    0);
 
-	if (c->flags & CLIENT_CONTROLCONTROL)
-		control_write(c, "\033P1000p");
+	if (c->flags & CLIENT_CONTROLCONTROL) {
+		bufferevent_write(cs->write_event, "\033P1000p", 7);
+		bufferevent_enable(cs->write_event, EV_WRITE);
+	}
+}
+
+/* Flush all output for a client that is detaching. */
+void
+control_flush(struct client *c)
+{
+	struct control_state	*cs = c->control_state;
+	struct control_pane	*cp;
+	struct control_block	*cb, *cb1;
+
+	RB_FOREACH(cp, control_panes, &cs->panes) {
+		TAILQ_FOREACH_SAFE(cb, &cp->blocks, entry, cb1) {
+			TAILQ_REMOVE(&cp->blocks, cb, entry);
+			control_free_block(cs, cb);
+		}
+	}
 }
 
 /* Stop control mode. */
@@ -300,11 +588,15 @@ void
 control_stop(struct client *c)
 {
 	struct control_state	*cs = c->control_state;
+	struct control_block	*cb, *cb1;
 
 	if (~c->flags & CLIENT_CONTROLCONTROL)
 		bufferevent_free(cs->write_event);
 	bufferevent_free(cs->read_event);
 
-	control_free_offsets(c);
+	TAILQ_FOREACH_SAFE(cb, &cs->all_blocks, all_entry, cb1)
+		control_free_block(cs, cb);
+	control_reset_offsets(c);
+
 	free(cs);
 }