From ddc4512d2e0eda6c705e002cb5dbf80719d709e1 Mon Sep 17 00:00:00 2001
From: nicm <nicm>
Date: Sun, 16 Oct 2016 17:55:14 +0000
Subject: Rewrite command queue handling. Each client still has a command
 queue, but there is also now a global command queue. Instead of command
 queues being dispatched on demand from wherever the command happens to be
 added, they are now all dispatched from the top level server loop. Command
 queues may now also include callbacks as well as commands, and items may be
 inserted after the current command as well as at the end.

This all makes command queues significantly more predictable and easier
to use, and avoids the complex multiple nested command queues used by
source-file, if-shell and friends.

A mass rename of struct cmdq to a better name (cmdq_item probably) is
coming.
---
 cmd-wait-for.c | 69 +++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 39 insertions(+), 30 deletions(-)

(limited to 'cmd-wait-for.c')

diff --git a/cmd-wait-for.c b/cmd-wait-for.c
index fb2fb699..505e4d63 100644
--- a/cmd-wait-for.c
+++ b/cmd-wait-for.c
@@ -41,13 +41,18 @@ const struct cmd_entry cmd_wait_for_entry = {
 	.exec = cmd_wait_for_exec
 };
 
+struct wait_item {
+	struct cmd_q		*cmdq;
+	TAILQ_ENTRY(wait_item)	 entry;
+};
+
 struct wait_channel {
 	const char	       *name;
 	int			locked;
 	int			woken;
 
-	TAILQ_HEAD(, cmd_q)	waiters;
-	TAILQ_HEAD(, cmd_q)	lockers;
+	TAILQ_HEAD(, wait_item)	waiters;
+	TAILQ_HEAD(, wait_item)	lockers;
 
 	RB_ENTRY(wait_channel)	entry;
 };
@@ -135,7 +140,7 @@ static enum cmd_retval
 cmd_wait_for_signal(__unused struct cmd_q *cmdq, const char *name,
     struct wait_channel *wc)
 {
-	struct cmd_q	*wq, *wq1;
+	struct wait_item	*wi, *wi1;
 
 	if (wc == NULL)
 		wc = cmd_wait_for_add(name);
@@ -147,10 +152,11 @@ cmd_wait_for_signal(__unused struct cmd_q *cmdq, const char *name,
 	}
 	log_debug("signal wait channel %s, with waiters", wc->name);
 
-	TAILQ_FOREACH_SAFE(wq, &wc->waiters, waitentry, wq1) {
-		TAILQ_REMOVE(&wc->waiters, wq, waitentry);
-		if (!cmdq_free(wq))
-			cmdq_continue(wq);
+	TAILQ_FOREACH_SAFE(wi, &wc->waiters, entry, wi1) {
+		wi->cmdq->flags &= ~CMD_Q_WAITING;
+
+		TAILQ_REMOVE(&wc->waiters, wi, entry);
+		free(wi);
 	}
 
 	cmd_wait_for_remove(wc);
@@ -158,10 +164,10 @@ cmd_wait_for_signal(__unused struct cmd_q *cmdq, const char *name,
 }
 
 static enum cmd_retval
-cmd_wait_for_wait(struct cmd_q *cmdq, const char *name,
-    struct wait_channel *wc)
+cmd_wait_for_wait(struct cmd_q *cmdq, const char *name, struct wait_channel *wc)
 {
-	struct client	*c = cmdq->client;
+	struct client		*c = cmdq->client;
+	struct wait_item	*wi;
 
 	if (c == NULL || c->session != NULL) {
 		cmdq_error(cmdq, "not able to wait");
@@ -178,16 +184,18 @@ cmd_wait_for_wait(struct cmd_q *cmdq, const char *name,
 	}
 	log_debug("wait channel %s not woken (%p)", wc->name, c);
 
-	TAILQ_INSERT_TAIL(&wc->waiters, cmdq, waitentry);
-	cmdq->references++;
+	wi = xcalloc(1, sizeof *wi);
+	wi->cmdq = cmdq;
+	TAILQ_INSERT_TAIL(&wc->waiters, wi, entry);
 
 	return (CMD_RETURN_WAIT);
 }
 
 static enum cmd_retval
-cmd_wait_for_lock(struct cmd_q *cmdq, const char *name,
-    struct wait_channel *wc)
+cmd_wait_for_lock(struct cmd_q *cmdq, const char *name, struct wait_channel *wc)
 {
+	struct wait_item	*wi;
+
 	if (cmdq->client == NULL || cmdq->client->session != NULL) {
 		cmdq_error(cmdq, "not able to lock");
 		return (CMD_RETURN_ERROR);
@@ -197,8 +205,9 @@ cmd_wait_for_lock(struct cmd_q *cmdq, const char *name,
 		wc = cmd_wait_for_add(name);
 
 	if (wc->locked) {
-		TAILQ_INSERT_TAIL(&wc->lockers, cmdq, waitentry);
-		cmdq->references++;
+		wi = xcalloc(1, sizeof *wi);
+		wi->cmdq = cmdq;
+		TAILQ_INSERT_TAIL(&wc->lockers, wi, entry);
 		return (CMD_RETURN_WAIT);
 	}
 	wc->locked = 1;
@@ -210,17 +219,17 @@ static enum cmd_retval
 cmd_wait_for_unlock(struct cmd_q *cmdq, const char *name,
     struct wait_channel *wc)
 {
-	struct cmd_q	*wq;
+	struct wait_item	*wi;
 
 	if (wc == NULL || !wc->locked) {
 		cmdq_error(cmdq, "channel %s not locked", name);
 		return (CMD_RETURN_ERROR);
 	}
 
-	if ((wq = TAILQ_FIRST(&wc->lockers)) != NULL) {
-		TAILQ_REMOVE(&wc->lockers, wq, waitentry);
-		if (!cmdq_free(wq))
-			cmdq_continue(wq);
+	if ((wi = TAILQ_FIRST(&wc->lockers)) != NULL) {
+		wi->cmdq->flags &= ~CMD_Q_WAITING;
+		TAILQ_REMOVE(&wc->lockers, wi, entry);
+		free(wi);
 	} else {
 		wc->locked = 0;
 		cmd_wait_for_remove(wc);
@@ -233,19 +242,19 @@ void
 cmd_wait_for_flush(void)
 {
 	struct wait_channel	*wc, *wc1;
-	struct cmd_q		*wq, *wq1;
+	struct wait_item	*wi, *wi1;
 
 	RB_FOREACH_SAFE(wc, wait_channels, &wait_channels, wc1) {
-		TAILQ_FOREACH_SAFE(wq, &wc->waiters, waitentry, wq1) {
-			TAILQ_REMOVE(&wc->waiters, wq, waitentry);
-			if (!cmdq_free(wq))
-				cmdq_continue(wq);
+		TAILQ_FOREACH_SAFE(wi, &wc->waiters, entry, wi1) {
+			wi->cmdq->flags &= ~CMD_Q_WAITING;
+			TAILQ_REMOVE(&wc->waiters, wi, entry);
+			free(wi);
 		}
 		wc->woken = 1;
-		TAILQ_FOREACH_SAFE(wq, &wc->lockers, waitentry, wq1) {
-			TAILQ_REMOVE(&wc->lockers, wq, waitentry);
-			if (!cmdq_free(wq))
-				cmdq_continue(wq);
+		TAILQ_FOREACH_SAFE(wi, &wc->lockers, entry, wi1) {
+			wi->cmdq->flags &= ~CMD_Q_WAITING;
+			TAILQ_REMOVE(&wc->lockers, wi, entry);
+			free(wi);
 		}
 		wc->locked = 0;
 		cmd_wait_for_remove(wc);
-- 
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