From a9afd1efef60470e2eeadc29b59d949abbecc6ca Mon Sep 17 00:00:00 2001
From: Markus Armbruster <armbru@pond.sub.org>
Date: Fri, 20 Jul 2007 19:09:34 +0000
Subject: [PATCH] (update_lock, play_lock, update_pending, play_wrlock_wanted):
 Move to main.c and rename to better reflect their purpose.  Fix misleading
 comments.

---
 include/server.h          |  9 +++++----
 src/lib/gen/io.c          |  4 ++--
 src/lib/player/dispatch.c |  4 ++--
 src/server/main.c         | 15 ++++++++++++++-
 src/server/update.c       | 28 ++++++++--------------------
 5 files changed, 31 insertions(+), 29 deletions(-)

diff --git a/include/server.h b/include/server.h
index 15908b44..413a95eb 100644
--- a/include/server.h
+++ b/include/server.h
@@ -36,11 +36,12 @@
 
 #include "empthread.h"
 
-extern int shutdown_pending;
-extern int update_pending;
-extern int update_running;
-extern empth_rwlock_t *update_lock;
 #define UPDATE_TIME_LEN 16
+
+extern int shutdown_pending;
+extern empth_rwlock_t *play_lock;
+extern int play_wrlock_wanted;
+extern int update_running;
 extern time_t update_time[UPDATE_TIME_LEN];
 
 void market_init(void);
diff --git a/src/lib/gen/io.c b/src/lib/gen/io.c
index 7d87c330..8744df63 100644
--- a/src/lib/gen/io.c
+++ b/src/lib/gen/io.c
@@ -324,9 +324,9 @@ io_output_all(struct iop *iop)
      * Mustn't block a player thread while update is pending, or else
      * a malicous player could delay the update indefinitely
      */
-    while (((n = io_output(iop, IO_NOWAIT)) > 0) && !update_pending) {
+    while ((n = io_output(iop, IO_NOWAIT)) > 0 && !play_wrlock_wanted)
 	empth_select(iop->fd, EMPTH_FD_WRITE);
-    }
+
     return n;
 }
 
diff --git a/src/lib/player/dispatch.c b/src/lib/player/dispatch.c
index c1d9182e..22117f16 100644
--- a/src/lib/player/dispatch.c
+++ b/src/lib/player/dispatch.c
@@ -88,7 +88,7 @@ dispatch(char *buf, char *redir)
 	pr("Command not implemented\n");
 	return 0;
     }
-    empth_rwlock_rdlock(update_lock);
+    empth_rwlock_rdlock(play_lock);
     if (redir) {
 	prredir(redir);
 	uprnf(buf);
@@ -110,7 +110,7 @@ dispatch(char *buf, char *redir)
 	logerror("%s: returned bad value", command->c_form);
 	break;
     }
-    empth_rwlock_unlock(update_lock);
+    empth_rwlock_unlock(play_lock);
     player->command = 0;
     return 0;
 }
diff --git a/src/server/main.c b/src/server/main.c
index 637dbe4d..183b04d5 100644
--- a/src/server/main.c
+++ b/src/server/main.c
@@ -78,6 +78,19 @@ static void loc_NTInit(void);
 static void loc_NTTerm(void);
 #endif
 
+/*
+ * Lock to synchronize player threads with update and shutdown.
+ * Update and shutdown takes it exclusive, commands take it shared.
+ */
+empth_rwlock_t *play_lock;
+
+/*
+ * Is a thread attempting to take an exclusive play_lock?
+ * Threads holding a shared play_lock must not sleep while this is
+ * true.
+ */
+int play_wrlock_wanted;
+
 static char pidfname[] = "server.pid";
 
 /* Run as daemon?  If yes, detach from controlling terminal etc. */
@@ -373,7 +386,7 @@ shutdwn(int sig)
 	}
 	empth_wakeup(p->proc);
     }
-    empth_rwlock_wrlock(update_lock);
+    empth_rwlock_wrlock(play_lock);
     /* rely on player_kill_idle() for killing hung player threads */
     if (sig)
 	logerror("Server shutting down on signal %d", sig);
diff --git a/src/server/update.c b/src/server/update.c
index 2704cad1..1240cc31 100644
--- a/src/server/update.c
+++ b/src/server/update.c
@@ -48,18 +48,6 @@
 #include "prototypes.h"
 #include "server.h"
 
-/*
- * Lock to synchronize player threads with the update.
- * Update takes it exclusive, commands take it shared.
- */
-empth_rwlock_t *update_lock;
-
-/*
- * Update is pending, player threads must give up update_lock ASAP.
- * This means they must not block while update_pending.
- */
-int update_pending;
-
 /*
  * Update is running.
  * Can be used to suppress messages, or direct them to bulletins.
@@ -86,8 +74,8 @@ update_init(void)
     if (update_get_schedule() < 0)
 	exit(1);
 
-    update_lock = empth_rwlock_create("Update");
-    if (!update_lock)
+    play_lock = empth_rwlock_create("Update");
+    if (!play_lock)
 	exit_nomem();
 
     dp = player_new(-1);
@@ -205,7 +193,7 @@ update_run(void)
 {
     struct player *p;
 
-    update_pending = 1;
+    play_wrlock_wanted = 1;
     for (p = player_next(0); p != 0; p = player_next(p)) {
 	if (p->state != PS_PLAYING)
 	    continue;
@@ -215,18 +203,18 @@ update_run(void)
 	    empth_wakeup(p->proc);
 	}
     }
-    empth_rwlock_wrlock(update_lock);
+    empth_rwlock_wrlock(play_lock);
     if (*pre_update_hook) {
 	if (run_hook(pre_update_hook, "pre-update")) {
-	    update_pending = 0;
-	    empth_rwlock_unlock(update_lock);
+	    play_wrlock_wanted = 0;
+	    empth_rwlock_unlock(play_lock);
 	    return;
 	}
     }
     update_running = 1;
     update_main();
-    update_pending = update_running = 0;
-    empth_rwlock_unlock(update_lock);
+    play_wrlock_wanted = update_running = 0;
+    empth_rwlock_unlock(play_lock);
 }
 
 static int