From 7301d0a8be9b5eb83d80198d589ca708e395c4fd Mon Sep 17 00:00:00 2001
From: Petr Baudis <pasky@ucw.cz>
Date: Sun, 17 Jan 2010 01:03:15 +0100
Subject: [PATCH] uct_playouts_threaded(): Also check for won situation here
 inst. of uct_playouts()

Now, uct_playouts() will never voluntarily terminate.
---
 uct/uct.c  | 23 +++++++++++++++++------
 uct/walk.c |  7 -------
 2 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/uct/uct.c b/uct/uct.c
index ece322a..1c888a0 100644
--- a/uct/uct.c
+++ b/uct/uct.c
@@ -265,7 +265,16 @@ uct_done(struct engine *e)
  * ...
  * workerK
  *             uct_playouts() loop, doing descend-playout until uct_halt
- */
+ *
+ * Another way to look at it is by functions (lines denote thread boundaries):
+ *
+ * | uct_genmove()
+ * | uct_playouts_threaded()
+ * | -----------------------
+ * | spawn_thread_manager()
+ * | -----------------------
+ * | spawn_worker()
+ * V uct_playouts() */
 
 /* Set in thread manager in case the workers should stop. */
 volatile sig_atomic_t uct_halt = 0;
@@ -365,9 +374,6 @@ spawn_thread_manager(void *ctx_)
 		free(ctx);
 		if (UDEBUGL(2))
 			fprintf(stderr, "Joined worker %d\n", finish_thread);
-		/* Do not get stalled by slow threads. */
-		if (joined >= u->threads / 2)
-			uct_halt = 1;
 		pthread_mutex_unlock(&finish_serializer);
 	}
 
@@ -433,14 +439,19 @@ uct_playouts_threaded(struct uct *u, struct board *b, enum stone color, struct t
 	 * count. However, TM_ROOT just does not deserve any more extra code
 	 * right now. */
 
-	/* We periodically poll the search tree and stop when we played enough
-	 * games. */
+	/* Now, just periodically poll the search tree. */
 	struct timespec busywait_interval = TREE_BUSYWAIT_INTERVAL;
 	while (1) {
 		nanosleep(&busywait_interval, NULL);
 
+		/* Did we play enough games? */
 		if (ctx->t->root->u.playouts - pgames > ngames)
 			break;
+		/* Won situation? */
+		struct tree_node *best = u->policy->choose(u->policy, ctx->t->root, b, color);
+		if (best && ((best->u.playouts >= 2000 && tree_node_get_value(ctx->t, 1, best->u.value) >= u->loss_threshold)
+			     || (best->u.playouts >= 500 && tree_node_get_value(ctx->t, 1, best->u.value) >= 0.95)))
+			break;
 	}
 
 	ctx = uct_search_stop();
diff --git a/uct/walk.c b/uct/walk.c
index c7ec5c1..4b9bdf3 100644
--- a/uct/walk.c
+++ b/uct/walk.c
@@ -352,13 +352,6 @@ uct_playouts(struct uct *u, struct board *b, enum stone color, struct tree *t)
 		if (unlikely(ok_to_talk && i > 0 && !(i % 10000))) {
 			uct_progress_status(u, t, color, i);
 		}
-
-		if (i > 0 && !(i % 500)) {
-			struct tree_node *best = u->policy->choose(u->policy, t->root, b, color);
-			if (best && ((best->u.playouts >= 2000 && tree_node_get_value(t, 1, best->u.value) >= u->loss_threshold)
-			             || (best->u.playouts >= 500 && tree_node_get_value(t, 1, best->u.value) >= 0.95)))
-				break;
-		}
 	}
 
 	if (ok_to_talk) {
-- 
2.11.4.GIT