From 0f5a59b215fdeff23d2632de1dfe7a22bfcb9d82 Mon Sep 17 00:00:00 2001
From: Andy Wingo <wingo@pobox.com>
Date: Wed, 2 Nov 2016 21:29:22 +0100
Subject: [PATCH] try-mutex in terms of mutex-lock

* libguile/threads.c (scm_try_mutex): Just call scm_lock_mutex_timed
  with a zero timeout.
* module/ice-9/threads.scm (try-mutex): Likewise.
---
 libguile/threads.c       | 22 +++-------------------
 module/ice-9/threads.scm |  5 +++++
 2 files changed, 8 insertions(+), 19 deletions(-)

diff --git a/libguile/threads.c b/libguile/threads.c
index 43bd31310..022534808 100644
--- a/libguile/threads.c
+++ b/libguile/threads.c
@@ -1311,27 +1311,11 @@ scm_dynwind_lock_mutex (SCM mutex)
 				       SCM_F_WIND_EXPLICITLY);
 }
 
-SCM_DEFINE (scm_try_mutex, "try-mutex", 1, 0, 0,
-	    (SCM mutex),
-"Try to lock @var{mutex}. If the mutex is already locked by someone "
-"else, return @code{#f}.  Else lock the mutex and return @code{#t}. ")
-#define FUNC_NAME s_scm_try_mutex
+SCM
+scm_try_mutex (SCM mutex)
 {
-  SCM exception;
-  int ret = 0;
-  scm_t_timespec cwaittime, *waittime = NULL;
-
-  SCM_VALIDATE_MUTEX (1, mutex);
-
-  to_timespec (scm_from_int(0), &cwaittime);
-  waittime = &cwaittime;
-
-  exception = fat_mutex_lock (mutex, waittime, SCM_UNDEFINED, &ret);
-  if (!scm_is_false (exception))
-    scm_ithrow (SCM_CAR (exception), scm_list_1 (SCM_CDR (exception)), 1);
-  return ret ? SCM_BOOL_T : SCM_BOOL_F;
+  return scm_lock_mutex_timed (mutex, SCM_INUM0, SCM_UNDEFINED);
 }
-#undef FUNC_NAME
 
 /*** Fat condition variables */
 
diff --git a/module/ice-9/threads.scm b/module/ice-9/threads.scm
index 555143e70..119334b46 100644
--- a/module/ice-9/threads.scm
+++ b/module/ice-9/threads.scm
@@ -136,6 +136,11 @@ Once @var{thunk} or @var{handler} returns, the return value is made the
           (lp))))
     thread))
 
+(define* (try-mutex mutex)
+  "Try to lock @var{mutex}.  If the mutex is already locked, return
+@code{#f}.  Otherwise lock the mutex and return @code{#t}."
+  (lock-mutex mutex 0))
+
 
 
 ;;; Macros first, so that the procedures expand correctly.