Patch to MRI signal.c to prevent unnecessary sigprocmask syscalls

gistfile1.diff

--- signal.c.orig	2008-08-21 18:42:46.000000000 -0700
+++ signal.c	2008-08-21 18:55:42.000000000 -0700
@@ -23,6 +23,7 @@
 
 #if defined HAVE_SIGPROCMASK || defined HAVE_SIGSETMASK
 #define USE_TRAP_MASK 1
+static int restore_signals = 0;
 #else
 #define USE_TRAP_MASK 0
 #endif
@@ -687,9 +688,19 @@
 
 #if USE_TRAP_MASK
 # ifdef HAVE_SIGPROCMASK
+
 static sigset_t trap_last_mask;
+#define sigcmpset(a,b) ({ \
+    int __cnt = _SIGSET_NWORDS; \
+    int __ret = 0; \
+    while (--__cnt >= 0) if (a.__val[__cnt] != b.__val[__cnt]){ __ret = -1; break; } \
+    __ret; })
+
 # else
+
 static int trap_last_mask;
+#define sigcmpset(a,b) (a!=b)
+
 # endif
 #endif
 
@@ -841,14 +852,17 @@
 trap_ensure(arg)
     struct trap_arg *arg;
 {
-    /* enable interrupt */
+  /* enable interrupt */
+  if (sigcmpset(arg->mask, trap_last_mask) != 0) {
 #ifdef HAVE_SIGPROCMASK
     sigprocmask(SIG_SETMASK, &arg->mask, NULL);
 #else
     sigsetmask(arg->mask);
 #endif
     trap_last_mask = arg->mask;
-    return 0;
+    restore_signals = 1;
+  }
+  return 0;
 }
 #endif
 
@@ -856,11 +870,14 @@
 rb_trap_restore_mask()
 {
 #if USE_TRAP_MASK
+  if (restore_signals) {
 # ifdef HAVE_SIGPROCMASK
     sigprocmask(SIG_SETMASK, &trap_last_mask, NULL);
 # else
     sigsetmask(trap_last_mask);
 # endif
+    restore_signals = 0;
+  }
 #endif
 }