MonetDB: default - Reduce locking by using atomic operations.

[Sjoerd Mullender]

Changeset: 5495549c6c69 for MonetDB
URL: http://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=5495549c6c69
Modified Files:
        gdk/gdk_atoms.c
Branch: default
Log Message:

Reduce locking by using atomic operations.


diffs (119 lines):

diff --git a/gdk/gdk_atoms.c b/gdk/gdk_atoms.c
--- a/gdk/gdk_atoms.c
+++ b/gdk/gdk_atoms.c
@@ -1564,16 +1564,11 @@ strWrite(const char *a, stream *s, size_
  * BUNhead(b,p)/BUNtail(b,p) instantiate a value on-the-fly by looking
  * at the position p in BAT b.
  */
-oid    GDKoid, GDKflushed;
-/*
- * Init the shared array of oid bases.
- */
-int
-OIDinit(void)
-{
-       GDKflushed = GDKoid = 0;
-       return 0;
-}
+static volatile ATOMIC_TYPE GDKoid;
+#ifdef ATOMIC_LOCK
+static MT_Lock GDKoidLock MT_LOCK_INITIALIZER("GDKoidLock");
+#endif
+static oid GDKflushed;         /* protected by MT_system_lock */
 
 /*
  * Make up some new OID for a specified database, based on the current
@@ -1586,29 +1581,39 @@ OIDrand(void)
 }
 
 /*
+ * Init the shared array of oid bases.
+ */
+int
+OIDinit(void)
+{
+#ifdef NEED_MT_LOCK_INIT
+       ATOMIC_INIT(GDKoidLock, "GDKoidLock");
+#endif
+       GDKflushed = 0;
+       GDKoid = OIDrand();
+       return 0;
+}
+
+/*
  * Initialize the current OID number to be starting at 'o'.
  */
 oid
 OIDbase(oid o)
 {
-       MT_lock_set(&MT_system_lock, "OIDbase");
-       GDKoid = o;
-       MT_lock_unset(&MT_system_lock, "OIDbase");
+       ATOMIC_SET(GDKoid, (ATOMIC_TYPE) o, GDKoidLock, "OIDbase");
        return o;
 }
 
 static oid
 OIDseed(oid o)
 {
-       oid t, p = GDKoid;
+       oid t, p = ATOMIC_GET(GDKoid, GDKoidLock, "OIDseed");
 
-       MT_lock_set(&MT_system_lock, "OIDseed");
        t = OIDrand();
        if (o > t)
                t = o;
        if (p >= t)
                t = p;
-       MT_lock_unset(&MT_system_lock, "OIDseed");
        return t;
 }
 
@@ -1640,10 +1645,12 @@ int
 OIDwrite(stream *s)
 {
        int ret = 0;
+       ATOMIC_TYPE o;
 
        MT_lock_set(&MT_system_lock, "OIDwrite");
-       if (GDKoid) {
-               GDKflushed = GDKoid;
+       o = ATOMIC_GET(GDKoid, GDKoidLock, "OIDwrite");
+       if (o) {
+               GDKflushed = (oid) o;
                ATOMprint(TYPE_oid, &GDKflushed, s);
                if (mnstr_errnr(s) ||
                    mnstr_write(s, " ", 1, 1) <= 0)
@@ -1656,10 +1663,11 @@ OIDwrite(stream *s)
 int
 OIDdirty(void)
 {
-       if (GDKoid && GDKoid > GDKflushed) {
-               return TRUE;
-       }
-       return FALSE;
+       int ret;
+       MT_lock_set(&MT_system_lock, "OIDdirty");
+       ret = ATOMIC_GET(GDKoid, GDKoidLock, "OIDdirty") > GDKflushed;
+       MT_lock_unset(&MT_system_lock, "OIDdirty");
+       return ret;
 }
 
 /*
@@ -1668,15 +1676,7 @@ OIDdirty(void)
 oid
 OIDnew(oid inc)
 {
-       oid ret;
-
-       MT_lock_set(&MT_system_lock, "OIDnew");
-       if (!GDKoid)
-               GDKoid = OIDrand();
-       ret = GDKoid;
-       GDKoid += inc;
-       MT_lock_unset(&MT_system_lock, "OIDnew");
-       return ret;
+       return (oid) ATOMIC_ADD(GDKoid, (ATOMIC_TYPE) inc, GDKoidLock, 
"OIDnew");
 }
 
 /*
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