commit 7e2c935920cafadbd87c351f1a3239932864fb90
Author: Fredrik Höglund <fredrik@kde.org>
Date:   Fri May 18 20:06:14 2007 +0200

    Add a new IDLETIME system sync counter.
    
    This counter exposes the time in milliseconds since the last
    input event. Clients such as screen savers and power managers
    can set an alarm on this counter to find out when the idle time
    reaches a certain value, without having to poll the server.

diff --git a/Xext/sync.c b/Xext/sync.c
index c5441a1..6fc2dcc 100644
--- a/Xext/sync.c
+++ b/Xext/sync.c
@@ -243,6 +243,11 @@ SyncInitServerTime(
     void
 );
 
+static void
+SyncInitIdleTime(
+    void
+);
+
 static void 
 SyncResetProc(
     ExtensionEntry * /* extEntry */
@@ -2400,6 +2405,7 @@ SyncExtensionInit(INITARGS)
      * because there is always a servertime counter.
      */
     SyncInitServerTime();
+    SyncInitIdleTime();
 
 #ifdef DEBUG
     fprintf(stderr, "Sync Extension %d.%d\n",
@@ -2520,3 +2526,116 @@ SyncInitServerTime(void)
 			    ServertimeQueryValue, ServertimeBracketValues);
     pnext_time = NULL;
 }
+
+
+
+/*
+ * IDLETIME implementation
+ */
+
+static pointer IdleTimeCounter;
+static XSyncValue *pIdleTimeValueLess;
+static XSyncValue *pIdleTimeValueGreater;
+
+static void
+IdleTimeQueryValue (pointer pCounter, CARD64 *pValue_return)
+{
+    CARD32 idle = GetTimeInMillis() - lastDeviceEventTime.milliseconds;
+    XSyncIntsToValue (pValue_return, idle, 0);
+}
+
+static void
+IdleTimeBlockHandler (pointer env,
+                      struct timeval **wt,
+                      pointer LastSelectMask)
+{
+    XSyncValue idle;
+
+    if (!pIdleTimeValueLess && !pIdleTimeValueGreater)
+	return;
+
+    IdleTimeQueryValue (NULL, &idle);
+
+    if (pIdleTimeValueLess &&
+        XSyncValueLessOrEqual (idle, *pIdleTimeValueLess))
+    {
+	AdjustWaitForDelay (wt, 0);
+    }
+    else if (pIdleTimeValueGreater)
+    {
+	unsigned long timeout = 0;
+
+	if (XSyncValueLessThan (idle, *pIdleTimeValueGreater))
+	{
+	    XSyncValue value;
+	    Bool overflow;
+
+	    XSyncValueSubtract (&value, *pIdleTimeValueGreater,
+	                        idle, &overflow);
+	    timeout = XSyncValueLow32 (value);
+	}
+
+	AdjustWaitForDelay (wt, timeout);
+    }
+}
+
+static void
+IdleTimeWakeupHandler (pointer env,
+                       int rc,
+                       pointer LastSelectMask)
+{
+    XSyncValue idle;
+
+    if (!pIdleTimeValueLess && !pIdleTimeValueGreater)
+	return;
+
+    IdleTimeQueryValue (NULL, &idle);
+
+    if ((pIdleTimeValueGreater &&
+         XSyncValueGreaterThan (idle, *pIdleTimeValueGreater)) ||
+        (pIdleTimeValueLess && XSyncValueLessThan (idle, *pIdleTimeValueLess)))
+    {
+	SyncChangeCounter (IdleTimeCounter, idle);
+    }
+}
+
+static void
+IdleTimeBracketValues (pointer pCounter,
+                       CARD64 *pbracket_less,
+                       CARD64 *pbracket_greater)
+{
+    Bool registered = (pIdleTimeValueLess || pIdleTimeValueGreater);
+
+    if (registered && !pbracket_less && !pbracket_greater)
+    {
+	RemoveBlockAndWakeupHandlers(IdleTimeBlockHandler,
+	                             IdleTimeWakeupHandler,
+	                             NULL);
+    }
+    else if (!registered && (pbracket_less || pbracket_greater))
+    {
+	RegisterBlockAndWakeupHandlers(IdleTimeBlockHandler,
+	                               IdleTimeWakeupHandler,
+	                               NULL);
+    }
+
+    pIdleTimeValueGreater = pbracket_greater;
+    pIdleTimeValueLess    = pbracket_less;
+}
+
+static void
+SyncInitIdleTime (void)
+{
+    CARD64 resolution;
+    XSyncValue idle;
+
+    IdleTimeQueryValue (NULL, &idle);
+    XSyncIntToValue (&resolution, 4);
+
+    IdleTimeCounter = SyncCreateSystemCounter ("IDLETIME", idle, resolution,
+                                               XSyncCounterUnrestricted,
+                                               IdleTimeQueryValue,
+                                               IdleTimeBracketValues);
+
+    pIdleTimeValueLess = pIdleTimeValueGreater = NULL;
+}