Changeset 37316 in vbox for trunk/include

Timestamp:

Jun 3, 2011 12:49:02 PM (14 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

72071

Message:

IPRT: Inlined the already-done check in RTOnce().

Location:

trunk/include/iprt

Files:

• mangling.h (modified) (1 diff)
• once.h (modified) (2 diffs)

trunk/include/iprt/mangling.h ¶

@@ -847 +847 @@
 # define RTNetTCPChecksum                               RT_MANGLER(RTNetTCPChecksum)
 # define RTNetUDPChecksum                               RT_MANGLER(RTNetUDPChecksum)
-# define RTOnce                                         RT_MANGLER(RTOnce)
+# define RTOnceSlow                                     RT_MANGLER(RTOnceSlow)
 # define RTOnceReset                                    RT_MANGLER(RTOnceReset)
 # define RTPathAbs                                      RT_MANGLER(RTPathAbs)

trunk/include/iprt/once.h ¶

@@ -29 +29 @@
 #include <iprt/cdefs.h>
 #include <iprt/types.h>
+#include <iprt/asm.h>
 #include <iprt/err.h>
 
@@ -120 +121 @@
  * @param   pvUser2         The second user parameter for pfnOnce.
  */
-RTDECL(int) RTOnce(PRTONCE pOnce, PFNRTONCE pfnOnce, void *pvUser1, void *pvUser2);
+RTDECL(int) RTOnceSlow(PRTONCE pOnce, PFNRTONCE pfnOnce, void *pvUser1, void *pvUser2);
+
+/**
+ * Serializes execution of the pfnOnce function, making sure it's
+ * executed exactly once and that nobody returns from RTOnce before
+ * it has executed successfully.
+ *
+ * @returns IPRT like status code returned by pfnOnce.
+ *
+ * @param   pOnce           Pointer to the execute once variable.
+ * @param   pfnOnce         The function to executed once.
+ * @param   pvUser1         The first user parameter for pfnOnce.
+ * @param   pvUser2         The second user parameter for pfnOnce.
+ */
+DECLINLINE(int) RTOnce(PRTONCE pOnce, PFNRTONCE pfnOnce, void *pvUser1, void *pvUser2)
+{
+    int32_t iState = ASMAtomicUoReadS32(&pOnce->iState);
+    if (RT_LIKELY(   iState == RTONCESTATE_DONE
+                  || iState == RTONCESTATE_DONE_CREATING_SEM
+                  || iState == RTONCESTATE_DONE_HAVE_SEM ))
+        return ASMAtomicUoReadS32(&pOnce->rc);
+    return RTOnceSlow(pOnce, pfnOnce, pvUser1, pvUser2);
+}
 
 /**