Changeset 42383 in vbox

Timestamp:

Jul 25, 2012 10:07:58 AM (12 years ago)

Author:

vboxsync

Message:

Main/VirtualBox+Machine: optimize reaction time on session changes by adapting the waiting timeout, and signal near session closing (which unfortunately cannot be done precisely, as the session link to the Machine needs to be removed before the session is actually closed, and this makes notifications impossible)

Location:

trunk/src/VBox/Main/src-server

Files:

• MachineImpl.cpp (modified) (1 diff)
• VirtualBoxImpl.cpp (modified) (5 diffs)

trunk/src/VBox/Main/src-server/MachineImpl.cpp

@@ -12212 +12212 @@
     }
 
+    /* signal the client watcher thread, because the client is going away */
+    mParent->updateClientWatcher();
+
     LogFlowThisFuncLeave();
     return S_OK;

trunk/src/VBox/Main/src-server/VirtualBoxImpl.cpp

@@ -107 +107 @@
 // static
 Bstr VirtualBox::sAPIVersion;
+
+#ifdef VBOX_WITH_SYS_V_IPC_SESSION_WATCHER
+/** Table for adaptive timeouts in the client watcher. The counter starts at
+ * the maximum value and decreases to 0. */
+static const RTMSINTERVAL s_updateAdaptTimeouts[] = { 500, 200, 100, 50, 20, 10, 5 };
+#endif
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -283 +289 @@
     // the following are data for the client watcher thread
     const UPDATEREQTYPE                 updateReq;
+#ifdef VBOX_WITH_SYS_V_IPC_SESSION_WATCHER
+    uint8_t                             updateAdaptCtr;
+#endif
     const RTTHREAD                      threadClientWatcher;
     typedef std::list<RTPROCESS> ProcessList;
@@ -516 +525 @@
 #elif defined(VBOX_WITH_SYS_V_IPC_SESSION_WATCHER)
         RTSemEventCreate(&unconst(m->updateReq));
+        ASMAtomicUoWriteU8(&m->updateAdaptCtr, 0);
 #else
 # error "Port me!"
@@ -2627 +2637 @@
     RTSemEventSignal(m->updateReq);
 #elif defined(VBOX_WITH_SYS_V_IPC_SESSION_WATCHER)
+    ASMAtomicUoWriteU8(&m->updateAdaptCtr, RT_ELEMENTS(s_updateAdaptTimeouts) - 1);
     RTSemEventSignal(m->updateReq);
 #else
@@ -4810 +4821 @@
             autoCaller.release();
 
-            int rc = RTSemEventWait(that->m->updateReq, 500);
+            /* determine wait timeout adaptively: after updating information
+             * relevant to the client watcher, check a few times more
+             * frequently. This ensures good reaction time when the signalling
+             * has to be done a bit before the actual change for technical
+             * reasons, and saves CPU cycles when no activities are expected. */
+            RTMSINTERVAL cMillies;
+            {
+                uint8_t uOld, uNew;
+                do
+                {
+                    uOld = ASMAtomicUoReadU8(&that->m->updateAdaptCtr);
+                    uNew = uOld ? uOld - 1 : uOld;
+                } while (!ASMAtomicCmpXchgU8(&that->m->updateAdaptCtr, uNew, uOld));
+                Assert(uOld <= RT_ELEMENTS(s_updateAdaptTimeouts) - 1);
+                cMillies = s_updateAdaptTimeouts[uOld];
+            }
+
+            int rc = RTSemEventWait(that->m->updateReq, cMillies);
 
             /*