Re: [libvirt] [libvirt-java] [PATCH 39/65] Introduce event loop support

At Fri, 21 Feb 2014 11:03:49 +0000, Daniel P. Berrange wrote: This is what I'd want to squash in prior pushing the patch in order to avoid failures due to virEventAddTimeout when stopping an event loop as suggested by you, Eric[1] and Jim[2]. Since this code requires the virEventUpdateTimeout function, I've added it into patch 36/65 as you requested[3]. [1]: http://www.redhat.com/archives/libvir-list/2014-March/msg00144.html [2]: http://www.redhat.com/archives/libvir-list/2014-March/msg00168.html [3]: http://www.redhat.com/archives/libvir-list/2014-February/msg01318.html --- diff --git a/src/main/java/org/libvirt/Library.java b/src/main/java/org/libvirt/Library.java --- a/src/main/java/org/libvirt/Library.java +++ b/src/main/java/org/libvirt/Library.java @@ -1,6 +1,7 @@ package org.libvirt; import org.libvirt.jna.Libvirt; +import org.libvirt.jna.Libvirt.VirEventTimeoutCallback; import static org.libvirt.ErrorHandler.processError; import com.sun.jna.Native; @@ -8,6 +9,7 @@ import com.sun.jna.ptr.PointerByReference; import java.util.concurrent.atomic.AtomicBoolean; +import java.util.concurrent.atomic.AtomicInteger; /** * This class represents an instance of the JNA mapped libvirt @@ -20,6 +22,14 @@ */ final class Library { private static AtomicBoolean runLoop = new AtomicBoolean(); + private static AtomicInteger timerID = new AtomicInteger(-1); + private static VirEventTimeoutCallback timer = new VirEventTimeoutCallback() { + @Override + public void tick(int id, Pointer p) { + // disable myself again right after being triggered + libvirt.virEventUpdateTimeout(id, -1); + } + }; final static Libvirt libvirt; @@ -109,7 +119,18 @@ * @see #runLoop */ public static void initEventLoop() throws LibvirtException { - processError(libvirt.virEventRegisterDefaultImpl()); + if (timerID.get() == -1) { + processError(libvirt.virEventRegisterDefaultImpl()); + + // add a disabled timer which is used later to break out + // of the event loop + int id = processError(libvirt.virEventAddTimeout(-1, timer, null, null)); + + // remove this timer when there already is another one + if (!timerID.compareAndSet(-1, id)) { + libvirt.virEventRemoveTimeout(id); + } + } } /** @@ -164,16 +185,10 @@ */ public static void stopEventLoop() throws LibvirtException { if (runLoop.getAndSet(false)) { - // add a timeout which fires immediately so that the processEvent - // method returns if it is waiting - libvirt.virEventAddTimeout(0, new org.libvirt.jna.Libvirt.VirEventTimeoutCallback() { - @Override - public void tick(int id, Pointer p) { - // remove itself right after it served its purpose - libvirt.virEventRemoveTimeout(id); - } - }, - null, null); + // fire the timer immediately + int timer = timerID.get(); + if (timer >= 0) + libvirt.virEventUpdateTimeout(timer, 0); } } }