Merge pull request #24369 from vespa-engine/jonmv/start-then-stop-mbus-server

Jonmv/start then stop mbus server

6 files changed, 30 insertions, 14 deletions

diff --git a/container-disc/src/main/java/com/yahoo/container/jdisc/ConfiguredApplication.java b/container-disc/src/main/java/com/yahoo/container/jdisc/ConfiguredApplication.java
index 7ea91726673..625bd87c2db 100644
--- a/container-disc/src/main/java/com/yahoo/container/jdisc/ConfiguredApplication.java
+++ b/container-disc/src/main/java/com/yahoo/container/jdisc/ConfiguredApplication.java
@@ -366,6 +366,12 @@ public final class ConfiguredApplication implements Application {
         synchronized (monitor) {
             Set<ServerProvider> serversToClose = createIdentityHashSet(startedServers);
             serversToClose.removeAll(currentServers);
+            for (ServerProvider server : currentServers) {
+                if ( ! startedServers.contains(server) && server.isMultiplexed()) {
+                    server.start();
+                    startedServers.add(server);
+                }
+            }
             if (serversToClose.size() > 0) {
                 log.info(String.format("Closing %d server instances", serversToClose.size()));
                 for (ServerProvider server : serversToClose) {
@@ -374,7 +380,7 @@ public final class ConfiguredApplication implements Application {
                 }
             }
             for (ServerProvider server : currentServers) {
-                if (!startedServers.contains(server)) {
+                if ( ! startedServers.contains(server)) {
                     server.start();
                     startedServers.add(server);
                 }
diff --git a/container-messagebus/src/main/java/com/yahoo/messagebus/jdisc/MbusServer.java b/container-messagebus/src/main/java/com/yahoo/messagebus/jdisc/MbusServer.java
index 8f21cb227d8..3cf3b4bf8b0 100644
--- a/container-messagebus/src/main/java/com/yahoo/messagebus/jdisc/MbusServer.java
+++ b/container-messagebus/src/main/java/com/yahoo/messagebus/jdisc/MbusServer.java
@@ -60,6 +60,11 @@ public final class MbusServer extends AbstractResource implements ServerProvider
     }
 
     @Override
+    public boolean isMultiplexed() {
+        return true;
+    }
+
+    @Override
     protected void destroy() {
         log.log(Level.FINE, "Destroying message bus server.");
         runState.set(State.STOPPED);
diff --git a/jdisc_core/abi-spec.json b/jdisc_core/abi-spec.json
index 5beb723465b..8171b416b0c 100644
--- a/jdisc_core/abi-spec.json
+++ b/jdisc_core/abi-spec.json
@@ -905,7 +905,8 @@
     ],
     "methods": [
       "public abstract void start()",
-      "public abstract void close()"
+      "public abstract void close()",
+      "public boolean isMultiplexed()"
     ],
     "fields": []
   }
diff --git a/jdisc_core/src/main/java/com/yahoo/jdisc/service/ServerProvider.java b/jdisc_core/src/main/java/com/yahoo/jdisc/service/ServerProvider.java
index ef72e643dae..ecdc30400f1 100644
--- a/jdisc_core/src/main/java/com/yahoo/jdisc/service/ServerProvider.java
+++ b/jdisc_core/src/main/java/com/yahoo/jdisc/service/ServerProvider.java
@@ -49,4 +49,12 @@ public interface ServerProvider extends SharedResource {
      * Application} shutdown code.</p>
      */
     void close();
+
+    /**
+     * Whether multiple instances of this can coexist, by means of a multiplexer on top of any exclusive resource.
+     * If this is true, new instances to replace old ones, during a graph generation switch, will be started before
+     * the obsolete ones are stopped; otherwise, the old will be stopped, and then the new ones started.
+     */
+    default boolean isMultiplexed() { return false; }
+
 }
diff --git a/messagebus/src/main/java/com/yahoo/messagebus/network/NetworkMultiplexer.java b/messagebus/src/main/java/com/yahoo/messagebus/network/NetworkMultiplexer.java
index d36579d5be1..959fff488b1 100644
--- a/messagebus/src/main/java/com/yahoo/messagebus/network/NetworkMultiplexer.java
+++ b/messagebus/src/main/java/com/yahoo/messagebus/network/NetworkMultiplexer.java
@@ -59,7 +59,7 @@ public class NetworkMultiplexer implements NetworkOwner {
                     net.registerSession(session);
             }
             else if (owners.contains(owner))
-                throw new IllegalArgumentException("Session '" + session + "' with owner '" + owner + "' already registered with this");
+                throw new IllegalArgumentException("Session '" + session + "' with owner '" + owner + "' already registered with " +  this);
 
             owners.push(owner);
             return owners;
@@ -68,12 +68,12 @@ public class NetworkMultiplexer implements NetworkOwner {
 
     public void unregisterSession(String session, NetworkOwner owner, boolean broadcast) {
         sessions.computeIfPresent(session, (name, owners) -> {
-            owners.remove(owner);
-            if (owners.isEmpty()) {
+            if (owners.size() == 1 && owners.contains(owner)) {
                 if (broadcast)
                     net.unregisterSession(session);
                 return null;
             }
+            owners.remove(owner);
             return owners;
         });
     }
@@ -103,7 +103,7 @@ public class NetworkMultiplexer implements NetworkOwner {
     /** Attach the network owner to this, allowing this to forward messages to it. */
     public void attach(NetworkOwner owner) {
         if (owners.contains(owner))
-            throw new IllegalArgumentException(owner + " is already attached to this");
+            throw new IllegalArgumentException(owner + " is already attached to " + this);
 
         owners.add(owner);
     }
@@ -111,7 +111,7 @@ public class NetworkMultiplexer implements NetworkOwner {
     /** Detach the network owner from this, no longer allowing messages to it, and shutting down this is ownerless. */
     public void detach(NetworkOwner owner) {
         if ( ! owners.remove(owner))
-            throw new IllegalArgumentException(owner + " not attached to this");
+            throw new IllegalArgumentException(owner + " not attached to " + this);
 
         destroyIfOwnerless();
     }
@@ -137,12 +137,7 @@ public class NetworkMultiplexer implements NetworkOwner {
 
     @Override
     public String toString() {
-        return "NetworkMultiplexer{" +
-               "net=" + net +
-               ", owners=" + owners +
-               ", sessions=" + sessions +
-               ", destructible=" + disowned +
-               '}';
+        return "network multiplexer with owners: " + owners + ", sessions: " + sessions + " and destructible: " + disowned.get();
     }
 
 }
\ No newline at end of file
diff --git a/messagebus/src/test/java/com/yahoo/messagebus/network/NetworkMultiplexerTest.java b/messagebus/src/test/java/com/yahoo/messagebus/network/NetworkMultiplexerTest.java
index 60da1b49d90..57ded9f750d 100644
--- a/messagebus/src/test/java/com/yahoo/messagebus/network/NetworkMultiplexerTest.java
+++ b/messagebus/src/test/java/com/yahoo/messagebus/network/NetworkMultiplexerTest.java
@@ -43,7 +43,8 @@ public class NetworkMultiplexerTest {
             fail("Illegal to register same session multiple times with the same owner");
         }
         catch (IllegalArgumentException expected) {
-            assertEquals("Session 's1' with owner 'mock owner' already registered with this", expected.getMessage());
+            assertEquals("Session 's1' with owner 'mock owner' already registered with network multiplexer with owners: [mock owner], sessions: {s1=[mock owner]} and destructible: false",
+                         expected.getMessage());
         }
         assertEquals(Set.of("s1"), net.registered);