Add a ScriptEngineFactory bundle tracker (#3275)

* Add a ScriptEngineFactory bundle tracker

The `ScriptEngingeFactoryBundleTracker` tracks all bundles that provide `ScriptEngineFcatory` capabilities and sets a `ReadyMarker` if all of them are activated.

Signed-off-by: Jan N. Klug <github@klug.nrw>

bundles/org.openhab.core.automation.module.script/src/main/java/org/openhab/core/automation/module/script/internal/ScriptEngineFactoryBundleTracker.java

@@ -0,0 +1,156 @@
+/**
+ * Copyright (c) 2010-2022 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.core.automation.module.script.internal;
+
+import java.util.Dictionary;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.core.automation.module.script.ScriptEngineFactory;
+import org.openhab.core.service.ReadyMarker;
+import org.openhab.core.service.ReadyMarkerFilter;
+import org.openhab.core.service.ReadyService;
+import org.openhab.core.service.StartLevelService;
+import org.osgi.framework.Bundle;
+import org.osgi.framework.BundleContext;
+import org.osgi.framework.BundleEvent;
+import org.osgi.service.component.annotations.Activate;
+import org.osgi.service.component.annotations.Component;
+import org.osgi.service.component.annotations.Deactivate;
+import org.osgi.service.component.annotations.Reference;
+import org.osgi.util.tracker.BundleTracker;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * The {@link ScriptEngineFactoryBundleTracker} tracks bundles that provide {@link ScriptEngineFactory} and sets the
+ * {@link #READY_MARKER} when all registered bundles are active
+ *
+ * @author Jan N. Klug - Initial contribution
+ */
+@NonNullByDefault
+@Component(immediate = true)
+public class ScriptEngineFactoryBundleTracker extends BundleTracker<Bundle> implements ReadyService.ReadyTracker {
+    private static final int STATE_MASK = Bundle.INSTALLED | Bundle.RESOLVED | Bundle.ACTIVE | Bundle.STARTING
+            | Bundle.STOPPING | Bundle.UNINSTALLED;
+    public static final ReadyMarker READY_MARKER = new ReadyMarker("automation", "scriptEngineFactories");
+
+    private final Logger logger = LoggerFactory.getLogger(ScriptEngineFactoryBundleTracker.class);
+
+    private final ReadyService readyService;
+    private final StartLevelService startLevelService;
+
+    private final Map<String, Integer> bundles = new ConcurrentHashMap<>();
+    private boolean ready = false;
+
+    @Activate
+    public ScriptEngineFactoryBundleTracker(final @Reference ReadyService readyService,
+            final @Reference StartLevelService startLevelService, BundleContext bc) {
+        super(bc, STATE_MASK, null);
+        this.readyService = readyService;
+        this.startLevelService = startLevelService;
+
+        this.open();
+
+        readyService.registerTracker(this, new ReadyMarkerFilter().withType(StartLevelService.STARTLEVEL_MARKER_TYPE)
+                .withIdentifier(Integer.toString(StartLevelService.STARTLEVEL_OSGI)));
+    }
+
+    @Deactivate
+    public void deactivate() throws Exception {
+        this.close();
+        ready = false;
+    }
+
+    private boolean allBundlesActive() {
+        return bundles.values().stream().allMatch(i -> i == Bundle.ACTIVE);
+    }
+
+    @Override
+    public Bundle addingBundle(@NonNullByDefault({}) Bundle bundle, @Nullable BundleEvent event) {
+        String bsn = bundle.getSymbolicName();
+        int state = bundle.getState();
+        if (isScriptingBundle(bundle)) {
+            logger.debug("Added {}: {} ", bsn, stateToString(state));
+            bundles.put(bsn, state);
+        }
+        checkReady();
+
+        return bundle;
+    }
+
+    @Override
+    public void modifiedBundle(@NonNullByDefault({}) Bundle bundle, @Nullable BundleEvent event,
+            @NonNullByDefault({}) Bundle object) {
+        String bsn = bundle.getSymbolicName();
+        int state = bundle.getState();
+        if (isScriptingBundle(bundle)) {
+            logger.debug("Modified {}: {}", bsn, stateToString(state));
+            bundles.put(bsn, state);
+        }
+        checkReady();
+    }
+
+    @Override
+    public void removedBundle(@NonNullByDefault({}) Bundle bundle, @Nullable BundleEvent event,
+            @NonNullByDefault({}) Bundle object) {
+        String bsn = bundle.getSymbolicName();
+        if (isScriptingBundle(bundle)) {
+            logger.debug("Removed {}", bsn);
+            bundles.remove(bsn);
+        }
+        checkReady();
+    }
+
+    @Override
+    public void onReadyMarkerAdded(ReadyMarker readyMarker) {
+        checkReady();
+    }
+
+    @Override
+    public void onReadyMarkerRemoved(ReadyMarker readyMarker) {
+        ready = false;
+        readyService.unmarkReady(READY_MARKER);
+    }
+
+    private void checkReady() {
+        if (!ready && startLevelService.getStartLevel() > StartLevelService.STARTLEVEL_OSGI && allBundlesActive()) {
+            logger.info("All automation bundles ready.");
+            readyService.markReady(READY_MARKER);
+            ready = true;
+        } else if (ready && !allBundlesActive()) {
+            readyService.unmarkReady(READY_MARKER);
+            ready = false;
+        }
+    }
+
+    private String stateToString(int state) {
+        return switch (state) {
+            case Bundle.UNINSTALLED -> "UNINSTALLED";
+            case Bundle.INSTALLED -> "INSTALLED";
+            case Bundle.RESOLVED -> "RESOLVED";
+            case Bundle.STARTING -> "STARTING";
+            case Bundle.STOPPING -> "STOPPING";
+            case Bundle.ACTIVE -> "ACTIVE";
+            default -> "UNKNOWN";
+        };
+    }
+
+    private boolean isScriptingBundle(Bundle bundle) {
+        Dictionary<String, String> headers = bundle.getHeaders();
+        String provideCapability = headers.get("Provide-Capability");
+        return provideCapability != null && provideCapability.contains(ScriptEngineFactory.class.getName());
+    }
+}

bundles/org.openhab.core/src/main/java/org/openhab/core/service/StartLevelService.java

@@ -58,7 +58,7 @@ import org.slf4j.LoggerFactory;
  * 10 - OSGi application start level has been reached, i.e. bundles are activated.
  * 20 - Model entities (items, things, links, persist config) have been loaded, both from db as well as files.
  * 30 - Item states have been restored from persistence service, where applicable.
- * 40 - Rules are loaded and parsed, both from db as well as dsl and script files.
+ * 40 - Rules from db, dsl and script files are loaded and parsed, script engine factories are available.
  * 50 - Rule engine has executed all "system started" rules and is active.
  * 70 - User interface is up and running.
  * 80 - All things have been initialized.