1 files changed, 90 insertions, 0 deletions
diff --git a/vespajlib/src/main/java/com/yahoo/concurrent/maintenance/JobControl.java b/vespajlib/src/main/java/com/yahoo/concurrent/maintenance/JobControl.java
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+++ b/vespajlib/src/main/java/com/yahoo/concurrent/maintenance/JobControl.java
@@ -0,0 +1,90 @@
+// Copyright Verizon Media. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.concurrent.maintenance;
+
+import com.yahoo.transaction.Mutex;
+
+import java.util.Collections;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentSkipListMap;
+
+/**
+ * Provides status and control over running maintenance jobs.
+ *
+ * This is multi-thread safe.
+ *
+ * @author bratseth
+ */
+public class JobControl {
+
+    /** This is not persisted as all nodes start all jobs */
+    private final Map<String, Maintainer> startedJobs = new ConcurrentSkipListMap<>();
+
+    /** Used to store deactivation in a persistent shared database to make changes take effect on all nodes */
+    private final Db db;
+
+    public JobControl(Db db) {
+        this.db = db;
+    }
+
+    /** Notifies this that a job was started */
+    public void started(String jobSimpleClassName, Maintainer maintainer) {
+        startedJobs.put(jobSimpleClassName, maintainer);
+    }
+
+    /**
+     * Returns a snapshot of the set of jobs started on this system (whether deactivated or not).
+     * Each job is represented by its simple (omitting package) class name.
+     */
+    public Set<String> jobs() { return Collections.unmodifiableSet(startedJobs.keySet()); }
+
+    /** Returns a snapshot containing the currently inactive jobs in this */
+    public Set<String> inactiveJobs() { return db.readInactiveJobs(); }
+
+    /** Returns true if this job is not currently deactivated */
+    public boolean isActive(String jobSimpleClassName) {
+        return  ! inactiveJobs().contains(jobSimpleClassName);
+    }
+
+    /** Set a job active or inactive */
+    public void setActive(String jobSimpleClassName, boolean active) {
+        try (var lock = db.lockInactiveJobs()) {
+            Set<String> inactiveJobs = db.readInactiveJobs();
+            if (active)
+                inactiveJobs.remove(jobSimpleClassName);
+            else
+                inactiveJobs.add(jobSimpleClassName);
+            db.writeInactiveJobs(inactiveJobs);
+        }
+    }
+
+    /** Run given job (inactive or not) immediately */
+    public void run(String jobSimpleClassName) {
+        var job = startedJobs.get(jobSimpleClassName);
+        if (job == null) throw new IllegalArgumentException("No such job '" + jobSimpleClassName + "'");
+        job.lockAndMaintain();
+    }
+
+    /** Acquire lock for running given job */
+    public Mutex lockJob(String jobSimpleClassName) {
+        return db.lockMaintenanceJob(jobSimpleClassName);
+    }
+
+    /** The database used for managing job state and synchronization */
+    public interface Db {
+
+        /** Returns the set of jobs that are temporarily inactive */
+        Set<String> readInactiveJobs();
+
+        /** Make given jobs as inactive */
+        void writeInactiveJobs(Set<String> inactiveJobs);
+
+        /** Acquire lock for changing jobs */
+        Mutex lockInactiveJobs();
+
+        /** Acquire lock for running given job */
+        Mutex lockMaintenanceJob(String job);
+
+    }
+
+}