Fix missing Scheduler

android/src/main/java/org/strongswan/android/logic/Scheduler.java

@@ -0,0 +1,169 @@
+/*
+ * Copyright (C) 2020 Tobias Brunner
+ * HSR Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+package org.strongswan.android.logic;
+
+import android.app.AlarmManager;
+import android.app.PendingIntent;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.os.Build;
+
+import java.util.ArrayList;
+import java.util.PriorityQueue;
+import java.util.UUID;
+
+import androidx.annotation.RequiresApi;
+
+public class Scheduler extends BroadcastReceiver
+{
+	private final String EXECUTE_JOB = "org.strongswan.android.Scheduler.EXECUTE_JOB";
+	private final Context mContext;
+	private final AlarmManager mManager;
+	private final PriorityQueue<ScheduledJob> mJobs;
+
+	public Scheduler(Context context)
+	{
+		mContext = context;
+		mManager = (AlarmManager)context.getSystemService(Context.ALARM_SERVICE);
+		mJobs = new PriorityQueue<>();
+
+		IntentFilter filter = new IntentFilter();
+		filter.addAction(EXECUTE_JOB);
+		mContext.registerReceiver(this, filter);
+	}
+
+	/**
+	 * Remove all pending jobs and unregister the receiver.
+	 * Called via JNI.
+	 */
+	public void Terminate()
+	{
+		synchronized (this)
+		{
+			mJobs.clear();
+		}
+		mManager.cancel(createIntent());
+		mContext.unregisterReceiver(this);
+	}
+
+	/**
+	 * Allocate a job ID. Called via JNI.
+	 *
+	 * @return random ID for a new job
+	 */
+	public String allocateId()
+	{
+		return UUID.randomUUID().toString();
+	}
+
+	/**
+	 * Create a pending intent to execute a job.
+	 *
+	 * @return pending intent
+	 */
+	private PendingIntent createIntent()
+	{
+		/* using component/class doesn't work with dynamic broadcast receivers */
+		Intent intent = new Intent(EXECUTE_JOB);
+		intent.setPackage(mContext.getPackageName());
+		return PendingIntent.getBroadcast(mContext, 0, intent, 0);
+	}
+
+	/**
+	 * Schedule executing a job in the future.
+	 * Called via JNI from different threads.
+	 *
+	 * @param id job ID
+	 * @param ms delta in milliseconds when the job should be executed
+	 */
+	@RequiresApi(api = Build.VERSION_CODES.M)
+	public void scheduleJob(String id, long ms)
+	{
+		synchronized (this)
+		{
+			ScheduledJob job = new ScheduledJob(id, System.currentTimeMillis() + ms);
+			mJobs.add(job);
+
+			if (job == mJobs.peek())
+			{	/* update the alarm if the job has to be executed before all others */
+				PendingIntent pending = createIntent();
+				mManager.setExactAndAllowWhileIdle(AlarmManager.RTC_WAKEUP, job.Time, pending);
+			}
+		}
+	}
+
+	@RequiresApi(api = Build.VERSION_CODES.M)
+	@Override
+	public void onReceive(Context context, Intent intent)
+	{
+		ArrayList<ScheduledJob> jobs = new ArrayList<>();
+		long now = System.currentTimeMillis();
+
+		synchronized (this)
+		{
+			ScheduledJob job = mJobs.peek();
+			while (job != null)
+			{
+				if (job.Time > now)
+				{
+					break;
+				}
+				jobs.add(mJobs.remove());
+				job = mJobs.peek();
+			}
+			if (job != null)
+			{
+				PendingIntent pending = createIntent();
+				mManager.setExactAndAllowWhileIdle(AlarmManager.RTC_WAKEUP, job.Time, pending);
+			}
+		}
+
+		for (ScheduledJob job : jobs)
+		{
+			executeJob(job.Id);
+		}
+	}
+
+	/**
+	 * Execute the job with the given ID.
+	 *
+	 * @param id job ID
+	 */
+	public native void executeJob(String id);
+
+	/**
+	 * Keep track of scheduled jobs.
+	 */
+	private static class ScheduledJob implements Comparable<ScheduledJob>
+	{
+		String Id;
+		long Time;
+
+		ScheduledJob(String id, long time)
+		{
+			Id = id;
+			Time = time;
+		}
+
+		@Override
+		public int compareTo(ScheduledJob o)
+		{
+			return Long.compare(Time, o.Time);
+		}
+	}
+}