conversations-classic/src/main/java/eu/siacs/conversations/utils/SerialSingleThreadExecutor.java

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package eu.siacs.conversations.utils;
import android.os.Looper;
import android.util.Log;
import java.util.ArrayDeque;
import java.util.Queue;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import eu.siacs.conversations.Config;
import eu.siacs.conversations.services.AttachFileToConversationRunnable;
public class SerialSingleThreadExecutor implements Executor {
private final Executor executor = Executors.newSingleThreadExecutor();
final ArrayDeque<Runnable> tasks = new ArrayDeque<>();
protected Runnable active;
private final String name;
public SerialSingleThreadExecutor(String name) {
this(name, false);
}
SerialSingleThreadExecutor(String name, boolean prepareLooper) {
if (prepareLooper) {
execute(Looper::prepare);
}
this.name = name;
}
public synchronized void execute(final Runnable r) {
tasks.offer(new Runner(r));
if (active == null) {
scheduleNext();
}
}
private synchronized void scheduleNext() {
if ((active = tasks.poll()) != null) {
executor.execute(active);
int remaining = tasks.size();
if (remaining > 0) {
Log.d(Config.LOGTAG,remaining+" remaining tasks on executor '"+name+"'");
}
}
}
private class Runner implements Runnable, Cancellable {
private final Runnable runnable;
private Runner(Runnable runnable) {
this.runnable = runnable;
}
@Override
public void cancel() {
if (runnable instanceof Cancellable) {
((Cancellable) runnable).cancel();
}
}
@Override
public void run() {
try {
runnable.run();
} finally {
scheduleNext();
}
}
}
}