4 files changed, 316 insertions, 0 deletions
diff --git a/src/main/java/io/trygvis/async/AsyncService.java b/src/main/java/io/trygvis/async/AsyncService.java
new file mode 100755
index 0000000..e90a0e4
--- /dev/null
+++ b/src/main/java/io/trygvis/async/AsyncService.java
@@ -0,0 +1,37 @@
+package io.trygvis.async;
+
+import io.trygvis.queue.Queue;
+import io.trygvis.queue.Task;
+import org.quartz.SchedulerException;
+
+import java.util.List;
+
+/**
+ * A simple framework for running tasks.
+ */
+public interface AsyncService {
+
+    /**
+     * @param name
+     * @param interval how often the queue should be polled for missed tasks in seconds.
+     * @param callable
+     * @return
+     * @throws SchedulerException
+     */
+    Queue registerQueue(String name, int interval, AsyncCallable callable) throws SchedulerException;
+
+    Queue getQueue(String name);
+
+    Task schedule(Queue queue, String... args);
+
+    Task schedule(long parent, Queue queue, String... args);
+
+    /**
+     * Polls for a new state of the execution.
+     */
+    Task update(Task ref);
+
+    interface AsyncCallable {
+        void run(List<String> arguments) throws Exception;
+    }
+}
diff --git a/src/main/java/io/trygvis/async/JdbcAsyncService.java b/src/main/java/io/trygvis/async/JdbcAsyncService.java
new file mode 100644
index 0000000..4e78a37
--- /dev/null
+++ b/src/main/java/io/trygvis/async/JdbcAsyncService.java
@@ -0,0 +1,153 @@
+package io.trygvis.async;
+
+import io.trygvis.queue.Queue;
+import io.trygvis.queue.QueueDao;
+import io.trygvis.queue.Task;
+import io.trygvis.queue.TaskDao;
+import org.quartz.SchedulerException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+import org.springframework.transaction.annotation.Transactional;
+import org.springframework.transaction.support.TransactionSynchronization;
+import org.springframework.transaction.support.TransactionSynchronizationAdapter;
+import org.springframework.transaction.support.TransactionTemplate;
+
+import java.util.Date;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledThreadPoolExecutor;
+
+import static java.lang.System.currentTimeMillis;
+import static java.lang.Thread.sleep;
+import static java.util.Arrays.asList;
+import static java.util.concurrent.TimeUnit.SECONDS;
+import static org.springframework.transaction.annotation.Propagation.REQUIRED;
+import static org.springframework.transaction.support.TransactionSynchronizationManager.registerSynchronization;
+
+@Component
+public class JdbcAsyncService implements AsyncService {
+    private final Logger log = LoggerFactory.getLogger(getClass());
+
+    private final ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(10, Executors.defaultThreadFactory());
+
+    private final Map<String, QueueThread> queues = new HashMap<>();
+
+    @Autowired
+    private TransactionTemplate transactionTemplate;
+
+    @Autowired
+    private QueueDao queueDao;
+
+    @Autowired
+    private TaskDao taskDao;
+
+    @Transactional(propagation = REQUIRED)
+    public Queue registerQueue(final String name, final int interval, AsyncCallable callable) throws SchedulerException {
+        log.info("registerQueue: ENTER");
+
+        Queue q = queueDao.findByName(name);
+
+        log.info("q = {}", q);
+
+        final long interval_;
+        if (q == null) {
+            q = new Queue(name, interval);
+            queueDao.insert(q);
+            interval_ = interval;
+        } else {
+            // Found an existing queue. Use the Settings from the database.
+            interval_ = q.interval;
+        }
+
+        final QueueThread queueThread = new QueueThread(q, taskDao, transactionTemplate, callable);
+        queues.put(name, queueThread);
+
+        registerSynchronization(new TransactionSynchronizationAdapter() {
+            public void afterCompletion(int status) {
+                log.info("Transaction completed with status = {}", status);
+                if (status == TransactionSynchronization.STATUS_COMMITTED) {
+                    log.info("Starting thread for queue {} with poll interval = {}s", name, interval);
+                    executor.scheduleAtFixedRate(new Runnable() {
+                        public void run() {
+                            queueThread.ping();
+                        }
+                    }, 10, interval_, SECONDS);
+                    Thread thread = new Thread(queueThread, name);
+                    thread.setDaemon(true);
+                    thread.start();
+                }
+            }
+        });
+
+        log.info("registerQueue: LEAVE");
+        return q;
+    }
+
+    public Queue getQueue(String name) {
+        QueueThread queueThread = queues.get(name);
+
+        if (queueThread == null) {
+            throw new RuntimeException("No such queue: '" + name + "'.");
+        }
+
+        return queueThread.queue;
+    }
+
+    @Transactional(propagation = REQUIRED)
+    public Task schedule(final Queue queue, String... args) {
+        return scheduleInner(null, queue, args);
+    }
+
+    public Task schedule(long parent, Queue queue, String... args) {
+        return scheduleInner(parent, queue, args);
+    }
+
+    private Task scheduleInner(Long parent, final Queue queue, String... args) {
+        Date scheduled = new Date();
+
+        StringBuilder arguments = new StringBuilder();
+        for (String arg : args) {
+            arguments.append(arg).append(' ');
+        }
+
+        long id = taskDao.insert(parent, queue.name, scheduled, arguments.toString());
+        Task task = new Task(parent, id, queue.name, scheduled, null, 0, null, asList(args));
+        log.info("Created task = {}", task);
+
+        registerSynchronization(new TransactionSynchronizationAdapter() {
+            public void afterCompletion(int status) {
+                if (status == TransactionSynchronization.STATUS_COMMITTED) {
+                    queues.get(queue.name).ping();
+                }
+            }
+        });
+
+        return task;
+    }
+
+    @Transactional
+    public Task await(Task task, long timeout) {
+        final long start = currentTimeMillis();
+        final long end = start + timeout;
+
+        while (currentTimeMillis() < end) {
+            task = update(task);
+
+            try {
+                sleep(100);
+            } catch (InterruptedException e) {
+                // break
+            }
+        }
+
+        return task;
+    }
+
+    @Transactional(readOnly = true)
+    public Task update(Task ref) {
+        return taskDao.findById(ref.id);
+    }
+}
diff --git a/src/main/java/io/trygvis/async/QueueThread.java b/src/main/java/io/trygvis/async/QueueThread.java
new file mode 100644
index 0000000..69466df
--- /dev/null
+++ b/src/main/java/io/trygvis/async/QueueThread.java
@@ -0,0 +1,119 @@
+package io.trygvis.async;
+
+import io.trygvis.queue.Queue;
+import io.trygvis.queue.Task;
+import io.trygvis.queue.TaskDao;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.transaction.TransactionException;
+import org.springframework.transaction.TransactionStatus;
+import org.springframework.transaction.support.TransactionCallback;
+import org.springframework.transaction.support.TransactionCallbackWithoutResult;
+import org.springframework.transaction.support.TransactionTemplate;
+
+import java.util.Date;
+import java.util.List;
+
+class QueueThread implements Runnable {
+    private final Logger log = LoggerFactory.getLogger(getClass());
+
+    public boolean shouldRun = true;
+
+    private boolean checkForNewTasks;
+
+    private boolean busy;
+
+    public final Queue queue;
+
+    private final TaskDao taskDao;
+
+    private final TransactionTemplate transactionTemplate;
+
+    private final AsyncService.AsyncCallable callable;
+
+    QueueThread(Queue queue, TaskDao taskDao, TransactionTemplate transactionTemplate, AsyncService.AsyncCallable callable) {
+        this.queue = queue;
+        this.taskDao = taskDao;
+        this.transactionTemplate = transactionTemplate;
+        this.callable = callable;
+    }
+
+    public void ping() {
+        synchronized (this) {
+            if (!busy) {
+                log.info("Sending ping to " + queue);
+                notify();
+            } else {
+                checkForNewTasks = true;
+            }
+        }
+    }
+
+    public void run() {
+        while (shouldRun) {
+            try {
+                List<Task> tasks = transactionTemplate.execute(new TransactionCallback<List<Task>>() {
+                    public List<Task> doInTransaction(TransactionStatus status) {
+                        return taskDao.findByNameAndCompletedIsNull(queue.name);
+                    }
+                });
+
+                log.info("Found {} tasks on queue {}", tasks.size(), queue.name);
+
+                if(tasks.size() > 0) {
+                    for (final Task task : tasks) {
+                        try {
+                            executeTask(task);
+                        } catch (TransactionException | TaskFailureException e) {
+                            log.warn("Task execution failed", e);
+                        }
+                    }
+                }
+            } catch (Throwable e) {
+                log.warn("Error while executing tasks.", e);
+            }
+
+            synchronized (this) {
+                busy = false;
+
+                if (checkForNewTasks) {
+                    log.info("Ping received!");
+                    checkForNewTasks = false;
+                    continue;
+                }
+
+                try {
+                    wait();
+                } catch (InterruptedException e) {
+                    // ignore
+                }
+
+                busy = true;
+            }
+        }
+    }
+
+    private void executeTask(final Task task) {
+        final Date run = new Date();
+        log.info("Setting last run on task. date = {}, task = {}", run, task);
+        transactionTemplate.execute(new TransactionCallbackWithoutResult() {
+            protected void doInTransactionWithoutResult(TransactionStatus status) {
+                taskDao.update(task.registerRun());
+            }
+        });
+
+        transactionTemplate.execute(new TransactionCallbackWithoutResult() {
+            protected void doInTransactionWithoutResult(TransactionStatus status) {
+                try {
+                    callable.run(task.arguments);
+                    Date completed = new Date();
+                    Task t = task.registerComplete(completed);
+                    log.info("Completed task: {}", t);
+                    taskDao.update(t);
+                } catch (Exception e) {
+                    throw new TaskFailureException(e);
+                }
+            }
+        });
+    }
+}
diff --git a/src/main/java/io/trygvis/async/TaskFailureException.java b/src/main/java/io/trygvis/async/TaskFailureException.java
new file mode 100644
index 0000000..7278e17
--- /dev/null
+++ b/src/main/java/io/trygvis/async/TaskFailureException.java
@@ -0,0 +1,7 @@
+package io.trygvis.async;
+
+class TaskFailureException extends RuntimeException {
+    public TaskFailureException(Exception e) {
+        super(e);
+    }
+}