[Fix serverlessworkflow#932] Workflow scheduler (serverlessworkflow#966)

Signed-off-by: fjtirado <ftirados@redhat.com>
Signed-off-by: Dmitrii Tikhomirov <chani.liet@gmail.com>

Author: fjtirado

impl/core/pom.xml

@@ -24,5 +24,9 @@
             <groupId>de.huxhorn.sulky</groupId>
             <artifactId>de.huxhorn.sulky.ulid</artifactId>
         </dependency>
+        <dependency>
+            <groupId>com.cronutils</groupId>
+            <artifactId>cron-utils</artifactId>
+        </dependency>
     </dependencies>
 </project>

impl/core/src/main/java/io/serverlessworkflow/impl/SchedulerListener.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.serverlessworkflow.impl;
+
+import io.serverlessworkflow.impl.lifecycle.WorkflowCompletedEvent;
+import io.serverlessworkflow.impl.lifecycle.WorkflowExecutionListener;
+import io.serverlessworkflow.impl.scheduler.Cancellable;
+import io.serverlessworkflow.impl.scheduler.WorkflowScheduler;
+import java.time.Duration;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+class SchedulerListener implements WorkflowExecutionListener, AutoCloseable {
+
+  private final WorkflowScheduler scheduler;
+  private final Map<WorkflowDefinition, WorkflowValueResolver<Duration>> afterMap =
+      new ConcurrentHashMap<>();
+  private final Map<WorkflowDefinition, Cancellable> cancellableMap = new ConcurrentHashMap<>();
+
+  public SchedulerListener(WorkflowScheduler scheduler) {
+    this.scheduler = scheduler;
+  }
+
+  public void addAfter(WorkflowDefinition definition, WorkflowValueResolver<Duration> after) {
+    afterMap.put(definition, after);
+  }
+
+  @Override
+  public void onWorkflowCompleted(WorkflowCompletedEvent ev) {
+    WorkflowDefinition workflowDefinition = (WorkflowDefinition) ev.workflowContext().definition();
+    WorkflowValueResolver<Duration> after = afterMap.get(workflowDefinition);
+    if (after != null) {
+      cancellableMap.put(
+          workflowDefinition,
+          scheduler.scheduleAfter(
+              workflowDefinition,
+              after.apply((WorkflowContext) ev.workflowContext(), null, ev.output())));
+    }
+  }
+
+  public void removeAfter(WorkflowDefinition definition) {
+    if (afterMap.remove(definition) != null) {
+      Cancellable cancellable = cancellableMap.remove(definition);
+      if (cancellable != null) {
+        cancellable.cancel();
+      }
+    }
+  }
+
+  @Override
+  public void close() {
+    cancellableMap.values().forEach(c -> c.cancel());
+    cancellableMap.clear();
+    afterMap.clear();
+  }
+}

impl/core/src/main/java/io/serverlessworkflow/impl/WorkflowApplication.java

@@ -36,6 +36,7 @@
 import io.serverlessworkflow.impl.resources.ExternalResourceHandler;
 import io.serverlessworkflow.impl.resources.ResourceLoaderFactory;
 import io.serverlessworkflow.impl.scheduler.DefaultWorkflowScheduler;
+import io.serverlessworkflow.impl.scheduler.WorkflowScheduler;
 import io.serverlessworkflow.impl.schema.SchemaValidator;
 import io.serverlessworkflow.impl.schema.SchemaValidatorFactory;
 import java.util.ArrayList;
@@ -71,6 +72,7 @@ public class WorkflowApplication implements AutoCloseable {
   private final Map<String, WorkflowAdditionalObject<?>> additionalObjects;
   private final ConfigManager configManager;
   private final SecretManager secretManager;
+  private final SchedulerListener schedulerListener;
 
   private WorkflowApplication(Builder builder) {
     this.taskFactory = builder.taskFactory;
@@ -81,13 +83,14 @@ private WorkflowApplication(Builder builder) {
     this.idFactory = builder.idFactory;
     this.runtimeDescriptorFactory = builder.descriptorFactory;
     this.executorFactory = builder.executorFactory;
-    this.listeners = builder.listeners != null ? builder.listeners : Collections.emptySet();
+    this.listeners = builder.listeners;
     this.definitions = new ConcurrentHashMap<>();
     this.eventConsumer = builder.eventConsumer;
     this.eventPublishers = builder.eventPublishers;
     this.lifeCycleCEPublishingEnabled = builder.lifeCycleCEPublishingEnabled;
     this.modelFactory = builder.modelFactory;
     this.scheduler = builder.scheduler;
+    this.schedulerListener = builder.schedulerListener;
     this.additionalObjects = builder.additionalObjects;
     this.configManager = builder.configManager;
     this.secretManager = builder.secretManager;
@@ -169,6 +172,7 @@ public SchemaValidator getValidator(SchemaInline inline) {
     private Map<String, WorkflowAdditionalObject<?>> additionalObjects;
     private SecretManager secretManager;
     private ConfigManager configManager;
+    private SchedulerListener schedulerListener;
 
     private Builder() {}
 
@@ -304,6 +308,8 @@ public WorkflowApplication build() {
       if (scheduler == null) {
         scheduler = new DefaultWorkflowScheduler();
       }
+      schedulerListener = new SchedulerListener(scheduler);
+      listeners.add(schedulerListener);
       if (additionalObjects == null) {
         additionalObjects = Collections.emptyMap();
       }
@@ -388,6 +394,10 @@ public SecretManager secretManager() {
     return secretManager;
   }
 
+  SchedulerListener schedulerListener() {
+    return schedulerListener;
+  }
+
   public <T> Optional<T> additionalObject(
       String name, WorkflowContext workflowContext, TaskContext taskContext) {
     return Optional.ofNullable(additionalObjects.get(name))

impl/core/src/main/java/io/serverlessworkflow/impl/WorkflowDefinition.java

@@ -20,24 +20,27 @@
 import static io.serverlessworkflow.impl.WorkflowUtils.safeClose;
 
 import io.serverlessworkflow.api.types.Input;
-import io.serverlessworkflow.api.types.ListenTo;
 import io.serverlessworkflow.api.types.Output;
 import io.serverlessworkflow.api.types.Schedule;
 import io.serverlessworkflow.api.types.Workflow;
 import io.serverlessworkflow.impl.events.EventRegistrationBuilderInfo;
 import io.serverlessworkflow.impl.executors.TaskExecutor;
 import io.serverlessworkflow.impl.executors.TaskExecutorHelper;
 import io.serverlessworkflow.impl.resources.ResourceLoader;
+import io.serverlessworkflow.impl.scheduler.Cancellable;
 import io.serverlessworkflow.impl.scheduler.ScheduledEventConsumer;
+import io.serverlessworkflow.impl.scheduler.WorkflowScheduler;
 import io.serverlessworkflow.impl.schema.SchemaValidator;
 import java.nio.file.Path;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Optional;
 
 public class WorkflowDefinition implements AutoCloseable, WorkflowDefinitionData {
 
   private final Workflow workflow;
+  private final WorkflowDefinitionId definitionId;
   private Optional<SchemaValidator> inputSchemaValidator = Optional.empty();
   private Optional<SchemaValidator> outputSchemaValidator = Optional.empty();
   private Optional<WorkflowFilter> inputFilter = Optional.empty();
@@ -47,10 +50,13 @@ public class WorkflowDefinition implements AutoCloseable, WorkflowDefinitionData
   private final ResourceLoader resourceLoader;
   private final Map<String, TaskExecutor<?>> executors = new HashMap<>();
   private ScheduledEventConsumer scheculedConsumer;
+  private Cancellable everySchedule;
+  private Cancellable cronSchedule;
 
   private WorkflowDefinition(
       WorkflowApplication application, Workflow workflow, ResourceLoader resourceLoader) {
     this.workflow = workflow;
+    this.definitionId = WorkflowDefinitionId.of(workflow);
     this.application = application;
     this.resourceLoader = resourceLoader;
 
@@ -84,15 +90,28 @@ static WorkflowDefinition of(WorkflowApplication application, Workflow workflow,
             application.resourceLoaderFactory().getResourceLoader(application, path));
     Schedule schedule = workflow.getSchedule();
     if (schedule != null) {
-      ListenTo to = schedule.getOn();
-      if (to != null) {
+      WorkflowScheduler scheduler = application.scheduler();
+      if (schedule.getOn() != null) {
         definition.scheculedConsumer =
-            application
-                .scheduler()
-                .eventConsumer(
-                    definition,
-                    application.modelFactory()::from,
-                    EventRegistrationBuilderInfo.from(application, to, x -> null));
+            scheduler.eventConsumer(
+                definition,
+                application.modelFactory()::from,
+                EventRegistrationBuilderInfo.from(application, schedule.getOn(), x -> null));
+      }
+      if (schedule.getAfter() != null) {
+        application
+            .schedulerListener()
+            .addAfter(definition, WorkflowUtils.fromTimeoutAfter(application, schedule.getAfter()));
+      }
+      if (schedule.getCron() != null) {
+        definition.cronSchedule = scheduler.scheduleCron(definition, schedule.getCron());
+      }
+      if (schedule.getEvery() != null) {
+        definition.everySchedule =
+            scheduler.scheduleEvery(
+                definition,
+                WorkflowUtils.fromTimeoutAfter(application, schedule.getEvery())
+                    .apply(null, null, application.modelFactory().fromNull()));
       }
     }
     return definition;
@@ -148,7 +167,28 @@ public void addTaskExecutor(WorkflowMutablePosition position, TaskExecutor<?> ta
 
   @Override
   public void close() {
-    safeClose(scheculedConsumer);
     safeClose(resourceLoader);
+    safeClose(scheculedConsumer);
+    application.schedulerListener().removeAfter(this);
+    if (everySchedule != null) {
+      everySchedule.cancel();
+    }
+    if (cronSchedule != null) {
+      cronSchedule.cancel();
+    }
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(definitionId);
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (this == obj) return true;
+    if (obj == null) return false;
+    if (getClass() != obj.getClass()) return false;
+    WorkflowDefinition other = (WorkflowDefinition) obj;
+    return Objects.equals(definitionId, other.definitionId);
   }
 }

impl/core/src/main/java/io/serverlessworkflow/impl/scheduler/Cancellable.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.serverlessworkflow.impl.scheduler;
+
+public interface Cancellable {
+  void cancel();
+}

impl/core/src/main/java/io/serverlessworkflow/impl/scheduler/CronResolver.java

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.serverlessworkflow.impl.scheduler;
+
+import java.time.Duration;
+import java.util.Optional;
+
+public interface CronResolver {
+  Optional<Duration> nextExecution();
+}

impl/core/src/main/java/io/serverlessworkflow/impl/scheduler/CronResolverFactory.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.serverlessworkflow.impl.scheduler;
+
+public interface CronResolverFactory {
+  CronResolver parseCron(String cron);
+}

impl/core/src/main/java/io/serverlessworkflow/impl/scheduler/CronUtilsResolver.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.serverlessworkflow.impl.scheduler;
+
+import com.cronutils.model.Cron;
+import com.cronutils.model.time.ExecutionTime;
+import java.time.Duration;
+import java.time.ZonedDateTime;
+import java.util.Optional;
+
+class CronUtilsResolver implements CronResolver {
+
+  private final ExecutionTime executionTime;
+
+  public CronUtilsResolver(Cron cron) {
+    this.executionTime = ExecutionTime.forCron(cron);
+  }
+
+  @Override
+  public Optional<Duration> nextExecution() {
+    return executionTime.timeToNextExecution(ZonedDateTime.now());
+  }
+}

impl/core/src/main/java/io/serverlessworkflow/impl/scheduler/CronUtilsResolverFactory.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.serverlessworkflow.impl.scheduler;
+
+import com.cronutils.model.CronType;
+import com.cronutils.model.definition.CronDefinitionBuilder;
+import com.cronutils.parser.CronParser;
+
+class CronUtilsResolverFactory implements CronResolverFactory {
+
+  private final CronParser cronParser;
+
+  public CronUtilsResolverFactory() {
+    this(CronType.UNIX);
+  }
+
+  public CronUtilsResolverFactory(CronType type) {
+    this.cronParser = new CronParser(CronDefinitionBuilder.instanceDefinitionFor(type));
+  }
+
+  @Override
+  public CronResolver parseCron(String cron) {
+    return new CronUtilsResolver(cronParser.parse(cron));
+  }
+}