Merge pull request #96 from abayer/jenkins-58084

[JENKINS-58084] Add StepListener

src/main/java/org/jenkinsci/plugins/workflow/flow/StepListener.java

@@ -0,0 +1,45 @@
+/*
+ * The MIT License
+ *
+ * Copyright (c) 2019, CloudBees, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package org.jenkinsci.plugins.workflow.flow;
+
+import hudson.ExtensionPoint;
+import org.jenkinsci.plugins.workflow.graph.FlowNode;
+import org.jenkinsci.plugins.workflow.steps.Step;
+import org.jenkinsci.plugins.workflow.steps.StepContext;
+
+import javax.annotation.Nonnull;
+
+/**
+ * {@link StepListener}s are fired before invoking a step but after the {@link FlowNode} has been created and the
+ * {@link StepContext} has been populated. A {@link StepListener} can perform actions before the {@link Step} is
+ * executed, such as calling {@link StepContext#onFailure} to make the step fail before it starts.
+ */
+public interface StepListener extends ExtensionPoint {
+    /**
+     * Called before a {@link Step} is invoked, but after its {@link FlowNode} and {@link StepContext} have been created.
+     * Listeners can make the step fail by calling {@link StepContext#onFailure}.
+     */
+    void notifyOfNewStep(@Nonnull Step step, @Nonnull StepContext context);
+}