Initial draft of SimpleBuildWrapper.

core/src/main/java/jenkins/tasks/SimpleBuildWrapper.java

+/*
+ * The MIT License
+ *
+ * Copyright 2015 Jesse Glick.
+ *
+ * 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 jenkins.tasks;
+
+import hudson.AbortException;
+import hudson.EnvVars;
+import hudson.FilePath;
+import hudson.Launcher;
+import hudson.model.AbstractBuild;
+import hudson.model.AbstractProject;
+import hudson.model.Action;
+import hudson.model.BuildListener;
+import hudson.model.Run;
+import hudson.model.TaskListener;
+import hudson.tasks.BuildWrapper;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.Serializable;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * A generalization of {@link BuildWrapper} that, like {@link SimpleBuildStep}, may be called at various points within a build.
+ * <p>Such a build wrapper would typically be written according to make few assumptions about how it is being used.
+ * @since TODO
+ */
+@SuppressWarnings("rawtypes") // inherited
+public abstract class SimpleBuildWrapper extends BuildWrapper {
+
+    /**
+     * Called when a segment of a build is started that is to be enhanced with this wrapper.
+     * @param context a way of collecting modifications to the environment for nested steps
+     * @param build a build being run
+     * @param workspace a workspace of the build
+     * @param launcher a way to start commands
+     * @param listener a way to report progress
+     * @param initialEnvironment the environment variables set at the outset
+     * @throws IOException if something fails; {@link AbortException} for user errors
+     * @throws InterruptedException if setup is interrupted
+     */
+    public abstract void setUp(Context context, Run<?,?> build, FilePath workspace, Launcher launcher, TaskListener listener, EnvVars initialEnvironment) throws IOException, InterruptedException;
+
+    public static final class Context {
+        // TODO convert to bean or builder pattern
+        public Disposer disposer;
+        public EnvVars env;
+    }
+
+    /**
+     * An optional callback to run at the end of the wrapped block.
+     */
+    public static abstract class Disposer implements Serializable {
+        public abstract void tearDown(Run<?,?> build, FilePath workspace, Launcher launcher, TaskListener listener);
+    }
+
+    /**
+     * By default, when run as part of an {@link AbstractBuild}, will run late, in the {@link #setUp(AbstractBuild, Launcher, BuildListener)} phase.
+     * May be overridden to return true, in which case this will run earlier, in the {@link #preCheckout} phase.
+     * Ignored when not run as part of an {@link AbstractBuild}.
+     */
+    protected boolean runPreCheckout() {
+        return false;
+    }
+
+    @Override public final Environment setUp(AbstractBuild build, final Launcher launcher, BuildListener listener) throws IOException, InterruptedException {
+        if (runPreCheckout()) {
+            return new Environment() {};
+        } else {
+            final Context c = new Context();
+            setUp(c, build, build.getWorkspace(), launcher, listener, build.getEnvironment(listener));
+            return new EnvironmentWrapper(c, launcher);
+        }
+    }
+
+    @Override public final void preCheckout(AbstractBuild build, final Launcher launcher, BuildListener listener) throws IOException, InterruptedException {
+        if (runPreCheckout()) {
+            final Context c = new Context();
+            setUp(c, build, build.getWorkspace(), launcher, listener, build.getEnvironment(listener));
+            build.getEnvironments().add(new EnvironmentWrapper(c, launcher));
+        }
+    }
+
+    private static class EnvironmentWrapper extends Environment {
+        private final Context c;
+        private final Launcher launcher;
+        EnvironmentWrapper(Context c, Launcher launcher) {
+            this.c = c;
+            this.launcher = launcher;
+        }
+        @Override public void buildEnvVars(Map<String,String> env) {
+            if (c.env != null) {
+                env.putAll(c.env);
+            }
+        }
+        @Override public boolean tearDown(AbstractBuild build, BuildListener listener) throws IOException, InterruptedException {
+            if (c.disposer != null) {
+                c.disposer.tearDown(build, build.getWorkspace(), launcher, listener);
+            }
+            return true;
+        }
+    }
+
+    @Override public final OutputStream decorateLogger(AbstractBuild build, OutputStream logger) throws IOException, InterruptedException, Run.RunnerAbortedException {
+        // Doubtful this can be supported.
+        // Decorating a TaskListener would be more reasonable.
+        // But for an AbstractBuild this is called early in Run.execute, before setUp.
+        // And for other kinds of builds, it is unclear what this would even mean.
+        return logger;
+    }
+
+    @Override public final Launcher decorateLauncher(AbstractBuild build, Launcher launcher, BuildListener listener) throws IOException, InterruptedException, Run.RunnerAbortedException {
+        // TODO reasonable to decorate Launcher within a dynamic scope, but this signature does not mix well with Context pattern.
+        // Called from AbstractBuildExecution.createLauncher; how do we track what is decorating what?
+        // Would have to keep something like a LaunchedDecorator, not an actual Launcher, in Context.
+        // And createLauncher is called before even preCheckout, so much too early for the Context to have been prepared.
+        // Could perhaps create a proxy Launcher whose launch method checks some field in the Context remembered for the build.
+        return launcher;
+    }
+
+    /**
+     * May not do anything.
+     * {@inheritDoc}
+     */
+    @Override public final void makeBuildVariables(AbstractBuild build, Map<String,String> variables) {}
+
+    /**
+     * May not do anything.
+     * {@inheritDoc}
+     */
+    @Override public final void makeSensitiveBuildVariables(AbstractBuild build, Set<String> sensitiveVariables) {
+        // TODO determine if there is a meaningful way to generalize this; perhaps as a new [Run]Action recording sensitiveVariables?
+        // Complicated by the fact that in principle someone could call getSensitiveBuildVariables *before* the wrapper starts and actually sets those variables,
+        // though in practice the likely use cases would come later, and perhaps it is acceptable to omit the names of variables which are yet to be set.
+        // Also unclear if there is any use case for calling this method after the build is done (or Jenkins is restarted);
+        // most likely it is only used during the build itself.
+        // Would be much cleaner if EnvVars itself recorded which keys had sensitive values.
+    }
+
+    /**
+     * {@inheritDoc}
+     * @return an empty set; this might never be called if the step is not part of the static configuration of a project; instead, add a {@link SimpleBuildStep.LastBuildAction} to a build when run
+     */
+    @Override public final Collection<? extends Action> getProjectActions(AbstractProject job) {
+        return Collections.emptySet();
+    }
+
+}