Merge pull request #1684 from DanielWeber/JENKINS-9104

[JENKINS-9104] Add extension point that allows extensions to veto killing...
jenkinsci · Jul 5, 2015 · 9a047ac · 9a047ac
2 parents 3c785d5 + a220431
commit 9a047ac
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Showing 3 changed files with 173 additions and 1 deletion.
diff --git a/core/src/main/java/hudson/util/ProcessKillingVeto.java b/core/src/main/java/hudson/util/ProcessKillingVeto.java
@@ -0,0 +1,92 @@
+/*
+ * The MIT License
+ *
+ * Copyright (c) 2015, Daniel Weber
+ *
+ * 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 hudson.util;
+
+import hudson.ExtensionPoint;
+import hudson.util.ProcessTreeRemoting.IOSProcess;
+
+import java.util.Collections;
+import java.util.List;
+
+import javax.annotation.CheckForNull;
+import javax.annotation.Nonnull;
+
+import jenkins.model.Jenkins;
+
+/**
+ * Allows extensions to veto killing processes. If at least one extension vetoes
+ * the killing of a process, it will not be killed. This can be useful to keep
+ * daemon processes alive. An example is mspdbsrv.exe used by Microsoft
+ * compilers.
+ * 
+ * See JENKINS-9104
+ * 
+ * @since TODO
+ * 
+ * @author Daniel Weber <daniel.weber.dev@gmail.com>
+ */
+public abstract class ProcessKillingVeto implements ExtensionPoint {
+
+    /**
+     * Describes the cause for a process killing veto.
+     */
+    public static class VetoCause {
+        private final String message;
+
+        /**
+         * @param message A string describing the reason for the veto
+         */
+        public VetoCause(@Nonnull String message) {
+            this.message = message;
+        }
+
+        /**
+         * @return A string describing the reason for the veto.
+         */
+        public @Nonnull String getMessage() {
+            return message;
+        }
+    }
+
+    /**
+     * @return All ProcessKillingVeto extensions currently registered. An empty
+     *         list if Jenkins is not available, never null.
+     */
+    public static List<ProcessKillingVeto> all() {
+        Jenkins jenkins = Jenkins.getInstance();
+        if (jenkins == null)
+            return Collections.emptyList();
+        return jenkins.getExtensionList(ProcessKillingVeto.class);
+    }
+
+    /**
+     * Ask the extension whether it vetoes killing of the given process
+     * 
+     * @param p The process that is about to be killed
+     * @return a {@link VetoCause} if the process should <em>not</em> be killed,
+     *         null else.
+     */
+    @CheckForNull
+    public abstract VetoCause vetoProcessKilling(@Nonnull IOSProcess p);
+}
diff --git a/core/src/main/java/hudson/util/ProcessTree.java b/core/src/main/java/hudson/util/ProcessTree.java
@@ -32,6 +32,7 @@
 import hudson.remoting.Channel;
 import hudson.remoting.VirtualChannel;
 import hudson.slaves.SlaveComputer;
+import hudson.util.ProcessKillingVeto.VetoCause;
 import hudson.util.ProcessTree.OSProcess;
 import hudson.util.ProcessTreeRemoting.IOSProcess;
 import hudson.util.ProcessTreeRemoting.IProcessTree;
@@ -56,6 +57,7 @@
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
+import javax.annotation.CheckForNull;
 import static com.sun.jna.Pointer.NULL;
 import static hudson.util.jna.GNUCLibrary.LIBC;
 import static java.util.logging.Level.FINE;
@@ -227,6 +229,22 @@ void killByKiller() throws InterruptedException {
          */
         public abstract void killRecursively() throws InterruptedException;
 
+        /**
+         * @return The first non-null {@link VetoCause} provided by a process killing veto extension for this OSProcess. 
+         * null if no one objects killing the process.
+         */
+        protected @CheckForNull VetoCause getVeto() {
+            for (ProcessKillingVeto vetoExtension : ProcessKillingVeto.all()) {
+                VetoCause cause = vetoExtension.vetoProcessKilling(this);
+                if (cause != null) {
+                    if (LOGGER.isLoggable(FINEST))
+                        LOGGER.finest("Killing of pid " + getPid() + " vetoed by " + vetoExtension.getClass().getName() + ": " + cause.getMessage());
+                    return cause;
+                }
+            }
+            return null;
+        }
+
         /**
          * Gets the command-line arguments of this process.
          *
@@ -363,6 +381,8 @@ public void killRecursively() {
                 }
 
                 public void kill() throws InterruptedException {
+                    if (getVeto() != null) 
+                        return;
                     proc.destroy();
                     killByKiller();
                 }
@@ -398,12 +418,18 @@ public OSProcess getParent() {
                     }
 
                     public void killRecursively() throws InterruptedException {
+                        if (getVeto() != null) 
+                            return;
+
                         LOGGER.finer("Killing recursively "+getPid());
                         p.killRecursively();
                         killByKiller();
                     }
 
                     public void kill() throws InterruptedException {
+                        if (getVeto() != null) 
+                            return;
+
                         LOGGER.finer("Killing "+getPid());
                         p.kill();
                         killByKiller();
@@ -537,6 +563,8 @@ protected final File getFile(String relativePath) {
          * Tries to kill this process.
          */
         public void kill() throws InterruptedException {
+            if (getVeto() != null) 
+                return;
             try {
                 int pid = getPid();
                 LOGGER.fine("Killing pid="+pid);
@@ -557,6 +585,7 @@ public void kill() throws InterruptedException {
         }
 
         public void killRecursively() throws InterruptedException {
+            // We kill individual processes of a tree, so handling vetoes inside #kill() is enough for UnixProcess es
             LOGGER.fine("Recursively killing pid="+getPid());
             for (OSProcess p : getChildren())
                 p.killRecursively();

diff --git a/test/src/test/java/hudson/util/ProcessTreeKillerTest.java b/test/src/test/java/hudson/util/ProcessTreeKillerTest.java
@@ -1,21 +1,35 @@
 package hudson.util;
 
+import static org.junit.Assert.*;
+import static org.junit.Assume.*;
+import java.io.File;
 import hudson.Functions;
 import hudson.model.FreeStyleBuild;
 import hudson.model.FreeStyleProject;
 import hudson.tasks.Maven;
 import hudson.tasks.Shell;
+import hudson.util.ProcessTreeRemoting.IOSProcess;
+import org.junit.After;
 import org.junit.Rule;
 import org.junit.Test;
 import org.jvnet.hudson.test.ExtractResourceSCM;
 import org.jvnet.hudson.test.Issue;
 import org.jvnet.hudson.test.JenkinsRule;
+import org.jvnet.hudson.test.TestExtension;
+import com.google.common.collect.ImmutableMap;
 
 public class ProcessTreeKillerTest {
 
     @Rule
     public JenkinsRule j = new JenkinsRule();
-
+    private Process process;
+
+    @After
+    public void tearDown() throws Exception {
+        if (null != process)
+            process.destroy();
+    }    
+
     @Test
 	public void manualAbortProcess() throws Exception {
 		ProcessTree.enabled = true;
@@ -55,4 +69,41 @@ public void processProperlyKilledUnix() throws Exception {
 
         j.assertLogNotContains("sleep 100000", processJob.scheduleBuild2(0).get());
     }
+
+    @Test
+    @Issue("JENKINS-9104")
+    public void considersKillingVetos() throws Exception {
+        // on some platforms where we fail to list any processes, this test will
+        // just not work
+        assumeTrue(ProcessTree.get() != ProcessTree.DEFAULT);
+
+        // kick off a process we (shouldn't) kill
+        ProcessBuilder pb = new ProcessBuilder();
+        pb.environment().put("cookie", "testKeepDaemonsAlive");
+
+        if (File.pathSeparatorChar == ';') {
+            pb.command("cmd");
+        } else {
+            pb.command("sleep", "5m");
+        }
+
+        process = pb.start();
+
+        ProcessTree processTree = ProcessTree.get();
+        processTree.killAll(ImmutableMap.of("cookie", "testKeepDaemonsAlive"));
+        try {
+            process.exitValue();
+            fail("Process should have been excluded from the killing");
+        } catch (IllegalThreadStateException e) {
+            // Means the process is still running
+        }
+    }
+
+    @TestExtension("considersKillingVetos")
+    public static class VetoAllKilling extends ProcessKillingVeto {
+        @Override
+        public VetoCause vetoProcessKilling(IOSProcess p) {
+            return new VetoCause("Peace on earth");
+        }
+    }
 }