[FIXED JENKINS-42150] Add latency options to mock scm impl in SCM API's test artifact

src/test/java/jenkins/scm/impl/mock/MockLatency.java

@@ -0,0 +1,120 @@
+/*
+ * The MIT License
+ *
+ * Copyright (c) 2017 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 jenkins.scm.impl.mock;
+
+import java.util.Random;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Represents latency in connecting to the {@link MockSCM}.
+ *
+ * @since 2.0.5
+ */
+public abstract class MockLatency {
+
+    private static final MockLatency NONE = new MockLatency() {
+        @Override
+        public void apply() throws InterruptedException {
+        }
+    };
+    private static final MockLatency YIELD = new MockLatency() {
+        @Override
+        public void apply() throws InterruptedException {
+            Thread.yield();
+        }
+    };
+
+    public abstract void apply() throws InterruptedException;
+
+    /**
+     * A fixed latency.
+     * @param time the latency.
+     * @param units the units.
+     * @return a fixed latency.
+     */
+    public static MockLatency fixed(final long time, final TimeUnit units) {
+        return new MockLatency() {
+            @Override
+            public void apply() throws InterruptedException {
+                units.sleep(time);
+            }
+        };
+    }
+
+    /**
+     * A fixed latency for all threads except the current thread.
+     * 
+     * @param time the latency.
+     * @param units the units.
+     * @return a fixed latency.
+     */
+    public static MockLatency fixedForOtherThreads(final long time, final TimeUnit units) {
+        final Thread safe = Thread.currentThread();
+        return new MockLatency() {
+            @Override
+            public void apply() throws InterruptedException {
+                if (Thread.currentThread() != safe) {
+                    units.sleep(time);
+                }
+            }
+        };
+    }
+
+    /**
+     * A random latency that has an expected average time.
+     *
+     * @param time  the expected average latency.
+     * @param units the units.
+     * @return a fixed latency.
+     */
+    public static MockLatency average(final long time, final TimeUnit units) {
+        return new MockLatency() {
+            final Random entropy = new Random();
+            @Override
+            public void apply() throws InterruptedException {
+                long ms = units.toMillis(time);
+                ms = Math.min(ms * 3L, Math.max((long) (ms + (ms * entropy.nextGaussian())), 1L));
+                Thread.sleep(ms);
+            }
+        };
+    }
+    /**
+     * A latency that just forces the thread scheduler to yield.
+     *
+     * @return a minimal latency that causes background threads to run.
+     */
+    public static MockLatency yield() {
+        return YIELD;
+    }
+    /**
+     * A latency that just forces the thread scheduler to yield.
+     *
+     * @return a minimal latency that causes background threads to run.
+     */
+    public static MockLatency none() {
+        return NONE;
+    }
+}

src/test/java/jenkins/scm/impl/mock/MockSCMController.java

@@ -26,6 +26,7 @@
 package jenkins.scm.impl.mock;
 
 import edu.umd.cs.findbugs.annotations.CheckForNull;
+import edu.umd.cs.findbugs.annotations.NonNull;
 import hudson.FilePath;
 import java.io.ByteArrayInputStream;
 import java.io.Closeable;
@@ -58,6 +59,8 @@ public class MockSCMController implements Closeable {
 
     private Map<String, Repository> repositories = new TreeMap<String, Repository>();
     private List<MockFailure> faults = new ArrayList<MockFailure>();
+    @NonNull
+    private MockLatency latency = MockLatency.none();
     private String displayName;
     private String description;
     private String url;
@@ -80,6 +83,11 @@ public static MockSCMController create() {
         return c;
     }
 
+    public MockSCMController withLatency(@NonNull MockLatency latency) {
+        this.latency = latency;
+        return this;
+    }
+
     /**
      * (Re)creates a {@link MockSCMController} for use when you are running a data migration test.
      * It will be the callers responsibility to restore the state of the {@link MockSCMController} accordingly.
@@ -178,7 +186,8 @@ public synchronized void clearFaults() {
 
     public synchronized void checkFaults(@CheckForNull String repository, @CheckForNull String branch,
                                          @CheckForNull String revision, boolean actions)
-            throws IOException {
+            throws IOException, InterruptedException {
+        latency.apply();
         for (MockFailure fault: faults) {
             fault.check(repository, branch, revision, actions);
         }