Teach reindex to stop when cancelled

All we do is check the cancelled flag and stop the request at a few key
points.

Adds the cancellation cause to the status so any request that is cancelled
but doesn't die can be seen in the task list.

core/src/main/java/org/elasticsearch/tasks/CancellableTask.java

@@ -19,6 +19,8 @@
 
 package org.elasticsearch.tasks;
 
+import org.elasticsearch.common.Nullable;
+
 import java.util.concurrent.atomic.AtomicReference;
 
 /**
@@ -56,4 +58,11 @@ public boolean isCancelled() {
         return reason.get() != null;
     }
 
+    /**
+     * The reason the task was cancelled or null if it hasn't been cancelled.
+     */
+    @Nullable
+    public String getReasonCancelled() {
+        return reason.get();
+    }
 }

plugins/reindex/src/main/java/org/elasticsearch/plugin/reindex/AbstractAsyncBulkByScrollAction.java

@@ -113,7 +113,11 @@ public BulkByScrollTask getTask() {
         return task;
     }
 
-    private void initialSearch() {
+    void initialSearch() {
+        if (task.isCancelled()) {
+            finishHim(null);
+            return;
+        }
         try {
             // Default to sorting by _doc if it hasn't been changed.
             if (firstSearchRequest.source().sorts() == null) {
@@ -144,8 +148,19 @@ public void onFailure(Throwable e) {
         }
     }
 
+    /**
+     * Set the last returned scrollId. Package private for testing.
+     */
+    void setScroll(String scroll) {
+        this.scroll.set(scroll);
+    }
+
     void onScrollResponse(SearchResponse searchResponse) {
-        scroll.set(searchResponse.getScrollId());
+        if (task.isCancelled()) {
+            finishHim(null);
+            return;
+        }
+        setScroll(searchResponse.getScrollId());
         if (searchResponse.getShardFailures() != null && searchResponse.getShardFailures().length > 0) {
             startNormalTermination(emptyList(), unmodifiableList(Arrays.asList(searchResponse.getShardFailures())));
             return;
@@ -178,7 +193,7 @@ protected void doRun() throws Exception {
                     /*
                      * If we noop-ed the entire batch then just skip to the next batch or the BulkRequest would fail validation.
                      */
-                    startNextScrollRequest();
+                    startNextScroll();
                     return;
                 }
                 request.timeout(mainRequest.getTimeout());
@@ -198,6 +213,10 @@ public void onFailure(Throwable t) {
     }
 
     void sendBulkRequest(BulkRequest request) {
+        if (task.isCancelled()) {
+            finishHim(null);
+            return;
+        }
         retry.withAsyncBackoff(client, request, new ActionListener<BulkResponse>() {
             @Override
             public void onResponse(BulkResponse response) {
@@ -212,6 +231,10 @@ public void onFailure(Throwable e) {
     }
 
     void onBulkResponse(BulkResponse response) {
+        if (task.isCancelled()) {
+            finishHim(null);
+            return;
+        }
         try {
             List<Failure> failures = new ArrayList<Failure>();
             Set<String> destinationIndicesThisBatch = new HashSet<>();
@@ -252,13 +275,17 @@ void onBulkResponse(BulkResponse response) {
                 startNormalTermination(emptyList(), emptyList());
                 return;
             }
-            startNextScrollRequest();
+            startNextScroll();
         } catch (Throwable t) {
             finishHim(t);
         }
     }
 
-    void startNextScrollRequest() {
+    void startNextScroll() {
+        if (task.isCancelled()) {
+            finishHim(null);
+            return;
+        }
         SearchScrollRequest request = new SearchScrollRequest();
         request.scrollId(scroll.get()).scroll(firstSearchRequest.scroll());
         client.searchScroll(request, new ActionListener<SearchResponse>() {

plugins/reindex/src/main/java/org/elasticsearch/plugin/reindex/BulkByScrollTask.java

@@ -19,9 +19,11 @@
 
 package org.elasticsearch.plugin.reindex;
 
+import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.xcontent.XContentBuilder;
+import org.elasticsearch.tasks.CancellableTask;
 import org.elasticsearch.tasks.Task;
 
 import java.io.IOException;
@@ -31,7 +33,7 @@
 /**
  * Task storing information about a currently running BulkByScroll request.
  */
-public class BulkByScrollTask extends Task {
+public class BulkByScrollTask extends CancellableTask {
     /**
      * The total number of documents this request will process. 0 means we don't yet know or, possibly, there are actually 0 documents
      * to process. Its ok that these have the same meaning because any request with 0 actual documents should be quite short lived.
@@ -52,7 +54,7 @@ public BulkByScrollTask(long id, String type, String action, String description)
     @Override
     public Status getStatus() {
         return new Status(total.get(), updated.get(), created.get(), deleted.get(), batch.get(), versionConflicts.get(), noops.get(),
-                retries.get());
+                retries.get(), getReasonCancelled());
     }
 
     /**
@@ -63,7 +65,7 @@ public long getSuccessfullyProcessed() {
     }
 
     public static class Status implements Task.Status {
-        public static final Status PROTOTYPE = new Status(0, 0, 0, 0, 0, 0, 0, 0);
+        public static final Status PROTOTYPE = new Status(0, 0, 0, 0, 0, 0, 0, 0, null);
 
         private final long total;
         private final long updated;
@@ -73,8 +75,10 @@ public static class Status implements Task.Status {
         private final long versionConflicts;
         private final long noops;
         private final long retries;
+        private final String reasonCancelled;
 
-        public Status(long total, long updated, long created, long deleted, int batches, long versionConflicts, long noops, long retries) {
+        public Status(long total, long updated, long created, long deleted, int batches, long versionConflicts, long noops, long retries,
+                @Nullable String reasonCancelled) {
             this.total = checkPositive(total, "total");
             this.updated = checkPositive(updated, "updated");
             this.created = checkPositive(created, "created");
@@ -83,6 +87,7 @@ public Status(long total, long updated, long created, long deleted, int batches,
             this.versionConflicts = checkPositive(versionConflicts, "versionConflicts");
             this.noops = checkPositive(noops, "noops");
             this.retries = checkPositive(retries, "retries");
+            this.reasonCancelled = reasonCancelled;
         }
 
         public Status(StreamInput in) throws IOException {
@@ -94,6 +99,7 @@ public Status(StreamInput in) throws IOException {
             versionConflicts = in.readVLong();
             noops = in.readVLong();
             retries = in.readVLong();
+            reasonCancelled = in.readOptionalString();
         }
 
         @Override
@@ -106,6 +112,7 @@ public void writeTo(StreamOutput out) throws IOException {
             out.writeVLong(versionConflicts);
             out.writeVLong(noops);
             out.writeVLong(retries);
+            out.writeOptionalString(reasonCancelled);
         }
 
         @Override
@@ -129,6 +136,9 @@ public XContentBuilder innerXContent(XContentBuilder builder, Params params, boo
             builder.field("version_conflicts", versionConflicts);
             builder.field("noops", noops);
             builder.field("retries", retries);
+            if (reasonCancelled != null) {
+                builder.field("canceled", reasonCancelled);
+            }
             return builder;
         }
 
@@ -152,6 +162,9 @@ public void innerToString(StringBuilder builder, boolean includeCreated, boolean
             builder.append(",versionConflicts=").append(versionConflicts);
             builder.append(",noops=").append(noops);
             builder.append(",retries=").append(retries);
+            if (reasonCancelled != null) {
+                builder.append(",canceled=").append(reasonCancelled);
+            }
         }
 
         @Override
@@ -221,6 +234,13 @@ public long getRetries() {
             return retries;
         }
 
+        /**
+         * The reason that the request was canceled or null if it hasn't been.
+         */
+        public String getReasonCancelled() {
+            return reasonCancelled;
+        }
+
         private int checkPositive(int value, String name) {
             if (value < 0) {
                 throw new IllegalArgumentException(name + " must be greater than 0 but was [" + value + "]");

plugins/reindex/src/main/java/org/elasticsearch/plugin/reindex/BulkIndexByScrollResponse.java

@@ -81,6 +81,13 @@ public long getNoops() {
         return status.getNoops();
     }
 
+    /**
+     * The reason that the request was canceled or null if it hasn't been.
+     */
+    public String getReasonCancelled() {
+        return status.getReasonCancelled();
+    }
+
     /**
      * All of the indexing failures. Version conflicts are only included if the request sets abortOnVersionConflict to true (the
      * default).

plugins/reindex/src/test/java/org/elasticsearch/plugin/reindex/AbstractBulkIndexByScrollResponseMatcher.java

@@ -24,6 +24,7 @@
 import org.hamcrest.TypeSafeMatcher;
 
 import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.nullValue;
 
 public abstract class AbstractBulkIndexByScrollResponseMatcher<
                 Response extends BulkIndexByScrollResponse,
@@ -36,6 +37,7 @@ public abstract class AbstractBulkIndexByScrollResponseMatcher<
     private Matcher<Integer> batchesMatcher;
     private Matcher<Long> versionConflictsMatcher = equalTo(0L);
     private Matcher<Integer> failuresMatcher = equalTo(0);
+    private Matcher<String> reasonCancelledMatcher = nullValue(String.class);
 
     protected abstract Self self();
 
@@ -93,13 +95,18 @@ public Self failures(int failures) {
         return failures(equalTo(failures));
     }
 
+    public Self reasonCancelled(Matcher<String> reasonCancelledMatcher) {
+        this.reasonCancelledMatcher = reasonCancelledMatcher;
+        return self();
+    }
 
     @Override
     protected boolean matchesSafely(Response item) {
         return updatedMatcher.matches(item.getUpdated()) &&
             (batchesMatcher == null || batchesMatcher.matches(item.getBatches())) &&
             versionConflictsMatcher.matches(item.getVersionConflicts()) &&
-            failuresMatcher.matches(item.getIndexingFailures().size());
+            failuresMatcher.matches(item.getIndexingFailures().size()) &&
+            reasonCancelledMatcher.matches(item.getReasonCancelled());
     }
 
     @Override
@@ -110,5 +117,6 @@ public void describeTo(Description description) {
         }
         description.appendText(" and versionConflicts matches ").appendDescriptionOf(versionConflictsMatcher);
         description.appendText(" and failures size matches ").appendDescriptionOf(failuresMatcher);
+        description.appendText(" and reason cancelled matches ").appendDescriptionOf(reasonCancelledMatcher);
     }
 }