Make index.warmer.enabled setting dynamic

Even though proposed in the documentation, the realtime enabling/disabling of
index warmers was not supported. This commit adds support for
index.warmer.enabled as a dynamic setting.

Closes #3246

src/main/java/org/elasticsearch/index/settings/IndexDynamicSettingsModule.java

@@ -39,6 +39,7 @@
 import org.elasticsearch.index.translog.TranslogService;
 import org.elasticsearch.index.translog.fs.FsTranslog;
 import org.elasticsearch.indices.ttl.IndicesTTLService;
+import org.elasticsearch.indices.warmer.InternalIndicesWarmer;
 
 /**
  */
@@ -113,6 +114,7 @@ public IndexDynamicSettingsModule() {
         indexDynamicSettings.addDynamicSetting(TranslogService.INDEX_TRANSLOG_FLUSH_THRESHOLD_SIZE, Validator.BYTES_SIZE);
         indexDynamicSettings.addDynamicSetting(TranslogService.INDEX_TRANSLOG_FLUSH_THRESHOLD_PERIOD, Validator.TIME);
         indexDynamicSettings.addDynamicSetting(TranslogService.INDEX_TRANSLOG_DISABLE_FLUSH);
+        indexDynamicSettings.addDynamicSetting(InternalIndicesWarmer.INDEX_WARMER_ENABLED);
     }
 
     public void addDynamicSettings(String... settings) {

src/main/java/org/elasticsearch/indices/warmer/InternalIndicesWarmer.java

@@ -38,6 +38,8 @@
  */
 public class InternalIndicesWarmer extends AbstractComponent implements IndicesWarmer {
 
+    public static final String INDEX_WARMER_ENABLED = "index.warmer.enabled";
+
     private final ThreadPool threadPool;
 
     private final ClusterService clusterService;
@@ -69,7 +71,7 @@ public void warm(final WarmerContext context) {
         if (indexMetaData == null) {
             return;
         }
-        if (!indexMetaData.settings().getAsBoolean("index.warmer.enabled", settings.getAsBoolean("index.warmer.enabled", true))) {
+        if (!indexMetaData.settings().getAsBoolean(INDEX_WARMER_ENABLED, settings.getAsBoolean(INDEX_WARMER_ENABLED, true))) {
             return;
         }
         IndexService indexService = indicesService.indexService(context.shardId().index().name());

src/test/java/org/elasticsearch/test/integration/indices/wamer/SimpleIndicesWarmerTests.java

@@ -19,6 +19,7 @@
 
 package org.elasticsearch.test.integration.indices.wamer;
 
+import org.elasticsearch.action.admin.indices.stats.IndicesStatsResponse;
 import org.elasticsearch.action.admin.indices.warmer.get.GetWarmersResponse;
 import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.common.Priority;
@@ -32,6 +33,8 @@
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.greaterThan;
+import static org.hamcrest.Matchers.is;
 
 /**
  */
@@ -175,4 +178,33 @@ public void deleteNonExistentIndexWarmerTest() {
         }
     }
 
+    @Test // issue 3246
+    public void ensureThatIndexWarmersCanBeChangedOnRuntime() throws Exception {
+        client().admin().indices().prepareDelete().execute().actionGet();
+        client().admin().indices().prepareCreate("test")
+                .setSettings(ImmutableSettings.settingsBuilder().put("index.number_of_shards", 1))
+                .execute().actionGet();
+
+        client().admin().cluster().prepareHealth("test").setWaitForGreenStatus().execute().actionGet();
+
+        client().admin().indices().preparePutWarmer("custom_warmer")
+                .setSearchRequest(client().prepareSearch("test").setTypes("test").setQuery(QueryBuilders.matchAllQuery()))
+                .execute().actionGet();
+
+        client().prepareIndex("test", "test", "1").setSource("{ \"foo\" : \"bar\"}").setRefresh(true).execute().actionGet();
+
+        client().admin().indices().prepareUpdateSettings("test").setSettings("{ \"index.warmer.enabled\": false}").execute().actionGet();
+
+        long warmerRunsAfterDisabling = getWarmerRuns();
+        assertThat(warmerRunsAfterDisabling, is(greaterThan(1L)));
+
+        client().prepareIndex("test", "test", "2").setSource("{ \"foo2\" : \"bar2\"}").setRefresh(true).execute().actionGet();
+
+        assertThat(warmerRunsAfterDisabling, is(getWarmerRuns()));
+    }
+
+    private long getWarmerRuns() {
+        IndicesStatsResponse indicesStatsResponse = client().admin().indices().prepareStats("test").clear().setWarmer(true).execute().actionGet();
+        return indicesStatsResponse.getIndex("test").getPrimaries().warmer.total();
+    }
 }