add API to get last index time

fixes #3423

Author: Vladimir Kotal

apiary.apib

@@ -181,6 +181,17 @@ Honors the Accept header. The text type works for plain text files only.
 
 + Response 204
 
+## Get last index time [/system/indextime]
+
+The time is in the ISO 8601 format in UTC time zone.
+
+### Retrieve last index time [GET]
+
++ Response 200 (application/json)
+  + Body
+
+    "2021-02-15T16:39:16.409+00:00"
+
 ## Index searchers refresh [/system/refresh]
 
 ### refreshes index searchers for specified project [PUT]

opengrok-web/src/main/java/org/opengrok/web/api/v1/controller/SystemController.java

@@ -22,6 +22,10 @@
  */
 package org.opengrok.web.api.v1.controller;
 
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.SerializationFeature;
+import com.fasterxml.jackson.databind.util.StdDateFormat;
 import org.opengrok.indexer.configuration.RuntimeEnvironment;
 import org.opengrok.indexer.web.EftarFile;
 import org.opengrok.indexer.logger.LoggerFactory;
@@ -31,12 +35,17 @@
 import javax.inject.Inject;
 import javax.validation.Valid;
 import javax.ws.rs.Consumes;
+import javax.ws.rs.GET;
 import javax.ws.rs.POST;
 import javax.ws.rs.PUT;
 import javax.ws.rs.Path;
+import javax.ws.rs.Produces;
 import javax.ws.rs.core.MediaType;
+import java.io.File;
 import java.io.IOException;
+import java.nio.file.Paths;
 import java.util.Collections;
+import java.util.Date;
 import java.util.Set;
 import java.util.concurrent.CompletableFuture;
 import java.util.logging.Level;
@@ -74,4 +83,17 @@ public void loadPathDescriptions(@Valid final PathDescription[] descriptions) th
         ef.create(Set.of(descriptions), env.getDtagsEftarPath().toString());
         LOGGER.log(Level.INFO, "reloaded path descriptions with {0} entries", descriptions.length);
     }
+
+    @GET
+    @Path("/indextime")
+    @Produces(MediaType.APPLICATION_JSON)
+    public String getIndexTime() throws JsonProcessingException {
+        File indexTimeFile = Paths.get(env.getDataRootFile().toString(), "timestamp").toFile();
+        Date date = new Date(indexTimeFile.lastModified());
+        ObjectMapper mapper = new ObjectMapper();
+        // StdDateFormat is ISO8601 since jackson 2.9
+        mapper.setDateFormat(new StdDateFormat().withColonInTimeZone(true));
+        String result = mapper.writeValueAsString(date);
+        return result;
+    }
 }

opengrok-web/src/test/java/org/opengrok/web/api/v1/controller/SystemControllerTest.java

@@ -40,9 +40,15 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.util.Calendar;
+import java.util.Date;
 
+import static org.hamcrest.Matchers.containsString;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
 
 public class SystemControllerTest extends OGKJerseyTest {
@@ -130,4 +136,26 @@ public void testDtagsEftarReload() throws IOException {
         // Cleanup
         IOUtils.removeRecursive(dataRoot);
     }
+
+    @Test
+    public void testIndexTime() throws IOException, ParseException {
+        Path dataRoot = Files.createTempDirectory("indexTimetest");
+        env.setDataRoot(dataRoot.toString());
+        File indexTimeFile = Paths.get(dataRoot.toString(), "timestamp").toFile();
+        indexTimeFile.createNewFile();
+        assertTrue(indexTimeFile.exists());
+        SimpleDateFormat f = new SimpleDateFormat("yyyy-MM-dd_hh:mm:ss+ZZ");
+        Date date = f.parse("2021-02-16_11:18:01+UTC");
+        indexTimeFile.setLastModified(date.getTime());
+
+        Response r = target("system")
+                .path("indextime")
+                .request().get();
+        String result = r.readEntity(String.class);
+
+        assertThat(result, containsString("2021-02-16T11:18:01.000+00:00"));
+
+        // Cleanup
+        IOUtils.removeRecursive(dataRoot);
+    }
 }