[Remote Segments] Retry segment uploads to remote store on failure (#…

…7400)

Signed-off-by: Ashish Singh <ssashish@amazon.com>

server/src/internalClusterTest/java/org/opensearch/remotestore/RemoteStoreRefreshListenerIT.java

@@ -0,0 +1,182 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.remotestore;
+
+import org.junit.After;
+import org.junit.Before;
+import org.opensearch.action.admin.indices.stats.IndicesStatsRequest;
+import org.opensearch.action.admin.indices.stats.IndicesStatsResponse;
+import org.opensearch.action.index.IndexResponse;
+import org.opensearch.cluster.metadata.IndexMetadata;
+import org.opensearch.common.UUIDs;
+import org.opensearch.common.settings.Settings;
+import org.opensearch.common.util.FeatureFlags;
+import org.opensearch.core.util.FileSystemUtils;
+import org.opensearch.index.IndexModule;
+import org.opensearch.index.IndexSettings;
+import org.opensearch.index.store.RemoteSegmentStoreDirectory;
+import org.opensearch.indices.replication.common.ReplicationType;
+import org.opensearch.snapshots.AbstractSnapshotIntegTestCase;
+import org.opensearch.test.FeatureFlagSetter;
+import org.opensearch.test.OpenSearchIntegTestCase;
+
+import java.io.IOException;
+import java.nio.file.Path;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Locale;
+import java.util.Set;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.Collectors;
+
+import static org.opensearch.test.hamcrest.OpenSearchAssertions.assertAcked;
+
+@OpenSearchIntegTestCase.ClusterScope(scope = OpenSearchIntegTestCase.Scope.TEST, numDataNodes = 0)
+public class RemoteStoreRefreshListenerIT extends AbstractSnapshotIntegTestCase {
+
+    private static final String REPOSITORY_NAME = "my-segment-repo-1";
+    private static final String INDEX_NAME = "remote-store-test-idx-1";
+
+    @Override
+    protected Settings featureFlagSettings() {
+        return Settings.builder()
+            .put(super.featureFlagSettings())
+            .put(FeatureFlags.SEGMENT_REPLICATION_EXPERIMENTAL, "true")
+            .put(FeatureFlags.REMOTE_STORE, "true")
+            .build();
+    }
+
+    @Before
+    public void setup() {
+        FeatureFlagSetter.set(FeatureFlags.REMOTE_STORE);
+        internalCluster().startClusterManagerOnlyNode();
+    }
+
+    @Override
+    public Settings indexSettings() {
+        return remoteStoreIndexSettings(0);
+    }
+
+    private Settings remoteStoreIndexSettings(int numberOfReplicas) {
+        return Settings.builder()
+            .put(super.indexSettings())
+            .put(IndexSettings.INDEX_REFRESH_INTERVAL_SETTING.getKey(), "300s")
+            .put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, 1)
+            .put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, numberOfReplicas)
+            .put(IndexModule.INDEX_QUERY_CACHE_ENABLED_SETTING.getKey(), false)
+            .put(IndexMetadata.SETTING_REPLICATION_TYPE, ReplicationType.SEGMENT)
+            .put(IndexMetadata.SETTING_REMOTE_STORE_ENABLED, true)
+            .put(IndexMetadata.SETTING_REMOTE_STORE_REPOSITORY, REPOSITORY_NAME)
+            .build();
+    }
+
+    @After
+    public void teardown() {
+        logger.info("--> Deleting the repository={}", REPOSITORY_NAME);
+        assertAcked(clusterAdmin().prepareDeleteRepository(REPOSITORY_NAME));
+    }
+
+    public void testRemoteRefreshRetryOnFailure() throws Exception {
+
+        Path location = randomRepoPath().toAbsolutePath();
+        setup(location, randomDoubleBetween(0.1, 0.25, true), "metadata");
+
+        // Here we are having flush/refresh after each iteration of indexing. However, the refresh will not always succeed
+        // due to IOExceptions that are thrown while doing uploadBlobs.
+        indexData(randomIntBetween(5, 10), randomBoolean());
+        logger.info("--> Indexed data");
+
+        // TODO - Once the segments stats api is available, we need to verify that there were failed upload attempts.
+        IndicesStatsResponse response = client().admin().indices().stats(new IndicesStatsRequest()).get();
+        assertEquals(1, response.getShards().length);
+
+        String indexUuid = response.getShards()[0].getShardRouting().index().getUUID();
+        Path segmentDataRepoPath = location.resolve(String.format(Locale.ROOT, "%s/0/segments/data", indexUuid));
+        String segmentDataLocalPath = String.format(Locale.ROOT, "%s/indices/%s/0/index", response.getShards()[0].getDataPath(), indexUuid);
+
+        logger.info("--> Verify that the segment files are same on local and repository eventually");
+        // This can take time as the retry interval is exponential and maxed at 30s
+        assertBusy(() -> {
+            Set<String> filesInLocal = getSegmentFiles(location.getRoot().resolve(segmentDataLocalPath));
+            Set<String> filesInRepo = getSegmentFiles(segmentDataRepoPath);
+            assertTrue(filesInRepo.containsAll(filesInLocal));
+        }, 60, TimeUnit.SECONDS);
+    }
+
+    private void setup(Path repoLocation, double ioFailureRate, String skipExceptionBlobList) {
+        logger.info("--> Creating repository={} at the path={}", REPOSITORY_NAME, repoLocation);
+        // The random_control_io_exception_rate setting ensures that 10-25% of all operations to remote store results in
+        /// IOException. skip_exception_on_verification_file & skip_exception_on_list_blobs settings ensures that the
+        // repository creation can happen without failure.
+        createRepository(
+            REPOSITORY_NAME,
+            "mock",
+            Settings.builder()
+                .put("location", repoLocation)
+                .put("random_control_io_exception_rate", ioFailureRate)
+                .put("skip_exception_on_verification_file", true)
+                .put("skip_exception_on_list_blobs", true)
+                .put("max_failure_number", Long.MAX_VALUE)
+        );
+
+        internalCluster().startDataOnlyNodes(1);
+        createIndex(INDEX_NAME);
+        logger.info("--> Created index={}", INDEX_NAME);
+        ensureYellowAndNoInitializingShards(INDEX_NAME);
+        logger.info("--> Cluster is yellow with no initializing shards");
+        ensureGreen(INDEX_NAME);
+        logger.info("--> Cluster is green");
+    }
+
+    /**
+     * Gets all segment files which starts with "_". For instance, _0.cfe, _o.cfs etc.
+     *
+     * @param location the path to location where segment files are being searched.
+     * @return set of file names of all segment file or empty set if there was IOException thrown.
+     */
+    private Set<String> getSegmentFiles(Path location) {
+        try {
+            return Arrays.stream(FileSystemUtils.files(location))
+                .filter(path -> path.getFileName().toString().startsWith("_"))
+                .map(path -> path.getFileName().toString())
+                .map(this::getLocalSegmentFilename)
+                .collect(Collectors.toSet());
+        } catch (IOException exception) {
+            logger.error("Exception occurred while getting segment files", exception);
+        }
+        return Collections.emptySet();
+    }
+
+    private String getLocalSegmentFilename(String remoteFilename) {
+        return remoteFilename.split(RemoteSegmentStoreDirectory.SEGMENT_NAME_UUID_SEPARATOR)[0];
+    }
+
+    private IndexResponse indexSingleDoc() {
+        return client().prepareIndex(INDEX_NAME)
+            .setId(UUIDs.randomBase64UUID())
+            .setSource(randomAlphaOfLength(5), randomAlphaOfLength(5))
+            .get();
+    }
+
+    private void indexData(int numberOfIterations, boolean invokeFlush) {
+        logger.info("--> Indexing data for {} iterations with flush={}", numberOfIterations, invokeFlush);
+        for (int i = 0; i < numberOfIterations; i++) {
+            int numberOfOperations = randomIntBetween(1, 5);
+            logger.info("--> Indexing {} operations in iteration #{}", numberOfOperations, i);
+            for (int j = 0; j < numberOfOperations; j++) {
+                indexSingleDoc();
+            }
+            if (invokeFlush) {
+                flush(INDEX_NAME);
+            } else {
+                refresh(INDEX_NAME);
+            }
+        }
+    }
+}