Remove Version 6 pre-release constants (#41517)

Now that master is 8.0, we can remove uses of these constants and the
backcompat code that uses them, since 8 will always walk to 7.0+ nodes.
This PR starts by removing the pre-6 release constants, remove obsolete code
and replacing its occurances in tests where needed.

Relates to #41164

Author: Christoph Büscher

server/src/main/java/org/elasticsearch/Version.java

@@ -46,24 +46,6 @@ public class Version implements Comparable<Version>, ToXContentFragment {
      */
     public static final int V_EMPTY_ID = 0;
     public static final Version V_EMPTY = new Version(V_EMPTY_ID, org.apache.lucene.util.Version.LATEST);
-    public static final int V_6_0_0_alpha1_ID = 6000001;
-    public static final Version V_6_0_0_alpha1 =
-            new Version(V_6_0_0_alpha1_ID, org.apache.lucene.util.Version.LUCENE_7_0_0);
-    public static final int V_6_0_0_alpha2_ID = 6000002;
-    public static final Version V_6_0_0_alpha2 =
-            new Version(V_6_0_0_alpha2_ID, org.apache.lucene.util.Version.LUCENE_7_0_0);
-    public static final int V_6_0_0_beta1_ID = 6000026;
-    public static final Version V_6_0_0_beta1 =
-        new Version(V_6_0_0_beta1_ID, org.apache.lucene.util.Version.LUCENE_7_0_0);
-    public static final int V_6_0_0_beta2_ID = 6000027;
-    public static final Version V_6_0_0_beta2 =
-        new Version(V_6_0_0_beta2_ID, org.apache.lucene.util.Version.LUCENE_7_0_0);
-    public static final int V_6_0_0_rc1_ID = 6000051;
-    public static final Version V_6_0_0_rc1 =
-        new Version(V_6_0_0_rc1_ID, org.apache.lucene.util.Version.LUCENE_7_0_0);
-    public static final int V_6_0_0_rc2_ID = 6000052;
-    public static final Version V_6_0_0_rc2 =
-        new Version(V_6_0_0_rc2_ID, org.apache.lucene.util.Version.LUCENE_7_0_1);
     public static final int V_6_0_0_ID = 6000099;
     public static final Version V_6_0_0 =
         new Version(V_6_0_0_ID, org.apache.lucene.util.Version.LUCENE_7_0_1);
@@ -234,18 +216,6 @@ public static Version fromId(int id) {
                 return V_6_0_1;
             case V_6_0_0_ID:
                 return V_6_0_0;
-            case V_6_0_0_rc2_ID:
-                return V_6_0_0_rc2;
-            case V_6_0_0_beta2_ID:
-                return V_6_0_0_beta2;
-            case V_6_0_0_rc1_ID:
-                return V_6_0_0_rc1;
-            case V_6_0_0_beta1_ID:
-                return V_6_0_0_beta1;
-            case V_6_0_0_alpha2_ID:
-                return V_6_0_0_alpha2;
-            case V_6_0_0_alpha1_ID:
-                return V_6_0_0_alpha1;
             case V_EMPTY_ID:
                 return V_EMPTY;
             default:
@@ -445,7 +415,7 @@ public Version minimumCompatibilityVersion() {
             return bwcVersion == null ? this : bwcVersion;
         }
 
-        return Version.min(this, fromId((int) major * 1000000 + 0 * 10000 + 99));
+        return Version.min(this, fromId(major * 1000000 + 0 * 10000 + 99));
     }
 
     /**
@@ -457,8 +427,6 @@ public Version minimumIndexCompatibilityVersion() {
         final int bwcMajor;
         if (major == 5) {
             bwcMajor = 2; // we jumped from 2 to 5
-        } else if (major == 7) {
-            return V_6_0_0_beta1;
         } else {
             bwcMajor = major - 1;
         }

server/src/main/java/org/elasticsearch/cluster/metadata/MetaDataCreateIndexService.java

@@ -20,8 +20,9 @@
 package org.elasticsearch.cluster.metadata;
 
 import com.carrotsearch.hppc.cursors.ObjectObjectCursor;
-import org.apache.logging.log4j.Logger;
+
 import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
 import org.apache.logging.log4j.message.ParameterizedMessage;
 import org.elasticsearch.ElasticsearchException;
 import org.elasticsearch.ResourceAlreadyExistsException;
@@ -714,13 +715,6 @@ static void validateSplitIndex(ClusterState state, String sourceIndex,
                                    Settings targetIndexSettings) {
         IndexMetaData sourceMetaData = validateResize(state, sourceIndex, targetIndexMappingsTypes, targetIndexName, targetIndexSettings);
         IndexMetaData.selectSplitShard(0, sourceMetaData, IndexMetaData.INDEX_NUMBER_OF_SHARDS_SETTING.get(targetIndexSettings));
-        if (sourceMetaData.getCreationVersion().before(Version.V_6_0_0_alpha1)) {
-            // ensure we have a single type since this would make the splitting code considerably more complex
-            // and a 5.x index would not be splittable unless it has been shrunk before so rather opt out of the complexity
-            // since in 5.x we don't have a setting to artificially set the number of routing shards
-            throw new IllegalStateException("source index created version is too old to apply a split operation");
-        }
-
     }
 
     static IndexMetaData validateResize(ClusterState state, String sourceIndex,

server/src/main/java/org/elasticsearch/cluster/routing/OperationRouting.java

@@ -19,7 +19,6 @@
 
 package org.elasticsearch.cluster.routing;
 
-import org.elasticsearch.Version;
 import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.cluster.metadata.IndexMetaData;
 import org.elasticsearch.cluster.node.DiscoveryNodes;
@@ -194,16 +193,7 @@ private ShardIterator preferenceActiveShardIterator(IndexShardRoutingTable index
             }
         }
         // if not, then use it as the index
-        int routingHash = Murmur3HashFunction.hash(preference);
-        if (nodes.getMinNodeVersion().onOrAfter(Version.V_6_0_0_alpha1)) {
-            // The AllocationService lists shards in a fixed order based on nodes
-            // so earlier versions of this class would have a tendency to
-            // select the same node across different shardIds.
-            // Better overall balancing can be achieved if each shardId opts
-            // for a different element in the list by also incorporating the
-            // shard ID into the hash of the user-supplied preference key.
-            routingHash = 31 * routingHash + indexShard.shardId.hashCode();
-        }
+        int routingHash = 31 * Murmur3HashFunction.hash(preference) + indexShard.shardId.hashCode();
         if (awarenessAttributes.isEmpty()) {
             return indexShard.activeInitializingShardsIt(routingHash);
         } else {

server/src/main/java/org/elasticsearch/index/IndexSortConfig.java

@@ -23,7 +23,6 @@
 import org.apache.lucene.search.SortField;
 import org.apache.lucene.search.SortedNumericSortField;
 import org.apache.lucene.search.SortedSetSortField;
-import org.elasticsearch.Version;
 import org.elasticsearch.common.settings.Setting;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.index.fielddata.IndexFieldData;
@@ -120,15 +119,6 @@ public IndexSortConfig(IndexSettings indexSettings) {
             .map((name) -> new FieldSortSpec(name))
             .toArray(FieldSortSpec[]::new);
 
-        if (sortSpecs.length > 0 && indexSettings.getIndexVersionCreated().before(Version.V_6_0_0_alpha1)) {
-            /**
-             * This index might be assigned to a node where the index sorting feature is not available
-             * (ie. versions prior to {@link Version.V_6_0_0_alpha1_UNRELEASED}) so we must fail here rather than later.
-             */
-            throw new IllegalArgumentException("unsupported index.version.created:" + indexSettings.getIndexVersionCreated() +
-                ", can't set index.sort on versions prior to " + Version.V_6_0_0_alpha1);
-        }
-
         if (INDEX_SORT_ORDER_SETTING.exists(settings)) {
             List<SortOrder> orders = INDEX_SORT_ORDER_SETTING.get(settings);
             if (orders.size() != sortSpecs.length) {

server/src/main/java/org/elasticsearch/index/mapper/DynamicTemplate.java

@@ -202,19 +202,7 @@ public static DynamicTemplate parse(String name, Map<String, Object> conf,
 
         XContentFieldType xcontentFieldType = null;
         if (matchMappingType != null && matchMappingType.equals("*") == false) {
-            try {
-                xcontentFieldType = XContentFieldType.fromString(matchMappingType);
-            } catch (IllegalArgumentException e) {
-                if (indexVersionCreated.onOrAfter(Version.V_6_0_0_alpha1)) {
-                    throw e;
-                } else {
-                    deprecationLogger.deprecated("match_mapping_type [" + matchMappingType + "] is invalid and will be ignored: "
-                            + e.getMessage());
-                    // this template is on an unknown type so it will never match anything
-                    // null indicates that the template should be ignored
-                    return null;
-                }
-            }
+            xcontentFieldType = XContentFieldType.fromString(matchMappingType);
         }
 
         final MatchType matchType = MatchType.fromString(matchPattern);

server/src/main/java/org/elasticsearch/index/seqno/ReplicationTracker.java

@@ -21,6 +21,7 @@
 
 import com.carrotsearch.hppc.ObjectLongHashMap;
 import com.carrotsearch.hppc.ObjectLongMap;
+
 import org.elasticsearch.Version;
 import org.elasticsearch.action.ActionListener;
 import org.elasticsearch.action.support.replication.ReplicationResponse;
@@ -758,10 +759,9 @@ public synchronized void activatePrimaryMode(final long localCheckpoint) {
      * @param applyingClusterStateVersion the cluster state version being applied when updating the allocation IDs from the master
      * @param inSyncAllocationIds         the allocation IDs of the currently in-sync shard copies
      * @param routingTable                the shard routing table
-     * @param pre60AllocationIds          the allocation IDs of shards that are allocated to pre-6.0 nodes
      */
     public synchronized void updateFromMaster(final long applyingClusterStateVersion, final Set<String> inSyncAllocationIds,
-                                              final IndexShardRoutingTable routingTable, final Set<String> pre60AllocationIds) {
+                                              final IndexShardRoutingTable routingTable) {
         assert invariant();
         if (applyingClusterStateVersion > appliedClusterStateVersion) {
             // check that the master does not fabricate new in-sync entries out of thin air once we are in primary mode
@@ -782,8 +782,7 @@ public synchronized void updateFromMaster(final long applyingClusterStateVersion
                         final boolean inSync = inSyncAllocationIds.contains(initializingId);
                         assert inSync == false : "update from master in primary mode has " + initializingId +
                             " as in-sync but it does not exist locally";
-                        final long localCheckpoint = pre60AllocationIds.contains(initializingId) ?
-                            SequenceNumbers.PRE_60_NODE_CHECKPOINT : SequenceNumbers.UNASSIGNED_SEQ_NO;
+                        final long localCheckpoint = SequenceNumbers.UNASSIGNED_SEQ_NO;
                         final long globalCheckpoint = localCheckpoint;
                         checkpoints.put(initializingId, new CheckpointState(localCheckpoint, globalCheckpoint, inSync, inSync));
                     }
@@ -794,8 +793,7 @@ public synchronized void updateFromMaster(final long applyingClusterStateVersion
             } else {
                 for (String initializingId : initializingAllocationIds) {
                     if (shardAllocationId.equals(initializingId) == false) {
-                        final long localCheckpoint = pre60AllocationIds.contains(initializingId) ?
-                            SequenceNumbers.PRE_60_NODE_CHECKPOINT : SequenceNumbers.UNASSIGNED_SEQ_NO;
+                        final long localCheckpoint = SequenceNumbers.UNASSIGNED_SEQ_NO;
                         final long globalCheckpoint = localCheckpoint;
                         checkpoints.put(initializingId, new CheckpointState(localCheckpoint, globalCheckpoint, false, false));
                     }
@@ -807,8 +805,7 @@ public synchronized void updateFromMaster(final long applyingClusterStateVersion
                         checkpointState.inSync = true;
                         checkpointState.tracked = true;
                     } else {
-                        final long localCheckpoint = pre60AllocationIds.contains(inSyncId) ?
-                            SequenceNumbers.PRE_60_NODE_CHECKPOINT : SequenceNumbers.UNASSIGNED_SEQ_NO;
+                        final long localCheckpoint = SequenceNumbers.UNASSIGNED_SEQ_NO;
                         final long globalCheckpoint = localCheckpoint;
                         checkpoints.put(inSyncId, new CheckpointState(localCheckpoint, globalCheckpoint, true, true));
                     }
@@ -1082,17 +1079,13 @@ private Runnable getMasterUpdateOperationFromCurrentState() {
         assert primaryMode == false;
         final long lastAppliedClusterStateVersion = appliedClusterStateVersion;
         final Set<String> inSyncAllocationIds = new HashSet<>();
-        final Set<String> pre60AllocationIds = new HashSet<>();
         checkpoints.entrySet().forEach(entry -> {
             if (entry.getValue().inSync) {
                 inSyncAllocationIds.add(entry.getKey());
             }
-            if (entry.getValue().getLocalCheckpoint() == SequenceNumbers.PRE_60_NODE_CHECKPOINT) {
-                pre60AllocationIds.add(entry.getKey());
-            }
         });
         final IndexShardRoutingTable lastAppliedRoutingTable = routingTable;
-        return () -> updateFromMaster(lastAppliedClusterStateVersion, inSyncAllocationIds, lastAppliedRoutingTable, pre60AllocationIds);
+        return () -> updateFromMaster(lastAppliedClusterStateVersion, inSyncAllocationIds, lastAppliedRoutingTable);
     }
 
     /**

server/src/main/java/org/elasticsearch/index/shard/IndexShard.java

@@ -20,6 +20,7 @@
 package org.elasticsearch.index.shard;
 
 import com.carrotsearch.hppc.ObjectLongMap;
+
 import org.apache.logging.log4j.Logger;
 import org.apache.logging.log4j.message.ParameterizedMessage;
 import org.apache.lucene.index.CheckIndex;
@@ -433,8 +434,7 @@ public void updateShardState(final ShardRouting newRouting,
                                  final BiConsumer<IndexShard, ActionListener<ResyncTask>> primaryReplicaSyncer,
                                  final long applyingClusterStateVersion,
                                  final Set<String> inSyncAllocationIds,
-                                 final IndexShardRoutingTable routingTable,
-                                 final Set<String> pre60AllocationIds) throws IOException {
+                                 final IndexShardRoutingTable routingTable) throws IOException {
         final ShardRouting currentRouting;
         synchronized (mutex) {
             currentRouting = this.shardRouting;
@@ -453,7 +453,7 @@ public void updateShardState(final ShardRouting newRouting,
             }
 
             if (newRouting.primary()) {
-                replicationTracker.updateFromMaster(applyingClusterStateVersion, inSyncAllocationIds, routingTable, pre60AllocationIds);
+                replicationTracker.updateFromMaster(applyingClusterStateVersion, inSyncAllocationIds, routingTable);
             }
 
             if (state == IndexShardState.POST_RECOVERY && newRouting.active()) {

server/src/main/java/org/elasticsearch/index/shard/ShardSplittingQuery.java

@@ -65,10 +65,6 @@ final class ShardSplittingQuery extends Query {
     private final BitSetProducer nestedParentBitSetProducer;
 
     ShardSplittingQuery(IndexMetaData indexMetaData, int shardId, boolean hasNested) {
-        if (indexMetaData.getCreationVersion().before(Version.V_6_0_0_rc2)) {
-            throw new IllegalArgumentException("Splitting query can only be executed on an index created with version "
-                + Version.V_6_0_0_rc2 + " or higher");
-        }
         this.indexMetaData = indexMetaData;
         this.shardId = shardId;
         this.nestedParentBitSetProducer =  hasNested ? newParentDocBitSetProducer(indexMetaData.getCreationVersion()) : null;

server/src/main/java/org/elasticsearch/index/shard/StoreRecovery.java

@@ -20,6 +20,7 @@
 package org.elasticsearch.index.shard;
 
 import com.carrotsearch.hppc.cursors.ObjectObjectCursor;
+
 import org.apache.logging.log4j.Logger;
 import org.apache.lucene.index.IndexWriter;
 import org.apache.lucene.index.IndexWriterConfig;
@@ -31,7 +32,6 @@
 import org.apache.lucene.store.IOContext;
 import org.apache.lucene.store.IndexInput;
 import org.elasticsearch.ExceptionsHelper;
-import org.elasticsearch.Version;
 import org.elasticsearch.cluster.metadata.IndexMetaData;
 import org.elasticsearch.cluster.metadata.MappingMetaData;
 import org.elasticsearch.cluster.routing.RecoverySource;
@@ -119,8 +119,6 @@ boolean recoverFromLocalShards(BiConsumer<String, MappingMetaData> mappingUpdate
             Sort indexSort = indexShard.getIndexSort();
             final boolean hasNested = indexShard.mapperService().hasNested();
             final boolean isSplit = sourceMetaData.getNumberOfShards() < indexShard.indexSettings().getNumberOfShards();
-            assert isSplit == false || sourceMetaData.getCreationVersion().onOrAfter(Version.V_6_0_0_alpha1) : "for split we require a " +
-                "single type but the index is created before 6.0.0";
             return executeRecovery(indexShard, () -> {
                 logger.debug("starting recovery from local shards {}", shards);
                 try {

server/src/main/java/org/elasticsearch/index/translog/Translog.java

@@ -22,7 +22,6 @@
 import org.apache.logging.log4j.message.ParameterizedMessage;
 import org.apache.lucene.index.Term;
 import org.apache.lucene.store.AlreadyClosedException;
-import org.elasticsearch.Version;
 import org.elasticsearch.common.UUIDs;
 import org.elasticsearch.common.bytes.BytesArray;
 import org.elasticsearch.common.bytes.BytesReference;
@@ -216,15 +215,8 @@ private ArrayList<TranslogReader> recoverFromFiles(Checkpoint checkpoint) throws
         try (ReleasableLock lock = writeLock.acquire()) {
             logger.debug("open uncommitted translog checkpoint {}", checkpoint);
 
-            final long minGenerationToRecoverFrom;
-            if (checkpoint.minTranslogGeneration < 0) {
-                final Version indexVersionCreated = indexSettings().getIndexVersionCreated();
-                assert indexVersionCreated.before(Version.V_6_0_0_beta1) :
-                    "no minTranslogGeneration in checkpoint, but index was created with version [" + indexVersionCreated + "]";
-                minGenerationToRecoverFrom = deletionPolicy.getMinTranslogGenerationForRecovery();
-            } else {
-                minGenerationToRecoverFrom = checkpoint.minTranslogGeneration;
-            }
+            final long minGenerationToRecoverFrom = checkpoint.minTranslogGeneration;
+            assert minGenerationToRecoverFrom >= 0 : "minTranslogGeneration should be non-negative";
 
             final String checkpointTranslogFile = getFilename(checkpoint.generation);
             // we open files in reverse order in order to validate tranlsog uuid before we start traversing the translog based on
@@ -882,6 +874,7 @@ public Location(long generation, long translogLocation, int size) {
             this.size = size;
         }
 
+        @Override
         public String toString() {
             return "[generation: " + generation + ", location: " + translogLocation + ", size: " + size + "]";
         }