noblepaul commented on a change in pull request #2148: URL: https://github.com/apache/lucene-solr/pull/2148#discussion_r552362386
########## File path: solr/solrj/src/java/org/apache/solr/common/cloud/PerReplicaStates.java ########## @@ -0,0 +1,600 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.solr.common.cloud; + +import java.io.IOException; +import java.lang.invoke.MethodHandles; +import java.util.ArrayList; +import java.util.Collections; +import java.util.HashSet; +import java.util.LinkedHashMap; +import java.util.List; +import java.util.Map; +import java.util.Objects; +import java.util.Set; +import java.util.function.BiConsumer; + +import org.apache.solr.cluster.api.SimpleMap; +import org.apache.solr.common.MapWriter; +import org.apache.solr.common.SolrException; +import org.apache.solr.common.annotation.JsonProperty; +import org.apache.solr.common.util.ReflectMapWriter; +import org.apache.solr.common.util.StrUtils; +import org.apache.solr.common.util.WrappedSimpleMap; +import org.apache.zookeeper.CreateMode; +import org.apache.zookeeper.KeeperException; +import org.apache.zookeeper.Op; +import org.apache.zookeeper.data.ACL; +import org.apache.zookeeper.data.Stat; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import static java.util.Collections.singletonList; +import static org.apache.solr.common.params.CommonParams.NAME; +import static org.apache.solr.common.params.CommonParams.VERSION; + +/** + * This represents the individual replica states in a collection + * This is an immutable object. When states are modified, a new instance is constructed + */ +public class PerReplicaStates implements ReflectMapWriter { + private static final Logger log = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass()); + public static final char SEPARATOR = ':'; + + + @JsonProperty + public final String path; + + @JsonProperty + public final int cversion; + + @JsonProperty + public final SimpleMap<State> states; + + /** + * Construct with data read from ZK + * @param path path from where this is loaded + * @param cversion the current child version of the znode + * @param states the per-replica states (the list of all child nodes) + */ + public PerReplicaStates(String path, int cversion, List<String> states) { + this.path = path; + this.cversion = cversion; + Map<String, State> tmp = new LinkedHashMap<>(); + + for (String state : states) { + State rs = State.parse(state); + if (rs == null) continue; + State existing = tmp.get(rs.replica); + if (existing == null) { + tmp.put(rs.replica, rs); + } else { + tmp.put(rs.replica, rs.insert(existing)); + } + } + this.states = new WrappedSimpleMap<>(tmp); + + } + + /**Get the changed replicas + */ + public static Set<String> findModifiedReplicas(PerReplicaStates old, PerReplicaStates fresh) { + Set<String> result = new HashSet<>(); + if (fresh == null) { + old.states.forEachKey(result::add); + return result; + } + old.states.forEachEntry((s, state) -> { + // the state is modified or missing + if (!Objects.equals(fresh.get(s) , state)) result.add(s); + }); + fresh.states.forEachEntry((s, state) -> { if (old.get(s) == null ) result.add(s); + }); + return result; + } + + /** + * This is a persist operation with retry if a write fails due to stale state + */ + public static void persist(WriteOps ops, String znode, SolrZkClient zkClient) throws KeeperException, InterruptedException { + List<Operation> operations = ops.get(); + for (int i = 0; i < 10; i++) { + try { + persist(operations, znode, zkClient); + return; + } catch (KeeperException.NodeExistsException | KeeperException.NoNodeException e) { + //state is stale + log.info("stale state for {}. retrying...", znode); + operations = ops.get(PerReplicaStates.fetch(znode, zkClient, null)); + } + } + } + + /** + * Persist a set of operations to Zookeeper + */ + public static void persist(List<Operation> operations, String znode, SolrZkClient zkClient) throws KeeperException, InterruptedException { + if (operations == null || operations.isEmpty()) return; + log.debug("Per-replica state being persisted for :{}, ops: {}", znode, operations); + + List<Op> ops = new ArrayList<>(operations.size()); + for (Operation op : operations) { + //the state of the replica is being updated + String path = znode + "/" + op.state.asString; + List<ACL> acls = zkClient.getZkACLProvider().getACLsToAdd(path); + ops.add(op.typ == Operation.Type.ADD ? + Op.create(path, null, acls, CreateMode.PERSISTENT) : + Op.delete(path, -1)); + } + try { + zkClient.multi(ops, true); + if (log.isDebugEnabled()) { + //nocommit + try { + Stat stat = zkClient.exists(znode, null, true); + log.debug("After update, cversion : {}", stat.getCversion()); + } catch (Exception e) { + } + + } + } catch (KeeperException e) { + log.error("multi op exception : " + e.getMessage() + zkClient.getChildren(znode, null, true)); + throw e; + } + + } + + + /** + * Fetch the latest {@link PerReplicaStates} . It fetches data after checking the {@link Stat#getCversion()} of state.json. + * If this is not modified, the same object is returned + */ + public static PerReplicaStates fetch(String path, SolrZkClient zkClient, PerReplicaStates current) { + try { + if (current != null) { + Stat stat = zkClient.exists(current.path, null, true); + if (stat == null) return new PerReplicaStates(path, -1, Collections.emptyList()); + if (current.cversion == stat.getCversion()) return current;// not modifiedZkStateReaderTest + } + Stat stat = new Stat(); + List<String> children = zkClient.getChildren(path, null, stat, true); + return new PerReplicaStates(path, stat.getCversion(), Collections.unmodifiableList(children)); + } catch (KeeperException e) { + throw new SolrException(SolrException.ErrorCode.SERVER_ERROR, "Error fetching per-replica states", e); + } catch (InterruptedException e) { + SolrZkClient.checkInterrupted(e); + throw new SolrException(SolrException.ErrorCode.SERVER_ERROR, "Thread interrupted when loading per-replica states from " + path, e); + } + } + + + private static List<Operation> addDeleteStaleNodes(List<Operation> ops, State rs) { + while (rs != null) { + ops.add(new Operation(Operation.Type.DELETE, rs)); + rs = rs.duplicate; + } + return ops; + } + + public static String getReplicaName(String s) { + int idx = s.indexOf(SEPARATOR); + if (idx > 0) { + return s.substring(0, idx); + } + return null; + } + + public State get(String replica) { + return states.get(replica); + } + + public static class Operation { + public final Type typ; + public final State state; + + public Operation(Type typ, State replicaState) { + this.typ = typ; + this.state = replicaState; + } + + + public enum Type { + //add a new node + ADD, + //delete an existing node + DELETE + } + + @Override + public String toString() { + return typ.toString() + " : " + state; + } + } + + + /** + * The state of a replica as stored as a node under /collections/collection-name/state.json/replica-state + */ + public static class State implements MapWriter { + + public final String replica; + + public final Replica.State state; + + public final Boolean isLeader; + + public final int version; + + public final String asString; + + /** + * if there are multiple entries for the same replica, e.g: core_node_1:12:A core_node_1:13:D + * <p> + * the entry with '13' is the latest and the one with '12' is considered a duplicate + * <p> + * These are unlikely, but possible + */ + final State duplicate; + + private State(String serialized, List<String> pieces) { + this.asString = serialized; + replica = pieces.get(0); + version = Integer.parseInt(pieces.get(1)); + String encodedStatus = pieces.get(2); + this.state = Replica.getState(encodedStatus); + isLeader = pieces.size() > 3 && "L".equals(pieces.get(3)); + duplicate = null; + } + + public static State parse(String serialized) { + List<String> pieces = StrUtils.splitSmart(serialized, ':'); + if (pieces.size() < 3) return null; + return new State(serialized, pieces); + + } + + public State(String replica, Replica.State state, Boolean isLeader, int version) { + this(replica, state, isLeader, version, null); + } + + public State(String replica, Replica.State state, Boolean isLeader, int version, State duplicate) { + this.replica = replica; + this.state = state == null ? Replica.State.ACTIVE : state; + this.isLeader = isLeader == null ? Boolean.FALSE : isLeader; + this.version = version; + asString = serialize(); + this.duplicate = duplicate; + } + + @Override + public void writeMap(EntryWriter ew) throws IOException { + ew.put(NAME, replica); + ew.put(VERSION, version); + ew.put(ZkStateReader.STATE_PROP, state.toString()); + if (isLeader) ew.put(Slice.LEADER, isLeader); + ew.putIfNotNull("duplicate", duplicate); + } + + private State insert(State duplicate) { + assert this.replica.equals(duplicate.replica); + if (this.version >= duplicate.version) { + if (this.duplicate != null) { + duplicate = new State(duplicate.replica, duplicate.state, duplicate.isLeader, duplicate.version, this.duplicate); + } + return new State(this.replica, this.state, this.isLeader, this.version, duplicate); + } else { + return duplicate.insert(this); + } + } + + /** + * fetch duplicates entries for this replica + */ + List<State> getDuplicates() { + if (duplicate == null) return Collections.emptyList(); + List<State> result = new ArrayList<>(); + State current = duplicate; + while (current != null) { + result.add(current); + current = current.duplicate; + } + return result; + } + + private String serialize() { + StringBuilder sb = new StringBuilder(replica) + .append(":") + .append(version) + .append(":") + .append(state.shortName); + if (isLeader) sb.append(":").append("L"); + return sb.toString(); + } + + + @Override + public String toString() { + return asString; + } + + @Override + public boolean equals(Object o) { + if (o instanceof State) { + State that = (State) o; + return Objects.equals(this.asString, that.asString); + } + return false; + } + + @Override + public int hashCode() { + return asString.hashCode(); + } + } + + + /**This is a helper class that encapsulates various operations performed on the per-replica states + * Do not directly manipulate the per replica states as it can become difficult to debug them + * + */ + public static abstract class WriteOps { + private PerReplicaStates rs; + List<Operation> ops; + private boolean preOp = true; + + /** + * state of a replica is changed + * + * @param newState the new state + */ + public static WriteOps flipState(String replica, Replica.State newState, PerReplicaStates rs) { + return new WriteOps() { + @Override + protected List<Operation> refresh(PerReplicaStates rs) { + List<Operation> ops = new ArrayList<>(2); + State existing = rs.get(replica); + if (existing == null) { + ops.add(new Operation(Operation.Type.ADD, new State(replica, newState, Boolean.FALSE, 0))); + } else { + ops.add(new Operation(Operation.Type.ADD, new State(replica, newState, existing.isLeader, existing.version + 1))); + addDeleteStaleNodes(ops, existing); + } + if (log.isDebugEnabled()) { + log.debug("flipState on {}, {} -> {}, ops :{}", rs.path, replica, newState, ops); + } + return ops; + } + }.init(rs); + } + + public PerReplicaStates getPerReplicaStates() { + return rs; + } + + + /**Switch a collection from/to perReplicaState=true + */ + public static WriteOps modifyCollection(DocCollection coll, boolean enable, PerReplicaStates prs) { + return new WriteOps() { + @Override + List<Operation> refresh(PerReplicaStates prs) { + return enable ? enable(coll) : disable(prs); Review comment: yeah , disable just blindly deletes everything ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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