bitflicker64 commented on code in PR #3331: URL: https://github.com/apache/hugegraph/pull/3331#discussion_r4268028860
########## hugegraph-server/hugegraph-core/src/main/java/org/apache/hugegraph/LoadingMode.java: ########## @@ -0,0 +1,177 @@ +/* + * 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.hugegraph; + +import java.util.HashMap; +import java.util.Map; +import java.util.Objects; +import java.util.UUID; + +import org.apache.hugegraph.type.define.GraphMode; +import org.apache.hugegraph.util.E; +import org.apache.hugegraph.util.Log; +import org.slf4j.Logger; + +import com.google.common.collect.ImmutableMap; + +/** Same graph-instance ownership; this state is neither persisted nor distributed. */ +public final class LoadingMode { + + private static final Logger LOG = Log.logger(LoadingMode.class); + + private static final int MAX_RELEASED = 1024; + + private final String instance = UUID.randomUUID().toString(); + private final Map<String, String> active = new HashMap<>(); + private final Map<String, String> released = new HashMap<>(); + private long epoch; + private long revision; + private volatile GraphMode mode = GraphMode.NONE; + + public GraphMode mode() { + return this.mode; + } + + public synchronized void mode(GraphMode mode) { + Objects.requireNonNull(mode, "mode"); + checkState(this.active.isEmpty(), "Loading owners are active; release them before setting graph mode"); + if (this.mode != mode) { + this.advanceRevision(); + } + this.mode = mode; + } + + public synchronized Map<String, Object> capability() { + return ImmutableMap.of("protocol", 1, "instance", this.instance, "epoch", this.epoch, + "revision", this.revision); + } + + public synchronized Map<String, Object> recover(String instance, long epoch, long revision) { + E.checkArgument(this.instance.equals(instance), "Loading owner belongs to another graph instance"); + E.checkArgument(epoch >= 0 && revision >= 0, "Invalid loading recovery epoch or revision"); + checkState(epoch == this.epoch && revision == this.revision, + "Loading state changed; inspect it before recovery"); + checkState(this.epoch < Long.MAX_VALUE, "Loading owner epoch exhausted"); + GraphMode previousMode = this.mode; + int clearedOwners = this.active.size(); + this.advanceRevision(); + this.epoch++; + this.active.clear(); + this.released.clear(); + this.mode = GraphMode.NONE; + this.logChange("recover", previousMode, clearedOwners); + return ImmutableMap.<String, Object>builder().putAll(this.capability()) + .put("state", "recovered").put("mode", this.mode).build(); + } + + public synchronized Map<String, Object> update(String action, String instance, long epoch, + String token, String principal) { + E.checkArgument("acquire".equals(action) || "release".equals(action), + "Loading owner action must be acquire or release"); + E.checkArgument(this.instance.equals(instance), "Loading owner belongs to another graph instance"); + E.checkArgument(epoch >= 0 && epoch <= this.epoch, "Invalid loading owner epoch"); + E.checkArgument(token != null && token.length() == 36 && UUID.fromString(token).toString().equals(token), + "Loading owner token must be a canonical UUID"); + Objects.requireNonNull(principal, "principal"); + GraphMode previousMode = this.mode; + String key = epoch + "/" + token; + String owner = this.active.get(key); + if (owner != null) { + checkState(owner.equals(principal), "Loading owner belongs to another authenticated principal"); + if ("acquire".equals(action)) { + return this.receipt(epoch, token, "active"); + } + // Exhaustion must fail before changing an active registration. + checkState(epoch != this.epoch || this.released.size() < MAX_RELEASED || + this.epoch < Long.MAX_VALUE, "Loading owner epoch exhausted"); + this.advanceRevision(); + this.active.remove(key); + if (this.active.isEmpty()) { + this.mode = GraphMode.NONE; + } + } else if ("acquire".equals(action)) { + if (epoch < this.epoch || this.released.containsKey(key)) { + return this.receipt(epoch, token, "released"); + } + checkState(this.active.isEmpty() ? this.mode == GraphMode.NONE : this.mode == GraphMode.LOADING, + "Cannot acquire loading ownership of manually set graph mode %s", this.mode); + this.advanceRevision(); + this.active.put(key, principal); + this.mode = GraphMode.LOADING; + this.logChange("acquire", previousMode, 0); + return this.receipt(epoch, token, "active"); + } + // Unknown release cancels an acquire which may still be in transit. + if (epoch == this.epoch) { + String releasedOwner = this.released.get(key); + checkState(releasedOwner == null || releasedOwner.equals(principal), + "Loading owner belongs to another authenticated principal"); + if (releasedOwner != null) { + return this.receipt(epoch, token, "released"); + } + if (this.released.size() == MAX_RELEASED) { + checkState(this.epoch < Long.MAX_VALUE, "Loading owner epoch exhausted"); + if (owner == null) { + this.advanceRevision(); + } + this.epoch++; + this.released.clear(); + // Old nonactive tuples are terminal; active old tuples remain registered. + } else { + if (owner == null) { + this.advanceRevision(); + } + this.released.put(key, principal); + } + } + if (owner != null) { + this.logChange("release", previousMode, 1); + } + return this.receipt(epoch, token, "released"); + } + + private void logChange(String action, GraphMode previousMode, int clearedOwners) { + LOG.info("Loading ownership {} for graph instance {}: mode {} -> {}, epoch {}, " + Review Comment: Minor: the audit line names the graph only by `this.instance`, a random UUID made in the field initializer on line 39, so on a Server with several graphs the log does not say which graph went LOADING or was recovered. That UUID is exposed only through `GET .../mode/owners` on the live instance. After a graph reopen or a Server restart the old value cannot be mapped back to a graph, and that is when someone reads an audit trail. The enum path logs `Graph {} will work in {} mode` with `this`, which prints `spaceGraphName()`, so the two paths that change the mode are not logged the same way. Requested change: pass `spaceGraphName()` into `LoadingMode` (for example as a constructor argument from `StandardHugeGraph`) and add it to this message, or log the graph name with the instance UUID once when the graph opens. Extend the log assertions in `LoadingModeTest` to check it. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. 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