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/*
* Copyright 2021 Johan Haleby
*
* Licensed 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.occurrent.subscription.mongodb.internal;
import org.bson.*;
import org.occurrent.subscription.StartAt;
import org.occurrent.subscription.StartAt.StartAtSubscriptionPosition;
import org.occurrent.subscription.StartAt.SubscriptionModelContext;
import org.occurrent.subscription.StringBasedSubscriptionPosition;
import org.occurrent.subscription.SubscriptionPosition;
import org.occurrent.subscription.mongodb.MongoOperationTimeSubscriptionPosition;
import org.occurrent.subscription.mongodb.MongoResumeTokenSubscriptionPosition;
import java.util.HashMap;
import java.util.Map;
import java.util.function.BiFunction;
public class MongoCommons {
public static final String RESUME_TOKEN = "resumeToken";
public static final String OPERATION_TIME = "operationTime";
public static final String GENERIC_SUBSCRIPTION_POSITION = "subscriptionPosition";
static final String RESUME_TOKEN_DATA = "_data";
public static final int CHANGE_STREAM_HISTORY_LOST_ERROR_CODE = 286;
public static Document generateResumeTokenStreamPositionDocument(String subscriptionId, BsonValue resumeToken) {
Map data = new HashMap<>();
data.put(MongoCloudEventsToJsonDeserializer.ID, subscriptionId);
data.put(RESUME_TOKEN, resumeToken);
return new Document(data);
}
public static Document generateOperationTimeStreamPositionDocument(String subscriptionId, BsonTimestamp operationTime) {
Map data = new HashMap<>();
data.put(MongoCloudEventsToJsonDeserializer.ID, subscriptionId);
data.put(OPERATION_TIME, operationTime);
return new Document(data);
}
public static Document generateGenericSubscriptionPositionDocument(String subscriptionId, String subscriptionPositionAsString) {
Map data = new HashMap<>();
data.put(MongoCloudEventsToJsonDeserializer.ID, subscriptionId);
data.put(GENERIC_SUBSCRIPTION_POSITION, subscriptionPositionAsString);
return new Document(data);
}
public static BsonTimestamp getServerOperationTime(Document hostInfoDocument) {
return getServerOperationTime(hostInfoDocument, 0);
}
public static BsonTimestamp getServerOperationTime(Document hostInfoDocument, int increaseIncrementBy) {
BsonTimestamp bsonTimestamp = (BsonTimestamp) hostInfoDocument.get(OPERATION_TIME);
return increaseIncrementBy > 0 ? new BsonTimestamp(bsonTimestamp.getTime(), bsonTimestamp.getInc() + increaseIncrementBy) : bsonTimestamp;
}
public static ResumeToken extractResumeTokenFromPersistedResumeTokenDocument(Document resumeTokenDocument) {
Document resumeTokenAsDocument = resumeTokenDocument.get(RESUME_TOKEN, Document.class);
BsonDocument resumeToken = new BsonDocument(RESUME_TOKEN_DATA, new BsonString(resumeTokenAsDocument.getString(RESUME_TOKEN_DATA)));
return new ResumeToken(resumeToken);
}
public static String cannotFindGlobalSubscriptionPositionErrorMessage(Throwable throwable) {
return "Failed to get global subscription position from MongoDB, probably because the server doesn't allow to execute the \"hostinfo\" command. " +
"This only affects the very first event received by the subscription. If the processing of this event fails _and_ the application is restarted " +
"the event cannot be retried. If this is major concern, consider upgrading your MongoDB server to a non-shared environment that supports the \"hostinfo\" command. Error is:\n" + throwable.getMessage();
}
public static BsonTimestamp extractOperationTimeFromPersistedPositionDocument(Document subscriptionPositionDocument) {
return subscriptionPositionDocument.get(OPERATION_TIME, BsonTimestamp.class);
}
public static T applyStartPosition(T t, BiFunction applyResumeToken, BiFunction applyOperationTime, StartAt startAt, SubscriptionModelContext ctx) {
StartAt startAtValue = startAt.get(ctx);
if (startAtValue.isNow() || startAtValue.isDefault()) {
return t;
} else if (!(startAtValue instanceof StartAtSubscriptionPosition)) {
throw new IllegalArgumentException("Unrecognized " + StartAt.class.getSimpleName() + " implementation: " + startAtValue.getClass().getName());
}
final T withStartPositionApplied;
StartAtSubscriptionPosition position = (StartAtSubscriptionPosition) startAtValue;
SubscriptionPosition changeStreamPosition = position.subscriptionPosition;
if (changeStreamPosition instanceof MongoResumeTokenSubscriptionPosition) {
BsonDocument resumeToken = ((MongoResumeTokenSubscriptionPosition) changeStreamPosition).resumeToken;
withStartPositionApplied = applyResumeToken.apply(t, resumeToken);
} else if (changeStreamPosition instanceof MongoOperationTimeSubscriptionPosition) {
withStartPositionApplied = applyOperationTime.apply(t, ((MongoOperationTimeSubscriptionPosition) changeStreamPosition).operationTime);
} else {
String changeStreamPositionString = changeStreamPosition.asString();
if (changeStreamPositionString.contains(RESUME_TOKEN)) {
BsonDocument bsonDocument = BsonDocument.parse(changeStreamPositionString);
BsonDocument resumeToken = bsonDocument.getDocument(RESUME_TOKEN);
withStartPositionApplied = applyResumeToken.apply(t, resumeToken);
} else if (changeStreamPositionString.contains(OPERATION_TIME)) {
Document document = Document.parse(changeStreamPositionString);
BsonTimestamp operationTime = document.get(OPERATION_TIME, BsonTimestamp.class);
withStartPositionApplied = applyOperationTime.apply(t, operationTime);
} else {
// We don't recognize the start position, but instead of throwing an exception we just start at "subscription model default"/now which
// means returning t. The reason for not throwing is that subscription models that wraps _this_ subscription (which doesn't understand the
// "changeStreamPositionString") may have custom understanding of the change stream position. For example, in the case of a CatchupSubscription,
// it adds a "TimeBasedSubscriptionPosition" which no other subscription model understands. In the case where the CatchupSubscription cannot get a global position,
// for example if we run on Atlas free-tier, it may write the "TimeBasedSubscriptionPosition" to the position storage impl. If no event has been received after
// the subscription has caught-up, the "TimeBasedSubscriptionPosition" will be retained in storage. If a restart happens before a new event has been received,
// then the CatchupSubscription will kick in again and understand the "TimeBasedSubscriptionPosition", thus preventing reading the events from the event store again.
return t;
}
}
return withStartPositionApplied;
}
public static SubscriptionPosition calculateSubscriptionPositionFromMongoStreamPositionDocument(Document subscriptionPositionDocument) {
final SubscriptionPosition changeStreamPosition;
if (subscriptionPositionDocument.containsKey(MongoCommons.RESUME_TOKEN)) {
ResumeToken resumeToken = MongoCommons.extractResumeTokenFromPersistedResumeTokenDocument(subscriptionPositionDocument);
changeStreamPosition = new MongoResumeTokenSubscriptionPosition(resumeToken.asBsonDocument());
} else if (subscriptionPositionDocument.containsKey(MongoCommons.OPERATION_TIME)) {
BsonTimestamp lastOperationTime = MongoCommons.extractOperationTimeFromPersistedPositionDocument(subscriptionPositionDocument);
changeStreamPosition = new MongoOperationTimeSubscriptionPosition(lastOperationTime);
} else if (subscriptionPositionDocument.containsKey(MongoCommons.GENERIC_SUBSCRIPTION_POSITION)) {
String value = subscriptionPositionDocument.getString(MongoCommons.GENERIC_SUBSCRIPTION_POSITION);
changeStreamPosition = new StringBasedSubscriptionPosition(value);
} else {
throw new IllegalStateException("Doesn't recognize " + subscriptionPositionDocument + " as a valid subscription position document");
}
return changeStreamPosition;
}
public static class ResumeToken {
private final BsonDocument resumeToken;
public ResumeToken(BsonDocument resumeToken) {
this.resumeToken = resumeToken;
}
public BsonDocument asBsonDocument() {
return resumeToken;
}
public String asString() {
return resumeToken.getString(RESUME_TOKEN_DATA).getValue();
}
}
}
