io.vertx.spi.cluster.consul.impl.ConsulAsyncMap Maven / Gradle / Ivy
/*
* Copyright (C) 2018-2019 Roman Levytskyi
*
* 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 io.vertx.spi.cluster.consul.impl;
import io.vertx.core.*;
import io.vertx.core.logging.Logger;
import io.vertx.core.logging.LoggerFactory;
import io.vertx.core.shareddata.AsyncMap;
import io.vertx.core.shareddata.LocalMap;
import io.vertx.core.shareddata.Lock;
import io.vertx.core.spi.cluster.ClusterManager;
import io.vertx.ext.consul.KeyValueOptions;
import java.util.*;
import static io.vertx.core.Future.failedFuture;
import static io.vertx.core.Future.succeededFuture;
import static io.vertx.spi.cluster.consul.impl.ConversationUtils.asFutureString;
import static io.vertx.spi.cluster.consul.impl.ConversationUtils.asTtlConsulEntry;
/**
* Distributed async map implementation that is backed by consul key-value store.
*
* Note: given map is used by vertx nodes to share the data,
* entries of this map are always PERSISTENT and NOT EPHEMERAL.
*
* For ttl handling see {@link TTLMonitor}
*
* @author Roman Levytskyi
*/
public class ConsulAsyncMap extends ConsulMap implements AsyncMap {
private static final Logger log = LoggerFactory.getLogger(ConsulAsyncMap.class);
private final TTLMonitor ttlMonitor;
public ConsulAsyncMap(String name, ClusterManagerInternalContext appContext, ClusterManager clusterManager) {
super(name, appContext);
this.ttlMonitor = new TTLMonitor(appContext.getVertx(), clusterManager, name, appContext.getNodeId());
startListening();
}
@Override
public void get(K k, Handler> asyncResultHandler) {
assertKeyIsNotNull(k)
.compose(aVoid -> getValue(k))
.setHandler(asyncResultHandler);
}
@Override
public void put(K k, V v, Handler> completionHandler) {
assertKeyAndValueAreNotNull(k, v)
.compose(aVoid -> putValue(k, v, null, Optional.empty()))
.compose(putSucceeded -> putSucceeded ? Future.succeededFuture() : failedFuture(k.toString() + "wasn't put to: " + name))
.setHandler(completionHandler);
}
@Override
public void put(K k, V v, long ttl, Handler> completionHandler) {
assertKeyAndValueAreNotNull(k, v)
.compose(id -> putValue(k, v, null, Optional.of(ttl)))
.compose(putSucceeded -> putSucceeded ? succeededFuture() : Future.failedFuture(k.toString() + "wasn't put to " + name))
.setHandler(completionHandler);
}
@Override
public void putIfAbsent(K k, V v, Handler> completionHandler) {
putIfAbsent(k, v, Optional.empty()).setHandler(completionHandler);
}
@Override
public void putIfAbsent(K k, V v, long ttl, Handler> completionHandler) {
assertKeyAndValueAreNotNull(k, v)
.compose(aVoid -> putIfAbsent(k, v, Optional.of(ttl)))
.setHandler(completionHandler);
}
@Override
public void remove(K k, Handler> asyncResultHandler) {
assertKeyIsNotNull(k).compose(aVoid -> {
Promise promise = Promise.promise();
get(k, promise);
return promise.future();
}).compose(v -> {
Promise promise = Promise.promise();
if (v == null) promise.complete();
else deleteValueByKeyPath(keyPath(k))
.compose(removeSucceeded -> removeSucceeded ? succeededFuture(v) : failedFuture("Key + " + k + " wasn't removed."))
.setHandler(promise);
return promise.future();
}).setHandler(asyncResultHandler);
}
@Override
public void removeIfPresent(K k, V v, Handler> resultHandler) {
// removes a value from the map, only if entry already exists with same value.
assertKeyAndValueAreNotNull(k, v).compose(aVoid -> {
Promise promise = Promise.promise();
get(k, promise);
return promise.future();
}).compose(value -> {
if (v.equals(value))
return deleteValueByKeyPath(keyPath(k))
.compose(removeSucceeded -> removeSucceeded ? succeededFuture(true) : failedFuture("Key + " + k + " wasn't removed."));
else return succeededFuture(false);
}).setHandler(resultHandler);
}
@Override
public void replace(K k, V v, Handler> asyncResultHandler) {
// replaces the entry only if it is currently mapped to some value.
assertKeyAndValueAreNotNull(k, v).compose(aVoid -> {
Promise promise = Promise.promise();
get(k, promise);
return promise.future();
}).compose(value -> {
Promise promise = Promise.promise();
if (value == null) {
promise.complete();
} else {
put(k, v, event -> {
if (event.succeeded()) promise.complete(value);
else promise.fail(event.cause());
});
}
return promise.future();
}).setHandler(asyncResultHandler);
}
@Override
public void replaceIfPresent(K k, V oldValue, V newValue, Handler> resultHandler) {
// replaces the entry only if it is currently mapped to a specific value.
assertKeyAndValueAreNotNull(k, oldValue)
.compose(aVoid -> assertValueIsNotNull(newValue))
.compose(aVoid -> {
Promise promise = Promise.promise();
get(k, promise);
return promise.future();
})
.compose(value -> {
Promise promise = Promise.promise();
if (value != null) {
if (value.equals(oldValue))
put(k, newValue, resultPutHandler -> {
if (resultPutHandler.succeeded())
promise.complete(true); // old V: '{}' has been replaced by new V: '{}' where K: '{}'", oldValue, newValue, k
else
promise.fail(resultPutHandler.cause()); // failed replace old V: '{}' by new V: '{}' where K: '{}' due to: '{}'", oldValue, newValue, k, resultPutHandler.cause()
});
else
promise.complete(false); // "An entry with K: '{}' doesn't map to old V: '{}' so it won't get replaced.", k, oldValue);
} else promise.complete(false); // An entry with K: '{}' doesn't exist,
return promise.future();
})
.setHandler(resultHandler);
}
@Override
public void clear(Handler> resultHandler) {
deleteAll().setHandler(resultHandler);
}
@Override
public void size(Handler> resultHandler) {
plainKeys().compose(list -> succeededFuture(list.size())).setHandler(resultHandler);
}
@Override
public void keys(Handler>> asyncResultHandler) {
entries().compose(kvMap -> succeededFuture(kvMap.keySet())).setHandler(asyncResultHandler);
}
@Override
public void values(Handler>> asyncResultHandler) {
entries().compose(kvMap -> Future.>succeededFuture(new ArrayList<>(kvMap.values())).setHandler(asyncResultHandler));
}
@Override
public void entries(Handler>> asyncResultHandler) {
entries().setHandler(asyncResultHandler);
}
@Override
protected void entryUpdated(EntryEvent event) {
if (event.getEventType() == EntryEvent.EventType.WRITE) {
if (log.isDebugEnabled()) {
log.debug("[" + appContext.getNodeId() + "] : " + "applying a ttl monitor on entry: " + event.getEntry().getKey());
}
ttlMonitor.apply(
event.getEntry().getKey(),
asTtlConsulEntry(event.getEntry().getValue()));
}
}
/**
* Puts an entry only if there is no entry with the key already present. If key already present then the existing
* value will be returned to the handler, otherwise null.
*
* @param k - holds the entry's key.
* @param v - holds the entry's value.
* @return future existing value if k is already present, otherwise future null.
*/
private Future putIfAbsent(K k, V v, Optional ttl) {
// set the Check-And-Set index. If the index is {@code 0}, Consul will only put the key if it does not already exist.
KeyValueOptions casOpts = new KeyValueOptions().setCasIndex(0);
return putValue(k, v, casOpts, ttl).compose(putSucceeded -> {
if (putSucceeded) return succeededFuture();
else return getValue(k); // key already present
});
}
/**
* Puts an entry by taking into account TTL.
*
* @param k - holds the entry's key.
* @param v - holds the entry's value.
* @param keyValueOptions - cas, this might be null.
* @param ttl - ttl on entry in ms.
* @return {@link Future} holding the result.
*/
private Future putValue(K k, V v, KeyValueOptions keyValueOptions, Optional ttl) {
Long ttlValue = ttl.map(aLong -> ttl.get()).orElse(null);
return asFutureString(k, v, appContext.getNodeId(), ttlValue)
.compose(value -> putPlainValue(keyPath(k), value, keyValueOptions))
.compose(result ->
ttlMonitor.apply(keyPath(k), ttl)
.compose(aVoid -> succeededFuture(result)));
}
/**
* Dedicated to {@link AsyncMap} TTL monitor to handle the ability to place ttl on map's entries.
*
* IMPORTANT:
* TTL can placed on consul entries by relaying on consul sessions (first we have to register ttl session and bind it with an entry) - once
* session gets expired (session's ttl gets expired) -> all entries given session was bound to get removed automatically from consul kv store.
* Consul's got following restriction :
* - Session TTL value must be between 10s and 86400s -> we can't really rely on using consul sessions since it breaks general
* vert.x cluster management SPI. This also should be taken into account:
* [Invalidation-time is twice the TTL time](https://github.com/hashicorp/consul/issues/1172) -> actual time when ttl entry gets removed (expired)
* is doubled to what you will specify as a ttl.
*
* For these reasons custom TTL monitoring mechanism was developed.
*
* @author Roman Levytskyi
*/
private static class TTLMonitor {
private final static Logger log = LoggerFactory.getLogger(TTLMonitor.class);
private final Vertx vertx;
private final ClusterManager clusterManager;
/*
* TTL monitor needs to hold a state - i.e. some sort of correlation between scheduled timers and
* corresponding keypaths on which ttl action is gonna get executed. We use vert.x {@link LocalMap}
* to hold this state. Having this allows us to either stop OR reschedule an appropriate timer.
*/
private final LocalMap timerMap;
private final String nodeId;
private final String mapName;
TTLMonitor(Vertx vertx, ClusterManager clusterManager, String mapName, String nodeId) {
this.vertx = vertx;
this.timerMap = vertx.sharedData().getLocalMap("timerMap");
this.clusterManager = clusterManager;
this.mapName = mapName;
this.nodeId = nodeId;
}
/**
* Monitors specified keypath on TTL.
* If ttl is not present then we attempt to cancel or reschedule the timer (if it was already scheduled on specified keypath.)
* If ttl is present we attempt to get a lock and schedule an appropriate vert.x scheduler.
*
* @param keyPath represents consul key path that will be monitored.
* @param ttl time to live in ms.
* @return
*/
Future apply(String keyPath, Optional ttl) {
Promise promise = Promise.promise();
if (ttl.isPresent()) {
if (log.isDebugEnabled()) {
log.debug("[" + nodeId + "] : " + "applying ttl monitoring on: " + keyPath + " with ttl: " + ttl.get());
}
String lockName = "ttlLockOn/" + keyPath;
clusterManager.getLockWithTimeout(lockName, 50, lockObtainedEvent -> {
setTimer(keyPath, ttl.get(), lockName, lockObtainedEvent);
promise.complete();
});
} else {
// there's no need to monitor an entry -> no ttl is there.
// try to remove keyPath from timerMap
cancelTimer(keyPath);
promise.complete();
}
return promise.future();
}
/**
* Schedules a timer for ttl action to take place.
*
* @param keyPath consul key path.
* @param ttl the delay in milliseconds, after which the timer will fire.
* @param lockName lock name that is being put to execute the ttl action.
* @param lockEvent lock event holding an actual lock.
*/
private void setTimer(String keyPath, long ttl, String lockName, AsyncResult lockEvent) {
long timerId = vertx.setTimer(ttl, event -> {
if (lockEvent.succeeded()) {
deleteTTLEntry(keyPath, lockEvent.result());
} else {
clusterManager.getLockWithTimeout(lockName, 1000, lockObtainedEvent -> {
if (lockObtainedEvent.succeeded()) {
deleteTTLEntry(keyPath, lockObtainedEvent.result());
}
});
}
});
timerMap.put(keyPath, timerId);
}
/**
* Cancels vert.x timer and updates timer map accordingly.
*/
private void cancelTimer(String keyPath) {
Long timerId = timerMap.get(keyPath);
if (Objects.nonNull(timerId)) {
vertx.cancelTimer(timerId);
timerMap.remove(keyPath);
if (log.isDebugEnabled()) {
log.debug("[" + nodeId + "] : " + "cancelling ttl monitoring on entry: " + keyPath);
}
}
}
/**
* Deletes an entry that ttl was bound to.
* We lock delete operation and once delete is executed:
* 1) we release the lock.
* 2) we update timer map by removing timer id that has triggered delete operation.
*
* @param keyPath entry's keypath in consul kv store.
* @param lock lock holding the delete operation.
*/
private void deleteTTLEntry(String keyPath, Lock lock) {
clusterManager.getAsyncMap(mapName, asyncMapEvent -> {
ConsulAsyncMap asyncMap = (ConsulAsyncMap) asyncMapEvent.result();
asyncMap.deleteValueByKeyPath(keyPath).setHandler(deleteResult -> {
lock.release();
timerMap.remove(keyPath);
});
});
}
}
}