This library provides the way to perform any computations wrapped with Mono with exclusive locking in the reactive manner.

In most cases you should avoid to use it. But if you have the requirement to minimize concurrent calls of some services with or without caching, reactor-lock may be useful.

Dependencies

<dependency>
  <groupId>com.github.alex-pumpkin</groupId>
  <artifactId>reactor-lock-core</artifactId>
  <version>0.2.0</version>
</dependency>

implementation 'com.github.alex-pumpkin:reactor-lock-core:0.2.0'

Exclusive subscription by key

public <K, V> Mono<V> callServiceByKeyWithLock(K key) {
    return LockMono.key(key)
            .lock(callServiceByKey(key));
}

private <K, V> Mono<V> callServiceByKey(K key) {
    return Mono.fromCallable(() -> {...});
}

Caching with exclusive subscription to the original Mono

public <K, V> Mono<V> callServiceByKeyWithCache(K key) {
    return LockCacheMono.create(LockMono.key(key).build())
            .lookup(k -> Mono.justOrEmpty(CACHE.get(k)).map(Signal::next))
            .onCacheMissResume(() -> callServiceByKey(key))
            .andWriteWith((k, signal) -> Mono.fromRunnable(() -> Optional.ofNullable(signal.get())
                    .ifPresent(v -> CACHE.put(k, v))));
}

private <K, V> Mono<V> callServiceByKey(K key) {
    return Mono.fromCallable(() -> {...});
}

Map<K, Signal<V>> MAP_CACHE = ...;

public <K, V> Mono<V> callServiceByKeyWithCache(K key) {
    return LockCacheMono.create(LockMono.key(key).build())
            .lookup(MAP_CACHE)
            .onCacheMissResume(() -> callServiceByKey(key));
}

private <K, V> Mono<V> callServiceByKey(K key) {
    return Mono.fromCallable(() -> {...});
}

Copyright 2019 Alexander Pankin

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

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.