Distributed collections

7.1. Map

Redis based distributed Map object for Java implements ConcurrentMap interface. Consider to use Live Object service to store POJO object as Redis Map.

It has Async, Reactive and RxJava2 interfaces.

If Map used mostly for read operations and/or network roundtrips are undesirable use Map with Local cache support.

RMap<String, SomeObject> map = redisson.getMap("anyMap");
SomeObject prevObject = map.put("123", new SomeObject());
SomeObject currentObject = map.putIfAbsent("323", new SomeObject());
SomeObject obj = map.remove("123");

// use fast* methods when previous value is not required
map.fastPut("a", new SomeObject());
map.fastPutIfAbsent("d", new SomeObject());
map.fastRemove("b");

RFuture<SomeObject> putAsyncFuture = map.putAsync("321");
RFuture<Void> fastPutAsyncFuture = map.fastPutAsync("321");

map.fastPutAsync("321", new SomeObject());
map.fastRemoveAsync("321");

RMap object allows to bind a Lock/ReadWriteLock/Semaphore/CountDownLatch object per key:

RMap<MyKey, MyValue> map = redisson.getMap("anyMap");
MyKey k = new MyKey();
RLock keyLock = map.getLock(k);
keyLock.lock();
try {
   MyValue v = map.get(k);
   // process value ...
} finally {
   keyLock.unlock();
}

RReadWriteLock rwLock = map.getReadWriteLock(k);
rwLock.readLock().lock();
try {
   MyValue v = map.get(k);
   // process value ...
} finally {
   keyLock.readLock().unlock();
}

7.1.1. Map eviction, local cache and data partitioning

Redisson provides various Map structure implementations with three important features:

local cache - so called near cache used to speed up read operations and avoid network roundtrips. It caches Map entries on Redisson side and executes read operations up to 45x faster in comparison with common implementation. Local cache instances with the same name connected to single pub/sub channel used for messaging between them, in particular to send entity update or entity invalidate event.

data partitioning - data partitioning in cluster mode. It allows to scale available memory, read/write operations and entry eviction process for individual Map instance in Redis cluster.

eviction - allows to define time to live or max idle time for each map entry.

Below is the list of all available Map implementations:

RedissonClient method name	Local cache	Data partitioning	Eviction
getMap()
getMapCache()
getLocalCachedMap()
getLocalCachedMapCache() available only in Redisson PRO edition
getClusteredMap() available only in Redisson PRO edition
getClusteredMapCache() available only in Redisson PRO edition
getClusteredLocalCachedMap() available only in Redisson PRO edition
getClusteredLocalCachedMapCache() available only in Redisson PRO edition

Redisson also provides Spring Cache and JCache implementations.

Eviction

Map object with eviction support implements org.redisson.api.RMapCache interface and extends java.util.concurrent.ConcurrentMap interface. It also has Async, Reactive and RxJava2 interfaces.

Current Redis implementation doesn't have map entry eviction functionality. Therefore expired entries are cleaned time to time by org.redisson.eviction.EvictionScheduler. It removes 100 expired entries at once. Task launch time tuned automatically and depends on expired entries amount deleted in previous time and varies between 5 second to half an hour. Thus if clean task deletes 100 entries each time it will be executed every 5 seconds (minimum execution delay). But if current expired entries amount is lower than previous one then execution delay will be increased by 1.5 times and decreased otherwise.

It's recommended to use single instance of RMapCache object with the same name and bounded to the same Redisson client.

Code example:

RMapCache<String, SomeObject> map = redisson.getMapCache("anyMap");
// or
RMapCache<String, SomeObject> map = redisson.getLocalCachedMapCache("anyMap", LocalCachedMapOptions.defaults());
// or
RMapCache<String, SomeObject> map = redisson.getClusteredLocalCachedMapCache("anyMap", LocalCachedMapOptions.defaults());
// or
RMapCache<String, SomeObject> map = redisson.getClusteredMapCache("anyMap");


// ttl = 10 minutes, 
map.put("key1", new SomeObject(), 10, TimeUnit.MINUTES);
// ttl = 10 minutes, maxIdleTime = 10 seconds
map.put("key1", new SomeObject(), 10, TimeUnit.MINUTES, 10, TimeUnit.SECONDS);

// ttl = 3 seconds
map.putIfAbsent("key2", new SomeObject(), 3, TimeUnit.SECONDS);
// ttl = 40 seconds, maxIdleTime = 10 seconds
map.putIfAbsent("key2", new SomeObject(), 40, TimeUnit.SECONDS, 10, TimeUnit.SECONDS);

// if object is not used anymore
map.destroy();

Local cache

Map object with local cache support implements org.redisson.api.RLocalCachedMap which extends ConcurrentMap interface. It's recommended to use single instance of LocalCachedMap instance per name and JVM instance. Same LocalCachedMapOptions should be used across all instances with the same name.

Follow options could be supplied during object creation:

LocalCachedMapOptions options = LocalCachedMapOptions.defaults()

// Defines store mode of cache data.
// Follow options are available:
// LOCALCACHE - store data in local cache only.
// LOCALCACHE_REDIS - store data in both Redis and local cache.
.storeMode(StoreMode.LOCALCACHE_REDIS)

// Defines Cache provider used as local cache store.
// Follow options are available:
// REDISSON - uses Redisson own implementation
// CAFFEINE - uses Caffeine implementation
.cacheProvider(CacheProvider.REDISSON)

// Defines local cache eviction policy.
// Follow options are available:
// LFU - Counts how often an item was requested. Those that are used least often are discarded first.
// LRU - Discards the least recently used items first
// SOFT - Uses weak references, entries are removed by GC
// WEAK - Uses soft references, entries are removed by GC
// NONE - No eviction
.evictionPolicy(EvictionPolicy.NONE)

// If cache size is 0 then local cache is unbounded.
.cacheSize(1000)

// Used to load missed updates during any connection failures to Redis.
// Since, local cache updates can't be get in absence of connection to Redis.
// Follow reconnection strategies are available:
// CLEAR - Clear local cache if map instance has been disconnected for a while.
// LOAD - Store invalidated entry hash in invalidation log for 10 minutes
// Cache keys for stored invalidated entry hashes will be removed
// if LocalCachedMap instance has been disconnected less than 10 minutes
// or whole cache will be cleaned otherwise.
// NONE - Default. No reconnection handling
.reconnectionStrategy(ReconnectionStrategy.NONE)

// Used to synchronize local cache changes.
// Follow sync strategies are available:
// INVALIDATE - Default. Invalidate cache entry across all LocalCachedMap instances on map entry change
// UPDATE - Update cache entry across all LocalCachedMap instances on map entry change
// NONE - No synchronizations on map changes
.syncStrategy(SyncStrategy.INVALIDATE)

// time to live for each map entry in local cache
.timeToLive(10000)
// or
.timeToLive(10, TimeUnit.SECONDS)

// max idle time for each map entry in local cache
.maxIdle(10000)
// or
.maxIdle(10, TimeUnit.SECONDS);

Code example:

RLocalCachedMap<String, Integer> map = redisson.getLocalCachedMap("test", LocalCachedMapOptions.defaults());
// or
RLocalCachedMap<String, SomeObject> map = redisson.getLocalCachedMapCache("anyMap", LocalCachedMapOptions.defaults());
// or
RLocalCachedMap<String, SomeObject> map = redisson.getClusteredLocalCachedMapCache("anyMap", LocalCachedMapOptions.defaults());
// or
RLocalCachedMap<String, SomeObject> map = redisson.getClusteredLocalCachedMap("anyMap", LocalCachedMapOptions.defaults());

        
String prevObject = map.put("123", 1);
String currentObject = map.putIfAbsent("323", 2);
String obj = map.remove("123");

// use fast* methods when previous value is not required
map.fastPut("a", 1);
map.fastPutIfAbsent("d", 32);
map.fastRemove("b");

RFuture<String> putAsyncFuture = map.putAsync("321");
RFuture<Void> fastPutAsyncFuture = map.fastPutAsync("321");

map.fastPutAsync("321", new SomeObject());
map.fastRemoveAsync("321");

Object should be destroyed if it not used anymore, but it's not necessary to call destroy method if Redisson goes shutdown.

RLocalCachedMap<String, Integer> map = ...
map.destroy();

How to load data to avoid invalidation messages traffic.

Code example:

    public void loadData(String cacheName, Map<String, String> data) {
        RLocalCachedMap<String, String> clearMap = redisson.getLocalCachedMap(cacheName, 
                LocalCachedMapOptions.defaults().cacheSize(1).syncStrategy(SyncStrategy.INVALIDATE));
        RLocalCachedMap<String, String> loadMap = redisson.getLocalCachedMap(cacheName, 
                LocalCachedMapOptions.defaults().cacheSize(1).syncStrategy(SyncStrategy.NONE));
        
        loadMap.putAll(data);
        clearMap.clearLocalCache();
    }

Data partitioning

Map object with data partitioning support implements org.redisson.api.RClusteredMap which extends java.util.concurrent.ConcurrentMap interface. Read more details about data partitioning here.

Code example:

RClusteredMap<String, SomeObject> map = redisson.getClusteredMap("anyMap");
// or
RClusteredMap<String, SomeObject> map = redisson.getClusteredLocalCachedMapCache("anyMap", LocalCachedMapOptions.defaults());
// or
RClusteredMap<String, SomeObject> map = redisson.getClusteredLocalCachedMap("anyMap", LocalCachedMapOptions.defaults());
// or
RClusteredMap<String, SomeObject> map = redisson.getClusteredMapCache("anyMap");

SomeObject prevObject = map.put("123", new SomeObject());
SomeObject currentObject = map.putIfAbsent("323", new SomeObject());
SomeObject obj = map.remove("123");

map.fastPut("321", new SomeObject());
map.fastRemove("321");

7.1.2. Map persistence

Redisson allows to store Map data in external storage along with Redis store. Use cases:

Redisson Map object as a cache between an application and external storage.
Increase durability of Redisson Map data and life-span of evicted entries.
Caching for databases, web services or any other data source.

Read-through strategy

If requested entry doesn't exist in the Redisson Map object when it will be loaded using provided MapLoader object. Code example:

        MapLoader<String, String> mapLoader = new MapLoader<String, String>() {
            
            @Override
            public Iterable<String> loadAllKeys() {
                List<String> list = new ArrayList<String>();
                Statement statement = conn.createStatement();
                try {
                    ResultSet result = statement.executeQuery("SELECT id FROM student");
                    while (result.next()) {
                        list.add(result.getString(1));
                    }
                } finally {
                    statement.close();
                }

                return list;
            }
            
            @Override
            public String load(String key) {
                PreparedStatement preparedStatement = conn.prepareStatement("SELECT name FROM student where id = ?");
                try {
                    preparedStatement.setString(1, key);
                    ResultSet result = preparedStatement.executeQuery();
                    if (result.next()) {
                        return result.getString(1);
                    }
                    return null;
                } finally {
                    preparedStatement.close();
                }
            }
        };

Configuration example:

MapOptions<K, V> options = MapOptions.<K, V>defaults()
                              .loader(mapLoader);

RMap<K, V> map = redisson.getMap("test", options);
// or
RMapCache<K, V> map = redisson.getMapCache("test", options);
// or with boost up to 45x times 
RLocalCachedMap<K, V> map = redisson.getLocalCachedMap("test", options);
// or with boost up to 45x times 
RLocalCachedMapCache<K, V> map = redisson.getLocalCachedMapCache("test", options);

Write-through (synchronous) strategy

When the Map entry is being updated method won't return until Redisson update it in an external storage using MapWriter object. Code example:

        MapWriter<String, String> mapWriter = new MapWriter<String, String>() {
            
            @Override
            public void write(Map<String, String> map) {
                PreparedStatement preparedStatement = conn.prepareStatement("INSERT INTO student (id, name) values (?, ?)");
                try {
                    for (Entry<String, String> entry : map.entrySet()) {
                        preparedStatement.setString(1, entry.getKey());
                        preparedStatement.setString(2, entry.getValue());
                        preparedStatement.addBatch();
                    }
                    preparedStatement.executeBatch();
                } finally {
                    preparedStatement.close();
                }
            }
            
            @Override
            public void delete(Collection<String> keys) {
                PreparedStatement preparedStatement = conn.prepareStatement("DELETE FROM student where id = ?");
                try {
                    for (String key : keys) {
                        preparedStatement.setString(1, key);
                        preparedStatement.addBatch();
                    }
                    preparedStatement.executeBatch();
                } finally {
                    preparedStatement.close();
                }
            }
        };

Configuration example:

MapOptions<K, V> options = MapOptions.<K, V>defaults()
                              .writer(mapWriter)
                              .writeMode(WriteMode.WRITE_THROUGH);

RMap<K, V> map = redisson.getMap("test", options);
// or
RMapCache<K, V> map = redisson.getMapCache("test", options);
// or with boost up to 45x times 
RLocalCachedMap<K, V> map = redisson.getLocalCachedMap("test", options);
// or with boost up to 45x times 
RLocalCachedMapCache<K, V> map = redisson.getLocalCachedMapCache("test", options);

Write-behind (asynchronous) strategy

Updates of Map object are accumulated in batches and asynchronously written with defined delay to external storage through MapWriter object.
writeBehindDelay - delay of batched write or delete operation. Default value is 1000 milliseconds.writeBehindBatchSize - size of batch. Each batch contains Map Entry write or delete commands. Default value is 50.

Configuration example:

MapOptions<K, V> options = MapOptions.<K, V>defaults()
                              .writer(mapWriter)
                              .writeMode(WriteMode.WRITE_BEHIND)
                              .writeBehindDelay(5000)
                              .writeBehindBatchSize(100);

RMap<K, V> map = redisson.getMap("test", options);
// or
RMapCache<K, V> map = redisson.getMapCache("test", options);
// or with boost up to 45x times 
RLocalCachedMap<K, V> map = redisson.getLocalCachedMap("test", options);
// or with boost up to 45x times 
RLocalCachedMapCache<K, V> map = redisson.getLocalCachedMapCache("test", options);

This feature available for RMap, RMapCache, RLocalCachedMap and RLocalCachedMapCache objects.

Usage of RLocalCachedMap and RLocalCachedMapCache objects boost Redis read-operations up to 45x times and give almost instant speed for database, web service or any other data source.

7.1.3. Map listeners

Redisson allows to bind listeners for Map object which implements RMapCache interface and track follow events over Map data:

Entry created - org.redisson.api.map.event.EntryCreatedListener
Entry expired - org.redisson.api.map.event.EntryExpiredListener
Entry removed - org.redisson.api.map.event.EntryRemovedListener
Entry updated - org.redisson.api.map.event.EntryUpdatedListener

Usage examples:

RMapCache<String, SomeObject> map = redisson.getMapCache("anyMap");
// or
RMapCache<String, SomeObject> map = redisson.getLocalCachedMapCache("anyMap", LocalCachedMapOptions.defaults());
// or
RMapCache<String, SomeObject> map = redisson.getClusteredLocalCachedMapCache("anyMap", LocalCachedMapOptions.defaults());
// or
RMapCache<String, SomeObject> map = redisson.getClusteredMapCache("anyMap");


int updateListener = map.addListener(new EntryUpdatedListener<Integer, Integer>() {
     @Override
     public void onUpdated(EntryEvent<Integer, Integer> event) {
          event.getKey(); // key
          event.getValue() // new value
          event.getOldValue() // old value
          // ...
     }
});

int createListener = map.addListener(new EntryCreatedListener<Integer, Integer>() {
     @Override
     public void onCreated(EntryEvent<Integer, Integer> event) {
          event.getKey(); // key
          event.getValue() // value
          // ...
     }
});

int expireListener = map.addListener(new EntryExpiredListener<Integer, Integer>() {
     @Override
     public void onExpired(EntryEvent<Integer, Integer> event) {
          event.getKey(); // key
          event.getValue() // value
          // ...
     }
});

int removeListener = map.addListener(new EntryRemovedListener<Integer, Integer>() {
     @Override
     public void onRemoved(EntryEvent<Integer, Integer> event) {
          event.getKey(); // key
          event.getValue() // value
          // ...
     }
});

map.removeListener(updateListener);
map.removeListener(createListener);
map.removeListener(expireListener);
map.removeListener(removeListener);

7.1.4. LRU bounded Map

Map object which implements RMapCache interface could be LRU bounded. LRU bounded Map allows to store map entries within defined limit and retire entries in Least Recently Used (LRU) order.

RMapCache<String, SomeObject> map = redisson.getMapCache("anyMap");
// or
RMapCache<String, SomeObject> map = redisson.getLocalCachedMapCache("anyMap", LocalCachedMapOptions.defaults());
// or
RMapCache<String, SomeObject> map = redisson.getClusteredLocalCachedMapCache("anyMap", LocalCachedMapOptions.defaults());
// or
RMapCache<String, SomeObject> map = redisson.getClusteredMapCache("anyMap");


// tries to set limit map to 10 entries
map.trySetMaxSize(10);

// set or change limit map to 10 entries
map.setMaxSize(10);

map.put("1", "2");
map.put("3", "3", 1, TimeUnit.SECONDS);

7.2. Multimap

Redis based Multimap for Java allows to bind multiple values per key. Keys amount limited by Redis to 4 294 967 295 elements.

It has Async, Reactive and RxJava2 interfaces.

7.2.1. Set based Multimap

Set based Multimap doesn't allow duplications for values per key.

RSetMultimap<SimpleKey, SimpleValue> map = redisson.getSetMultimap("myMultimap");
map.put(new SimpleKey("0"), new SimpleValue("1"));
map.put(new SimpleKey("0"), new SimpleValue("2"));
map.put(new SimpleKey("3"), new SimpleValue("4"));

Set<SimpleValue> allValues = map.get(new SimpleKey("0"));

List<SimpleValue> newValues = Arrays.asList(new SimpleValue("7"), new SimpleValue("6"), new SimpleValue("5"));
Set<SimpleValue> oldValues = map.replaceValues(new SimpleKey("0"), newValues);

Set<SimpleValue> removedValues = map.removeAll(new SimpleKey("0"));

7.2.2. List based Multimap

List based Multimap object for Java stores entries in insertion order and allows duplicates for values mapped to key.

RListMultimap<SimpleKey, SimpleValue> map = redisson.getListMultimap("test1");
map.put(new SimpleKey("0"), new SimpleValue("1"));
map.put(new SimpleKey("0"), new SimpleValue("2"));
map.put(new SimpleKey("0"), new SimpleValue("1"));
map.put(new SimpleKey("3"), new SimpleValue("4"));

List<SimpleValue> allValues = map.get(new SimpleKey("0"));

Collection<SimpleValue> newValues = Arrays.asList(new SimpleValue("7"), new SimpleValue("6"), new SimpleValue("5"));
List<SimpleValue> oldValues = map.replaceValues(new SimpleKey("0"), newValues);

List<SimpleValue> removedValues = map.removeAll(new SimpleKey("0"));

7.2.3. Multimap eviction

Multimap object for Java with eviction support implemented by separated MultimapCache object. There are RSetMultimapCache and RListMultimapCache objects for Set and List Multimaps respectivly.

Expired entries are cleaned by org.redisson.EvictionScheduler. It removes 100 expired entries at once. Task launch time tuned automatically and depends on expired entries amount deleted in previous time and varies between 1 second to 2 hours. Thus if clean task deletes 100 entries each time it will be executed every second (minimum execution delay). But if current expired entries amount is lower than previous one then execution delay will be increased by 1.5 times.

RSetMultimapCache example:

RSetMultimapCache<String, String> multimap = redisson.getSetMultimapCache("myMultimap");
multimap.put("1", "a");
multimap.put("1", "b");
multimap.put("1", "c");

multimap.put("2", "e");
multimap.put("2", "f");

multimap.expireKey("2", 10, TimeUnit.MINUTES);

7.3. Set

Redis based Set object for Java implements java.util.Set interface. Keeps elements uniqueness via element state comparison. Set size limited by Redis to 4 294 967 295 elements.

It has Async, Reactive and RxJava2 interfaces.

RSet<SomeObject> set = redisson.getSet("anySet");
set.add(new SomeObject());
set.remove(new SomeObject());

RSet object allows to bind a Lock/ReadWriteLock/Semaphore/CountDownLatch object per value:

RSet<MyObject> set = redisson.getSet("anySet");
MyObject value = new MyObject();
RLock lock = map.getLock(value);
lock.lock();
try {
   // process value ...
} finally {
   lock.unlock();
}

7.3.1. Set eviction and data partitioning

Redisson provides various Set structure implementations with two important features:

data partitioning - data partitioning in cluster mode. It allows to scale available memory, read/write operations and entry eviction process for individual Set instance in Redis cluster.

eviction - allows to define time to live per set value.

Below is the list of all available Map implementations:

RedissonClient method name	Data partitioning support	Eviction support
getSet()	No	No
getSetCache()	No	Yes
getClusteredSet() available only in Redisson PRO edition	Yes	No
getClusteredSetCache() available only in Redisson PRO edition	Yes	Yes

Eviction

Map object with eviction support implements org.redisson.api.RSetCache which extends java.util.Set interface. It has Async, Reactive and RxJava2 interfaces.

Current Redis implementation doesn't have set value eviction functionality. Therefore expired entries are cleaned by org.redisson.eviction.EvictionScheduler. It removes 300 expired entries at once. Task launch time tuned automatically and depends on expired entries amount deleted in previous time and varies between 1 second to 1 hour. Thus if clean task deletes 300 entries each time it will be executed every second (minimum execution delay). But if current expired values amount is lower than previous one then execution delay will be increased by 1.5 times.

Code example:

RSetCache<SomeObject> set = redisson.getSetCache("mySet");
// or
RMapCache<SomeObject> set = redisson.getClusteredSetCache("mySet");

// ttl = 10 minutes, 
set.add(new SomeObject(), 10, TimeUnit.MINUTES);

// if object is not used anymore
map.destroy();

Data partitioning

Map object with data partitioning support implements org.redisson.api.RClusteredSet which extends java.util.Set interface. Read more details about data partitioning here.

Code example:

RClusteredSet<SomeObject> set = redisson.getClusteredSet("mySet");
// or
RClusteredSet<SomeObject> set = redisson.getClusteredSetCache("mySet");

// ttl = 10 minutes, 
map.add(new SomeObject(), 10, TimeUnit.MINUTES);

7.4. SortedSet

Redis based distributed SortedSet for Java implements java.util.SortedSet interface. It uses comparator to sort elements and keep uniqueness. For String data type it's recommended to use LexSortedSet object due to performance gain.

RSortedSet<Integer> set = redisson.getSortedSet("anySet");
set.trySetComparator(new MyComparator()); // set object comparator
set.add(3);
set.add(1);
set.add(2);

set.removeAsync(0);
set.addAsync(5);

7.5. ScoredSortedSet

Redis based distributed ScoredSortedSet object. Sorts elements by score defined during element insertion. Keeps elements uniqueness via element state comparison.

It has Async, Reactive and RxJava2 interfaces. Set size is limited by Redis to 4 294 967 295 elements.

RScoredSortedSet<SomeObject> set = redisson.getScoredSortedSet("simple");

set.add(0.13, new SomeObject(a, b));
set.addAsync(0.251, new SomeObject(c, d));
set.add(0.302, new SomeObject(g, d));

set.pollFirst();
set.pollLast();

int index = set.rank(new SomeObject(g, d)); // get element index
Double score = set.getScore(new SomeObject(g, d)); // get element score

7.6. LexSortedSet

Redis based distributed Set object for Java allows String objects only and implements java.util.Set<String> interface. It keeps elements in lexicographical order and maintain elements uniqueness via element state comparison.

It has Async, Reactive and RxJava2 interfaces.

RLexSortedSet set = redisson.getLexSortedSet("simple");
set.add("d");
set.addAsync("e");
set.add("f");

set.lexRangeTail("d", false);
set.lexCountHead("e");
set.lexRange("d", true, "z", false);

7.7. List

Redis based distributed List object for Java implements java.util.List interface. It keeps elements in insertion order.

It has Async, Reactive and RxJava2 interfaces. List size is limited by Redis to 4 294 967 295 elements.

RList<SomeObject> list = redisson.getList("anyList");
list.add(new SomeObject());
list.get(0);
list.remove(new SomeObject());

7.8. Queue

Redis based distributed unbounded Queue object for Java implements java.util.Queue interface.

It has Async, Reactive and RxJava2 interfaces.

RQueue<SomeObject> queue = redisson.getQueue("anyQueue");
queue.add(new SomeObject());
SomeObject obj = queue.peek();
SomeObject someObj = queue.poll();

7.9. Deque

Redis based distributed unbounded Deque object for Java implements java.util.Deque interface.

It has Async, Reactive and RxJava2 interfaces.

RDeque<SomeObject> queue = redisson.getDeque("anyDeque");
queue.addFirst(new SomeObject());
queue.addLast(new SomeObject());
SomeObject obj = queue.removeFirst();
SomeObject someObj = queue.removeLast();

7.10. Blocking Queue

Redis based distributed unbounded BlockingQueue object for Java implements java.util.concurrent.BlockingQueue interface.

It has Async, Reactive and RxJava2 interfaces.

RBlockingQueue<SomeObject> queue = redisson.getBlockingQueue("anyQueue");

queue.offer(new SomeObject());

SomeObject obj = queue.peek();
SomeObject obj = queue.poll();
SomeObject obj = queue.poll(10, TimeUnit.MINUTES);

poll, pollFromAny, pollLastAndOfferFirstTo and take methods are resubscribed automatically during re-connection to Redis server or failover.

7.11. Bounded Blocking Queue

Redis based distributed BoundedBlockingQueue for Java implements java.util.concurrent.BlockingQueue interface. BoundedBlockingQueue size limited by Redis to 4 294 967 295 elements.

Queue capacity should be defined once by trySetCapacity() method before the usage:

RBoundedBlockingQueue<SomeObject> queue = redisson.getBoundedBlockingQueue("anyQueue");
// returns `true` if capacity set successfully and `false` if it already set.
queue.trySetCapacity(2);

queue.offer(new SomeObject(1));
queue.offer(new SomeObject(2));
// will be blocked until free space available in queue
queue.put(new SomeObject());

SomeObject obj = queue.peek();
SomeObject someObj = queue.poll();
SomeObject ob = queue.poll(10, TimeUnit.MINUTES);

poll, pollFromAny, pollLastAndOfferFirstTo and take methods will be resubscribed automatically during reconnection to Redis server or Redis server failover.

7.12. Blocking Deque

Java implementation of Redis based BlockingDeque implements java.util.concurrent.BlockingDequeinterface.

It has Async, Reactive and RxJava2 interfaces.

RBlockingDeque<Integer> deque = redisson.getBlockingDeque("anyDeque");
deque.putFirst(1);
deque.putLast(2);
Integer firstValue = queue.takeFirst();
Integer lastValue = queue.takeLast();
Integer firstValue = queue.pollFirst(10, TimeUnit.MINUTES);
Integer lastValue = queue.pollLast(3, TimeUnit.MINUTES);

poll, pollFromAny, pollLastAndOfferFirstTo and take methods are resubscribed automatically during re-connection to Redis server or failover.

7.13. Blocking Fair Queue

Redis based distributed BlockingFairQueue for Java implements java.util.concurrent.BlockingQueueinterface.

When queue consumers in different parts of network: some of them closer to redis and some further. "further" consumers will get lower amount of messages from queue due to network delays. In turn "closer" consumers will get higher amount and this could lead to client overloading.

Blocking queue with fair polling guarantees access order for poll and take methods and allows to get uniformly distributed consumption.

RBlockingFairQueue queue = redisson.getBlockingFairQueue("myQueue");
queue.offer(new SomeObject());

SomeObject element = queue.peek();
SomeObject element = queue.poll();
SomeObject element = queue.poll(10, TimeUnit.MINUTES);
SomeObject element = queue.take();

This feature available only in Redisson PRO edition.

7.14. Blocking Fair Deque

Redis based distributed BlockingFairDeque for Java implements java.util.concurrent.BlockingDequeinterface.

When deque consumers in different parts of network: some of them closer to redis and some further. "further" consumers will get lower amount of messages from queue due to network delays. In turn "closer" consumers will get higher amount and this could lead to client overloading.

Blocking deque with fair polling guarantees access order for poll, take, pollFirst, takeFirst, pollLast and takeLast methods and allows to get uniformly distributed consumption.

RBlockingFairDeque deque = redisson.getBlockingFairDeque("myDeque");
deque.offer(new SomeObject());

SomeObject firstElement = queue.peekFirst();
SomeObject firstElement = queue.pollFirst();
SomeObject firstElement = queue.pollFirst(10, TimeUnit.MINUTES);
SomeObject firstElement = queue.takeFirst();

SomeObject lastElement = queue.peekLast();
SomeObject lastElement = queue.pollLast();
SomeObject lastElement = queue.pollLast(10, TimeUnit.MINUTES);
SomeObject lastElement = queue.takeLast();

This feature available only in Redisson PRO edition.

7.15. Delayed Queue

Redis based DelayedQueue object for Java allows to transfer each element to destination queue with specified delay. Could be useful for exponential backoff strategy used for message delivery to consumer. Destination queue could be any queue implemented RQueue interface.

RBlockingQueue<String> distinationQueue = ...
RDelayedQueue<String> delayedQueue = getDelayedQueue(distinationQueue);
// move object to distinationQueue in 10 seconds
delayedQueue.offer("msg1", 10, TimeUnit.SECONDS);
// move object to distinationQueue in 1 minutes
delayedQueue.offer("msg2", 1, TimeUnit.MINUTES);


// msg1 will appear in 10 seconds
distinationQueue.poll(15, TimeUnit.SECONDS);

// msg2 will appear in 2 seconds
distinationQueue.poll(2, TimeUnit.SECONDS);

Object should be destroyed if it not used anymore, but it's not necessary to call destroy method if Redisson goes shutdown.

RDelayedQueue<String> delayedQueue = ...
delayedQueue.destroy();

7.16. Priority Queue

Java implementation of Redis based PriorityQueue implements Queue interface. Elements are ordered according to natural order of Comparable interface or defined Comparator.

Use trySetComparator() method to define own Comparator.

Code example:

public class Entry implements Comparable<Entry>, Serializable {

    private String key;
    private Integer value;

    public Entry(String key, Integer value) {
        this.key = key;
        this.value = value;
    }

    @Override
    public int compareTo(Entry o) {
        return key.compareTo(o.key);
    }

}

RPriorityQueue<Entry> queue = redisson.getPriorityQueue("anyQueue");
queue.add(new Entry("b", 1));
queue.add(new Entry("c", 1));
queue.add(new Entry("a", 1));

// Entry [a:1]
Entry e = queue.poll();
// Entry [b:1]
Entry e = queue.poll();
// Entry [c:1]
Entry e = queue.poll();

7.17. Priority Deque

Java implementation of Redis based PriorityDeque implements Deque interface. Elements are ordered according to natural order of Comparable interface or defined Comparator.

Use trySetComparator() method to define own Comparator.

Code example:

public class Entry implements Comparable<Entry>, Serializable {

    private String key;
    private Integer value;

    public Entry(String key, Integer value) {
        this.key = key;
        this.value = value;
    }

    @Override
    public int compareTo(Entry o) {
        return key.compareTo(o.key);
    }

}

RPriorityDeque<Entry> queue = redisson.getPriorityDeque("anyQueue");
queue.add(new Entry("b", 1));
queue.add(new Entry("c", 1));
queue.add(new Entry("a", 1));

// Entry [a:1]
Entry e = queue.pollFirst();
// Entry [c:1]
Entry e = queue.pollLast();

7.18. Priority Blocking Queue

Java implementation of Redis based PriorityBlockingQueue similar to JDK PriorityBlockingQueueobject. Elements are ordered according to natural order of Comparable interface or defined Comparator.

Use trySetComparator() method to define own Comparator.

poll, pollLastAndOfferFirstTo and take methods are resubscribed automatically during re-connection to Redis server or failover.

Code example:

public class Entry implements Comparable<Entry>, Serializable {

    private String key;
    private Integer value;

    public Entry(String key, Integer value) {
        this.key = key;
        this.value = value;
    }

    @Override
    public int compareTo(Entry o) {
        return key.compareTo(o.key);
    }

}

RPriorityBlockingQueue<Entry> queue = redisson.getPriorityBlockingQueue("anyQueue");
queue.add(new Entry("b", 1));
queue.add(new Entry("c", 1));
queue.add(new Entry("a", 1));

// Entry [a:1]
Entry e = queue.take();

7.19. Priority Blocking Deque

Java implementation of Redis based PriorityBlockingDeque implements BlockingDeque interface. Elements are ordered according to natural order of Comparable interface or defined Comparator.

Use trySetComparator() method to define own Comparator.

poll, pollLastAndOfferFirstTo, take methods are resubscribed automatically during re-connection to Redis server or failover.

Code example:

public class Entry implements Comparable<Entry>, Serializable {

    private String key;
    private Integer value;

    public Entry(String key, Integer value) {
        this.key = key;
        this.value = value;
    }

    @Override
    public int compareTo(Entry o) {
        return key.compareTo(o.key);
    }

}

RPriorityBlockingDeque<Entry> queue = redisson.getPriorityBlockingDeque("anyQueue");
queue.add(new Entry("b", 1));
queue.add(new Entry("c", 1));
queue.add(new Entry("a", 1));

// Entry [a:1]
Entry e = queue.takeFirst();
// Entry [c:1]
Entry e = queue.takeLast();

7.20. Stream

Java implementation of Redis based Stream object wraps Redis Stream feature. Basically it allows to create Consumers Group which consume data added by Producers.

RStream<String, String> stream = redisson.getStream("test");

StreamMessageId sm = stream.add("0", "0");

stream.createGroup("testGroup");
        
StreamId id1 = stream.add("1", "1");
StreamId id2 = stream.add("2", "2");
        
Map<StreamId, Map<String, String>> group = stream.readGroup("testGroup", "consumer1");
long amount = stream.ack("testGroup", id1, id2));

Code example of Async interface usage:

RStream<String, String> stream = redisson.getStream("test");

RFuture<StreamMessageId> smFuture = stream.addAsync("0", "0");

RFuture<Void> groupFuture = stream.createGroupAsync("testGroup");
        
RFuture<StreamId> id1Future = stream.addAsync("1", "1");
RFuture<StreamId> id2Future = stream.addAsync("2", "2");
        
RFuture<Map<StreamId, Map<String, String>>> groupResultFuture = stream.readGroupAsync("testGroup", "consumer1");
RFuture<Long> amountFuture = stream.ackAsync("testGroup", id1, id2));

amountFuture.whenComplete((res, exception) -> {
    // ...
});

Code example of Reactive interface usage:

RedissonReactiveClient redisson = Redisson.createReactive(config);
RStreamReactive<String, String> stream = redisson.getStream("test");

Mono<StreamMessageId> smMono = stream.add("0", "0");

Mono<Void> groupMono = stream.createGroup("testGroup");
        
Mono<StreamId> id1Mono = stream.add("1", "1");
Mono<StreamId> id2Mono = stream.add("2", "2");
        
Mono<Map<StreamId, Map<String, String>>> groupMono = stream.readGroup("testGroup", "consumer1");
Mono<Long> amountMono = stream.ack("testGroup", id1, id2));

amountMono.doOnNext(res -> {
   // ...
}).subscribe();

Code example of RxJava2 interface usage:

RedissonRxClient redisson = Redisson.createRx(config);
RStreamRx<String, String> stream = redisson.getStream("test");

Single<StreamMessageId> smRx = stream.add("0", "0");

Completable groupRx = stream.createGroup("testGroup");
        
Single<StreamId> id1Rx = stream.add("1", "1");
Single<StreamId> id2Rx = stream.add("2", "2");
        
Single<Map<StreamId, Map<String, String>>> groupRx = stream.readGroup("testGroup", "consumer1");
Single<Long> amountRx = stream.ack("testGroup", id1, id2));

amountRx.doOnSuccess(res -> {
   // ...
}).subscribe();

7.21. Ring Buffer

Java implementation of Redis based RingBuffer implements java.util.Queue interface. This structure evicts elements from the head if queue capacity became full.

Should be initialized with capacity size by trySetCapacity() method before usage.

Code example:

RRingBuffer<Integer> buffer = redisson.getRingBuffer("test");

// buffer capacity is 4 elements
buffer.trySetCapacity(4);

buffer.add(1);
buffer.add(2);
buffer.add(3);
buffer.add(4);

// buffer state is 1, 2, 3, 4

buffer.add(5);
buffer.add(6);

// buffer state is 3, 4, 5, 6

Code example of Async interface usage:

RRingBuffer<Integer> buffer = redisson.getRingBuffer("test");

// buffer capacity is 4 elements
RFuture<Boolean> capacityFuture = buffer.trySetCapacityAsync(4);

RFuture<Boolean> addFuture = buffer.addAsync(1);
RFuture<Boolean> addFuture = buffer.addAsync(2);
RFuture<Boolean> addFuture = buffer.addAsync(3);
RFuture<Boolean> addFuture = buffer.addAsync(4);

// buffer state is 1, 2, 3, 4

RFuture<Boolean> addFuture = buffer.addAsync(5);
RFuture<Boolean> addFuture = buffer.addAsync(6);

// buffer state is 3, 4, 5, 6

addFuture.whenComplete((res, exception) -> {
    // ...
});

Code example of Reactive interface usage:

RedissonReactiveClient redisson = Redisson.createReactive(config);
RRingBufferReactive<Integer> buffer = redisson.getRingBuffer("test");

// buffer capacity is 4 elements
Mono<Boolean> capacityMono = buffer.trySetCapacity(4);

Mono<Boolean> addMono = buffer.add(1);
Mono<Boolean> addMono = buffer.add(2);
Mono<Boolean> addMono = buffer.add(3);
Mono<Boolean> addMono = buffer.add(4);

// buffer state is 1, 2, 3, 4

Mono<Boolean> addMono = buffer.add(5);
Mono<Boolean> addMono = buffer.add(6);

// buffer state is 3, 4, 5, 6

addMono.doOnNext(res -> {
   // ...
}).subscribe();

Code example of RxJava2 interface usage:

RedissonRxClient redisson = Redisson.createRx(config);
RRingBufferRx<Integer> buffer = redisson.getRingBuffer("test");

// buffer capacity is 4 elements
Single<Boolean> capacityRx = buffer.trySetCapacity(4);

Single<Boolean> addRx = buffer.add(1);
Single<Boolean> addRx = buffer.add(2);
Single<Boolean> addRx = buffer.add(3);
Single<Boolean> addRx = buffer.add(4);

// buffer state is 1, 2, 3, 4

Single<Boolean> addRx = buffer.add(5);
Single<Boolean> addRx = buffer.add(6);

// buffer state is 3, 4, 5, 6

addRx.doOnSuccess(res -> {
   // ...
}).subscribe();

7.22. Transfer Queue

Java implementation of Redis based TransferQueue implements set of transfer methods which return only when value was successfully hand off to consumer.

poll and take methods are resubscribed automatically during re-connection to Redis server or failover.

Code example:

RTransferQueue<String> queue = redisson.getTransferQueue("myCountDownLatch");

queue.transfer("data");
// or try transfer immediately
queue.tryTransfer("data");
// or try transfer up to 10 seconds
queue.tryTransfer("data", 10, TimeUnit.SECONDS);

// in other thread or JVM

queue.take();
// or
queue.poll();

Code example of Async interface usage:

RTransferQueue<String> queue = redisson.getTransferQueue("myCountDownLatch");

RFuture<Void> future = queue.transferAsync("data");
// or try transfer immediately
RFuture<Boolean> future = queue.tryTransferAsync("data");
// or try transfer up to 10 seconds
RFuture<Boolean> future = queue.tryTransferAsync("data", 10, TimeUnit.SECONDS);

// in other thread or JVM

RFuture<String> future = queue.takeAsync();
// or
RFuture<String> future = queue.pollAsync();

future.whenComplete((res, exception) -> {
    // ...
});

Code example of Reactive interface usage:

RedissonReactiveClient redisson = Redisson.createReactive(config);
RTransferQueueReactive<String> queue = redisson.getTransferQueue("myCountDownLatch");

Mono<Void> mono = queue.transfer("data");
// or try transfer immediately
Mono<Boolean> mono = queue.tryTransfer("data");
// or try transfer up to 10 seconds
Mono<Boolean> mono = queue.tryTransfer("data", 10, TimeUnit.SECONDS);

// in other thread or JVM

Mono<String> mono = queue.take();
// or
Mono<String> mono = queue.poll();

mono.doOnNext(res -> {
   // ...
}).subscribe();

Code example of RxJava2 interface usage:

RedissonRxClient redisson = Redisson.createRx(config);
RTransferQueueRx<String> queue = redisson.getTransferQueue("myCountDownLatch");

Completable res = queue.transfer("data");
// or try transfer immediately
Single<Boolean> resRx = queue.tryTransfer("data");
// or try transfer up to 10 seconds
Single<Boolean> resRx = queue.tryTransfer("data", 10, TimeUnit.SECONDS);

// in other thread or JVM

Single<String> resRx = queue.take();
// or
Maybe<String> resRx = queue.poll();

resRx.doOnSuccess(res -> {
   // ...
}).subscribe();

kq1983

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