E - the type of the elements in the ringbuffer.public class RingbufferProxy<E> extends AbstractDistributedObject<RingbufferService> implements Ringbuffer<E>
Ringbuffer.| Modifier and Type | Field and Description |
|---|---|
static int |
MAX_BATCH_SIZE
The maximum number of items that can be retrieved in 1 go using the
readManyAsync(long, int, int, IFunction)
method. |
PARTITIONING_STRATEGY| Constructor and Description |
|---|
RingbufferProxy(NodeEngine nodeEngine,
RingbufferService service,
String name,
RingbufferConfig config) |
| Modifier and Type | Method and Description |
|---|---|
long |
add(E item)
Adds an item to the tail of the Ringbuffer.
|
ICompletableFuture<Long> |
addAllAsync(Collection<? extends E> collection,
OverflowPolicy overflowPolicy)
Adds all the items of a collection to the tail of the Ringbuffer.
|
ICompletableFuture<Long> |
addAsync(E item,
OverflowPolicy overflowPolicy)
Asynchronously writes an item with a configurable
OverflowPolicy. |
long |
capacity()
Returns the capacity of this Ringbuffer.
|
String |
getName()
Returns the unique name for this DistributedObject.
|
int |
getPartitionId() |
String |
getServiceName()
Returns the service name for this object.
|
long |
headSequence()
Returns the sequence of the head.
|
ICompletableFuture<ReadResultSet<E>> |
readManyAsync(long startSequence,
int minCount,
int maxCount,
IFunction<E,Boolean> filter)
Reads a batch of items from the Ringbuffer.
|
E |
readOne(long sequence)
Reads one item from the Ringbuffer.
|
long |
remainingCapacity()
Returns the remaining capacity of the ringbuffer.
|
long |
size()
Returns number of items in the Ringbuffer.
|
long |
tailSequence()
Returns the sequence of the tail.
|
String |
toString() |
destroy, equals, getDistributedObjectName, getNameAsPartitionAwareData, getNodeEngine, getOperationService, getPartitionId, getPartitionKey, getService, hashCode, invalidate, invokeOnPartition, isClusterVersionEqualTo, isClusterVersionGreaterOrEqual, isClusterVersionGreaterThan, isClusterVersionLessOrEqual, isClusterVersionLessThan, isClusterVersionUnknown, isClusterVersionUnknownOrGreaterOrEqual, isClusterVersionUnknownOrGreaterThan, isClusterVersionUnknownOrLessOrEqual, isClusterVersionUnknownOrLessThan, postDestroy, preDestroy, throwNotActiveException, toDataclone, finalize, getClass, notify, notifyAll, wait, wait, waitdestroy, getPartitionKeypublic static final int MAX_BATCH_SIZE
readManyAsync(long, int, int, IFunction)
method.public RingbufferProxy(NodeEngine nodeEngine, RingbufferService service, String name, RingbufferConfig config)
public int getPartitionId()
public String getName()
DistributedObjectDistributedObjectUtil.getName(DistributedObject)
because this might be also a PrefixedDistributedObject.getName in interface DistributedObjectpublic String getServiceName()
DistributedObjectgetServiceName in interface DistributedObjectgetServiceName in class AbstractDistributedObject<RingbufferService>public long capacity()
Ringbuffercapacity in interface Ringbuffer<E>public long size()
RingbufferIf no ttl is set, the size will always be equal to capacity after the head completed the first loop around the ring. This is because no items are getting retired.
size in interface Ringbuffer<E>public long tailSequence()
RingbufferThe initial value of the tail is -1 if the Ringbuffer is not backed by a store, otherwise tail sequence will be set to the sequence of the previously last stored item.
tailSequence in interface Ringbuffer<E>public long headSequence()
RingbufferIf the RingBuffer is empty, the head will be one more than the tail.
The initial value of the head is 0 if the Ringbuffer is not backed by a store, otherwise head sequence will be set to the sequence of the previously last stored item + 1. In both cases head sequence is 1 more than the tail sequence.
headSequence in interface Ringbuffer<E>public long remainingCapacity()
RingbufferThe returned value could be stale as soon as it is returned.
If ttl is not set, the remaining capacity will always be the capacity.
remainingCapacity in interface Ringbuffer<E>public long add(E item)
RingbufferRingbuffer.addAsync(Object, OverflowPolicy) and the OverflowPolicy.
The returned value is the sequence of the added item. Using this sequence you can read the added item.
If the Ringbuffer is backed by a RingbufferStore,
the item gets persisted by the underlying store via
RingbufferStore.store(long, Object). Note that
in case an exception is thrown by the store, it prevents the item from being
added to the Ringbuffer, keeping the store, primary and the backups
consistent.
add in interface Ringbuffer<E>item - the item to add.Ringbuffer.addAsync(Object, OverflowPolicy)public ICompletableFuture<Long> addAsync(E item, OverflowPolicy overflowPolicy)
RingbufferOverflowPolicy.
If there is space in the Ringbuffer, the call will return the sequence of the written item. If there is no space, it depends on the overflow policy what happens:
OverflowPolicy.OVERWRITE: we just overwrite the oldest item
in the Ringbuffer and we violate the ttlOverflowPolicy.FAIL: we return -1 The reason that FAIL exist is to give the opportunity to obey the ttl. If blocking behavior is required, this can be implemented using retrying in combination with an exponential backoff. Example:
long sleepMs = 100;
for (; ; ) {
long result = ringbuffer.addAsync(item, FAIL).get();
if (result != -1) {
break;
}
TimeUnit.MILLISECONDS.sleep(sleepMs);
sleepMs = min(5000, sleepMs * 2);
}
If the Ringbuffer is backed by a RingbufferStore,
the item gets persisted by the underlying store via
RingbufferStore.store(long, Object). Note
that in case an exception is thrown by the store, it prevents the item
from being added to the Ringbuffer, keeping the store, primary and the
backups consistent.
addAsync in interface Ringbuffer<E>item - the item to addoverflowPolicy - the OverflowPolicy to use.public E readOne(long sequence) throws InterruptedException
RingbufferIf the sequence is one beyond the current tail, this call blocks until an item is added. This means that the ringbuffer can be processed using the following idiom:
Ringbuffer<String> ringbuffer = hz.getRingbuffer("rb");
long seq = ringbuffer.headSequence();
while(true){
String item = ringbuffer.readOne(seq);
seq++;
... process item
}
This method is not destructive unlike e.g. a queue.take. So the same item can be read by multiple readers or it can be read multiple times by the same reader.
Currently it isn't possible to control how long this call is going to
block. In the future we could add e.g.
tryReadOne(long sequence, long timeout, TimeUnit unit).
If the item is not in the Ringbuffer an attempt is made to read it from
the underlying RingbufferStore via
RingbufferStore.load(long) if store is
configured for the Ringbuffer. These cases may increase the execution time
significantly depending on the implementation of the store. Note that
exceptions thrown by the store are propagated to the caller.
readOne in interface Ringbuffer<E>sequence - the sequence of the item to read.InterruptedException - if the call is interrupted while blocking.public ICompletableFuture<Long> addAllAsync(Collection<? extends E> collection, OverflowPolicy overflowPolicy)
Ringbuffer
An addAll is likely to outperform multiple calls to Ringbuffer.add(Object)
due to better io utilization and a reduced number of executed operations.
If the batch is empty, the call is ignored.
When the collection is not empty, the content is copied into a different data-structure. This means that:
If the collection is larger than the capacity of the Ringbuffer, then the items that were written first will be overwritten. Therefore this call will not block.
The items are inserted in the order of the Iterator of the collection. If an addAll is executed concurrently with an add or addAll, no guarantee is given that items are contiguous.
The result of the future contains the sequenceId of the last written item.
If the Ringbuffer is backed by a RingbufferStore,
the items are persisted by the underlying store via
RingbufferStore.storeAll(long, Object[]).
Note that in case an exception is thrown by the store, it makes the
Ringbuffer not adding any of the items to the primary and the backups.
Keeping the store consistent with the primary and the backups is the
responsibility of the store.
addAllAsync in interface Ringbuffer<E>collection - the batch of items to add.public ICompletableFuture<ReadResultSet<E>> readManyAsync(long startSequence, int minCount, int maxCount, IFunction<E,Boolean> filter)
RingbuffermaxCount,
these items are returned. So it could be the number of items read is
smaller than the maxCount.
If there are less items available than minCount, then this call
blocks.
Reading a batch of items is likely to perform better because less overhead is involved.
A filter can be provided to only select items that need to be read. If the filter is null, all items are read. If the filter is not null, only items where the filter function returns true are returned. Using filters is a good way to prevent getting items that are of no value to the receiver. This reduces the amount of IO and the number of operations being executed, and can result in a significant performance improvement.
For each item not available in the Ringbuffer an attempt is made to read
it from the underlying RingbufferStore via
multiple invocations of RingbufferStore.load(long),
if store is configured for the Ringbuffer. These cases may increase the
execution time significantly depending on the implementation of the store.
Note that exceptions thrown by the store are propagated to the caller.
readManyAsync in interface Ringbuffer<E>startSequence - the startSequence of the first item to read.minCount - the minimum number of items to read.maxCount - the maximum number of items to read.filter - the filter. Filter is allowed to be null, indicating
there is no filter.public String toString()
toString in class AbstractDistributedObject<RingbufferService>Copyright © 2018 Hazelcast, Inc.. All Rights Reserved.