com.hazelcast.spi.impl.sequence

Class CallIdSequenceWithBackpressure

java.lang.Object

com.hazelcast.spi.impl.sequence.CallIdSequenceWithBackpressure

All Implemented Interfaces:

CallIdSequence

public final class CallIdSequenceWithBackpressure
extends Object
implements CallIdSequence

A CallIdSequence that provides backpressure by taking the number of in-flight operations into account when before creating a new call-id.

It is possible to temporarily create more concurrent invocations than the declared capacity due to:

• system operations
• the racy nature of checking if space is available and getting the next sequence.

The latter cause is not a problem since the capacity is exceeded temporarily and it isn't sustainable. So perhaps there are a few threads that at the same time see that the there is space and do a next. But any following invocation needs to wait till there is is capacity.

Constructor Summary

Constructors

Constructor and Description
CallIdSequenceWithBackpressure(int maxConcurrentInvocations, long backoffTimeoutMs)

Method Summary

Modifier and Type	Method and Description
void	complete() Not idempotent: must be called exactly once per invocation.
long	forceNext() Generates the next unique call ID.
long	getLastCallId() Returns the last issued call ID.
int	getMaxConcurrentInvocations() Returns the maximum concurrent invocations supported.
long	next() Generates the next unique call ID.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CallIdSequenceWithBackpressure

public CallIdSequenceWithBackpressure(int maxConcurrentInvocations,
                                      long backoffTimeoutMs)

Method Detail

getLastCallId

public long getLastCallId()

Description copied from interface: CallIdSequence

Returns the last issued call ID. ONLY FOR TESTING. Must not be used for production code.

Specified by:

getLastCallId in interface CallIdSequence

getMaxConcurrentInvocations

public int getMaxConcurrentInvocations()

Description copied from interface: CallIdSequence

Returns the maximum concurrent invocations supported. Integer.MAX_VALUE means there is no max.

Specified by:

getMaxConcurrentInvocations in interface CallIdSequence

Returns:

the maximum concurrent invocation.

next

public long next()
          throws TimeoutException

Description copied from interface: CallIdSequence

Generates the next unique call ID. When the implementation supports backpressure, it will not return unless the number of outstanding invocations is within the configured limit. Instead it will block until the condition is met and eventually throw a timeout exception.

Specified by:

next in interface CallIdSequence

Returns:

the generated call ID

Throws:

TimeoutException - if the outstanding invocation count hasn't dropped below the configured limit within the configured timeout

complete

public void complete()

Description copied from interface: CallIdSequence

Not idempotent: must be called exactly once per invocation.

Specified by:

complete in interface CallIdSequence

forceNext

public long forceNext()

Description copied from interface: CallIdSequence

Generates the next unique call ID. This never blocks and it should be used only for urgent operation or when retrying.

Specified by:

forceNext in interface CallIdSequence

Returns:

the generated call ID