org.swisspush.gateleen.queue.queuing.circuitbreaker

Interface QueueCircuitBreaker

All Known Implementing Classes:

QueueCircuitBreakerImpl

public interface QueueCircuitBreaker

The QueueCircuitBreaker monitors the queue activity and protects the system from too much load when circuits/endpoints are not reachable.

Author:

https://github.com/mcweba [Marc-Andre Weber]

Method Summary

Modifier and Type	Method and Description
io.vertx.core.Future<Void>	closeAllCircuits() Closes all non-closed circuits.
io.vertx.core.Future<Void>	closeCircuit(HttpRequest queuedRequest) Closes the circuit representing the queued request.
io.vertx.core.Future<QueueCircuitState>	handleQueuedRequest(String queueName, HttpRequest queuedRequest) Handles a queued request by checking the current QueueCircuitState of the corresponding circuit.
boolean	isCircuitCheckEnabled() Check whether the circuit check is enabled.
boolean	isStatisticsUpdateEnabled() Check whether the statistics update is enabled.
io.vertx.core.Future<Void>	lockQueue(String queueName, HttpRequest queuedRequest) Locks the queue having the provided queueName by calling the vertx-redisques API.
io.vertx.core.Future<Void>	reOpenCircuit(HttpRequest queuedRequest) Re-Opens the (half-open) circuit representing the provided queued request again.
io.vertx.core.Future<Long>	setOpenCircuitsToHalfOpen() Changes the status of all circuits having a status equals QueueCircuitState.OPEN to QueueCircuitState.HALF_OPEN.
io.vertx.core.Future<String>	unlockNextQueue() Unlocks the next queue in-line.
io.vertx.core.Future<String>	unlockQueue(String queueName) Unlocks the queue having the provided queueName by calling the vertx-redisques API.
io.vertx.core.Future<Long>	unlockSampleQueues() Unlocks a sample queue of all circuits having a status equals QueueCircuitState.HALF_OPEN.
io.vertx.core.Future<Void>	updateStatistics(String queueName, HttpRequest queuedRequest, QueueResponseType queueResponseType) Updates the statistics of the corresponding circuit based on the provided request to execute.

Method Detail

handleQueuedRequest

io.vertx.core.Future<QueueCircuitState> handleQueuedRequest(String queueName,
                                                            HttpRequest queuedRequest)

Handles a queued request by checking the current QueueCircuitState of the corresponding circuit. When the QueueCircuitState of the corresponding circuit equals QueueCircuitState.OPEN, the provided queueName will be locked.

Parameters:

queueName - the name of the queue

queuedRequest - the queued request

Returns:

returns a QueueCircuitState representing the current status of the circuit

updateStatistics

io.vertx.core.Future<Void> updateStatistics(String queueName,
                                            HttpRequest queuedRequest,
                                            QueueResponseType queueResponseType)

Updates the statistics of the corresponding circuit based on the provided request to execute.

Updating the statistics includes the following steps:

• Record queuedRequest as failed when queueResponseType equals QueueResponseType.FAILURE
• Record queuedRequest as success when queueResponseType equals QueueResponseType.SUCCESS
• Calculate failRatio based on fail/success records
• Change status of corresponding circuit to 'OPEN' when failRatio threshold is reached

Parameters:

queueName - the name of the queue

queuedRequest - the queued request

queueResponseType - the QueueResponseType representing the execution result of the queuedRequest

Returns:

returns a void future when statistics could be updated successfully.

isCircuitCheckEnabled

boolean isCircuitCheckEnabled()

Check whether the circuit check is enabled. The circuit check can be enabled/disabled with the 'circuitCheckEnabled' configuration property.

Returns:

returns true when circuit check is enabled, false otherwise

isStatisticsUpdateEnabled

boolean isStatisticsUpdateEnabled()

Check whether the statistics update is enabled. The statistics update can be enabled/disabled with the 'statisticsUpdateEnabled' configuration property.

Returns:

returns true when statistics update is enabled, false otherwise

lockQueue

io.vertx.core.Future<Void> lockQueue(String queueName,
                                     HttpRequest queuedRequest)

Locks the queue having the provided queueName by calling the vertx-redisques API. Additionally, marks the queueName as a locked queue of the circuit representing the provided queuedRequest.

Parameters:

queueName - the name of the queue

queuedRequest - the queued request

Returns:

returns a void future when the queue could be locked successfully through vertx-redisques and also successfully marked as a locked queue of the circuit.

unlockQueue

io.vertx.core.Future<String> unlockQueue(String queueName)

Unlocks the queue having the provided queueName by calling the vertx-redisques API.

Parameters:

queueName - the name of the queue

Returns:

returns a string future holding the name of the queue when successfully unlocked. Also returns the name of the queue (as failureMessage) when the unlocking failed.

unlockNextQueue

io.vertx.core.Future<String> unlockNextQueue()

Unlocks the next queue in-line. Does nothing when there's no next queue to unlock. Returns a null string in this case.

Returns:

returns a string future holding the name of the queue which was successfully unlocked. Also returns the name of the queue (as failureMessage) when the next queue could not be unlocked. Returns a null string when no queue was available to unlock.

closeCircuit

io.vertx.core.Future<Void> closeCircuit(HttpRequest queuedRequest)

Closes the circuit representing the queued request.

Closing the circuit includes the following steps:

• Clear statistics of this circuit
• Reset failRatio of this circuit to zero
• Set status of this circuit to 'CLOSED'
• Unlock all queues related to this circuit

Parameters:

queuedRequest - the queued request

Returns:

returns a void future when circuit could be closed successfully.

closeAllCircuits

io.vertx.core.Future<Void> closeAllCircuits()

Closes all non-closed circuits.

Closing all non-closed circuits includes the following steps:

• Clear statistics of all non-closed circuits
• Reset failRatio of all non-closed circuits to zero
• Set status of all non-closed circuits to 'CLOSED'
• Unlock all queues related to all non-closed circuits

Returns:

returns a void future when all non-closed circuits could be closed successfully.

reOpenCircuit

io.vertx.core.Future<Void> reOpenCircuit(HttpRequest queuedRequest)

Re-Opens the (half-open) circuit representing the provided queued request again. Circuits should be re-opened after a sample queue request was not successful.

Parameters:

queuedRequest - the queued request

Returns:

returns a void future when the circuit representing the provided queued request could be re-opened successfully

setOpenCircuitsToHalfOpen

io.vertx.core.Future<Long> setOpenCircuitsToHalfOpen()

Changes the status of all circuits having a status equals QueueCircuitState.OPEN to QueueCircuitState.HALF_OPEN.

Returns:

returns a future holding the amount of circuits updated

unlockSampleQueues

io.vertx.core.Future<Long> unlockSampleQueues()

Unlocks a sample queue of all circuits having a status equals QueueCircuitState.HALF_OPEN. The sample queues are always the queues which have not been unlocked the longest.

Returns:

returns a future holding the amount of unlocked sample queues