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Version: v1.0.0-rc1 Latest Latest
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Published: Nov 5, 2015 License: Apache-2.0 Imports: 7 Imported by: 0

Documentation

Overview

Package mode defines and implents output strategies with failover or load balancing modes for use by output plugins.

Index

Constants

This section is empty.

Variables

View Source
var (
	// ErrNoConnectionConfigured indicates no configured connections for publishing.
	ErrNoConnectionConfigured = errors.New("No connection configured")
)
View Source
var ErrNoHostsConfigured = errors.New("no host configuration found")

ErrNoHostsConfigured indicates missing host or hosts configuration

View Source
var (
	// ErrTempBulkFailure indicates PublishEvents fail temporary to retry.
	ErrTempBulkFailure = errors.New("temporary bulk send failure")
)

Functions

This section is empty.

Types

type ConnectionMode

type ConnectionMode interface {
	// Close will stop the modes it's publisher loop and close all it's
	// associated clients
	Close() error

	// PublishEvents will send all events (potentially asynchronous) to its
	// clients.
	PublishEvents(trans outputs.Signaler, events []common.MapStr) error

	// PublishEvent will send an event to its clients.
	PublishEvent(trans outputs.Signaler, event common.MapStr) error
}

ConnectionMode takes care of connecting to hosts and potentially doing load balancing and/or failover

type FailOverConnectionMode

type FailOverConnectionMode struct {
	// contains filtered or unexported fields
}

FailOverConnectionMode connects to at most one host by random and swap to another host (by random) if currently active host becomes unavailable. If no connection is available, the mode blocks until a new connection can be established.

func NewFailOverConnectionMode

func NewFailOverConnectionMode(
	clients []ProtocolClient,
	maxAttempts int,
	waitRetry, timeout time.Duration,
) (*FailOverConnectionMode, error)

NewFailOverConnectionMode creates a new failover connection mode leveraging only one connection at once. If connection becomes unavailable, the mode will try to connect to another configured connection.

func (*FailOverConnectionMode) Close

func (f *FailOverConnectionMode) Close() error

Close closes the active connection.

func (*FailOverConnectionMode) PublishEvent

func (f *FailOverConnectionMode) PublishEvent(
	signaler outputs.Signaler,
	event common.MapStr,
) error

PublishEvent forwards a single event. On failure PublishEvent tries to reconnect.

func (*FailOverConnectionMode) PublishEvents

func (f *FailOverConnectionMode) PublishEvents(
	signaler outputs.Signaler,
	events []common.MapStr,
) error

PublishEvents tries to publish the events with retries if connection becomes unavailable. On failure PublishEvents tries to connect to another configured connection by random.

type LoadBalancerMode

type LoadBalancerMode struct {
	// contains filtered or unexported fields
}

LoadBalancerMode balances the sending of events between multiple connections.

The balancing algorithm is mostly pull-based, with multiple workers trying to pull some amount of work from a shared queue. Workers will try to get a new work item only if they have a working/active connection. Workers without active connection do not participate until a connection has been re-established. Due to the pull based nature the algorithm will load-balance events by random with workers having less latencies/turn-around times potentially getting more work items then other workers with higher latencies. Thusly the algorithm dynamically adapts to resource availability of server events are forwarded to.

Workers not participating in the load-balancing will continuously try to reconnect to their configured endpoints. Once a new connection has been established, these workers will participate in in load-balancing again.

If a connection becomes unavailable, the events are rescheduled for another connection to pick up. Rescheduling events is limited to a maximum number of send attempts. If events have not been send after maximum number of allowed attemps has been passed, they will be dropped.

Distributing events to workers is subject to timeout. If no worker is available to pickup a message for sending, the message will be dropped internally.

func NewLoadBalancerMode

func NewLoadBalancerMode(
	clients []ProtocolClient,
	maxAttempts int,
	waitRetry, timeout, maxWaitRetry time.Duration,
) (*LoadBalancerMode, error)

NewLoadBalancerMode create a new load balancer connection mode.

func (*LoadBalancerMode) Close

func (m *LoadBalancerMode) Close() error

Close stops all workers and closes all open connections. In flight events are signaled as failed.

func (*LoadBalancerMode) PublishEvent

func (m *LoadBalancerMode) PublishEvent(
	signaler outputs.Signaler,
	event common.MapStr,
) error

PublishEvent forwards the event to some load balancing worker.

func (*LoadBalancerMode) PublishEvents

func (m *LoadBalancerMode) PublishEvents(
	signaler outputs.Signaler,
	events []common.MapStr,
) error

PublishEvents forwards events to some load balancing worker.

type ProtocolClient

type ProtocolClient interface {
	// Connect establishes a connection to the clients sink.
	// The connection attempt shall report an error if no connection could been
	// established within the given time interval. A timeout value of 0 == wait
	// forever.
	Connect(timeout time.Duration) error

	// Close closes the established connection.
	Close() error

	// IsConnected indicates the clients connection state. If connection has
	// been lost while publishing events, IsConnected must return false. As long as
	// IsConnected returns false, an output plugin might try to re-establish the
	// connection by calling Connect.
	IsConnected() bool

	// PublishEvents sends events to the clients sink. On failure or timeout err
	// must be set. If connection has been lost, IsConnected must return false
	// in future calls.
	// PublishEvents is free to publish only a subset of given events, even in
	// error case. On return nextEvents contains all events not yet published.
	PublishEvents(events []common.MapStr) (nextEvents []common.MapStr, err error)

	// PublishEvent sends one event to the clients sink. On failure and error is
	// returned.
	PublishEvent(event common.MapStr) error
}

ProtocolClient interface is a output plugin specific client implementation for encoding and publishing events. A ProtocolClient must be able to connection to it's sink and indicate connection failures in order to be reconnected byte the output plugin.

func MakeClients

func MakeClients(
	config outputs.MothershipConfig,
	newClient func(string) (ProtocolClient, error),
) ([]ProtocolClient, error)

MakeClients will create a list from of ProtocolClient instances from outputer configuration host list and client factory function.

type SingleConnectionMode

type SingleConnectionMode struct {
	// contains filtered or unexported fields
}

SingleConnectionMode sends all Output on one single connection. If connection is not available, the output plugin blocks until the connection is either available again or the connection mode is closed by Close.

func NewSingleConnectionMode

func NewSingleConnectionMode(
	client ProtocolClient,
	maxAttempts int,
	waitRetry, timeout, maxWaitRetry time.Duration,
) (*SingleConnectionMode, error)

NewSingleConnectionMode creates a new single connection mode using exactly one ProtocolClient connection.

func (*SingleConnectionMode) Close

func (s *SingleConnectionMode) Close() error

Close closes the underlying connection.

func (*SingleConnectionMode) PublishEvent

func (s *SingleConnectionMode) PublishEvent(
	signaler outputs.Signaler,
	event common.MapStr,
) error

PublishEvent forwards a single event. On failure PublishEvent tries to reconnect.

func (*SingleConnectionMode) PublishEvents

func (s *SingleConnectionMode) PublishEvents(
	signaler outputs.Signaler,
	events []common.MapStr,
) error

PublishEvents tries to publish the events with retries if connection becomes unavailable. On failure PublishEvents tries to reconnect.

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