import Replicator from '@cansat-icarus/capture-lib/src/icarus/backend/replicator.js'

public class | source

Replicator

Extends:

events~EventEmitter → Replicator

Handles replication between a local and remote PouchDB database. Keeps track of state, uses an ExponentialBackoff to prevent connection saturation, serving as a wrapper over PouchDB replication.

The source database is set once in the constructor and remains unchanged and unchangeable during operation.

Constructor Summary

Public Constructor
public	constructor(logger: Logger, sourceDB: PouchDB)

Member Summary

Private Members
private	_backoff: ExponentialBackoff ExponentialBackoff instance.
private	_log: Bunyan Logger instance.
private	_replication: PouchDBReplicationID PouchDB replication instance/ID.
private	_sourceDB: PouchDB Source database.
private	_state: String Replicator status.
private	_targetDB: PouchDB Target database.

Method Summary

Public Methods
public	async cleanup(): Promise Stops current replication and attempts last-minute replication.
public	replicate(dbName: String, username: String, password: String): Promise Starts replication to a remote database.
public	stop() Stops the replication process.

Private Methods
private	_cancelCurrentReplicator()
private	_createReplicator(opts: Object): PouchDBReplicationID Creates a new PouchDB replicator.
private	_ensureReplication(retry: Number) Restarts the replication process when unintentionally stopped.
private	_updateState(state: String, moreLogData: Object) Updates the Replicator's Replicator#_state.

Public Constructors

public constructor(logger: Logger, sourceDB: PouchDB) source

Params:

Name	Type	Attribute	Description
logger	Logger		Bunyan logger instance.
sourceDB	PouchDB		Database to be replicated.

Private Members

private _backoff: ExponentialBackoff source

ExponentialBackoff instance. Keeps track of the replication backoff.

private _log: Bunyan source

Logger instance.

private _replication: PouchDBReplicationID source

PouchDB replication instance/ID.

private _sourceDB: PouchDB source

Source database.

private _state: String source

Replicator status.

private _targetDB: PouchDB source

Target database.

Public Methods

public async cleanup(): Promise source

Stops current replication and attempts last-minute replication. Last-minute replication is done in "one-shot" mode: replicates whatever data it has and immediately stops without listening for changes in the local database.

Return:

Promise

Emit:

*	state('cleanup')

public replicate(dbName: String, username: String, password: String): Promise source

Starts replication to a remote database.

Params:

Name	Type	Attribute	Description
dbName	String		Name/URL of the remote database.
username	String	optional	Database username, if applicable.
password	String	optional	Database password, if applicable.

Return:

Promise

resolved when the replication connection succeeds for the first time.

Emit:

*	state(state): the state of the replicator.

public stop() source

Stops the replication process.

Emit:

*	state('inactive')

Private Methods

private _cancelCurrentReplicator() source

private _createReplicator(opts: Object): PouchDBReplicationID source

Creates a new PouchDB replicator. Remember that this class is simply a wrapper.

Params:

Name	Type	Attribute	Description
opts	Object	optional	PouchDB replication options.
opts.live	Boolean	optional default: true	Keep the replication running, pushing changes as they happen.
opts.retry	Boolean	optional default: false	Enable PouchDB's built-in backoff algorithm.

Return:

PouchDBReplicationID

private _ensureReplication(retry: Number) source

Restarts the replication process when unintentionally stopped.

Params:

Name	Type	Attribute	Description
retry	Number		Retry counter

private _updateState(state: String, moreLogData: Object) source

Updates the Replicator's Replicator#_state.

Params:

Name	Type	Attribute	Description
state	String		New state.
moreLogData	Object	optional	Extra data to be included in the log.

Emit:

*	state(state)