MemcachedLock

Extends: Lock

Implements: IConfigurable, IReferenceable, IOpenable

Description

The MemcachedLock class allows you to create a lock that is implemented based on the Memcached’s caching service.

Important points

• The current implementation does not support authentication.

Configuration parameters

• connection(s):
  • discovery_key: (optional) key to retrieve the connection from IDiscovery
  • host: host name or IP address
  • port: port number
  • uri: resource URI or connection string with all parameters in it
• options:
  • max_size: maximum number of values stored in this cache (default: 1000)
  • max_key_size: maximum key length (default: 250)
  • max_expiration: maximum expiration duration in milliseconds (default: 2592000)
  • max_value: maximum value length (default: 1048576)
  • pool_size: pool size (default: 5)
  • reconnect: reconnection timeout in milliseconds (default: 10 sec)
  • retries: number of retries (default: 3)
  • timeout: default caching timeout in milliseconds (default: 1 minute)
  • failures: number of failures before stop retrying (default: 5)
  • retry: retry timeout in milliseconds (default: 30 sec)
  • idle: idle timeout before disconnect in milliseconds (default: 5 sec)

References

• *:discovery:*:*:1.0 - (optional) IDiscovery services to resolve connection

Instance methods

close

Closes a component and frees used resources.

public close(correlationId: string): Promise<void>

• correlationId: string - (optional) transaction id used to trace execution through the call chain.

configure

Configures a component by passing its configuration parameters.

public configure(config: ConfigParams): void

• config: ConfigParams - configuration parameters to be set.

isOpen

Checks if the component is open.

public isOpen(): boolean

• returns: boolean - true if the component is open and false otherwise.

open

Opens the component.

public open(correlationId: string): Promise<void>

• correlationId: string - (optional) transaction id usd to trace execution through the call chain.

releaseLock

Releases a prevously acquired lock by its key.

public releaseLock(correlationId: string, key: string): Promise<void>

• correlationId: string - (optional) transaction id used to trace execution through the call chain.
• key: string - unique lock key to release.

setReferences

Sets references to dependent components.

public setReferences(references: IReferences): void

• references: IReferences - references to locate the component’s dependencies.

tryAcquireLock

Makes a single attempt to acquire a lock by its key. It returns immediately a positive or negative result.

public tryAcquireLock(correlationId: string, key: string, ttl: number): Promise<boolean>

• correlationId: string - (optional) transaction id used to trace execution through the call chain.
• key: string - unique lock key to acquire.
• ttl: number - lock timeout (time to live) in milliseconds.
• returns: Promise<boolean> - true if lock was successfull and false otherwise.

Examples

let lock = new MemcachedLock();
lock.configure(ConfigParams.fromTuples(
  "host", "localhost",
  "port", 11211
));
await lock.open("123");
await lock.acquire("123", "key1");
try {
  // Processing...
} finally {
  await lock.releaseLock("123", "key1");
}