MemcachedCache

Implements: ICache, IConfigurable, IReferenceable, IOpenable

Description

The MemcachedCache class allows you to create distributed cache that stores values in 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.

close(correlation_id: Optional[str])

• correlation_id: Optional[str] - (optional) transaction id used to trace execution through the call chain.

configure

Configures a component by passing its configuration parameters.

configure(config: ConfigParams)

• config: ConfigParams - configuration parameters to be set.

is_open

Checks if the component is open.

is_open(): bool

• returns: bool - true if the component has been opened and false otherwise.

open

Opens the component.

open(correlation_id: Optional[str])

• correlation_id: Optional[str] - (optional) transaction id used to trace execution through the call chain.

remove

Removes a value from the cache by its key.

remove(correlation_id: Optional[str], key: str): Any

• correlation_id: Optional[str] - (optional) transaction id used to trace execution through the call chain.
• key: str - unique value key.
• return: Any - deleted value.

retrieve

Retrieves a cached value from the cache using its key. If the value is missing in the cache or expired, it returns None.

retrieve(correlation_id: Optional[str], key: str): Any

• correlation_id: Optional[str] - (optional) transaction id used to trace execution through the call chain.
• key: str - unique value key.
• return: Any - cached value or None if nothing was found.

set_references

Sets references to dependent components.

set_references(references: IReferences)

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

store

Stores a value in the cache with an expiration time.

store(correlation_id: Optional[str], key: str, value: Any, timeout: int): Any

• correlation_id: Optional[str] - (optional) transaction id used to trace execution through the call chain.
• key: str - unique value key.
• value: Any - value to store.
• timeout: int - expiration timeout in milliseconds.
• returns: Any - stored value

Examples

cache = MemcachedCache()
cache.configure(ConfigParams.from_tuples(
    "connection.host", "localhost",
    "connection.port", 11211
))
        
cache.open("123")
        
cache.store("123", "key1", "ABC", 5000)
value = cache.retrieve("123", "key1", )  # Result: "ABC"