liara.cache

Module Contents

Classes

CacheInfo	Information about a cache. Note that the information can be approximated as getting the exact numbers may be costly.
Cache	Interface for key-value caches.
FilesystemCache	A Cache implementation which uses the filesystem to cache data.
Sqlite3Cache	A Cache implementation which uses SQLite to store the data. This is mostly useful if creating many files is slow, for instance due to anti-virus software.
MemoryCache	An in-memory Cache implementation.
RedisCache	A cache using Redis as the storage backend.
NullCache	The null cache drops all requests and does not cache any data.

API

class liara.cache.CacheInfo

Information about a cache. Note that the information can be approximated as getting the exact numbers may be costly.

size: int = 0

Approximate number of bytes stored in the cache.

entry_count: int = 0

Approximate number of objects stored in the cache.

name: str = <Multiline-String>

A human-friendly name for this cache.

class liara.cache.Cache

Bases: abc.ABC

Interface for key-value caches.

abstractmethod set_key_prefix(prefix: bytes)

Set a prefix for all keys. This can be for example used to avoid collisions when the configuration changes (which can impact all values).

abstractmethod put(key: bytes, value: object | bytes) → bool

Put a value into the cache using the provided key.

Parameters:

• key – The key under which value will be stored.

• value – A pickable Python object to be stored, or raw bytes.

Returns:

True if the value was added to the cache, False if it was already cached.

abstractmethod get(key: bytes) → Optional[object | bytes]

Get a stored object.

Parameters:

key – The object key.

Returns:

An object if one exists. Otherwise, return None.

persist() → None

Persists this cache to disk/persistent storage.

This function should be called after the cache has been populated. On the next run, the constructor will then pick up the index and return cached data.

abstractmethod clear() → None

Clear the contents of the cache.

Added in version 2.5.

abstractmethod inspect() → liara.cache.CacheInfo

Get an overview of the cached data.

Added in version 2.5.

class liara.cache.FilesystemCache(path: pathlib.Path)

Bases: liara.cache._CacheBase

A Cache implementation which uses the filesystem to cache data.

This cache tries to load a previously generated index. Use persist() to write the cache index to disk.

Initialization

clear() → None

persist()

inspect()

class liara.cache.Sqlite3Cache(path: pathlib.Path)

Bases: liara.cache._CacheBase

A Cache implementation which uses SQLite to store the data. This is mostly useful if creating many files is slow, for instance due to anti-virus software.

This cache tries to load a previously generated index. Use persist() to write the cache index to disk.

Initialization

clear() → None

persist()

inspect()

class liara.cache.MemoryCache

Bases: liara.cache._CacheBase

An in-memory Cache implementation.

This cache stores all objects in-memory.

Initialization

clear()

inspect()

class liara.cache.RedisCache(host: str, port: int, db: int, expiration_time=timedelta(hours=1))

Bases: liara.cache._CacheBase

A cache using Redis as the storage backend.

Initialization

clear()

inspect()

class liara.cache.NullCache

Bases: liara.cache._CacheBase

The null cache drops all requests and does not cache any data.

This is mostly useful to disable caching in APIs which require a cache instance.

Initialization

clear() → None

inspect() → liara.cache.CacheInfo