https://github.com/gertjanvanzwieten/stash

Stash: stable hash and object stash
https://github.com/gertjanvanzwieten/stash

Last synced: 3 months ago
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Stash: stable hash and object stash

• Host: GitHub
• URL: https://github.com/gertjanvanzwieten/stash
• Owner: gertjanvanzwieten
• License: mit
• Created: 2024-10-11T15:26:33.000Z (9 months ago)
• Default Branch: main
• Last Pushed: 2024-10-12T08:58:20.000Z (8 months ago)
• Last Synced: 2024-10-29T00:06:49.544Z (8 months ago)
• Language: Rust
• Homepage:
• Size: 16.6 KB
• Stars: 1
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

• awesome-iroh - Stash - A pickle alternative that stores objects in a central database. (Utilities)

README

        
# Stash: stable hash and object stash

Stash is a pickle alternative that stores objects in a central database.

Like the equivalent pickle functions, `stash.dumps` returns a byte sequence

that can be loaded back via `stash.loads`; only the stash sequence is a fixed

length handle into the database. As handles are stable, the same mechanism can

be used to generate hashes for arbitrary Python objects, optionally combined

with a null database if deserialization is not required.

The key advantage of central storage is deduplication: objects that are stashed

twice are stored once. This applies at any level of nesting, as contained

objects are stashed recursively. This makes stash particularly well suited for

caching purposes, where individual serializations might result in excessive

duplication.

The hash itself can be useful in memoization strategies. Unlike Python's

built-in hash function, stash hashes are stable between restarts and not

limited to immutable objects, which allows them to be used for the persistent

storage of a much wider class of function arguments.

## Example

```python

>>> import stash

>>> db = stash.FsDB('/path/to/db/')

>>> obj = ['foo', {'bar': 'baz'}]

>>> h = db.dumps(obj)

>>> db.loads(h) == obj

True

```

## Differences to pickle

Stash differs from pickle in a number of important ways.

- Dictionary insertion order is not preserved.

  Stash upholds the rule that the hash of two objects must be equal if the

  objects test equal. Since dictionary equality in Python disregards the

  insertion order, this implies that stash cannot preserve it.

- Object identities are not preserved

  When a Python object contains multiple references to a second object, pickle

  preserves that these references are "is" rather than "==" identical and

  unpickles accordingly. Stash deserializes all objects as individual copies,

  with the exception of immutable types such as integers and strings.