juanitomint / cache_python_class

In memory cache with LRU (Least Recently Used) eviction policy

In memory cache implementation in python

This project implements a simple in memory cache implementation in python. With least accessed or lru_cache (Least Recently Used) eviction and replacement policy.

graph TD
  
subgraph "ADD KEY"
        X[X:0]
end
subgraph "cache (key:hits)"
    A[A:1]
    B[B:5]
    C[C:7]
    D[D:10]
    E[E:13]
end


subgraph "cache2(key:hits)"

    J[X:0]
    K[B:5]
    L[C:7]
    M[D:10]
    N[E:13]
end

subgraph "Evict key"
    Y[A:1]
end
  X -->|Added new key with value 55| A
  A --> |Evicted key 1 with 1 hits |Y
  A --> J

  

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Summary

The Cache class provides the following methods:

• init(self, size, hash_key="id", tabulate=tabulate): The constructor method that initializes the cache with the specified size, hash key, and tabulate function.
• put(self, data): Adds data to the cache. If the cache is full, it evicts the least recently used item. It calculates the hash of the data and updates the cache_hits and cache_dict accordingly.
• get(self, hash): Retrieves data from the cache based on the provided hash. It returns the data if it exists in the cache, otherwise it returns None.
• hash(self, data): Generates a hash for the provided data using the specified hash key.
• evict(self, hash): Evicts the item with the specified hash from the cache. It removes the item from cache_hits and cache_dict.

Installation

install dependencies using:

poetry install

basic usage

Initializes a cache object of size 10 and using "id" as cache key

cache = Cache(10,hash_key="id")
cache.put({
    "id": "6600b6418bf59b69902a95ca",
    "email": "[e-mail]",
    "roles": [
      "guest",
      "owner"
    ],
    "profile": {
      "dob": "1992-09-29",
      "name": "Pace Rivera",
      "about": "Anim cupidatat elit ut occaecat consectetur do nisi consequat mollit. Nisi officia dolore id esse velit.",
      "address": "22 Calder Place, Mooresburg, Missouri",
      "company": "Olucore",
      "location": {
        "lat": 26.236175,
        "long": 156.744712
      }
    },
    "username": "pace92",
    "createdAt": "2012-07-11T18:11:54.040Z",
    "updatedAt": "2012-07-12T18:11:54.040Z"
  })
cache.stats()

The script will print the output as below for cache hits

┌──────────────────────────────────┬────────┐
│ key                              │   Hits │
├──────────────────────────────────┼────────┤
│ 7557457053c85ce298cec0943ef005a9 │      0 │
├──────────────────────────────────┼────────┤
│ 5552c91d88f02d64fc5c505a5da99ef3 │      0 │
├──────────────────────────────────┼────────┤
│ 4facabbbb86de55456ab10a72e082a7a │      0 │
├──────────────────────────────────┼────────┤
│ 2ef1d6ba53f9d852668e0c46cd0d0b30 │      0 │
├──────────────────────────────────┼────────┤
│ 56cd508b04ac9a53aa2cdf68536d6963 │      0 │
├──────────────────────────────────┼────────┤
│ e8ee65dcdaf504a45ef717e3c111ed7d │      0 │
├──────────────────────────────────┼────────┤
│ bc8b811845ceaf9b14c0721d97c30691 │      0 │
├──────────────────────────────────┼────────┤
│ 785702be8401728d942075fbe2372b72 │      0 │
├──────────────────────────────────┼────────┤
│ 56e812dac283d0df19bada604f155367 │      0 │
├──────────────────────────────────┼────────┤
│ 3240bf8a1bd85d20b9ce611947fe879b │      0 │
└──────────────────────────────────┴────────┘

when adding next key with value 55 it will evict the least accessed key: 3240bf8a1bd85d20b9ce611947fe879b

┌──────────────────────────────────┬────────┐
│ key                              │   Hits │
├──────────────────────────────────┼────────┤
│ 7557457053c85ce298cec0943ef005a9 │      6 │
├──────────────────────────────────┼────────┤
│ 5552c91d88f02d64fc5c505a5da99ef3 │      8 │
├──────────────────────────────────┼────────┤
│ 4facabbbb86de55456ab10a72e082a7a │     13 │
├──────────────────────────────────┼────────┤
│ 2ef1d6ba53f9d852668e0c46cd0d0b30 │      9 │
├──────────────────────────────────┼────────┤
│ 56cd508b04ac9a53aa2cdf68536d6963 │      8 │
├──────────────────────────────────┼────────┤
│ e8ee65dcdaf504a45ef717e3c111ed7d │      6 │
├──────────────────────────────────┼────────┤
│ bc8b811845ceaf9b14c0721d97c30691 │      8 │
├──────────────────────────────────┼────────┤
│ 785702be8401728d942075fbe2372b72 │      8 │
├──────────────────────────────────┼────────┤
│ 56e812dac283d0df19bada604f155367 │      9 │
├──────────────────────────────────┼────────┤
│ 3240bf8a1bd85d20b9ce611947fe879b │      4 │
└──────────────────────────────────┴────────┘
insert new key and evict less used
DEBUG:__main__:evicting key 3240bf8a1bd85d20b9ce611947fe879b from cache
DEBUG:__main__:invalidating key 3240bf8a1bd85d20b9ce611947fe879b from cache
DEBUG:__main__:Object with hash 81051f331bd925ce4b1b7eaaf4364d49 added to cache
┌──────────────────────────────────┬────────┐
│ key                              │   Hits │
├──────────────────────────────────┼────────┤
│ 7557457053c85ce298cec0943ef005a9 │      6 │
├──────────────────────────────────┼────────┤
│ 5552c91d88f02d64fc5c505a5da99ef3 │      8 │
├──────────────────────────────────┼────────┤
│ 4facabbbb86de55456ab10a72e082a7a │     13 │
├──────────────────────────────────┼────────┤
│ 2ef1d6ba53f9d852668e0c46cd0d0b30 │      9 │
├──────────────────────────────────┼────────┤
│ 56cd508b04ac9a53aa2cdf68536d6963 │      8 │
├──────────────────────────────────┼────────┤
│ e8ee65dcdaf504a45ef717e3c111ed7d │      6 │
├──────────────────────────────────┼────────┤
│ bc8b811845ceaf9b14c0721d97c30691 │      8 │
├──────────────────────────────────┼────────┤
│ 785702be8401728d942075fbe2372b72 │      8 │
├──────────────────────────────────┼────────┤
│ 56e812dac283d0df19bada604f155367 │      9 │
├──────────────────────────────────┼────────┤
│ 81051f331bd925ce4b1b7eaaf4364d49 │      0 │
└──────────────────────────────────┴────────┘