remark42/backend/vendor/github.com/go-pkgz/rest/cache

Cache wrapper for web applications.

The primary goal is to simplify caching of responses.

Adds guava-style loading cache and support of scopes for partial flushes. Provides in-memory NewMemoryCache on top of hashicorp/golang-lru and defines basic interface for other implementations.

In addition to Get and Flush methods, memory cache also support limits for a single value size, number of keys and total memory utilization. PostFlushFn adds ability to call a function on flush completion.

Install and update

go get -u github.com/go-pkgz/rest/cache

Technical details

• Cache keeps data in a simple key:value format.
• Key is a type, created with Key(site_id) where site_id represents independent bucket in the cache. For simple cases can be set to an empty string.
• Particular key set by Key.ID(string)
• Key may contain optional scopes (list of string). They not affect retrieval and used for partial (scoped) invalidation only.
• Cache is safe for concurrent use.
• Value is []byte.
• Get method returns from the cache if the key already in. Overwise executes passed function and saves results.
• Special fake implementation cache.Nop satisfies LoadingCache interface and can be used to disable any caching

Usage

    // create in-memory cache with max keys=50, total (max) size=2000 and max cached size of a record = 200
    lc, err := cache.NewMemoryCache(cache.MaxKeys(50), cacheMaxCacheSize(2000), cache.MaxValSize(200)) 
    if err != nil {
        panic(err)
    }
    ...

    // load cached value for key1. Call func if not cached yet or evicted
    res, err = lc.Get(cache.NewKey("site1").ID("key1").Scopes("scope1"), func() ([]byte, error) {
		return []byte("1234567890"), nil
    }) 
    
    lc.Flush(cache.Flusher("site1").Scopes("scope1")) // invalidate cache for scope1