Documentation
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Overview ¶
Package lrucache implements a small bounded LRU cache safe for concurrent use. It exists so the enricher's per-process memoization caches (album → release-MBID, artist → MBID, etc.) have a hard size ceiling instead of growing for the lifetime of the process.
The cache is keyed by `comparable` and stores any value type. Map capacity is pre-allocated at construction so the bulk-ingestion phase of a 50k-track scan doesn't trigger Go map bucket resizing mid-flight; the doubly-linked list grows naturally.
We don't pull in `hashicorp/golang-lru` because the dependency surface isn't worth ~120 LOC of generics. Reads on empty buckets short-circuit cheaply.
**Zero `interface{}` boxing on the hot path** (PR-F audit follow-up). The prior implementation used `container/list`, whose `Element.Value` is `any` — every Get/Set required a type assertion to `*entry[K, V]`, and every PushFront allocated a `list.Element` value-box. This package replaces that with a struct-based generic doubly-linked list. Public API is unchanged: `Get`/`Set`/`Has`/`Len`.
Index ¶
Constants ¶
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Variables ¶
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Functions ¶
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Types ¶
type Cache ¶
type Cache[K comparable, V any] struct { // contains filtered or unexported fields }
Cache is a bounded, mutex-protected LRU. Zero value is NOT usable — always construct via New. The internal doubly-linked list is circular-with-sentinel: `root.next` is the MRU element, `root.prev` is the LRU tail. This idiom eliminates per-method nil checks for "empty list" vs "single element" cases.
func New ¶
func New[K comparable, V any](capacity int) *Cache[K, V]
New returns a Cache with the given capacity. Capacity <= 0 is silently treated as 1 — a zero-cap cache would never store anything, which is almost certainly a configuration bug we'd rather surface as "very small" than "silently broken".
func (*Cache[K, V]) Get ¶
Get returns the cached value and true on hit; the zero value and false on miss. A hit moves the entry to the front (most-recently- used).
func (*Cache[K, V]) Has ¶
Has returns true if key is present, without promoting it to MRU. Useful for negative-cache checks where the caller doesn't want the lookup itself to keep the entry alive.
Source Files