TUN-1350: Enhance error messages with cloudflarestatus.com link, if relevant

vendor/github.com/cloudflare/golibs/lrucache/cache.go

@@ -0,0 +1,69 @@
+// Copyright (c) 2013 CloudFlare, Inc.
+
+// Package lrucache implements a last recently used cache data structure.
+//
+// This code tries to avoid dynamic memory allocations - all required
+// memory is allocated on creation.  Access to the data structure is
+// O(1). Modification O(log(n)) if expiry is used, O(1)
+// otherwise.
+//
+// This package exports three things:
+//  LRUCache: is the main implementation. It supports multithreading by
+//      using guarding mutex lock.
+//
+//  MultiLRUCache: is a sharded implementation. It supports the same
+//      API as LRUCache and uses it internally, but is not limited to
+//      a single CPU as every shard is separately locked. Use this
+//      data structure instead of LRUCache if you have have lock
+//      contention issues.
+//
+//  Cache interface: Both implementations fulfill it.
+package lrucache
+
+import (
+	"time"
+)
+
+// Cache interface is fulfilled by the LRUCache and MultiLRUCache
+// implementations.
+type Cache interface {
+	// Methods not needing to know current time.
+	//
+	// Get a key from the cache, possibly stale. Update its LRU
+	// score.
+	Get(key string) (value interface{}, ok bool)
+	// Get a key from the cache, possibly stale. Don't modify its LRU score. O(1)
+	GetQuiet(key string) (value interface{}, ok bool)
+	// Get and remove a key from the cache.
+	Del(key string) (value interface{}, ok bool)
+	// Evict all items from the cache.
+	Clear() int
+	// Number of entries used in the LRU
+	Len() int
+	// Get the total capacity of the LRU
+	Capacity() int
+
+	// Methods use time.Now() when neccessary to determine expiry.
+	//
+	// Add an item to the cache overwriting existing one if it
+	// exists.
+	Set(key string, value interface{}, expire time.Time)
+	// Get a key from the cache, make sure it's not stale. Update
+	// its LRU score.
+	GetNotStale(key string) (value interface{}, ok bool)
+	// Evict all the expired items.
+	Expire() int
+
+	// Methods allowing to explicitly specify time used to
+	// determine if items are expired.
+	//
+	// Add an item to the cache overwriting existing one if it
+	// exists. Allows specifing current time required to expire an
+	// item when no more slots are used.
+	SetNow(key string, value interface{}, expire time.Time, now time.Time)
+	// Get a key from the cache, make sure it's not stale. Update
+	// its LRU score.
+	GetNotStaleNow(key string, now time.Time) (value interface{}, ok bool)
+	// Evict items that expire before Now.
+	ExpireNow(now time.Time) int
+}