89 lines
2 KiB
Go
89 lines
2 KiB
Go
package physical
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import (
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"strings"
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"github.com/hashicorp/golang-lru"
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log "github.com/mgutz/logxi/v1"
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)
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const (
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// DefaultCacheSize is used if no cache size is specified for NewCache
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DefaultCacheSize = 1024 * 1024
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)
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// Cache is used to wrap an underlying physical backend
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// and provide an LRU cache layer on top. Most of the reads done by
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// Vault are for policy objects so there is a large read reduction
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// by using a simple write-through cache.
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type Cache struct {
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backend Backend
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lru *lru.TwoQueueCache
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}
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// NewCache returns a physical cache of the given size.
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// If no size is provided, the default size is used.
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func NewCache(b Backend, size int, logger log.Logger) *Cache {
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if size <= 0 {
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size = DefaultCacheSize
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}
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if logger.IsTrace() {
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logger.Trace("physical/cache: creating LRU cache", "size", size)
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}
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cache, _ := lru.New2Q(size)
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c := &Cache{
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backend: b,
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lru: cache,
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}
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return c
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}
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// Purge is used to clear the cache
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func (c *Cache) Purge() {
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c.lru.Purge()
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}
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func (c *Cache) Put(entry *Entry) error {
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err := c.backend.Put(entry)
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c.lru.Add(entry.Key, entry)
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return err
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}
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func (c *Cache) Get(key string) (*Entry, error) {
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// Check the LRU first
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if raw, ok := c.lru.Get(key); ok {
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if raw == nil {
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return nil, nil
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} else {
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return raw.(*Entry), nil
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}
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}
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// Read from the underlying backend
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ent, err := c.backend.Get(key)
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if err != nil {
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return nil, err
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}
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// Cache the result. We do NOT cache negative results
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// for keys in the 'core/' prefix otherwise we risk certain
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// race conditions upstream. The primary issue is with the HA mode,
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// we could potentially negatively cache the leader entry and cause
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// leader discovery to fail.
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if ent != nil || !strings.HasPrefix(key, "core/") {
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c.lru.Add(key, ent)
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}
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return ent, err
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}
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func (c *Cache) Delete(key string) error {
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err := c.backend.Delete(key)
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c.lru.Remove(key)
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return err
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}
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func (c *Cache) List(prefix string) ([]string, error) {
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// Always pass-through as this would be difficult to cache.
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return c.backend.List(prefix)
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}
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