Add 'ocis-pkg/' from commit '72d605ba3857d0b972ddd72e226d8a5360fb480d'

git-subtree-dir: ocis-pkg
git-subtree-mainline: 4c12bed11b
git-subtree-split: 72d605ba38

ocis-pkg/roles/cache.go

@@ -0,0 +1,71 @@
+package roles
+
+import (
+	"sync"
+	"time"
+
+	settings "github.com/owncloud/ocis-settings/pkg/proto/v0"
+)
+
+// entry extends a bundle and adds a TTL
+type entry struct {
+	*settings.Bundle
+	inserted time.Time
+}
+
+// cache is a cache implementation for roles, keyed by roleIDs.
+type cache struct {
+	entries map[string]entry
+	size    int
+	ttl     time.Duration
+	m       sync.Mutex
+}
+
+// newCache returns a new instance of Cache.
+func newCache(size int, ttl time.Duration) cache {
+	return cache{
+		size:    size,
+		ttl:     ttl,
+		entries: map[string]entry{},
+	}
+}
+
+// get gets a role-bundle by a given `roleID`.
+func (c *cache) get(roleID string) *settings.Bundle {
+	c.m.Lock()
+	defer c.m.Unlock()
+
+	if _, ok := c.entries[roleID]; ok {
+		return c.entries[roleID].Bundle
+	}
+	return nil
+}
+
+// set sets a roleID / role-bundle.
+func (c *cache) set(roleID string, value *settings.Bundle) {
+	c.m.Lock()
+	defer c.m.Unlock()
+
+	if !c.fits() {
+		c.evict()
+	}
+
+	c.entries[roleID] = entry{
+		value,
+		time.Now(),
+	}
+}
+
+// evict frees memory from the cache by removing entries that exceeded the cache TTL.
+func (c *cache) evict() {
+	for i := range c.entries {
+		if c.entries[i].inserted.Add(c.ttl).Before(time.Now()) {
+			delete(c.entries, i)
+		}
+	}
+}
+
+// fits returns whether the cache fits more entries.
+func (c *cache) fits() bool {
+	return c.size > len(c.entries)
+}