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Addresses partially #77
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,100 @@ | ||
| // Package routecache is meant to assist in resolving the most used routes at | ||
| // an application. Implemented as a LRU, it returns always its full context for | ||
| // iteration at the router handler. | ||
| package routecache | ||
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| // based on groupcache's LRU | ||
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| import ( | ||
| "container/list" | ||
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| "github.com/iron-io/functions/api/models" | ||
| ) | ||
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| const defaultMaxEntries = 100 | ||
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| // Cache holds an internal linkedlist for hotness management. It is not safe | ||
| // for concurrent use, must be guarded externally. | ||
| type Cache struct { | ||
| maxentries int | ||
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| ll *list.List | ||
| cache map[*models.Route]*list.Element | ||
| values []*models.Route | ||
| } | ||
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| type routecacheentry struct { | ||
| route *models.Route | ||
| } | ||
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| // New returns a route cache. | ||
| func New() *Cache { | ||
| return &Cache{ | ||
| maxentries: defaultMaxEntries, | ||
| ll: list.New(), | ||
| cache: make(map[*models.Route]*list.Element), | ||
| } | ||
| } | ||
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| // Routes is an ordered slice with the hottest routes at the beginning, so to | ||
| // increase the likelihood of matching with incoming requests. | ||
| func (c *Cache) Routes() []*models.Route { | ||
| return c.values | ||
| } | ||
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| // Refresh updates internal linkedlist either adding a new route to the top, or | ||
| // moving it to the top when used. It will discard seldom used routes. | ||
| func (c *Cache) Refresh(route *models.Route) { | ||
| if c.cache == nil { | ||
| c.cache = make(map[*models.Route]*list.Element) | ||
| c.ll = list.New() | ||
| } | ||
| if ee, ok := c.cache[route]; ok { | ||
| c.ll.MoveToFront(ee) | ||
| ee.Value.(*routecacheentry).route = route | ||
| c.updatevalues() | ||
| return | ||
| } | ||
| ele := c.ll.PushFront(&routecacheentry{route}) | ||
| c.cache[route] = ele | ||
| if c.maxentries != 0 && c.ll.Len() > c.maxentries { | ||
| c.removeOldest() | ||
| return | ||
| } | ||
|
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| c.updatevalues() | ||
| } | ||
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| func (c *Cache) updatevalues() { | ||
| c.values = make([]*models.Route, 0, c.ll.Len()) | ||
| for e := c.ll.Front(); e != nil; e = e.Next() { | ||
| route := e.Value.(*routecacheentry).route | ||
| c.values = append(c.values, route) | ||
| } | ||
| } | ||
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| func (c *Cache) remove(key *models.Route) { | ||
| if c.cache == nil { | ||
| return | ||
| } | ||
| if ele, hit := c.cache[key]; hit { | ||
| c.removeElement(ele) | ||
| } | ||
| } | ||
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| func (c *Cache) removeOldest() { | ||
| if c.cache == nil { | ||
| return | ||
| } | ||
| ele := c.ll.Back() | ||
| if ele != nil { | ||
| c.removeElement(ele) | ||
| } | ||
| } | ||
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| func (c *Cache) removeElement(e *list.Element) { | ||
| c.ll.Remove(e) | ||
| kv := e.Value.(*routecacheentry) | ||
| delete(c.cache, kv.route) | ||
| c.updatevalues() | ||
| } |
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