From d9884a5cac8cc3008b4f348a895c49354d05d9ae Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Sat, 15 Dec 2018 11:15:48 +0000
Subject: [PATCH] Make use of metadata cache

---
 src/yggdrasil/admin.go    | 15 ++++++++++---
 src/yggdrasil/metadata.go | 45 ++++++++++++++++++++++++++++-----------
 2 files changed, 44 insertions(+), 16 deletions(-)

diff --git a/src/yggdrasil/admin.go b/src/yggdrasil/admin.go
index d78499e..2fba594 100644
--- a/src/yggdrasil/admin.go
+++ b/src/yggdrasil/admin.go
@@ -322,8 +322,12 @@ func (a *admin) init(c *Core, listenaddr string) {
 			return admin_info{}, err
 		}
 	})
-	a.addHandler("getMeta", []string{"box_pub_key", "coords"}, func(in admin_info) (admin_info, error) {
-		result, err := a.admin_getMeta(in["box_pub_key"].(string), in["coords"].(string))
+	a.addHandler("getMeta", []string{"box_pub_key", "coords", "[nocache]"}, func(in admin_info) (admin_info, error) {
+		var nocache bool
+		if in["nocache"] != nil {
+			nocache = in["nocache"].(string) == "true"
+		}
+		result, err := a.admin_getMeta(in["box_pub_key"].(string), in["coords"].(string), nocache)
 		if err == nil {
 			var m map[string]interface{}
 			if err = json.Unmarshal(result, &m); err == nil {
@@ -813,13 +817,18 @@ func (a *admin) admin_dhtPing(keyString, coordString, targetString string) (dhtR
 	return dhtRes{}, errors.New(fmt.Sprintf("DHT ping timeout: %s", keyString))
 }
 
-func (a *admin) admin_getMeta(keyString, coordString string) (metadataPayload, error) {
+func (a *admin) admin_getMeta(keyString, coordString string, nocache bool) (metadataPayload, error) {
 	var key boxPubKey
 	if keyBytes, err := hex.DecodeString(keyString); err != nil {
 		return metadataPayload{}, err
 	} else {
 		copy(key[:], keyBytes)
 	}
+	if !nocache {
+		if response, err := a.core.metadata.getCachedMetadata(key); err == nil {
+			return response, nil
+		}
+	}
 	var coords []byte
 	for _, cstr := range strings.Split(strings.Trim(coordString, "[]"), " ") {
 		if cstr == "" {
diff --git a/src/yggdrasil/metadata.go b/src/yggdrasil/metadata.go
index 19393b1..4acd467 100644
--- a/src/yggdrasil/metadata.go
+++ b/src/yggdrasil/metadata.go
@@ -1,6 +1,7 @@
 package yggdrasil
 
 import (
+	"errors"
 	"sync"
 	"time"
 )
@@ -11,36 +12,51 @@ type metadata struct {
 	myMetadataMutex sync.RWMutex
 	callbacks       map[boxPubKey]metadataCallback
 	callbacksMutex  sync.Mutex
-	cache           map[boxPubKey]metadataPayload
+	cache           map[boxPubKey]metadataCached
 	cacheMutex      sync.RWMutex
 }
 
 type metadataPayload []byte
 
+type metadataCached struct {
+	payload metadataPayload
+	created time.Time
+}
+
 type metadataCallback struct {
 	call    func(meta *metadataPayload)
 	created time.Time
 }
 
-// Initialises the metadata cache/callback stuff
+// Initialises the metadata cache/callback maps, and starts a goroutine to keep
+// the cache/callback maps clean of stale entries
 func (m *metadata) init(core *Core) {
 	m.core = core
 	m.callbacks = make(map[boxPubKey]metadataCallback)
-	m.cache = make(map[boxPubKey]metadataPayload)
+	m.cache = make(map[boxPubKey]metadataCached)
 
 	go func() {
 		for {
+			m.callbacksMutex.Lock()
 			for boxPubKey, callback := range m.callbacks {
 				if time.Since(callback.created) > time.Minute {
 					delete(m.callbacks, boxPubKey)
 				}
 			}
-			time.Sleep(time.Second * 5)
+			m.callbacksMutex.Unlock()
+			m.cacheMutex.Lock()
+			for boxPubKey, cache := range m.cache {
+				if time.Since(cache.created) > time.Hour {
+					delete(m.cache, boxPubKey)
+				}
+			}
+			m.cacheMutex.Unlock()
+			time.Sleep(time.Second * 30)
 		}
 	}()
 }
 
-// Add a callback
+// Add a callback for a metadata lookup
 func (m *metadata) addCallback(sender boxPubKey, call func(meta *metadataPayload)) {
 	m.callbacksMutex.Lock()
 	defer m.callbacksMutex.Unlock()
@@ -60,14 +76,14 @@ func (m *metadata) callback(sender boxPubKey, meta metadataPayload) {
 	}
 }
 
-// Get the metadata
+// Get the current node's metadata
 func (m *metadata) getMetadata() metadataPayload {
 	m.myMetadataMutex.RLock()
 	defer m.myMetadataMutex.RUnlock()
 	return m.myMetadata
 }
 
-// Set the metadata
+// Set the current node's metadata
 func (m *metadata) setMetadata(meta metadataPayload) {
 	m.myMetadataMutex.Lock()
 	defer m.myMetadataMutex.Unlock()
@@ -78,20 +94,23 @@ func (m *metadata) setMetadata(meta metadataPayload) {
 func (m *metadata) addCachedMetadata(key boxPubKey, payload metadataPayload) {
 	m.cacheMutex.Lock()
 	defer m.cacheMutex.Unlock()
-	m.cache[key] = payload
+	m.cache[key] = metadataCached{
+		created: time.Now(),
+		payload: payload,
+	}
 }
 
 // Get a metadata entry from the cache
-func (m *metadata) getCachedMetadata(key boxPubKey) metadataPayload {
+func (m *metadata) getCachedMetadata(key boxPubKey) (metadataPayload, error) {
 	m.cacheMutex.RLock()
 	defer m.cacheMutex.RUnlock()
 	if meta, ok := m.cache[key]; ok {
-		return meta
+		return meta.payload, nil
 	}
-	return metadataPayload{}
+	return metadataPayload{}, errors.New("No cache entry found")
 }
 
-// Handles a meta request/response.
+// Handles a meta request/response - called from the router
 func (m *metadata) handleMetadata(meta *sessionMeta) {
 	if meta.IsResponse {
 		m.callback(meta.SendPermPub, meta.Metadata)
@@ -101,7 +120,7 @@ func (m *metadata) handleMetadata(meta *sessionMeta) {
 	}
 }
 
-// Send metadata request or response
+// Send metadata request or response - called from the router
 func (m *metadata) sendMetadata(key boxPubKey, coords []byte, isResponse bool) {
 	table := m.core.switchTable.table.Load().(lookupTable)
 	meta := sessionMeta{