Solution

common/consistenthash/consistenthash.go

@@ -18,9 +18,15 @@ type Ring struct {
 // search will find the index of the node that is responsible for the range that
 // includes the hashed value of key.
 func (r *Ring) search(key string) int {
-    /////////////////////////
-    // YOUR CODE GOES HERE //
-    /////////////////////////
+    keyHash := hashId(key)
+
+    // Assuming array is sorted after each insertion, get the node with the smallest
+    // hash that is bigger than the key hash
+    for index, node := range r.Nodes {
+        if (node.HashId > keyHash) {
+            return index
+        }
+    }
 
     return 0
 }

dynamo/cache.go

@@ -5,13 +5,10 @@ import (
     "sync"
 )
 
-///////////////////////////////
-// THIS FILE IS MISSING CODE //
-///////////////////////////////
-
 // Cache is the struct that handle all the data storage for the dynamo server.
 type Cache struct {
     data map[string]string
+    timestamps map[string]int64
     sync.Mutex
 }
 
@@ -20,6 +17,7 @@ func NewCache() *Cache {
     var s Cache
 
     s.data = make(map[string]string)
+    s.timestamps = make(map[string]int64)
 
     return &s
 }
@@ -29,7 +27,7 @@ func NewCache() *Cache {
 func (cache *Cache) Get(key string) (value string, timestamp int64) {
     cache.Lock()
     value = cache.data[key]
-    timestamp = 0
+    timestamp = cache.timestamps[key]
     cache.Unlock()
 
     log.Printf("[CACHE] Getting Key '%v' with Value '%v' @ timestamp '%v'\n", key, value, timestamp)
@@ -43,6 +41,7 @@ func (cache *Cache) Put(key string, value string, timestamp int64) {
 
     cache.Lock()
     cache.data[key] = value
+    cache.timestamps[key] = timestamp
     cache.Unlock()
 
     return
@@ -52,6 +51,6 @@ func (cache *Cache) Put(key string, value string, timestamp int64) {
 // except for testing purposes.
 func (cache *Cache) getAll() (data map[string]string, timestamps map[string]int64) {
     data = cache.data
-    timestamps = make(map[string]int64)
+    timestamps = cache.timestamps
     return data, timestamps
 }

dynamo/coordinator.go

@@ -186,13 +186,17 @@ func (server *Server) Voting(key string, quorum int) (string, error) {
 
 // aggregateVotes will select the right value from the votes received.
 func aggregateVotes(votes []*vote) (result string) {
+	var newestTimestamp int64
+	newestTimestamp = -1
+
 	for _, vote := range votes {
 		log.Printf("[COORDINATOR] Vote: %v\n", vote.value)
+		if (vote.timestamp > newestTimestamp) {
+			newestTimestamp = vote.timestamp
+			result = vote.value
+		}
 	}
 
-	/////////////////////////
-	// YOUR CODE GOES HERE //
-	/////////////////////////
-	result = votes[0].value
+	// Will return an empty string if the list is empty
 	return
 }