[REEF-791] Replace inefficient use of keySet iterator with entrySet iterator

• Type: Improvement
• Status: Resolved
• Priority: Trivial
• Resolution: Fixed
• Affects Version/s: 0.12
• Fix Version/s: 0.13
• Labels: easyfix
• Assignee: Dongjoon Hyun
• Reporter: Dongjoon Hyun
• Created: 29/Sep/15 19:20
• Updated: 29/Sep/15 20:09
• Resolved: 29/Sep/15 20:09

Description

We can improve performance by replacing `keySet` with `entrySet`. For example, see the following code pattern change in REEF-Wake.

-    for (final Class<? extends T> clazz : clazzToCodecMap.keySet()) {
-      clazzToEncoderMap.put(clazz, clazzToCodecMap.get(clazz));
-      clazzToDecoderMap.put(clazz, clazzToCodecMap.get(clazz));
+    for (final Entry<Class<? extends T>, Codec<? extends T>> e : clazzToCodecMap.entrySet()) {
+      clazzToEncoderMap.put(e.getKey(), e.getValue());
+      clazzToDecoderMap.put(e.getKey(), e.getValue());

As of today, we can find 6 candidates.

• CodecRamMap.java (reef-io)
• CommandLine.java (reef-tang)
• InjectorImpl.java (reef-tang)
• Tint.java (reef-tang)
• CacheImpl.java (reef-util)
• MultiCodec.java (reef-wake)

We can improve all except `InjectorImpl.java' using `TracingMonotonicTreeMap.java' that doesn't support `entrySet`.

Issue Links

• links to: Link to PR