cleanup: Skip unused string concatenation (#43)

`updateEntity` in `LogisticsTileGenericPipe` currently creates a debug
string that goes unused in normal release builds. We can skip allocating
temporary `StringBuilder` instances by checking the DEBUG flag
directly.

Normally we'd use a format string with an additional varargs argument,
but the `add(Super)TraceInformation` methods already use a varargs
parameter to pass nested `Infos`. This is the pragmatic, cheap way to
remove the calls from the hot path.

(cherry picked from commit 23f83a5)

Author: szuend

src/main/java/logisticspipes/pipes/basic/LogisticsTileGenericPipe.java

@@ -165,8 +165,11 @@ public void onChunkUnload() {
 
     @Override
     public void updateEntity() {
-        Info superDebug = StackTraceUtil.addSuperTraceInformation("Time: " + getWorld().getWorldTime());
-        Info debug = StackTraceUtil.addTraceInformation("(" + getX() + ", " + getY() + ", " + getZ() + ")", superDebug);
+        Info debug = StackTraceUtil.DUMMY_INFO;
+        if (LPConstants.DEBUG) {
+            Info superDebug = StackTraceUtil.addSuperTraceInformation("Time: " + getWorld().getWorldTime());
+            debug = StackTraceUtil.addTraceInformation("(" + getX() + ", " + getY() + ", " + getZ() + ")", superDebug);
+        }
         if (sendInitPacket && MainProxy.isServer(getWorldObj())) {
             sendInitPacket = false;
             getRenderController().sendInit();

src/main/java/logisticspipes/utils/StackTraceUtil.java

@@ -18,7 +18,7 @@ public abstract static class Info {
         public abstract void end();
     }
 
-    private static final Info dummyInfo = new Info() {
+    public static final Info DUMMY_INFO = new Info() {
 
         @Override
         public void end() {}
@@ -30,7 +30,7 @@ private static LinkedList<Pair<StackTraceElement, String>> getList() {
 
     public static Info addTraceInformation(final String information, Info... infos) {
         if (!LPConstants.DEBUG) {
-            return dummyInfo;
+            return DUMMY_INFO;
         }
         StackTraceElement[] trace = Thread.currentThread().getStackTrace();
         final StackTraceElement calledFrom = trace[2];
@@ -39,7 +39,7 @@ public static Info addTraceInformation(final String information, Info... infos)
 
     public static Info addSuperTraceInformation(final String information, Info... infos) {
         if (!LPConstants.DEBUG) {
-            return dummyInfo;
+            return DUMMY_INFO;
         }
         StackTraceElement[] trace = Thread.currentThread().getStackTrace();
         final StackTraceElement calledFrom = trace[3];