More small changes from code inspection

[zxing.git] / core / src / com / google / zxing / ReaderException.java

diff --git a/core/src/com/google/zxing/ReaderException.java b/core/src/com/google/zxing/ReaderException.java
index cd6299c..0d8a3d5 100644 (file)
--- a/core/src/com/google/zxing/ReaderException.java
+++ b/core/src/com/google/zxing/ReaderException.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2007 Google Inc.
+ * Copyright 2007 ZXing authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,15 +21,34 @@ package com.google.zxing;
  * This includes, but is not limited to, failing checksums / error correction algorithms, being
  * unable to locate finder timing patterns, and so on.
  *
- * @author srowen@google.com (Sean Owen)
+ * @author Sean Owen
  */
 public final class ReaderException extends Exception {
 
-  public ReaderException() {
+  // TODO: Currently we throw up to 400 ReaderExceptions while scanning a single 240x240 image before
+  // rejecting it. This involves a lot of overhead and memory allocation, and affects both performance
+  // and latency on continuous scan clients. In the future, we should change all the decoders not to
+  // throw exceptions for routine events, like not finding a barcode on a given row. Instead, we
+  // should return error codes back to the callers, and simply delete this class. In the mean time, I
+  // have altered this class to be as lightweight as possible, by ignoring the exception string, and
+  // by disabling the generation of stack traces, which is especially time consuming. These are just
+  // temporary measures, pending the big cleanup.
+
+  private static final ReaderException instance = new ReaderException();
+
+  private ReaderException() {
+    // do nothing
+  }
+
+  public static ReaderException getInstance() {
+    return instance;
   }
 
-  public ReaderException(String message) {
-    super(message);
+  // Prevent stack traces from being taken
+  // srowen says: huh, my IDE is saying this is not an override. native methods can't be overridden?
+  // This, at least, does not hurt. Because we use a singleton pattern here, it doesn't matter anyhow.
+  public Throwable fillInStackTrace() {
+    return null;
   }
 
 }