A handy class for tracking repeated calls to methods that should not be

called repeatedly.


git-svn-id: https://samskivert.googlecode.com/svn/trunk@1484 6335cc39-0255-0410-8fd6-9bcaacd3b74c

projects/samskivert/src/java/com/samskivert/util/RepeatCallTracker.java

@@ -0,0 +1,51 @@
+//
+// $Id$
+
+package com.samskivert.util;
+
+import com.samskivert.Log;
+
+/**
+ * A class used to debug situations where a method that should be called
+ * once and only once is being called again later and one wishes to report
+ * the stack trace of the first and current calling on any repeat
+ * callings. <em>Note:</em> this object is not thread safe. If the
+ * multiple callings may take place on different threads, you must
+ * synchronize the calls to {@link #checkCall} yourself.
+ */
+public class RepeatCallTracker
+{
+    /**
+     * This method should be called when the code passes through the code
+     * path that should be called only once. The first time through this
+     * path, the method will return false and record the stack trace.
+     * Subsquent calls will log an error and report the current and
+     * first-time-through stack traces.
+     *
+     * @param warning the warning message to issue prior to logging the
+     * two stack traces.
+     */
+    public boolean checkCall (String warning)
+    {
+        if (_firstCall == null) {
+            _firstCall = new Exception("---- First call ----");
+            _firstCall.fillInStackTrace();
+            return false;
+        }
+
+        Log.logStackTrace(new Exception(warning));
+        Log.logStackTrace(_firstCall);
+        return true;
+    }
+
+    /**
+     * Resets this repeat call tracker.
+     */
+    public void clear ()
+    {
+        _firstCall = null;
+    }
+
+    /** Used to keep the stack trace around from the first call. */
+    protected Exception _firstCall;
+}