--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/agent/src/share/classes/sun/jvm/hotspot/runtime/StackFrameStream.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,105 @@
+/*
+ * Copyright 2000-2004 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+package sun.jvm.hotspot.runtime;
+
+import sun.jvm.hotspot.utilities.*;
+
+/** <P> StackFrameStream iterates through the frames of a thread
+    starting from top most frame. It automatically takes care of
+    updating the location of all (callee-saved) registers. Notice: If
+    a thread is stopped at a safepoint, all registers are saved, not
+    only the callee-saved ones. </P>
+
+    <P> Use: </P>
+
+    <PRE>
+    for(StackFrameStream fst = new StackFrameStream(thread); !fst.isDone(); fst.next()) {
+      ...
+    }
+    </PRE>
+*/
+
+public class StackFrameStream {
+  private Frame       fr;
+  private RegisterMap regMap;
+  private boolean     isDone;
+
+  /** Equivalent to StackFrameStream(thread, true) */
+  public StackFrameStream(JavaThread thread) {
+    this(thread, true);
+  }
+
+  public StackFrameStream(JavaThread thread, boolean update) {
+    if (!VM.getVM().isDebugging()) {
+      if (Assert.ASSERTS_ENABLED) {
+        Assert.that(thread.hasLastJavaFrame(), "sanity check");
+      }
+      fr = thread.getLastFrame();
+      regMap = thread.newRegisterMap(update);
+      isDone = false;
+    } else {
+      // Special case code to find the topmost Java frame
+      // FIXME: should check to see whether we're at safepoint, and if
+      // so, skip the "current frame guess" call and unnecessary
+      // stackwalking work
+      fr = thread.getCurrentFrameGuess();
+      regMap = thread.newRegisterMap(update);
+      while ((fr != null) && (!fr.isJavaFrame())) {
+        if (fr.isFirstFrame()) {
+          fr = null;
+        } else {
+          fr = fr.sender(regMap);
+        }
+      }
+      if (fr == null) {
+        isDone = true;
+      }
+    }
+  }
+
+  /** Iteration */
+  public boolean isDone() {
+    if (isDone) {
+      return true;
+    } else {
+      if (fr == null) {
+        isDone = true;
+        return true;
+      }
+      isDone = fr.isFirstFrame();
+      return false;
+    }
+  }
+
+  public void next() {
+    if (!isDone) {
+      fr = fr.sender(regMap);
+    }
+  }
+
+  /** Query */
+  public Frame getCurrent()           { return fr;     }
+  public RegisterMap getRegisterMap() { return regMap; }
+}