StackFrameStream.java revision 9883:903a2e023ffb 
1/*
2 * Copyright (c) 2000, 2004, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25package sun.jvm.hotspot.runtime;
26
27import sun.jvm.hotspot.utilities.*;
28
29/** <P> StackFrameStream iterates through the frames of a thread
30    starting from top most frame. It automatically takes care of
31    updating the location of all (callee-saved) registers. Notice: If
32    a thread is stopped at a safepoint, all registers are saved, not
33    only the callee-saved ones. </P>
34
35    <P> Use: </P>
36
37    <PRE>
38    for(StackFrameStream fst = new StackFrameStream(thread); !fst.isDone(); fst.next()) {
39      ...
40    }
41    </PRE>
42*/
43
44public class StackFrameStream {
45  private Frame       fr;
46  private RegisterMap regMap;
47  private boolean     isDone;
48
49  /** Equivalent to StackFrameStream(thread, true) */
50  public StackFrameStream(JavaThread thread) {
51    this(thread, true);
52  }
53
54  public StackFrameStream(JavaThread thread, boolean update) {
55    if (!VM.getVM().isDebugging()) {
56      if (Assert.ASSERTS_ENABLED) {
57        Assert.that(thread.hasLastJavaFrame(), "sanity check");
58      }
59      fr = thread.getLastFrame();
60      regMap = thread.newRegisterMap(update);
61      isDone = false;
62    } else {
63      // Special case code to find the topmost Java frame
64      // FIXME: should check to see whether we're at safepoint, and if
65      // so, skip the "current frame guess" call and unnecessary
66      // stackwalking work
67      fr = thread.getCurrentFrameGuess();
68      regMap = thread.newRegisterMap(update);
69      while ((fr != null) && (!fr.isJavaFrame())) {
70        if (fr.isFirstFrame()) {
71          fr = null;
72        } else {
73          fr = fr.sender(regMap);
74        }
75      }
76      if (fr == null) {
77        isDone = true;
78      }
79    }
80  }
81
82  /** Iteration */
83  public boolean isDone() {
84    if (isDone) {
85      return true;
86    } else {
87      if (fr == null) {
88        isDone = true;
89        return true;
90      }
91      isDone = fr.isFirstFrame();
92      return false;
93    }
94  }
95
96  public void next() {
97    if (!isDone) {
98      fr = fr.sender(regMap);
99    }
100  }
101
102  /** Query */
103  public Frame getCurrent()           { return fr;     }
104  public RegisterMap getRegisterMap() { return regMap; }
105}
106