<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div>[CC-ing mlvm-dev with my reply, since your note is of great general interest. -- John]</div><div><br></div><div>On Apr 22, 2008, at 11:22 AM, Lukas Stadler wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Hi!</div> <blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">If you have a login for that wiki, send me your login identifier, and I'll add you to the author list.<span class="Apple-converted-space"> </span>('ChristianWimmer' already has author access, and every JVM developer should have it, though I have to enter the names one at a time for now.)</div> </blockquote><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">I've created a wikis.sun.com user named "LukasStadler". It would be great if you could add that account to the author list.</div></blockquote><div><br></div><div>Done this morning... Please feel free to create or edit pages in HotSpotInternals, especially notes on implementation as you learn your way around.</div><div><br></div><blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Building: Maybe it should be mentioned that the mercurial mq extension needs to be enabled. It took me a while to figure out where the "qselect" command comes from...</div></blockquote><div><br></div><div>Thanks; I'll fix it in the README.</div><div><br></div><blockquote type="cite"><blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Are the continuations really bounded?<span class="Apple-converted-space"> </span>(Looks like the framework's main method, as reflected, serves as a boundary token.)<span class="Apple-converted-space"> </span>What happens when you try to return from a bounded continuation?</div> </blockquote><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Good question - right now it is silently assumed that the continuation is reinstated at a correct position (in this case the stackframes are removed up to and including the main method, and then the main method is the first stackframe to be installed again)</div></blockquote><div><br></div><div>I suppose when a continuation is resumed all frames up to its bound should be overwritten.</div><br><blockquote type="cite"> <blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">I thought there was some serialization story there.<span class="Apple-converted-space"> </span>The source code mentions a need to setAccessible(true).<span class="Apple-converted-space"> </span>(Another potential security challenge, out of many in this work.)</div> </blockquote><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Hm... I don't think that there's a way - Method doesn't implement Serializable and there's no special code in the ObjectOutputStream... But it's not that big a problem anyway, I just don't see why Class is serializable and Method is not.</div></blockquote><div><br></div><div>Here is a guess: There's a security hole if you allow arbitrary methods to be created from raw bytes with their "accessible" bit set to true. But the fix would be to do the same security checks that setAccessible does in the first place.</div><div><br></div><blockquote type="cite"> <blockquote type="cite"><blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-converted-space"> </span>- Sounds like a reorganization of the code may allow nearly complete reuse of the deopt blob</div> </blockquote><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">I hope so.<span class="Apple-converted-space"> </span>There are not that many degrees of freedom in interpreter frames, so it should not need fundamentally new techniques.</div> </blockquote><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">I added an entry point into the deopt_blob that can be passed an UnrollInfo object (and that doesn't call fetch_unroll_info). It's only ~10 new lines of code. One problem that I see is that it may be necessary to remove the stackframe of an inlined method from a compiled frame to reach the boundary method, which means that the topmost frame may need to be deoptimized. This might prove, uhm, interesting. (because it shouldn't return to the Interpreter after it's done)</div></blockquote><div><br></div>That's one reason I made the boundary method be a fixed native method doCopyStackContext. All those edge cases are easier to control that way. I don't see (yet) that it's a significant loss of generality.</div><div><br><blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><span class="Apple-style-span" style="-webkit-text-stroke-width: -1; ">I also added code to vframeArray and Deoptimization that creates a vframeArray from a StackSerializer. So far it works like a charm, although I'm ignoring monitors for now. (I don't really know how to create or acquire the BasicLock objects for monitors, ObjectSynchronizer::inflate?)</span></div></blockquote><div><br></div><div>I don't remember off hand, but I'd look at how the current deopt. or OSR code does the trick.</div><br><blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><span class="Apple-style-span" style="-webkit-text-stroke-width: -1; ">I have created Java classes for the stack state (see the attached files) and I've written native code that performs the stack copy operation into these objects. I'd like to work with this representation for the time being. I don't think that this is much less efficient than the StackSerializer (apart from the obviously larger memory consumption). Currently I'm writing code to create the vframeArray from this representation and I'll send you an overview of all the changes I made as soon as I'm finished with that.</span></div></blockquote><div>You probably need more random access than the serialized form can give you. Hmmm... The array-based representation is fine for prototyping but for production use is too transparent to optimize or secure. It's not a short term problem. What we need is a sort of union-type list abstraction that can equally easily store references and primitives (at least ints; would like IJFD), but without exposing its internals too much.</div><div><br></div><div><blockquote type="cite"><div><font class="Apple-style-span" face="'Courier New'">interface MachineWordList extends List<Object> {</font></div><div><font class="Apple-style-span" face="'Courier New'"> int size();</font></div><div><font class="Apple-style-span" face="'Courier New'"> byte type(int i);</font></div><div><font class="Apple-style-span" face="'Courier New'"> Object get(int i);</font></div><div><font class="Apple-style-span" face="'Courier New'"> int getInt(int i);</font></div><div><font class="Apple-style-span" face="'Courier New'"> long getLong(int i);</font></div><div><font class="Apple-style-span" face="'Courier New'"> // setters?</font></div><div><font class="Apple-style-span" face="'Courier New'"> void set(int i, Object x);</font></div><div><font class="Apple-style-span" face="'Courier New'"> void setInt(int i, int x);</font></div><div><font class="Apple-style-span" face="'Courier New'"> // arrays?</font></div><div><font class="Apple-style-span" face="'Courier New'"> byte[] typeArray();</font></div><div><font class="Apple-style-span" face="'Courier New'"> Object[] toArray();</font></div><div><font class="Apple-style-span" face="'Courier New'"> int[] toIntArray();</font></div><div><font class="Apple-style-span" face="'Courier New'">}</font></div></blockquote><div><br></div>But this is a cleanup; you don't have to turn aside from the main work.</div><div><br><blockquote type="cite"><br></blockquote></div><blockquote type="cite"> <blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Generators:<span class="Apple-converted-space"> </span>That's an important use case for "small scale" continuations.<span class="Apple-converted-space"> </span>Open question:<span class="Apple-converted-space"> </span>Does the existing design (a serialized blob of data) give enough visibility to the compiler to allow it to optimize across continuation invocations (thus inlining generator patterns)?<span class="Apple-converted-space"> </span>Probably not, unless the unsafe copyStack/resumeStack structures are made more stateless and immutable, so they can be examined by the compiler.</div> </blockquote><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">An ImmutableContinuation object, which allows no access to its contents whatsoever, would fit this purpose, I think. The compiler could even detect cases where the continuation is used as a nonlocal return in inlined methods and create no continuation at all...</div></blockquote>Yes, that's the end-to-end optimization that we want for things like generators.</div><div><br></div><div>Great work!</div><div><br></div><div>-- John</div><div><br></div><div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">package javax.stack;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">import java.lang.reflect.Method;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">/**</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "> * Contains the defining state of one stack frame activation. Read access provides access to private data, unverified</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "> * write access may allow code to escape security constraints, violate JVM invariants or even break the JVM.</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "> *</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "> * Data within this object is somewhat packed: the values and objects of local variables and expressions are</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "> * sequentially written into valueSlots and objectSlots. After that the monitors are written into objectSlots.</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "> */</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">public class Stackframe {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>private Method method;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>private int bci;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>private boolean[] localIsObject;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>private boolean[] expressionIsObject;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>private int[] valueSlots;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>private Object[] objectSlots;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public Method getMethod() {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>return method;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public void setMethod(Method method) {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>this.method = method;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public int getBci() {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>return bci;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public void setBci(int bci) {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>this.bci = bci;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public int getLocalCount() {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>return localIsObject == null ? 0 : localIsObject.length;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public int getExpressionCount() {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>return expressionIsObject == null ? 0 : expressionIsObject.length;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public int getMonitorCount() {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>return (valueSlots == null ? 0 : valueSlots.length) + (objectSlots == null ? 0 : objectSlots.length)</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>- getLocalCount() - getExpressionCount();</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public int getValueSlot(int index) {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>return valueSlots[index];</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public Object getObjectSlot(int index) {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>return objectSlots[index];</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public void setValueSlots(int[] valueSlots) {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>this.valueSlots = valueSlots;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public void setObjectSlots(Object[] objectSlots) {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>this.objectSlots = objectSlots;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public boolean localIsObject(int index) {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>return localIsObject[index];</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public boolean expressionIsObject(int index) {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>return expressionIsObject[index];</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public void setLocalIsObject(boolean[] localIsObject) {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>this.localIsObject = localIsObject;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public void setExpressionIsObject(boolean[] expressionIsObject) {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>this.expressionIsObject = expressionIsObject;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">package javax.stack;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">import java.lang.reflect.Method;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">/**</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "> * Allows to store stack frames so that they can be inspected, modified and reinstated. Any access beyond querying the</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "> * stack frame count and the methods poses a potential security risk.</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "> */</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">public class Continuation {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>private Stackframe[] stackframes;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public int getStackframeCount() {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>return stackframes == null ? 0 : stackframes.length;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public Method getMethod(int index) {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>return stackframes[index].getMethod();</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public Stackframe getStackframe(int index) {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>// TODO: security check ...</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>return stackframes[index];</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public Stackframe[] getStackframes() {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>// TODO: security check ...</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>return stackframes;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>public void setStackframes(Stackframe[] stackframes) {</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>// TODO: security check</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>this.stackframes = stackframes;</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">}</div></blockquote></div><div><br></div></div></body></html>