// Begins stack walking.
//
// Parameters:
// stackStream StackStream object
// mode Stack walking mode.
// skip_frames Number of frames to be skipped.
// frame_count Number of frames to be traversed.
// start_index Start index to the user-supplied buffers.
// frames_array Buffer to store StackFrame in, starting at start_index.
// frames array is a Class<?>[] array when only getting caller
// reference, and a StackFrameInfo[] array (or derivative)
// otherwise. It should never be null.
//
// Returns Object returned from AbstractStackWalker::doStackWalk call.
//
oop StackWalk::walk(Handle stackStream, jlong mode,
int skip_frames, int frame_count, int start_index,
objArrayHandle frames_array,
TRAPS) {
ResourceMark rm(THREAD);
JavaThread* jt = (JavaThread*)THREAD;
log_debug(stackwalk)("Start walking: mode " JLONG_FORMAT " skip %d frames batch size %d",
mode, skip_frames, frame_count);
if (frames_array.is_null()) {
THROW_MSG_(vmSymbols::java_lang_NullPointerException(), "frames_array is NULL", NULL);
}
// Setup traversal onto my stack.
if (live_frame_info(mode)) {
assert (use_frames_array(mode), "Bad mode for get live frame");
RegisterMap regMap(jt, true);
LiveFrameStream stream(jt, ®Map);
return fetchFirstBatch(stream, stackStream, mode, skip_frames, frame_count,
start_index, frames_array, THREAD);
} else {
JavaFrameStream stream(jt, mode);
return fetchFirstBatch(stream, stackStream, mode, skip_frames, frame_count,
start_index, frames_array, THREAD);
}
}
// Unpacks one or more frames into user-supplied buffers.
// Updates the end index, and returns the number of unpacked frames.
// Always start with the existing vfst.method and bci.
// Do not call vfst.next to advance over the last returned value.
// In other words, do not leave any stale data in the vfst.
//
// Parameters:
// mode Restrict which frames to be decoded.
// JavaFrameStream stream of javaVFrames
// max_nframes Maximum number of frames to be filled.
// start_index Start index to the user-supplied buffers.
// frames_array Buffer to store Class or StackFrame in, starting at start_index.
// frames array is a Class<?>[] array when only getting caller
// reference, and a StackFrameInfo[] array (or derivative)
// otherwise. It should never be null.
// end_index End index to the user-supplied buffers with unpacked frames.
//
// Returns the number of frames whose information was transferred into the buffers.
//
int StackWalk::fill_in_frames(jlong mode, JavaFrameStream& stream,
int max_nframes, int start_index,
objArrayHandle frames_array,
int& end_index, TRAPS) {
if (TraceStackWalk) {
tty->print_cr("fill_in_frames limit=%d start=%d frames length=%d",
max_nframes, start_index, frames_array->length());
}
assert(max_nframes > 0, "invalid max_nframes");
assert(start_index + max_nframes <= frames_array->length(), "oob");
int frames_decoded = 0;
for (; !stream.at_end(); stream.next()) {
Method* method = stream.method();
int bci = stream.bci();
if (method == NULL) continue;
if (!ShowHiddenFrames && StackWalk::skip_hidden_frames(mode)) {
if (method->is_hidden()) {
if (TraceStackWalk) {
tty->print(" hidden method: "); method->print_short_name();
tty->print("\n");
}
continue;
}
}
int index = end_index++;
if (TraceStackWalk) {
tty->print(" %d: frame method: ", index); method->print_short_name();
tty->print_cr(" bci=%d", bci);
}
// fill in StackFrameInfo and initialize MemberName
if (live_frame_info(mode)) {
assert (use_frames_array(mode), "Bad mode for get live frame");
Handle stackFrame(frames_array->obj_at(index));
fill_live_stackframe(stackFrame, method, bci, stream.java_frame(), CHECK_0);
} else if (need_method_info(mode)) {
assert (use_frames_array(mode), "Bad mode for get stack frame");
Handle stackFrame(frames_array->obj_at(index));
fill_stackframe(stackFrame, method, bci);
} else {
assert (use_frames_array(mode) == false, "Bad mode for get caller class");
frames_array->obj_at_put(index, method->method_holder()->java_mirror());
}
if (++frames_decoded >= max_nframes) break;
}
return frames_decoded;
}
// Walk the next batch of stack frames
//
// Parameters:
// stackStream StackStream object
// mode Stack walking mode.
// magic Must be valid value to continue the stack walk
// frame_count Number of frames to be decoded.
// start_index Start index to the user-supplied buffers.
// classes_array Buffer to store classes in, starting at start_index.
// frames_array Buffer to store StackFrame in, starting at start_index.
// NULL if not used.
//
// Returns the end index of frame filled in the buffer.
//
jint StackWalk::moreFrames(Handle stackStream, jlong mode, jlong magic,
int frame_count, int start_index,
objArrayHandle classes_array,
objArrayHandle frames_array,
TRAPS)
{
JavaThread* jt = (JavaThread*)THREAD;
StackWalkAnchor* existing_anchor = StackWalkAnchor::from_current(jt, magic, classes_array);
if (existing_anchor == NULL) {
THROW_MSG_(vmSymbols::java_lang_InternalError(), "doStackWalk: corrupted buffers", 0L);
}
if ((need_method_info(mode) || live_frame_info(mode)) && frames_array.is_null()) {
THROW_MSG_(vmSymbols::java_lang_NullPointerException(), "frames_array is NULL", 0L);
}
if (TraceStackWalk) {
tty->print_cr("StackWalk::moreFrames frame_count %d existing_anchor " PTR_FORMAT " start %d frames %d",
frame_count, p2i(existing_anchor), start_index, classes_array->length());
}
int end_index = start_index;
if (frame_count <= 0) {
return end_index; // No operation.
}
int count = frame_count + start_index;
assert (classes_array->length() >= count, "not enough space in buffers");
StackWalkAnchor& anchor = (*existing_anchor);
vframeStream& vfst = anchor.vframe_stream();
if (!vfst.at_end()) {
vfst.next(); // this was the last frame decoded in the previous batch
if (!vfst.at_end()) {
int n = fill_in_frames(mode, vfst, frame_count, start_index, classes_array,
frames_array, end_index, CHECK_0);
if (n < 1) {
THROW_MSG_(vmSymbols::java_lang_InternalError(), "doStackWalk: later decode failed", 0L);
}
return end_index;
}
}
return end_index;
}