2007-01-29 Kyle Galloway <kgallowa@redhat.com>

	* include/java-interp.h:  Added _Jv_Frame class and its two
	subclasses _Jv_InterpFrame and _Jv_NativeFrame.  Also moved
	_Jv_FrameType from java-stack.h.
	* include/java-stack.h: Removed _Jv_FrameType.
	* java/lang/Thread.java: Added frame member to hold new
	composite frame stack.
	* java/lang/Thread.h: Regenerated.
	* java/lang/Thread.class: Rebuilt.
	* jni.cc (_Jv_JNIMethod::call): Push a frame onto the stack when
	calling a JNI method.
	* jvmti.cc (_Jv_JVMTI_GetStackTrace): New Method.
	(_Jv_JVMTI_GetFrameCount): New method.
	* stacktrace.cc (UnwindTraceFn): Modified to use new _Jv_Frame
	classes.
	* testsuite/libjava.jvmti/interp/getstacktrace.jar: New test.
	* testsuite/libjava.jvmti/interp/natgetstacktrace.cc: New test.
	* testsuite/libjava.jvmti/interp/getstacktrace.h: New test.
	* testsuite/libjava.jvmti/interp/getstacktrace.jar: New test.
	* testsuite/libjava.jvmti/interp/getstacktrace.out: Output file
	for test. 

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@121314 138bc75d-0d04-0410-961f-82ee72b054a4

15 files changed, 537 insertions, 27 deletions

diff --git a/libjava/ChangeLog b/libjava/ChangeLog
index 20e91fdb1fd..037b1bb650d 100644
--- a/libjava/ChangeLog
+++ b/libjava/ChangeLog
@@ -1,3 +1,26 @@
+2007-01-29  Kyle Galloway  <kgallowa@redhat.com>
+
+	* include/java-interp.h:  Added _Jv_Frame class and its two
+	subclasses _Jv_InterpFrame and _Jv_NativeFrame.  Also moved
+	_Jv_FrameType from java-stack.h.
+	* include/java-stack.h: Removed _Jv_FrameType.
+	* java/lang/Thread.java: Added frame member to hold new
+	composite frame stack.
+	* java/lang/Thread.h: Regenerated.
+	* java/lang/Thread.class: Rebuilt.
+	* jni.cc (_Jv_JNIMethod::call): Push a frame onto the stack when
+	calling a JNI method.
+	* jvmti.cc (_Jv_JVMTI_GetStackTrace): New Method.
+	(_Jv_JVMTI_GetFrameCount): New method.
+	* stacktrace.cc (UnwindTraceFn): Modified to use new _Jv_Frame
+	classes.
+	* testsuite/libjava.jvmti/interp/getstacktrace.jar: New test.
+	* testsuite/libjava.jvmti/interp/natgetstacktrace.cc: New test.
+	* testsuite/libjava.jvmti/interp/getstacktrace.h: New test.
+	* testsuite/libjava.jvmti/interp/getstacktrace.jar: New test.
+	* testsuite/libjava.jvmti/interp/getstacktrace.out: Output file
+	for test. 
+
 2007-01-29  Tom Tromey  <tromey@redhat.com>
 
 	* interpret.cc (run_debug): Remove comment.
diff --git a/libjava/classpath/lib/java/lang/Thread$State.class b/libjava/classpath/lib/java/lang/Thread$State.class
index a7d5a333f22..3ce018edd9c 100644
--- a/libjava/classpath/lib/java/lang/Thread$State.class
+++ b/libjava/classpath/lib/java/lang/Thread$State.class
diff --git a/libjava/classpath/lib/java/lang/Thread.class b/libjava/classpath/lib/java/lang/Thread.class
index 7c33d004474..8329bc15523 100644
--- a/libjava/classpath/lib/java/lang/Thread.class
+++ b/libjava/classpath/lib/java/lang/Thread.class
diff --git a/libjava/include/java-interp.h b/libjava/include/java-interp.h
index 3b15b5cb222..3a43977747f 100644
--- a/libjava/include/java-interp.h
+++ b/libjava/include/java-interp.h
@@ -205,11 +205,11 @@ class _Jv_InterpMethod : public _Jv_MethodBase
   // number info is unavailable.
   int get_source_line(pc_t mpc);
 
+   public:
+
   // Convenience function for indexing bytecode PC/insn slots in
   // line tables for JDWP
   jlong insn_index (pc_t pc);
-  
-   public:
    
   /* Get the line table for this method.
    * start  is the lowest index in the method
@@ -315,35 +315,86 @@ public:
   }
 };
 
-// The interpreted call stack, represented by a linked list of frames.
-struct _Jv_InterpFrame
+enum _Jv_FrameType
 {
+  frame_native,
+  frame_interpreter,
+  frame_proxy
+};
+
+//  The composite call stack as represented by a linked list of frames
+class _Jv_Frame
+{
+public:
+  java::lang::Thread *thread;
+
   union
   {
+    _Jv_MethodBase *self;
     void *meth;
-    _Jv_InterpMethod *self;
     _Jv_Method *proxyMethod;
   };
-  java::lang::Thread *thread;
-  _Jv_InterpFrame *next;
+  
+  //The full list of frames, JNI and interpreted
+  _Jv_Frame *next;
+  _Jv_FrameType frame_type;
+  
+  _Jv_Frame (_Jv_MethodBase *s, java::lang::Thread *thr, _Jv_FrameType type)
+  {
+    self = s;
+    frame_type = type;
+    next = (_Jv_Frame *) thr->frame;
+    thr->frame = (gnu::gcj::RawData *) this;
+    thread = thr;
+  }
+
+  ~_Jv_Frame ()
+  {
+    thread->frame = (gnu::gcj::RawData *) next;
+  }
+};
+
+// An interpreted frame in the call stack
+class _Jv_InterpFrame : public _Jv_Frame
+{
+public:
+  
+  // Keep the purely interpreted list around so as not to break backtraces
+  _Jv_InterpFrame *next_interp;
+  
   union
   {
     pc_t pc;
     jclass proxyClass;
   };
-  
-  _Jv_InterpFrame (void *meth, java::lang::Thread *thr, jclass proxyClass = NULL)
+
+  //Debug info for local variables.
+  _Jv_word *locals;
+  char *locals_type;
+
+  _Jv_InterpFrame (void *meth, java::lang::Thread *thr, jclass proxyCls = NULL)
+  : _Jv_Frame (reinterpret_cast<_Jv_MethodBase *> (meth), thr,
+	             frame_interpreter)
   {
-    this->meth = meth;
-    thread = thr;
-    next = (_Jv_InterpFrame *) thr->interp_frame;
+    next_interp = (_Jv_InterpFrame *) thr->interp_frame;
+    proxyClass = proxyCls;
     thr->interp_frame = (gnu::gcj::RawData *) this;
-    this->proxyClass = proxyClass;
   }
 
   ~_Jv_InterpFrame ()
   {
-    thread->interp_frame = (gnu::gcj::RawData *) next;
+    thread->interp_frame = (gnu::gcj::RawData *) next_interp;
+  }
+};
+
+// A native frame in the call stack really just a placeholder
+class _Jv_NativeFrame : public _Jv_Frame
+{
+public:
+
+  _Jv_NativeFrame (_Jv_JNIMethod *s, java::lang::Thread *thr)
+  : _Jv_Frame (s, thr, frame_native)
+  {
   }
 };
 
diff --git a/libjava/include/java-stack.h b/libjava/include/java-stack.h
index d4d63d74342..49e68412be6 100644
--- a/libjava/include/java-stack.h
+++ b/libjava/include/java-stack.h
@@ -41,13 +41,6 @@ extern "Java"
   }
 }
 
-enum _Jv_FrameType
-{
-  frame_native,
-  frame_interpreter,
-  frame_proxy
-};
-
 #ifdef INTERPRETER
 struct _Jv_InterpFrameInfo
 {
diff --git a/libjava/java/lang/Thread.h b/libjava/java/lang/Thread.h
index 74e149030f7..d5fce863877 100644
--- a/libjava/java/lang/Thread.h
+++ b/libjava/java/lang/Thread.h
@@ -144,7 +144,8 @@ public: // actually package-private
   static const jbyte THREAD_PARK_DEAD = 3;
   ::java::lang::Object * accessControlState;
   ::gnu::gcj::RawData * interp_frame;
-  jint volatile state;
+  ::gnu::gcj::RawData * frame;
+  volatile jint state;
   ::gnu::gcj::RawDataManaged * data;
 public:
   static ::java::lang::Class class$;
diff --git a/libjava/java/lang/Thread.java b/libjava/java/lang/Thread.java
index 9666482040a..7216512530d 100644
--- a/libjava/java/lang/Thread.java
+++ b/libjava/java/lang/Thread.java
@@ -182,6 +182,9 @@ public class Thread implements Runnable
   
   // This describes the top-most interpreter frame for this thread.
   RawData interp_frame;
+  
+  // This describes the top most frame in the composite (interp + JNI) stack
+  RawData frame;
 
   // Current state.
   volatile int state;
diff --git a/libjava/jni.cc b/libjava/jni.cc
index 59c1e5fd03e..07ef7134540 100644
--- a/libjava/jni.cc
+++ b/libjava/jni.cc
@@ -2339,6 +2339,10 @@ _Jv_JNIMethod::call (ffi_cif *, void *ret, ffi_raw *args, void *__this)
 
   // Copy over passed-in arguments.
   memcpy (&real_args[offset], args, _this->args_raw_size);
+  
+  // Add a frame to the composite (interpreted + JNI) call stack
+  java::lang::Thread *thread = java::lang::Thread::currentThread();
+  _Jv_NativeFrame nat_frame (_this, thread);
 
   // The actual call to the JNI function.
 #if FFI_NATIVE_RAW_API
diff --git a/libjava/jvmti.cc b/libjava/jvmti.cc
index 03eec74b4c1..c9c7e7ba731 100644
--- a/libjava/jvmti.cc
+++ b/libjava/jvmti.cc
@@ -237,6 +237,34 @@ _Jv_JVMTI_GetAllThreads(MAYBE_UNUSED jvmtiEnv *env, jint *thread_cnt,
 }
 
 static jvmtiError JNICALL
+_Jv_JVMTI_GetFrameCount (MAYBE_UNUSED jvmtiEnv *env, jthread thread,
+                         jint* frame_count)
+{
+  REQUIRE_PHASE (env, JVMTI_PHASE_LIVE);
+  
+  NULL_CHECK (frame_count);
+	
+  using namespace java::lang;
+  
+  THREAD_DEFAULT_TO_CURRENT (thread);
+  
+  Thread *thr = reinterpret_cast<Thread *> (thread);
+  THREAD_CHECK_VALID (thr);
+  THREAD_CHECK_IS_ALIVE (thr);
+   
+  _Jv_Frame *frame = reinterpret_cast<_Jv_Frame *> (thr->frame);
+  (*frame_count) = 0;
+  
+  while (frame != NULL)
+    {
+      (*frame_count)++;
+      frame = frame->next;
+    }
+  
+  return JVMTI_ERROR_NONE;
+}
+
+static jvmtiError JNICALL
 _Jv_JVMTI_CreateRawMonitor (MAYBE_UNUSED jvmtiEnv *env, const char *name,
 			    jrawMonitorID *result)
 {
@@ -748,6 +776,82 @@ _Jv_JVMTI_GetClassLoaderClasses (MAYBE_UNUSED jvmtiEnv *env,
 }
 
 static jvmtiError JNICALL
+_Jv_JVMTI_GetStackTrace (MAYBE_UNUSED jvmtiEnv *env, jthread thread,
+                         jint start_depth, jint max_frames,
+                         jvmtiFrameInfo *frames, jint *frame_count)
+{
+  REQUIRE_PHASE (env, JVMTI_PHASE_LIVE);
+
+  ILLEGAL_ARGUMENT (max_frames < 0);
+  
+  NULL_CHECK (frames);
+  NULL_CHECK (frame_count);
+	
+  using namespace java::lang;
+  
+  THREAD_DEFAULT_TO_CURRENT (thread);
+  
+  Thread *thr = reinterpret_cast<Thread *> (thread);
+  THREAD_CHECK_VALID (thr);
+  THREAD_CHECK_IS_ALIVE (thr);
+    
+  jvmtiError jerr = env->GetFrameCount (thread, frame_count);
+  if (jerr != JVMTI_ERROR_NONE)
+    return jerr;
+  
+  // start_depth can be either a positive number, indicating the depth of the
+  // stack at which to begin the trace, or a negative number indicating the
+  // number of frames at the bottom of the stack to exclude.  These checks
+  // ensure that it is a valid value in either case
+  
+  ILLEGAL_ARGUMENT (start_depth >= (*frame_count));
+  ILLEGAL_ARGUMENT (start_depth < (-(*frame_count)));
+  
+  _Jv_Frame *frame = reinterpret_cast<_Jv_Frame *> (thr->frame);
+
+  // If start_depth is negative use this to determine at what depth to start
+  // the trace by adding it to the length of the call stack.  This allows the
+  // use of the same frame "discarding" mechanism as for a positive start_depth
+  if (start_depth < 0)
+    start_depth = *frame_count + start_depth;
+  
+  // If start_depth > 0 "remove" start_depth frames from the beginning
+  // of the stack before beginning the trace by moving along the frame list.
+  while (start_depth > 0)
+    {
+      frame = frame->next;
+      start_depth--;
+      (*frame_count)--;
+    }
+  
+  // Now check to see if the array supplied by the agent is large enough to
+  // hold frame_count frames, after adjustment for start_depth.
+  if ((*frame_count) > max_frames)
+    (*frame_count) = max_frames;
+  
+  for (int i = 0; i < (*frame_count); i++)
+    {
+      frames[i].method = frame->self->get_method ();
+      
+      // Set the location in the frame, native frames have location = -1
+      if (frame->frame_type == frame_interpreter)
+        {
+          _Jv_InterpMethod *imeth 
+            = static_cast<_Jv_InterpMethod *> (frame->self);
+          _Jv_InterpFrame *interp_frame 
+            = static_cast<_Jv_InterpFrame *> (frame);
+          frames[i].location = imeth->insn_index (interp_frame->pc);
+        }
+      else
+        frames[i].location = -1;
+        
+      frame = frame->next;
+    }
+    
+  return JVMTI_ERROR_NONE;
+}
+
+static jvmtiError JNICALL
 _Jv_JVMTI_ForceGarbageCollection (MAYBE_UNUSED jvmtiEnv *env)
 {
   REQUIRE_PHASE (env, JVMTI_PHASE_LIVE);
@@ -1484,7 +1588,7 @@ struct _Jv_jvmtiEnv _Jv_JVMTI_Interface =
   UNIMPLEMENTED,		// GetTopThreadGroups
   UNIMPLEMENTED,		// GetThreadGroupInfo
   UNIMPLEMENTED,		// GetThreadGroupChildren
-  UNIMPLEMENTED,		// GetFrameCount
+  _Jv_JVMTI_GetFrameCount,		// GetFrameCount
   UNIMPLEMENTED,		// GetThreadState
   RESERVED,			// reserved18
   UNIMPLEMENTED,		// GetFrameLocation
@@ -1572,7 +1676,7 @@ struct _Jv_jvmtiEnv _Jv_JVMTI_Interface =
   UNIMPLEMENTED,		// GetThreadListStackTraces
   UNIMPLEMENTED,		// GetThreadLocalStorage
   UNIMPLEMENTED,		// SetThreadLocalStorage
-  UNIMPLEMENTED,		// GetStackTrace
+  _Jv_JVMTI_GetStackTrace,		// GetStackTrace
   RESERVED,			// reserved105
   UNIMPLEMENTED,		// GetTag
   UNIMPLEMENTED,		// SetTag
diff --git a/libjava/stacktrace.cc b/libjava/stacktrace.cc
index 5751e29b5f1..c3fbdf4e6a4 100644
--- a/libjava/stacktrace.cc
+++ b/libjava/stacktrace.cc
@@ -131,9 +131,11 @@ _Jv_StackTrace::UnwindTraceFn (struct _Unwind_Context *context, void *state_ptr)
   if (func_addr == UNWRAP_FUNCTION_DESCRIPTOR (interp_run))
     {
       state->frames[pos].type = frame_interpreter;
-      state->frames[pos].interp.meth = state->interp_frame->self;
+      _Jv_Frame *frame = static_cast<_Jv_Frame *> (state->interp_frame);
+      state->frames[pos].interp.meth 
+        = static_cast<_Jv_InterpMethod *> (frame->self);
       state->frames[pos].interp.pc = state->interp_frame->pc;
-      state->interp_frame = state->interp_frame->next;
+      state->interp_frame = state->interp_frame->next_interp;
     }
   else 
 #endif
@@ -143,7 +145,7 @@ _Jv_StackTrace::UnwindTraceFn (struct _Unwind_Context *context, void *state_ptr)
       state->frames[pos].type = frame_proxy;
       state->frames[pos].proxyClass = state->interp_frame->proxyClass;
       state->frames[pos].proxyMethod = state->interp_frame->proxyMethod;
-      state->interp_frame = state->interp_frame->next;
+      state->interp_frame = state->interp_frame->next_interp;
     }
   else 
     {
diff --git a/libjava/testsuite/libjava.jvmti/interp/getstacktrace.h b/libjava/testsuite/libjava.jvmti/interp/getstacktrace.h
new file mode 100644
index 00000000000..6e5e8774e25
--- /dev/null
+++ b/libjava/testsuite/libjava.jvmti/interp/getstacktrace.h
@@ -0,0 +1,21 @@
+/* DO NOT EDIT THIS FILE - it is machine generated */
+
+#ifndef __getstacktrace__
+#define __getstacktrace__
+
+#include <jni.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+JNIEXPORT void JNICALL Java_getstacktrace_natPlaceholder (JNIEnv *env, jobject);
+JNIEXPORT void JNICALL Java_getstacktrace_natRunner (JNIEnv *env, jobject);
+JNIEXPORT jint JNICALL Java_getstacktrace_do_1getstacktrace_1tests (JNIEnv *env, jclass, jobjectArray);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __getstacktrace__ */
diff --git a/libjava/testsuite/libjava.jvmti/interp/getstacktrace.jar b/libjava/testsuite/libjava.jvmti/interp/getstacktrace.jar
new file mode 100644
index 00000000000..14b084a4de1
--- /dev/null
+++ b/libjava/testsuite/libjava.jvmti/interp/getstacktrace.jar
diff --git a/libjava/testsuite/libjava.jvmti/interp/getstacktrace.java b/libjava/testsuite/libjava.jvmti/interp/getstacktrace.java
new file mode 100644
index 00000000000..21a21f0fbb1
--- /dev/null
+++ b/libjava/testsuite/libjava.jvmti/interp/getstacktrace.java
@@ -0,0 +1,88 @@
+public class getstacktrace
+  extends Thread
+{
+  public boolean done = false;
+
+  // num_frames is the number of frames > the original run () call so if
+  // num_frames = 1, the thread will have 2 frames, the original Thread.run
+  // call, plus one additional
+  public int num_frames, thread_num;
+
+  public static int num_threads = 1;
+
+  static
+    {
+      System.loadLibrary("natgetstacktrace");
+    }
+
+  public void run ()
+  {
+    thread_num = num_threads++;
+    num_frames = thread_num;
+
+    if (num_frames <= 1)
+      {
+        natRunner ();
+      }
+    else
+      {
+        if (thread_num % 2 == 0)
+          natPlaceholder ();
+        else
+          placeholder ();
+      }
+  }
+
+  public void placeholder ()
+  {
+    num_frames--;
+    if (num_frames <= 1)
+      {
+        if (thread_num % 2 == 1)
+          natRunner ();
+        else
+          runner ();
+      }
+    else
+      {
+        if (thread_num % 2 == 0)
+          natPlaceholder ();
+        else
+          placeholder ();
+      }
+  }
+  
+  public void runner ()
+  {
+    done = true;
+    while (done)
+      yield ();
+  }
+
+  public native void natPlaceholder ();
+  public native void natRunner ();
+
+  public static native int do_getstacktrace_tests (Thread[] threads);
+
+  public static void main (String[] args)
+  {
+    System.out.println ("JVMTI GetStackTrace Interpreted Test");
+
+    getstacktrace[] threads = new getstacktrace[10];
+
+    for (int i = 0; i < threads.length; i++)
+      {
+        threads[i] = new getstacktrace ();
+        threads[i].start ();
+        while (!threads[i].done)
+          yield ();
+      }
+
+    do_getstacktrace_tests (threads);
+
+    for (int i = 0; i < threads.length; i++)
+      {
+        threads[i].done = false;
+      }
+  }
+}
diff --git a/libjava/testsuite/libjava.jvmti/interp/getstacktrace.out b/libjava/testsuite/libjava.jvmti/interp/getstacktrace.out
new file mode 100644
index 00000000000..5134e6eab78
--- /dev/null
+++ b/libjava/testsuite/libjava.jvmti/interp/getstacktrace.out
@@ -0,0 +1,76 @@
+JVMTI GetStackTrace Interpreted Test
+Thread has 2 frames
+Frame 0 is native
+Frame 1 is interpreted
+Thread has 3 frames
+Frame 0 is interpreted
+Frame 1 is native
+Frame 2 is interpreted
+Thread has 4 frames
+Frame 0 is native
+Frame 1 is interpreted
+Frame 2 is interpreted
+Frame 3 is interpreted
+Thread has 5 frames
+Frame 0 is interpreted
+Frame 1 is native
+Frame 2 is native
+Frame 3 is native
+Frame 4 is interpreted
+Thread has 6 frames
+Frame 0 is native
+Frame 1 is interpreted
+Frame 2 is interpreted
+Frame 3 is interpreted
+Frame 4 is interpreted
+Frame 5 is interpreted
+Thread has 7 frames
+Frame 0 is interpreted
+Frame 1 is native
+Frame 2 is native
+Frame 3 is native
+Frame 4 is native
+Frame 5 is native
+Frame 6 is interpreted
+Thread has 8 frames
+Frame 0 is native
+Frame 1 is interpreted
+Frame 2 is interpreted
+Frame 3 is interpreted
+Frame 4 is interpreted
+Frame 5 is interpreted
+Frame 6 is interpreted
+Frame 7 is interpreted
+Thread has 9 frames
+Frame 0 is interpreted
+Frame 1 is native
+Frame 2 is native
+Frame 3 is native
+Frame 4 is native
+Frame 5 is native
+Frame 6 is native
+Frame 7 is native
+Frame 8 is interpreted
+Thread has 10 frames
+Frame 0 is native
+Frame 1 is interpreted
+Frame 2 is interpreted
+Frame 3 is interpreted
+Frame 4 is interpreted
+Frame 5 is interpreted
+Frame 6 is interpreted
+Frame 7 is interpreted
+Frame 8 is interpreted
+Frame 9 is interpreted
+Thread has 11 frames
+Frame 0 is interpreted
+Frame 1 is native
+Frame 2 is native
+Frame 3 is native
+Frame 4 is native
+Frame 5 is native
+Frame 6 is native
+Frame 7 is native
+Frame 8 is native
+Frame 9 is native
+Frame 10 is interpreted
diff --git a/libjava/testsuite/libjava.jvmti/interp/natgetstacktrace.cc b/libjava/testsuite/libjava.jvmti/interp/natgetstacktrace.cc
new file mode 100644
index 00000000000..e2c88ada40c
--- /dev/null
+++ b/libjava/testsuite/libjava.jvmti/interp/natgetstacktrace.cc
@@ -0,0 +1,144 @@
+#include <jni.h>
+
+#include <jvmti.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <unistd.h>
+
+#include "getstacktrace.h"
+
+void
+printStackTrace (jvmtiFrameInfo *frames, jint frame_cnt)
+{
+  printf ("Thread has %d frames\n", static_cast<int> (frame_cnt));
+
+  for (int i = 0; i < frame_cnt; i++)
+    {
+      jmethodID method = frames[i].method;
+      jlocation location = frames[i].location;
+
+      if (location == -1)
+        {
+          printf ("Frame %d is native\n", i);
+        }
+      else
+        {
+          printf ("Frame %d is interpreted\n", i);
+        }
+    }
+}
+
+
+JNIEXPORT void JNICALL Java_getstacktrace_natPlaceholder (JNIEnv *env, jobject obj)
+{
+  jclass klass = env->GetObjectClass (obj);
+  jfieldID done_id = env->GetFieldID (klass, "done", "Z");
+  jfieldID num_frames_id = env->GetFieldID (klass, "num_frames", "I");
+  jfieldID thread_num_id = env->GetFieldID (klass, "thread_num", "I");
+
+  // num_frames--
+  jint n_frames = env->GetIntField (obj, num_frames_id);
+  n_frames--;
+  env->SetIntField (obj, num_frames_id, n_frames);
+
+  jint t_num = env->GetIntField (obj, thread_num_id);
+
+  if (n_frames <= 1)
+    {
+      if (t_num % 2 == 1)
+        {
+          jmethodID natRunner_id = env->GetMethodID (klass, "natRunner", "()V");
+          env->CallVoidMethod (obj, natRunner_id);
+        }
+      else
+        {
+          jmethodID runner_id = env->GetMethodID (klass, "runner", "()V");
+          env->CallVoidMethod (obj, runner_id);
+        }
+    }
+  else
+    {
+      if (t_num % 2 == 0)
+        {
+          jmethodID natPlaceholder_id = env->GetMethodID (klass,
+                                        "natPlaceholder",
+                                        "()V");
+          env->CallVoidMethod (obj, natPlaceholder_id);
+        }
+      else
+        {
+          jmethodID placeholder_id = env->GetMethodID (klass, "placeholder",
+                                     "()V");
+          env->CallVoidMethod (obj, placeholder_id);
+        }
+    }
+}
+
+JNIEXPORT void JNICALL Java_getstacktrace_natRunner (JNIEnv *env, jobject obj)
+{
+  jclass klass = env->GetObjectClass (obj);
+  jfieldID done_id = env->GetFieldID (klass, "done", "Z");
+
+
+  jboolean done;
+  done = true;
+  env->SetBooleanField (obj, done_id, done);
+
+  do
+    {
+      done = env->GetBooleanField (obj, done_id);
+      if (done == false)
+        break;
+      usleep (10);
+    }
+  while (done != false);
+}
+
+JNIEXPORT jint JNICALL Java_getstacktrace_do_1getstacktrace_1tests
+(JNIEnv *env, jclass klass, jobjectArray thr_arr)
+{
+  JavaVM *vm;
+  jint err = env->GetJavaVM (&vm);
+  if (err < 0)
+    {
+      fprintf (stderr, "error getting VM\n");
+      exit (1);
+    }
+
+  jvmtiEnv *jvmti = NULL;
+  vm->GetEnv ((void **) &jvmti, JVMTI_VERSION_1_0);
+
+  if (jvmti == NULL)
+    {
+      fprintf (stderr, "error getting jvmti environment\n");
+      exit (1);
+    }
+
+  jint frame_cnt;
+  jvmtiFrameInfo frames[30];
+
+  jvmtiError jerr;
+  jthread thr;
+
+  jsize num_threads = env->GetArrayLength (thr_arr);
+
+  for (int i = 0; i < num_threads; i++)
+    {
+      thr = reinterpret_cast<jthread>
+            (env->GetObjectArrayElement (thr_arr, static_cast<jsize> (i)));
+      fflush (stdout);
+      jerr = jvmti->GetStackTrace (thr, 0, 30, frames, &frame_cnt);
+      if (jerr != JVMTI_ERROR_NONE)
+        {
+          char *error_name;
+          jvmti->GetErrorName (jerr, &error_name);
+          fprintf (stderr, "JVMTI Error: %s\n", error_name);
+          jvmti->Deallocate (reinterpret_cast<unsigned char *> (error_name));
+        }
+      else
+        {
+          printStackTrace (frames, frame_cnt);
+        }
+    }
+}