Track async causal stack traces

runtime/lib/stacktrace.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "lib/stacktrace.h"
 #include "vm/bootstrap_natives.h"
+#include "vm/debugger.h"
 #include "vm/exceptions.h"
+#include "vm/native_entry.h"
 #include "vm/object_store.h"
 #include "vm/runtime_entry.h"
 #include "vm/stack_frame.h"
+#include "vm/stack_trace.h"
 
 namespace dart {
 
-static void IterateFrames(const GrowableObjectArray& code_list,
-                          const GrowableObjectArray& pc_offset_list,
-                          int skip_frames) {
+DECLARE_FLAG(bool, show_invisible_frames);
+DEFINE_FLAG(int,
+            max_async_stack_trace_frames,
+            96,
+            "Maximum number of asynchronous stack traces frames remembered in "
+            "an asynchronous function activation");

[siva, 2017/02/08 18:46:28]

These flags don't seem to be used anymore, can they be removed?

[Cutch, 2017/02/09 22:45:50]

Removed.

+
+static RawStackTrace* CurrentSyncStackTrace(Thread* thread) {
+  Zone* zone = thread->zone();
+  const Function& null_function = Function::ZoneHandle(zone);
+  // Skip the Dart exit frame.
+  const intptr_t skip_frames = 1;
+
+  // Determine how big the stack trace is.
+  const intptr_t stack_trace_length =
+      StackTraceUtils::CountFrames(skip_frames, null_function);

[siva, 2017/02/08 18:46:28]

Pass thread into this function too?

[Cutch, 2017/02/09 22:45:50]

Done.

+
+  // Allocate once.
+  const Array& code_array =
+      Array::ZoneHandle(zone, Array::New(stack_trace_length));
+  const Array& pc_offset_array =
+      Array::ZoneHandle(zone, Array::New(stack_trace_length));
+
+  // Collect the frames.
+  const intptr_t collected_frames_count = StackTraceUtils::CollectFrames(
+      thread, code_array, pc_offset_array, 0, stack_trace_length, skip_frames);
+
+  ASSERT(collected_frames_count == stack_trace_length);
+
+  return StackTrace::New(code_array, pc_offset_array);
+}
+
+
+static RawStackTrace* CurrentStackTrace(
+    Thread* thread,
+    bool for_async_function,
+    intptr_t skip_frames = 1,
+    bool causal_async_stacks = FLAG_causal_async_stacks) {
+  if (!causal_async_stacks) {
+    // Return the synchronous stack trace.
+    return CurrentSyncStackTrace(thread);
+  }
+
+  Zone* zone = thread->zone();
+  Code& code = Code::ZoneHandle(zone);
+  Smi& offset = Smi::ZoneHandle(zone);
+  Function& async_function = Function::ZoneHandle(zone);
+  StackTrace& async_stack_trace = StackTrace::ZoneHandle(zone);
+  Array& async_code_array = Array::ZoneHandle(zone);
+  Array& async_pc_offset_array = Array::ZoneHandle(zone);
+
+  StackTraceUtils::ExtractAsyncStackTraceInfo(
+      thread, &async_function, &async_stack_trace, &async_code_array,
+      &async_pc_offset_array);
+
+  // Determine the size of the stack trace.
+  const intptr_t extra_frames = for_async_function ? 1 : 0;
+  const intptr_t synchronous_stack_trace_length =
+      StackTraceUtils::CountFrames(skip_frames, async_function);
+
+  const intptr_t capacity = synchronous_stack_trace_length +
+                            extra_frames;  // For the asynchronous gap.
+
+  // Allocate memory for the stack trace.
+  const Array& code_array = Array::ZoneHandle(zone, Array::New(capacity));
+  const Array& pc_offset_array = Array::ZoneHandle(zone, Array::New(capacity));
+
+  intptr_t write_cursor = 0;
+  if (for_async_function) {
+    // Place the asynchronous gap marker at the top of the stack trace.
+    code = StubCode::AsynchronousGapMarker_entry()->code();
+    ASSERT(!code.IsNull());
+    offset = Smi::New(0);
+    code_array.SetAt(write_cursor, code);
+    pc_offset_array.SetAt(write_cursor, offset);
+    write_cursor++;
+  }
+
+  // Append the synchronous stack trace.
+  const intptr_t collected_frames_count = StackTraceUtils::CollectFrames(
+      thread, code_array, pc_offset_array, write_cursor,
+      synchronous_stack_trace_length, skip_frames);
+
+  write_cursor += collected_frames_count;
+
+  ASSERT(write_cursor == capacity);
+
+  return StackTrace::New(code_array, pc_offset_array, async_stack_trace);
+}
+
+
+RawStackTrace* GetStackTraceForException() {
+  Thread* thread = Thread::Current();
+  return CurrentStackTrace(thread, false, 0);
+}
+
+
+DEFINE_NATIVE_ENTRY(StackTrace_current, 0) {
+  return CurrentStackTrace(thread, false);
+}
+
+
+DEFINE_NATIVE_ENTRY(StackTrace_asyncStackTraceHelper, 0) {
+  return CurrentStackTrace(thread, true);
+}
+
+
+DEFINE_NATIVE_ENTRY(StackTrace_clearAsyncThreadStackTrace, 0) {
+  thread->clear_async_stack_trace();
+  return Object::null();
+}
+
+
+DEFINE_NATIVE_ENTRY(StackTrace_setAsyncThreadStackTrace, 1) {
+  GET_NON_NULL_NATIVE_ARGUMENT(StackTrace, stack_trace,
+                               arguments->NativeArgAt(0));
+  thread->set_async_stack_trace(stack_trace);
+  return Object::null();
+}
+
+
+static void AppendFrames(const GrowableObjectArray& code_list,
+                         const GrowableObjectArray& pc_offset_list,
+                         int skip_frames) {
   StackFrameIterator frames(StackFrameIterator::kDontValidateFrames);
   StackFrame* frame = frames.NextFrame();
   ASSERT(frame != NULL);  // We expect to find a dart invocation frame.
   Code& code = Code::Handle();
   Smi& offset = Smi::Handle();
   while (frame != NULL) {
     if (frame->IsDartFrame()) {
       if (skip_frames > 0) {
         skip_frames--;
       } else {
         code = frame->LookupDartCode();
         offset = Smi::New(frame->pc() - code.PayloadStart());
         code_list.Add(code);
         pc_offset_list.Add(offset);
       }
     }
     frame = frames.NextFrame();
   }
 }
 
+
 // Creates a StackTrace object from the current stack.
 //
 // Skips the first skip_frames Dart frames.
 const StackTrace& GetCurrentStackTrace(int skip_frames) {
   const GrowableObjectArray& code_list =
       GrowableObjectArray::Handle(GrowableObjectArray::New());
   const GrowableObjectArray& pc_offset_list =
       GrowableObjectArray::Handle(GrowableObjectArray::New());
-  IterateFrames(code_list, pc_offset_list, skip_frames);
+  AppendFrames(code_list, pc_offset_list, skip_frames);
   const Array& code_array = Array::Handle(Array::MakeArray(code_list));
   const Array& pc_offset_array =
       Array::Handle(Array::MakeArray(pc_offset_list));
   const StackTrace& stacktrace =
       StackTrace::Handle(StackTrace::New(code_array, pc_offset_array));
   return stacktrace;
 }
 
+
 // An utility method for convenient printing of dart stack traces when
 // inside 'gdb'. Note: This function will only work when there is a
 // valid exit frame information. It will not work when a breakpoint is
 // set in dart code and control is got inside 'gdb' without going through
 // the runtime or native transition stub.
 void _printCurrentStackTrace() {
   const StackTrace& stacktrace = GetCurrentStackTrace(0);
   OS::PrintErr("=== Current Trace:\n%s===\n", stacktrace.ToCString());
 }
 
+
 // Like _printCurrentStackTrace, but works in a NoSafepointScope.
 void _printCurrentStackTraceNoSafepoint() {
   StackFrameIterator frames(StackFrameIterator::kDontValidateFrames);
   StackFrame* frame = frames.NextFrame();
   while (frame != NULL) {
-    OS::Print("%s\n", frame->ToCString());
+    OS::PrintErr("%s\n", frame->ToCString());
     frame = frames.NextFrame();
   }
 }
 
-DEFINE_NATIVE_ENTRY(StackTrace_current, 0) {
-  const StackTrace& stacktrace = GetCurrentStackTrace(1);
-  return stacktrace.raw();
-}
-
 }  // namespace dart