Track async causal stack traces

runtime/vm/stack_trace.cc

Index: runtime/vm/stack_trace.cc
diff --git a/runtime/vm/stack_trace.cc b/runtime/vm/stack_trace.cc
new file mode 100644
index 0000000000000000000000000000000000000000..0168e3bc74c92c498fcc73b2a296d60ecfb0e4f1
--- /dev/null
+++ b/runtime/vm/stack_trace.cc
@@ -0,0 +1,117 @@
+// Copyright (c) 2017, 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 "vm/stack_frame.h"
+#include "vm/stack_trace.h"
+
+namespace dart {
+
+// Count the number of frames that are on the stack.
+intptr_t StackTraceUtils::CountFrames(Thread* thread,
+                                      int skip_frames,
+                                      const Function& async_function,
+                                      bool count_invisible_frames) {
+  Zone* zone = thread->zone();
+  intptr_t frame_count = 0;
+  StackFrameIterator frames(StackFrameIterator::kDontValidateFrames);
+  StackFrame* frame = frames.NextFrame();
+  ASSERT(frame != NULL);  // We expect to find a dart invocation frame.
+  Code& code = Code::Handle(zone);
+  Function& function = Function::Handle(zone);
+  const bool async_function_is_null = async_function.IsNull();
+  while (frame != NULL) {
+    if (frame->IsDartFrame()) {
+      if (skip_frames > 0) {
+        skip_frames--;
+      } else {
+        code = frame->LookupDartCode();
+        function = code.function();
+        if (function.is_visible() || count_invisible_frames) {
+          frame_count++;
+        }
+        if (!async_function_is_null &&
+            (async_function.raw() == function.parent_function())) {
+          return frame_count;
+        }
+      }
+    }
+    frame = frames.NextFrame();
+  }
+  // We hit the sentinel.
+  ASSERT(async_function_is_null);
+  return frame_count;
+}
+
+
+intptr_t StackTraceUtils::CollectFrames(Thread* thread,
+                                        const Array& code_array,
+                                        const Array& pc_offset_array,
+                                        intptr_t array_offset,
+                                        intptr_t count,
+                                        int skip_frames,
+                                        bool collect_invisible_frames) {
+  Zone* zone = thread->zone();
+  StackFrameIterator frames(StackFrameIterator::kDontValidateFrames);
+  StackFrame* frame = frames.NextFrame();
+  ASSERT(frame != NULL);  // We expect to find a dart invocation frame.
+  Function& function = Function::Handle(zone);
+  Code& code = Code::Handle(zone);
+  Smi& offset = Smi::Handle(zone);
+  intptr_t collected_frames_count = 0;
+  while ((frame != NULL) && (collected_frames_count < count)) {
+    if (frame->IsDartFrame()) {
+      if (skip_frames > 0) {
+        skip_frames--;
+      } else {
+        code = frame->LookupDartCode();
+        function = code.function();
+        if (function.is_visible() || collect_invisible_frames) {
+          offset = Smi::New(frame->pc() - code.PayloadStart());
+          code_array.SetAt(array_offset, code);
+          pc_offset_array.SetAt(array_offset, offset);
+          array_offset++;
+          collected_frames_count++;
+        }
+      }
+    }
+    frame = frames.NextFrame();
+  }
+  return collected_frames_count;
+}
+
+
+intptr_t StackTraceUtils::ExtractAsyncStackTraceInfo(
+    Thread* thread,
+    Function* async_function,
+    StackTrace* async_stack_trace_out,
+    Array* async_code_array,
+    Array* async_pc_offset_array) {
+  if (thread->async_stack_trace() == StackTrace::null()) {
+    return 0;
+  }
+  *async_stack_trace_out = thread->async_stack_trace();
+  ASSERT(!async_stack_trace_out->IsNull());
+  const StackTrace& async_stack_trace =
+      StackTrace::Handle(thread->async_stack_trace());
+  const intptr_t async_stack_trace_length = async_stack_trace.Length();
+  // At least two entries (0: gap marker, 1: async function).
+  ASSERT(async_stack_trace_length >= 2);
+  // Validate the structure of this stack trace.
+  *async_code_array = async_stack_trace.code_array();
+  ASSERT(!async_code_array->IsNull());
+  *async_pc_offset_array = async_stack_trace.pc_offset_array();
+  ASSERT(!async_pc_offset_array->IsNull());
+  // We start with the asynchronous gap marker.
+  ASSERT(async_code_array->At(0) != Code::null());
+  ASSERT(async_code_array->At(0) ==
+         StubCode::AsynchronousGapMarker_entry()->code());
+  const Code& code = Code::Handle(Code::RawCast(async_code_array->At(1)));
+  *async_function = code.function();
+  ASSERT(!async_function->IsNull());
+  ASSERT(async_function->IsAsyncFunction() ||
+         async_function->IsAsyncGenerator());
+  return async_stack_trace_length;
+}
+
+}  // namespace dart