Added VM support for isolate stacktrace status.

runtime/vm/isolate.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 "vm/isolate.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
+#include "platform/json.h"
 #include "lib/mirrors.h"
 #include "vm/code_observers.h"
 #include "vm/compiler_stats.h"
 #include "vm/dart_api_state.h"
 #include "vm/dart_entry.h"
 #include "vm/debugger.h"
 #include "vm/heap.h"
 #include "vm/message_handler.h"
 #include "vm/object_store.h"
 #include "vm/parser.h"
@@ skipping 316 matching lines @@
       stack_limit_(0),
       saved_stack_limit_(0),
       message_handler_(NULL),
       spawn_data_(0),
       gc_prologue_callbacks_(),
       gc_epilogue_callbacks_(),
       deopt_cpu_registers_copy_(NULL),
       deopt_fpu_registers_copy_(NULL),
       deopt_frame_copy_(NULL),
       deopt_frame_copy_size_(0),
-      deferred_objects_(NULL) {
+      deferred_objects_(NULL),
+      stacktrace_(NULL),
+      stack_frame_index_(-1) {
 }
 
 
 Isolate::~Isolate() {
   delete [] name_;
   delete heap_;
   delete object_store_;
   delete api_state_;
   delete stub_code_;
   delete debugger_;
@@ skipping 272 matching lines @@
 
 
 Dart_IsolateCreateCallback Isolate::create_callback_ = NULL;
 Dart_IsolateInterruptCallback Isolate::interrupt_callback_ = NULL;
 Dart_IsolateUnhandledExceptionCallback
     Isolate::unhandled_exception_callback_ = NULL;
 Dart_IsolateShutdownCallback Isolate::shutdown_callback_ = NULL;
 Dart_FileOpenCallback Isolate::file_open_callback_ = NULL;
 Dart_FileWriteCallback Isolate::file_write_callback_ = NULL;
 Dart_FileCloseCallback Isolate::file_close_callback_ = NULL;
+Dart_IsolateInterruptCallback Isolate::vmstats_callback_ = NULL;
 
 
 void Isolate::VisitObjectPointers(ObjectPointerVisitor* visitor,
                                   bool visit_prologue_weak_handles,
                                   bool validate_frames) {
   ASSERT(visitor != NULL);
 
   // Visit objects in the object store.
   object_store()->VisitObjectPointers(visitor);
 
@@ skipping 34 matching lines @@
 
 
 void Isolate::VisitWeakPersistentHandles(HandleVisitor* visitor,
                                          bool visit_prologue_weak_handles) {
   if (api_state() != NULL) {
     api_state()->VisitWeakHandles(visitor, visit_prologue_weak_handles);
   }
 }
 
 
+static Monitor* status_sync;

[siva, 2013/04/01 22:07:55]

= NULL;

[Tom Ball, 2013/04/02 16:49:16]

Done.

+
+bool Isolate::FetchStacktrace() {
+  Isolate* isolate = Isolate::Current();
+  MonitorLocker ml(status_sync);
+  DebuggerStackTrace* stack = Debugger::CollectStackTrace();
+  TextBuffer buffer(256);
+  buffer.Printf("{ \"handle\": \"0x%"Px64"\", \"stacktrace\": [ ",
+                reinterpret_cast<int64_t>(isolate));
+  intptr_t n_frames = stack->Length();
+  String& url = String::Handle();
+  String& function = String::Handle();
+  for (int i = 0; i < n_frames; i++) {
+    if (i > 0) {
+      buffer.Printf(", ");
+    }
+    ActivationFrame* frame = stack->ActivationFrameAt(i);
+    url ^= frame->SourceUrl();
+    function ^= frame->function().UserVisibleName();
+    buffer.Printf("{ \"url\": \"%s\", ", url.ToCString());
+    buffer.Printf("\"line\": %d, ", frame->LineNumber());
+    buffer.Printf("\"function\": \"%s\", ", function.ToCString());
+
+    const Code& code = frame->code();
+    buffer.Printf("\"code\": { ");
+    buffer.Printf("\"alive\": %s, ", code.is_alive() ? "false" : "true");
+    buffer.Printf("\"optimized\": %s }}",
+        code.is_optimized() ? "false" : "true");
+  }
+  buffer.Printf("]}");
+  isolate->stacktrace_ = strndup(buffer.buf(), buffer.length());

[siva, 2013/04/01 22:07:55]

I guess with a little tweak to the implementation of TextBuffer it would be
possible to avoid this copy, I guess we can do that in a different CL.

[Tom Ball, 2013/04/02 16:49:16]

Agreed.

+  ml.Notify();
+  return true;
+}
+
+
+bool Isolate::FetchStackFrameDetails() {
+  Isolate* isolate = Isolate::Current();
+  ASSERT(isolate->stack_frame_index_ >= 0);
+  MonitorLocker ml(status_sync);
+  DebuggerStackTrace* stack = Debugger::CollectStackTrace();
+  intptr_t frame_index = isolate->stack_frame_index_;
+  if (frame_index >= stack->Length()) {
+    // Frame no longer available.
+    return NULL;
+  }
+  ActivationFrame* frame = stack->ActivationFrameAt(frame_index);
+  TextBuffer buffer(256);
+  buffer.Printf("{ \"handle\": \"0x%"Px64"\", \"frame_index\": %"Pd", ",
+       reinterpret_cast<int64_t>(isolate), frame_index);
+
+  const Code& code = frame->code();
+  buffer.Printf("\"code\": { \"size\": %"Pd", ", code.Size());
+  buffer.Printf("\"alive\": %s, ", code.is_alive() ? "false" : "true");
+  buffer.Printf("\"optimized\": %s }, ",
+      code.is_optimized() ? "false" : "true");
+  // TODO(tball): add compilation stats (time, etc.), when available.
+
+  buffer.Printf("\"local_vars\": [ ");
+  intptr_t n_local_vars = frame->NumLocalVariables();
+  String& var_name = String::Handle();
+  Instance& value = Instance::Handle();
+  for (int i = 0; i < n_local_vars; i++) {
+    if (i > 0) {
+      buffer.Printf(", ");
+    }
+    intptr_t token_pos, end_pos;
+    frame->VariableAt(i, &var_name, &token_pos, &end_pos, &value);
+    buffer.Printf(
+        "{ \"name\": \"%s\", \"pos\": %d, \"end_pos\": %d, "
+        "\"value\": \"%s\" }",
+        var_name.ToCString(), token_pos, end_pos, value.ToCString());
+  }
+  buffer.Printf("]}");
+  isolate->stacktrace_ = strndup(buffer.buf(), buffer.length());
+  ml.Notify();
+  return true;
+}
+
+
+char* Isolate::DoStacktraceInterrupt(Dart_IsolateInterruptCallback cb) {
+  ASSERT(stacktrace_ == NULL);
+  SetVmStatsCallback(cb);
+  if (status_sync == NULL) {
+    status_sync = new Monitor();
+  }
+  ScheduleInterrupts(Isolate::kVmStatusInterrupt);
+  {
+    MonitorLocker ml(status_sync);
+    ml.Wait();

[siva, 2013/04/01 22:07:55]

I think you need to test a condition in a while loop before
going into wait. It is possible that the other thread might have already done a
notify before you went into wait.

[Tom Ball, 2013/04/02 16:49:16]

Added a test that stacktrace_ is still NULL before waiting.

+  }
+  SetVmStatsCallback(NULL);
+  ASSERT(stacktrace_ != NULL);
+  // result is freed by VmStats::WebServer().
+  char* result = stacktrace_;
+  stacktrace_ = NULL;
+  return result;
+}
+
+
+char* Isolate::GetStatusStacktrace() {
+  return DoStacktraceInterrupt(&FetchStacktrace);
+}
+
+char* Isolate::GetStatusStackFrame(intptr_t index) {
+  ASSERT(index >= 0);
+  stack_frame_index_ = index;
+  char* result = DoStacktraceInterrupt(&FetchStackFrameDetails);
+  stack_frame_index_ = -1;
+  return result;
+}
+
+
+// Returns the isolate's general detail information.
+char* Isolate::GetStatusDetails() {
+  const char* format = "{\n"
+      "  \"handle\": \"0x%"Px64"\",\n"
+      "  \"name\": \"%s\",\n"
+      "  \"port\": %"Pd",\n"
+      "  \"starttime\": %"Pd",\n"
+      "  \"stacklimit\": %"Pd",\n"
+      "  \"newspace\": {\n"
+      "    \"used\": %"Pd",\n"
+      "    \"capacity\": %"Pd"\n"
+      "  },\n"
+      "  \"oldspace\": {\n"
+      "    \"used\": %"Pd",\n"
+      "    \"capacity\": %"Pd"\n"
+      "  }\n"
+      "}";
+  char buffer[300];
+  int64_t address = reinterpret_cast<int64_t>(this);
+  int n = OS::SNPrint(buffer, 300, format, address, name(), main_port(),
+                      (start_time() / 1000L), saved_stack_limit(),
+                      heap()->Used(Heap::kNew) / KB,
+                      heap()->Capacity(Heap::kNew) / KB,
+                      heap()->Used(Heap::kOld) / KB,
+                      heap()->Capacity(Heap::kOld) / KB);
+  ASSERT(n < 300);
+  return strdup(buffer);
+}
+
+
 char* Isolate::GetStatus(const char* request) {
   char* p = const_cast<char*>(request);
   const char* service_type = "/isolate/";
-  ASSERT(strncmp(p, service_type, strlen(service_type)) == 0);
+  ASSERT(!strncmp(p, service_type, strlen(service_type)));
   p += strlen(service_type);
 
   // Extract isolate handle.
   int64_t addr;
   OS::StringToInt64(p, &addr);
   Isolate* isolate = reinterpret_cast<Isolate*>(addr);

[siva, 2013/04/01 22:07:55]

Is there a way to assert that this addr is a valid isolate?

[Tom Ball, 2013/04/02 16:49:16]

File issue 9600, and added TODO.

-  Heap* heap = isolate->heap();
+  p += strcspn(p, "/");
 
-  char buffer[256];
-  int64_t port = isolate->main_port();
-  int64_t start_time = (isolate->start_time() / 1000L);
-#if defined(TARGET_ARCH_X64)
-  const char* format = "{\n"
-      "  \"name\": \"%s\",\n"
-      "  \"port\": %ld,\n"
-      "  \"starttime\": %ld,\n"
-      "  \"stacklimit\": %ld,\n"
-      "  \"newspace\": {\n"
-      "    \"used\": %ld,\n"
-      "    \"capacity\": %ld\n"
-      "  },\n"
-      "  \"oldspace\": {\n"
-      "    \"used\": %ld,\n"
-      "    \"capacity\": %ld\n"
-      "  }\n"
-      "}";
-#else
-  const char* format = "{\n"
-      "  \"name\": \"%s\",\n"
-      "  \"port\": %lld,\n"
-      "  \"starttime\": %lld,\n"
-      "  \"stacklimit\": %d,\n"
-      "  \"newspace\": {\n"
-      "    \"used\": %d,\n"
-      "    \"capacity\": %d\n"
-      "  },\n"
-      "  \"oldspace\": {\n"
-      "    \"used\": %d,\n"
-      "    \"capacity\": %d\n"
-      "  }\n"
-      "}";
-#endif
-  int n = OS::SNPrint(buffer, 256, format, isolate->name(), port, start_time,
-                      isolate->saved_stack_limit(),
-                      heap->Used(Heap::kNew) / KB,
-                      heap->Capacity(Heap::kNew) / KB,
-                      heap->Used(Heap::kOld) / KB,
-                      heap->Capacity(Heap::kOld) / KB);
-  ASSERT(n < 256);
-  return strdup(buffer);
+  // Query "/isolate/<handle>".
+  if (strlen(p) == 0) {
+    return isolate->GetStatusDetails();
+  }
+
+  // Query "/isolate/<handle>/stacktrace"
+  if (!strcmp(p, "/stacktrace")) {
+    return isolate->GetStatusStacktrace();
+  }
+
+  // Query "/isolate/<handle>/stacktrace/<frame-index>"
+  const char* stacktrace_query = "/stacktrace/";
+  int64_t frame_index = -1;
+  if (!strncmp(p, stacktrace_query, strlen(stacktrace_query))) {
+    p += strlen(stacktrace_query);
+    OS::StringToInt64(p, &frame_index);
+    if (frame_index >= 0) {
+      return isolate->GetStatusStackFrame(frame_index);
+    }
+  }
+
+  // TODO(tball): "/isolate/<handle>/stacktrace/<frame-index>"/disassemble"
+
+  return NULL;  // Unimplemented query.
 }
 
 }  // namespace dart