lib,src: enable TTD auto-trace config

Also updated TTD Readme

PR-URL: #543
Reviewed-By: Jimmy Thomson <jithomso@microsoft.com>
Reviewed-By: Kyle Farnung <kfarnung@microsoft.com>

Author: mrkmarron

TTD-README.md

@@ -63,27 +63,25 @@ to understand the problem.
 
 TTD functionality is available in Node-ChakraCore and is supported by
 [VSCode](https://code.visualstudio.com/). You can use VSCode to debug diagnostic
-traces even if you don't have the project sources available. This is done by:
-- Creating an empty `dummy.js` file in the trace directory.
-- Adding the following configuration into your `.vscode\launch.json`
-  configuration file.
+traces even if you don't have the project sources available. This is done by
+adding the following configuration into your `.vscode\launch.json`configuration
+file.
 
 ```json
 {
     "name": "Trace Debug",
     "type": "node",
     "request": "launch",
     "stopOnEntry": true,
-    "program": "${workspaceRoot}/dummy.js",
     "windows": { "runtimeExecutable": "nvs.cmd" },
     "osx": { "runtimeExecutable": "nvs" },
     "linux": { "runtimeExecutable": "nvs" },
     "runtimeArgs": [
         "run",
-        "chakracore-nightly",
+        "chakracore",
         "--nolazy",
         "--break-first",
-        "--replay-debug=./"
+        "--replay-debug=[path to trace directory]"
     ],
     "console": "internalConsole"
 }

lib/trace_mgr.js

@@ -489,13 +489,13 @@ function generateFuzzyStack(eventKind) {
       return directIsAbsolute(frame);
     });
 
-  const lastframe = errstk.length > 0 ?
-    errstk[errstk.length - 1] :
-    'empty_stack';
-
-  const fname = lastframe.substr(lastframe.lastIndexOf(path.sep) + 1)
+  let fname = 'empty_stack';
+  if (errstk.length !== 0) {
+    const lastframe = errstk[errstk.length - 1];
+    fname = lastframe.substr(lastframe.lastIndexOf(path.sep) + 1)
       .replace('.js:', '_line-')
       .replace(':', '_column-');
+  }
 
   // Identify which frames are recursive (appear multiple times in the stack)
   const recFrames = new Map();

src/chakra_ttd.h

@@ -11,6 +11,7 @@
 extern bool s_doTTRecord;
 extern bool s_doTTReplay;
 extern bool s_doTTEnableDebug;
+extern bool s_ttAutoTraceEnabled;
 #endif
 
 #endif  // SRC_CHAKRA_TTD_H_

src/node.cc

@@ -126,6 +126,7 @@ bool s_doTTRecord = false;
 bool s_doTTReplay = false;
 bool s_doTTEnableDebug = false;
 size_t s_ttoptReplayUriLength = 0;
+bool s_ttAutoTraceEnabled = true;
 const char* s_ttoptReplayUri = nullptr;
 uint32_t s_ttdSnapInterval = 2000;
 uint32_t s_ttdSnapHistoryLength = 2;
@@ -3582,6 +3583,8 @@ static void PrintHelp() {
          "  --replay-debug=dir         replay and debug using recording log\n"
          "  --break-first              break at first statement when running\n"
          "                             in --replay-debug mode\n"
+         "  --disable-auto-trace       disable the auto-trace feature during\n"
+         "                             record\n"
  #endif
          "  --track-heap-objects       track heap object allocations for heap "
          "snapshots\n"
@@ -3914,6 +3917,8 @@ static void ParseArgs(int* argc,
     } else if (strstr(arg, "--record-history=") == arg) {
       const char* historyStr = arg + strlen("--record-history=");
       s_ttdSnapHistoryLength = (uint32_t)atoi(historyStr);
+    } else if (strcmp(arg, "--disable-auto-trace") == 0) {
+      s_ttAutoTraceEnabled = false;
     } else if (strstr(arg, "-TTRecord:") == arg) {
       TTDFlagWarning(arg, "--record");
     } else if (strstr(arg, "-TTReplay:") == arg) {
@@ -4676,6 +4681,10 @@ inline int Start(Isolate* isolate, void* isolate_context,
   if (s_doTTRecord) {
     fprintf(stderr, "Recording started (after main module loaded)...\n");
     JsTTDStart();
+
+    if (!s_ttAutoTraceEnabled) {
+      JsTTDDiagSetAutoTraceStatus(s_ttAutoTraceEnabled);
+    }
   }
 #endif