log stack traces

internal/engine.cm

@@ -324,6 +324,7 @@ var log_config = null
 var channel_sinks = {}
 var wildcard_sinks = []
 var warned_channels = {}
+var log_stack_enabled = false
 
 function log(name, args) {
   var msg = args[0]
@@ -476,15 +477,27 @@ function load_log_config() {
     }
   }
   build_sink_routing()
+  log_stack_enabled = log_config.stack == true
 }
 
 function pretty_format(rec) {
   var aid = text(rec.actor_id, 0, 5)
   var src = ""
+  var ev = null
+  var out = null
+  var i = 0
+  var fr = null
   if (rec.source && rec.source.file)
     src = rec.source.file + ":" + text(rec.source.line)
-  var ev = is_text(rec.event) ? rec.event : json.encode(rec.event, false)
-  return `[${aid}] [${rec.channel}] ${src} ${ev}\n`
+  ev = is_text(rec.event) ? rec.event : json.encode(rec.event, false)
+  out = `[${aid}] [${rec.channel}] ${src} ${ev}\n`
+  if (rec.stack && length(rec.stack) > 0) {
+    for (i = 0; i < length(rec.stack); i = i + 1) {
+      fr = rec.stack[i]
+      out = out + `    at ${fr.fn} (${fr.file}:${text(fr.line)}:${text(fr.col)})\n`
+    }
+  }
+  return out
 }
 
 function bare_format(rec) {
@@ -523,6 +536,9 @@ load_log_config()
 log = function(name, args) {
   var sinks = channel_sinks[name]
   var event = args[0]
+  var caller = null
+  var stack = null
+  var rec = null
 
   if (!sinks && length(wildcard_sinks) == 0) {
     if (!warned_channels[name]) {
@@ -532,14 +548,16 @@ log = function(name, args) {
     return
   }
 
-  var caller = caller_info(2)
-  var rec = {
+  caller = caller_info(2)
+  if (log_stack_enabled) stack = os.stack(1)
+  rec = {
     actor_id: _cell.id,
     timestamp: time.number(),
     channel: name,
     event: event,
     source: caller
   }
+  if (stack) rec.stack = stack
 
   if (sinks) arrfor(sinks, function(sink) { dispatch_to_sink(sink, rec) })
   arrfor(wildcard_sinks, function(sink) { dispatch_to_sink(sink, rec) })

internal/os.c

@@ -674,6 +674,27 @@ static JSValue js_os_embedded_module(JSContext *js, JSValue self, int argc, JSVa
   return js_new_blob_stoned_copy(js, (void *)entry->data, entry->size);
 }
 
+static JSValue js_os_stack(JSContext *js, JSValue self, int argc, JSValue *argv) {
+  (void)self;
+  int skip = 0;
+  if (argc > 0) JS_ToInt32(js, &skip, argv[0]);
+
+  JSValue full = JS_GetStack(js);
+  if (skip <= 0) return full;
+
+  int64_t n = 0;
+  JS_GetLength(js, full, &n);
+  if (skip >= (int)n) return JS_NewArray(js);
+
+  JS_FRAME(js);
+  JS_ROOT(arr, JS_NewArray(js));
+  for (int i = skip; i < (int)n; i++) {
+    JSValue item = JS_GetPropertyNumber(js, full, i);
+    JS_SetPropertyNumber(js, arr.val, i - skip, item);
+  }
+  JS_RETURN(arr.val);
+}
+
 static const JSCFunctionListEntry js_os_funcs[] = {
   MIST_FUNC_DEF(os, platform, 0),
   MIST_FUNC_DEF(os, arch, 0),
@@ -701,6 +722,7 @@ static const JSCFunctionListEntry js_os_funcs[] = {
   MIST_FUNC_DEF(os, random, 0),
   MIST_FUNC_DEF(os, getenv, 1),
   MIST_FUNC_DEF(os, qbe, 1),
+  MIST_FUNC_DEF(os, stack, 1),
 };
 
 JSValue js_core_os_use(JSContext *js) {