Give isolates names to be used during debugging.

runtime/vm/isolate.cc

Index: runtime/vm/isolate.cc
===================================================================
--- runtime/vm/isolate.cc	(revision 3366)
+++ runtime/vm/isolate.cc	(working copy)
@@ -28,7 +28,9 @@
 namespace dart {
 
 DEFINE_FLAG(bool, report_invocation_count, false,
-    "Count function invocations and report.");
+            "Count function invocations and report.");
+DEFINE_FLAG(bool, trace_isolates, false,
+            "Trace isolate creation and shut down.");
 DECLARE_FLAG(bool, generate_gdb_symbols);
 
 
@@ -37,6 +39,7 @@
       message_queue_(NULL),
       post_message_callback_(NULL),
       close_port_callback_(NULL),
+      name_(NULL),
       num_ports_(0),
       live_ports_(0),
       main_port_(0),
@@ -69,6 +72,7 @@
 
 
 Isolate::~Isolate() {
+  delete [] name_;
   delete message_queue_;
   delete heap_;
   delete object_store_;
@@ -107,7 +111,7 @@
 }
 
 
-Isolate* Isolate::Init() {
+Isolate* Isolate::Init(const char* name_prefix) {
   Isolate* result = new Isolate();
   ASSERT(result != NULL);
 
@@ -133,14 +137,35 @@
   // main thread.
   result->SetStackLimitFromCurrentTOS(reinterpret_cast<uword>(&result));
   result->set_main_port(PortMap::CreatePort());
+  result->BuildName(name_prefix);

[siva, 2012/01/18 06:26:03]

Should the name be built only if tracing is enabled?

[turnidge, 2012/01/18 21:29:21]

I plan to also use it when reporting top-level uncaught exceptions and the like.

[siva, 2012/01/18 22:06:08]

Can this be done lazily when it is actually needed?
It would be nice to keep isolate creation and init times low in order to have
fast startup times.

On 2012/01/18 21:29:21, turnidge wrote:

[turnidge, 2012/01/26 18:07:11]

Well, the information being passed to this function, the name prefix, is
somewhat ephemeral.  I can't rely on it living past this function call.  So I
would have to copy it in any case, right?

On 2012/01/18 22:06:08, asiva wrote:

 
   result->debugger_ = new Debugger();
   result->debugger_->Initialize(result);
-
+  if (FLAG_trace_isolates) {
+    if (strcmp(name_prefix, "vm-isolate") != 0) {
+      OS::Print("[+] Starting isolate:\n"
+                "\tisolate:    %s\n", result->name());
+    }
+  }
   return result;
 }
 
 
+void Isolate::BuildName(const char* name_prefix) {
+  if (name_) {
+    delete [] name_;
+    name_ = NULL;
+  }

[siva, 2012/01/18 06:26:03]

Under what circumstances would name_ be non null over here?

[turnidge, 2012/01/18 21:29:21]

It can't happen.  It used to happen in an earlier version of my change. 
Changing this to an ASSERT.

+  if (name_prefix == NULL) {
+    name_prefix = "isolate";
+  }
+  const char* kFormat = "%s-%lld";

[siva, 2012/01/18 06:26:03]

Maybe add a TODO here that generation issues in the name will be addressed
later.

[turnidge, 2012/01/18 21:29:21]

What generation issues?

[siva, 2012/01/18 22:06:08]

i.e if an isolate dies and another isolate is created and it happens to get the
same main port number. In the trace the name would be same but it is actually a
new isolate.

On 2012/01/18 21:29:21, turnidge wrote:

[turnidge, 2012/01/26 18:07:11]

I do not believe that we reuse port numbers currently.

On 2012/01/18 22:06:08, asiva wrote:

+  intptr_t len = OS::SNPrint(NULL, 0, kFormat, name_prefix, main_port()) + 1;
+  name_ = new char[len];
+  OS::SNPrint(name_, len, kFormat, name_prefix, main_port());
+}
+
+
 // TODO(5411455): Use flag to override default value and Validate the
 // stack size by querying OS.
 uword Isolate::GetSpecifiedStackSize() {
@@ -256,7 +281,10 @@
   if (FLAG_generate_gdb_symbols) {
     DebugInfo::UnregisterAllSections();
   }
-
+  if (FLAG_trace_isolates) {
+    OS::Print("[-] Stopping isolate:\n"
+              "\tisolate:    %s\n", name());
+  }
   // TODO(5411455): For now just make sure there are no current isolates
   // as we are shutting down the isolate.
   SetCurrent(NULL);