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 +137,32 @@
   // main thread.
   result->SetStackLimitFromCurrentTOS(reinterpret_cast<uword>(&result));
   result->set_main_port(PortMap::CreatePort());
+  result->BuildName(name_prefix);
 
   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) {
+  ASSERT(name_ == NULL);
+  if (name_prefix == NULL) {
+    name_prefix = "isolate";
+  }
+  const char* kFormat = "%s-%lld";
+  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 +278,10 @@
   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);