Add flag to pin and service command to release isolates

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"
@@ skipping 23 matching lines @@
 #include "vm/timer.h"
 #include "vm/visitor.h"
 
 
 namespace dart {
 
 DEFINE_FLAG(bool, report_usage_count, false,
             "Track function usage and report.");
 DEFINE_FLAG(bool, trace_isolates, false,
             "Trace isolate creation and shut down.");
+DEFINE_FLAG(bool, pin_isolates, false,
+            "Stop isolates from being destroyed automatically.");
 
 
 void Isolate::RegisterClass(const Class& cls) {
   class_table()->Register(cls);
   if (object_histogram() != NULL) object_histogram()->RegisterClass(cls);
 }
 
 
 class IsolateMessageHandler : public MessageHandler {
  public:
@@ skipping 221 matching lines @@
 
 
 #define REUSABLE_HANDLE_INITIALIZERS(object)                                   \
   object##_handle_(NULL),
 
 Isolate::Isolate()
     : store_buffer_(),
       message_notify_callback_(NULL),
       name_(NULL),
       start_time_(OS::GetCurrentTimeMicros()),
+      pin_port_(0),
       main_port_(0),
       heap_(NULL),
       object_store_(NULL),
       top_context_(Context::null()),
       top_exit_frame_info_(0),
       init_callback_data_(NULL),
       environment_callback_(NULL),
       library_tag_handler_(NULL),
       api_state_(NULL),
       stub_code_(NULL),
@@ skipping 119 matching lines @@
   ASSERT(state != NULL);
   result->set_api_state(state);
 
   // Initialize stack top and limit in case we are running the isolate in the
   // main thread.
   // TODO(5411455): Need to figure out how to set the stack limit for the
   // main thread.
   result->SetStackLimitFromCurrentTOS(reinterpret_cast<uword>(&result));
   result->set_main_port(PortMap::CreatePort(result->message_handler()));
   result->BuildName(name_prefix);
+  result->CreatePinPort();

[Ivan Posva, 2014/02/27 18:07:16]

How about:
if (FLAG_pin_isolates) {
  result->CreatePinPort();
}

CreatePinPort reads not like a conditional so to the casual reader it means.
Create the pin port no matter what.

[Cutch, 2014/02/27 18:13:48]

Done.

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

[Ivan Posva, 2014/02/27 18:07:16]

See above.

[Cutch, 2014/02/27 18:13:48]

Done.

+    return;
+  }
+  ASSERT(pin_port_ == 0);
+  pin_port_ = PortMap::CreatePort(message_handler());
+  ASSERT(pin_port_ != 0);
+  PortMap::SetLive(pin_port_);
+}
+
+
+void Isolate::ClosePinPort() {
+  if (!FLAG_pin_isolates) {

[Ivan Posva, 2014/02/27 18:07:16]

This is equivalent to the pin_port_ == 0 condition below. Just remove it as we
unconditionally want to close the pin port here.

[Cutch, 2014/02/27 18:13:48]

Done.

+    return;
+  }
+  if (pin_port_ == 0) {
+    // Support multiple calls to close.
+    return;
+  }
+  ASSERT(pin_port_ != 0);
+  bool r = PortMap::ClosePort(pin_port_);
+  ASSERT(r);
+  pin_port_ = 0;
+}
+
+
 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());
 }
@@ skipping 602 matching lines @@
   return func.raw();
 }
 
 
 void IsolateSpawnState::Cleanup() {
   SwitchIsolateScope switch_scope(isolate());
   Dart::ShutdownIsolate();
 }
 
 }  // namespace dart