Add Kernel Isolate

runtime/vm/kernel_isolate.cc

+// Copyright (c) 2016, 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/kernel_isolate.h"
+
+#include "vm/compiler.h"
+#include "vm/dart_api_impl.h"
+#include "vm/dart_entry.h"
+#include "vm/isolate.h"
+#include "vm/lockers.h"
+#include "vm/message.h"
+#include "vm/message_handler.h"
+#include "vm/native_entry.h"
+#include "vm/native_arguments.h"
+#include "vm/object.h"
+#include "vm/object_store.h"
+#include "vm/port.h"
+#include "vm/service.h"
+#include "vm/symbols.h"
+#include "vm/thread_pool.h"
+#include "vm/timeline.h"
+
+namespace dart {
+
+#define Z (T->zone())
+
+DEFINE_FLAG(bool, trace_kernel, false, "Trace Kernel service requests.");
+
+
+const char* KernelIsolate::kName = "kernel-service";
+Dart_IsolateCreateCallback KernelIsolate::create_callback_ = NULL;
+Monitor* KernelIsolate::monitor_ = NULL;
+Isolate* KernelIsolate::isolate_ = NULL;
+bool KernelIsolate::initializing_ = true;
+bool KernelIsolate::shutting_down_ = false;
+Dart_Port KernelIsolate::kernel_port_ = ILLEGAL_PORT;
+
+
+class RunKernelTask : public ThreadPool::Task {
+ public:
+  virtual void Run() {
+    ASSERT(Isolate::Current() == NULL);
+
+#ifndef PRODUCT
+    TimelineDurationScope tds(Timeline::GetVMStream(), "KernelIsolateStartup");
+#endif  // !PRODUCT
+    char* error = NULL;
+    Isolate* isolate = NULL;
+
+    Dart_IsolateCreateCallback create_callback =
+        KernelIsolate::create_callback();
+
+    if (create_callback == NULL) {
+      KernelIsolate::FinishedInitializing();
+      return;
+    }
+
+    Dart_IsolateFlags api_flags;
+    Isolate::FlagsInitialize(&api_flags);
+
+    isolate = reinterpret_cast<Isolate*>(create_callback(
+        KernelIsolate::kName, NULL, NULL, NULL, &api_flags, NULL, &error));
+    if (isolate == NULL) {
+      if (FLAG_trace_kernel) {
+        OS::PrintErr("kernel-service: Isolate creation error: %s\n", error);
+      }
+      KernelIsolate::SetKernelIsolate(NULL);
+      KernelIsolate::FinishedInitializing();
+      KernelIsolate::FinishedExiting();
+      return;
+    }
+
+    bool got_unwind;
+    {
+      ASSERT(Isolate::Current() == NULL);
+      StartIsolateScope start_scope(isolate);
+      got_unwind = RunMain(isolate);
+    }
+
+    if (got_unwind) {
+      ShutdownIsolate(reinterpret_cast<uword>(isolate));
+      return;
+    }
+
+    KernelIsolate::FinishedInitializing();
+
+    // isolate_ was set as side effect of create callback.
+    ASSERT(KernelIsolate::isolate_ == isolate);
+
+    isolate->message_handler()->Run(Dart::thread_pool(), NULL, ShutdownIsolate,
+                                    reinterpret_cast<uword>(isolate));
+  }
+
+ protected:
+  static void ShutdownIsolate(uword parameter) {
+    if (FLAG_trace_kernel) {
+      OS::Print("kernel-service: ShutdownIsolate\n");
+    }
+    Isolate* I = reinterpret_cast<Isolate*>(parameter);
+    ASSERT(KernelIsolate::IsKernelIsolate(I));
+    KernelIsolate::SetKernelIsolate(NULL);
+    KernelIsolate::SetLoadPort(ILLEGAL_PORT);
+    I->WaitForOutstandingSpawns();
+    {
+      // Print the error if there is one.  This may execute dart code to
+      // print the exception object, so we need to use a StartIsolateScope.
+      ASSERT(Isolate::Current() == NULL);
+      StartIsolateScope start_scope(I);
+      Thread* T = Thread::Current();
+      ASSERT(I == T->isolate());
+      StackZone zone(T);
+      HandleScope handle_scope(T);
+      Error& error = Error::Handle(Z);
+      error = T->sticky_error();
+      if (!error.IsNull() && !error.IsUnwindError()) {
+        OS::PrintErr("kernel-service: Error: %s\n", error.ToErrorCString());
+      }
+      error = I->sticky_error();
+      if (!error.IsNull() && !error.IsUnwindError()) {
+        OS::PrintErr("kernel-service: Error: %s\n", error.ToErrorCString());
+      }
+      Dart::RunShutdownCallback();
+    }
+    // Shut the isolate down.
+    Dart::ShutdownIsolate(I);
+    if (FLAG_trace_kernel) {
+      OS::Print("kernel-service: Shutdown.\n");
+    }
+    KernelIsolate::FinishedExiting();
+  }
+
+  bool RunMain(Isolate* I) {
+    Thread* T = Thread::Current();
+    ASSERT(I == T->isolate());
+    StackZone zone(T);
+    HANDLESCOPE(T);
+    // Invoke main which will return the port to which load requests are sent.
+    const Library& root_library =
+        Library::Handle(Z, I->object_store()->root_library());
+    if (root_library.IsNull()) {
+      if (FLAG_trace_kernel) {
+        OS::Print("kernel-service: Embedder did not install a script.");
+      }
+      // Kernel isolate is not supported by embedder.
+      return false;

[siva, 2016/12/02 00:39:23]

This false return is weird here as we will continue and start executing the
message handler Run after this even though the result was an error
and not shutdown the isolate.

+    }
+    ASSERT(!root_library.IsNull());
+    const String& entry_name = String::Handle(Z, String::New("main"));
+    ASSERT(!entry_name.IsNull());
+    const Function& entry = Function::Handle(
+        Z, root_library.LookupFunctionAllowPrivate(entry_name));
+    if (entry.IsNull()) {
+      // Kernel isolate is not supported by embedder.
+      if (FLAG_trace_kernel) {
+        OS::Print("kernel-service: Embedder did not provide a main function.");
+      }
+      return false;

[siva, 2016/12/02 00:39:23]

ditto comment here about the false return.

+    }
+    ASSERT(!entry.IsNull());
+    const Object& result = Object::Handle(
+        Z, DartEntry::InvokeFunction(entry, Object::empty_array()));
+    ASSERT(!result.IsNull());
+    if (result.IsError()) {
+      // Kernel isolate did not initialize properly.
+      if (FLAG_trace_kernel) {
+        const Error& error = Error::Cast(result);
+        OS::Print("kernel-service: Calling main resulted in an error: %s",
+                  error.ToErrorCString());
+      }
+      if (result.IsUnwindError()) {
+        return true;
+      }
+      return false;

[siva, 2016/12/02 00:39:23]

ditto comment here about the false return

+    }
+    ASSERT(result.IsReceivePort());
+    const ReceivePort& rp = ReceivePort::Cast(result);
+    KernelIsolate::SetLoadPort(rp.Id());
+    return false;
+  }
+};
+
+
+void KernelIsolate::Run() {
+  ASSERT(monitor_ == NULL);
+  monitor_ = new Monitor();
+  ASSERT(monitor_ != NULL);
+  // Grab the isolate create callback here to avoid race conditions with tests
+  // that change this after Dart_Initialize returns.
+  create_callback_ = Isolate::CreateCallback();
+  Dart::thread_pool()->Run(new RunKernelTask());
+}
+
+
+void KernelIsolate::InitCallback(Isolate* I) {
+  Thread* T = Thread::Current();
+  ASSERT(I == T->isolate());
+  ASSERT(I != NULL);
+  ASSERT(I->name() != NULL);
+  if (strstr(I->name(), "kernel-service") == NULL) {
+    // Not service isolate.
+    return;
+  }
+  ASSERT(!Exists());
+  if (FLAG_trace_kernel) {
+    OS::Print("kernel-service: InitCallback for %s.\n", I->name());
+  }
+  SetKernelIsolate(I);
+}
+
+
+bool KernelIsolate::IsKernelIsolate(const Isolate* isolate) {
+  MonitorLocker ml(monitor_);
+  return isolate == isolate_;
+}
+
+
+bool KernelIsolate::IsRunning() {
+  MonitorLocker ml(monitor_);
+  return (kernel_port_ != ILLEGAL_PORT) && (isolate_ != NULL);
+}
+
+
+void KernelIsolate::FinishedExiting() {
+  MonitorLocker ml(monitor_);
+  shutting_down_ = false;
+  ml.NotifyAll();
+}
+
+
+bool KernelIsolate::Exists() {
+  MonitorLocker ml(monitor_);
+  return isolate_ != NULL;
+}
+
+
+void KernelIsolate::SetKernelIsolate(Isolate* isolate) {
+  MonitorLocker ml(monitor_);
+  isolate_ = isolate;
+}
+
+void KernelIsolate::SetLoadPort(Dart_Port port) {
+  MonitorLocker ml(monitor_);
+  kernel_port_ = port;
+}
+
+void KernelIsolate::FinishedInitializing() {
+  MonitorLocker ml(monitor_);
+  initializing_ = false;
+  ml.NotifyAll();
+}
+
+
+Dart_Port KernelIsolate::WaitForKernelPort() {
+  MonitorLocker ml(monitor_);
+  while (initializing_ && (kernel_port_ == ILLEGAL_PORT)) {
+    ml.Wait();
+  }
+  return kernel_port_;
+}
+
+}  // namespace dart