Implement safepointing of threads

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 "include/dart_native_api.h"
 #include "platform/assert.h"
 #include "platform/text_buffer.h"
@@ skipping 11 matching lines @@
 #include "vm/lockers.h"
 #include "vm/log.h"
 #include "vm/message_handler.h"
 #include "vm/object_id_ring.h"
 #include "vm/object_store.h"
 #include "vm/object.h"
 #include "vm/os_thread.h"
 #include "vm/port.h"
 #include "vm/profiler.h"
 #include "vm/reusable_handles.h"
+#include "vm/safepoint.h"
 #include "vm/service.h"
 #include "vm/service_event.h"
 #include "vm/service_isolate.h"
 #include "vm/simulator.h"
 #include "vm/stack_frame.h"
 #include "vm/store_buffer.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
 #include "vm/tags.h"
 #include "vm/thread_interrupter.h"
@@ skipping 697 matching lines @@
 Isolate::Isolate(const Dart_IsolateFlags& api_flags)
   :   stack_limit_(0),
       store_buffer_(new StoreBuffer()),
       heap_(NULL),
       user_tag_(0),
       current_tag_(UserTag::null()),
       default_tag_(UserTag::null()),
       class_table_(),
       single_step_(false),
       thread_registry_(new ThreadRegistry()),
+      safepoint_handler_(new SafepointHandler(this)),
       message_notify_callback_(NULL),
       name_(NULL),
       debugger_name_(NULL),
       start_time_(OS::GetCurrentTimeMicros()),
       main_port_(0),
       origin_id_(0),
       pause_capability_(0),
       terminate_capability_(0),
       errors_fatal_(true),
       object_store_(NULL),
@@ skipping 73 matching lines @@
   delete object_id_ring_;
   object_id_ring_ = NULL;
   delete pause_loop_monitor_;
   pause_loop_monitor_ = NULL;
   ASSERT(spawn_count_ == 0);
   delete spawn_count_monitor_;
   if (compiler_stats_ != NULL) {
     delete compiler_stats_;
     compiler_stats_ = NULL;
   }
+  delete safepoint_handler_;
   delete thread_registry_;
 }
 
 
-#if defined(DEBUG)
-bool Isolate::IsIsolateOf(Thread* thread) {
-  return this == thread->isolate();
-}
-#endif  // DEBUG
-
-
 void Isolate::InitOnce() {
   create_callback_ = NULL;
   isolates_list_monitor_ = new Monitor();
   ASSERT(isolates_list_monitor_ != NULL);
   EnableIsolateCreation();
 }
 
 
 Isolate* Isolate::Init(const char* name_prefix,
                        const Dart_IsolateFlags& api_flags,
@@ skipping 587 matching lines @@
   }
   uword interrupt_bits = stack_limit_ & kInterruptsMask;
   stack_limit_ = saved_stack_limit_;
   return interrupt_bits;
 }
 
 
 RawError* Isolate::HandleInterrupts() {
   uword interrupt_bits = GetAndClearInterrupts();
   if ((interrupt_bits & kVMInterrupt) != 0) {
-    thread_registry()->CheckSafepoint();
     if (store_buffer()->Overflowed()) {
       if (FLAG_verbose_gc) {
         OS::PrintErr("Scavenge scheduled by store buffer overflow.\n");
       }
       heap()->CollectGarbage(Heap::kNew);
     }
   }
   if ((interrupt_bits & kMessageInterrupt) != 0) {
     MessageHandler::MessageStatus status =
         message_handler()->HandleOOBMessages();
@@ skipping 288 matching lines @@
       reinterpret_cast<RawObject**>(&registered_service_extension_handlers_));
 
   // Visit objects in the debugger.
   debugger()->VisitObjectPointers(visitor);
 
   // Visit objects that are being used for deoptimization.
   if (deopt_context() != NULL) {
     deopt_context()->VisitObjectPointers(visitor);
   }
 
-  // Visit objects in thread registry (e.g., Dart stack, handles in zones).
+  // Visit objects in all threads (e.g., Dart stack, handles in zones).
   thread_registry()->VisitObjectPointers(visitor, validate_frames);
 }
 
 
 void Isolate::VisitWeakPersistentHandles(HandleVisitor* visitor) {
   if (api_state() != NULL) {
     api_state()->VisitWeakHandles(visitor);
   }
 }
 
 
+void Isolate::PrepareForGC() {
+  thread_registry()->PrepareForGC();
+}
+
+
 static const char* ExceptionPauseInfoToServiceEnum(Dart_ExceptionPauseInfo pi) {
   switch (pi) {
     case kPauseOnAllExceptions:
       return "All";
     case kNoPauseOnExceptions:
       return "None";
     case kPauseOnUnhandledExceptions:
       return "Unhandled";
     default:
       UNIMPLEMENTED();
@@ skipping 537 matching lines @@
 
 
 void Isolate::WaitForOutstandingSpawns() {
   MonitorLocker ml(spawn_count_monitor_);
   while (spawn_count_ > 0) {
     ml.Wait();
   }
 }
 
 
+Monitor* Isolate::threads_lock() const {
+  return thread_registry_->threads_lock();
+}
+
+
+Thread* Isolate::ScheduleThread(bool is_mutator, bool bypass_safepoint) {
+  // Schedule the thread into the isolate by associating
+  // a 'Thread' structure with it (this is done while we are holding
+  // the thread registry lock).
+  Thread* thread = NULL;
+  OSThread* os_thread = OSThread::Current();
+  if (os_thread != NULL) {
+    MonitorLocker ml(threads_lock());
+
+    // If a safepoint operation is in progress wait for it
+    // to finish before scheduling this thread in.
+    while (!bypass_safepoint && safepoint_handler()->safepoint_in_progress()) {
+      ml.Wait();
+    }
+
+    // Now get a free Thread structure.
+    thread = thread_registry()->GetFreeThreadLocked(this, is_mutator);
+    ASSERT(thread != NULL);
+
+    // Set up other values and set the TLS value.
+    thread->isolate_ = this;
+    ASSERT(heap() != NULL);
+    thread->heap_ = heap();
+    thread->set_os_thread(os_thread);
+    ASSERT(thread->execution_state() == Thread::kThreadInVM);
+    thread->set_safepoint_state(0);
+    thread->set_vm_tag(VMTag::kVMTagId);
+    os_thread->set_thread(thread);
+    if (is_mutator) {
+      mutator_thread_ = thread;
+    }
+    Thread::SetCurrent(thread);
+    os_thread->EnableThreadInterrupts();
+  }
+  return thread;
+}
+
+
+void Isolate::UnscheduleThread(Thread* thread,
+                               bool is_mutator,
+                               bool bypass_safepoint) {
+  // Disassociate the 'Thread' structure and unschedule the thread
+  // from this isolate.
+  MonitorLocker ml(threads_lock());
+  if (!bypass_safepoint) {
+    // Ensure that the thread reports itself as being at a safepoint.
+    thread->EnterSafepoint();
+  }
+  OSThread* os_thread = thread->os_thread();
+  ASSERT(os_thread != NULL);
+  os_thread->DisableThreadInterrupts();
+  os_thread->set_thread(NULL);
+  OSThread::SetCurrent(os_thread);
+  if (is_mutator) {
+    mutator_thread_ = NULL;
+  }
+  thread->isolate_ = NULL;
+  thread->heap_ = NULL;
+  thread->set_os_thread(NULL);
+  thread->set_execution_state(Thread::kThreadInVM);
+  thread->set_safepoint_state(0);
+  // Return thread structure.
+  thread_registry()->ReturnThreadLocked(is_mutator, thread);
+}
+
+
 static RawInstance* DeserializeObject(Thread* thread,
                                       uint8_t* obj_data,
                                       intptr_t obj_len) {
   if (obj_data == NULL) {
     return Instance::null();
   }
   MessageSnapshotReader reader(obj_data, obj_len, thread);
   Zone* zone = thread->zone();
   const Object& obj = Object::Handle(zone, reader.ReadObject());
   ASSERT(!obj.IsError());
@@ skipping 211 matching lines @@
 void IsolateSpawnState::DecrementSpawnCount() {
   ASSERT(spawn_count_monitor_ != NULL);
   ASSERT(spawn_count_ != NULL);
   MonitorLocker ml(spawn_count_monitor_);
   ASSERT(*spawn_count_ > 0);
   *spawn_count_ = *spawn_count_ - 1;
   ml.Notify();
 }
 
 }  // namespace dart