Introduce API to temporarily interrupt long running JavaScript code.

src/execution.cc

Index: src/execution.cc
diff --git a/src/execution.cc b/src/execution.cc
index c0e9a64fbb000fe94d8a3a0be97c20277ab935e6..634c83ae189e5a2e5cdc8be4abbb0c91f85dcb07 100644
--- a/src/execution.cc
+++ b/src/execution.cc
@@ -540,6 +540,48 @@ void StackGuard::Continue(InterruptFlag after_what) {
 }
 
 
+void StackGuard::RequestInterrupt(InterruptCallback callback, void* data) {
+  ExecutionAccess access(isolate_);
+  thread_local_.interrupt_flags_ |= API_INTERRUPT;
+  thread_local_.interrupt_callback_ = callback;
+  thread_local_.interrupt_callback_data_ = data;
+  set_interrupt_limits(access);
+}
+
+
+void StackGuard::ClearInterrupt() {
+  thread_local_.interrupt_callback_ = 0;
+  thread_local_.interrupt_callback_data_ = 0;
+  Continue(API_INTERRUPT);
+}
+
+
+bool StackGuard::IsAPIInterrupt() {
+  ExecutionAccess access(isolate_);
+  return thread_local_.interrupt_flags_ & API_INTERRUPT;
+}
+
+
+void StackGuard::InvokeInterruptCallback() {
+  InterruptCallback callback = 0;
+  void* data = 0;
+
+  {
+    ExecutionAccess access(isolate_);
+    callback = thread_local_.interrupt_callback_;
+    data = thread_local_.interrupt_callback_data_;
+    thread_local_.interrupt_callback_ = NULL;
+    thread_local_.interrupt_callback_data_ = NULL;
+  }
+
+  if (callback != NULL) {
+    VMState<EXTERNAL> state(isolate_);
+    HandleScope handle_scope(isolate_);
+    callback(reinterpret_cast<v8::Isolate*>(isolate_), data);
+  }
+}
+
+
 char* StackGuard::ArchiveStackGuard(char* to) {
   ExecutionAccess access(isolate_);
   OS::MemCopy(to, reinterpret_cast<char*>(&thread_local_), sizeof(ThreadLocal));
@@ -581,6 +623,7 @@ void StackGuard::ThreadLocal::Clear() {
   nesting_ = 0;
   postpone_interrupts_nesting_ = 0;
   interrupt_flags_ = 0;
+  interrupt_callback_ = 0;
 }
 
 
@@ -601,6 +644,7 @@ bool StackGuard::ThreadLocal::Initialize(Isolate* isolate) {
   nesting_ = 0;
   postpone_interrupts_nesting_ = 0;
   interrupt_flags_ = 0;
+  interrupt_callback_ = 0;
   return should_set_stack_limits;
 }
 
@@ -936,6 +980,11 @@ MaybeObject* Execution::HandleStackGuardInterrupt(Isolate* isolate) {
     return isolate->heap()->undefined_value();
   }
 
+  if (stack_guard->IsAPIInterrupt()) {
+    stack_guard->InvokeInterruptCallback();
+    stack_guard->Continue(API_INTERRUPT);
+  }
+
   if (stack_guard->IsGCRequest()) {
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "StackGuard GC request");