fix thread state transition in harness (#157)

Use `ThreadInVMfromNative` for thread state transition.

Author: tianleq

mmtk/src/api.rs

@@ -195,22 +195,29 @@ pub extern "C" fn add_phantom_candidate(reff: ObjectReference) {
 
 // The harness_begin()/end() functions are different than other API functions in terms of the thread state.
 // Other functions are called by the VM, thus the thread should already be in the VM state. But the harness
-// functions are called by the probe, and the thread is in JNI/application/native state. Thus we need an extra call
-// to switch the thread state (enter_vm/leave_vm)
+// functions are called by the probe, and the thread is in JNI/application/native state. Thus we need call
+// into VM to switch the thread state and VM will then call into mmtk-core again to do the actual work of
+// harness_begin() and harness_end()
 
 #[no_mangle]
 pub extern "C" fn harness_begin(_id: usize) {
-    let state = unsafe { ((*UPCALLS).enter_vm)() };
+    unsafe { ((*UPCALLS).harness_begin)() };
+}
+
+#[no_mangle]
+pub extern "C" fn mmtk_harness_begin_impl() {
     // Pass null as tls, OpenJDK binding does not rely on the tls value to block the current thread and do a GC
     memory_manager::harness_begin(&SINGLETON, VMMutatorThread(VMThread::UNINITIALIZED));
-    unsafe { ((*UPCALLS).leave_vm)(state) };
 }
 
 #[no_mangle]
 pub extern "C" fn harness_end(_id: usize) {
-    let state = unsafe { ((*UPCALLS).enter_vm)() };
+    unsafe { ((*UPCALLS).harness_end)() };
+}
+
+#[no_mangle]
+pub extern "C" fn mmtk_harness_end_impl() {
     memory_manager::harness_end(&SINGLETON);
-    unsafe { ((*UPCALLS).leave_vm)(state) };
 }
 
 #[no_mangle]

mmtk/src/lib.rs

@@ -52,8 +52,8 @@ pub struct OpenJDK_Upcalls {
     pub get_object_size: extern "C" fn(object: ObjectReference) -> usize,
     pub get_mmtk_mutator: extern "C" fn(tls: VMMutatorThread) -> *mut Mutator<OpenJDK>,
     pub is_mutator: extern "C" fn(tls: VMThread) -> bool,
-    pub enter_vm: extern "C" fn() -> i32,
-    pub leave_vm: extern "C" fn(st: i32),
+    pub harness_begin: extern "C" fn(),
+    pub harness_end: extern "C" fn(),
     pub compute_klass_mem_layout_checksum: extern "C" fn() -> usize,
     pub offset_of_static_fields: extern "C" fn() -> i32,
     pub static_oop_field_count_offset: extern "C" fn() -> i32,

openjdk/CompileThirdPartyHeap.gmk

@@ -7,7 +7,7 @@ MMTK_RUST_ROOT = $(THIRD_PARTY_HEAP)/../mmtk
 MMTK_CPP_ROOT = $(THIRD_PARTY_HEAP)
 
 # Grab OpenJDK version specified in mmtk/Cargo.toml and local OpenJDK version
-OPENJDK_VERSION=`cd $(MMTK_RUST_ROOT) ; cargo read-manifest --manifest-path=Cargo.toml | python -c 'import json,sys; print(json.load(sys.stdin)["metadata"]["openjdk"]["openjdk_version"])'`
+OPENJDK_VERSION=`cd $(MMTK_RUST_ROOT) ; cargo read-manifest --manifest-path=Cargo.toml | python3 -c 'import json,sys; print(json.load(sys.stdin)["metadata"]["openjdk"]["openjdk_version"])'`
 OPENJDK_LOCAL_VERSION=`git rev-parse HEAD`
 
 ifdef MMTK_PLAN

openjdk/mmtk.h

@@ -119,8 +119,8 @@ typedef struct {
     size_t (*get_object_size) (void* object);
     void* (*get_mmtk_mutator) (void* tls);
     bool (*is_mutator) (void* tls);
-    int (*enter_vm) ();
-    void (*leave_vm) (int st);
+    void (*harness_begin) ();
+    void (*harness_end) ();
     size_t (*compute_klass_mem_layout_checksum) ();
     int (*offset_of_static_fields) ();
     int (*static_oop_field_count_offset) ();
@@ -169,8 +169,8 @@ extern void add_weak_candidate(void* ref, void* referent);
 extern void add_soft_candidate(void* ref, void* referent);
 extern void add_phantom_candidate(void* ref, void* referent);
 
-extern void harness_begin(void *tls);
-extern void harness_end();
+extern void mmtk_harness_begin_impl();
+extern void mmtk_harness_end_impl();
 
 #ifdef __cplusplus
 }

openjdk/mmtkUpcalls.cpp

@@ -243,21 +243,21 @@ static size_t mmtk_get_object_size(void* object) {
   return klass->oop_size(o) << LogHeapWordSize;
 }
 
-static int mmtk_enter_vm() {
+static void mmtk_harness_begin() {
   assert(Thread::current()->is_Java_thread(), "Only Java thread can enter vm");
 
   JavaThread* current = ((JavaThread*) Thread::current());
-  JavaThreadState state = current->thread_state();
-  current->set_thread_state(_thread_in_vm);
-  return (int)state;
+  ThreadInVMfromNative tiv(current);
+  mmtk_harness_begin_impl();
+  
 }
 
-static void mmtk_leave_vm(int st) {
+static void mmtk_harness_end() {
   assert(Thread::current()->is_Java_thread(), "Only Java thread can leave vm");
 
   JavaThread* current = ((JavaThread*) Thread::current());
-  assert(current->thread_state() == _thread_in_vm, "Cannot leave vm when the current thread is not in _thread_in_vm");
-  current->set_thread_state((JavaThreadState)st);
+  ThreadInVMfromNative tiv(current);
+  mmtk_harness_end_impl();
 }
 
 static int offset_of_static_fields() {
@@ -356,8 +356,8 @@ OpenJDK_Upcalls mmtk_upcalls = {
   mmtk_get_object_size,
   mmtk_get_mmtk_mutator,
   mmtk_is_mutator,
-  mmtk_enter_vm,
-  mmtk_leave_vm,
+  mmtk_harness_begin,
+  mmtk_harness_end,
   compute_klass_mem_layout_checksum,
   offset_of_static_fields,
   static_oop_field_count_offset,