8265754: Move suspend/resume API from HandshakeState

Reviewed-by: coleenp, dholmes, pchilanomate

Author: toxaart

src/hotspot/share/runtime/handshake.cpp

@@ -465,9 +465,7 @@ HandshakeState::HandshakeState(JavaThread* target) :
   _queue(),
   _lock(Monitor::nosafepoint, "HandshakeState_lock"),
   _active_handshaker(),
-  _async_exceptions_blocked(false),
-  _suspended(false),
-  _async_suspend_handshake(false) {
+  _async_exceptions_blocked(false) {
 }
 
 HandshakeState::~HandshakeState() {
@@ -699,128 +697,8 @@ HandshakeState::ProcessResult HandshakeState::try_process(HandshakeOperation* ma
   return op == match_op ? HandshakeState::_succeeded : HandshakeState::_processed;
 }
 
-void HandshakeState::do_self_suspend() {
-  assert(Thread::current() == _handshakee, "should call from _handshakee");
-  assert(_lock.owned_by_self(), "Lock must be held");
-  assert(!_handshakee->has_last_Java_frame() || _handshakee->frame_anchor()->walkable(), "should have walkable stack");
-  assert(_handshakee->thread_state() == _thread_blocked, "Caller should have transitioned to _thread_blocked");
-
-  while (is_suspended()) {
-    log_trace(thread, suspend)("JavaThread:" INTPTR_FORMAT " suspended", p2i(_handshakee));
-    _lock.wait_without_safepoint_check();
-  }
-  log_trace(thread, suspend)("JavaThread:" INTPTR_FORMAT " resumed", p2i(_handshakee));
-}
-
-// This is the closure that prevents a suspended JavaThread from
-// escaping the suspend request.
-class ThreadSelfSuspensionHandshake : public AsyncHandshakeClosure {
- public:
-  ThreadSelfSuspensionHandshake() : AsyncHandshakeClosure("ThreadSelfSuspensionHandshake") {}
-  void do_thread(Thread* thr) {
-    JavaThread* current = JavaThread::cast(thr);
-    assert(current == Thread::current(), "Must be self executed.");
-    JavaThreadState jts = current->thread_state();
-
-    current->set_thread_state(_thread_blocked);
-    current->handshake_state()->do_self_suspend();
-    current->set_thread_state(jts);
-    current->handshake_state()->set_async_suspend_handshake(false);
-  }
-  virtual bool is_suspend() { return true; }
-};
-
-bool HandshakeState::suspend_with_handshake(bool register_vthread_SR) {
-  assert(_handshakee->threadObj() != nullptr, "cannot suspend with a null threadObj");
-  if (_handshakee->is_exiting()) {
-    log_trace(thread, suspend)("JavaThread:" INTPTR_FORMAT " exiting", p2i(_handshakee));
-    return false;
-  }
-  if (has_async_suspend_handshake()) {
-    if (is_suspended()) {
-      // Target is already suspended.
-      log_trace(thread, suspend)("JavaThread:" INTPTR_FORMAT " already suspended", p2i(_handshakee));
-      return false;
-    } else {
-      // Target is going to wake up and leave suspension.
-      // Let's just stop the thread from doing that.
-      log_trace(thread, suspend)("JavaThread:" INTPTR_FORMAT " re-suspended", p2i(_handshakee));
-      set_suspended(true, register_vthread_SR);
-      return true;
-    }
-  }
-  // no suspend request
-  assert(!is_suspended(), "cannot be suspended without a suspend request");
-  // Thread is safe, so it must execute the request, thus we can count it as suspended
-  // from this point.
-  set_suspended(true, register_vthread_SR);
-  set_async_suspend_handshake(true);
-  log_trace(thread, suspend)("JavaThread:" INTPTR_FORMAT " suspended, arming ThreadSuspension", p2i(_handshakee));
-  ThreadSelfSuspensionHandshake* ts = new ThreadSelfSuspensionHandshake();
-  Handshake::execute(ts, _handshakee);
-  return true;
-}
-
-// This is the closure that synchronously honors the suspend request.
-class SuspendThreadHandshake : public HandshakeClosure {
-  bool _register_vthread_SR;
-  bool _did_suspend;
-public:
-  SuspendThreadHandshake(bool register_vthread_SR) : HandshakeClosure("SuspendThread"),
-    _register_vthread_SR(register_vthread_SR), _did_suspend(false) {}
-  void do_thread(Thread* thr) {
-    JavaThread* target = JavaThread::cast(thr);
-    _did_suspend = target->handshake_state()->suspend_with_handshake(_register_vthread_SR);
-  }
-  bool did_suspend() { return _did_suspend; }
-};
-
-bool HandshakeState::suspend(bool register_vthread_SR) {
-  JVMTI_ONLY(assert(!_handshakee->is_in_VTMS_transition(), "no suspend allowed in VTMS transition");)
-  JavaThread* self = JavaThread::current();
-  if (_handshakee == self) {
-    // If target is the current thread we can bypass the handshake machinery
-    // and just suspend directly
-    ThreadBlockInVM tbivm(self);
-    MutexLocker ml(&_lock, Mutex::_no_safepoint_check_flag);
-    set_suspended(true, register_vthread_SR);
-    do_self_suspend();
-    return true;
-  } else {
-    SuspendThreadHandshake st(register_vthread_SR);
-    Handshake::execute(&st, _handshakee);
-    return st.did_suspend();
-  }
-}
-
-bool HandshakeState::resume(bool register_vthread_SR) {
-  MutexLocker ml(&_lock, Mutex::_no_safepoint_check_flag);
-  if (!is_suspended()) {
-    assert(!_handshakee->is_suspended(), "cannot be suspended without a suspend request");
-    return false;
-  }
-  // Resume the thread.
-  set_suspended(false, register_vthread_SR);
-  _lock.notify();
-  return true;
-}
-
-void HandshakeState::set_suspended(bool is_suspend, bool register_vthread_SR) {
-#if INCLUDE_JVMTI
-  if (register_vthread_SR) {
-    assert(_handshakee->is_vthread_mounted(), "sanity check");
-    if (is_suspend) {
-      JvmtiVTSuspender::register_vthread_suspend(_handshakee->vthread());
-    } else {
-      JvmtiVTSuspender::register_vthread_resume(_handshakee->vthread());
-    }
-  }
-#endif
-  Atomic::store(&_suspended, is_suspend);
-}
-
 void HandshakeState::handle_unsafe_access_error() {
-  if (is_suspended()) {
+  if (_handshakee->is_suspended()) {
     // A suspend handshake was added to the queue after the
     // unsafe access error. Since the suspender has already
     // considered this JT as suspended and assumes it won't go

src/hotspot/share/runtime/handshake.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2017, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -35,8 +35,6 @@
 class HandshakeOperation;
 class AsyncHandshakeOperation;
 class JavaThread;
-class SuspendThreadHandshake;
-class ThreadSelfSuspensionHandshake;
 class UnsafeAccessErrorHandshake;
 class ThreadsListHandle;
 
@@ -88,8 +86,6 @@ class JvmtiRawMonitor;
 // operation is only done by either VMThread/Handshaker on behalf of the
 // JavaThread or by the target JavaThread itself.
 class HandshakeState {
-  friend ThreadSelfSuspensionHandshake;
-  friend SuspendThreadHandshake;
   friend UnsafeAccessErrorHandshake;
   friend JavaThread;
   // This a back reference to the JavaThread,
@@ -98,7 +94,7 @@ class HandshakeState {
   // The queue containing handshake operations to be performed on _handshakee.
   FilterQueue<HandshakeOperation*> _queue;
   // Provides mutual exclusion to this state and queue. Also used for
-  // JavaThread suspend/resume operations.
+  // JavaThread suspend/resume operations performed by SuspendResumeManager.
   Monitor _lock;
   // Set to the thread executing the handshake operation.
   Thread* volatile _active_handshaker;
@@ -160,31 +156,5 @@ class HandshakeState {
   bool async_exceptions_blocked() { return _async_exceptions_blocked; }
   void set_async_exceptions_blocked(bool b) { _async_exceptions_blocked = b; }
   void handle_unsafe_access_error();
-
-  // Suspend/resume support
- private:
-  // This flag is true when the thread owning this
-  // HandshakeState (the _handshakee) is suspended.
-  volatile bool _suspended;
-  // This flag is true while there is async handshake (trap)
-  // on queue. Since we do only need one, we can reuse it if
-  // thread gets suspended again (after a resume)
-  // and we have not yet processed it.
-  bool _async_suspend_handshake;
-
-  // Called from the suspend handshake.
-  bool suspend_with_handshake(bool register_vthread_SR);
-  // Called from the async handshake (the trap)
-  // to stop a thread from continuing execution when suspended.
-  void do_self_suspend();
-
-  bool is_suspended()                       { return Atomic::load(&_suspended); }
-  void set_suspended(bool to, bool register_vthread_SR);
-  bool has_async_suspend_handshake()        { return _async_suspend_handshake; }
-  void set_async_suspend_handshake(bool to) { _async_suspend_handshake = to; }
-
-  bool suspend(bool register_vthread_SR);
-  bool resume(bool register_vthread_SR);
 };
-
 #endif // SHARE_RUNTIME_HANDSHAKE_HPP

src/hotspot/share/runtime/javaThread.cpp

@@ -498,6 +498,7 @@ JavaThread::JavaThread(MemTag mem_tag) :
   _pending_interrupted_exception(false),
 
   _handshake(this),
+  _suspend_resume_manager(this, &_handshake._lock),
 
   _popframe_preserved_args(nullptr),
   _popframe_preserved_args_size(0),
@@ -1200,13 +1201,13 @@ bool JavaThread::java_suspend(bool register_vthread_SR) {
 
   guarantee(Thread::is_JavaThread_protected(/* target */ this),
             "target JavaThread is not protected in calling context.");
-  return this->handshake_state()->suspend(register_vthread_SR);
+  return this->suspend_resume_manager()->suspend(register_vthread_SR);
 }
 
 bool JavaThread::java_resume(bool register_vthread_SR) {
   guarantee(Thread::is_JavaThread_protected_by_TLH(/* target */ this),
             "missing ThreadsListHandle in calling context.");
-  return this->handshake_state()->resume(register_vthread_SR);
+  return this->suspend_resume_manager()->resume(register_vthread_SR);
 }
 
 // Wait for another thread to perform object reallocation and relocking on behalf of

src/hotspot/share/runtime/javaThread.hpp

@@ -40,6 +40,7 @@
 #include "runtime/safepointMechanism.hpp"
 #include "runtime/stackWatermarkSet.hpp"
 #include "runtime/stackOverflow.hpp"
+#include "runtime/suspendResumeManager.hpp"
 #include "runtime/thread.hpp"
 #include "runtime/threadHeapSampler.hpp"
 #include "runtime/threadIdentifier.hpp"
@@ -694,9 +695,13 @@ class JavaThread: public Thread {
 
   // Suspend/resume support for JavaThread
   // higher-level suspension/resume logic called by the public APIs
+private:
+  SuspendResumeManager _suspend_resume_manager;
+public:
   bool java_suspend(bool register_vthread_SR);
   bool java_resume(bool register_vthread_SR);
-  bool is_suspended()     { return _handshake.is_suspended(); }
+  bool is_suspended()     { return _suspend_resume_manager.is_suspended(); }
+  SuspendResumeManager* suspend_resume_manager() { return &_suspend_resume_manager; }
 
   // Check for async exception in addition to safepoint.
   static void check_special_condition_for_native_trans(JavaThread *thread);