src/hotspot/share/jfr/utilities/jfrThreadIterator.cpp

/*
 * Copyright (c) 2019, 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
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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#include "jfr/support/jfrThreadLocal.hpp"
#include "jfr/utilities/jfrThreadIterator.hpp"
#include "runtime/javaThread.inline.hpp"
#include "runtime/threadSMR.inline.hpp"

static bool thread_inclusion_predicate(Thread* t) {
  assert(t != nullptr, "invariant");
  return !t->jfr_thread_local()->is_dead();
}

static bool java_thread_inclusion_predicate(JavaThread* jt, bool live_only) {
  assert(jt != nullptr, "invariant");
  if (live_only && jt->thread_state() == _thread_new) {
    return false;
  }
  if (jt->is_attaching_via_jni()) {
    return false;
  }
  return thread_inclusion_predicate(jt);
}

static NonJavaThread* next_non_java_thread(NonJavaThread::Iterator& iter) {
  while (!iter.end()) {
    NonJavaThread* next = iter.current();
    iter.step();
    assert(next != nullptr, "invariant");
    if (thread_inclusion_predicate(next)) {
      return next;
    }
  }
  return nullptr;
}

JfrJavaThreadIteratorAdapter::JfrJavaThreadIteratorAdapter(bool live_only /* true */) :
  _tlist(),
  _it(_tlist.begin()),
  _end(_tlist.end()),
  _live_only(live_only)
{
  skip_excluded();
}

bool JfrJavaThreadIteratorAdapter::has_next() const {
  return _it != _end;
}

void JfrJavaThreadIteratorAdapter::skip_excluded() {
  while (has_next() && !java_thread_inclusion_predicate(*_it, _live_only)) {
    ++_it;
  }
}

JavaThread* JfrJavaThreadIteratorAdapter::next() {
  assert(has_next(), "invariant");
  Type* const temp = *_it++;
  skip_excluded();
  return temp;
}

JfrNonJavaThreadIteratorAdapter::JfrNonJavaThreadIteratorAdapter(bool live_only /* true */) : _iter(), _next(next_non_java_thread(_iter)) {}

bool JfrNonJavaThreadIteratorAdapter::has_next() const {
  return _next != nullptr;
}

NonJavaThread* JfrNonJavaThreadIteratorAdapter::next() {
  assert(has_next(), "invariant");
  Type* const temp = _next;
  _next = next_non_java_thread(_iter);
  assert(temp != _next, "invariant");
  return temp;
}

// explicit instantiations
template class JfrThreadIterator<JfrJavaThreadIteratorAdapter, StackObj>;
template class JfrThreadIterator<JfrNonJavaThreadIteratorAdapter, StackObj>;