/*

 * Copyright (c) 1997, 2019, 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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 */

#ifndef SHARE_RUNTIME_SAFEPOINT_HPP

#define SHARE_RUNTIME_SAFEPOINT_HPP

#include "memory/allocation.hpp"

#include "runtime/os.hpp"

#include "utilities/ostream.hpp"

//

// Safepoint synchronization

////

// methods to enter/exit a safepoint region. The begin method will roll

// all JavaThreads forward to a safepoint.

//

// JavaThreads must use the ThreadSafepointState abstraction (defined in

// thread.hpp) to indicate that that they are at a safepoint.

//

// The Mutex/Condition variable and ObjectLocker classes calls the enter/

// exit safepoint methods, when a thread is blocked/restarted. Hence, all mutex exter/

// exit points *must* be at a safepoint.

class ThreadSafepointState;

//

// Implements roll-forward to safepoint (safepoint synchronization)

//

class SafepointSynchronize : AllStatic {

 public:

  enum SynchronizeState {

      _synchronizing    = 1,                   // Synchronizing in progress

  };

  // The enums are listed in the order of the tasks when done serially.

  enum SafepointCleanupTasks {

    SAFEPOINT_CLEANUP_DEFLATE_MONITORS,

    SAFEPOINT_CLEANUP_UPDATE_INLINE_CACHES,

    SAFEPOINT_CLEANUP_COMPILATION_POLICY,

    SAFEPOINT_CLEANUP_SYMBOL_TABLE_REHASH,

    SAFEPOINT_CLEANUP_STRING_TABLE_REHASH,

    SAFEPOINT_CLEANUP_CLD_PURGE,

    SAFEPOINT_CLEANUP_SYSTEM_DICTIONARY_RESIZE,

    // Leave this one last.

    SAFEPOINT_CLEANUP_NUM_TASKS

  };

 private:

  // This counter is used for fast versions of jni_Get<Primitive>Field.

  // The counter is incremented ONLY at the beginning and end of each

  static volatile uint64_t _safepoint_counter;

  // Statistics

  static void begin_statistics(int nof_threads, int nof_running);

  static void update_statistics_on_spin_end();

  static void update_statistics_on_sync_end(jlong end_time);

  static void update_statistics_on_cleanup_end(jlong end_time);

  static void end_statistics(jlong end_time);

  static void print_statistics();

  // For debug long safepoint

  static void print_safepoint_timeout(SafepointTimeoutReason timeout_reason);

public:

  static void begin();

  static void end();                    // Start all suspended threads again...

  // Query

  // Exception handling for page polling

  static void handle_polling_page_exception(JavaThread *thread);

  // VM Thread interface for determining safepoint rate

  static long last_non_safepoint_interval() {

    return os::javaTimeMillis() - _end_of_last_safepoint;

  }

  static long end_of_last_safepoint() {

    return _end_of_last_safepoint;

  }

  static bool is_cleanup_needed();

  static void do_cleanup_tasks();

  static void print_stat_on_exit();

  // Assembly support

  // Only used for making sure that no safepoint has happened in

  // JNI_FastGetField. Therefore only the low 32-bits are needed

  // even if this is a 64-bit counter.

  static address safepoint_counter_addr() {

#ifdef VM_LITTLE_ENDIAN

    return (address)&_safepoint_counter;

#else /* BIG */

    // Return pointer to the 32 LSB:

    return (address) (((uint32_t*)(&_safepoint_counter)) + 1);

#endif

  }

};

// Some helper assert macros for safepoint checks.

#define assert_at_safepoint()                                           \

  assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint")

#define assert_at_safepoint_msg(...)                                    \

  assert(SafepointSynchronize::is_at_safepoint(), __VA_ARGS__)

#define assert_not_at_safepoint()                                       \

  assert(!SafepointSynchronize::is_at_safepoint(), "should not be at a safepoint")

#define assert_not_at_safepoint_msg(...)                                \

  assert(!SafepointSynchronize::is_at_safepoint(), __VA_ARGS__)

// State class for a thread suspended at a safepoint

class ThreadSafepointState: public CHeapObj<mtInternal> {

 private:

 public:

  ThreadSafepointState(JavaThread *thread);

  void restart();

  // Query

  JavaThread*  thread() const         { return _thread; }

  JavaThreadState orig_thread_state() const { return _orig_thread_state; }

  // Support for safepoint timeout (debugging)

  void handle_polling_page_exception();

  // debugging

  void print_on(outputStream* st) const;

  void print() const                        { print_on(tty); }

  // Initialize

  static void create(JavaThread *thread);

  static void destroy(JavaThread *thread);

};

#endif // SHARE_RUNTIME_SAFEPOINT_HPP