/*

 * Copyright (c) 2005, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#ifndef SHARE_SERVICES_ATTACHLISTENER_HPP

#define SHARE_SERVICES_ATTACHLISTENER_HPP

#include "memory/allocation.hpp"

#include "metaprogramming/isRegisteredEnum.hpp"

#include "runtime/atomic.hpp"

#include "utilities/debug.hpp"

#include "utilities/globalDefinitions.hpp"

#include "utilities/macros.hpp"

#include "utilities/ostream.hpp"

// The AttachListener thread services a queue of operations that are enqueued

// by client tools. Each operation is identified by a name and has up to 3

// arguments. The operation name is mapped to a function which performs the

// operation. The function is called with an outputStream which is can use to

// write any result data (for examples the properties command serializes

// properties names and values to the output stream). When the function

// complets the result value and any result data is returned to the client

// tool.

class AttachOperation;

typedef jint (*AttachOperationFunction)(AttachOperation* op, outputStream* out);

struct AttachOperationFunctionInfo {

  const char* name;

  AttachOperationFunction func;

};

enum AttachListenerState {

  AL_NOT_INITIALIZED,

  AL_INITIALIZING,

  AL_INITIALIZED

};

template<> struct IsRegisteredEnum<AttachListenerState> : public TrueType {};

class AttachListener: AllStatic {

 public:

  static void vm_start() NOT_SERVICES_RETURN;

  static void init()  NOT_SERVICES_RETURN;

  static void abort() NOT_SERVICES_RETURN;

  // invoke to perform clean-up tasks when all clients detach

  static void detachall() NOT_SERVICES_RETURN;

  // check unix domain socket file on filesystem

  static bool check_socket_file() NOT_SERVICES_RETURN_(false);

  // indicates if the Attach Listener needs to be created at startup

  static bool init_at_startup() NOT_SERVICES_RETURN_(false);

  // indicates if we have a trigger to start the Attach Listener

  static bool is_init_trigger() NOT_SERVICES_RETURN_(false);

#if !INCLUDE_SERVICES

  static bool is_attach_supported()             { return false; }

#else

 private:

  static volatile AttachListenerState _state;

 public:

  static void set_state(AttachListenerState new_state) {

    Atomic::store(&_state, new_state);

  }

  static AttachListenerState get_state() {

    return Atomic::load(&_state);

  }

  static AttachListenerState transit_state(AttachListenerState new_state,

                                           AttachListenerState cmp_state) {

  }

  static bool is_initialized() {

    return Atomic::load(&_state) == AL_INITIALIZED;

  }

  static void set_initialized() {

    Atomic::store(&_state, AL_INITIALIZED);

  }

  // indicates if this VM supports attach-on-demand

  static bool is_attach_supported()             { return !DisableAttachMechanism; }

  // platform specific initialization

  static int pd_init();

  // platform specific operation

  static AttachOperationFunctionInfo* pd_find_operation(const char* name);

  // platform specific flag change

  static jint pd_set_flag(AttachOperation* op, outputStream* out);

  // platform specific detachall

  static void pd_detachall();

  // platform specific data dump

  static void pd_data_dump();

  // dequeue the next operation

  static AttachOperation* dequeue();

#endif // !INCLUDE_SERVICES

 private:

  static bool has_init_error(TRAPS);

};

#if INCLUDE_SERVICES

class AttachOperation: public CHeapObj<mtInternal> {

 public:

  enum {

    name_length_max = 16,       // maximum length of  name

    arg_length_max = 1024,      // maximum length of argument

    arg_count_max = 3           // maximum number of arguments

  };

  // name of special operation that can be enqueued when all

  // clients detach

  static char* detachall_operation_name() { return (char*)"detachall"; }

 private:

  char _name[name_length_max+1];

  char _arg[arg_count_max][arg_length_max+1];

 public:

  const char* name() const                      { return _name; }

  // set the operation name

  void set_name(const char* name) {

    assert(strlen(name) <= name_length_max, "exceeds maximum name length");

    size_t len = MIN2(strlen(name), (size_t)name_length_max);

    memcpy(_name, name, len);

    _name[len] = '\0';

  }

  // get an argument value

  const char* arg(int i) const {

    assert(i>=0 && i<arg_count_max, "invalid argument index");

    return _arg[i];

  }

  // set an argument value

  void set_arg(int i, char* arg) {

    assert(i>=0 && i<arg_count_max, "invalid argument index");

    if (arg == NULL) {

      _arg[i][0] = '\0';

    } else {

      assert(strlen(arg) <= arg_length_max, "exceeds maximum argument length");

      size_t len = MIN2(strlen(arg), (size_t)arg_length_max);

      memcpy(_arg[i], arg, len);

      _arg[i][len] = '\0';

    }

  }

  // create an operation of a given name

  AttachOperation(const char* name) {

    set_name(name);

    for (int i=0; i<arg_count_max; i++) {

      set_arg(i, NULL);

    }

  }

  // complete operation by sending result code and any result data to the client

  virtual void complete(jint result, bufferedStream* result_stream) = 0;

};

#endif // INCLUDE_SERVICES

#endif // SHARE_SERVICES_ATTACHLISTENER_HPP