clientBase.cxx

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/**
 * PANDA 3D SOFTWARE
 * Copyright (c) Carnegie Mellon University.  All rights reserved.
 *
 * All use of this software is subject to the terms of the revised BSD
 * license.  You should have received a copy of this license along
 * with this source code in a file named "LICENSE."
 *
 * @file clientBase.cxx
 * @author jason
 * @date 2000-08-04
 */

#include "clientBase.h"
#include "config_device.h"

TypeHandle ClientBase::_type_handle;

/**
 *
 */
ClientBase::
ClientBase() {
  _forked = false;
  _last_poll_time = 0.0f;
  _last_poll_frame = 0;
  _cs = CS_default;

#ifdef OLD_HAVE_IPC
  _client_thread = nullptr;
  _shutdown = false;
#endif
}


/**
 *
 */
ClientBase::
~ClientBase() {
  // We have to disconnect all of our devices before destructing.
  Devices::iterator di;
  Devices devices_copy = _devices;
  for (di = devices_copy.begin(); di != devices_copy.end(); ++di) {
    DevicesByName &dbn = (*di).second;
    DevicesByName::iterator dbni;
    for (dbni = dbn.begin(); dbni != dbn.end(); ++dbni) {
      ClientDevice *device = (*dbni).second;
      device->disconnect();
    }
  }

#ifdef OLD_HAVE_IPC
  if (_forked) {
    _shutdown = true;

    // Join the loader thread - calling process blocks until the loader thread
    // returns.
    void *ret;
    _client_thread->join(&ret);
  }
#endif
}

/**
 * Forks a separate thread to do all the polling of connected devices.  The
 * forked thread will poll after every poll_time seconds has elapsed.  Returns
 * true if the fork was successful, or false otherwise (for instance, because
 * we were already forked, or because asynchronous threads are disabled).
 */
bool ClientBase::
fork_asynchronous_thread(double poll_time) {
#ifdef OLD_HAVE_IPC
  if (_forked) {
    device_cat.error()
      << "Attempt to fork client thread twice.\n";
    return false;
  }

  if (asynchronous_clients) {
    _sleep_time = (int)(1000000 * poll_time);

    _client_thread = thread::create(&st_callback, this);
    _forked = true;
    if (device_cat.is_debug()) {
      device_cat.debug()
        << "fork_asynchronous_thread() - forking client thread"
        << std::endl;
    }
    return true;
  }
#endif

  return false;
}

/**
 * Returns a ClientDevice pointer that corresponds to the named device of the
 * indicated device type.  The device_type should be one of
 * ClientTrackerDevice, ClientAnalogDevice, etc.; the device_name is
 * implementation defined.
 *
 * Normally, the user does not need to call this function directly; it is
 * called automatically by creating a TrackerNode or AnalogNode or some such
 * data graph node.
 *
 * The return value is the pointer to the created device (which might be the
 * same pointer returned by a previous call to this function with the same
 * parameters).  When the pointer destructs (i.e.  its reference count reaches
 * zero) it will automatically be disconnected.
 *
 * If the named device does not exist or cannot be connected for some reason,
 * NULL is returned.
 */
PT(ClientDevice) ClientBase::
get_device(TypeHandle device_type, const std::string &device_name) {
  DevicesByName &dbn = _devices[device_type];

  DevicesByName::iterator dbni;
  dbni = dbn.find(device_name);
  if (dbni != dbn.end()) {
    // This device was previously connected.  Return it again.
    return (*dbni).second;
  }

  // We need to create a new device for this name.
  PT(ClientDevice) device = make_device(device_type, device_name);

  if (device != nullptr) {
    dbn.insert(DevicesByName::value_type(device_name, device));
  }

  return device;
}

/**
 * Removes the device, which is presumably about to destruct, from the list of
 * connected devices, and frees any data required to support it.  This device
 * will no longer receive automatic updates with each poll.
 *
 * The return value is true if the device was disconnected, or false if it was
 * unknown (e.g.  it was disconnected previously).
 */
bool ClientBase::
disconnect_device(TypeHandle device_type, const std::string &device_name,
                  ClientDevice *device) {
  DevicesByName &dbn = _devices[device_type];

  DevicesByName::iterator dbni;
  dbni = dbn.find(device_name);
  if (dbni != dbn.end()) {
    if ((*dbni).second == device) {
      // We found it!
      dbn.erase(dbni);
      return true;
    }
  }

  // The device was unknown.
  return false;
}

/**
 * Implements the polling and updating of connected devices, if the ClientBase
 * requires this.  This may be called in a sub-thread if
 * fork_asynchronous_thread() was called; otherwise, it will be called once
 * per frame.
 */
void ClientBase::
do_poll() {
  ClockObject *global_clock = ClockObject::get_global_clock();
  _last_poll_frame = global_clock->get_frame_count();
  _last_poll_time = global_clock->get_frame_time();
}

#ifdef OLD_HAVE_IPC
/**
 * Call back function for thread (if thread has been spawned).  A call back
 * function must be static, so this merely calls the non-static member
 * callback In addition, the function has a void* return type even though we
 * don't actually return anything.  This is necessary because ipc assumes a
 * function that does not return anything indicates that the associated thread
 * should  be created as unjoinable (detached).
 */
void *ClientBase::
st_callback(void *arg) {
  nassertr(arg != nullptr, nullptr);
  ((ClientBase *)arg)->callback();
  return nullptr;
}

/**
 * This is the main body of the sub-thread.  It sleeps a certain time and then
 * polls all devices currently being watched
 */
void ClientBase::
callback() {
  while (true) {
    if (_shutdown) {
      break;
    }
    do_poll();
    ipc_traits::sleep(0, _sleep_time);
  }
}
#endif // OLD_HAVE_IPC