/*

 * Copyright (c) 2018, 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.

 *

 */

#include "precompiled.hpp"

#include "logging/log.hpp"

#include "jfr/jfrEvents.hpp"

#include "jfr/metadata/jfrSerializer.hpp"

#include "jfr/periodic/jfrNetworkUtilization.hpp"

#include "jfr/periodic/jfrOSInterface.hpp"

#include "jfr/utilities/jfrTime.hpp"

#include "jfr/utilities/jfrTypes.hpp"

#include "runtime/os_perf.hpp"

#include "utilities/globalDefinitions.hpp"

#include "utilities/growableArray.hpp"

struct InterfaceEntry {

  char* name;

  traceid id;

  uint64_t bytes_in;

  uint64_t bytes_out;

  bool in_use;

};

static GrowableArray<InterfaceEntry>* _interfaces = NULL;

void JfrNetworkUtilization::destroy() {

  if (_interfaces != NULL) {

    for (int i = 0; i < _interfaces->length(); ++i) {

      FREE_C_HEAP_ARRAY(char, _interfaces->at(i).name);

    }

    delete _interfaces;

    _interfaces = NULL;

  }

}

static InterfaceEntry& new_entry(const NetworkInterface* iface, GrowableArray<InterfaceEntry>* interfaces) {

  assert(iface != NULL, "invariant");

  assert(interfaces != NULL, "invariant");

  // single threaded premise

  static traceid interface_id = 0;

  const char* name = iface->get_name();

  assert(name != NULL, "invariant");

  InterfaceEntry entry;

  const size_t length = strlen(name);

  entry.name = NEW_C_HEAP_ARRAY(char, length + 1, mtInternal);

  strncpy(entry.name, name, length + 1);

  entry.id = ++interface_id;

  entry.bytes_in = iface->get_bytes_in();

  entry.bytes_out = iface->get_bytes_out();

  entry.in_use = false;

  return _interfaces->at(_interfaces->append(entry));

}

static GrowableArray<InterfaceEntry>* get_interfaces() {

  if (_interfaces == NULL) {

    _interfaces = new(ResourceObj::C_HEAP, mtTracing) GrowableArray<InterfaceEntry>(10, true, mtTracing);

  }

  return _interfaces;

}

static InterfaceEntry& get_entry(const NetworkInterface* iface) {

  // Remember the index we started at last time, since we're most likely looking at them

  // in the same order every time.

  static int saved_index = -1;

  GrowableArray<InterfaceEntry>* interfaces = get_interfaces();

  assert(interfaces != NULL, "invariant");

  for (int i = 0; i < _interfaces->length(); ++i) {

    saved_index = (saved_index + 1) % _interfaces->length();

    if (strcmp(_interfaces->at(saved_index).name, iface->get_name()) == 0) {

      return _interfaces->at(saved_index);

    }

  }

  return new_entry(iface, interfaces);

}

// If current counters are less than previous we assume the interface has been reset

// If no bytes have been either sent or received, we'll also skip the event

static uint64_t rate_per_second(uint64_t current, uint64_t old, const JfrTickspan& interval) {

  assert(interval.value() > 0, "invariant");

  if (current <= old) {

    return 0;

  }

  return ((current - old) * NANOSECS_PER_SEC) / interval.nanoseconds();

}

static bool get_interfaces(NetworkInterface** network_interfaces) {

  const int ret_val = JfrOSInterface::network_utilization(network_interfaces);

  if (ret_val == OS_ERR) {

    log_debug(jfr, system)("Unable to generate network utilization events");

    return false;

  }

  return ret_val != FUNCTIONALITY_NOT_IMPLEMENTED;

}

class JfrNetworkInterfaceName : public JfrSerializer {

 public:

  void serialize(JfrCheckpointWriter& writer) {

    assert(_interfaces != NULL, "invariant");

    const JfrCheckpointContext ctx = writer.context();

    const intptr_t count_offset = writer.reserve(sizeof(u4)); // Don't know how many yet

    int active_interfaces = 0;

    for (int i = 0; i < _interfaces->length(); ++i) {

      InterfaceEntry& entry = _interfaces->at(i);

      if (entry.in_use) {

        entry.in_use = false;

        writer.write_key(entry.id);

        writer.write(entry.name);

        ++active_interfaces;

      }

    }

    if (active_interfaces == 0) {

      // nothing to write, restore context

      writer.set_context(ctx);

      return;

    }

    writer.write_count(active_interfaces, count_offset);

  }

};

static bool register_network_interface_name_serializer() {

  assert(_interfaces != NULL, "invariant");

  return JfrSerializer::register_serializer(TYPE_NETWORKINTERFACENAME,

                                            false, // require safepoint

                                            false, // disallow caching; we want a callback every rotation

                                            new JfrNetworkInterfaceName());

}

void JfrNetworkUtilization::send_events() {

  ResourceMark rm;

  NetworkInterface* network_interfaces;

  if (!get_interfaces(&network_interfaces)) {

    return;

  }

  log_trace(jfr, event)("Reporting network utilization");

  static JfrTicks last_sample_instant;

  const JfrTicks cur_time = JfrTicks::now();

  const JfrTickspan interval = last_sample_instant == 0 ? cur_time - cur_time : cur_time - last_sample_instant;

  last_sample_instant = cur_time;

  for (NetworkInterface *cur = network_interfaces; cur != NULL; cur = cur->next()) {

    InterfaceEntry& entry = get_entry(cur);

    if (interval.value() > 0) {

      const uint64_t current_bytes_in = cur->get_bytes_in();

      const uint64_t current_bytes_out = cur->get_bytes_out();

      const uint64_t read_rate = rate_per_second(current_bytes_in, entry.bytes_in, interval);

      const uint64_t write_rate = rate_per_second(current_bytes_out, entry.bytes_out, interval);

      if (read_rate > 0 || write_rate > 0) {

        entry.in_use = true;

        EventNetworkUtilization event(UNTIMED);

        event.set_starttime(cur_time);

        event.set_endtime(cur_time);

        event.set_networkInterface(entry.id);

        event.commit();

      }

      // update existing entry with new values

      entry.bytes_in = current_bytes_in;

      entry.bytes_out = current_bytes_out;

    }

  }

  static bool is_serializer_registered = false;

  if (!is_serializer_registered) {

    is_serializer_registered = register_network_interface_name_serializer();

  }

}