/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */


#include "ngx_message_handler.h"

#include <signal.h>

#include "net/instaweb/public/version.h"
#include "pagespeed/kernel/base/abstract_mutex.h"
#include "pagespeed/kernel/base/debug.h"
#include "pagespeed/kernel/base/posix_timer.h"
#include "pagespeed/kernel/base/string_util.h"
#include "pagespeed/kernel/base/time_util.h"
#include "pagespeed/kernel/sharedmem/shared_circular_buffer.h"

namespace {

// This will be prefixed to every logged message.
const char kModuleName[] = "ngx_pagespeed";

// If set, the crash handler will use this to output a backtrace using
// ngx_log_error.
ngx_log_t* global_log = NULL;

}  // namespace

extern "C" {
  static void signal_handler(int sig) {
    // Try to output the backtrace to the log file. Since this may end up
    // crashing/deadlocking/etc. we set an alarm() to abort us if it comes to
    // that.
    alarm(2);
    if (global_log != NULL) {
      ngx_log_error(NGX_LOG_ALERT, global_log, 0, "Trapped signal [%d]\n%s",
                    sig, net_instaweb::StackTraceString().c_str());
    } else {
      fprintf(stderr, "Trapped signal [%d]\n%s\n",
              sig, net_instaweb::StackTraceString().c_str());
    }
    kill(getpid(), SIGKILL);
  }
}  // extern "C"

namespace net_instaweb {

NgxMessageHandler::NgxMessageHandler(Timer* timer, AbstractMutex* mutex)
    : SystemMessageHandler(timer, mutex),
      log_(NULL) {
}

// Installs a signal handler for common crash signals, that tries to print
// out a backtrace.
void NgxMessageHandler::InstallCrashHandler(ngx_log_t* log) {
  global_log = log;
  signal(SIGTRAP, signal_handler);  // On check failures
  signal(SIGABRT, signal_handler);
  signal(SIGFPE, signal_handler);
  signal(SIGSEGV, signal_handler);
}

ngx_uint_t NgxMessageHandler::GetNgxLogLevel(MessageType type) {
  switch (type) {
    case kInfo:
      return NGX_LOG_INFO;
    case kWarning:
      return NGX_LOG_WARN;
    case kError:
      return NGX_LOG_ERR;
    case kFatal:
      return NGX_LOG_ALERT;
  }

  // This should never fall through, but some compilers seem to complain if
  // we don't include this.
  return NGX_LOG_ALERT;
}

void NgxMessageHandler::MessageSImpl(MessageType type,
                                     const GoogleString& message) {
  if (log_ != NULL) {
    ngx_uint_t log_level = GetNgxLogLevel(type);
    ngx_log_error(log_level, log_, 0/*ngx_err_t*/, "[%s %s] %s",
                  kModuleName, kModPagespeedVersion, message.c_str());
  } else {
    GoogleMessageHandler::MessageSImpl(type, message);
  }
  AddMessageToBuffer(type, message);
}

void NgxMessageHandler::FileMessageSImpl(
    MessageType type, const char* file, int line, const GoogleString& message) {
  if (log_ != NULL) {
    ngx_uint_t log_level = GetNgxLogLevel(type);
    ngx_log_error(log_level, log_, 0/*ngx_err_t*/, "[%s %s] %s:%d:%s",
                  kModuleName, kModPagespeedVersion, file, line,
                  message.c_str());
  } else {
    GoogleMessageHandler::FileMessageSImpl(type, file, line, message);
  }
  AddMessageToBuffer(type, file, line, message);
}

}  // namespace net_instaweb