main.cpp

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/*
 * Copyright 2017-present Facebook, Inc.
 *
 * Licensed 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 <folly/init/Init.h>
#include <folly/logging/Init.h>
#include <folly/logging/xlog.h>

#include <folly/logging/example/lib.h>

using namespace example;

// Invoking code that uses XLOG() statements before main() is safe.
// This will use default log settings defined by folly::initializeLoggerDB().
static ExampleObject staticInitialized("static");

// Configure folly to enable INFO+ messages, and everything else to
// enable WARNING+.
//
// Set the default log handler to log asynchronously by default
// (except log messages with level WARNING and above synchronously)
FOLLY_INIT_LOGGING_CONFIG(
    ".=WARNING,folly=INFO; default:async=true,sync_level=WARNING");

int main(int argc, char* argv[]) {
  // Using log macros before calling folly::initLogging() will use the default
  // log settings defined by folly::initializeLoggerDB().  The default behavior
  // is to log WARNING+ messages to stderr.
  XLOG(INFO) << "log messages less than WARNING will be ignored";
  XLOG(ERR) << "error messages before initLogging() will be logged to stderr";

  // folly::Init() will automatically initialize the logging settings based on
  // the FOLLY_INIT_LOGGING_CONFIG declaration above and the --logging command
  // line flag.
  auto init = folly::Init(&argc, &argv);

  // All XLOG() statements in this file will log to the category
  // folly.logging.example.main
  XLOG(INFO, "now the normal log settings have been applied");

  XLOG(DBG1, "log arguments are concatenated: ", 12345, ", ", 92.0);
  XLOGF(DBG1, "XLOGF supports {}-style formatting: {:.3f}", "python", 1.0 / 3);
  XLOG(DBG2) << "streaming syntax is also supported: " << 1234;
  XLOG(DBG2, "if you really want, ", "you can even")
      << " mix function-style and streaming syntax: " << 42;
  XLOGF(DBG3, "and {} can mix {} style", "you", "format") << " and streaming";

  ExampleObject("foo");
  XLOG(INFO) << "main returning";
  return 0;
}