com.google.common.flogger.backend.log4j2.Log4j2LogDataFormatter Maven / Gradle / Ivy

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A Fluent Logging API for Java
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/*
 * Copyright (C) 2019 The Flogger Authors.
 *
 * 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.
 */

package com.google.common.flogger.backend.log4j2;

import static java.util.logging.Level.WARNING;

import com.google.common.flogger.backend.LogData;
import com.google.common.flogger.backend.Metadata;
import com.google.common.flogger.backend.SimpleMessageFormatter;
import com.google.common.flogger.backend.SimpleMessageFormatter.SimpleLogHandler;
import java.util.logging.Level;

/** Helper to format LogData */
final class Log4j2LogDataFormatter {
  private Log4j2LogDataFormatter() {}

  /**
   * Formats the log message and any metadata for the given {@link LogData}, calling the supplied
   * receiver object with the results.
   */
  static void format(LogData logData, SimpleLogHandler receiver) {
    SimpleMessageFormatter.format(logData, receiver);
  }

  /**
   * Formats the log message in response to an exception during a previous logging attempt. A
   * synthetic error message is generated from the original log data and the given exception is set
   * as the cause. The level of this record is the maximum of WARNING or the original level.
   */
  static void formatBadLogData(
      RuntimeException error, LogData badLogData, SimpleLogHandler receiver) {
    StringBuilder errorMsg =
        new StringBuilder("LOGGING ERROR: ").append(error.getMessage()).append('\n');
    int length = errorMsg.length();
    try {
      appendLogData(badLogData, errorMsg);
    } catch (RuntimeException e) {
      // Reset partially written buffer when an error occurs.
      errorMsg.setLength(length);
      errorMsg.append("Cannot append LogData: ").append(e);
    }

    // Re-target this log message as a warning (or above) since it indicates a real bug.
    Level level =
        badLogData.getLevel().intValue() < WARNING.intValue() ? WARNING : badLogData.getLevel();

    receiver.handleFormattedLogMessage(level, errorMsg.toString(), error);
  }

  /** Appends the given {@link LogData} to the given {@link StringBuilder}. */
  static void appendLogData(LogData data, StringBuilder out) {
    out.append("  original message: ");
    if (data.getTemplateContext() == null) {
      out.append(data.getLiteralArgument());
    } else {
      // We know that there's at least one argument to display here.
      out.append(data.getTemplateContext().getMessage());
      out.append("\n  original arguments:");
      for (Object arg : data.getArguments()) {
        out.append("\n    ").append(SimpleMessageFormatter.safeToString(arg));
      }
    }
    Metadata metadata = data.getMetadata();
    if (metadata.size() > 0) {
      out.append("\n  metadata:");
      for (int n = 0; n < metadata.size(); n++) {
        out.append("\n    ");
        out.append(metadata.getKey(n).getLabel()).append(": ").append(metadata.getValue(n));
      }
    }
    out.append("\n  level: ").append(data.getLevel());
    out.append("\n  timestamp (nanos): ").append(data.getTimestampNanos());
    out.append("\n  class: ").append(data.getLogSite().getClassName());
    out.append("\n  method: ").append(data.getLogSite().getMethodName());
    out.append("\n  line number: ").append(data.getLogSite().getLineNumber());
  }
}