/src/logging-log4cxx/src/main/cpp/cacheddateformat.cpp

Source
/*
 * 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.
 */
#define __STDC_CONSTANT_MACROS
#define NOMINMAX /* tell wnidows not to define min/max macros */
#include <log4cxx/logstring.h>
#include <log4cxx/helpers/cacheddateformat.h>
#include <log4cxx/helpers/pool.h>
#include <limits>
#include <log4cxx/helpers/exception.h>

using namespace LOG4CXX_NS;
using namespace LOG4CXX_NS::helpers;
using namespace LOG4CXX_NS::pattern;

struct CachedDateFormat::CachedDateFormatPriv
{
  CachedDateFormatPriv(DateFormatPtr dateFormat, int expiration1) :
    formatter(dateFormat),
    millisecondStart(0),
    slotBegin(std::numeric_limits<log4cxx_time_t>::min()),
    cache(50, 0x20),
    expiration(expiration1),
    previousTime(std::numeric_limits<log4cxx_time_t>::min())
  {}

  /**
   *   Wrapped formatter.
   */
  LOG4CXX_NS::helpers::DateFormatPtr formatter;

  /**
   *  Index of initial digit of millisecond pattern or
   *   UNRECOGNIZED_MILLISECONDS or NO_MILLISECONDS.
   */
  mutable int millisecondStart;

  /**
   *  Integral second preceding the previous convered Date.
   */
  mutable log4cxx_time_t slotBegin;


  /**
   *  Cache of previous conversion.
   */
  mutable LogString cache;


  /**
   *  Maximum validity period for the cache.
   *  Typically 1, use cache for duplicate requests only, or
   *  1000000, use cache for requests within the same integral second.
   */
  const int expiration;

  /**
   *  Date requested in previous conversion.
   */
  mutable log4cxx_time_t previousTime;
};


/**
*  Supported digit set.  If the wrapped DateFormat uses
*  a different unit set, the millisecond pattern
*  will not be recognized and duplicate requests
*  will use the cache.
*/
const logchar CachedDateFormat::digits[] = { 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0 };


/**
 * First magic number (in microseconds) used to detect
 * the millisecond position.
 */
const int CachedDateFormat::magic1 = 654000;


/**
 *  Expected representation of first magic number in milliseconds.
 */
const logchar CachedDateFormat::magicString1[] = { 0x36, 0x35, 0x34, 0 };


/**
 * Second magic number (in microseconds) used to detect
 * the millisecond position.
 */
const int CachedDateFormat::magic2 = 987000;


/**
 *  Expected representation of second magic number in milliseconds.
 */
const logchar CachedDateFormat::magicString2[] = { 0x39, 0x38, 0x37, 0};


/**
 *  Expected representation of 0 milliseconds.
 */
const logchar CachedDateFormat::zeroString[] = { 0x30, 0x30, 0x30, 0 };

/**
 *  Creates a new CachedDateFormat object.
 *  @param dateFormat Date format, may not be null.
 *  @param expiration maximum cached range in milliseconds.
 *    If the dateFormat is known to be incompatible with the
 *      caching algorithm, use a value of 0 to totally disable
 *      caching or 1 to only use cache for duplicate requests.
 */
CachedDateFormat::CachedDateFormat(const DateFormatPtr& dateFormat,
  int expiration1) :
  m_priv(std::make_unique<CachedDateFormatPriv>(dateFormat, expiration1))
{
  if (dateFormat == NULL)
  {
    throw NullPointerException(LOG4CXX_STR("dateFormat"));
  }

  if (expiration1 < 0)
  {
    throw IllegalArgumentException(LOG4CXX_STR("expiration must be non-negative"));
  }
}

CachedDateFormat::~CachedDateFormat() {}


/**
 * Finds start of millisecond field in formatted time.
 * @param time long time, must be integral number of seconds
 * @param formatted String corresponding formatted string
 * @param formatter DateFormat date format
 * @return int position in string of first digit of milliseconds,
 *    -1 indicates no millisecond field, -2 indicates unrecognized
 *    field (likely RelativeTimeDateFormat)
 */
int CachedDateFormat::findMillisecondStart(
  log4cxx_time_t time, const LogString& formatted,
  const DateFormatPtr& formatter)
{

  log4cxx_time_t slotBegin = (time / 1000000) * 1000000;

  if (slotBegin > time)
  {
    slotBegin -= 1000000;
  }

  int millis = (int) (time - slotBegin) / 1000;

  // the magic numbers are in microseconds
  int magic = magic1;
  LogString magicString(magicString1);

  if (millis == magic1 / 1000)
  {
    magic = magic2;
    magicString = magicString2;
  }

  LogString plusMagic;
  formatter->format(plusMagic, slotBegin + magic);

  /**
   *   If the string lengths differ then
   *      we can't use the cache except for duplicate requests.
   */
  if (plusMagic.length() != formatted.length())
  {
    return UNRECOGNIZED_MILLISECONDS;
  }
  else
  {
    // find first difference between values
    for (LogString::size_type i = 0; i < formatted.length(); i++)
    {
      if (formatted[i] != plusMagic[i])
      {
        //
        //   determine the expected digits for the base time
        const logchar abc[] = { 0x41, 0x42, 0x43, 0 };
        LogString formattedMillis(abc);
        millisecondFormat(millis, formattedMillis, 0);

        LogString plusZero;
        formatter->format(plusZero, slotBegin);

        // Test if the next 1..3 characters match the magic string, main problem is that magic
        // available millis in formatted can overlap. Therefore the current i is not always the
        // index of the first millis char, but may be already within the millis. Besides that
        // the millis can occur everywhere in formatted. See LOGCXX-420 and following.
        size_t  magicLength     = magicString.length();
        size_t  overlapping     = magicString.find(plusMagic[i]);
        int     possibleRetVal  = int(i - overlapping);

        if (plusZero.length() == formatted.length()
          && regionMatches(magicString,       0, plusMagic,   possibleRetVal, magicLength)
          && regionMatches(formattedMillis,   0, formatted,   possibleRetVal, magicLength)
          && regionMatches(zeroString,        0, plusZero,    possibleRetVal, magicLength)
          // The following will and should fail for patterns with more than one SSS because
          // we only seem to be able to change one SSS in e.g. format and need to reformat the
          // whole string in other cases.
          && (formatted.length() == possibleRetVal + magicLength
            || plusZero.compare(possibleRetVal + magicLength,
              LogString::npos, plusMagic, possibleRetVal + magicLength, LogString::npos) == 0))
        {
          return possibleRetVal;
        }
        else
        {
          return UNRECOGNIZED_MILLISECONDS;
        }
      }
    }
  }

  return NO_MILLISECONDS;
}
#if LOG4CXX_ABI_VERSION <= 15
int CachedDateFormat::findMillisecondStart(
  log4cxx_time_t time, const LogString& formatted,
  const DateFormatPtr& formatter,
  Pool& pool)
{
  return findMillisecondStart(time, formatted, formatter);
}
#endif

/**
 * Formats a millisecond count into a date/time string.
 *
 *  @param now Number of milliseconds after midnight 1 Jan 1970 GMT.
 *  @param sbuf the string buffer to write to
 */
void CachedDateFormat::format( LOG4CXX_FORMAT_TIME_FORMAL_PARAMETERS ) const
{

  //
  // If the current requested time is identical to the previously
  //     requested time, then append the cache contents.
  //
  if (tm == m_priv->previousTime)
  {
    toAppendTo.append(m_priv->cache);
    return;
  }

  //
  //   If millisecond pattern was not unrecognized
  //     (that is if it was found or milliseconds did not appear)
  //
  if (m_priv->millisecondStart != UNRECOGNIZED_MILLISECONDS)
  {
    //    Check if the cache is still valid.
    //    If the requested time is within the same integral second
    //       as the last request and a shorter expiration was not requested.
    if (tm < m_priv->slotBegin + m_priv->expiration
      && tm >= m_priv->slotBegin
      && tm < m_priv->slotBegin + 1000000L)
    {
      //
      //    if there was a millisecond field then update it
      //
      if (m_priv->millisecondStart >= 0)
      {
        millisecondFormat((int) ((tm - m_priv->slotBegin) / 1000), m_priv->cache, m_priv->millisecondStart);
      }

      //
      //   update the previously requested time
      //      (the slot begin should be unchanged)
      m_priv->previousTime = tm;
      toAppendTo.append(m_priv->cache);

      return;
    }
  }

  //
  //  could not use previous value.
  //    Call underlying formatter to format date.
  m_priv->cache.erase(m_priv->cache.begin(), m_priv->cache.end());
  m_priv->formatter->format(m_priv->cache, tm);
  toAppendTo.append(m_priv->cache);
  m_priv->previousTime = tm;
  m_priv->slotBegin = (m_priv->previousTime / 1000000) * 1000000;

  if (m_priv->slotBegin > m_priv->previousTime)
  {
    m_priv->slotBegin -= 1000000;
  }

  //
  //    if the milliseconds field was previous found
  //       then reevaluate in case it moved.
  //
  if (m_priv->millisecondStart >= 0)
  {
    m_priv->millisecondStart = findMillisecondStart(tm, m_priv->cache, m_priv->formatter);
  }
}

/**
 *   Formats a count of milliseconds (0-999) into a numeric representation.
 *   @param millis Millisecond count between 0 and 999.
 *   @buf String buffer, may not be null.
 *   @offset Starting position in buffer, the length of the
 *       buffer must be at least offset + 3.
 */
void CachedDateFormat::millisecondFormat(int millis,
  LogString& buf,
  int offset)
{
  buf[offset] = digits[millis / 100];
  buf[offset + 1] = digits[(millis / 10) % 10];
  buf[offset + 2] = digits[millis  % 10];
}

/**
 * Set timezone.
 *
 * @remarks Setting the timezone using getCalendar().setTimeZone()
 * will likely cause caching to misbehave.
 * @param timeZone TimeZone new timezone
 */
void CachedDateFormat::setTimeZone(const TimeZonePtr& timeZone)
{
  m_priv->formatter->setTimeZone(timeZone);
  m_priv->previousTime = std::numeric_limits<log4cxx_time_t>::min();
  m_priv->slotBegin = std::numeric_limits<log4cxx_time_t>::min();
}



void CachedDateFormat::numberFormat( LOG4CXX_FORMAT_NUMBER_FORMAL_PARAMETERS ) const
{
  m_priv->formatter->numberFormat(toAppendTo, n);
}


/**
 * Gets maximum cache validity for the specified SimpleDateTime
 *    conversion pattern.
 *  @param pattern conversion pattern, may not be null.
 *  @returns Duration in microseconds from an integral second
 *      that the cache will return consistent results.
 */
int CachedDateFormat::getMaximumCacheValidity(const LogString& pattern)
{
  //
  //   If there are more "S" in the pattern than just one "SSS" then
  //      (for example, "HH:mm:ss,SSS SSS"), then set the expiration to
  //      one millisecond which should only perform duplicate request caching.
  //
  const logchar S = 0x53;
  const logchar SSS[] = { 0x53, 0x53, 0x53, 0 };
  size_t firstS = pattern.find(S);
  size_t len = pattern.length();

  //
  //   if there are no S's or
  //      three that start with the first S and no fourth S in the string
  //
  if (firstS == LogString::npos ||
    (len >= firstS + 3 && pattern.compare(firstS, 3, SSS) == 0
      && (len == firstS + 3 ||
        pattern.find(S, firstS + 3) == LogString::npos)))
  {
    return 1000000;
  }

  return 1000;
}


/**
* Tests if two string regions are equal.
* @param target target string.
* @param toffset character position in target to start comparison.
* @param other other string.
* @param ooffset character position in other to start comparison.
* @param len length of region.
* @return true if regions are equal.
*/
bool CachedDateFormat::regionMatches(
  const LogString& target,
  size_t toffset,
  const LogString& other,
  size_t ooffset,
  size_t len)
{
  return target.compare(toffset, len, other, ooffset, len) == 0;
}


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Created: 2026-09-04 06:38