MultiProcessFileAppender.cpp

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* Copyright (C) 2006, Novell, Inc. All rights reserved.
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#include "blocxx/BLOCXX_config.h"
#include "blocxx/MultiProcessFileAppender.hpp"
#include "blocxx/Format.hpp"
#include "blocxx/Logger.hpp"
#include "blocxx/LogMessage.hpp"
#include "blocxx/FileSystem.hpp"

#include <fcntl.h>
#ifdef BLOCXX_HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif

namespace BLOCXX_NAMESPACE
{

namespace
{
   using namespace blocxx;

   class FileLock
   {
   public:
      FileLock(File & file)
      : m_file(file)
      {
         m_ok = file.getLock() == 0;
      }

      bool ok() const
      {
         return m_ok;
      }

      ~FileLock()
      {
         if (m_ok)
         {
            m_file.unlock(); // nowhere to report error if unlock fails...
         }
      }

   private:
      File & m_file;
      bool m_ok;
   };

   typedef blocxx::MultiProcessFileAppender app_t;

   UInt64 kbytesToBytes(UInt64 max_size)
   {
      UInt64 const oneK = 1024;
      UInt64 const biggest = UInt64(-1); // largest possible UInt64
      return(
         max_size == app_t::NO_MAX_LOG_SIZE ? biggest
         : max_size > biggest / oneK ? biggest
         : max_size * oneK
      );
   }

}

MultiProcessFileAppender::MultiProcessFileAppender(
   const StringArray& components,
   const StringArray& categories,
   const String & filename,
   const String& pattern,
   UInt64 maxFileSize,
   UInt32 maxBackupIndex
)
   : LogAppender(components, categories, pattern)
   , m_filename(filename)
   , m_maxFileSize(kbytesToBytes(maxFileSize))
   , m_maxBackupIndex(maxBackupIndex)
{
   m_log = FileSystem::openForAppendOrCreateFile(filename);
   m_lock = FileSystem::openOrCreateFile(filename + ".lock");

   if (!m_log)
   {
      String msg = "Cannot create log file " + filename;
      BLOCXX_THROW(LoggerException, msg.c_str());
   }
   if (!m_lock)
   {
      String msg = "Cannot create lock file for log file " + filename + ".lock";
      BLOCXX_THROW(LoggerException, msg.c_str());
   }
}

MultiProcessFileAppender::~MultiProcessFileAppender()
{
}

void MultiProcessFileAppender::doProcessLogMessage(
   const String& formattedMessage, const LogMessage& message) const
{
   // On error, we just return, since doProcessLogMessage should not throw

   if (!m_log || !m_lock)
   {
      return;
   }

   FileLock lock(m_lock);
   if (!lock.ok())
   {
      return;
   }

   UInt64 size = m_log.size();

   if (size >= m_maxFileSize)
   {
      // Log file has been rotated
      File f = FileSystem::openForAppendOrCreateFile(m_filename);
      f.swap(m_log);
      if (!m_log)
      {
         return;
      }
      size = m_log.size();
   }

   String s = formattedMessage + "\n";
   m_log.write(s.c_str(), s.length());
   m_log.flush();
   size += s.length();

   // handle log rotation
   if (size >= m_maxFileSize)
   {
      // do the roll over
      m_log.close();

      if (m_maxBackupIndex > 0)
      {
         // delete the oldest file first, if it exists
         FileSystem::removeFile(m_filename + '.' + String(m_maxBackupIndex));

         // increment the numbers on all the files, if they exist
         for (UInt32 i = m_maxBackupIndex - 1; i >= 1; --i)
         {
            FileSystem::renameFile(m_filename + '.' + String(i), m_filename + '.' + String(i + 1));
         }

         if (!FileSystem::renameFile(m_filename, m_filename + ".1"))
         {
            // if we can't rename it, at least don't write to it anymore
            return;
         }
      }

      // open new log file
      File f = FileSystem::openForAppendOrCreateFile(m_filename);
      f.swap(m_log);
   }
}

} // end namespace BLOCXX_NAMESPACE