/// <exception cref="System.IO.IOException"/>
private static TaskLog.LogFileDetail GetLogFileDetail(TaskAttemptID taskid, TaskLog.LogName
filter, bool isCleanup)
{
FilePath indexFile = GetIndexFile(taskid, isCleanup);
BufferedReader fis = new BufferedReader(new InputStreamReader(SecureIOUtils.OpenForRead
(indexFile, ObtainLogDirOwner(taskid), null), Charsets.Utf8));
//the format of the index file is
//LOG_DIR: <the dir where the task logs are really stored>
//stdout:<start-offset in the stdout file> <length>
//stderr:<start-offset in the stderr file> <length>
//syslog:<start-offset in the syslog file> <length>
TaskLog.LogFileDetail l = new TaskLog.LogFileDetail();
string str = null;
try
{
str = fis.ReadLine();
if (str == null)
{
// the file doesn't have anything
throw new IOException("Index file for the log of " + taskid + " doesn't exist.");
}
l.location = Sharpen.Runtime.Substring(str, str.IndexOf(TaskLog.LogFileDetail.Location
) + TaskLog.LogFileDetail.Location.Length);
// special cases are the debugout and profile.out files. They are
// guaranteed
// to be associated with each task attempt since jvm reuse is disabled
// when profiling/debugging is enabled
if (filter.Equals(TaskLog.LogName.Debugout) || filter.Equals(TaskLog.LogName.Profile
))
{
l.length = new FilePath(l.location, filter.ToString()).Length();
l.start = 0;
fis.Close();
return(l);
}
str = fis.ReadLine();
while (str != null)
{
// look for the exact line containing the logname
if (str.Contains(filter.ToString()))
{
str = Sharpen.Runtime.Substring(str, filter.ToString().Length + 1);
string[] startAndLen = str.Split(" ");
l.start = long.Parse(startAndLen[0]);
l.length = long.Parse(startAndLen[1]);
break;
}
str = fis.ReadLine();
}
fis.Close();
fis = null;
}
finally
{
IOUtils.Cleanup(Log, fis);
}
return(l);
}
/// <summary>Read a log file from start to end positions.</summary>
/// <remarks>
/// Read a log file from start to end positions. The offsets may be negative,
/// in which case they are relative to the end of the file. For example,
/// Reader(taskid, kind, 0, -1) is the entire file and
/// Reader(taskid, kind, -4197, -1) is the last 4196 bytes.
/// </remarks>
/// <param name="taskid">the id of the task to read the log file for</param>
/// <param name="kind">the kind of log to read</param>
/// <param name="start">the offset to read from (negative is relative to tail)</param>
/// <param name="end">the offset to read upto (negative is relative to tail)</param>
/// <param name="isCleanup">whether the attempt is cleanup attempt or not</param>
/// <exception cref="System.IO.IOException"/>
public Reader(TaskAttemptID taskid, TaskLog.LogName kind, long start, long end, bool
isCleanup)
{
// find the right log file
TaskLog.LogFileDetail fileDetail = GetLogFileDetail(taskid, kind, isCleanup);
// calculate the start and stop
long size = fileDetail.length;
if (start < 0)
{
start += size + 1;
}
if (end < 0)
{
end += size + 1;
}
start = Math.Max(0, Math.Min(start, size));
end = Math.Max(0, Math.Min(end, size));
start += fileDetail.start;
end += fileDetail.start;
bytesRemaining = end - start;
string owner = ObtainLogDirOwner(taskid);
file = SecureIOUtils.OpenForRead(new FilePath(fileDetail.location, kind.ToString(
)), owner, null);
// skip upto start
long pos = 0;
while (pos < start)
{
long result = file.Skip(start - pos);
if (result < 0)
{
bytesRemaining = 0;
break;
}
pos += result;
}
}
