Get log files from S3 that were generated within a given timeframe

Amazon S3 log files are named as:

TargetPrefix-YYYY-MM-DD-HH-MM-SS-UniqueNumber

TargetPrefix is what we chose
YYYY-MM-DD-HH-MM-SS is the timestamp
UniqueNumber is something we should not care about

S3 returns a list of Objects (files) in S3 bucket if give give them the desired prefix.

Now, to get a list of log files that were created within a specific timeframe, we can use the following Algo:

beginTime : YYYY-MM-DD-10:25:15
endTime 13:00:00

1) get all files with prefix YYYY-MM-DD-10-25-16 to YYYY-MM-DD-10:25:59
2) get all files with prefix YYYY-MM-DD-10-26 to YYYY-MM-DD-10:59
3) get all files with prefix YYYY-MM-DD-12
3) get all files with prefix YYYY-MM-DD-13

One can further optimise the algorith to get files on 'day of the month' basis. But, that would not be a good idea because the list of files received from S# will be very long.

Following is a Java method for the implementation of the above logic

/**
 * Retuns a List of targetprefix. List is from (beginTime + 1 second) to the
 * hour value of endtime. Minute and second value of endTime is ignored.
 * 
 * @param dbLogTime
 * @param beginTime
 * @return
 */
public List getPrefixList(Timestamp beginTime, Timestamp endTime, String targetPrefix) {
 List prefixList = new ArrayList();

 SimpleDateFormat sdfhr = new SimpleDateFormat("yyyy-MM-dd-HH");
 SimpleDateFormat sdfmin = new SimpleDateFormat("yyyy-MM-dd-HH-mm");
 SimpleDateFormat sdfsec = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss");

 Calendar beginCal = Calendar.getInstance();
 beginCal.setTimeInMillis(beginTime.getTime());
 beginCal.set(Calendar.MILLISECOND, 0);

 Calendar endCal = Calendar.getInstance();
 endCal.setTimeInMillis(endTime.getTime());
 endCal.set(Calendar.MINUTE, 0);
 endCal.set(Calendar.SECOND, 0);
 endCal.set(Calendar.MILLISECOND, 0);

 if (endCal.compareTo(beginCal) < 0) {
  logger.error("Error: Current Time cannot be less than the time in LAST_PROCESS_TIME. currentCal: "
    + sdfsec.format(endCal.getTime()) + ". lastProcessTime: " + sdfsec.format(beginCal.getTime()));
  return prefixList;
 }

 beginCal.add(Calendar.SECOND, 1);
 while (!(beginCal.get(Calendar.SECOND) == 0)) {
  prefixList.add(targetPrefix + "-" + sdfsec.format(beginCal.getTime()));
  beginCal.add(Calendar.SECOND, 1);
 }

 if (endCal.compareTo(beginCal) > 0) {
  while (!(beginCal.get(Calendar.MINUTE) == 0)) {
   prefixList.add(targetPrefix + "-" + sdfmin.format(beginCal.getTime()));
   beginCal.add(Calendar.MINUTE, 1);
  }
 }

 while (endCal.compareTo(beginCal) >= 0) {
  prefixList.add(targetPrefix + "-" + sdfhr.format(beginCal.getTime()));
  beginCal.add(Calendar.HOUR_OF_DAY, 1);
 }

 return prefixList;
}