Hello FPC-Pascal, Monday, April 11, 2011, 6:32:20 PM, you wrote:
JL> Need to read the last 4 lines (txt) of a very large log file 100M bytes, JL> 100k lines or more lots of times - of course I can read through the file in JL> the normal way but this is rather slow. Is there a way to 'read lines from JL> the end'? I note that unix tail or its port to windows does this very fast JL> so guess there must be a fast way to do it in pascal too? The idea is easy, instead reading forward, you read backwards in blocks of, say, 64 Kb and count lines back. If not enougth lines you insert another 64 Kb before and so on. Average line is usually less than 100 bytes, so each 64 Kb are usually more than 600 lines. Read of 64 Kb usually takes the same time as read any lower amount when the block is 4096 bytes aligned. -- Best regards, José _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
