dippi9845 / fft Goto Github PK

Add class reader for temp file

This class can read a temporary file that is interrupted the download and find the last number of block written.

Possible solution

First

The class splits the file in block of defined dimension.
now for every block create an checksum, and send it to the server, if is correct go to the next block
if is incorrect request the block to the server and replace it to the file.

Second

The class splits the file in block of defined dimension.
now for every block create an checksum, the same the server, then the client request the list of checksum
and try to deduce the missing blocks and the position, then the client request only the missing blocks
and place it in the correct position.

Third

In theory is the most probably case, couse the previos two solutions works even for a block loss, but this don't
but on the other hand is much more faster:

1. split file into blocks and calculate checksum (client and server)
2. if the list of client has the same hashs withthe same order, download the missing blocks keeping ordered

there futher to say, the last block is high probably that has a wrong checksum, couse the interruption of downlaod
doesn't coincide with the end of the block (probability 1/block_size tipically 1/1024 that is less than 0.1%) so the last checksum is different coused by the difference of length of the last block, so replace the block

change protocl of trasfission of file, this one is too slow

Make a way to store temporary file during download , then afert download compleated i will be named as the choosen file