3 Commits

Author	SHA1	Message	Date
Michael Eischer	a5ebd5de4b	restorer: Fix race condition in partialFile.WriteAt ... The restorer can issue multiple calls to WriteAt in parallel. This can result in unexpected orderings of the Truncate and WriteAt calls and sometimes too short restored files.	2022-09-24 21:39:39 +02:00
Michael Eischer	5b6a77058a	Enable sparseness only conditionally ... We can either preallocate storage for a file or sparsify it. This detects a pack file as sparse if it contains an all zero block or consists of only one block. As the file sparsification is just an approximation, hide it behind a `--sparse` parameter.	2022-09-24 21:20:00 +02:00
greatroar	5d4568d393	Write sparse files in restorer ... This writes files by using (*os.File).Truncate, which resolves to the truncate system call on Unix. Compared to the naive loop, for _, b := range p { if b != 0 { return false } } the optimized allZero is about 10× faster: name old time/op new time/op delta AllZero-8 1.09ms ± 1% 0.09ms ± 1% -92.10% (p=0.000 n=10+10) name old speed new speed delta AllZero-8 3.84GB/s ± 1% 48.59GB/s ± 1% +1166.51% (p=0.000 n=10+10)	2022-09-24 21:18:48 +02:00