rclone/cmd/bisync/testdata/test_compare_all/scenario.txt
nielash b4216648e4 bisync: full support for comparing checksum, size, modtime - fixes #5679 fixes #5683 fixes #5684 fixes #5675
Before this change, bisync could only detect changes based on modtime, and
would refuse to run if either path lacked modtime support. This made bisync
unavailable for many of rclone's backends. Additionally, bisync did not account
for the Fs's precision when comparing modtimes, meaning that they could only be
reliably compared within the same side -- not against the opposite side. Size
and checksum (even when available) were ignored completely for deltas.

After this change, bisync now fully supports comparing based on any combination
of size, modtime, and checksum, lifting the prior restriction on backends
without modtime support. The comparison logic considers the backend's
precision, hash types, and other features as appropriate.

The comparison features optionally use a new --compare flag (which takes any
combination of size,modtime,checksum) and even supports some combinations not
otherwise supported in `sync` (like comparing all three at the same time.) By
default (without the --compare flag), bisync inherits the same comparison
options as `sync` (that is: size and modtime by default, unless modified with
flags such as --checksum or --size-only.) If the --compare flag is set, it will
override these defaults.

If --compare includes checksum and both remotes support checksums but have no
hash types in common with each other, checksums will be considered only for
comparisons within the same side (to determine what has changed since the prior
sync), but not for comparisons against the opposite side. If one side supports
checksums and the other does not, checksums will only be considered on the side
that supports them. When comparing with checksum and/or size without modtime,
bisync cannot determine whether a file is newer or older -- only whether it is
changed or unchanged. (If it is changed on both sides, bisync still does the
standard equality-check to avoid declaring a sync conflict unless it absolutely
has to.)

Also included are some new flags to customize the checksum comparison behavior
on backends where hashes are slow or unavailable. --no-slow-hash and
--slow-hash-sync-only allow selectively ignoring checksums on backends such as
local where they are slow. --download-hash allows computing them by downloading
when (and only when) they're otherwise not available. Of course, this option
probably won't be practical with large files, but may be a good option for
syncing small-but-important files with maximum accuracy (for example, a source
code repo on a crypt remote.) An additional advantage over methods like
cryptcheck is that the original file is not required for comparison (for
example, --download-hash can be used to bisync two different crypt remotes with
different passwords.)

Additionally, all of the above are now considered during the final --check-sync
for much-improved accuracy (before this change, it only compared filenames!)

Many other details are explained in the included docs.
2024-01-20 16:08:06 -05:00

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test changes compare-all
# Exercise all of the various file change scenarios
# - New on Path2 file10
# - Newer on Path2 file1
# - New on Path1 file11
# - Newer on Path1 file2
# - Deleted on Path2 file3
# - Deleted on Path1 file4
# - Changed on Path2 and on Path1 file5 (file5r, file5l)
# - Newer on Path2 and deleted on Path1 file6
# - Newer on Path1 and deleted on Path2 file7
# - Deleted on both paths file8
test initial bisync
bisync resync compare-all
test make modifications on both paths
test new on path2 - file10
touch-copy 2001-01-02 {datadir/}file10.txt {path2/}
test newer on path2 - file1
touch-copy 2001-01-02 {datadir/}file1.txt {path2/}
test new on path1 - file11
touch-copy 2001-01-02 {datadir/}file11.txt {path1/}
test newer on path1 - file2
touch-copy 2001-01-02 {datadir/}file2.txt {path1/}
test deleted on path2 - file3
delete-file {path2/}file3.txt
test deleted on path1 - file4
delete-file {path1/}file4.txt
test deleted on both paths - file8
delete-file {path1/}file8.txt
delete-file {path2/}file8.txt
test changed on both paths - file5 (file5R, file5L)
touch-glob 2001-01-02 {datadir/} file5R.txt
copy-as {datadir/}file5R.txt {path2/} file5.txt
touch-glob 2001-03-04 {datadir/} file5L.txt
copy-as {datadir/}file5L.txt {path1/} file5.txt
test newer on path2 and deleted on path1 - file6
touch-copy 2001-01-02 {datadir/}file6.txt {path2/}
delete-file {path1/}file6.txt
test newer on path1 and deleted on path2 - file7
touch-copy 2001-01-02 {datadir/}file7.txt {path1/}
delete-file {path2/}file7.txt
test bisync run
bisync compare-all