4 Commits

Author	SHA1	Message	Date
nielash	810644e873	bisync: add --resync-mode for customizing --resync - fixes #5681 ... Before this change, the path1 version of a file always prevailed during --resync, and many users requested options to automatically select the winner based on characteristics such as newer, older, larger, and smaller. This change adds support for such options. Note that ideally this feature would have been implemented by allowing the existing `--resync` flag to optionally accept string values such as `--resync newer`. However, this would have been a breaking change, as the existing flag is a `bool` and it does not seem to be possible to have a `string` flag that accepts both `--resync newer` and `--resync` (with no argument.) (`NoOptDefVal` does not work for this, as it would force an `=` like `--resync=newer`.) So instead, the best compromise to avoid a breaking change was to add a new `--resync-mode CHOICE` flag that implies `--resync`, while maintaining the existing behavior of `--resync` (which implies `--resync-mode path1`. i.e. both flags are now valid, and either can be used without the other. --resync-mode CHOICE In the event that a file differs on both sides during a `--resync`, `--resync-mode` controls which version will overwrite the other. The supported options are similar to `--conflict-resolve`. For all of the following options, the version that is kept is referred to as the "winner", and the version that is overwritten (deleted) is referred to as the "loser". The options are named after the "winner": - `path1` - (the default) - the version from Path1 is unconditionally considered the winner (regardless of `modtime` and `size`, if any). This can be useful if one side is more trusted or up-to-date than the other, at the time of the `--resync`. - `path2` - same as `path1`, except the path2 version is considered the winner. - `newer` - the newer file (by `modtime`) is considered the winner, regardless of which side it came from. This may result in having a mix of some winners from Path1, and some winners from Path2. (The implementation is analagous to running `rclone copy --update` in both directions.) - `older` - same as `newer`, except the older file is considered the winner, and the newer file is considered the loser. - `larger` - the larger file (by `size`) is considered the winner (regardless of `modtime`, if any). This can be a useful option for remotes without `modtime` support, or with the kinds of files (such as logs) that tend to grow but not shrink, over time. - `smaller` - the smaller file (by `size`) is considered the winner (regardless of `modtime`, if any). For all of the above options, note the following: - If either of the underlying remotes lacks support for the chosen method, it will be ignored and will fall back to the default of `path1`. (For example, if `--resync-mode newer` is set, but one of the paths uses a remote that doesn't support `modtime`.) - If a winner can't be determined because the chosen method's attribute is missing or equal, it will be ignored, and bisync will instead try to determine whether the files differ by looking at the other `--compare` methods in effect. (For example, if `--resync-mode newer` is set, but the Path1 and Path2 modtimes are identical, bisync will compare the sizes.) If bisync concludes that they differ, preference is given to whichever is the "source" at that moment. (In practice, this gives a slight advantage to Path2, as the 2to1 copy comes before the 1to2 copy.) If the files _do not_ differ, nothing is copied (as both sides are already correct). - These options apply only to files that exist on both sides (with the same name and relative path). Files that exist *only* on one side and not the other are *always* copied to the other, during `--resync` (this is one of the main differences between resync and non-resync runs.). - `--conflict-resolve`, `--conflict-loser`, and `--conflict-suffix` do not apply during `--resync`, and unlike these flags, nothing is renamed during `--resync`. When a file differs on both sides during `--resync`, one version always overwrites the other (much like in `rclone copy`.) (Consider using `--backup-dir` to retain a backup of the losing version.) - Unlike for `--conflict-resolve`, `--resync-mode none` is not a valid option (or rather, it will be interpreted as "no resync", unless `--resync` has also been specified, in which case it will be ignored.) - Winners and losers are decided at the individual file-level only (there is not currently an option to pick an entire winning directory atomically, although the `path1` and `path2` options typically produce a similar result.) - To maintain backward-compatibility, the `--resync` flag implies `--resync-mode path1` unless a different `--resync-mode` is explicitly specified. Similarly, all `--resync-mode` options (except `none`) imply `--resync`, so it is not necessary to use both the `--resync` and `--resync-mode` flags simultaneously -- either one is sufficient without the other.	2024-01-20 17:17:01 -05:00
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
nielash	57624629d6	bisync: account for differences in backend features on integration tests - see #5679 ... Before this change, integration tests often could not be run on backends with differing features from the local system that goldenized them. In particular, differences in modtime precision, checksum support, and encoding would cause false positives. After this change, the tests more accurately account for the features of the backend being tested, which allows us to see true positives more clearly, and more meaningfully assess whether a backend is supported.	2024-01-20 14:50:08 -05:00
nielash	422b037087	bisync: fallback to cryptcheck or --download when can't check hash ... Bisync checks file equality before renaming sync conflicts by comparing checksums. Before this change, backends without checksum support (notably Crypt) would fall back to --size-only for these checks, which is not a very safe method (differing files can sometimes have the same size, especially if they're small.) After this change, Crypt remotes fallback to using Cryptcheck so that checksums can be compared. As a last resort when neither Check nor Cryptcheck are available, files are compared using --download so that we can be certain the files are identical regardless of checksum support.	2024-01-20 14:50:08 -05:00