Recently, `test_index_manual_policy_mmap` has been failing on Windows.
The idea addressed by this patch is that we forget to sync the parent
directory with the current implementation of atomic writes.
This was done correctly when we were relying the atomicwrites crate.
*crossing fingers*
Tantivy used to assume that all files could be somehow memory mapped. After this change, Directory return a `FileSlice` that can be reduced and eventually read into an `OwnedBytes` object. Long and blocking io operation are still required by they do not span over the entire file.
* WIP implemented is_compatible
hide Footer::from_bytes from public consumption - only found Footer::extract
used outside the module
Add a new error type for IncompatibleIndex
add a prototypical call to footer.is_compatible() in ManagedDirectory::open_read
to make sure we error before reading it further
* Make error handling more ergonomic
Add an error subtype for OpenReadError and converters to TantivyError
* Remove an unnecessary assert
it's follower by the same check that Errors instead of panicking
* Correct the compatibility check logic
Leave a defensive versioned footer check to make sure we add new logic handling
when we add possible footer versions
Restricted VersionedFooter::from_bytes to be used inside the crate only
remove a half-baked test
* WIP.
* Return an error if index incompatible - closes#662
Enrich the error type with incompatibility
Change return type to Result<bool, TantivyError>, instead of bool
Add an Incompatibility enum that enriches the IncompatibleIndex error variant
with information, which then allows us to generate a developer-friendly hint how
to upgrade library version or switch feature flags for a different compression
algorithm
Updated changelog
Change the signature of is_compatible
Added documentation to the Incompatibility
Added a conditional test on a Footer with lz4 erroring
* code tidy-up
Replace `20` magic constant with COMMON_FOOTER_SIZE
Add a docstring showing how footer is serialised
Add a test for footer length checking
* Add more tests for VersionedFooter
successful and panicking .to_bytes() calls
* Minor changes in footer.rs
* Use `slice::iter` instead of `into_iter` to avoid future breakage
`an_array.into_iter()` currently just works because of the autoref
feature, which then calls `<[T] as IntoIterator>::into_iter`. But
in the future, arrays will implement `IntoIterator`, too. In order
to avoid problems in the future, the call is replaced by `iter()`
which is shorter and more explicit.
* cargo fmt
