Sync messages encode changes as length prefixed byte arrays. We were
calculating the length using the uncompressed bytes of a change but
encoding the bytes of the change using the (possibly) compressed bytes.
This meant that if a change was large enough to compress then it would
fail to decode. Switch to using uncompressed bytes in sync messages.
The logic for loading compressed document chunks has a check that the
`max_op` of a change is valid. This check was overly strict in that it
checked that the max op was strictly larger than the max op of a
previous strange - this rejects valid documents which contain changes
with no ops in them, in which case the max op can be equal to the max op
of the previous change. Loosen the logic to allow empty changes.
The logic for reconstructing changes from the compressed document format
records operations which set a key in an object so that it can later
reconstruct delete operations from the successor list of the document
format operations. The logic to do this was only recording set
operations and not `make*` operations. This meant that delete operations
targeting `make*` operations could not be loaded correctly.
Correctly record `make*` operations for later use in constructing delete
operations.
The compressed document format includes at the end of the document chunk
the indicies of the heads of the document. Older versions of the
javascript implementation do not include these indicies so we allow them
to be omitted when decoding.
Whilst we're here add some tracing::trace logs to make it easier to
understand where parsing is failing.
This is achieved by liberal use of feature flags. Main additions are:
* Build the OpSet more efficiently when loading from compressed
document storage using a DocObserver as implemented in
`automerge::op_tree::load`
* Reimplement the parsing login in the various types in
`automerge::sync`
There are numerous other small changes required to get the types to line
up.
Signed-off-by: Alex Good <alex@memoryandthought.me>
Implement parsing the binary format using the new parser library and the
new encoding types. This is superior to the previous parsing
implementation in that invalid data should never cause panics and it
exposes and interface to construct an OpSet from a saved document much
more efficiently.
Signed-off-by: Alex Good <alex@memoryandthought.me>
We have parsing needs which are slightly more complex than just reading
stuff from a buffer, but not complex enough to justify a dependency on a
parsing library. Implement a simple parser combinator library for use in
parsing the binary storage format.
Signed-off-by: Alex Good <alex@memoryandthought.me>
