SC-13: batch mode (--write-batch, --read-batch) - #16
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Verified via real rsync's batch.c before writing any code: a real batch
file isn't a separate serialization format, it's the raw multiplexed
wire-protocol byte stream (protocol-version-coupled, forced MD4/MD5,
a data-stream-flags bitmap), captured to disk via the same low-level
I/O the live connection uses. Byte-compatibility would mean
reimplementing real rsync's actual wire protocol - exactly what SC-6,
SC-9, and SC-16 each already declined to take on.
Chose Option A explicitly: grsync's own gob-based batch format, NOT
byte-compatible with real rsync's batch files. Architectural payoff:
since Sender only ever writes one FrameFileList and one FrameDelta per
file down its connection, a batch file is just a byte-for-byte tee of
that stream via the existing WriteFrame/ReadFrame functions.
--read-batch reuses pipeline.Receiver completely unchanged, fed
{Reader: batchFile, Writer: io.Discard} instead of a live connection -
zero pipeline-level code changes.
Verified against real rsync source: --write-batch+--read-batch together
is a hard error there too; real rsync silently disables --write-batch
under --dry-run, replicated with an explicit note rather than silent
mimicry.
Self-review: a --write-batch run failing partway would leave a
truncated, misleading batch file on disk - fixed to remove it on any
non-success path, with a regression test.
Scope, disclosed not silent: local/SSH destinations supported,
rsync:// daemon destinations rejected outright (handshake bytes aren't
cleanly separable from batch-worthy frames without deeper daemon
changes); --only-write-batch and the companion .sh script real rsync
produces are both not implemented.
README: prominent blockquote-style format disclosure at the top of the
new Batch Mode section, echoed in the top-level Status section.
Clean on native Windows and cross-compiled Linux.
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Verified via real rsync's batch.c before writing any code: a real batch file isn't a separate serialization format, it's the raw multiplexed wire-protocol byte stream (protocol-version-coupled, forced MD4/MD5, a data-stream-flags bitmap), captured to disk via the same low-level I/O the live connection uses. Byte-compatibility would mean reimplementing real rsync's actual wire protocol - exactly what SC-6, SC-9, and SC-16 each already declined to take on.
Chose Option A explicitly: grsync's own gob-based batch format, NOT byte-compatible with real rsync's batch files. Architectural payoff: since Sender only ever writes one FrameFileList and one FrameDelta per file down its connection, a batch file is just a byte-for-byte tee of that stream via the existing WriteFrame/ReadFrame functions. --read-batch reuses pipeline.Receiver completely unchanged, fed {Reader: batchFile, Writer: io.Discard} instead of a live connection - zero pipeline-level code changes.
Verified against real rsync source: --write-batch+--read-batch together is a hard error there too; real rsync silently disables --write-batch under --dry-run, replicated with an explicit note rather than silent mimicry.
Self-review: a --write-batch run failing partway would leave a truncated, misleading batch file on disk - fixed to remove it on any non-success path, with a regression test.
Scope, disclosed not silent: local/SSH destinations supported, rsync:// daemon destinations rejected outright (handshake bytes aren't cleanly separable from batch-worthy frames without deeper daemon changes); --only-write-batch and the companion .sh script real rsync produces are both not implemented.
README: prominent blockquote-style format disclosure at the top of the new Batch Mode section, echoed in the top-level Status section.
Clean on native Windows and cross-compiled Linux.