Issue/107 Reuse cached SANE_Parameters in SaneDev_snap instead of a second sane_get_parameters call - #109
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carygravel wants to merge 2 commits into
Open
Issue/107 Reuse cached SANE_Parameters in SaneDev_snap instead of a second sane_get_parameters call#109carygravel wants to merge 2 commits into
carygravel wants to merge 2 commits into
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…_get_parameters call Some SANE backends (e.g. Epson's epsonscan2) return SANE_STATUS_INVAL on a second sane_get_parameters() call after sane_start. The Python wrapper's get_parameters() already retrieves the parameters successfully, but snap() then calls sane_get_parameters() again internally and fails on those backends, raising `_sane.error: Invalid argument`. Cache the parameters from the most recent get_parameters() call in the SaneDevObject and reuse them in SaneDev_snap, falling back to sane_get_parameters() only when the cache is empty (snap called without a prior get_parameters). Invalidate the cache on sane_start() and update it when a subsequent frame is started.
Add a mock libsane backend (tests/mock/libsane_mock.c) that replicates the INVAL-on-second-sane_get_parameters behavior and a regression test that fails without the fix (tests/test_snap_params_cache.py). The test exercises snap() through the cached-params path at depth-8, depth-1, and snap without a prior get_parameters. Wire the test into CI.
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Some SANE backends (e.g. Epson's epsonscan2) return SANE_STATUS_INVAL on a second sane_get_parameters() call after sane_start. The Python wrapper's get_parameters() already retrieves the parameters successfully, but snap() then calls sane_get_parameters() again internally and fails on those backends, raising
_sane.error: Invalid argument.Cache the parameters from the most recent get_parameters() call in the SaneDevObject and reuse them in SaneDev_snap, falling back to sane_get_parameters() only when the cache is empty (snap called without a prior get_parameters). Invalidate the cache on sane_start() and update it when a subsequent frame is started.