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Merged
cperciva merged 1 commit into from
Dec 20, 2025
Merged

Skip auto-lowmem logic for large files #667

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14 changes: 11 additions & 3 deletions tar/ccache/ccache_entry.c
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Original file line number Diff line number Diff line change
Expand Up @@ -552,11 +552,19 @@ ccache_entry_writefile(CCACHE_ENTRY * cce, TAPE_W * cookie,
cce->ccr->size = cce->size_new;
cce->ccr->mtime = cce->mtime_new;

/*
* Decide if we want to keep a trailer: We follow the policy provided
* by the caller (record a trailer unless notrailer != 0) unless we're
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@gperciva gperciva Jul 31, 2025

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I was a bit confused by the "unless notrailer != 0" bit in the comment, since that's not part of this "paragraph". If we already have notrailer = 1, then that only applies below on line 567.

For clarity, I'd be tempted to put lines 561-563 inside an

if (notrailer == 0) {
}

OTOH, you might take the view that anybody reading this section should be able to figure it out, so shrug.

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@cperciva cperciva Aug 1, 2025

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Yeah, I agree it's not the clearest code but I don't want to complicate things by adding another conditional either. I think this is fine.

* spending too much memory keeping track of trailers *and* this file
* is under 10 MB.
*/
if ((cce->cci->trailerusage > cce->cci->chunksusage * 2) &&
(cce->ccr->size < 10 * 1024 * 1024))
notrailer = 1;

/* Ask the multitape layer to inform us about later chunks. */
writetape_setcallback(cookie, callback_addchunk,
((cce->cci->trailerusage > cce->cci->chunksusage * 2) ||
(notrailer != 0)) ? callback_faketrailer : callback_addtrailer,
cce);
notrailer ? callback_faketrailer : callback_addtrailer, cce);

/* Success! */
return (skiplen);
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