Use go slices #49
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Use go slices #49
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kamstrup
reviewed
Jan 3, 2023
kamstrup
approved these changes
Jun 2, 2023
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| func TestDecompressTooLarge(t *testing.T) { | ||
| src := []byte{40, 181, 47, 253, 228, 122, 118, 105, 67, 140, 234, 85, 20, 159, 67} | ||
| _, err := Decompress(nil, src) |
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From the test name I gather that the error here is that the decompressed size is too larger for the dst buf (nil)? It would be a bit easier to read if the dst buf was non-nil, like maybe 1 byte or something
| zr.sizes.dstPos = 0 | ||
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| inHdr := (*reflect.SliceHeader)(unsafe.Pointer(&zr.inBuf)) | ||
| outHdr := (*reflect.SliceHeader)(unsafe.Pointer(&dst)) |
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you use the noescape() trick in compressInternal(), but not for dst here... I guess there is no chance stack allocated buffers could be used in this context?
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Fixes #48, #33
I've rewritten how the CGO wrapper is done to achieve two things:
Here's benchmark results against master (run on M1 using go 1.18):
CPU time
Throughput
Now you will notice that many results (particularly ones working with tiny buffers) are reporting being up to 20% slower, turns out this is because the CGO pointers checks are now taking significant amount of time, then again we're talking a few nanoseconds and this is completely negligible with larger buffers, so IMO this isn't that bad.
I've also made the Reader write directly into the provided buffer (if it's large enough), and those benchmarks show the biggest gain - about 5% faster when using large buffers. The ability to use the go slice directly could be also used in the Writer, but let's leave that for another PR.
I've also re-run the benchmarks with
GODEBUG=cgocheck=0, and the results definitely look even better:Had to use a gist, github didn't like this long PR description - https://gist.github.com/mhr3/84f58f62353ef3b9db30288df00fa2b3