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Some C APIs require the use or structures that contain pointers to buffers (iovec, io_uring, ...). The pointer passing rules would require that these buffers are allocated in C memory and to process this data with Go libraries it would need to be copied. In order to provide a zero-copy way to use these C APIs, this CL implements a Pinner API that allows to pin Go objects, which guarantees that the garbage collector does not move these objects while pinned. This allows to relax the pointer passing rules so that pinned pointers can be stored in C allocated memory or can be contained in Go memory that is passed to C functions. The Pin() method accepts pointers to objects of any type and unsafe.Pointer. Slices and arrays can be pinned by calling Pin() with the pointer to the first element. Pinning of maps is not supported. If the GC collects unreachable Pinner holding pinned objects it panics. If Pin() is called with the other non-pointer types it panics as well. Performance considerations: This change has no impact on execution time on existing code, because checks are only done in code paths, that would panic otherwise. The memory footprint on existing code is one pointer per memory span. Fixes: #46787 Signed-off-by: Sven Anderson <sven@anderson.de> Change-Id: I110031fe789b92277ae45a9455624687bd1c54f2 Reviewed-on: https://go-review.googlesource.com/c/go/+/367296 Auto-Submit: Michael Knyszek <mknyszek@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Michael Knyszek <mknyszek@google.com> Reviewed-by: Than McIntosh <thanm@google.com> Run-TryBot: Michael Knyszek <mknyszek@google.com> |
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| .. | ||
| next | ||
| except.txt | ||
| go1.1.txt | ||
| go1.2.txt | ||
| go1.3.txt | ||
| go1.4.txt | ||
| go1.5.txt | ||
| go1.6.txt | ||
| go1.7.txt | ||
| go1.8.txt | ||
| go1.9.txt | ||
| go1.10.txt | ||
| go1.11.txt | ||
| go1.12.txt | ||
| go1.13.txt | ||
| go1.14.txt | ||
| go1.15.txt | ||
| go1.16.txt | ||
| go1.17.txt | ||
| go1.18.txt | ||
| go1.19.txt | ||
| go1.20.txt | ||
| go1.txt | ||
| README | ||
Files in this directory are data for Go's API checker ("go tool api", in src/cmd/api).
Each file is a list of API features, one per line.
go1.txt (and similarly named files) are frozen once a version has been
shipped. Each file adds new lines but does not remove any.
except.txt lists features that may disappear without breaking true
compatibility.
Starting with go1.19.txt, each API feature line must end in "#nnnnn"
giving the GitHub issue number of the proposal issue that accepted
the new API. This helps with our end-of-cycle audit of new APIs.
The same requirement applies to next/* (described below), which will
become a go1.XX.txt for XX >= 19.
The next/ directory contains the only files intended to be mutated.
Each file in that directory contains a list of features that may be added
to the next release of Go. The files in this directory only affect the
warning output from the go api tool. Each file should be named
nnnnn.txt, after the issue number for the accepted proposal.
(The #nnnnn suffix must also appear at the end of each line in the file;
that will be preserved when next/*.txt is concatenated into go1.XX.txt.)