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>
This CL moves many cgo test conditions out of dist and into the tests
themselves, now that they can use the testenv.Must* helpers.
This refines a lot of the conditions, which happens to have the effect
of enabling many tests on Android and iOS that are disabled by
too-coarse GOOS checks in dist today.
Fixes#15919.
Change-Id: I2947526b08928d2f7f89f107b5b2403b32092ed8
Reviewed-on: https://go-review.googlesource.com/c/go/+/495918
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
This moves most misc/cgo tests to cmd/cgo/internal. This is mostly a
trivial rename and updating dist/test.go for the new paths, plus
excluding these packages from regular dist test registration. A few
tests were sensitive to what path they ran in, so we update those.
This will let these tests access facilities in internal/testenv.
For #37486.
Change-Id: I3ed417c7c22d9b667f2767c0cb1f59118fcd4af6
Reviewed-on: https://go-review.googlesource.com/c/go/+/492720
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
2023-05-12 11:59:56 +00:00
Renamed from misc/cgo/errors/ptr_test.go (Browse further)
