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edited async-apply description

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John Clements 2010-11-16 16:54:56 -08:00
parent 584287483b
commit b2edac3179
1 changed files with 10 additions and 7 deletions
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17
collects/scribblings/foreign/types.scrbl
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@ -401,19 +401,22 @@ procedure with the generated procedure type can be applied in a
foreign thread (i.e., an OS-level thread other than the one used to
run Racket). The call in the foreign thread is transferred to the
OS-level thread that runs Racket, but the Racket-level thread (in the
sense of @racket[thread]) is unspecified; the job of
@scheme[async-apply] is to arrange for the callback procedure to be
run in a suitable Racket thread. The @scheme[async-apply] function is
sense of @racket[thread]) is unspecified; the job of the provided
@scheme[async-apply] procedure is to arrange for the callback procedure to be
run in a suitable Racket thread. The given @scheme[async-apply] procedure is
applied to a thunk that encapsulates the specific callback invocation,
and the foreign OS-level thread blocks until the thunk is called and
completes; the thunk must be called exactly once, and the callback
invocation must return normally. The @scheme[async-apply] procedure
invocation must return normally. The given @scheme[async-apply] procedure
itself is called in atomic mode (see @scheme[atomic?] above). If the
callback is known to complete quickly, requires no synchronization,
and works independent of the Racket thread in which it runs, then
@scheme[async-apply] can apply the thunk directly. Otherwise,
@racket[async-apply] must arrange for the thunk to be applied in a
suitable Racket thread sometime after @racket[async-apply] itself
it is safe for the given
@scheme[async-apply] procedure to apply the thunk directly. Otherwise,
the given @racket[async-apply] procedure
must arrange for the thunk to be applied in a
suitable Racket thread sometime after the given
@racket[async-apply] procedure itself
returns; if the thunk raises an exception or synchronizes within an
unsuitable Racket-level thread, it can deadlock or otherwise damage
the Racket process. Foreign-thread detection to trigger