45 lines
1.3 KiB
Racket
45 lines
1.3 KiB
Racket
#lang scribble/doc
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@(require "utils.ss"
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(for-label ffi/unsafe/atomic))
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@title{Atomic Execution}
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@defmodule[ffi/unsafe/atomic]
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@deftogether[(
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@defproc[(start-atomic) void?]
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@defproc[(end-atomic) void?]
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)]{
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Disables and enables context switches at the level of Racket
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threads. Calls to @scheme[start-atomic] and @scheme[end-atomic] can be
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nested.
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Using @scheme[call-as-atomic] is somewhat safer, in that
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@scheme[call-as-atomic] correctly catches exceptions and re-raises
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them after exiting atomic mode. For simple uses, however,
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@scheme[start-atomic] and @scheme[end-atomic] are faster.}
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@defproc[(call-as-atomic [thunk (-> any)]) any]{
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Calls @scheme[thunk] in atomic mode. If @scheme[thunk] raises and
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exception, the exception is caught and re-raised after exiting atomic
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mode.
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When @scheme[call-as-atomic] is used in the dynamic extent of
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@scheme[call-as-atomic], then @scheme[thunk] is simply called directly
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(as a tail call).}
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@defproc[(call-as-nonatomic [thunk (-> any)]) any]{
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Within the dynamic extent of a @scheme[call-as-atomic], calls
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@scheme[thunk] in non-atomic mode. Beware that the current thread
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maybe suspended or terminated by other threads during @scheme[thunk],
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in which case the call never returns.
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When used not in the dynamic extent of @scheme[call-as-atomic],
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@scheme[call-as-nonatomic] raises @scheme[exn:fail:contract].}
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