59 lines
2.9 KiB
C
59 lines
2.9 KiB
C
/***********************************************************************/
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/* */
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/* OCaml */
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/* */
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/* Xavier Leroy and Damien Doligez, INRIA Rocquencourt */
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/* */
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/* Copyright 1995 Institut National de Recherche en Informatique et */
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/* en Automatique. All rights reserved. This file is distributed */
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/* under the terms of the GNU Library General Public License, with */
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/* the special exception on linking described in file ../../LICENSE. */
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/* */
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/***********************************************************************/
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#ifndef CAML_THREADS_H
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#define CAML_THREADS_H
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CAMLextern void caml_enter_blocking_section (void);
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CAMLextern void caml_leave_blocking_section (void);
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#define caml_acquire_runtime_system caml_leave_blocking_section
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#define caml_release_runtime_system caml_enter_blocking_section
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/* Manage the master lock around the OCaml run-time system.
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Only one thread at a time can execute OCaml compiled code or
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OCaml run-time system functions.
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When OCaml calls a C function, the current thread holds the master
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lock. The C function can release it by calling
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[caml_release_runtime_system]. Then, another thread can execute OCaml
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code. However, the calling thread must not access any OCaml data,
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nor call any runtime system function, nor call back into OCaml.
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Before returning to its OCaml caller, or accessing OCaml data,
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or call runtime system functions, the current thread must
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re-acquire the master lock by calling [caml_acquire_runtime_system].
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Symmetrically, if a C function (not called from OCaml) wishes to
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call back into OCaml code, it should invoke [caml_acquire_runtime_system]
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first, then do the callback, then invoke [caml_release_runtime_system].
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For historical reasons, alternate names can be used:
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[caml_enter_blocking_section] instead of [caml_release_runtime_system]
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[caml_leave_blocking_section] instead of [caml_acquire_runtime_system]
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Intuition: a ``blocking section'' is a piece of C code that does not
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use the runtime system (typically, a blocking I/O operation).
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*/
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CAMLextern int caml_c_thread_register(void);
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CAMLextern int caml_c_thread_unregister(void);
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/* If a thread is created by C code (instead of by OCaml itself),
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it must be registered with the OCaml runtime system before
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being able to call back into OCaml code or use other runtime system
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functions. Just call [caml_c_thread_register] once.
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Before the thread finishes, it must call [caml_c_thread_unregister].
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Both functions return 1 on success, 0 on error.
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*/
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#endif /* CAML_THREADS_H */
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