Thread(3o) OCaml library Thread(3o)
NAME
Thread - Lightweight threads for Posix 1003.1c and Win32.
Module
Module Thread
Documentation
Module Thread
: sig end
Lightweight threads for Posix 1003.1c and Win32.
type t
The type of thread handles.
Thread creation and termination
val create : ('a -> 'b) -> 'a -> t
Thread.create funct arg creates a new thread of control, in which the
function application funct arg is executed concurrently with the other
threads of the program. The application of Thread.create returns the
handle of the newly created thread. The new thread terminates when the
application funct arg returns, either normally or by raising an un-
caught exception. In the latter case, the exception is printed on
standard error, but not propagated back to the parent thread. Simi-
larly, the result of the application funct arg is discarded and not di-
rectly accessible to the parent thread.
val self : unit -> t
Return the handle for the thread currently executing.
val id : t -> int
Return the identifier of the given thread. A thread identifier is an
integer that identifies uniquely the thread. It can be used to build
data structures indexed by threads.
val exit : unit -> unit
Terminate prematurely the currently executing thread.
val kill : t -> unit
This function was supposed to terminate prematurely the thread whose
handle is given. It is not currently implemented due to problems with
cleanup handlers on many POSIX 1003.1c implementations. It always
raises the Invalid_argument exception.
Suspending threads
val delay : float -> unit
delay d suspends the execution of the calling thread for d seconds. The
other program threads continue to run during this time.
val join : t -> unit
join th suspends the execution of the calling thread until the thread
th has terminated.
val yield : unit -> unit
Re-schedule the calling thread without suspending it. This function
can be used to give scheduling hints, telling the scheduler that now is
a good time to switch to other threads.
Waiting for file descriptors or processes
The functions below are leftovers from an earlier, VM-based threading
system. The Unix module provides equivalent functionality, in a more
general and more standard-conformant manner. It is recommended to use
Unix functions directly.
val wait_read : Unix.file_descr -> unit
This function does nothing in the current implementation of the thread-
ing library and can be removed from all user programs.
val wait_write : Unix.file_descr -> unit
This function does nothing in the current implementation of the thread-
ing library and can be removed from all user programs.
val wait_timed_read : Unix.file_descr -> float -> bool
See Thread.wait_timed_write .
val wait_timed_write : Unix.file_descr -> float -> bool
Suspend the execution of the calling thread until at least one charac-
ter or EOF is available for reading ( wait_timed_read ) or one charac-
ter can be written without blocking ( wait_timed_write ) on the given
Unix file descriptor. Wait for at most the amount of time given as sec-
ond argument (in seconds). Return true if the file descriptor is ready
for input/output and false if the timeout expired. The same function-
ality can be achieved with Unix.select .
val select : Unix.file_descr list -> Unix.file_descr list ->
Unix.file_descr list -> float -> Unix.file_descr list * Unix.file_descr
list * Unix.file_descr list
Same function as Unix.select . Suspend the execution of the calling
thread until input/output becomes possible on the given Unix file de-
scriptors. The arguments and results have the same meaning as for
Unix.select .
val wait_pid : int -> int * Unix.process_status
Same function as Unix.waitpid . wait_pid p suspends the execution of
the calling thread until the process specified by the process identi-
fier p terminates. Returns the pid of the child caught and its termina-
tion status, as per Unix.wait .
Management of signals
Signal handling follows the POSIX thread model: signals generated by a
thread are delivered to that thread; signals generated externally are
delivered to one of the threads that does not block it. Each thread
possesses a set of blocked signals, which can be modified using
Thread.sigmask . This set is inherited at thread creation time.
Per-thread signal masks are supported only by the system thread library
under Unix, but not under Win32, nor by the VM thread library.
val sigmask : Unix.sigprocmask_command -> int list -> int list
sigmask cmd sigs changes the set of blocked signals for the calling
thread. If cmd is SIG_SETMASK , blocked signals are set to those in
the list sigs . If cmd is SIG_BLOCK , the signals in sigs are added to
the set of blocked signals. If cmd is SIG_UNBLOCK , the signals in
sigs are removed from the set of blocked signals. sigmask returns the
set of previously blocked signals for the thread.
val wait_signal : int list -> int
wait_signal sigs suspends the execution of the calling thread until the
process receives one of the signals specified in the list sigs . It
then returns the number of the signal received. Signal handlers at-
tached to the signals in sigs will not be invoked. The signals sigs
are expected to be blocked before calling wait_signal .
OCamldoc 2023-02-12 Thread(3o)
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