diff options
Diffstat (limited to 'man3/pthread_cleanup_push.3')
| -rw-r--r-- | man3/pthread_cleanup_push.3 | 319 |
1 files changed, 0 insertions, 319 deletions
diff --git a/man3/pthread_cleanup_push.3 b/man3/pthread_cleanup_push.3 deleted file mode 100644 index eec8c8e..0000000 --- a/man3/pthread_cleanup_push.3 +++ /dev/null @@ -1,319 +0,0 @@ -'\" t -.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk -.\" <mtk.manpages@gmail.com> -.\" -.\" SPDX-License-Identifier: Linux-man-pages-copyleft -.\" -.TH pthread_cleanup_push 3 2023-10-31 "Linux man-pages 6.7" -.SH NAME -pthread_cleanup_push, pthread_cleanup_pop \- push and pop -thread cancelation clean-up handlers -.SH LIBRARY -POSIX threads library -.RI ( libpthread ", " \-lpthread ) -.SH SYNOPSIS -.nf -.B #include <pthread.h> -.P -.BI "void pthread_cleanup_push(void (*" routine ")(void *), void *" arg ); -.BI "void pthread_cleanup_pop(int " execute ); -.fi -.SH DESCRIPTION -These functions manipulate the calling thread's stack of -thread-cancelation clean-up handlers. -A clean-up handler is a function that is automatically executed -when a thread is canceled (or in various other circumstances -described below); -it might, for example, unlock a mutex so that -it becomes available to other threads in the process. -.P -The -.BR pthread_cleanup_push () -function pushes -.I routine -onto the top of the stack of clean-up handlers. -When -.I routine -is later invoked, it will be given -.I arg -as its argument. -.P -The -.BR pthread_cleanup_pop () -function removes the routine at the top of the stack of clean-up handlers, -and optionally executes it if -.I execute -is nonzero. -.P -A cancelation clean-up handler is popped from the stack -and executed in the following circumstances: -.IP \[bu] 3 -When a thread is canceled, -all of the stacked clean-up handlers are popped and executed in -the reverse of the order in which they were pushed onto the stack. -.IP \[bu] -When a thread terminates by calling -.BR pthread_exit (3), -all clean-up handlers are executed as described in the preceding point. -(Clean-up handlers are -.I not -called if the thread terminates by -performing a -.I return -from the thread start function.) -.IP \[bu] -When a thread calls -.BR pthread_cleanup_pop () -with a nonzero -.I execute -argument, the top-most clean-up handler is popped and executed. -.P -POSIX.1 permits -.BR pthread_cleanup_push () -and -.BR pthread_cleanup_pop () -to be implemented as macros that expand to text -containing \[aq]\fB{\fP\[aq] and \[aq]\fB}\fP\[aq], respectively. -For this reason, the caller must ensure that calls to these -functions are paired within the same function, -and at the same lexical nesting level. -(In other words, a clean-up handler is established only -during the execution of a specified section of code.) -.P -Calling -.BR longjmp (3) -.RB ( siglongjmp (3)) -produces undefined results if any call has been made to -.BR pthread_cleanup_push () -or -.BR pthread_cleanup_pop () -without the matching call of the pair since the jump buffer -was filled by -.BR setjmp (3) -.RB ( sigsetjmp (3)). -Likewise, calling -.BR longjmp (3) -.RB ( siglongjmp (3)) -from inside a clean-up handler produces undefined results -unless the jump buffer was also filled by -.BR setjmp (3) -.RB ( sigsetjmp (3)) -inside the handler. -.SH RETURN VALUE -These functions do not return a value. -.SH ERRORS -There are no errors. -.SH ATTRIBUTES -For an explanation of the terms used in this section, see -.BR attributes (7). -.TS -allbox; -lbx lb lb -l l l. -Interface Attribute Value -T{ -.na -.nh -.BR pthread_cleanup_push (), -.BR pthread_cleanup_pop () -T} Thread safety MT-Safe -.TE -.SH VERSIONS -On glibc, the -.BR pthread_cleanup_push () -and -.BR pthread_cleanup_pop () -functions -.I are -implemented as macros that expand to text -containing \[aq]\fB{\fP\[aq] and \[aq]\fB}\fP\[aq], respectively. -This means that variables declared within the scope of -paired calls to these functions will be visible within only that scope. -.P -POSIX.1 -.\" The text was actually added in the 2004 TC2 -says that the effect of using -.IR return , -.IR break , -.IR continue , -or -.I goto -to prematurely leave a block bracketed -.BR pthread_cleanup_push () -and -.BR pthread_cleanup_pop () -is undefined. -Portable applications should avoid doing this. -.SH STANDARDS -POSIX.1-2008. -.SH HISTORY -POSIX.1-2001. -glibc 2.0. -.SH EXAMPLES -The program below provides a simple example of the use of the functions -described in this page. -The program creates a thread that executes a loop bracketed by -.BR pthread_cleanup_push () -and -.BR pthread_cleanup_pop (). -This loop increments a global variable, -.IR cnt , -once each second. -Depending on what command-line arguments are supplied, -the main thread sends the other thread a cancelation request, -or sets a global variable that causes the other thread -to exit its loop and terminate normally (by doing a -.IR return ). -.P -In the following shell session, -the main thread sends a cancelation request to the other thread: -.P -.in +4n -.EX -$ \fB./a.out\fP -New thread started -cnt = 0 -cnt = 1 -Canceling thread -Called clean\-up handler -Thread was canceled; cnt = 0 -.EE -.in -.P -From the above, we see that the thread was canceled, -and that the cancelation clean-up handler was called -and it reset the value of the global variable -.I cnt -to 0. -.P -In the next run, the main program sets a -global variable that causes other thread to terminate normally: -.P -.in +4n -.EX -$ \fB./a.out x\fP -New thread started -cnt = 0 -cnt = 1 -Thread terminated normally; cnt = 2 -.EE -.in -.P -From the above, we see that the clean-up handler was not executed (because -.I cleanup_pop_arg -was 0), and therefore the value of -.I cnt -was not reset. -.P -In the next run, the main program sets a global variable that -causes the other thread to terminate normally, -and supplies a nonzero value for -.IR cleanup_pop_arg : -.P -.in +4n -.EX -$ \fB./a.out x 1\fP -New thread started -cnt = 0 -cnt = 1 -Called clean\-up handler -Thread terminated normally; cnt = 0 -.EE -.in -.P -In the above, we see that although the thread was not canceled, -the clean-up handler was executed, because the argument given to -.BR pthread_cleanup_pop () -was nonzero. -.SS Program source -\& -.\" SRC BEGIN (pthread_cleanup_push.c) -.EX -#include <errno.h> -#include <pthread.h> -#include <stdio.h> -#include <stdlib.h> -#include <sys/types.h> -#include <unistd.h> -\& -#define handle_error_en(en, msg) \e - do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0) -\& -static int done = 0; -static int cleanup_pop_arg = 0; -static int cnt = 0; -\& -static void -cleanup_handler(void *arg) -{ - printf("Called clean\-up handler\en"); - cnt = 0; -} -\& -static void * -thread_start(void *arg) -{ - time_t curr; -\& - printf("New thread started\en"); -\& - pthread_cleanup_push(cleanup_handler, NULL); -\& - curr = time(NULL); -\& - while (!done) { - pthread_testcancel(); /* A cancelation point */ - if (curr < time(NULL)) { - curr = time(NULL); - printf("cnt = %d\en", cnt); /* A cancelation point */ - cnt++; - } - } -\& - pthread_cleanup_pop(cleanup_pop_arg); - return NULL; -} -\& -int -main(int argc, char *argv[]) -{ - pthread_t thr; - int s; - void *res; -\& - s = pthread_create(&thr, NULL, thread_start, NULL); - if (s != 0) - handle_error_en(s, "pthread_create"); -\& - sleep(2); /* Allow new thread to run a while */ -\& - if (argc > 1) { - if (argc > 2) - cleanup_pop_arg = atoi(argv[2]); - done = 1; -\& - } else { - printf("Canceling thread\en"); - s = pthread_cancel(thr); - if (s != 0) - handle_error_en(s, "pthread_cancel"); - } -\& - s = pthread_join(thr, &res); - if (s != 0) - handle_error_en(s, "pthread_join"); -\& - if (res == PTHREAD_CANCELED) - printf("Thread was canceled; cnt = %d\en", cnt); - else - printf("Thread terminated normally; cnt = %d\en", cnt); - exit(EXIT_SUCCESS); -} -.EE -.\" SRC END -.SH SEE ALSO -.BR pthread_cancel (3), -.BR pthread_cleanup_push_defer_np (3), -.BR pthread_setcancelstate (3), -.BR pthread_testcancel (3), -.BR pthreads (7) |