Async-Interrupt-1.21/0000755000000000000000000000000012466727004013212 5ustar rootrootAsync-Interrupt-1.21/typemap0000644000000000000000000000020611230156305014576 0ustar rootrootasync_t * T_ASYNC s_epipe * T_EPIPE INPUT T_ASYNC $var = SvASYNC ($arg); T_EPIPE $var = INT2PTR (s_epipe *, SvIVX (SvRV ($arg))) Async-Interrupt-1.21/Makefile.PL0000644000000000000000000000071511226465560015166 0ustar rootrootuse ExtUtils::MakeMaker; use 5.008; # apparently PL_sighandlerp was introduced with 5.008 - correct me if wrong WriteMakefile( dist => { PREOP => 'pod2text Interrupt.pm | tee README >$(DISTVNAME)/README; chmod -R u=rwX,go=rX . ;', COMPRESS => 'gzip -9v', SUFFIX => '.gz', }, PREREQ_PM => { common::sense => 0, }, NAME => "Async::Interrupt", VERSION_FROM => "Interrupt.pm", ); Async-Interrupt-1.21/schmorp.h0000644000000000000000000002434412321667152015042 0ustar rootroot#ifndef SCHMORP_PERL_H_ #define SCHMORP_PERL_H_ /* WARNING * This header file is a shared resource between many modules. * perl header files MUST already be included. */ #include #include #if defined(WIN32 ) || defined(_MINIX) # define SCHMORP_H_PREFER_SELECT 1 #endif #if !SCHMORP_H_PREFER_SELECT # include #endif /* useful stuff, used by schmorp mostly */ #include "patchlevel.h" #define PERL_VERSION_ATLEAST(a,b,c) \ (PERL_REVISION > (a) \ || (PERL_REVISION == (a) \ && (PERL_VERSION > (b) \ || (PERL_VERSION == (b) && PERL_SUBVERSION >= (c))))) #ifndef PERL_MAGIC_ext # define PERL_MAGIC_ext '~' #endif #if !PERL_VERSION_ATLEAST (5,6,0) # ifndef PL_ppaddr # define PL_ppaddr ppaddr # endif # ifndef call_sv # define call_sv perl_call_sv # endif # ifndef get_sv # define get_sv perl_get_sv # endif # ifndef get_cv # define get_cv perl_get_cv # endif # ifndef IS_PADGV # define IS_PADGV(v) 0 # endif # ifndef IS_PADCONST # define IS_PADCONST(v) 0 # endif #endif /* use NV for 32 bit perls as it allows larger offsets */ #if IVSIZE >= 8 typedef IV VAL64; # define SvVAL64(sv) SvIV (sv) # define newSVval64(i64) newSViv (i64) #else typedef NV VAL64; # define SvVAL64(sv) SvNV (sv) # define newSVval64(i64) newSVnv (i64) #endif /* typemap for the above */ /* VAL64 T_VAL64 INPUT T_VAL64 $var = ($type)SvVAL64 ($arg); OUTPUT T_VAL64 $arg = newSVval64 ($var); */ /* 5.11 */ #ifndef CxHASARGS # define CxHASARGS(cx) (cx)->blk_sub.hasargs #endif /* 5.10.0 */ #ifndef SvREFCNT_inc_NN # define SvREFCNT_inc_NN(sv) SvREFCNT_inc (sv) #endif /* 5.8.8 */ #ifndef GV_NOTQUAL # define GV_NOTQUAL 0 #endif #ifndef newSV # define newSV(l) NEWSV(0,l) #endif #ifndef CvISXSUB_on # define CvISXSUB_on(cv) (void)cv #endif #ifndef CvISXSUB # define CvISXSUB(cv) (CvXSUB (cv) ? TRUE : FALSE) #endif #ifndef Newx # define Newx(ptr,nitems,type) New (0,ptr,nitems,type) #endif /* 5.8.7 */ #ifndef SvRV_set # define SvRV_set(s,v) SvRV(s) = (v) #endif static int s_signum (SV *sig) { #ifndef SIG_SIZE /* kudos to Slaven Rezic for the idea */ static char sig_size [] = { SIG_NUM }; # define SIG_SIZE (sizeof (sig_size) + 1) #endif dTHX; int signum; SvGETMAGIC (sig); for (signum = 1; signum < SIG_SIZE; ++signum) if (strEQ (SvPV_nolen (sig), PL_sig_name [signum])) return signum; signum = SvIV (sig); if (signum > 0 && signum < SIG_SIZE) return signum; return -1; } static int s_signum_croak (SV *sig) { int signum = s_signum (sig); if (signum < 0) { dTHX; croak ("%s: invalid signal name or number", SvPV_nolen (sig)); } return signum; } static int s_fileno (SV *fh, int wr) { dTHX; SvGETMAGIC (fh); if (SvROK (fh)) { fh = SvRV (fh); SvGETMAGIC (fh); } if (SvTYPE (fh) == SVt_PVGV) return PerlIO_fileno (wr ? IoOFP (sv_2io (fh)) : IoIFP (sv_2io (fh))); if (SvOK (fh) && (SvIV (fh) >= 0) && (SvIV (fh) < 0x7fffffffL)) return SvIV (fh); return -1; } static int s_fileno_croak (SV *fh, int wr) { int fd = s_fileno (fh, wr); if (fd < 0) { dTHX; croak ("%s: illegal fh argument, either not an OS file or read/write mode mismatch", SvPV_nolen (fh)); } return fd; } static SV * s_get_cv (SV *cb_sv) { dTHX; HV *st; GV *gvp; return (SV *)sv_2cv (cb_sv, &st, &gvp, 0); } static SV * s_get_cv_croak (SV *cb_sv) { SV *cv = s_get_cv (cb_sv); if (!cv) { dTHX; croak ("%s: callback must be a CODE reference or another callable object", SvPV_nolen (cb_sv)); } return cv; } /*****************************************************************************/ /* gensub: simple closure generation utility */ #define S_GENSUB_ARG CvXSUBANY (cv).any_ptr /* create a closure from XS, returns a code reference */ /* the arg can be accessed via GENSUB_ARG from the callback */ /* the callback must use dXSARGS/XSRETURN */ static SV * s_gensub (pTHX_ void (*xsub)(pTHX_ CV *), void *arg) { CV *cv = (CV *)newSV (0); sv_upgrade ((SV *)cv, SVt_PVCV); CvANON_on (cv); CvISXSUB_on (cv); CvXSUB (cv) = xsub; S_GENSUB_ARG = arg; return newRV_noinc ((SV *)cv); } /*****************************************************************************/ /* portable pipe/socketpair */ #if defined(USE_SOCKETS_AS_HANDLES) || PERL_VERSION_ATLEAST(5,18,0) # define S_TO_HANDLE(x) ((HANDLE)win32_get_osfhandle (x)) #else # define S_TO_HANDLE(x) ((HANDLE)x) #endif #ifdef _WIN32 /* taken almost verbatim from libev's ev_win32.c */ /* oh, the humanity! */ static int s_pipe (int filedes [2]) { dTHX; struct sockaddr_in addr = { 0 }; int addr_size = sizeof (addr); struct sockaddr_in adr2; int adr2_size = sizeof (adr2); SOCKET listener; SOCKET sock [2] = { -1, -1 }; if ((listener = socket (AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) return -1; addr.sin_family = AF_INET; addr.sin_addr.s_addr = htonl (INADDR_LOOPBACK); addr.sin_port = 0; if (bind (listener, (struct sockaddr *)&addr, addr_size)) goto fail; if (getsockname (listener, (struct sockaddr *)&addr, &addr_size)) goto fail; if (listen (listener, 1)) goto fail; if ((sock [0] = socket (AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) goto fail; if (connect (sock [0], (struct sockaddr *)&addr, addr_size)) goto fail; if ((sock [1] = accept (listener, 0, 0)) < 0) goto fail; /* windows vista returns fantasy port numbers for getpeername. * example for two interconnected tcp sockets: * * (Socket::unpack_sockaddr_in getsockname $sock0)[0] == 53364 * (Socket::unpack_sockaddr_in getpeername $sock0)[0] == 53363 * (Socket::unpack_sockaddr_in getsockname $sock1)[0] == 53363 * (Socket::unpack_sockaddr_in getpeername $sock1)[0] == 53365 * * wow! tridirectional sockets! * * this way of checking ports seems to work: */ if (getpeername (sock [0], (struct sockaddr *)&addr, &addr_size)) goto fail; if (getsockname (sock [1], (struct sockaddr *)&adr2, &adr2_size)) goto fail; errno = WSAEINVAL; if (addr_size != adr2_size || addr.sin_addr.s_addr != adr2.sin_addr.s_addr /* just to be sure, I mean, it's windows */ || addr.sin_port != adr2.sin_port) goto fail; closesocket (listener); #ifdef USE_SOCKETS_AS_HANDLES /* when select isn't winsocket, we also expect socket, connect, accept etc. * to work on fds */ filedes [0] = sock [0]; filedes [1] = sock [1]; #else filedes [0] = _open_osfhandle (sock [0], 0); filedes [1] = _open_osfhandle (sock [1], 0); #endif return 0; fail: closesocket (listener); if (sock [0] != INVALID_SOCKET) closesocket (sock [0]); if (sock [1] != INVALID_SOCKET) closesocket (sock [1]); return -1; } #define s_socketpair(domain,type,protocol,filedes) s_pipe (filedes) static int s_fd_blocking (int fd, int blocking) { u_long nonblocking = !blocking; return ioctlsocket ((SOCKET)S_TO_HANDLE (fd), FIONBIO, &nonblocking); } #define s_fd_prepare(fd) s_fd_blocking (fd, 0) #else #define s_socketpair(domain,type,protocol,filedes) socketpair (domain, type, protocol, filedes) #define s_pipe(filedes) pipe (filedes) static int s_fd_blocking (int fd, int blocking) { return fcntl (fd, F_SETFL, blocking ? 0 : O_NONBLOCK); } static int s_fd_prepare (int fd) { return s_fd_blocking (fd, 0) || fcntl (fd, F_SETFD, FD_CLOEXEC); } #endif #if __linux && (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 7)) # define SCHMORP_H_HAVE_EVENTFD 1 /* our minimum requirement is glibc 2.7 which has the stub, but not the header */ # include # ifdef __cplusplus extern "C" { # endif int eventfd (unsigned int initval, int flags); # ifdef __cplusplus } # endif #else # define eventfd(initval,flags) -1 #endif typedef struct { int fd[2]; /* read, write fd, might be equal */ int len; /* write length (1 pipe/socket, 8 eventfd) */ } s_epipe; static int s_epipe_new (s_epipe *epp) { s_epipe ep; ep.fd [0] = ep.fd [1] = eventfd (0, 0); if (ep.fd [0] >= 0) { s_fd_prepare (ep.fd [0]); ep.len = 8; } else { if (s_pipe (ep.fd)) return -1; if (s_fd_prepare (ep.fd [0]) || s_fd_prepare (ep.fd [1])) { dTHX; close (ep.fd [0]); close (ep.fd [1]); return -1; } ep.len = 1; } *epp = ep; return 0; } static void s_epipe_destroy (s_epipe *epp) { dTHX; close (epp->fd [0]); if (epp->fd [1] != epp->fd [0]) close (epp->fd [1]); epp->len = 0; } static void s_epipe_signal (s_epipe *epp) { #ifdef _WIN32 /* perl overrides send with a function that crashes in other threads. * unfortunately, it overrides it with an argument-less macro, so * there is no way to force usage of the real send function. * incompetent windows programmers - is this redundant? */ DWORD dummy; WriteFile (S_TO_HANDLE (epp->fd [1]), (LPCVOID)&dummy, 1, &dummy, 0); #else # if SCHMORP_H_HAVE_EVENTFD static uint64_t counter = 1; # else static char counter [8]; # endif /* some modules accept fd's from outside, support eventfd here */ if (write (epp->fd [1], &counter, epp->len) < 0 && errno == EINVAL && epp->len != 8) write (epp->fd [1], &counter, (epp->len = 8)); #endif } static void s_epipe_drain (s_epipe *epp) { dTHX; char buf [9]; #ifdef _WIN32 recv (epp->fd [0], buf, sizeof (buf), 0); #else read (epp->fd [0], buf, sizeof (buf)); #endif } /* like new, but dups over old */ static int s_epipe_renew (s_epipe *epp) { dTHX; s_epipe epn; if (epp->fd [1] != epp->fd [0]) close (epp->fd [1]); if (s_epipe_new (&epn)) return -1; if (epp->len) { if (dup2 (epn.fd [0], epp->fd [0]) < 0) croak ("unable to dup over old event pipe"); /* should not croak */ close (epn.fd [0]); if (epn.fd [0] == epn.fd [1]) epn.fd [1] = epp->fd [0]; epn.fd [0] = epp->fd [0]; } *epp = epn; return 0; } #define s_epipe_fd(epp) ((epp)->fd [0]) static int s_epipe_wait (s_epipe *epp) { dTHX; #if SCHMORP_H_PREFER_SELECT fd_set rfd; int fd = s_epipe_fd (epp); FD_ZERO (&rfd); FD_SET (fd, &rfd); return PerlSock_select (fd + 1, &rfd, 0, 0, 0); #else /* poll is preferable on posix systems */ struct pollfd pfd; pfd.fd = s_epipe_fd (epp); pfd.events = POLLIN; return poll (&pfd, 1, -1); #endif } #endif Async-Interrupt-1.21/META.yml0000644000000000000000000000070712466727004014467 0ustar rootroot--- abstract: unknown author: - unknown build_requires: ExtUtils::MakeMaker: '0' configure_requires: ExtUtils::MakeMaker: '0' dynamic_config: 1 generated_by: 'ExtUtils::MakeMaker version 6.98, CPAN::Meta::Converter version 2.142060' license: unknown meta-spec: url: http://module-build.sourceforge.net/META-spec-v1.4.html version: '1.4' name: Async-Interrupt no_index: directory: - t - inc requires: common::sense: '0' version: 1.21 Async-Interrupt-1.21/Changes0000644000000000000000000000601112466726772014516 0ustar rootrootRevision history for Perl extension Async::Interrupt. 1.21 Wed Feb 11 20:31:01 CET 2015 - upgrade ecb.h for C11 compatibility. 1.2 Fri Apr 11 06:22:38 CEST 2014 - perl5porters broke Async::Interrupt, BDB, EV, IO::AIO, OpenCL without warning by switching the meaning of USE_SOCKETS_AS_HANDLES in 5.18. What's so attractive about giving a shit about backwards compatibility - I will never understand. 1.1 Wed Apr 25 00:46:08 CEST 2012 - new $async->handle method. - new $async->pipe_drain method. - use memory fences for !x86, and x86 future proofing. use libecb for implementation. 1.05 Sat May 15 02:06:33 CEST 2010 - implement $epipe->signal_func method. 1.04 Wed Mar 31 02:46:49 CEST 2010 - a double fork partially killed the event pipe (great testcase by dormando). affects IO::AIO, BDB and Async::Interrupt. 1.03 Tue Nov 24 14:31:10 CET 2009 - port to loser platform. 1.02 Tue Sep 1 18:41:09 CEST 2009 - prototypes for sig2name/sig2num were missing. 1.01 Wed Aug 5 13:50:59 CEST 2009 - evpipe->wait did immediately return on !windows. 1.0 Thu Jul 30 05:58:55 CEST 2009 - implement signal_hysteresis. - implement scope_block_func. - implement sig2name/sig2num convenience functions. 0.6 Sat Jul 18 07:09:33 CEST 2009 - add autodrain setting. - added Async::Interrupt::EventPipe class. - fixed a potential race issue by removing the internal epipe state. - destroying asyncs inside their handler callback could lead to segfaults. - destroying an interrupt object did not properly remove it from the asyncs list (classical case of side-effect-inside-assert). 0.501 Fri Jul 17 16:58:51 CEST 2009 - do no longer errornously do operations on fd 0 if no pipe is associated with the interrupt object. 0.5 Fri Jul 17 03:53:21 CEST 2009 - INCOMPATIBLE CHANGE: signalling the value 0 is no longer allowed. - added automatic pipe creation code, including post_fork method. - added ->c_var method, and the ability to use a perl scalar as signal checker. 0.042 Tue Jul 14 21:51:04 CEST 2009 - enforce initialisation of perl's signal handling framework, avoiding crashes otherwise. - switched to common::sense. - freely sprinkle around more volatiles. - fix initialisation code (XSLoader). - ported to win32. 0.041 Sun Jul 12 18:32:46 CEST 2009 - oh my, I forgot to include the typemap. - improved documentation. 0.04 Sun Jul 12 00:24:02 CEST 2009 - added ability to block the pipe write temporarily. - added the ability to call signal when the process receives a (POSIX) signal. - removed debugging output in constructor. - support eventfd instead of a pipe (untested). 0.03 Fri Jul 3 23:11:05 CEST 2009 - port to perl <= 5.8.9. 0.02 Thu Jul 2 17:17:30 CEST 2009 - first release, rather untested. 0.01 Thu Jul 2 13:18:00 CEST 2009 - original version; cloned from Convert::Scalar. Async-Interrupt-1.21/META.json0000644000000000000000000000150312466727004014632 0ustar rootroot{ "abstract" : "unknown", "author" : [ "unknown" ], "dynamic_config" : 1, "generated_by" : "ExtUtils::MakeMaker version 6.98, CPAN::Meta::Converter version 2.142060", "license" : [ "unknown" ], "meta-spec" : { "url" : "http://search.cpan.org/perldoc?CPAN::Meta::Spec", "version" : "2" }, "name" : "Async-Interrupt", "no_index" : { "directory" : [ "t", "inc" ] }, "prereqs" : { "build" : { "requires" : { "ExtUtils::MakeMaker" : "0" } }, "configure" : { "requires" : { "ExtUtils::MakeMaker" : "0" } }, "runtime" : { "requires" : { "common::sense" : "0" } } }, "release_status" : "stable", "version" : 1.21 } Async-Interrupt-1.21/COPYING0000644000000000000000000000007610431374667014253 0ustar rootrootThis module is licensed under the same terms as perl itself. Async-Interrupt-1.21/README0000644000000000000000000005624612466727004014107 0ustar rootrootNAME Async::Interrupt - allow C/XS libraries to interrupt perl asynchronously SYNOPSIS use Async::Interrupt; DESCRIPTION This module implements a single feature only of interest to advanced perl modules, namely asynchronous interruptions (think "UNIX signals", which are very similar). Sometimes, modules wish to run code asynchronously (in another thread, or from a signal handler), and then signal the perl interpreter on certain events. One common way is to write some data to a pipe and use an event handling toolkit to watch for I/O events. Another way is to send a signal. Those methods are slow, and in the case of a pipe, also not asynchronous - it won't interrupt a running perl interpreter. This module implements asynchronous notifications that enable you to signal running perl code from another thread, asynchronously, and sometimes even without using a single syscall. USAGE SCENARIOS Race-free signal handling There seems to be no way to do race-free signal handling in perl: to catch a signal, you have to execute Perl code, and between entering the interpreter "select" function (or other blocking functions) and executing the select syscall is a small but relevant timespan during which signals will be queued, but perl signal handlers will not be executed and the blocking syscall will not be interrupted. You can use this module to bind a signal to a callback while at the same time activating an event pipe that you can "select" on, fixing the race completely. This can be used to implement the signal hadling in event loops, e.g. AnyEvent, POE, IO::Async::Loop and so on. Background threads want speedy reporting Assume you want very exact timing, and you can spare an extra cpu core for that. Then you can run an extra thread that signals your perl interpreter. This means you can get a very exact timing source while your perl code is number crunching, without even using a syscall to communicate between your threads. For example the deliantra game server uses a variant of this technique to interrupt background processes regularly to send map updates to game clients. Or EV::Loop::Async uses an interrupt object to wake up perl when new events have arrived. IO::AIO and BDB could also use this to speed up result reporting. Speedy event loop invocation One could use this module e.g. in Coro to interrupt a running coro-thread and cause it to enter the event loop. Or one could bind to "SIGIO" and tell some important sockets to send this signal, causing the event loop to be entered to reduce network latency. HOW TO USE You can use this module by creating an "Async::Interrupt" object for each such event source. This object stores a perl and/or a C-level callback that is invoked when the "Async::Interrupt" object gets signalled. It is executed at the next time the perl interpreter is running (i.e. it will interrupt a computation, but not an XS function or a syscall). You can signal the "Async::Interrupt" object either by calling it's "->signal" method, or, more commonly, by calling a C function. There is also the built-in (POSIX) signal source. The "->signal_func" returns the address of the C function that is to be called (plus an argument to be used during the call). The signalling function also takes an integer argument in the range SIG_ATOMIC_MIN to SIG_ATOMIC_MAX (guaranteed to allow at least 0..127). Since this kind of interruption is fast, but can only interrupt a *running* interpreter, there is optional support for signalling a pipe - that means you can also wait for the pipe to become readable (e.g. via EV or AnyEvent). This, of course, incurs the overhead of a "read" and "write" syscall. USAGE EXAMPLES Implementing race-free signal handling This example uses a single event pipe for all signals, and one Async::Interrupt per signal. This code is actually what the AnyEvent module uses itself when Async::Interrupt is available. First, create the event pipe and hook it into the event loop $SIGPIPE = new Async::Interrupt::EventPipe; $SIGPIPE_W = AnyEvent->io ( fh => $SIGPIPE->fileno, poll => "r", cb => \&_signal_check, # defined later ); Then, for each signal to hook, create an Async::Interrupt object. The callback just sets a global variable, as we are only interested in synchronous signals (i.e. when the event loop polls), which is why the pipe draining is not done automatically. my $interrupt = new Async::Interrupt cb => sub { undef $SIGNAL_RECEIVED{$signum} }, signal => $signum, pipe => [$SIGPIPE->filenos], pipe_autodrain => 0, ; Finally, the I/O callback for the event pipe handles the signals: sub _signal_check { # drain the pipe first $SIGPIPE->drain; # two loops, just to be sure while (%SIGNAL_RECEIVED) { for (keys %SIGNAL_RECEIVED) { delete $SIGNAL_RECEIVED{$_}; warn "signal $_ received\n"; } } } Interrupt perl from another thread This example interrupts the Perl interpreter from another thread, via the XS API. This is used by e.g. the EV::Loop::Async module. On the Perl level, a new loop object (which contains the thread) is created, by first calling some XS constructor, querying the C-level callback function and feeding that as the "c_cb" into the Async::Interrupt constructor: my $self = XS_thread_constructor; my ($c_func, $c_arg) = _c_func $self; # return the c callback my $asy = new Async::Interrupt c_cb => [$c_func, $c_arg]; Then the newly created Interrupt object is queried for the signaling function that the newly created thread should call, and this is in turn told to the thread object: _attach $self, $asy->signal_func; So to repeat: first the XS object is created, then it is queried for the callback that should be called when the Interrupt object gets signalled. Then the interrupt object is queried for the callback fucntion that the thread should call to signal the Interrupt object, and this callback is then attached to the thread. You have to be careful that your new thread is not signalling before the signal function was configured, for example by starting the background thread only within "_attach". That concludes the Perl part. The XS part consists of the actual constructor which creates a thread, which is not relevant for this example, and two functions, "_c_func", which returns the Perl-side callback, and "_attach", which configures the signalling functioon that is safe toc all from another thread. For simplicity, we will use global variables to store the functions, normally you would somehow attach them to $self. The "c_func" simply returns the address of a static function and arranges for the object pointed to by $self to be passed to it, as an integer: void _c_func (SV *loop) PPCODE: EXTEND (SP, 2); PUSHs (sv_2mortal (newSViv (PTR2IV (c_func)))); PUSHs (sv_2mortal (newSViv (SvRV (loop)))); This would be the callback (since it runs in a normal Perl context, it is permissible to manipulate Perl values): static void c_func (pTHX_ void *loop_, int value) { SV *loop_object = (SV *)loop_; ... } And this attaches the signalling callback: static void (*my_sig_func) (void *signal_arg, int value); static void *my_sig_arg; void _attach (SV *loop_, IV sig_func, void *sig_arg) CODE: { my_sig_func = sig_func; my_sig_arg = sig_arg; /* now run the thread */ thread_create (&u->tid, l_run, 0); } And "l_run" (the background thread) would eventually call the signaling function: my_sig_func (my_sig_arg, 0); You can have a look at EV::Loop::Async for an actual example using intra-thread communication, locking and so on. THE Async::Interrupt CLASS $async = new Async::Interrupt key => value... Creates a new Async::Interrupt object. You may only use async notifications on this object while it exists, so you need to keep a reference to it at all times while it is used. Optional constructor arguments include (normally you would specify at least one of "cb" or "c_cb"). cb => $coderef->($value) Registers a perl callback to be invoked whenever the async interrupt is signalled. Note that, since this callback can be invoked at basically any time, it must not modify any well-known global variables such as $/ without restoring them again before returning. The exceptions are $! and $@, which are saved and restored by Async::Interrupt. If the callback should throw an exception, then it will be caught, and $Async::Interrupt::DIED will be called with $@ containing the exception. The default will simply "warn" about the message and continue. c_cb => [$c_func, $c_arg] Registers a C callback the be invoked whenever the async interrupt is signalled. The C callback must have the following prototype: void c_func (pTHX_ void *c_arg, int value); Both $c_func and $c_arg must be specified as integers/IVs, and $value is the "value" passed to some earlier call to either $signal or the "signal_func" function. Note that, because the callback can be invoked at almost any time, you have to be careful at saving and restoring global variables that Perl might use (the exception is "errno", which is saved and restored by Async::Interrupt). The callback itself runs as part of the perl context, so you can call any perl functions and modify any perl data structures (in which case the requirements set out for "cb" apply as well). var => $scalar_ref When specified, then the given argument must be a reference to a scalar. The scalar will be set to 0 initially. Signalling the interrupt object will set it to the passed value, handling the interrupt will reset it to 0 again. Note that the only thing you are legally allowed to do is to is to check the variable in a boolean or integer context (e.g. comparing it with a string, or printing it, will *destroy* it and might cause your program to crash or worse). signal => $signame_or_value When this parameter is specified, then the Async::Interrupt will hook the given signal, that is, it will effectively call "->signal (0)" each time the given signal is caught by the process. Only one async can hook a given signal, and the signal will be restored to defaults when the Async::Interrupt object gets destroyed. signal_hysteresis => $boolean Sets the initial signal hysteresis state, see the "signal_hysteresis" method, below. pipe => [$fileno_or_fh_for_reading, $fileno_or_fh_for_writing] Specifies two file descriptors (or file handles) that should be signalled whenever the async interrupt is signalled. This means a single octet will be written to it, and before the callback is being invoked, it will be read again. Due to races, it is unlikely but possible that multiple octets are written. It is required that the file handles are both in nonblocking mode. The object will keep a reference to the file handles. This can be used to ensure that async notifications will interrupt event frameworks as well. Note that "Async::Interrupt" will create a suitable signal fd automatically when your program requests one, so you don't have to specify this argument when all you want is an extra file descriptor to watch. If you want to share a single event pipe between multiple Async::Interrupt objects, you can use the "Async::Interrupt::EventPipe" class to manage those. pipe_autodrain => $boolean Sets the initial autodrain state, see the "pipe_autodrain" method, below. ($signal_func, $signal_arg) = $async->signal_func Returns the address of a function to call asynchronously. The function has the following prototype and needs to be passed the specified $signal_arg, which is a "void *" cast to "IV": void (*signal_func) (void *signal_arg, int value) An example call would look like: signal_func (signal_arg, 0); The function is safe to call from within signal and thread contexts, at any time. The specified "value" is passed to both C and Perl callback. $value must be in the valid range for a "sig_atomic_t", except 0 (1..127 is portable). If the function is called while the Async::Interrupt object is already signaled but before the callbacks are being executed, then the stored "value" is either the old or the new one. Due to the asynchronous nature of the code, the "value" can even be passed to two consecutive invocations of the callback. $address = $async->c_var Returns the address (cast to IV) of an "IV" variable. The variable is set to 0 initially and gets set to the passed value whenever the object gets signalled, and reset to 0 once the interrupt has been handled. Note that it is often beneficial to just call "PERL_ASYNC_CHECK ()" to handle any interrupts. Example: call some XS function to store the address, then show C code waiting for it. my_xs_func $async->c_var; static IV *valuep; void my_xs_func (void *addr) CODE: valuep = (IV *)addr; // code in a loop, waiting while (!*valuep) ; // do something $async->signal ($value=1) This signals the given async object from Perl code. Semi-obviously, this will instantly trigger the callback invocation (it does not, as the name might imply, do anything with POSIX signals). $value must be in the valid range for a "sig_atomic_t", except 0 (1..127 is portable). $async->handle Calls the callback if the object is pending. This method does not need to be called normally, as it will be invoked automatically. However, it can be used to force handling of outstanding interrupts while the object is blocked. One reason why one might want to do that is when you want to switch from asynchronous interruptions to synchronous one, using e.g. an event loop. To do that, one would first "$async->block" the interrupt object, then register a read watcher on the "pipe_fileno" that calls "$async->handle". This disables asynchronous interruptions, but ensures that interrupts are handled by the event loop. $async->signal_hysteresis ($enable) Enables or disables signal hysteresis (default: disabled). If a POSIX signal is used as a signal source for the interrupt object, then enabling signal hysteresis causes Async::Interrupt to reset the signal action to "SIG_IGN" in the signal handler and restore it just before handling the interruption. When you expect a lot of signals (e.g. when using SIGIO), then enabling signal hysteresis can reduce the number of handler invocations considerably, at the cost of two extra syscalls. Note that setting the signal to "SIG_IGN" can have unintended side effects when you fork and exec other programs, as often they do not expect signals to be ignored by default. $async->block $async->unblock Sometimes you need a "critical section" of code that will not be interrupted by an Async::Interrupt. This can be implemented by calling "$async->block" before the critical section, and "$async->unblock" afterwards. Note that there must be exactly one call of "unblock" for every previous call to "block" (i.e. calls can nest). Since ensuring this in the presence of exceptions and threads is usually more difficult than you imagine, I recommend using "$async->scoped_block" instead. $async->scope_block This call "$async->block" and installs a handler that is called when the current scope is exited (via an exception, by canceling the Coro thread, by calling last/goto etc.). This is the recommended (and fastest) way to implement critical sections. ($block_func, $block_arg) = $async->scope_block_func Returns the address of a function that implements the "scope_block" functionality. It has the following prototype and needs to be passed the specified $block_arg, which is a "void *" cast to "IV": void (*block_func) (void *block_arg) An example call would look like: block_func (block_arg); The function is safe to call only from within the toplevel of a perl XS function and will call "LEAVE" and "ENTER" (in this order!). $async->pipe_enable $async->pipe_disable Enable/disable signalling the pipe when the interrupt occurs (default is enabled). Writing to a pipe is relatively expensive, so it can be disabled when you know you are not waiting for it (for example, with EV you could disable the pipe in a check watcher, and enable it in a prepare watcher). Note that currently, while "pipe_disable" is in effect, no attempt to read from the pipe will be done when handling events. This might change as soon as I realize why this is a mistake. $fileno = $async->pipe_fileno Returns the reading side of the signalling pipe. If no signalling pipe is currently attached to the object, it will dynamically create one. Note that the only valid operation on this file descriptor is to wait until it is readable. The fd might belong currently to a pipe, a tcp socket, or an eventfd, depending on the platform, and is guaranteed to be "select"able. $async->pipe_autodrain ($enable) Enables (1) or disables (0) automatic draining of the pipe (default: enabled). When automatic draining is enabled, then Async::Interrupt will automatically clear the pipe. Otherwise the user is responsible for this draining. This is useful when you want to share one pipe among many Async::Interrupt objects. $async->pipe_drain Drains the pipe manually, for example, when autodrain is disabled. Does nothing when no pipe is enabled. $async->post_fork The object will not normally be usable after a fork (as the pipe fd is shared between processes). Calling this method after a fork in the child ensures that the object will work as expected again. It only needs to be called when the async object is used in the child. This only works when the pipe was created by Async::Interrupt. Async::Interrupt ensures that the reading file descriptor does not change it's value. $signum = Async::Interrupt::sig2num $signame_or_number $signame = Async::Interrupt::sig2name $signame_or_number These two convenience functions simply convert a signal name or number to the corresponding name or number. They are not used by this module and exist just because perl doesn't have a nice way to do this on its own. They will return "undef" on illegal names or numbers. THE Async::Interrupt::EventPipe CLASS Pipes are the predominant utility to make asynchronous signals synchronous. However, pipes are hard to come by: they don't exist on the broken windows platform, and on GNU/Linux systems, you might want to use an "eventfd" instead. This class creates selectable event pipes in a portable fashion: on windows, it will try to create a tcp socket pair, on GNU/Linux, it will try to create an eventfd and everywhere else it will try to use a normal pipe. $epipe = new Async::Interrupt::EventPipe This creates and returns an eventpipe object. This object is simply a blessed array reference: ($r_fd, $w_fd) = $epipe->filenos Returns the read-side file descriptor and the write-side file descriptor. Example: pass an eventpipe object as pipe to the Async::Interrupt constructor, and create an AnyEvent watcher for the read side. my $epipe = new Async::Interrupt::EventPipe; my $asy = new Async::Interrupt pipe => [$epipe->filenos]; my $iow = AnyEvent->io (fh => $epipe->fileno, poll => 'r', cb => sub { }); $r_fd = $epipe->fileno Return only the reading/listening side. $epipe->signal Write something to the pipe, in a portable fashion. $epipe->drain Drain (empty) the pipe. ($c_func, $c_arg) = $epipe->signal_func ($c_func, $c_arg) = $epipe->drain_func These two methods returns a function pointer and "void *" argument that can be called to have the effect of "$epipe->signal" or "$epipe->drain", respectively, on the XS level. They both have the following prototype and need to be passed their $c_arg, which is a "void *" cast to an "IV": void (*c_func) (void *c_arg) An example call would look like: c_func (c_arg); $epipe->renew Recreates the pipe (useful after a fork). The reading side will not change it's file descriptor number, but the writing side might. $epipe->wait This method blocks the process until there are events on the pipe. This is not a very event-based or ncie way of usign an event pipe, but it can be occasionally useful. IMPLEMENTATION DETAILS AND LIMITATIONS This module works by "hijacking" SIGKILL, which is guaranteed to always exist, but also cannot be caught, so is always available. Basically, this module fakes the occurance of a SIGKILL signal and then intercepts the interpreter handling it. This makes normal signal handling slower (probably unmeasurably, though), but has the advantage of not requiring a special runops function, nor slowing down normal perl execution a bit. It assumes that "sig_atomic_t", "int" and "IV" are all async-safe to modify. AUTHOR Marc Lehmann http://home.schmorp.de/ Async-Interrupt-1.21/t/0000755000000000000000000000000012466727004013455 5ustar rootrootAsync-Interrupt-1.21/t/03_signal.t0000644000000000000000000000076711233451105015416 0ustar rootrootunless (exists $SIG{USR1}) { print "1..0 # SKIP no SIGUSR1 - broken platform, skipping tests\n"; exit; } print "1..9\n"; $|=1; use Async::Interrupt; my $three = 3; my $ai = new Async::Interrupt cb => sub { print "ok ", $three++, "\n" }, signal => "CHLD"; print "ok 1\n"; { $ai->scope_block; $ai->scope_block; kill CHLD => $$; print "ok 2\n"; } kill CHLD, $$; $ai->signal_hysteresis (1); kill CHLD, $$; kill CHLD, $$; kill CHLD, $$; kill CHLD, $$; print "ok 9\n"; Async-Interrupt-1.21/t/00_load.t0000644000000000000000000000017611223114451015046 0ustar rootrootBEGIN { $| = 1; print "1..1\n"; } END {print "not ok 1\n" unless $loaded;} use Async::Interrupt; $loaded = 1; print "ok 1\n"; Async-Interrupt-1.21/t/02_pipe.t0000644000000000000000000000223611226205764015100 0ustar rootroot#! perl no warnings; use Socket; my ($pr, $pw); unless (socketpair $pr, $pw, Socket::AF_UNIX (), Socket::SOCK_STREAM (), 0) { print "1..0 # SKIP socketpair failed - broken platform, skipping tests\n"; exit; } print "1..12\n"; $|=1; use Async::Interrupt; # we ignore the requirement to put handles into nonblocking mode # IN THIS TEST only. never do that in real life. my $ai = new Async::Interrupt pipe => [$pr, $pw], cb => sub { print "ok $_[0]\n" }; print "ok 1\n"; $ai->signal (2); print "ok 3\n"; my ($vr, $vR); vec ($vr, fileno $pr, 1) = 1; my $n = select $vR=$vr, undef, undef, 0; print $n == 0 ? "" : "not ", "ok 4 # $n\n"; $ai->block; $ai->signal (7); print "ok 5\n"; my $n = select $vR=$vr, undef, undef, 0; print $n == 1 ? "" : "not ", "ok 6 # $n\n"; $ai->unblock; my $n = select $vR=$vr, undef, undef, 0; print $n == 0 ? "" : "not ", "ok 8 # $n\n"; $ai->signal (9); my $n = select $vR=$vr, undef, undef, 0; print $n == 0 ? "" : "not ", "ok 10 # $n\n"; $ai->pipe_disable; $ai->scope_block; $ai->signal (12); my $n = select $vR=$vr, undef, undef, 0; print $n == 0 ? "" : "not ", "ok 11 # $n\n"; undef $ai; # will cause signal to be sent Async-Interrupt-1.21/t/05_var.t0000644000000000000000000000063411227754440014737 0ustar rootrootprint "1..7\n"; $|=1; use Async::Interrupt; my $var; my $ai = new Async::Interrupt var => \$var, cb => sub { print $var ? "not " : "", "ok $_[0]\n" }; print $$ai ? "" : "not ", "ok 1 # $$ai\n"; print $ai->c_var ? "" : "not ", "ok 2\n"; $ai->signal (3); print $var == 0 ? "" : "not ", "ok 4\n"; $ai->block; $ai->signal (7); print "ok 5\n"; print $var == 7 ? "" : "not ", "ok 6\n"; $ai->unblock; Async-Interrupt-1.21/t/06_epipe.t0000644000000000000000000000110211373362762015245 0ustar rootroot#! perl no warnings; print "1..6\n"; $|=1; use Async::Interrupt; my $ep = new Async::Interrupt::EventPipe; my $fd = $ep->fileno; print "ok 1\n"; my ($vr, $vR); vec ($vr, $fd, 1) = 1; my $n = select $vR=$vr, undef, undef, 0; print $n == 0 ? "" : "not ", "ok 2 # $n\n"; $ep->signal; my $n = select $vR=$vr, undef, undef, 0; print $n == 1 ? "" : "not ", "ok 3 # $n\n"; $ep->drain; my $n = select $vR=$vr, undef, undef, 0; print $n == 0 ? "" : "not ", "ok 4 # $n\n"; print "ok 5 # ", join " ", $ep->signal_func, "\n"; print "ok 6 # ", join " ", $ep->drain_func, "\n"; Async-Interrupt-1.21/t/04_apipe.t0000644000000000000000000000200011227750114015223 0ustar rootroot#! perl no warnings; print "1..14\n"; $|=1; use Async::Interrupt; my $ai = new Async::Interrupt cb => sub { print "ok $_[0]\n" }; my $fd = $ai->pipe_fileno; print "ok 1\n"; $ai->signal (2); print "ok 3\n"; my ($vr, $vR); vec ($vr, $ai->pipe_fileno, 1) = 1; my $n = select $vR=$vr, undef, undef, 0; print $n == 0 ? "" : "not ", "ok 4 # $n\n"; $ai->block; $ai->signal (7); print "ok 5\n"; my $n = select $vR=$vr, undef, undef, 0; print $n == 1 ? "" : "not ", "ok 6 # $n\n"; $ai->unblock; my $n = select $vR=$vr, undef, undef, 0; print $n == 0 ? "" : "not ", "ok 8 # $n\n"; $ai->signal (9); my $n = select $vR=$vr, undef, undef, 0; print $n == 0 ? "" : "not ", "ok 10 # $n\n"; $ai->pipe_disable; $ai->scope_block; $ai->signal (14); my $n = select $vR=$vr, undef, undef, 0; print $n == 0 ? "" : "not ", "ok 11 # $n\n"; $ai->post_fork; print $fd == $ai->pipe_fileno ? "" : "not ", "ok 12\n"; $ai->post_fork; print $fd == $ai->pipe_fileno ? "" : "not ", "ok 13\n"; undef $ai; # will cause signal to be sent Async-Interrupt-1.21/t/01_basic.t0000644000000000000000000000106211223156162015211 0ustar rootrootprint "1..12\n"; $|=1; use Async::Interrupt; my $ai = new Async::Interrupt cb => sub { print "ok $_[0]\n" }; my $ai2 = new Async::Interrupt; print $$ai ? "" : "not ", "ok 1 # $$ai\n"; my ($a, $b) = $ai->signal_func; print $a ? "" : "not ", "ok 2 # $a\n"; print $b ? "" : "not ", "ok 3 # $b\n"; $ai->signal (4); my $ai3 = new Async::Interrupt; print "ok 5\n"; $ai->block; $ai->signal (7); print "ok 6\n"; $ai->unblock; print "ok 8\n"; undef $ai2; print "ok 9\n"; { $ai->scope_block; $ai->signal (11); print "ok 10\n"; } print "ok 12\n"; Async-Interrupt-1.21/Interrupt.pm0000644000000000000000000005323712466727000015552 0ustar rootroot=head1 NAME Async::Interrupt - allow C/XS libraries to interrupt perl asynchronously =head1 SYNOPSIS use Async::Interrupt; =head1 DESCRIPTION This module implements a single feature only of interest to advanced perl modules, namely asynchronous interruptions (think "UNIX signals", which are very similar). Sometimes, modules wish to run code asynchronously (in another thread, or from a signal handler), and then signal the perl interpreter on certain events. One common way is to write some data to a pipe and use an event handling toolkit to watch for I/O events. Another way is to send a signal. Those methods are slow, and in the case of a pipe, also not asynchronous - it won't interrupt a running perl interpreter. This module implements asynchronous notifications that enable you to signal running perl code from another thread, asynchronously, and sometimes even without using a single syscall. =head2 USAGE SCENARIOS =over 4 =item Race-free signal handling There seems to be no way to do race-free signal handling in perl: to catch a signal, you have to execute Perl code, and between entering the interpreter C on, fixing the race completely. This can be used to implement the signal hadling in event loops, e.g. L, L, L and so on. =item Background threads want speedy reporting Assume you want very exact timing, and you can spare an extra cpu core for that. Then you can run an extra thread that signals your perl interpreter. This means you can get a very exact timing source while your perl code is number crunching, without even using a syscall to communicate between your threads. For example the deliantra game server uses a variant of this technique to interrupt background processes regularly to send map updates to game clients. Or L uses an interrupt object to wake up perl when new events have arrived. L and L could also use this to speed up result reporting. =item Speedy event loop invocation One could use this module e.g. in L to interrupt a running coro-thread and cause it to enter the event loop. Or one could bind to C and tell some important sockets to send this signal, causing the event loop to be entered to reduce network latency. =back =head2 HOW TO USE You can use this module by creating an C object for each such event source. This object stores a perl and/or a C-level callback that is invoked when the C object gets signalled. It is executed at the next time the perl interpreter is running (i.e. it will interrupt a computation, but not an XS function or a syscall). You can signal the C object either by calling it's C<< ->signal >> method, or, more commonly, by calling a C function. There is also the built-in (POSIX) signal source. The C<< ->signal_func >> returns the address of the C function that is to be called (plus an argument to be used during the call). The signalling function also takes an integer argument in the range SIG_ATOMIC_MIN to SIG_ATOMIC_MAX (guaranteed to allow at least 0..127). Since this kind of interruption is fast, but can only interrupt a I interpreter, there is optional support for signalling a pipe - that means you can also wait for the pipe to become readable (e.g. via L or L). This, of course, incurs the overhead of a C and C syscall. =head1 USAGE EXAMPLES =head2 Implementing race-free signal handling This example uses a single event pipe for all signals, and one Async::Interrupt per signal. This code is actually what the L module uses itself when Async::Interrupt is available. First, create the event pipe and hook it into the event loop $SIGPIPE = new Async::Interrupt::EventPipe; $SIGPIPE_W = AnyEvent->io ( fh => $SIGPIPE->fileno, poll => "r", cb => \&_signal_check, # defined later ); Then, for each signal to hook, create an Async::Interrupt object. The callback just sets a global variable, as we are only interested in synchronous signals (i.e. when the event loop polls), which is why the pipe draining is not done automatically. my $interrupt = new Async::Interrupt cb => sub { undef $SIGNAL_RECEIVED{$signum} }, signal => $signum, pipe => [$SIGPIPE->filenos], pipe_autodrain => 0, ; Finally, the I/O callback for the event pipe handles the signals: sub _signal_check { # drain the pipe first $SIGPIPE->drain; # two loops, just to be sure while (%SIGNAL_RECEIVED) { for (keys %SIGNAL_RECEIVED) { delete $SIGNAL_RECEIVED{$_}; warn "signal $_ received\n"; } } } =head2 Interrupt perl from another thread This example interrupts the Perl interpreter from another thread, via the XS API. This is used by e.g. the L module. On the Perl level, a new loop object (which contains the thread) is created, by first calling some XS constructor, querying the C-level callback function and feeding that as the C into the Async::Interrupt constructor: my $self = XS_thread_constructor; my ($c_func, $c_arg) = _c_func $self; # return the c callback my $asy = new Async::Interrupt c_cb => [$c_func, $c_arg]; Then the newly created Interrupt object is queried for the signaling function that the newly created thread should call, and this is in turn told to the thread object: _attach $self, $asy->signal_func; So to repeat: first the XS object is created, then it is queried for the callback that should be called when the Interrupt object gets signalled. Then the interrupt object is queried for the callback fucntion that the thread should call to signal the Interrupt object, and this callback is then attached to the thread. You have to be careful that your new thread is not signalling before the signal function was configured, for example by starting the background thread only within C<_attach>. That concludes the Perl part. The XS part consists of the actual constructor which creates a thread, which is not relevant for this example, and two functions, C<_c_func>, which returns the Perl-side callback, and C<_attach>, which configures the signalling functioon that is safe toc all from another thread. For simplicity, we will use global variables to store the functions, normally you would somehow attach them to C<$self>. The C simply returns the address of a static function and arranges for the object pointed to by C<$self> to be passed to it, as an integer: void _c_func (SV *loop) PPCODE: EXTEND (SP, 2); PUSHs (sv_2mortal (newSViv (PTR2IV (c_func)))); PUSHs (sv_2mortal (newSViv (SvRV (loop)))); This would be the callback (since it runs in a normal Perl context, it is permissible to manipulate Perl values): static void c_func (pTHX_ void *loop_, int value) { SV *loop_object = (SV *)loop_; ... } And this attaches the signalling callback: static void (*my_sig_func) (void *signal_arg, int value); static void *my_sig_arg; void _attach (SV *loop_, IV sig_func, void *sig_arg) CODE: { my_sig_func = sig_func; my_sig_arg = sig_arg; /* now run the thread */ thread_create (&u->tid, l_run, 0); } And C (the background thread) would eventually call the signaling function: my_sig_func (my_sig_arg, 0); You can have a look at L for an actual example using intra-thread communication, locking and so on. =head1 THE Async::Interrupt CLASS =over 4 =cut package Async::Interrupt; use common::sense; BEGIN { # the next line forces initialisation of internal # signal handling variables, otherwise, PL_sig_pending # etc. might be null pointers. $SIG{KILL} = sub { }; our $VERSION = 1.21; require XSLoader; XSLoader::load ("Async::Interrupt", $VERSION); } our $DIED = sub { warn "$@" }; =item $async = new Async::Interrupt key => value... Creates a new Async::Interrupt object. You may only use async notifications on this object while it exists, so you need to keep a reference to it at all times while it is used. Optional constructor arguments include (normally you would specify at least one of C or C). =over 4 =item cb => $coderef->($value) Registers a perl callback to be invoked whenever the async interrupt is signalled. Note that, since this callback can be invoked at basically any time, it must not modify any well-known global variables such as C<$/> without restoring them again before returning. The exceptions are C<$!> and C<$@>, which are saved and restored by Async::Interrupt. If the callback should throw an exception, then it will be caught, and C<$Async::Interrupt::DIED> will be called with C<$@> containing the exception. The default will simply C about the message and continue. =item c_cb => [$c_func, $c_arg] Registers a C callback the be invoked whenever the async interrupt is signalled. The C callback must have the following prototype: void c_func (pTHX_ void *c_arg, int value); Both C<$c_func> and C<$c_arg> must be specified as integers/IVs, and C<$value> is the C passed to some earlier call to either C<$signal> or the C function. Note that, because the callback can be invoked at almost any time, you have to be careful at saving and restoring global variables that Perl might use (the exception is C, which is saved and restored by Async::Interrupt). The callback itself runs as part of the perl context, so you can call any perl functions and modify any perl data structures (in which case the requirements set out for C apply as well). =item var => $scalar_ref When specified, then the given argument must be a reference to a scalar. The scalar will be set to C<0> initially. Signalling the interrupt object will set it to the passed value, handling the interrupt will reset it to C<0> again. Note that the only thing you are legally allowed to do is to is to check the variable in a boolean or integer context (e.g. comparing it with a string, or printing it, will I it and might cause your program to crash or worse). =item signal => $signame_or_value When this parameter is specified, then the Async::Interrupt will hook the given signal, that is, it will effectively call C<< ->signal (0) >> each time the given signal is caught by the process. Only one async can hook a given signal, and the signal will be restored to defaults when the Async::Interrupt object gets destroyed. =item signal_hysteresis => $boolean Sets the initial signal hysteresis state, see the C method, below. =item pipe => [$fileno_or_fh_for_reading, $fileno_or_fh_for_writing] Specifies two file descriptors (or file handles) that should be signalled whenever the async interrupt is signalled. This means a single octet will be written to it, and before the callback is being invoked, it will be read again. Due to races, it is unlikely but possible that multiple octets are written. It is required that the file handles are both in nonblocking mode. The object will keep a reference to the file handles. This can be used to ensure that async notifications will interrupt event frameworks as well. Note that C will create a suitable signal fd automatically when your program requests one, so you don't have to specify this argument when all you want is an extra file descriptor to watch. If you want to share a single event pipe between multiple Async::Interrupt objects, you can use the C class to manage those. =item pipe_autodrain => $boolean Sets the initial autodrain state, see the C method, below. =back =cut sub new { my ($class, %arg) = @_; my $self = bless \(_alloc $arg{cb}, @{$arg{c_cb}}[0,1], @{$arg{pipe}}[0,1], $arg{signal}, $arg{var}), $class; # urgs, reminds me of Event for my $attr (qw(pipe_autodrain signal_hysteresis)) { $self->$attr ($arg{$attr}) if exists $arg{$attr}; } $self } =item ($signal_func, $signal_arg) = $async->signal_func Returns the address of a function to call asynchronously. The function has the following prototype and needs to be passed the specified C<$signal_arg>, which is a C cast to C: void (*signal_func) (void *signal_arg, int value) An example call would look like: signal_func (signal_arg, 0); The function is safe to call from within signal and thread contexts, at any time. The specified C is passed to both C and Perl callback. C<$value> must be in the valid range for a C, except C<0> (1..127 is portable). If the function is called while the Async::Interrupt object is already signaled but before the callbacks are being executed, then the stored C is either the old or the new one. Due to the asynchronous nature of the code, the C can even be passed to two consecutive invocations of the callback. =item $address = $async->c_var Returns the address (cast to IV) of an C variable. The variable is set to C<0> initially and gets set to the passed value whenever the object gets signalled, and reset to C<0> once the interrupt has been handled. Note that it is often beneficial to just call C to handle any interrupts. Example: call some XS function to store the address, then show C code waiting for it. my_xs_func $async->c_var; static IV *valuep; void my_xs_func (void *addr) CODE: valuep = (IV *)addr; // code in a loop, waiting while (!*valuep) ; // do something =item $async->signal ($value=1) This signals the given async object from Perl code. Semi-obviously, this will instantly trigger the callback invocation (it does not, as the name might imply, do anything with POSIX signals). C<$value> must be in the valid range for a C, except C<0> (1..127 is portable). =item $async->handle Calls the callback if the object is pending. This method does not need to be called normally, as it will be invoked automatically. However, it can be used to force handling of outstanding interrupts while the object is blocked. One reason why one might want to do that is when you want to switch from asynchronous interruptions to synchronous one, using e.g. an event loop. To do that, one would first C<< $async->block >> the interrupt object, then register a read watcher on the C that calls C<< $async->handle >>. This disables asynchronous interruptions, but ensures that interrupts are handled by the event loop. =item $async->signal_hysteresis ($enable) Enables or disables signal hysteresis (default: disabled). If a POSIX signal is used as a signal source for the interrupt object, then enabling signal hysteresis causes Async::Interrupt to reset the signal action to C in the signal handler and restore it just before handling the interruption. When you expect a lot of signals (e.g. when using SIGIO), then enabling signal hysteresis can reduce the number of handler invocations considerably, at the cost of two extra syscalls. Note that setting the signal to C can have unintended side effects when you fork and exec other programs, as often they do not expect signals to be ignored by default. =item $async->block =item $async->unblock Sometimes you need a "critical section" of code that will not be interrupted by an Async::Interrupt. This can be implemented by calling C<< $async->block >> before the critical section, and C<< $async->unblock >> afterwards. Note that there must be exactly one call of C for every previous call to C (i.e. calls can nest). Since ensuring this in the presence of exceptions and threads is usually more difficult than you imagine, I recommend using C<< $async->scoped_block >> instead. =item $async->scope_block This call C<< $async->block >> and installs a handler that is called when the current scope is exited (via an exception, by canceling the Coro thread, by calling last/goto etc.). This is the recommended (and fastest) way to implement critical sections. =item ($block_func, $block_arg) = $async->scope_block_func Returns the address of a function that implements the C functionality. It has the following prototype and needs to be passed the specified C<$block_arg>, which is a C cast to C: void (*block_func) (void *block_arg) An example call would look like: block_func (block_arg); The function is safe to call only from within the toplevel of a perl XS function and will call C and C (in this order!). =item $async->pipe_enable =item $async->pipe_disable Enable/disable signalling the pipe when the interrupt occurs (default is enabled). Writing to a pipe is relatively expensive, so it can be disabled when you know you are not waiting for it (for example, with L you could disable the pipe in a check watcher, and enable it in a prepare watcher). Note that currently, while C is in effect, no attempt to read from the pipe will be done when handling events. This might change as soon as I realize why this is a mistake. =item $fileno = $async->pipe_fileno Returns the reading side of the signalling pipe. If no signalling pipe is currently attached to the object, it will dynamically create one. Note that the only valid operation on this file descriptor is to wait until it is readable. The fd might belong currently to a pipe, a tcp socket, or an eventfd, depending on the platform, and is guaranteed to be C