\d dZddlZddlZddlZddlZddlZddlmZmZm Z ddl m Z m Z m Z ddlmZedkrddlmZmZd Zd ZGd d eZe eGd de jZGdde jZe eGddeZedkreZneZGddeZdS)a9 This module is used to integrate child process termination into a reactor event loop. This is a challenging feature to provide because most platforms indicate process termination via SIGCHLD and do not provide a way to wait for that signal and arbitrary I/O events at the same time. The naive implementation involves installing a Python SIGCHLD handler; unfortunately this leads to other syscalls being interrupted (whenever SIGCHLD is received) and failing with EINTR (which almost no one is prepared to handle). This interruption can be disabled via siginterrupt(2) (or one of the equivalent mechanisms); however, if the SIGCHLD is delivered by the platform to a non-main thread (not a common occurrence, but difficult to prove impossible), the main thread (waiting on select() or another event notification API) may not wake up leading to an arbitrary delay before the child termination is noticed. The basic solution to all these issues involves enabling SA_RESTART (ie, disabling system call interruption) and registering a C signal handler which writes a byte to a pipe. The other end of the pipe is registered with the event loop, allowing it to wake up shortly after SIGCHLD is received. See L{twisted.internet.posixbase._SIGCHLDWaker} for the implementation of the event loop side of this solution. The use of a pipe this way is known as the U{self-pipe trick}. From Python version 2.6, C{signal.siginterrupt} and C{signal.set_wakeup_fd} provide the necessary C signal handler which writes to the pipe to be registered with C{SA_RESTART}. N) Attribute Interface implementer)failurelogutil) platformTypeposix)fdescprocessc |dkr*tjtjtjnAd}tjtj|tjtjdtj|S)a Install a signal handler which will write a byte to C{fd} when I{SIGCHLD} is received. This is implemented by installing a SIGCHLD handler that does nothing, setting the I{SIGCHLD} handler as not allowed to interrupt system calls, and using L{signal.set_wakeup_fd} to do the actual writing. @param fd: The file descriptor to which to write when I{SIGCHLD} is received. @type fd: C{int} cdSN)argss 9lib/python3.11/site-packages/twisted/internet/_signals.pynoopSignalHandlerz)installHandler..noopSignalHandlerDs DF)signalSIGCHLDSIG_DFL siginterrupt set_wakeup_fd)fdrs rinstallHandlerr3sr Rxx fnfn5555     fn&7888FNE222   # ##rcZtjtjtjkS)zI Determine whether the I{SIGCHLD} handler is the default or not. )r getsignalrrrrrisDefaultHandlerr Ls  FN + +v~ ==rcNeZdZdZedZdZdZdej ddfdZ dS) _IWakeraQ Interface to wake up the event loop based on the self-pipe trick. The U{I{self-pipe trick}}, used to wake up the main loop from another thread or a signal handler. This is why we have wakeUp together with doRead This is used by threads or signals to wake up the event loop. cdS)z: Called when the event should be wake up. NrrrrwakeUpz_IWaker.wakeUp`rcdS)zC Read some data from my connection and discard it. NrrrrdoReadz_IWaker.doReader&rreasonreturnNcdS)zB Called when connection was closed and the pipes. Nr)r)s rconnectionLostz_IWaker.connectionLostjr&r) __name__ __module__ __qualname____doc__r disconnectedr%r(rFailurer,rrrr"r"Sso9R==L       w 4      rr"c.eZdZdZdZdZdZdZdZdS) _SocketWakerz The I{self-pipe trick}, implemented using a pair of sockets rather than pipes (due to the lack of support in select() on Windows for pipes), used to wake up the main loop from another thread. rc||_tjtjtj}|tjtjdtjtjtjtj5}| d| d| | | \}}dddn #1swxYwY|d|d||_||_|jj|_dS) Initialize.r )z 127.0.0.1rNr)reactorsocketAF_INET SOCK_STREAM setsockopt IPPROTO_TCP TCP_NODELAY contextlibclosingbindlistenconnect getsocknameaccept setblockingrwfileno)selfr7clientserverreader clientaddrs r__init__z_SocketWaker.__init__{sS v~v/ABB&,f.@!DDD   M&.&*< = =   1  KK( ) ) ) MM!    NN6--// 0 0 0!' FJ  1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11fm sA)D  DDc tj|jjddS#t$r'}|jdt jkrYd}~dSd}~wwxYw)zSend a byte to my connection.xrN)runtilConcludesrGsendOSErrorrerrnoWSAEWOULDBLOCKrIes rr%z_SocketWaker.wakeUpsn    T 2 2 2 2 2   vayE000100000 s# AAAc^ |jddS#t$rYdSwxYw)z4 Read some data from my connection. i N)rFrecvrSrIs rr(z_SocketWaker.doReadsC  FKK         DD s  ,,cj|j|jdSr)rFcloserG)rIr)s rr,z_SocketWaker.connectionLosts$    rN) r-r.r/r0r1rNr%r(r,rrrr4r4psaL$$$&rr4c0eZdZdZdZdZdZdZdZdZ dS)_FDWakera The I{self-pipe trick}, used to wake up the main loop from another thread or a signal handler. L{_FDWaker} is a base class for waker implementations based on writing to a pipe being monitored by the reactor. @ivar o: The file descriptor for the end of the pipe which can be written to wake up a reactor monitoring this waker. @ivar i: The file descriptor which should be monitored in order to be awoken by this waker. rNc2|_tj\__t jjt jjt jjt jjfd_dS)r6cjSr)irZsrz#_FDWaker.__init__..s dfrN) r7ospiperaor setNonBlocking_setCloseOnExecrHrIr7s` rrNz_FDWaker.__init__sz  TV$$$ df%%% TV$$$ df%%%$nnn rcVtj|ddS)zA Read some bytes from the pipe and discard them. cdSrr)datas rrbz!_FDWaker.doRead..sTrN)r readFromFDrHrZs rr(z_FDWaker.doReads) (9(9:::::rct|dsdS|j|jfD]'} tj|#t $rY$wxYw|`|`dS)zClose both ends of my pipe.reN)hasattrrarercr\rS)rIr)rs rr,z_FDWaker.connectionLostsqtS!!  F&$&.  B       FDFFFs9 AA) r-r.r/r0r1rarerNr(r,rrrr^r^s\  L A A%%%;;;     rr^ceZdZdZdZdS) _UnixWakerz This class provides a simple interface to wake up the event loop. This is used by threads or signals to wake up the event loop. c|jV tjtj|jddS#t $r!}|jt jkrYd}~dSd}~wwxYwdS)z)Write one byte to the pipe, and flush it.NrP)rerrQrcwriterSrTEAGAINrVs rr%z_UnixWaker.wakeUps 6  #BHdfd;;;;;   7el**+*****   s%0 AAAN)r-r.r/r0r%rrrrprps-     rrpc*eZdZdZdZdZdZdZdS) _SIGCHLDWakerzU L{_SIGCHLDWaker} can wake up a reactor whenever C{SIGCHLD} is received. c<t||dSr)r^rNrhs rrNz_SIGCHLDWaker.__init__s$(((((rc.t|jdS)zJ Install the handler necessary to make this waker active. N)rrerZs rinstallz_SIGCHLDWaker.installs tvrc$tddS)zC Remove the handler which makes this waker active. rN)rrZs r uninstallz_SIGCHLDWaker.uninstalls rrc`t|tjdS)a Having woken up the reactor in response to receipt of C{SIGCHLD}, reap the process which exited. This is called whenever the reactor notices the waker pipe is writeable, which happens soon after any call to the C{wakeUp} method. N)r^r(r reapAllProcessesrZs rr(z_SIGCHLDWaker.doReads+  """""rN)r-r.r/r0rNrxrzr(rrrrurusZ )))  # # # # #rru)r0r>rTrcrr8zope.interfacerrrtwisted.pythonrrrtwisted.python.runtimer r#r r rr r"Loggerr4r^rp_Wakerrurrrrs > <<<<<<<<<<----------//////7        $$$2>>>     i   : W000003:000f-----sz---` W*7 FFF#####H#####r