/* * The Unix Channel * * by Michel Beaudouin-Lafon * * Copyright 1990-1993 * Laboratoire de Recherche en Informatique (LRI) * * Channel sets, or multiplexers * * $Id$ * $CurLog$ */ #include "Multiplexer.h" #include "TimeOut.h" #include "SignalHandler.h" #include // for NSIG #include #include #include #include #include #include #include #if defined(__hpux) && !defined(__GNUG__) #define FD_SET_TYPE(x) ((int*) x) #else #define FD_SET_TYPE(x) (x) #endif #ifdef __osf__ extern "C" int select (int, fd_set*, fd_set*, fd_set*, struct timeval*); #endif extern int errno; #ifndef FD_SET #ifndef NFDBITS #define FD_SET(n, p) ((p)->fds_bits[0] |= (1 << (n))) #define FD_CLR(n, p) ((p)->fds_bits[0] &= ~(1 << (n))) #define FD_ISSET(n, p) ((p)->fds_bits[0] & (1 << (n))) #define FD_ZERO(p) ((p)->fds_bits[0] = 0) #else #define FD_SET(n, p) ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS))) #define FD_CLR(n, p) ((p)->fds_bits[(n)/NFDBITS] &= ~(1 << ((n) % NFDBITS))) #define FD_ISSET(n, p) ((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS))) #define FD_ZERO(p) memset((char *)(p), 0, sizeof(*(p))) #endif #endif /*?class UchBaseMultiplexer Multiplexers make it possible to handle several communication channels at the same time; their implementation is based on the Unix \com{select} system call or similar mechanisms. Multiplexers are also able to implement safe (ie. not interruption-based) timers and signal handlers. Some of the channels in the set are active, others can be inactive. A multiplexer can be scanned so that the functions \fun{HandleRead} and \fun{HandleWrite} are called for every active channel that is ready to read or write. The functions \fun{HandleSelect} of each channel is called before actually scanning so that each channel can perform a background task or buffer input/output. Multiplexers may have different implementations, depending on the environment. When no other library is involved, they are simply implemented on top of Unix. But if \uch\ channels have to be mixed with the X Toolkit for instance, the implementation uses the mechanisms provided by the X Toolkit to add new channels. The same holds for Tcl/Tk or other environments. Every such implentation corresponds to a derived class of \typ{UchBaseMultiplexer}, which offers a uniform interface that hides the implementation differences. See the class \typ{UchMultiplexer} for a ``pure \uch'' implementation of multiplexers. Note that the functions that take an integer file descriptor as argument can be passed a \typ{FILDES} or a \typ{UchChannel} because the corresponding conversion operators are defined. ?*/ /*? Create an empty channel set. ?*/ UchBaseMultiplexer :: UchBaseMultiplexer () : Channels (new pUchChannel [NFILE]), Timers (), ReadCount (0), WriteCount (0), SelectCount (0), Looping (false), SigFired (false), Handlers (new UchBaseSignalHandler* [NSIG]), NbSignals (new int [NSIG]) { memset (Handlers, 0, NSIG * sizeof (UchBaseSignalHandler*)); memset (NbSignals, 0, NSIG * sizeof (int)); } /*?nodoc?*/ UchBaseMultiplexer :: ~UchBaseMultiplexer () { #ifdef CPLUS_BUG4 delete [NFILE] Channels; #else delete [] Channels; delete [] NbSignals; delete [] Handlers; #endif Channels = 0; } /*? Add a channel to the set. Note that the argument is a pointer to the channel; no copy is made by this function. If a channel with the same file descriptor as the one being added is already in the set, the old channel is first removed. ?*/ void UchBaseMultiplexer :: Add (UchChannel* chan) { int fd = chan->FilDes (); if (fd < 0) return; pUchChannel ochan = Channels [fd]; if (ochan) Remove (fd); chan->Added (*this); Channels [fd] = chan; SetMasks (fd, chan->IOMode ()); } pUchChannel NIL_CHAN (0); /*? Remove a channel from the set. This function can be passed a \var{UchChannel}. ?*/ void UchBaseMultiplexer :: Remove (int fd) { if (fd < 0) return; UchChannel* ch = Channels [fd]; if (ch) { ch->Removed (*this); SetMasks (fd, IONone); Channels [fd] = 0; } } /*? Remove all channels from this channel set. This function calls \fun{Remove} for all channels of the set. This is a way of exiting from \fun{LoopScan}. ?*/ void UchBaseMultiplexer :: RemoveAll () { for (int fd = 0; fd < NFILE; fd++) Remove (fd); } /*? Change the mode of a channel in the set. Mode \var{IONone} makes the channel inactive (without removing it). This function can be passed a \var{UchChannel}. ?*/ void UchBaseMultiplexer :: SetMode (int fd, IOMODE mode) { if (fd < 0) return; SetMasks (fd, mode); Channels [fd] -> SetMode (mode); } #ifdef DOC /*? This array operator returns a (smart) pointer to the channel corresponding to file descriptor \var{fd}. If there is no such channel in this channel set, the operator returns NIL. ?*/ pUchChannel UchBaseMultiplexer :: operator [] (int fd) { } /*? Add a channel to the set. Here the argument is a reference, and a dynamically allocated copy of it is actually added. Compare with previous function. ?*/ void UchBaseMultiplexer :: Add (const UchChannel& ch) { } #endif /* DOC */ /*! This function is called by UchSignalHandlers when a signal is received. It just stores the signal for future (and safe) handling. !*/ /*?hidden?*/ void UchBaseMultiplexer :: HandleSignal (UchBaseSignalHandler& h) { if (!SigFired) AddSignalHook (); SigFired = true; int sig = h.GetSignal () - 1; /* We have to work with arrays, because we are in a signal handler, and we cannot use lists */ Handlers [sig] = &h; NbSignals [sig]++; } /*! This virtual function is called the first time when a signal is received by a signal handler associated to the multiplexer. It makes it possible to call implementation-dependant functions that defer the handling to safer times. !*/ /* Does not need to be defined in UchMultiplexer, because they use the flag SigFired. */ /*?hidden?*/ void UchBaseMultiplexer :: AddSignalHook () { } /*! This function triggers the handling of all deferred signals. It should be called when \fun{AddSignalHook} has been called and the times are safe. !*/ /*?hidden?*/ void UchBaseMultiplexer :: HandleDeferredSignals () { CcuSignalBlocker b (AllSigs); int c; for (int i = 0; i < NSIG; ++i) if (c = NbSignals [i]) { Handlers [i]->DeferredHandle (c); NbSignals [i] = 0; Handlers [i] = 0; } } /*?hidden?*/ void UchBaseMultiplexer :: SetMasks (int, IOMODE) { } static jmp_buf reset_run; class UchMpxAborter : public UchBaseSignalHandler { public: UchMpxAborter (UchBaseMultiplexer& m, int s) : UchBaseSignalHandler (m, s) {} void DeferredHandle (int) { MyMpx.Abort (); } }; /*? Run a multiplexer: make it repeatedly scan its channels, and take the appropriate actions. This function will exit under a number of circumstances, reflected by its return value. \small \begin{tabular}{ll} \var{isMpxTerminated}&the method \fun{Close} has been called.\\ \var{isMpxEmpty}&there are no more channels in the set.\\ \var{isMpxAborted}&the method \fun{Abort} has been called, or signals SIGINT or SIGTERM were received.\\ \var{isMpxError}&an error has occured. \end{tabular} ?*/ MPX_RES UchBaseMultiplexer :: Run () { if (setjmp (reset_run)) return isMpxAborted; UchMpxAborter h1 (*this, SigTerm); UchMpxAborter h2 (*this, SigInt); return Loop (); } /*? Remove all channels from the multiplexer, thus stopping it if running. ?*/ void UchBaseMultiplexer :: Close () { RemoveAll (); Looping = false; } /*? Stop the multiplexer, without cleaning it. ?*/ void UchBaseMultiplexer :: Abort () { if (Looping) longjmp (reset_run, 1); } /*?class UchMultiplexer The class \typ{UchMultiplexer} is the default implementation of multiplexers, used when there are no compatibility needs. For historical reasons, it offers a number of additional methods. ?*/ /*? Build an empty multiplexer. ?*/ UchMultiplexer :: UchMultiplexer () : UchBaseMultiplexer (), TimeOut (-1) { FD_ZERO (&ReadMask); FD_ZERO (&WriteMask); FD_ZERO (&SelectMask); } /*?nodoc?*/ UchMultiplexer :: ~UchMultiplexer () { } // update the masks when channel fd changes its mode // /*?hidden?*/ void UchMultiplexer :: SetMasks (int fd, IOMODE mode) { if (mode & IORead) { if (! FD_ISSET (fd, &ReadMask)) { ReadCount ++; FD_SET (fd, &ReadMask); } } else { if (FD_ISSET (fd, &ReadMask)) { FD_CLR (fd, &ReadMask); ReadCount --; } } if (mode & IOWrite) { if (! FD_ISSET (fd, &WriteMask)) { WriteCount ++; FD_SET (fd, &WriteMask); } } else { if (FD_ISSET (fd, &WriteMask)) { FD_CLR (fd, &WriteMask); WriteCount --; } } if (mode & IOSelect) { if (! FD_ISSET (fd, &SelectMask)) { SelectCount ++; FD_SET (fd, &SelectMask); } } else { if (FD_ISSET (fd, &SelectMask)) { FD_CLR (fd, &SelectMask); SelectCount --; } } } /*? This function calls the select handler of each channel of the set in select mode. It returns true as soon as one select handler returns true, else it returns false when the select handlers have been called. ?*/ bool UchMultiplexer :: HandleSelect () { int fd, nfd; if (fd0 >= NFILE) fd0 = 0; for (fd = fd0++, nfd = SelectCount; nfd; (fd < NFILE) ? fd++ : (fd = 0)) { if (! FD_ISSET (fd, &SelectMask)) continue; if (Channels [fd] -> HandleSelect ()) return true; nfd--; if (! Looping) return false; } return false; } ////// should add signal handling /*?nextdoc?*/ int UchMultiplexer :: Scan (bool nointr, bool poll) { fd_set rmsk, wmsk; int nfd, ret = -1; register int fd; struct timeval tout; struct timeval* timeout = 0; if (poll) { timeout = &tout; tout.tv_sec = tout.tv_usec = 0; } while (ret <= 0) { CcuCoreTimer::Fire (&Timers); if (ReadCount == 0 && WriteCount == 0 && SelectCount == 0) return 0; for (fd = 0, nfd = SelectCount; nfd; fd++) { if (! FD_ISSET (fd, &SelectMask)) continue; UchChannel* ch = Channels [fd]; if (ch && ch->HandleSelect ()) return -2; nfd--; } //printf ("Scan: read %x, write %x, TimeOut %d", ReadMask, WriteMask, TimeOut); rmsk = ReadMask; wmsk = WriteMask; if (!poll && TimeOut != -1) { CcuTimeStamp now; Millisecond delay = TimeOut - now; //printf (", timeout in %d ms", delay); tout.tv_sec = delay / 1000; tout.tv_usec = 1000 * (delay % 1000); timeout = &tout; } //printf ("\n"); ret = select (NFILE, FD_SET_TYPE(&rmsk) /*read*/, FD_SET_TYPE(&wmsk) /*write*/, 0 /*except*/, timeout); if (ret < 0 || ret == 0 && poll) { //printf ("select failed: %d, errno %d\n", ret, errno); if (nointr && ret == -1 && errno == EINTR) continue; return ret; } } for (fd = 0, nfd = ret; nfd; fd++) { //printf ("Scan: handle %d: r %d, w %d\n", fd, FD_ISSET (fd, &rmsk), FD_ISSET (fd, &wmsk)); if (FD_ISSET (fd, &wmsk)) { nfd --; UchChannel* ch = Channels [fd]; if (ch) ch->HandleWrite (); } if (FD_ISSET (fd, &rmsk)) { nfd--; UchChannel* ch = Channels [fd]; if (ch) ch->HandleRead (); } } return ret; } /*? Scan the channels in the set and call the channel's handlers. First the select handler (\fun{UchChannel::HandleSelect}) of each channel with mode \var{IOSelect} is called. If it returns true, \fun{Scan} exits immediately, while \fun{LoopScan} loops immediately. If no select handler returns true, the system call \fun{select} is used to poll or wait for the channels that are ready. When the select returns normally, the write handlers \fun{HandleWrite} of the channels in mode \var{IOWrite} that are ready to write are called, and the read handlers (\fun{HandleRead}) of the channels in mode \fun{IORead} that are ready to read are called. If \var{nointr} is true, ignore the interrupted system calls, else return an error whenever the \fun{select} system call is interrupted. If \var{poll} is true, the call is non-blocking, else it is blocking. \fun{Scan} calls \fun{select} only once; it returns -2 if a select handler returns, it returns 0 if the channel set has no active channels, else it returns the return code of \fun{select}. \fun{LoopScan} calls \fun{select} repeatedly until \var{LoopEnd} is called, or an error occurs, the channel set has no more active channel This can occur because the select, read or write handler of a channel may remove the channel or change its mode. This is usually done when the read handler detects an end of file. \fun{LoopScan} returns \var{isMpxEmpty} when there are no more active channel in the set, it returns \var{isMpxError} when an error occured (the code is in \var{errno}), and it returns \var{isMpxTerminated} if \fun{LoopEnd} or \fun{Close} was called. ?*/ MPX_RES UchMultiplexer :: LoopScan (bool nointr) { fd_set rmsk, wmsk; register int nfd, fd; Looping = true; for (fd0 = 0; Looping; fd0 < NFILE ? fd0++ : (fd0 = 0)) { /* First, handle signals */ if (SigFired) HandleDeferredSignals (); /* Then, timers */ CcuCoreTimer::Fire (&Timers); /* Then, I/Os */ if (ReadCount == 0 && WriteCount == 0 && SelectCount == 0) return isMpxEmpty; for (fd = fd0, nfd = SelectCount; nfd; (fd < NFILE) ? fd++ : (fd = 0)) { if (! FD_ISSET (fd, &SelectMask)) continue; UchChannel* ch = Channels [fd]; if (ch && ch->HandleSelect ()) break; nfd--; if (! Looping) return isMpxTerminated; } if (nfd) // a handler returned true. continue; rmsk = ReadMask; wmsk = WriteMask; struct timeval tv; struct timeval* timeout = 0; if (TimeOut != -1) { CcuTimeStamp now; Millisecond delay = TimeOut - now; tv.tv_sec = delay / 1000; tv.tv_usec = 1000 * (delay % 1000); timeout = &tv; } nfd = select (NFILE, FD_SET_TYPE(&rmsk) /*read*/, FD_SET_TYPE(&wmsk) /*write*/, 0 /*except*/, timeout); if (nfd < 0) { if (nointr && nfd == -1 && errno == EINTR) continue; return isMpxError; } for (fd = fd0; nfd; (fd < NFILE) ? fd++ : (fd = 0)) { if (FD_ISSET (fd, &wmsk)) { nfd--; Channels [fd] -> HandleWrite (); if (! Looping) return isMpxTerminated; } if (FD_ISSET (fd, &rmsk)) { nfd--; Channels [fd] -> HandleRead (); if (! Looping) return isMpxTerminated; } } } return isMpxTerminated; } /*?nodoc?*/ char* UchMultiplexer :: StrRepr (char* buf) { sprintf (buf, "R:%ux W:%ux", ReadMask, WriteMask); return buf; } #ifdef DOC // fake entries for inline functions /*? This function makes \fun{LoopScan} exit immediately. Thus it must be called from within a channel's handler. ?*/ void UchMultiplexer :: LoopEnd () { } #endif /* DOC */ /*?hidden?*/ void UchMultiplexer :: SetTimeOut (Millisecond delay) { CcuTimeStamp now; TimeOut = now + delay; } /*?hidden?*/ void UchMultiplexer :: SuppressTimeOut () { TimeOut = -1; } /*?hidden?*/ MPX_RES UchMultiplexer :: Loop () { return LoopScan (); }