src/thttpd-2.27/fdwatch.h

   1 /* fdwatch.h - header file for fdwatch package
   2 **
   3 ** This package abstracts the use of the select()/poll()/kqueue()
   4 ** system calls.  The basic function of these calls is to watch a set
   5 ** of file descriptors for activity.  select() originated in the BSD world,
   6 ** while poll() came from SysV land, and their interfaces are somewhat
   7 ** different.  fdwatch lets you write your code to a single interface,
   8 ** with the portability differences hidden inside the package.
   9 **
  10 ** Usage is fairly simple.  Call fdwatch_get_nfiles() to initialize
  11 ** the package and find out how many fine descriptors are available.
  12 ** Then each time through your main loop, call fdwatch_clear(), then
  13 ** fdwatch_add_fd() for each of the descriptors you want to watch,
  14 ** then call fdwatch() to actually perform the watch.  After it returns
  15 ** you can check which descriptors are ready via fdwatch_check_fd().
  16 **
  17 ** If your descriptor set hasn't changed from the last time through
  18 ** the loop, you can skip calling fdwatch_clear() and fdwatch_add_fd()
  19 ** to save a little CPU time.
  20 **
  21 **
  22 ** Copyright © 1999 by Jef Poskanzer <jef@mail.acme.com>.
  23 ** All rights reserved.
  24 **
  25 ** Redistribution and use in source and binary forms, with or without
  26 ** modification, are permitted provided that the following conditions
  27 ** are met:
  28 ** 1. Redistributions of source code must retain the above copyright
  29 **    notice, this list of conditions and the following disclaimer.
  30 ** 2. Redistributions in binary form must reproduce the above copyright
  31 **    notice, this list of conditions and the following disclaimer in the
  32 **    documentation and/or other materials provided with the distribution.
  33 **
  34 ** THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  35 ** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  36 ** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  37 ** ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  38 ** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  39 ** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  40 ** OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  41 ** HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  42 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  43 ** OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  44 ** SUCH DAMAGE.
  45 */
  46
  47 #ifndef _FDWATCH_H_
  48 #define _FDWATCH_H_
  49
  50 #define FDW_READ 0
  51 #define FDW_WRITE 1
  52
  53 #ifndef INFTIM
  54 #define INFTIM -1
  55 #endif /* INFTIM */
  56
  57 /* Figure out how many file descriptors the system allows, and
  58 ** initialize the fdwatch data structures.  Returns -1 on failure.
  59 */
  60 int fdwatch_get_nfiles( void );
  61
  62 /* Add a descriptor to the watch list.  rw is either FDW_READ or FDW_WRITE.  */
  63 void fdwatch_add_fd( int fd, void* client_data, int rw );
  64
  65 /* Delete a descriptor from the watch list. */
  66 void fdwatch_del_fd( int fd );
  67
  68 /* Do the watch.  Return value is the number of descriptors that are ready,
  69 ** or 0 if the timeout expired, or -1 on errors.  A timeout of INFTIM means
  70 ** wait indefinitely.
  71 */
  72 int fdwatch( long timeout_msecs );
  73
  74 /* Check if a descriptor was ready. */
  75 int fdwatch_check_fd( int fd );
  76
  77 /* Get the client data for the next returned event.  Returns -1 when there
  78 ** are no more events.
  79 */
  80 void* fdwatch_get_next_client_data( void );
  81
  82 /* Generate debugging statistics syslog message. */
  83 void fdwatch_logstats( long secs );
  84
  85 #endif /* _FDWATCH_H_ */