FBB::Selector objects are wrappers around the select()(2) system
calls and allow timed delays, alarm functionality and/or multiple file I/O. It
requires the use of file descriptors, which are not an official part of
C++. However, most operating systems offer file descriptors. Sockets
are well-known file descriptors.
NAMESPACE
FBB
All constructors, members, operators and manipulators, mentioned in this
man-page, are defined in the namespace FBB.
INHERITS FROM
-
CONSTRUCTORS
Selector():
This constructor initializes the object.
The copy constructor is available.
MEMBER FUNCTIONS
void addExceptFd(int fd):
Adds a filedescriptor to the set of file descriptors that are
monitored for exceptions (note these are not C++ exceptions. See man 2
select for details).
void addReadFd(int fd):
Adds a filedescriptor to the set of file descriptors that are
monitored for reading.
void addWriteFd(int fd):
Adds a filedescriptor to the set of file descriptors that are
monitored for writing.
int exceptFd():
Returns -1 of no more file descriptors are
available in the exception category. Otherwise the next available file
descriptor in the exception category is returned. Returning from
wait(), this function can be called repeatedly until -1 is returned,
servicing each available filedescriptor in turn.
void noAlarm():
This member prevents any timeout-alarm from occurring.
int nReady():
Returns the number of available file descriptors. 0 is returned at a
timeout, -1: is returned when select(2) itself failed.
int readFd():
Returns -1 of no more file descriptors are available for
reading. Otherwise the next available file descriptor for reading is
returned. Returning from wait(), this function can be called repeatedly
until -1 is returned, servicing each available filedescriptor in turn.
void rmExceptFd(int fd):
Removes a filedescriptor from the set of file descriptors that are
monitored for exceptions (note these are not C++ exceptions. See man 2
select for details).
void rmReadFd(int fd):
Removes a filedescriptor from the set of file descriptors that are
monitored for reading.
void rmWriteFd(int fd):
Removes a filedescriptor from the set of file descriptors that are
monitored for writing.
void setAlarm(int sec, int usec = 0):
This member sets the alarm at the indicated seconds and
milli-seconds. If no action occurred on one of the monitored file
descriptions, wait() will return with nREady() returning 0.
int wait():
This member should be called to wait for activities on the installed
file descriptors or timeout-period. The members nReady() and get...()
show their defined behaviors only after wait() has returned. It throws an
FBB::Errno exception when select() fails, which may very well indicate
the end of any available input.
int writeFd():
Returns -1 of no more file descriptors are available for
writing. Otherwise the next available file descriptor for writing is
returned. Returning from wait(), this function can be called repeatedly
until -1 is returned, servicing each available filedescriptor in turn.
EXAMPLE
#include <string>
#include <iostream>
#include <bobcat/selector>
#include <bobcat/errno>
using namespace std;
using namespace FBB;
int main(int argc, char **argv, char **envp)
{
Selector selector;
selector.setAlarm(5); // every 5 secs: alarm fires
selector.addReadFd(STDIN_FILENO); // look also at cin
try
{
while (true)
{
if (!selector.wait()) // 0: alarm fires
cout << "Are you still there?" << endl;
else
{
string s;
if (!getline(cin, s) || !s.length())
return 0;
cout << "Thank you for: " << s << endl;
}
}
}
catch (Errno const &e)
{
cout << e.what() << endl;
}
return 0;
}
FILES
bobcat/selector - defines the class interface
SEE ALSO
bobcat(7), select(2)
BUGS
None Reported.
DISTRIBUTION FILES
bobcat_2.02.03-x.dsc: detached signature;
bobcat_2.02.03-x.tar.gz: source archive;
bobcat_2.02.03-x_i386.changes: change log;
libbobcat1_2.02.03-x_*.deb: debian package holding the
libraries;
libbobcat1-dev_2.02.03-x_*.deb: debian package holding the
libraries, headers and manual pages;
http://sourceforge.net/projects/bobcat: public archive location;
BOBCAT
Bobcat is an acronym of `Brokken's Own Base Classes And Templates'.
COPYRIGHT
This is free software, distributed under the terms of the
GNU General Public License (GPL).