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selector.h

/*
 * Copyright (c) 2000-2004 Apple Computer, Inc. All Rights Reserved.
 * 
 * @APPLE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */


//
// selector - I/O stream multiplexing
//
#ifndef _H_SELECTOR
#define _H_SELECTOR

#include <security_utilities/utilities.h>
#include <security_utilities/fdsel.h>
#include "timeflow.h"
#include <sys/types.h>
#include <cstdio>
#include <cstdarg>
#include <map>
#include <security_utilities/debugging.h>


namespace Security {
namespace UnixPlusPlus {


//
// A Selector is an I/O dispatch facility that can supervise any number of "file descriptors",
// each of which can perform I/O. Obviously this is geared towards the UNIX facility.
//
class Selector {
public:
    class Client; friend class Client;

    Selector();
    virtual ~Selector();
    
    //@@@ preliminary interface
    void operator () ();            // run just once (now)
    void operator () (Time::Absolute stopTime);
    void operator () (Time::Interval duration)
    { (*this)(Time::now() + duration); }
    
    typedef unsigned int Type;
    static const Type none = 0x00;
    static const Type input = 0x01;
    static const Type output = 0x02;
    static const Type critical = 0x04;
    static const Type all = input | output | critical;
    
public:
    class Client {
    public:
        typedef Selector::Type Type;
        friend class Selector;

        Client() : mSelector(NULL) { }
        virtual void notify(int fd, Type type) = 0;
        virtual ~Client() { }
        
        bool isActive() const       { return mSelector != NULL; }

        static const Type input = Selector::input;
        static const Type output = Selector::output;
        static const Type critical = Selector::critical;
        
    protected:
        void events(Type type)      { mSelector->set(mFd, type); mEvents = type; }
        Type events() const         { return mEvents; }

        void enable(Type type)      { events(events() | type); }
        void disable(Type type)     { events(events() & ~type); }

        template <class Sel> Sel &selectorAs()
        { assert(mSelector); return safer_cast<Sel &>(*mSelector); }
        
    private:
        int mFd;
        Selector *mSelector;
        Type mEvents;
    };
    
    void add(int fd, Client &client, Type type = all);
    void remove(int fd);
    bool isEmpty() const                        { return clientMap.empty(); }
    
private:
    void set(int fd, Type type);          // (re)set mask for one client
    
    void singleStep(Time::Interval maxWait);
    
private:
    unsigned int fdSetSize;                     // number of fd_masks allocated in FDSets
    int fdMin, fdMax;                           // highest/lowest fds in use
    FDSet inSet, outSet, errSet;          // current in/out/error select masks
    
private:
    typedef map<int, Client *> ClientMap;
    ClientMap clientMap;
};


}     // end namespace UnixPlusPlus
}     // end namespace Security


#endif //_H_SELECTOR

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