libsecurity_utilities/lib/selector.h

   1 /*
   2  * Copyright (c) 2000-2004 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24
  25 //
  26 // selector - I/O stream multiplexing
  27 //
  28 #ifndef _H_SELECTOR
  29 #define _H_SELECTOR
  30
  31 #include <security_utilities/utilities.h>
  32 #include <security_utilities/fdsel.h>
  33 #include "timeflow.h"
  34 #include <sys/types.h>
  35 #include <cstdio>
  36 #include <cstdarg>
  37 #include <map>
  38 #include <security_utilities/debugging.h>
  39
  40
  41 namespace Security {
  42 namespace UnixPlusPlus {
  43
  44
  45 //
  46 // A Selector is an I/O dispatch facility that can supervise any number of "file descriptors",
  47 // each of which can perform I/O. Obviously this is geared towards the UNIX facility.
  48 //
  49 class Selector {
  50 public:
  51     class Client; friend class Client;
  52
  53     Selector();
  54     virtual ~Selector();
  55
  56     //@@@ preliminary interface
  57     void operator () ();                // run just once (now)
  58     void operator () (Time::Absolute stopTime);
  59     void operator () (Time::Interval duration)
  60     { (*this)(Time::now() + duration); }
  61
  62     typedef unsigned int Type;
  63     static const Type none = 0x00;
  64     static const Type input = 0x01;
  65     static const Type output = 0x02;
  66     static const Type critical = 0x04;
  67     static const Type all = input | output | critical;
  68
  69 public:
  70     class Client {
  71     public:
  72         typedef Selector::Type Type;
  73         friend class Selector;
  74
  75         Client() : mSelector(NULL) { }
  76         virtual void notify(int fd, Type type) = 0;
  77         virtual ~Client() { }
  78
  79         bool isActive() const           { return mSelector != NULL; }
  80
  81         static const Type input = Selector::input;
  82         static const Type output = Selector::output;
  83         static const Type critical = Selector::critical;
  84
  85     protected:
  86         void events(Type type)  { mSelector->set(mFd, type); mEvents = type; }
  87         Type events() const             { return mEvents; }
  88
  89         void enable(Type type)  { events(events() | type); }
  90         void disable(Type type) { events(events() & ~type); }
  91
  92         template <class Sel> Sel &selectorAs()
  93         { assert(mSelector); return safer_cast<Sel &>(*mSelector); }
  94
  95     private:
  96         int mFd;
  97         Selector *mSelector;
  98         Type mEvents;
  99     };
 100
 101     void add(int fd, Client &client, Type type = all);
 102     void remove(int fd);
 103     bool isEmpty() const                                { return clientMap.empty(); }
 104
 105 private:
 106     void set(int fd, Type type);                // (re)set mask for one client
 107
 108     void singleStep(Time::Interval maxWait);
 109
 110 private:
 111     unsigned int fdSetSize;                             // number of fd_masks allocated in FDSets
 112     int fdMin, fdMax;                                   // highest/lowest fds in use
 113     FDSet inSet, outSet, errSet;                // current in/out/error select masks
 114
 115 private:
 116     typedef map<int, Client *> ClientMap;
 117     ClientMap clientMap;
 118 };
 119
 120
 121 }       // end namespace UnixPlusPlus
 122 }       // end namespace Security
 123
 124
 125 #endif //_H_SELECTOR