UsageEnvironment/include/UsageEnvironment.hh

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/**********
This library is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the
Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version. (See <http://www.gnu.org/copyleft/lesser.html>.)

This library is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for
more details.

You should have received a copy of the GNU Lesser General Public License
along with this library; if not, write to the Free Software Foundation, Inc.,
59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
**********/
// Copyright (c) 1996-2008 Live Networks, Inc.  All rights reserved.
// Usage Environment
// C++ header

#ifndef _USAGE_ENVIRONMENT_HH
#define _USAGE_ENVIRONMENT_HH

#ifndef _USAGEENVIRONMENT_VERSION_HH
#include "UsageEnvironment_version.hh"
#endif

#ifndef _NETCOMMON_H
#include "NetCommon.h"
#endif

#ifndef _STRDUP_HH
// "strDup()" is used often, so include this here, so everyone gets it:
#include "strDup.hh"
#endif

#ifndef NULL
#define NULL 0
#endif

#ifdef __BORLANDC__
#define _setmode setmode
#define _O_BINARY O_BINARY
#endif

class TaskScheduler; // forward

// An abstract base class, subclassed for each use of the library

class UsageEnvironment {
public:
  void reclaim();

  // task scheduler:
  TaskScheduler& taskScheduler() const {return fScheduler;}

  // result message handling:
  typedef char const* MsgString;
  virtual MsgString getResultMsg() const = 0;

  virtual void setResultMsg(MsgString msg) = 0;
  virtual void setResultMsg(MsgString msg1, MsgString msg2) = 0;
  virtual void setResultMsg(MsgString msg1, MsgString msg2, MsgString msg3) = 0;
  virtual void setResultErrMsg(MsgString msg) = 0;
        // like setResultMsg(), except that an 'errno' message is appended

  virtual void appendToResultMsg(MsgString msg) = 0;

  virtual void reportBackgroundError() = 0;
        // used to report a (previously set) error message within
        // a background event

  // 'errno'
  virtual int getErrno() const = 0;

  // 'console' output:
  virtual UsageEnvironment& operator<<(char const* str) = 0;
  virtual UsageEnvironment& operator<<(int i) = 0;
  virtual UsageEnvironment& operator<<(unsigned u) = 0;
  virtual UsageEnvironment& operator<<(double d) = 0;
  virtual UsageEnvironment& operator<<(void* p) = 0;

  // a pointer to additional, optional, client-specific state
  void* liveMediaPriv;
  void* groupsockPriv;

protected:
  UsageEnvironment(TaskScheduler& scheduler); // abstract base class
  virtual ~UsageEnvironment(); // we are deleted only by reclaim()

private:
  TaskScheduler& fScheduler;
};


typedef void TaskFunc(void* clientData);
typedef void* TaskToken;

class TaskScheduler {
public:
  virtual ~TaskScheduler();

  virtual TaskToken scheduleDelayedTask(int64_t microseconds, TaskFunc* proc,
                                        void* clientData) = 0;
        // Schedules a task to occur (after a delay) when we next
        // reach a scheduling point.
        // (Does not delay if "microseconds" <= 0)
        // Returns a token that can be used in a subsequent call to
        // unscheduleDelayedTask()

  virtual void unscheduleDelayedTask(TaskToken& prevTask) = 0;
        // (Has no effect if "prevTask" == NULL)
        // Sets "prevTask" to NULL afterwards.

  virtual void rescheduleDelayedTask(TaskToken& task,
                                     int64_t microseconds, TaskFunc* proc,
                                     void* clientData);
  // Combines "unscheduleDelayedTask()" with "scheduleDelayedTask()"
  // (setting "task" to the new task token).

  // For handling socket reads in the background:
  typedef void BackgroundHandlerProc(void* clientData, int mask);
    // Possible bits to set in "mask".  (These are deliberately defined
    // the same as those in Tcl, to make a Tcl-based subclass easy.)
    #define SOCKET_READABLE    (1<<1)
    #define SOCKET_WRITABLE    (1<<2)
    #define SOCKET_EXCEPTION   (1<<3)
  virtual void turnOnBackgroundReadHandling(int socketNum,
                                BackgroundHandlerProc* handlerProc,
                                void* clientData) = 0;
  virtual void turnOffBackgroundReadHandling(int socketNum) = 0;

  virtual void doEventLoop(char* watchVariable = NULL) = 0;
        // Stops the current thread of control from proceeding,
        // but allows delayed tasks (and/or background I/O handling)
        // to proceed.
        // (If "watchVariable" is not NULL, then we return from this
        // routine when *watchVariable != 0)

protected:
  TaskScheduler(); // abstract base class
};

#endif

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