BasicUsageEnvironment/BasicTaskScheduler0.cpp

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This library is distributed in the hope that it will be useful, but WITHOUT
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FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for
more details.

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// Copyright (c) 1996-2008 Live Networks, Inc.  All rights reserved.
// Basic Usage Environment: for a simple, non-scripted, console application
// Implementation

#include "BasicUsageEnvironment0.hh"
#include "HandlerSet.hh"


class AlarmHandler: public DelayQueueEntry {
public:
  AlarmHandler(TaskFunc* proc, void* clientData, DelayInterval timeToDelay)
    : DelayQueueEntry(timeToDelay), fProc(proc), fClientData(clientData) {
  }

private: // redefined virtual functions
  virtual void handleTimeout() {
    (*fProc)(fClientData);
    DelayQueueEntry::handleTimeout();
  }

private:
  TaskFunc* fProc;
  void* fClientData;
};



BasicTaskScheduler0::BasicTaskScheduler0()
  : fLastHandledSocketNum(-1) {
  fReadHandlers = new HandlerSet;
}

BasicTaskScheduler0::~BasicTaskScheduler0() {
  delete fReadHandlers;
}

TaskToken BasicTaskScheduler0::scheduleDelayedTask(int64_t microseconds,
                                                 TaskFunc* proc,
                                                 void* clientData) {
  if (microseconds < 0) microseconds = 0;
  DelayInterval timeToDelay((long)(microseconds/1000000), (long)(microseconds%1000000));
  AlarmHandler* alarmHandler = new AlarmHandler(proc, clientData, timeToDelay);
  fDelayQueue.addEntry(alarmHandler);

  return (void*)(alarmHandler->token());
}

void BasicTaskScheduler0::unscheduleDelayedTask(TaskToken& prevTask) {
  DelayQueueEntry* alarmHandler = fDelayQueue.removeEntry((long)prevTask);
  prevTask = NULL;
  delete alarmHandler;
}

void BasicTaskScheduler0::doEventLoop(char* watchVariable) {
  // Repeatedly loop, handling readble sockets and timed events:
  while (1) {
    if (watchVariable != NULL && *watchVariable != 0) break;
    SingleStep();
  }
}



HandlerDescriptor::HandlerDescriptor(HandlerDescriptor* nextHandler) {
  // Link this descriptor into a doubly-linked list:
  if (nextHandler == this) { // initialization
    fNextHandler = fPrevHandler = this;
  } else {
    fNextHandler = nextHandler;
    fPrevHandler = nextHandler->fPrevHandler;
    nextHandler->fPrevHandler = this;
    fPrevHandler->fNextHandler = this;
  }
}

HandlerDescriptor::~HandlerDescriptor() {
  // Unlink this descriptor from a doubly-linked list:
  fNextHandler->fPrevHandler = fPrevHandler;
  fPrevHandler->fNextHandler = fNextHandler;
}

HandlerSet::HandlerSet()
  : fHandlers(&fHandlers) {
  fHandlers.socketNum = -1; // shouldn't ever get looked at, but in case...
}

HandlerSet::~HandlerSet() {
  // Delete each handler descriptor:
  while (fHandlers.fNextHandler != &fHandlers) {
    delete fHandlers.fNextHandler; // changes fHandlers->fNextHandler
  }
}

void HandlerSet
::assignHandler(int socketNum,
                TaskScheduler::BackgroundHandlerProc* handlerProc,
                void* clientData) {
  // First, see if there's already a handler for this socket:
  HandlerDescriptor* handler;
  HandlerIterator iter(*this);
  while ((handler = iter.next()) != NULL) {
    if (handler->socketNum == socketNum) break;
  }
  if (handler == NULL) { // No existing handler, so create a new descr:
    handler = new HandlerDescriptor(fHandlers.fNextHandler);
    handler->socketNum = socketNum;
  }

  handler->handlerProc = handlerProc;
  handler->clientData = clientData;
}

void HandlerSet::removeHandler(int socketNum) {
  HandlerDescriptor* handler;
  HandlerIterator iter(*this);
  while ((handler = iter.next()) != NULL) {
    if (handler->socketNum == socketNum) {
      delete handler;
      break;
    }
  }
}

HandlerIterator::HandlerIterator(HandlerSet& handlerSet)
  : fOurSet(handlerSet) {
  reset();
}

HandlerIterator::~HandlerIterator() {
}

void HandlerIterator::reset() {
  fNextPtr = fOurSet.fHandlers.fNextHandler;
}

HandlerDescriptor* HandlerIterator::next() {
  HandlerDescriptor* result = fNextPtr;
  if (result == &fOurSet.fHandlers) { // no more
    result = NULL;
  } else {
    fNextPtr = fNextPtr->fNextHandler;
  }

  return result;
}

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