src/AsyncCallQueue.cc

   1
   2 /*
   3  * $Id: AsyncCallQueue.cc,v 1.1 2008/02/13 06:01:39 rousskov Exp $
   4  *
   5  * DEBUG: section 41    Event Processing
   6  *
   7  */
   8
   9 #include "AsyncCallQueue.h"
  10 #include "AsyncCall.h"
  11
  12 AsyncCallQueue *AsyncCallQueue::TheInstance = 0;
  13
  14
  15 AsyncCallQueue::AsyncCallQueue(): theHead(NULL), theTail(NULL)
  16 {
  17 }
  18
  19 void AsyncCallQueue::schedule(AsyncCall::Pointer &call)
  20 {
  21     assert(call != NULL);
  22     assert(!call->theNext);
  23     if (theHead != NULL) { // append
  24         assert(!theTail->theNext);
  25         theTail->theNext = call;
  26         theTail = call;
  27     } else { // create queue from cratch
  28         theHead = theTail = call;
  29     }
  30 }
  31
  32 // Fire all scheduled calls; returns true if at least one call was fired.
  33 // The calls may be added while the current call is in progress.
  34 bool
  35 AsyncCallQueue::fire()
  36 {
  37     const bool made = theHead != NULL;
  38     while (theHead != NULL)
  39         fireNext();
  40     return made;
  41 }
  42
  43 void
  44 AsyncCallQueue::fireNext()
  45 {
  46     AsyncCall::Pointer call = theHead;
  47     theHead = call->theNext;
  48     call->theNext = NULL;
  49     if (theTail == call)
  50         theTail = NULL;
  51
  52     debugs(call->debugSection, call->debugLevel, "entering " << *call);
  53     call->make();
  54     debugs(call->debugSection, call->debugLevel, "leaving " << *call);
  55 }
  56
  57 AsyncCallQueue &
  58 AsyncCallQueue::Instance()
  59 {
  60     // TODO: how to remove this frequent check while supporting early calls?
  61     if (!TheInstance)
  62         TheInstance = new AsyncCallQueue();
  63
  64     return *TheInstance;
  65 }
  66