src/base/AsyncCallQueue.cc

   1
   2 /*
   3  * $Id$
   4  *
   5  * DEBUG: section 41    Event Processing
   6  *
   7  */
   8
   9 #include "config.h"
  10 #include "base/AsyncCallQueue.h"
  11 #include "base/AsyncCall.h"
  12
  13 AsyncCallQueue *AsyncCallQueue::TheInstance = 0;
  14
  15
  16 AsyncCallQueue::AsyncCallQueue(): theHead(NULL), theTail(NULL)
  17 {
  18 }
  19
  20 void AsyncCallQueue::schedule(AsyncCall::Pointer &call)
  21 {
  22     assert(call != NULL);
  23     assert(!call->theNext);
  24     if (theHead != NULL) { // append
  25         assert(!theTail->theNext);
  26         theTail->theNext = call;
  27         theTail = call;
  28     } else { // create queue from cratch
  29         theHead = theTail = call;
  30     }
  31 }
  32
  33 // Fire all scheduled calls; returns true if at least one call was fired.
  34 // The calls may be added while the current call is in progress.
  35 bool
  36 AsyncCallQueue::fire()
  37 {
  38     const bool made = theHead != NULL;
  39     while (theHead != NULL)
  40         fireNext();
  41     return made;
  42 }
  43
  44 void
  45 AsyncCallQueue::fireNext()
  46 {
  47     AsyncCall::Pointer call = theHead;
  48     theHead = call->theNext;
  49     call->theNext = NULL;
  50     if (theTail == call)
  51         theTail = NULL;
  52
  53     debugs(call->debugSection, call->debugLevel, "entering " << *call);
  54     call->make();
  55     debugs(call->debugSection, call->debugLevel, "leaving " << *call);
  56 }
  57
  58 AsyncCallQueue &
  59 AsyncCallQueue::Instance()
  60 {
  61     // TODO: how to remove this frequent check while supporting early calls?
  62     if (!TheInstance)
  63         TheInstance = new AsyncCallQueue();
  64
  65     return *TheInstance;
  66 }
  67