first cut at multi-threading version
This commit is contained in:
Jeff Hill
348
src/ca/searchTimer.cpp
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348
src/ca/searchTimer.cpp
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/* * $Id$
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*
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* L O S A L A M O S
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* Los Alamos National Laboratory
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* Los Alamos, New Mexico 87545
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*
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* Copyright, 1986, The Regents of the University of California.
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*
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* Author: Jeff Hill
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*/
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#include "iocinf.h"
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//
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// searchTimer::searchTimer ()
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//
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searchTimer::searchTimer (udpiiu &iiuIn, osiTimerQueue &queueIn) :
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osiTimer (queueIn),
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iiu (iiuIn),
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framesPerTry (INITIALTRIESPERFRAME),
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framesPerTryCongestThresh (UINT_MAX),
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minRetry (UINT_MAX),
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retry (0u),
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searchTries (0u),
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searchResponses (0u),
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retrySeqNo (0u),
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retrySeqNoAtListBegin (0u),
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period (CA_RECAST_DELAY)
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{
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}
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//
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// searchTimer::reset ()
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//
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void searchTimer::reset (double period)
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{
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LOCK (this->iiu.niiu.iiu.pcas);
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this->retry = 0;
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this->period = period;
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UNLOCK (this->iiu.niiu.iiu.pcas);
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if (this->timeRemaining()>period) {
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this->reschedule (0.0);
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}
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}
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/*
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* searchTimer::setRetryInterval ()
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*/
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void searchTimer::setRetryInterval (unsigned retryNo)
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{
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unsigned idelay;
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double delay;
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LOCK (this->iiu.niiu.iiu.pcas);
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/*
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* set the retry number
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*/
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this->retry = min (retryNo, MAXCONNTRIES+1u);
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/*
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* set the retry interval
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*/
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idelay = 1u << min (this->retry, CHAR_BIT*sizeof(idelay)-1u);
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delay = idelay * CA_RECAST_DELAY; /* sec */
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/*
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* place upper limit on the retry delay
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*/
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this->period = min (CA_RECAST_PERIOD, delay);
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UNLOCK (this->iiu.niiu.iiu.pcas);
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#ifdef DEBUG
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printf ("new CA search period is %f sec\n", this->period);
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#endif
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}
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//
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// searchTimer::notifySearchResponse ()
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//
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// Reset the delay to the next search request if we get
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// at least one response. However, dont reset this delay if we
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// get a delayed response to an old search request.
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//
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void searchTimer::notifySearchResponse (nciu *pChan)
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{
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LOCK (this->iiu.niiu.iiu.pcas);
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if ( this->retrySeqNoAtListBegin <= pChan->retrySeqNo ) {
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if ( this->searchResponses < ULONG_MAX ) {
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this->searchResponses++;
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}
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}
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UNLOCK (this->iiu.niiu.iiu.pcas);
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if (pChan->retrySeqNo == this->retrySeqNo) {
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this->reschedule (0.0);
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}
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}
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//
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// searchTimer::expire ()
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//
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void searchTimer::expire ()
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{
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nciu *chan;
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nciu *firstChan;
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int status;
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unsigned nSent=0u;
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/*
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* check to see if there is nothing to do here
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*/
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if (ellCount(&this->iiu.niiu.chidList)==0) {
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return;
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}
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LOCK (this->iiu.niiu.iiu.pcas);
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/*
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* increment the retry sequence number
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*/
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this->retrySeqNo++; /* allowed to roll over */
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/*
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* dynamically adjust the number of UDP frames per
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* try depending how many search requests are not
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* replied to
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*
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* This determines how many search request can be
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* sent together (at the same instant in time).
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*
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* The variable this->framesPerTry
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* determines the number of UDP frames to be sent
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* each time that retrySearchRequest() is called.
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* If this value is too high we will waste some
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* network bandwidth. If it is too low we will
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* use very little of the incoming UDP message
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* buffer associated with the server's port and
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* will therefore take longer to connect. We
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* initialize this->framesPerTry
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* to a prime number so that it is less likely that the
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* same channel is in the last UDP frame
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* sent every time that this is called (and
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* potentially discarded by a CA server with
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* a small UDP input queue).
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*/
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/*
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* increase frames per try only if we see better than
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* a 93.75% success rate for one pass through the list
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*/
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if (this->searchResponses >
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(this->searchTries-(this->searchTries/16u)) ) {
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/*
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* increase UDP frames per try if we have a good score
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*/
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if ( this->framesPerTry < MAXTRIESPERFRAME ) {
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/*
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* a congestion avoidance threshold similar to TCP is now used
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*/
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if ( this->framesPerTry < this->framesPerTryCongestThresh ) {
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this->framesPerTry += this->framesPerTry;
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}
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else {
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this->framesPerTry += (this->framesPerTry/8) + 1;
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}
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#if 0
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printf ("Increasing frame count to %u t=%u r=%u\n",
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this->framesPerTry, this->searchTries,
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this->searchResponses);
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#endif
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}
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}
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/*
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* if we detect congestion because we have less than a 87.5% success
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* rate then gradually reduce the frames per try
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*/
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else if ( this->searchResponses <
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(this->searchTries-(this->searchTries/8u)) ) {
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if (this->framesPerTry>1) {
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this->framesPerTry--;
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}
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this->framesPerTryCongestThresh = this->framesPerTry/2 + 1;
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#if 0
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printf ("Congestion detected - set frames per try to %u t=%u r=%u\n",
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this->framesPerTry, this->searchTries,
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this->searchResponses);
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#endif
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}
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/*
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* a successful cac_search_msg() sends channel to
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* the end of the list
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*/
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firstChan = chan = (nciu *) ellFirst (&this->iiu.niiu.chidList);
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while (chan) {
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this->minRetry = min (this->minRetry, chan->retry);
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/*
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* clear counter when we reach the end of the list
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*
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* if we are making some progress then
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* dont increase the delay between search
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* requests
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*/
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if ( this->iiu.niiu.iiu.pcas->ca_pEndOfBCastList == chan ) {
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if ( this->searchResponses == 0u ) {
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#if 0
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printf ("increasing search try interval\n");
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#endif
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this->setRetryInterval (this->minRetry + 1u);
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}
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this->minRetry = UINT_MAX;
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/*
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* increment the retry sequence number
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* (this prevents the time of the next search
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* try from being set to the current time if
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* we are handling a response from an old
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* search message)
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*/
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this->retrySeqNo++; /* allowed to roll over */
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/*
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* so that old search tries will not update the counters
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*/
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this->retrySeqNoAtListBegin = this->retrySeqNo;
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/*
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* reset the search try/response counters at the end of the list
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* (sequence number) so that we dont overflow, but dont subtract
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* out tries that dont have a matching response yet in case they
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* are delayed
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*/
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if ( this->searchTries > this->searchResponses ) {
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this->searchTries -= this->searchResponses;
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}
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else {
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this->searchTries = 0;
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}
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this->searchResponses = 0;
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#if 0
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printf ("saw end of list\n");
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#endif
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}
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/*
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* this moves the channel to the end of the
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* list (if successful)
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*/
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status = cac_search_msg (chan);
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if (status != ECA_NORMAL) {
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nSent++;
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if (nSent>=this->framesPerTry) {
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break;
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}
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/* flush out the search request buffer */
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semBinaryGive (this->iiu.xmitSignal);
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/* try again */
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status = cac_search_msg (chan);
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if (status != ECA_NORMAL) {
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break;
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}
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}
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if (this->searchTries<ULONG_MAX) {
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this->searchTries++;
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}
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chan->retrySeqNo = this->retrySeqNo;
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chan = (nciu *) ellFirst (&this->iiu.niiu.chidList);
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/*
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* dont send any of the channels twice within one try
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*/
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if (chan==firstChan) {
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/*
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* add one to nSent because there may be
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* one more partial frame to be sent
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*/
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nSent++;
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/*
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* cap this->framesPerTry to
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* the number of frames required for all of
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* the unresolved channels
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*/
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if (this->framesPerTry>nSent) {
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this->framesPerTry = nSent;
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}
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break;
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}
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}
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UNLOCK (this->iiu.niiu.iiu.pcas);
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/* flush out the search request buffer */
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semBinaryGive (this->iiu.xmitSignal);
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#ifdef DEBUG
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printf ("sent %u delay sec=%f\n", nSent, this->period);
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#endif
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}
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void searchTimer::destroy ()
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{
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}
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bool searchTimer::again () const
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{
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if (ellCount(&this->iiu.niiu.chidList)==0) {
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return false;
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}
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else {
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if (this->retry < MAXCONNTRIES) {
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return true;
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}
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else {
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return false;
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}
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}
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}
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double searchTimer::delay () const
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{
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return this->period;
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}
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void searchTimer::show (unsigned level) const
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{
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}
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const char *searchTimer::name () const
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{
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return "CAC Search Timer";
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}
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