private void SetWeightedAverageResponseTime(HostEntry h)
{
var value = 0f;
var lastValue = 0f;
var prevIndex = (h.EpsilonIndex - 1) % EpsilonBuckets; //capture the current index
//start from 2, skipping the current epsilon index
for (var i = 2; i <= EpsilonBuckets; i++)
{
var pos = (prevIndex + i) % EpsilonBuckets;
var counts = h.EpsilonCounts[pos];
// Changing the line below to what I think it should be to get the weights right
var weight = weights[i - 1];
if (counts > 0)
{
//the average
//var currentValue = h.EpsilonValues[pos] / Convert.ToSingle(counts);
var currentValue = h.EpsilonAvg[pos];
value += currentValue * weight;
lastValue = currentValue;
}
else
{
value += lastValue * weight;
}
}
h.EpsilonWeightAverage = value;
}
public virtual void AddHost(string host, Connection conn)
{
lock ( hostLock )
{
if (shuttingDown)
{
return;
}
var oldHostList = this.hostList;
var nextHostList = new HostEntry[oldHostList.Length + 1];
Array.Copy(oldHostList, nextHostList, oldHostList.Length);
//add new host to the end of the array. Initially, start off as a dead
//host.
var he = new HostEntry(host)
{
conn = conn,
Dead = true,
RetryDelayInitial = RetryDelayInitial,
RetryDelayMax = RetryDelayMax
};
nextHostList[nextHostList.Length - 1] = he;
this.hostList = nextHostList;
}
}
internal void MarkSuccess(HostEntry h, long start, long end)
{
var duration = TimeSpan.FromTicks(end - start);
var index = h.EpsilonIndex % EpsilonBuckets;
var counts = h.EpsilonCounts;
var values = h.EpsilonValues;
Interlocked.Increment(ref counts[index]);
Interlocked.Add(ref values[index], Convert.ToInt64(duration.TotalMilliseconds));
}
public override async Task <string> RunResultAsRawJson(ReqlAst term, object globalOpts, CancellationToken cancelToken)
{
HostEntry host = GetRoundRobin();
try {
return(await host.conn.RunResultAsRawJson(term, globalOpts, cancelToken).ConfigureAwait(false));
}
catch (Exception e) when(ExceptionIs.NetworkError(e))
{
host.MarkFailed();
throw;
}
}
public override void RunNoReply(ReqlAst term, object globalOpts)
{
HostEntry host = GetRoundRobin();
try
{
host.conn.RunNoReply(term, globalOpts);
}
catch (Exception e) when(ExceptionIs.NetworkError(e))
{
host.MarkFailed();
throw;
}
}
public override void RunNoReply(ReqlAst term, object globalOpts)
{
HostEntry host = GetEpsilonGreedy();
try
{
var start = DateTime.Now.Ticks;
host.conn.RunNoReply(term, globalOpts);
var end = DateTime.Now.Ticks;
MarkSuccess(host, start, end);
}
catch (Exception e) when(ExceptionIs.NetworkError(e))
{
host.MarkFailed();
throw;
}
}
public override async Task <Cursor <T> > RunCursorAsync <T>(ReqlAst term, object globalOpts, CancellationToken cancelToken)
{
HostEntry host = GetEpsilonGreedy();
try
{
var start = DateTime.Now.Ticks;
var result = await host.conn.RunCursorAsync <T>(term, globalOpts, cancelToken).ConfigureAwait(false);
var end = DateTime.Now.Ticks;
MarkSuccess(host, start, end);
return(result);
}
catch (Exception e) when(ExceptionIs.NetworkError(e))
{
host.MarkFailed();
throw;
}
}
internal virtual HostEntry GetEpsilonGreedy()
{
HostEntry hostToUse = null;
//this is our exploration phase
var rand = Random.NextDouble();
if (rand < this.epsilon)
{
this.epsilon = this.epsilon * EpsilonDecay;
if (this.epsilon < MinEpsilon)
{
this.epsilon = MinEpsilon;
}
return(this.GetRoundRobin());
}
var hlist = this.hostList;
var ceiling = 0.0d;
//find best.
for (var i = 0; i < hlist.Length; i++)
{
var h = hlist[i];
if (!h.Dead && h.EpsilonWeightAverage > 0)
{
ceiling += h.EpsilonPercentage;
if (rand <= ceiling)
{
hostToUse = h;
break;
}
}
}
if (hostToUse == null || hostToUse.Dead)
{
return(this.GetRoundRobin());
}
return(hostToUse);
}
public void failure_should_double_retry()
{
var he = new HostEntry("a")
{
RetryDelayMax = TimeSpan.FromSeconds(300),
RetryDelayInitial = TimeSpan.FromSeconds(30)
};
he.MarkFailed();
he.Dead.Should().BeTrue();
he.RetryCount.Should().Be(0);
he.NextRetry.Should().BeCloseTo(DateTime.Now.AddSeconds(30), precision: 3000);
he.RetryFailed();
he.RetryCount.Should().Be(1);
he.NextRetry.Should().BeCloseTo(DateTime.Now.AddSeconds(30 * 2), precision: 3000);
he.RetryFailed();
he.RetryCount.Should().Be(2);
he.NextRetry.Should().BeCloseTo(DateTime.Now.AddSeconds(30 * 2 * 2), precision: 3000);
//run it past the maximum
Enumerable.Range(1, 30 * 12)
.ForEach(i => he.RetryFailed());
he.RetryFailed();
he.NextRetry.Should().BeCloseTo(DateTime.Now + he.RetryDelayMax, precision: 1000);
}
private void SetEpsilonValue(HostEntry h)
{
h.EpsilonValue = this.calc.CalcValueFromAvgResponseTime(h.EpsilonWeightAverage);
}
