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Refactor PingTrackerForRouteSelection

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It's now a special case of new template class PingTrackerBuckets<>.
This is useful so I can vary the bucket size and count.

P4:6894648
This commit is contained in:
Fletcher Dunn
2021-11-12 18:38:10 -08:00
parent 9b794e3077
commit 0d36f6cdd3
1 changed files with 27 additions and 20 deletions
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src/steamnetworkingsockets/steamnetworking_statsutils.h
+27 -20
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@@ -194,30 +194,25 @@ struct PingTrackerDetailed : PingTracker
}
};
/// Before switching to a different route, we need to make sure that we have a ping
/// sample in at least N recent time buckets. (See PingTrackerForRouteSelection)
const int k_nRecentValidTimeBucketsToSwitchRoute = 15;
/// Ping tracker that tracks samples over several intervals. This is used
/// to make routing decisions in such a way to avoid route flapping when ping
/// times on different routes are fluctuating.
///
/// This class also has the concept of a user override, which is used to fake
/// a particular ping time for debugging.
struct PingTrackerForRouteSelection : PingTracker
template<int N, SteamNetworkingMicroseconds W>
struct PingTrackerBuckets : PingTracker
{
COMPILE_TIME_ASSERT( k_nRecentValidTimeBucketsToSwitchRoute == 15 );
static constexpr int k_nTimeBucketCount = 17;
static constexpr SteamNetworkingMicroseconds k_usecTimeBucketWidth = k_nMillion; // Desired width of each time bucket
static constexpr int k_nTimeBucketCount = N;
static constexpr SteamNetworkingMicroseconds k_usecTimeBucketWidth = W; // Desired width of each time bucket
static constexpr int k_nPingOverride_None = -2; // Ordinary operation. (-1 is a legit ping time, which means "ping failed")
static constexpr SteamNetworkingMicroseconds k_usecAntiFlapRouteCheckPingInterval = 200*1000;
struct TimeBucket
{
SteamNetworkingMicroseconds m_usecEnd; // End of this bucket. The start of the bucket is m_usecEnd-k_usecTimeBucketWidth
int m_nPingCount;
int m_nMinPing; // INT_NAX if we have not received one
int m_nMaxPing; // INT_MIN
int m_nMinPing; // INT_MAX if we have not received one
int m_nMaxPing; // INT_MIN if we have not received one
};
TimeBucket m_arTimeBuckets[ k_nTimeBucketCount ];
int m_idxCurrentBucket;
@@ -301,15 +296,6 @@ struct PingTrackerForRouteSelection : PingTracker
curBucket.m_nMaxPing = nPing;
}
/// Return true if the next ping received will start a new bucket
SteamNetworkingMicroseconds TimeToSendNextAntiFlapRouteCheckPingRequest() const
{
return std::min(
m_arTimeBuckets[ m_idxCurrentBucket ].m_usecEnd, // time to start next bucket
m_usecTimeLastSentPingRequest + k_usecAntiFlapRouteCheckPingInterval // and then send them at a given rate
);
}
// Get the min/max ping value among recent buckets.
// Returns the number of valid buckets used to collect the data.
int GetPingRangeFromRecentBuckets( int &nOutMin, int &nOutMax, SteamNetworkingMicroseconds usecNow ) const
@@ -339,6 +325,27 @@ struct PingTrackerForRouteSelection : PingTracker
}
};
/// Before switching to a different route, we need to make sure that we have a ping
/// sample in at least N recent time buckets.
const int k_nRecentValidTimeBucketsToSwitchRoute = 15;
/// Ping tracker for making real-time routing decisions, taking care
/// to avoid flapping due to temporary ping fluctuations
struct PingTrackerForRouteSelection : PingTrackerBuckets<k_nRecentValidTimeBucketsToSwitchRoute+2,k_nMillion>
{
static constexpr SteamNetworkingMicroseconds k_usecAntiFlapRouteCheckPingInterval = 200*1000;
/// Return true if the next ping received will start a new bucket
SteamNetworkingMicroseconds TimeToSendNextAntiFlapRouteCheckPingRequest() const
{
return std::min(
m_arTimeBuckets[ m_idxCurrentBucket ].m_usecEnd, // time to start next bucket
m_usecTimeLastSentPingRequest + k_usecAntiFlapRouteCheckPingInterval // and then send them at a given rate
);
}
};
/// Token bucket rate limiter
/// https://en.wikipedia.org/wiki/Token_bucket
struct TokenBucketRateLimiter