From 23024afb5e6eca38d2fc87ef5941a91ca1490138 Mon Sep 17 00:00:00 2001
From: mikkeljuhl <mikkeljjuhl@gmail.com>
Date: Fri, 27 Apr 2018 08:22:16 +0200
Subject: [PATCH] Move updateUptime to scan.go; don't apply decay when
 calculating host weight

---
 modules/renter/hostdb/consts.go     |  4 ++--
 modules/renter/hostdb/hostweight.go | 32 ++++++++++-------------------
 modules/renter/hostdb/scan.go       | 19 ++++++++++++++++-
 3 files changed, 31 insertions(+), 24 deletions(-)

diff --git a/modules/renter/hostdb/consts.go b/modules/renter/hostdb/consts.go
index d686381225..2fc6b891b0 100644
--- a/modules/renter/hostdb/consts.go
+++ b/modules/renter/hostdb/consts.go
@@ -34,8 +34,8 @@ const (
 	// scans start getting compressed.
 	minScans = 12
 
-	// halftimeUpDownTime is the halftime used to decay the host up and downtime
-	halftimeUpDownTime = 30 * 24 * time.Hour
+	// uptimeHalflife  is the halftime used to decay the host up and downtime
+	uptimeHalflife = 30 * 24 * time.Hour
 
 	// recentInteractionWeightLimit caps the number of recent interactions as a
 	// percentage of the historic interactions, to be certain that a large
diff --git a/modules/renter/hostdb/hostweight.go b/modules/renter/hostdb/hostweight.go
index aaf9702453..1848d70b4f 100644
--- a/modules/renter/hostdb/hostweight.go
+++ b/modules/renter/hostdb/hostweight.go
@@ -1,13 +1,12 @@
 package hostdb
 
 import (
-	"math"
-	"math/big"
-	"time"
-
 	"github.com/NebulousLabs/Sia/build"
 	"github.com/NebulousLabs/Sia/modules"
 	"github.com/NebulousLabs/Sia/types"
+	"math"
+	"math/big"
+	"time"
 )
 
 var (
@@ -323,7 +322,14 @@ func (hdb *HostDB) uptimeAdjustments(entry modules.HostDBEntry) float64 {
 			continue
 		}
 
-		decayUptimeOrDowntime(&entry, scan, recentScan)
+		blocksPassed := scan.BlockHeight - recentScan.BlockHeight
+		timePassed := time.Duration(blocksPassed) * 10 * time.Minute
+
+		if recentScan.Success {
+			uptime += timePassed
+		} else {
+			downtime += timePassed
+		}
 		recentScan = scan
 	}
 	// Sanity check against 0 total time.
@@ -362,22 +368,6 @@ func (hdb *HostDB) uptimeAdjustments(entry modules.HostDBEntry) float64 {
 	return math.Pow(uptimeRatio, exp)
 }
 
-// decayHostUpOrDowntime decays a host's historic uptime or historic downtime.
-// It also adds the new block height to the historic uptime or historic downtime.
-func decayUptimeOrDowntime(entry *modules.HostDBEntry, scan modules.HostDBScan, recentScan modules.HostDBScan) {
-	blocksPassed := scan.BlockHeight - recentScan.BlockHeight
-	timePassed := time.Duration(blocksPassed) * 10 * time.Minute
-	decay := time.Duration(math.Pow(0.5, float64(timePassed)/float64(halftimeUpDownTime)))
-
-	if recentScan.Success {
-		entry.HistoricUptime *= decay
-		entry.HistoricUptime += timePassed * decay
-	} else {
-		entry.HistoricDowntime *= decay
-		entry.HistoricDowntime += timePassed * decay
-	}
-}
-
 // calculateHostWeight returns the weight of a host according to the settings of
 // the host database entry.
 func (hdb *HostDB) calculateHostWeight(entry modules.HostDBEntry) types.Currency {
diff --git a/modules/renter/hostdb/scan.go b/modules/renter/hostdb/scan.go
index 13edae56f2..c96988887d 100644
--- a/modules/renter/hostdb/scan.go
+++ b/modules/renter/hostdb/scan.go
@@ -13,8 +13,25 @@ import (
 	"github.com/NebulousLabs/Sia/encoding"
 	"github.com/NebulousLabs/Sia/modules"
 	"github.com/NebulousLabs/fastrand"
+	"math"
 )
 
+// updateUptime decays a host's historic uptime or historic downtime.
+// It also adds the new block height to the historic uptime or historic downtime.
+func updateUptime(entry *modules.HostDBEntry, scan modules.HostDBScan, recentScan modules.HostDBScan) {
+	blocksPassed := scan.BlockHeight - recentScan.BlockHeight
+	timePassed := time.Duration(blocksPassed) * 10 * time.Minute
+	decay := time.Duration(math.Pow(0.5, float64(timePassed)/float64(uptimeHalflife)))
+	entry.HistoricUptime *= decay
+	entry.HistoricDowntime *= decay
+
+	if recentScan.Success {
+		entry.HistoricUptime += timePassed * decay
+	} else {
+		entry.HistoricDowntime += timePassed * decay
+	}
+}
+
 // queueScan will add a host to the queue to be scanned.
 func (hdb *HostDB) queueScan(entry modules.HostDBEntry) {
 	// If this entry is already in the scan pool, can return immediately.
@@ -207,7 +224,7 @@ func (hdb *HostDB) updateEntry(entry modules.HostDBEntry, netErr error) {
 
 	// Compress any old scans into the historic values.
 	for len(newEntry.ScanHistory) > minScans && time.Now().Sub(newEntry.ScanHistory[0].Timestamp) > maxHostDowntime {
-		decayUptimeOrDowntime(&newEntry, newEntry.ScanHistory[1], newEntry.ScanHistory[0])
+		updateUptime(&newEntry, newEntry.ScanHistory[1], newEntry.ScanHistory[0])
 		newEntry.ScanHistory = newEntry.ScanHistory[1:]
 	}