From 20f826df7ff9305cba7d97f5145e8e21c130b1af Mon Sep 17 00:00:00 2001
From: Martin Dyring-Andersen <martin@dyring-andersen.dk>
Date: Tue, 20 Oct 2020 14:14:56 +0200
Subject: [PATCH] Only slash after signedBlocksWindow has passed

Closes #19
---
 x/slashing/abci.go   | 23 ++++++++++++-----------
 x/slashing/keeper.go |  9 +++++++--
 2 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/x/slashing/abci.go b/x/slashing/abci.go
index 367f2fb0..8891c360 100644
--- a/x/slashing/abci.go
+++ b/x/slashing/abci.go
@@ -24,7 +24,7 @@ func BeginBlocker(ctx sdk.Context, req abci.RequestBeginBlock, sk Keeper, batch
 
 	blockTimes := sk.getBlockTimes()
 	blockTimes = append(blockTimes, ctx.BlockTime())
-	blockTimes = truncateByWindow(ctx.BlockTime(), blockTimes, signedBlocksWindow)
+	_, blockTimes = truncateByWindow(ctx.BlockTime(), blockTimes, signedBlocksWindow)
 	sk.setBlockTimes(batch, blockTimes)
 
 	sk.handlePendingPenalties(ctx, batch, validatorset(req.LastCommitInfo.Votes))
@@ -61,17 +61,18 @@ func validatorset(validators []abci.VoteInfo) func() map[string]bool {
 	}
 }
 
-func truncateByWindow(blockTime time.Time, times []time.Time, signedBlocksWindow time.Duration) []time.Time {
-	if len(times) == 0 {
-		return times
-	}
+func truncateByWindow(blockTime time.Time, times []time.Time, signedBlocksWindow time.Duration) (bool, []time.Time) {
+
+	if len(times) > 0 && times[0].Add(signedBlocksWindow).Before(blockTime) {
+		// Remove timestamps outside of the time window we are watching
+		threshold := blockTime.Add(-signedBlocksWindow)
 
-	// Remove timestamps outside of the time window we are watching
-	threshold := blockTime.Add(-1 * signedBlocksWindow)
+		index := sort.Search(len(times), func(i int) bool {
+			return times[i].After(threshold)
+		})
 
-	index := sort.Search(len(times), func(i int) bool {
-		return times[i].After(threshold)
-	})
+		return true, times[index:]
+	}
 
-	return times[index:]
+	return false, times
 }
diff --git a/x/slashing/keeper.go b/x/slashing/keeper.go
index aabd3e44..f200370f 100644
--- a/x/slashing/keeper.go
+++ b/x/slashing/keeper.go
@@ -167,15 +167,20 @@ func (k Keeper) HandleValidatorSignature(ctx sdk.Context, batch db.Batch, addr c
 	consAddr := sdk.ConsAddress(addr)
 
 	missedBlocks := k.getMissingBlocksForValidator(consAddr)
-	missedBlocks = truncateByWindow(ctx.BlockTime(), missedBlocks, k.SignedBlocksWindowDuration(ctx))
+	truncated, missedBlocks := truncateByWindow(ctx.BlockTime(), missedBlocks, k.SignedBlocksWindowDuration(ctx))
 
 	if !signed {
 		missedBlocks = append(missedBlocks, ctx.BlockTime())
 	}
 
 	k.setMissingBlocksForValidator(batch, consAddr, missedBlocks)
-	missedBlockCount := sdk.NewInt(int64(len(missedBlocks))).ToDec()
 
+	// Validator is only slashable if the signed block window is full (was truncated)
+	if !truncated {
+		return
+	}
+
+	missedBlockCount := sdk.NewInt(int64(len(missedBlocks))).ToDec()
 	missedRatio := missedBlockCount.QuoInt64(blockCount)
 
 	// TODO Only do this if missing is true?