From 8abd2050fad3a35a0eb465233786dc9baf90e0c0 Mon Sep 17 00:00:00 2001
From: James Phillips <slackpad@gmail.com>
Date: Wed, 29 Nov 2017 10:34:24 -0800
Subject: [PATCH] Sheds monotonic time info so tombstone GC bins work properly.

---
 agent/consul/state/tombstone_gc.go      |  4 +++-
 agent/consul/state/tombstone_gc_test.go | 13 ++++++++-----
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/agent/consul/state/tombstone_gc.go b/agent/consul/state/tombstone_gc.go
index 459321bda3..3b141c2bdf 100644
--- a/agent/consul/state/tombstone_gc.go
+++ b/agent/consul/state/tombstone_gc.go
@@ -135,7 +135,9 @@ func (t *TombstoneGC) PendingExpiration() bool {
 // granularity that is set. This allows us to bin expirations and avoid a ton
 // of timers.
 func (t *TombstoneGC) nextExpires() time.Time {
-	expires := time.Now().Add(t.ttl)
+	// The Round(0) call here is to shed the monotonic time so that we
+	// can safely use these as map keys. See #3670 for more details.
+	expires := time.Now().Add(t.ttl).Round(0)
 	remain := expires.UnixNano() % int64(t.granularity)
 	adj := expires.Add(t.granularity - time.Duration(remain))
 	return adj
diff --git a/agent/consul/state/tombstone_gc_test.go b/agent/consul/state/tombstone_gc_test.go
index b05d0c2773..d1aa5581d6 100644
--- a/agent/consul/state/tombstone_gc_test.go
+++ b/agent/consul/state/tombstone_gc_test.go
@@ -1,7 +1,6 @@
 package state
 
 import (
-	"os"
 	"testing"
 	"time"
 )
@@ -24,10 +23,6 @@ func TestTombstoneGC_invalid(t *testing.T) {
 }
 
 func TestTombstoneGC(t *testing.T) {
-	if os.Getenv("TRAVIS") == "true" {
-		t.Skip("GC test is flaky on travis-ci (see #3670)")
-	}
-
 	ttl := 20 * time.Millisecond
 	gran := 5 * time.Millisecond
 	gc, err := NewTombstoneGC(ttl, gran)
@@ -65,6 +60,14 @@ func TestTombstoneGC(t *testing.T) {
 	gc.Hint(120)
 	gc.Hint(125)
 
+	// Check that we only have a single bin (this cross-checks #3670).
+	gc.Lock()
+	bins := len(gc.expires)
+	gc.Unlock()
+	if got, want := bins, 1; got != want {
+		t.Fatalf("got %d want %d", got, want)
+	}
+
 	if !gc.PendingExpiration() {
 		t.Fatalf("should be pending")
 	}