From dc3686f79b3750500efaff7092c81a3e5ce6d02c Mon Sep 17 00:00:00 2001
From: Tobias Schottdorf <tobias.schottdorf@gmail.com>
Date: Wed, 14 Aug 2019 11:26:56 +0200
Subject: [PATCH] kv: init heartbeat txn log tag later

At init() time, the txn proto has not been populated yet.
Found while investigating #39652.

Release note: None
---
 pkg/kv/txn_interceptor_heartbeater.go | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/pkg/kv/txn_interceptor_heartbeater.go b/pkg/kv/txn_interceptor_heartbeater.go
index 5f7dc1d0455f..7c77fe4d568a 100644
--- a/pkg/kv/txn_interceptor_heartbeater.go
+++ b/pkg/kv/txn_interceptor_heartbeater.go
@@ -115,7 +115,6 @@ func (h *txnHeartbeater) init(
 	asyncAbortCallbackLocked func(context.Context),
 ) {
 	h.AmbientContext = ac
-	h.AmbientContext.AddLogTag("txn-hb", txn.Short())
 	h.stopper = stopper
 	h.clock = clock
 	h.heartbeatInterval = heartbeatInterval
@@ -208,6 +207,9 @@ func (h *txnHeartbeater) startHeartbeatLoopLocked(ctx context.Context) error {
 	log.VEventf(ctx, 2, "coordinator spawns heartbeat loop")
 	h.mu.loopStarted = true
 	h.mu.txnEnd = make(chan struct{})
+	// NB: we can't do this in init() because the txn isn't populated yet then
+	// (it's zero).
+	h.AmbientContext.AddLogTag("txn-hb", h.mu.txn.Short())
 
 	// Create a new context so that the heartbeat loop doesn't inherit the
 	// caller's cancelation.