From 32fdeefe13b122fb25e3cba85699677b04c15f3d Mon Sep 17 00:00:00 2001
From: "Penn (Dapeng) Zhang" <zdapeng@google.com>
Date: Mon, 15 Nov 2021 13:08:08 -0800
Subject: [PATCH] census: fix NPE in calling recordFinishedAttempt()

---
 .../src/main/java/io/grpc/census/CensusStatsModule.java   | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/census/src/main/java/io/grpc/census/CensusStatsModule.java b/census/src/main/java/io/grpc/census/CensusStatsModule.java
index 4b2832c5989..fa72384a3e5 100644
--- a/census/src/main/java/io/grpc/census/CensusStatsModule.java
+++ b/census/src/main/java/io/grpc/census/CensusStatsModule.java
@@ -342,9 +342,6 @@ public void outboundMessage(int seqNo) {
 
     @Override
     public void streamClosed(Status status) {
-      attemptsState.attemptEnded();
-      stopwatch.stop();
-      roundtripNanos = stopwatch.elapsed(TimeUnit.NANOSECONDS);
       Deadline deadline = info.getCallOptions().getDeadline();
       statusCode = status.getCode();
       if (statusCode == Status.Code.CANCELLED && deadline != null) {
@@ -355,6 +352,9 @@ public void streamClosed(Status status) {
           statusCode = Code.DEADLINE_EXCEEDED;
         }
       }
+      attemptsState.attemptEnded();
+      stopwatch.stop();
+      roundtripNanos = stopwatch.elapsed(TimeUnit.NANOSECONDS);
       if (inboundReceivedOrClosed.compareAndSet(false, true)) {
         if (module.recordFinishedRpcs) {
           // Stream is closed early. So no need to record metrics for any inbound events after this
@@ -522,6 +522,8 @@ void recordFinishedCall() {
         tracer.statusCode = status.getCode();
         tracer.recordFinishedAttempt();
       } else if (inboundMetricTracer != null) {
+        // activeStreams has been decremented to 0 by attemptEnded(),
+        // so inboundMetricTracer.statusCode is guaranteed to be assigned already.
         inboundMetricTracer.recordFinishedAttempt();
       }
       if (!module.recordRetryMetrics) {