From cd577f605948894b51fbaab39d1df03a04dfd70f Mon Sep 17 00:00:00 2001
From: Akanksha Mahajan <43301668+akankshamahajan15@users.noreply.github.com>
Date: Thu, 14 Dec 2023 13:45:06 -0800
Subject: [PATCH] Fix WRITE_STALL start_time (#12147)

Summary:
`Delayed` is set true in two cases. One is when `delay` is specified. Other one is in the `while` loop - https://github.com/facebook/rocksdb/blob/cd21e4e69d76ec4ec3b080c8cdae016ac2309cc5/db/db_impl/db_impl_write.cc#L1876
However start_time is not initialized in second case, resulting in time_delayed = immutable_db_options_.clock->NowMicros() - 0(start_time);

Pull Request resolved: https://github.com/facebook/rocksdb/pull/12147

Test Plan: Existing CircleCI

Reviewed By: cbi42

Differential Revision: D52173481

Pulled By: akankshamahajan15

fbshipit-source-id: fb9183b24c191d287a1d715346467bee66190f98
---
 db/db_impl/db_impl_write.cc                       | 3 ++-
 unreleased_history/bug_fixes/fix_stall_counter.md | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)
 create mode 100644 unreleased_history/bug_fixes/fix_stall_counter.md

diff --git a/db/db_impl/db_impl_write.cc b/db/db_impl/db_impl_write.cc
index 8add1e990b7..df67ba8c8f1 100644
--- a/db/db_impl/db_impl_write.cc
+++ b/db/db_impl/db_impl_write.cc
@@ -1839,11 +1839,12 @@ Status DBImpl::DelayWrite(uint64_t num_bytes, WriteThread& write_thread,
       delay = 0;
     }
     TEST_SYNC_POINT("DBImpl::DelayWrite:Start");
+    start_time = immutable_db_options_.clock->NowMicros();
+
     if (delay > 0) {
       if (write_options.no_slowdown) {
         return Status::Incomplete("Write stall");
       }
-      start_time = immutable_db_options_.clock->NowMicros();
       TEST_SYNC_POINT("DBImpl::DelayWrite:Sleep");
 
       // Notify write_thread about the stall so it can setup a barrier and
diff --git a/unreleased_history/bug_fixes/fix_stall_counter.md b/unreleased_history/bug_fixes/fix_stall_counter.md
new file mode 100644
index 00000000000..be9e5122f8d
--- /dev/null
+++ b/unreleased_history/bug_fixes/fix_stall_counter.md
@@ -0,0 +1 @@
+Fix a WRITE_STALL counter that was reporting wrong value in few cases.