From 77192f102c5fab595119c67d764fb4a009f98e35 Mon Sep 17 00:00:00 2001
From: Jay Edgar <jkedgar@meta.com>
Date: Thu, 19 Sep 2024 14:12:42 -0700
Subject: [PATCH] Temporary fix for TAO

Summary: I'm investigating a TAO crash and while I'm not yet sure of the root cause, I know where it is crashing.  Add some checks in the code to prevent the crash from occurring to see if TAO can make progress while waiting for the root cause fix.

Differential Revision: D63038824

fbshipit-source-id: d01e733f152ccbf19f14055295d9a920e3a112ee
---
 .../mysql_protocol/MysqlResult.cpp            | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/third-party/squangle/src/squangle/mysql_client/mysql_protocol/MysqlResult.cpp b/third-party/squangle/src/squangle/mysql_client/mysql_protocol/MysqlResult.cpp
index 45cb8331dfc3b..0039f4753fee9 100644
--- a/third-party/squangle/src/squangle/mysql_client/mysql_protocol/MysqlResult.cpp
+++ b/third-party/squangle/src/squangle/mysql_client/mysql_protocol/MysqlResult.cpp
@@ -16,6 +16,10 @@ namespace facebook::common::mysql_client::mysql_protocol {
 class MysqlRowMetadata;
 
 size_t MysqlResult::numFields() const {
+  // T202181457
+  if (!res_) {
+    return 0;
+  }
   auto ret = mysql_num_fields(res_.get());
   VLOG(4) << fmt::format(
       "mysql_num_fields({}) returned {}", (void*)res_.get(), ret);
@@ -23,6 +27,10 @@ size_t MysqlResult::numFields() const {
 }
 
 MYSQL_FIELD* MysqlResult::fields() const {
+  // T202181457
+  if (!res_) {
+    return nullptr;
+  }
   auto ret = mysql_fetch_fields(res_.get());
   VLOG(4) << fmt::format(
       "mysql_fetch_fields({}) returned {}", (void*)res_.get(), (void*)ret);
@@ -30,6 +38,10 @@ MYSQL_FIELD* MysqlResult::fields() const {
 }
 
 size_t MysqlResult::numRows() const {
+  // T202181457
+  if (!res_) {
+    return 0;
+  }
   auto ret = mysql_num_rows(res_.get());
   VLOG(4) << fmt::format(
       "mysql_num_rows({}) returned {}", (void*)res_.get(), ret);
@@ -64,6 +76,8 @@ InternalResult::FetchRowRet MysqlRowFactory(
 } // namespace
 
 InternalResult::FetchRowRet SyncMysqlResult::fetchRow() {
+  // T202181457
+  CHECK(res_);
   auto mysqlRow = mysql_fetch_row(res_.get());
   VLOG(4) << fmt::format(
       "mysql_fetch_row({}) returned {}", (void*)res_.get(), (void*)mysqlRow);
@@ -74,6 +88,12 @@ InternalResult::FetchRowRet SyncMysqlResult::fetchRow() {
 InternalResult::FetchRowRet AsyncMysqlResult::fetchRow() {
   std::unique_ptr<InternalRow> row;
 
+  // T202181457
+  if (!res_) {
+    return std::make_pair(
+        MysqlConnection::toHandlerStatus(NET_ASYNC_ERROR), std::move(row));
+  }
+
   MYSQL_ROW mysqlRow;
   auto ret = mysql_fetch_row_nonblocking(res_.get(), &mysqlRow);
   VLOG(4) << fmt::format(