Configure breakpad test to log synchronously

Otherwise at exit some log entries can be lost resulting in an
intermittent test failure.

1/1 Test #4: memcached-breakpad-test-std_exception_via_std_thread ...***Failed    0.08 sec
2024-01-19T10:19:11 INFO Spawning memcached
2024-01-19T10:19:11 INFO Process exited with status -6
2024-01-19T10:19:11 ERROR FAIL - No exception what() message written to stderr on crash.
=== stderr begin ===
libc++abi: terminating due to uncaught exception of type std::runtime_error: crash_engine: This exception wasn't handled
=== stderr end ===

Change-Id: Iaa679d1bb7a4593715f5beab004fd612809cb7fa
Reviewed-on: https://review.couchbase.org/c/kv_engine/+/204112
Tested-by: Pavlos Georgiou <[email protected]>
Reviewed-by: Trond Norbye <[email protected]>

Author: pavlosg

tests/breakpad_test.py

@@ -273,7 +273,8 @@ def set_core_file_ulimit():
           "root" : os.path.abspath(args.source_root),
           "verbosity" : 2,
           "rbac_file" : os.path.abspath(rbac_file.name),
-          "logger" : { "filename" : test_temp_dir + "/log"}}
+          "logger" : { "filename" : test_temp_dir + "/log",
+                       "unit_test" : True }}
 config_json = json.dumps(config)
 
 # Need a temporary file which can be opened (a second time) by memcached,

utilities/terminate_handler.cc

@@ -32,10 +32,10 @@ static void log_handled_exception() {
 #endif
     // Attempt to get the exception's what() message.
     try {
-        static int tried_throw = 0;
+        static std::atomic_bool tried_throw = false;
         // try once to re-throw currently active exception (so we can print
         // its what() message).
-        if (tried_throw++ == 0) {
+        if (!tried_throw.exchange(true)) {
             throw;
         }
     } catch (const std::exception& e) {