exercise WAL recycling in crash test (#5070)

Summary:
Since this feature affects the WAL behavior, it seems important our crash-recovery tests cover it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5070

Differential Revision: D14470085

Pulled By: miasantreble

fbshipit-source-id: 9b9682a718a926d57d055e0a5ec867efbd2eb9c1

tools/db_crashtest.py

@@ -48,6 +48,7 @@ default_params = {
     "prefixpercent": 5,
     "progress_reports": 0,
     "readpercent": 45,
+    "recycle_log_file_num": lambda: random.randint(0, 1),
     "reopen": 20,
     "snapshot_hold_ops": 100000,
     "subcompactions": lambda: random.randint(1, 4),

tools/db_stress.cc

@@ -379,6 +379,9 @@ extern std::vector<std::string> rocksdb_kill_prefix_blacklist;
 
 DEFINE_bool(disable_wal, false, "If true, do not write WAL for write.");
 
+DEFINE_uint64(recycle_log_file_num, rocksdb::Options().recycle_log_file_num,
+              "Number of old WAL files to keep around for later recycling");
+
 DEFINE_int64(target_file_size_base, rocksdb::Options().target_file_size_base,
              "Target level-1 file size for compaction");
 
@@ -2605,6 +2608,8 @@ class StressTest {
       options_.use_direct_reads = FLAGS_use_direct_reads;
       options_.use_direct_io_for_flush_and_compaction =
           FLAGS_use_direct_io_for_flush_and_compaction;
+      options_.recycle_log_file_num =
+          static_cast<size_t>(FLAGS_recycle_log_file_num);
       options_.target_file_size_base = FLAGS_target_file_size_base;
       options_.target_file_size_multiplier = FLAGS_target_file_size_multiplier;
       options_.max_bytes_for_level_base = FLAGS_max_bytes_for_level_base;