Avoid overwriting OPTIONS file settings in db_bench (#9862)

Summary:
`InitializeOptionsGeneral()` was overwriting many options that were already configured by OPTIONS file, potentially with the flag default values. This PR changes that function to only overwrite options in limited scenarios, as described at the top of its definition. Block cache is still a violation.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9862

Test Plan: ran under various scenarios (multi-DB, single DB, OPTIONS file, flags) and verified options are set as expected

Reviewed By: jay-zhuang

Differential Revision: D35736960

Pulled By: ajkr

fbshipit-source-id: 75b77740af37e6f5741618f8a8f5685df2417d03

tools/db_bench_tool.cc

@@ -3857,6 +3857,26 @@ class Benchmark {
     assert(db_.db == nullptr);
 
     options.env = FLAGS_env;
+    options.wal_dir = FLAGS_wal_dir;
+    options.dump_malloc_stats = FLAGS_dump_malloc_stats;
+    options.stats_dump_period_sec =
+        static_cast<unsigned int>(FLAGS_stats_dump_period_sec);
+    options.stats_persist_period_sec =
+        static_cast<unsigned int>(FLAGS_stats_persist_period_sec);
+    options.persist_stats_to_disk = FLAGS_persist_stats_to_disk;
+    options.stats_history_buffer_size =
+        static_cast<size_t>(FLAGS_stats_history_buffer_size);
+    options.avoid_flush_during_recovery = FLAGS_avoid_flush_during_recovery;
+
+    options.compression_opts.level = FLAGS_compression_level;
+    options.compression_opts.max_dict_bytes = FLAGS_compression_max_dict_bytes;
+    options.compression_opts.zstd_max_train_bytes =
+        FLAGS_compression_zstd_max_train_bytes;
+    options.compression_opts.parallel_threads =
+        FLAGS_compression_parallel_threads;
+    options.compression_opts.max_dict_buffer_bytes =
+        FLAGS_compression_max_dict_buffer_bytes;
+
     options.max_open_files = FLAGS_open_files;
     if (FLAGS_cost_write_buffer_to_cache || FLAGS_db_write_buffer_size != 0) {
       options.write_buffer_manager.reset(
@@ -4285,37 +4305,34 @@ class Benchmark {
   }
 
   void InitializeOptionsGeneral(Options* opts) {
+    // Be careful about what is set here to avoid accidentally overwriting
+    // settings already configured by OPTIONS file. Only configure settings that
+    // are needed for the benchmark to run, settings for shared objects that
+    // were not configured already, settings that require dynamically invoking
+    // APIs, and settings for the benchmark itself.
     Options& options = *opts;
 
-    options.create_missing_column_families = FLAGS_num_column_families > 1;
+    // Always set these since they are harmless when not needed and prevent
+    // a guaranteed failure when they are needed.
+    options.create_missing_column_families = true;
+    options.create_if_missing = true;
+
+    if (options.statistics == nullptr) {
       options.statistics = dbstats;
-    options.wal_dir = FLAGS_wal_dir;
-    options.create_if_missing = !FLAGS_use_existing_db;
-    options.dump_malloc_stats = FLAGS_dump_malloc_stats;
-    options.stats_dump_period_sec =
-        static_cast<unsigned int>(FLAGS_stats_dump_period_sec);
-    options.stats_persist_period_sec =
-        static_cast<unsigned int>(FLAGS_stats_persist_period_sec);
-    options.persist_stats_to_disk = FLAGS_persist_stats_to_disk;
-    options.stats_history_buffer_size =
-        static_cast<size_t>(FLAGS_stats_history_buffer_size);
-    options.avoid_flush_during_recovery = FLAGS_avoid_flush_during_recovery;
+    }
 
-    options.compression_opts.level = FLAGS_compression_level;
-    options.compression_opts.max_dict_bytes = FLAGS_compression_max_dict_bytes;
-    options.compression_opts.zstd_max_train_bytes =
-        FLAGS_compression_zstd_max_train_bytes;
-    options.compression_opts.parallel_threads =
-        FLAGS_compression_parallel_threads;
-    options.compression_opts.max_dict_buffer_bytes =
-        FLAGS_compression_max_dict_buffer_bytes;
-    // If this is a block based table, set some related options
     auto table_options =
         options.table_factory->GetOptions<BlockBasedTableOptions>();
     if (table_options != nullptr) {
-      if (FLAGS_cache_size) {
+      if (FLAGS_cache_size > 0) {
+        // This violates this function's rules on when to set options. But we
+        // have to do it because the case of unconfigured block cache in OPTIONS
+        // file is indistinguishable (it is sanitized to 8MB by this point, not
+        // nullptr), and our regression tests assume this will be the shared
+        // block cache, even with OPTIONS file provided.
         table_options->block_cache = cache_;
       }
+      if (table_options->filter_policy == nullptr) {
         if (FLAGS_bloom_bits < 0) {
           table_options->filter_policy = BlockBasedTableOptions().filter_policy;
         } else if (FLAGS_bloom_bits == 0) {
@@ -4328,7 +4345,8 @@ class Benchmark {
                   ROCKSDB_NAMESPACE::ToString(FLAGS_bloom_bits),
               &table_options->filter_policy);
           if (!s.ok()) {
-          fprintf(stderr, "failure creating obsolete block-based filter: %s\n",
+            fprintf(stderr,
+                    "failure creating obsolete block-based filter: %s\n",
                     s.ToString().c_str());
             exit(1);
           }
@@ -4338,6 +4356,9 @@ class Benchmark {
                                       : NewBloomFilterPolicy(FLAGS_bloom_bits));
         }
       }
+    }
+
+    if (options.row_cache == nullptr) {
       if (FLAGS_row_cache_size) {
         if (FLAGS_cache_numshardbits >= 1) {
           options.row_cache =
@@ -4346,34 +4367,43 @@ class Benchmark {
           options.row_cache = NewLRUCache(FLAGS_row_cache_size);
         }
       }
+    }
+
+    if (options.env == Env::Default()) {
+      options.env = FLAGS_env;
+    }
     if (FLAGS_enable_io_prio) {
-      FLAGS_env->LowerThreadPoolIOPriority(Env::LOW);
-      FLAGS_env->LowerThreadPoolIOPriority(Env::HIGH);
+      options.env->LowerThreadPoolIOPriority(Env::LOW);
+      options.env->LowerThreadPoolIOPriority(Env::HIGH);
     }
     if (FLAGS_enable_cpu_prio) {
-      FLAGS_env->LowerThreadPoolCPUPriority(Env::LOW);
-      FLAGS_env->LowerThreadPoolCPUPriority(Env::HIGH);
+      options.env->LowerThreadPoolCPUPriority(Env::LOW);
+      options.env->LowerThreadPoolCPUPriority(Env::HIGH);
     }
-    options.env = FLAGS_env;
+
     if (FLAGS_sine_write_rate) {
       FLAGS_benchmark_write_rate_limit = static_cast<uint64_t>(SineRate(0));
     }
 
+    if (options.rate_limiter == nullptr) {
       if (FLAGS_rate_limiter_bytes_per_sec > 0) {
         options.rate_limiter.reset(NewGenericRateLimiter(
-          FLAGS_rate_limiter_bytes_per_sec, FLAGS_rate_limiter_refill_period_us,
-          10 /* fairness */,
+            FLAGS_rate_limiter_bytes_per_sec,
+            FLAGS_rate_limiter_refill_period_us, 10 /* fairness */,
             FLAGS_rate_limit_bg_reads ? RateLimiter::Mode::kReadsOnly
                                       : RateLimiter::Mode::kWritesOnly,
             FLAGS_rate_limiter_auto_tuned));
       }
+    }
 
     options.listeners.emplace_back(listener_);
 
+    if (options.file_checksum_gen_factory == nullptr) {
       if (FLAGS_file_checksum) {
         options.file_checksum_gen_factory.reset(
             new FileChecksumGenCrc32cFactory());
       }
+    }
 
     if (FLAGS_num_multi_db <= 1) {
       OpenDb(options, FLAGS_db, &db_);
@@ -4391,10 +4421,12 @@ class Benchmark {
     }
 
     // KeepFilter is a noop filter, this can be used to test compaction filter
+    if (options.compaction_filter == nullptr) {
       if (FLAGS_use_keep_filter) {
         options.compaction_filter = new KeepFilter();
         fprintf(stdout, "A noop compaction filter is used\n");
       }
+    }
 
     if (FLAGS_use_existing_keys) {
       // Only work on single database