Configure direct I/O statically in db_stress

Summary:
Previously `db_stress` attempted to configure direct I/O dynamically in `SetOptions()` which had multiple problems (ummm must've never been tested):

- It's a DB option so SetDBOptions should've been called instead
- It's not a dynamic option so even SetDBOptions would fail
- It required enabling SyncPoint to mask O_DIRECT since it had no way to detect whether the DB directory was in tmpfs or not. This required locking that consumed ~80% of db_stress CPU.

In this PR I delete the broken dynamic config and instead configure it statically, only enabling it if the DB directory truly supports O_DIRECT.
Closes https://github.com/facebook/rocksdb/pull/3939

Differential Revision: D8238120

Pulled By: ajkr

fbshipit-source-id: 60bb2deebe6c9b54a3f788079261715b4a229279

tools/db_crashtest.py

@@ -43,6 +43,8 @@ default_params = {
     "subcompactions": lambda: random.randint(1, 4),
     "target_file_size_base": 2097152,
     "target_file_size_multiplier": 2,
+    "use_direct_reads": lambda: random.randint(0, 1),
+    "use_direct_io_for_flush_and_compaction": lambda: random.randint(0, 1),
     "use_full_merge_v1": lambda: random.randint(0, 1),
     "use_merge": lambda: random.randint(0, 1),
     "verify_checksum": 1,
@@ -58,8 +60,19 @@ def get_dbname(test_name):
     else:
         dbname = test_tmpdir + "/rocksdb_crashtest_" + test_name
         shutil.rmtree(dbname, True)
+        os.mkdir(dbname)
     return dbname
 
+
+def is_direct_io_supported(dbname):
+    with tempfile.NamedTemporaryFile(dir=dbname) as f:
+        try:
+            os.open(f.name, os.O_DIRECT)
+        except:
+            return False
+        return True
+
+
 blackbox_default_params = {
     # total time for this script to test db_stress
     "duration": 6000,
@@ -107,6 +120,10 @@ def finalize_and_sanitize(src_params):
                         for (k, v) in src_params.items()])
     if dest_params.get("allow_concurrent_memtable_write", 1) == 1:
         dest_params["memtablerep"] = "skip_list"
+    if dest_params["mmap_read"] == 1 or not is_direct_io_supported(
+            dest_params["db"]):
+        dest_params["use_direct_io_for_flush_and_compaction"] = 0
+        dest_params["use_direct_reads"] = 0
     return dest_params
 
 

tools/db_stress.cc

@@ -1397,8 +1397,6 @@ class StressTest {
              ToString(options_.max_bytes_for_level_multiplier), "1", "2",
          }},
         {"max_sequential_skip_in_iterations", {"4", "8", "12"}},
-        {"use_direct_reads", {"false", "true"}},
-        {"use_direct_io_for_flush_and_compaction", {"false", "true"}},
     };
 
     options_table_ = std::move(options_tbl);
@@ -2837,20 +2835,6 @@ int main(int argc, char** argv) {
   SetUsageMessage(std::string("\nUSAGE:\n") + std::string(argv[0]) +
                   " [OPTIONS]...");
   ParseCommandLineFlags(&argc, &argv, true);
-#if !defined(NDEBUG) && !defined(OS_MACOSX) && !defined(OS_WIN) && \
-  !defined(OS_SOLARIS) && !defined(OS_AIX)
-  rocksdb::SyncPoint::GetInstance()->SetCallBack(
-      "NewWritableFile:O_DIRECT", [&](void* arg) {
-        int* val = static_cast<int*>(arg);
-        *val &= ~O_DIRECT;
-      });
-  rocksdb::SyncPoint::GetInstance()->SetCallBack(
-      "NewRandomAccessFile:O_DIRECT", [&](void* arg) {
-        int* val = static_cast<int*>(arg);
-        *val &= ~O_DIRECT;
-      });
-  rocksdb::SyncPoint::GetInstance()->EnableProcessing();
-#endif
 
   if (FLAGS_statistics) {
     dbstats = rocksdb::CreateDBStatistics();