Remove GetSortedWalFiles/GetCurrentWalFile from the crash test (#6491)

Summary:
Currently, `db_stress` tests a randomly picked one of `GetLiveFiles`,
`GetSortedWalFiles`, and `GetCurrentWalFile` with a 1/N chance when the
command line parameter `get_live_files_and_wal_files_one_in` is specified.
The problem is that `GetSortedWalFiles` and `GetCurrentWalFile` are unreliable
in the sense that they can return errors if another thread removes a WAL file
while they are executing (which is a perfectly plausible and legitimate scenario).
The patch splits this command line parameter into three (one for each API),
and changes the crash test script so that only `GetLiveFiles` is tested during
our continuous crash test runs.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6491

Test Plan:
```
make check
python tools/db_crashtest.py whitebox
```

Reviewed By: siying

Differential Revision: D20312200

Pulled By: ltamasi

fbshipit-source-id: e7c3481eddfe3bd3d5349476e34abc9eee5b7dc8

db_stress_tool/db_stress_common.h

@@ -128,7 +128,9 @@ DECLARE_int32(universal_min_merge_width);
 DECLARE_int32(universal_max_merge_width);
 DECLARE_int32(universal_max_size_amplification_percent);
 DECLARE_int32(clear_column_family_one_in);
-DECLARE_int32(get_live_files_and_wal_files_one_in);
+DECLARE_int32(get_live_files_one_in);
+DECLARE_int32(get_sorted_wal_files_one_in);
+DECLARE_int32(get_current_wal_file_one_in);
 DECLARE_int32(set_options_one_in);
 DECLARE_int32(set_in_place_one_in);
 DECLARE_int64(cache_size);

db_stress_tool/db_stress_gflags.cc

@@ -256,10 +256,21 @@ DEFINE_int32(clear_column_family_one_in, 1000000,
              "it again. If N == 0, never drop/create column families. "
              "When test_batches_snapshots is true, this flag has no effect");
 
-DEFINE_int32(get_live_files_and_wal_files_one_in, 1000000,
-             "With a chance of 1/N, call GetLiveFiles, GetSortedWalFiles "
-             "and GetCurrentWalFile to verify if it returns correctly. If "
-             "N == 0, never call the three interfaces.");
+DEFINE_int32(get_live_files_one_in, 1000000,
+             "With a chance of 1/N, call GetLiveFiles to verify if it returns "
+             "correctly. If N == 0, do not call the interface.");
+
+DEFINE_int32(
+    get_sorted_wal_files_one_in, 1000000,
+    "With a chance of 1/N, call GetSortedWalFiles to verify if it returns "
+    "correctly. (Note that this API may legitimately return an error.) If N == "
+    "0, do not call the interface.");
+
+DEFINE_int32(
+    get_current_wal_file_one_in, 1000000,
+    "With a chance of 1/N, call GetCurrentWalFile to verify if it returns "
+    "correctly. (Note that this API may legitimately return an error.) If N == "
+    "0, do not call the interface.");
 
 DEFINE_int32(set_options_one_in, 0,
              "With a chance of 1/N, change some random options");

db_stress_tool/db_stress_test_base.cc

@@ -593,13 +593,28 @@ void StressTest::OperateDb(ThreadState* thread) {
       }
 
 #ifndef ROCKSDB_LITE
-      // Every 1 in N verify the one of the following: 1) GetLiveFiles
-      // 2) GetSortedWalFiles 3) GetCurrentWalFile. Each time, randomly select
-      // one of them to run the test.
-      if (thread->rand.OneInOpt(FLAGS_get_live_files_and_wal_files_one_in)) {
-        Status status = VerifyGetLiveAndWalFiles(thread);
+      // Verify GetLiveFiles with a 1 in N chance.
+      if (thread->rand.OneInOpt(FLAGS_get_live_files_one_in)) {
+        Status status = VerifyGetLiveFiles();
         if (!status.ok()) {
-          VerificationAbort(shared, "VerifyGetLiveAndWalFiles status not OK",
+          VerificationAbort(shared, "VerifyGetLiveFiles status not OK", status);
+        }
+      }
+
+      // Verify GetSortedWalFiles with a 1 in N chance.
+      if (thread->rand.OneInOpt(FLAGS_get_sorted_wal_files_one_in)) {
+        Status status = VerifyGetSortedWalFiles();
+        if (!status.ok()) {
+          VerificationAbort(shared, "VerifyGetSortedWalFiles status not OK",
+                            status);
+        }
+      }
+
+      // Verify GetCurrentWalFile with a 1 in N chance.
+      if (thread->rand.OneInOpt(FLAGS_get_current_wal_file_one_in)) {
+        Status status = VerifyGetCurrentWalFile();
+        if (!status.ok()) {
+          VerificationAbort(shared, "VerifyGetCurrentWalFile status not OK",
                             status);
         }
       }
@@ -978,29 +993,24 @@ Status StressTest::TestIterate(ThreadState* thread,
 }
 
 #ifndef ROCKSDB_LITE
-// Test the return status of GetLiveFiles, GetSortedWalFiles, and
-// GetCurrentWalFile. Each time, randomly select one of them to run
-// and return the status.
-Status StressTest::VerifyGetLiveAndWalFiles(ThreadState* thread) {
-  int case_num = thread->rand.Uniform(3);
-  if (case_num == 0) {
+// Test the return status of GetLiveFiles.
+Status StressTest::VerifyGetLiveFiles() const {
   std::vector<std::string> live_file;
-    uint64_t manifest_size;
+  uint64_t manifest_size = 0;
   return db_->GetLiveFiles(live_file, &manifest_size);
 }
 
-  if (case_num == 1) {
+// Test the return status of GetSortedWalFiles.
+Status StressTest::VerifyGetSortedWalFiles() const {
   VectorLogPtr log_ptr;
   return db_->GetSortedWalFiles(log_ptr);
 }
 
-  if (case_num == 2) {
+// Test the return status of GetCurrentWalFile.
+Status StressTest::VerifyGetCurrentWalFile() const {
   std::unique_ptr<LogFile> cur_wal_file;
   return db_->GetCurrentWalFile(&cur_wal_file);
 }
-  assert(false);
-  return Status::Corruption("Undefined case happens!");
-}
 #endif  // !ROCKSDB_LITE
 
 // Compare the two iterator, iter and cmp_iter are in the same position,

db_stress_tool/db_stress_test_base.h

@@ -184,7 +184,10 @@ class StressTest {
 
   Status MaybeReleaseSnapshots(ThreadState* thread, uint64_t i);
 #ifndef ROCKSDB_LITE
-  Status VerifyGetLiveAndWalFiles(ThreadState* thread);
+  Status VerifyGetLiveFiles() const;
+  Status VerifyGetSortedWalFiles() const;
+  Status VerifyGetCurrentWalFile() const;
+
   virtual Status TestApproximateSize(
       ThreadState* thread, uint64_t iteration,
       const std::vector<int>& rand_column_families,

tools/db_crashtest.py

@@ -51,7 +51,11 @@ default_params = {
     "enable_pipelined_write": lambda: random.randint(0, 1),
     "expected_values_path": expected_values_file.name,
     "flush_one_in": 1000000,
-    "get_live_files_and_wal_files_one_in": 1000000,
+    "get_live_files_one_in": 1000000,
+    # Note: the following two are intentionally disabled as the corresponding
+    # APIs are not guaranteed to succeed.
+    "get_sorted_wal_files_one_in": 0,
+    "get_current_wal_file_one_in": 0,
     # Temporarily disable hash index
     "index_type": lambda: random.choice([0,2]),
     "max_background_compactions": 20,