Enable unsynced data loss in crash test (facebook#9947)

Summary:
`db_stress` already tracks expected state history to verify prefix-recoverability when `sync_fault_injection` is enabled. This PR enables `sync_fault_injection` in `db_crashtest.py`.

Previously enabling `sync_fault_injection` would cause whole unsynced files to be dropped. This PR adds a more interesting case of losing only the tail of unsynced data by implementing `TestFSWritableFile::RangeSync()` and enabling `{wal_,}bytes_per_sync`.

Pull Request resolved: facebook#9947

Test Plan:
- regular blackbox, blackbox --simple
- various commands to stress this new case, such as `TEST_TMPDIR=/dev/shm python3 tools/db_crashtest.py blackbox --max_key=100000 --write_buffer_size=2097152 --avoid_flush_during_recovery=1 --disable_wal=0 --interval=10 --db_write_buffer_size=0 --sync_fault_injection=1 --wal_compression=none --delpercent=0 --delrangepercent=0 --prefixpercent=0 --iterpercent=0 --writepercent=100 --readpercent=0 --wal_bytes_per_sync=131072 --duration=36000 --sync=0 --open_write_fault_one_in=16`

Reviewed By: riversand963

Differential Revision: D36152775

Pulled By: ajkr

fbshipit-source-id: 44b68a7fad0a4cf74af9fe1f39be01baab8141d8

db_stress_tool/db_stress_common.h

@@ -166,6 +166,8 @@ DECLARE_bool(mock_direct_io);
 DECLARE_bool(statistics);
 DECLARE_bool(sync);
 DECLARE_bool(use_fsync);
+DECLARE_uint64(bytes_per_sync);
+DECLARE_uint64(wal_bytes_per_sync);
 DECLARE_int32(kill_random_test);
 DECLARE_string(kill_exclude_prefixes);
 DECLARE_bool(disable_wal);

db_stress_tool/db_stress_gflags.cc

@@ -516,6 +516,15 @@ DEFINE_bool(sync, false, "Sync all writes to disk");
 
 DEFINE_bool(use_fsync, false, "If true, issue fsync instead of fdatasync");
 
+DEFINE_uint64(bytes_per_sync, ROCKSDB_NAMESPACE::Options().bytes_per_sync,
+              "If nonzero, sync SST file data incrementally after every "
+              "`bytes_per_sync` bytes are written");
+
+DEFINE_uint64(wal_bytes_per_sync,
+              ROCKSDB_NAMESPACE::Options().wal_bytes_per_sync,
+              "If nonzero, sync WAL file data incrementally after every "
+              "`bytes_per_sync` bytes are written");
+
 DEFINE_int32(kill_random_test, 0,
              "If non-zero, kill at various points in source code with "
              "probability 1/this");

db_stress_tool/db_stress_test_base.cc

@@ -2368,6 +2368,8 @@ void StressTest::Open(SharedState* shared) {
     options_.statistics = dbstats;
     options_.env = db_stress_env;
     options_.use_fsync = FLAGS_use_fsync;
+    options_.bytes_per_sync = FLAGS_bytes_per_sync;
+    options_.wal_bytes_per_sync = FLAGS_wal_bytes_per_sync;
     options_.compaction_readahead_size = FLAGS_compaction_readahead_size;
     options_.allow_mmap_reads = FLAGS_mmap_read;
     options_.allow_mmap_writes = FLAGS_mmap_write;

tools/db_crashtest.py

@@ -132,6 +132,8 @@
     # Sync mode might make test runs slower so running it in a smaller chance
     "sync" : lambda : random.choice(
         [1 if t == 0 else 0 for t in range(0, 20)]),
+    "bytes_per_sync": lambda: random.choice([0, 262144]),
+    "wal_bytes_per_sync": lambda: random.choice([0, 524288]),
     # Disable compaction_readahead_size because the test is not passing.
     #"compaction_readahead_size" : lambda : random.choice(
     #    [0, 0, 1024 * 1024]),
@@ -153,7 +155,7 @@
     "open_metadata_write_fault_one_in": lambda: random.choice([0, 0, 8]),
     "open_write_fault_one_in": lambda: random.choice([0, 0, 16]),
     "open_read_fault_one_in": lambda: random.choice([0, 0, 32]),
-    "sync_fault_injection": False,
+    "sync_fault_injection": lambda: random.randint(0, 1),
     "get_property_one_in": 1000000,
     "paranoid_file_checks": lambda: random.choice([0, 1, 1, 1]),
     "max_write_buffer_size_to_maintain": lambda: random.choice(

utilities/fault_injection_fs.cc

@@ -16,6 +16,7 @@
 
 #include "utilities/fault_injection_fs.h"
 
+#include <algorithm>
 #include <functional>
 #include <utility>
 
@@ -290,6 +291,33 @@ IOStatus TestFSWritableFile::Sync(const IOOptions& options,
   return io_s;
 }
 
+IOStatus TestFSWritableFile::RangeSync(uint64_t offset, uint64_t nbytes,
+                                       const IOOptions& options,
+                                       IODebugContext* dbg) {
+  if (!fs_->IsFilesystemActive()) {
+    return fs_->GetError();
+  }
+  // Assumes caller passes consecutive byte ranges.
+  uint64_t sync_limit = offset + nbytes;
+  uint64_t buf_begin =
+      state_.pos_at_last_sync_ < 0 ? 0 : state_.pos_at_last_sync_;
+
+  IOStatus io_s;
+  if (sync_limit < buf_begin) {
+    return io_s;
+  }
+  uint64_t num_to_sync = std::min(static_cast<uint64_t>(state_.buffer_.size()),
+                                  sync_limit - buf_begin);
+  Slice buf_to_sync(state_.buffer_.data(), num_to_sync);
+  io_s = target_->Append(buf_to_sync, options, dbg);
+  state_.buffer_ = state_.buffer_.substr(num_to_sync);
+  // Ignore sync errors
+  target_->RangeSync(offset, nbytes, options, dbg).PermitUncheckedError();
+  state_.pos_at_last_sync_ = offset + num_to_sync;
+  fs_->WritableFileSynced(state_);
+  return io_s;
+}
+
 TestFSRandomRWFile::TestFSRandomRWFile(const std::string& /*fname*/,
                                        std::unique_ptr<FSRandomRWFile>&& f,
                                        FaultInjectionTestFS* fs)

utilities/fault_injection_fs.h

@@ -76,6 +76,9 @@ class TestFSWritableFile : public FSWritableFile {
                          IODebugContext* dbg) override;
   virtual IOStatus Flush(const IOOptions&, IODebugContext*) override;
   virtual IOStatus Sync(const IOOptions& options, IODebugContext* dbg) override;
+  virtual IOStatus RangeSync(uint64_t /*offset*/, uint64_t /*nbytes*/,
+                             const IOOptions& options,
+                             IODebugContext* dbg) override;
   virtual bool IsSyncThreadSafe() const override { return true; }
   virtual IOStatus PositionedAppend(const Slice& data, uint64_t offset,
                                     const IOOptions& options,