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Make sure WAL is synced for DB::Write() if write batch is empty

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Summary: This patch makes it a contract that if an empty write batch is passed to DB::Write() and WriteOptions.sync = true, fsync is called to WAL.

Test Plan: A new unit test

Reviewers: ljin, rven, yhchiang, igor

Reviewed By: igor

Subscribers: dhruba, MarkCallaghan, leveldb

Differential Revision: https://reviews.facebook.net/D28365
This commit is contained in:
sdong 2014-11-05 18:07:22 -08:00
parent ea18b944a7
commit ac95ae1b5d
2 changed files with 23 additions and 0 deletions
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21
db/db_test.cc
View File

@ -1270,6 +1270,27 @@ TEST(DBTest, Empty) {
} while (ChangeOptions());
}
TEST(DBTest, WriteEmptyBatch) {
Options options;
options.env = env_;
options.write_buffer_size = 100000;
options = CurrentOptions(options);
CreateAndReopenWithCF({"pikachu"}, options);
ASSERT_OK(Put(1, "foo", "bar"));
env_->sync_counter_.store(0);
WriteOptions wo;
wo.sync = true;
wo.disableWAL = false;
WriteBatch empty_batch;
ASSERT_OK(dbfull()->Write(wo, &empty_batch));
ASSERT_GE(env_->sync_counter_.load(), 1);
// make sure we can re-open it.
ASSERT_OK(TryReopenWithColumnFamilies({"default", "pikachu"}, options));
ASSERT_EQ("bar", Get(1, "foo"));
}
TEST(DBTest, ReadOnlyDB) {
ASSERT_OK(Put("foo", "v1"));
ASSERT_OK(Put("bar", "v2"));

2
include/rocksdb/db.h
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@ -195,6 +195,8 @@ class DB {
}
// Apply the specified updates to the database.
// If `updates` contains no update, WAL will still be synced if
// options.sync=true.
// Returns OK on success, non-OK on failure.
// Note: consider setting options.sync = true.
virtual Status Write(const WriteOptions& options, WriteBatch* updates) = 0;