From 932a70e1f170e6bb7c76dc6e241920e021600229 Mon Sep 17 00:00:00 2001
From: Ilya Bogdanov <ilya.bogdanov@xdev.re>
Date: Sat, 7 Sep 2019 16:26:40 +0300
Subject: [PATCH] Add `DB::latest_sequence_number` method. (#326)

---
 CHANGELOG.md     |  1 +
 src/db.rs        |  5 +++++
 tests/test_db.rs | 11 +++++++++++
 3 files changed, 17 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index de46e50..85e2c0a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@
 * Bumped RocksDB to 6.1.2 (lispy)
 * Added `Sync` and `Send` implementations to `Snapshot` (pavel-mukhanov)
 * Added `raw_iterator_cf_opt` to the DB API (rnarubin)
+* Added `DB::latest_sequence_number` method (vitvakatu)
 
 ## 0.12.2 (2019-05-03)
 
diff --git a/src/db.rs b/src/db.rs
index 2fd59c5..6e5959e 100644
--- a/src/db.rs
+++ b/src/db.rs
@@ -1560,6 +1560,11 @@ impl DB {
             Err(e) => Err(e),
         }
     }
+
+    /// The sequence number of the most recent transaction.
+    pub fn latest_sequence_number(&self) -> u64 {
+        unsafe { ffi::rocksdb_get_latest_sequence_number(self.inner) }
+    }
 }
 
 impl WriteBatch {
diff --git a/tests/test_db.rs b/tests/test_db.rs
index 4240d96..a2da749 100644
--- a/tests/test_db.rs
+++ b/tests/test_db.rs
@@ -240,3 +240,14 @@ fn set_option_test() {
         db.set_options(&multiple_options).unwrap();
     }
 }
+
+#[test]
+fn test_sequence_number() {
+    let path = DBPath::new("_rust_rocksdb_test_sequence_number");
+    {
+        let db = DB::open_default(&path).unwrap();
+        assert_eq!(db.latest_sequence_number(), 0);
+        db.put(b"key", b"value");
+        assert_eq!(db.latest_sequence_number(), 1);
+    }
+}