Get number levels from options (#129)

librocksdb_sys/crocksdb/c.cc

@@ -1943,6 +1943,10 @@ void crocksdb_options_set_num_levels(crocksdb_options_t* opt, int n) {
   opt->rep.num_levels = n;
 }
 
+int crocksdb_options_get_num_levels(crocksdb_options_t *opt) {
+  return opt->rep.num_levels;
+}
+
 void crocksdb_options_set_level0_file_num_compaction_trigger(
     crocksdb_options_t* opt, int n) {
   opt->rep.level0_file_num_compaction_trigger = n;

librocksdb_sys/crocksdb/crocksdb/c.h

@@ -755,6 +755,8 @@ crocksdb_options_set_memtable_insert_with_hint_prefix_extractor(
     crocksdb_options_t*, crocksdb_slicetransform_t*);
 extern C_ROCKSDB_LIBRARY_API void crocksdb_options_set_num_levels(
     crocksdb_options_t*, int);
+extern C_ROCKSDB_LIBRARY_API int crocksdb_options_get_num_levels(
+    crocksdb_options_t*);
 extern C_ROCKSDB_LIBRARY_API void
 crocksdb_options_set_level0_file_num_compaction_trigger(crocksdb_options_t*, int);
 extern C_ROCKSDB_LIBRARY_API void

librocksdb_sys/src/lib.rs

@@ -441,6 +441,7 @@ extern "C" {
     ) -> bool;
     pub fn crocksdb_options_set_stats_dump_period_sec(options: *mut Options, v: usize);
     pub fn crocksdb_options_set_num_levels(options: *mut Options, v: c_int);
+    pub fn crocksdb_options_get_num_levels(options: *mut Options) -> c_int;
     pub fn crocksdb_options_set_db_log_dir(options: *mut Options, path: *const c_char);
     pub fn crocksdb_options_set_wal_dir(options: *mut Options, path: *const c_char);
     pub fn crocksdb_options_set_wal_ttl_seconds(options: *mut Options, ttl: u64);

src/rocksdb_options.rs

@@ -1088,6 +1088,10 @@ impl ColumnFamilyOptions {
         }
     }
 
+    pub fn get_num_levels(&self) -> usize {
+        unsafe { crocksdb_ffi::crocksdb_options_get_num_levels(self.inner) as usize }
+    }
+
     pub fn set_prefix_extractor<S>(
         &mut self,
         name: S,

tests/test_rocksdb_options.rs

@@ -29,6 +29,7 @@ fn test_set_num_levels() {
     let mut cf_opts = ColumnFamilyOptions::new();
     opts.create_if_missing(true);
     cf_opts.set_num_levels(2);
+    assert_eq!(2, cf_opts.get_num_levels());
     let db = DB::open_cf(
         opts,
         path.path().to_str().unwrap(),