Don't leak dropped column families (#509)

src/column_family.rs

@@ -14,6 +14,8 @@
 
 use crate::{db::MultiThreaded, ffi, Options};
 
+use std::sync::Arc;
+
 /// The name of the default column family.
 ///
 /// The column family with this name is created implicitly whenever column
@@ -52,19 +54,62 @@ pub struct ColumnFamily {
 /// single-threaded mode). `Clone`/`Copy` is safe because this lifetime is bound to DB like
 /// iterators/snapshots. On top of it, this is as cheap and small as `&ColumnFamily` because
 /// this only has a single pointer-wide field.
-#[derive(Clone, Copy)]
 pub struct BoundColumnFamily<'a> {
     pub(crate) inner: *mut ffi::rocksdb_column_family_handle_t,
     pub(crate) multi_threaded_cfs: std::marker::PhantomData<&'a MultiThreaded>,
 }
 
+// internal struct which isn't exposed to public api.
+// but its memory will be exposed after transmute()-ing to BoundColumnFamily.
+// ColumnFamily's lifetime should be bound to DB. But, db holds cfs and cfs can't easily
+// self-reference DB as its lifetime due to rust's type system
+pub(crate) struct UnboundColumnFamily {
+    pub(crate) inner: *mut ffi::rocksdb_column_family_handle_t,
+}
+
+impl UnboundColumnFamily {
+    pub(crate) fn bound_column_family<'a>(self: Arc<Self>) -> Arc<BoundColumnFamily<'a>> {
+        // SAFETY: the new BoundColumnFamily here just adding lifetime,
+        // so that column family handle won't outlive db.
+        unsafe { std::mem::transmute(self) }
+    }
+}
+
+fn destroy_handle(handle: *mut ffi::rocksdb_column_family_handle_t) {
+    // SAFETY: This should be called only from various Drop::drop(), strictly keeping a 1-to-1
+    // ownership to avoid double invocation to the rocksdb function with same handle.
+    unsafe {
+        ffi::rocksdb_column_family_handle_destroy(handle);
+    }
+}
+
+impl Drop for ColumnFamily {
+    fn drop(&mut self) {
+        destroy_handle(self.inner);
+    }
+}
+
+// these behaviors must be identical between BoundColumnFamily and UnboundColumnFamily
+// due to the unsafe transmute() in bound_column_family()!
+impl<'a> Drop for BoundColumnFamily<'a> {
+    fn drop(&mut self) {
+        destroy_handle(self.inner);
+    }
+}
+
+impl Drop for UnboundColumnFamily {
+    fn drop(&mut self) {
+        destroy_handle(self.inner);
+    }
+}
+
 /// Handy type alias to hide actual type difference to reference [`ColumnFamily`]
 /// depending on the `multi-threaded-cf` crate feature.
 #[cfg(not(feature = "multi-threaded-cf"))]
 pub type ColumnFamilyRef<'a> = &'a ColumnFamily;
 
 #[cfg(feature = "multi-threaded-cf")]
-pub type ColumnFamilyRef<'a> = BoundColumnFamily<'a>;
+pub type ColumnFamilyRef<'a> = Arc<BoundColumnFamily<'a>>;
 
 /// Utility trait to accept both supported references to `ColumnFamily`
 /// (`&ColumnFamily` and `BoundColumnFamily`)
@@ -72,13 +117,24 @@ pub trait AsColumnFamilyRef {
     fn inner(&self) -> *mut ffi::rocksdb_column_family_handle_t;
 }
 
+impl AsColumnFamilyRef for ColumnFamily {
+    fn inner(&self) -> *mut ffi::rocksdb_column_family_handle_t {
+        self.inner
+    }
+}
+
 impl<'a> AsColumnFamilyRef for &'a ColumnFamily {
     fn inner(&self) -> *mut ffi::rocksdb_column_family_handle_t {
         self.inner
     }
 }
 
-impl<'a> AsColumnFamilyRef for BoundColumnFamily<'a> {
+// Only implement for Arc-ed BoundColumnFamily as this tightly coupled and
+// implmetation detail, considering use of std::mem::transmute. BoundColumnFamily
+// isn't expected to be used as naked.
+// Also, ColumnFamilyRef might not be Arc<BoundColumnFamily<'a>> depending crate
+// feature flags so, we can't use the type alias here.
+impl<'a> AsColumnFamilyRef for Arc<BoundColumnFamily<'a>> {
     fn inner(&self) -> *mut ffi::rocksdb_column_family_handle_t {
         self.inner
     }

src/db.rs

@@ -16,6 +16,7 @@
 use crate::{
     column_family::AsColumnFamilyRef,
     column_family::BoundColumnFamily,
+    column_family::UnboundColumnFamily,
     db_options::OptionsMustOutliveDB,
     ffi,
     ffi_util::{from_cstr, opt_bytes_to_ptr, raw_data, to_cpath},
@@ -31,24 +32,35 @@ use std::ffi::{CStr, CString};
 use std::fmt;
 use std::fs;
 use std::iter;
-use std::marker::PhantomData;
 use std::path::Path;
 use std::path::PathBuf;
 use std::ptr;
 use std::slice;
 use std::str;
+use std::sync::Arc;
 use std::sync::RwLock;
 use std::time::Duration;
 
-// Marker trait to specify single or multi threaded column family alternations for DB
-// Also, this is minimum common API sharable between SingleThreaded and
-// MultiThreaded. Others differ in self mutability and return type.
+/// Marker trait to specify single or multi threaded column family alternations for
+/// [`DBWithThreadMode<T>`]
+///
+/// This arrangement makes differences in self mutability and return type in
+/// some of `DBWithThreadMode` methods.
+///
+/// While being a marker trait to be generic over `DBWithThreadMode`, this trait
+/// also has a minimum set of not-encapsulated internal methods between
+/// [`SingleThreaded`] and [`MultiThreaded`].  These methods aren't expected to be
+/// called and defined externally.
 pub trait ThreadMode {
-    fn new(cf_map: BTreeMap<String, ColumnFamily>) -> Self;
-    fn cf_drop_all(&mut self);
+    /// Internal implementation for storing column family handles
+    fn new_cf_map_internal(
+        cf_map: BTreeMap<String, *mut ffi::rocksdb_column_family_handle_t>,
+    ) -> Self;
+    /// Internal implementation for dropping column family handles
+    fn drop_all_cfs_internal(&mut self);
 }
 
-/// Actual marker type for the internal marker trait `ThreadMode`, which holds
+/// Actual marker type for the marker trait `ThreadMode`, which holds
 /// a collection of column families without synchronization primitive, providing
 /// no overhead for the single-threaded column family alternations. The other
 /// mode is [`MultiThreaded`].
@@ -58,47 +70,56 @@ pub struct SingleThreaded {
     cfs: BTreeMap<String, ColumnFamily>,
 }
 
-/// Actual marker type for the internal marker trait `ThreadMode`, which holds
+/// Actual marker type for the marker trait `ThreadMode`, which holds
 /// a collection of column families wrapped in a RwLock to be mutated
 /// concurrently. The other mode is [`SingleThreaded`].
 ///
 /// See [`DB`] for more details, including performance implications for each mode
 pub struct MultiThreaded {
-    cfs: RwLock<BTreeMap<String, ColumnFamily>>,
+    cfs: RwLock<BTreeMap<String, Arc<UnboundColumnFamily>>>,
 }
 
 impl ThreadMode for SingleThreaded {
-    fn new(cfs: BTreeMap<String, ColumnFamily>) -> Self {
-        Self { cfs }
+    fn new_cf_map_internal(
+        cfs: BTreeMap<String, *mut ffi::rocksdb_column_family_handle_t>,
+    ) -> Self {
+        Self {
+            cfs: cfs
+                .into_iter()
+                .map(|(n, c)| (n, ColumnFamily { inner: c }))
+                .collect(),
+        }
     }
 
-    fn cf_drop_all(&mut self) {
-        for cf in self.cfs.values() {
-            unsafe {
-                ffi::rocksdb_column_family_handle_destroy(cf.inner);
-            }
-        }
+    fn drop_all_cfs_internal(&mut self) {
+        // Cause all ColumnFamily objects to be Drop::drop()-ed.
+        self.cfs.clear();
     }
 }
 
 impl ThreadMode for MultiThreaded {
-    fn new(cfs: BTreeMap<String, ColumnFamily>) -> Self {
+    fn new_cf_map_internal(
+        cfs: BTreeMap<String, *mut ffi::rocksdb_column_family_handle_t>,
+    ) -> Self {
         Self {
-            cfs: RwLock::new(cfs),
+            cfs: RwLock::new(
+                cfs.into_iter()
+                    .map(|(n, c)| (n, Arc::new(UnboundColumnFamily { inner: c })))
+                    .collect(),
+            ),
         }
     }
 
-    fn cf_drop_all(&mut self) {
-        for cf in self.cfs.read().unwrap().values() {
-            unsafe {
-                ffi::rocksdb_column_family_handle_destroy(cf.inner);
-            }
-        }
+    fn drop_all_cfs_internal(&mut self) {
+        // Cause all UnboundColumnFamily objects to be Drop::drop()-ed.
+        self.cfs.write().unwrap().clear();
     }
 }
 
 /// A RocksDB database.
 ///
+/// This is previously named [`DB`], which is a type alias now for compatibility.
+///
 /// See crate level documentation for a simple usage example.
 pub struct DBWithThreadMode<T: ThreadMode> {
     pub(crate) inner: *mut ffi::rocksdb_t,
@@ -120,7 +141,7 @@ pub trait DBAccess {
 
     fn get_cf_opt<K: AsRef<[u8]>>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         key: K,
         readopts: &ReadOptions,
     ) -> Result<Option<Vec<u8>>, Error>;
@@ -141,7 +162,7 @@ impl<T: ThreadMode> DBAccess for DBWithThreadMode<T> {
 
     fn get_cf_opt<K: AsRef<[u8]>>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         key: K,
         readopts: &ReadOptions,
     ) -> Result<Option<Vec<u8>>, Error> {
@@ -154,7 +175,7 @@ impl<T: ThreadMode> DBAccess for DBWithThreadMode<T> {
 ///
 /// # Compatibility and multi-threaded mode
 ///
-/// Previously, `DB` was defined as a direct struct. Now, it's type-aliased for
+/// Previously, [`DB`] was defined as a direct `struct`. Now, it's type-aliased for
 /// compatibility. Use `DBWithThreadMode<MultiThreaded>` for multi-threaded
 /// column family alternations.
 ///
@@ -421,7 +442,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
             }
 
             for (cf_desc, inner) in cfs_v.iter().zip(cfhandles) {
-                cf_map.insert(cf_desc.name.clone(), ColumnFamily { inner });
+                cf_map.insert(cf_desc.name.clone(), inner);
             }
         }
 
@@ -432,7 +453,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
         Ok(Self {
             inner: db,
             path: path.as_ref().to_path_buf(),
-            cfs: T::new(cf_map),
+            cfs: T::new_cf_map_internal(cf_map),
             _outlive: outlive,
         })
     }
@@ -584,7 +605,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
     /// Flushes database memtables to SST files on the disk for a given column family.
     pub fn flush_cf_opt(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         flushopts: &FlushOptions,
     ) -> Result<(), Error> {
         unsafe {
@@ -599,7 +620,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
 
     /// Flushes database memtables to SST files on the disk for a given column family using default
     /// options.
-    pub fn flush_cf(&self, cf: impl AsColumnFamilyRef) -> Result<(), Error> {
+    pub fn flush_cf(&self, cf: &impl AsColumnFamilyRef) -> Result<(), Error> {
         self.flush_cf_opt(cf, &FlushOptions::default())
     }
 
@@ -644,7 +665,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
     /// [`get_pinned_cf_opt`](#method.get_pinned_cf_opt) to avoid unnecessary memory.
     pub fn get_cf_opt<K: AsRef<[u8]>>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         key: K,
         readopts: &ReadOptions,
     ) -> Result<Option<Vec<u8>>, Error> {
@@ -657,7 +678,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
     /// [`get_pinned_cf`](#method.get_pinned_cf) to avoid unnecessary memory.
     pub fn get_cf<K: AsRef<[u8]>>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         key: K,
     ) -> Result<Option<Vec<u8>>, Error> {
         self.get_cf_opt(cf, key.as_ref(), &ReadOptions::default())
@@ -706,7 +727,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
     /// allows specifying ColumnFamily
     pub fn get_pinned_cf_opt<K: AsRef<[u8]>>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         key: K,
         readopts: &ReadOptions,
     ) -> Result<Option<DBPinnableSlice>, Error> {
@@ -740,7 +761,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
     /// leverages default options.
     pub fn get_pinned_cf<K: AsRef<[u8]>>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         key: K,
     ) -> Result<Option<DBPinnableSlice>, Error> {
         self.get_pinned_cf_opt(cf, key, &ReadOptions::default())
@@ -791,24 +812,27 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
     }
 
     /// Return the values associated with the given keys and column families.
-    pub fn multi_get_cf<K, I, W>(&self, keys: I) -> Vec<Result<Option<Vec<u8>>, Error>>
+    pub fn multi_get_cf<'a, 'b: 'a, K, I, W: 'b>(
+        &'a self,
+        keys: I,
+    ) -> Vec<Result<Option<Vec<u8>>, Error>>
     where
         K: AsRef<[u8]>,
-        I: IntoIterator<Item = (W, K)>,
+        I: IntoIterator<Item = (&'b W, K)>,
         W: AsColumnFamilyRef,
     {
         self.multi_get_cf_opt(keys, &ReadOptions::default())
     }
 
     /// Return the values associated with the given keys and column families using read options.
-    pub fn multi_get_cf_opt<K, I, W>(
-        &self,
+    pub fn multi_get_cf_opt<'a, 'b: 'a, K, I, W: 'b>(
+        &'a self,
         keys: I,
         readopts: &ReadOptions,
     ) -> Vec<Result<Option<Vec<u8>>, Error>>
     where
         K: AsRef<[u8]>,
-        I: IntoIterator<Item = (W, K)>,
+        I: IntoIterator<Item = (&'b W, K)>,
         W: AsColumnFamilyRef,
     {
         let mut boxed_keys: Vec<Box<[u8]>> = Vec::new();
@@ -875,7 +899,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
 
     /// Returns `false` if the given key definitely doesn't exist in the specified column family,
     /// otherwise returns `true`. This function uses default `ReadOptions`.
-    pub fn key_may_exist_cf<K: AsRef<[u8]>>(&self, cf: impl AsColumnFamilyRef, key: K) -> bool {
+    pub fn key_may_exist_cf<K: AsRef<[u8]>>(&self, cf: &impl AsColumnFamilyRef, key: K) -> bool {
         self.key_may_exist_cf_opt(cf, key, &ReadOptions::default())
     }
 
@@ -883,7 +907,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
     /// otherwise returns `true`.
     pub fn key_may_exist_cf_opt<K: AsRef<[u8]>>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         key: K,
         readopts: &ReadOptions,
     ) -> bool {
@@ -945,7 +969,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
     /// This is used when you want to iterate over a specific ColumnFamily with a modified ReadOptions
     pub fn iterator_cf_opt<'a: 'b, 'b>(
         &'a self,
-        cf_handle: impl AsColumnFamilyRef,
+        cf_handle: &impl AsColumnFamilyRef,
         readopts: ReadOptions,
         mode: IteratorMode,
     ) -> DBIteratorWithThreadMode<'b, Self> {
@@ -979,7 +1003,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
 
     pub fn iterator_cf<'a: 'b, 'b>(
         &'a self,
-        cf_handle: impl AsColumnFamilyRef,
+        cf_handle: &impl AsColumnFamilyRef,
         mode: IteratorMode,
     ) -> DBIteratorWithThreadMode<'b, Self> {
         let opts = ReadOptions::default();
@@ -988,7 +1012,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
 
     pub fn full_iterator_cf<'a: 'b, 'b>(
         &'a self,
-        cf_handle: impl AsColumnFamilyRef,
+        cf_handle: &impl AsColumnFamilyRef,
         mode: IteratorMode,
     ) -> DBIteratorWithThreadMode<'b, Self> {
         let mut opts = ReadOptions::default();
@@ -998,7 +1022,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
 
     pub fn prefix_iterator_cf<'a, P: AsRef<[u8]>>(
         &'a self,
-        cf_handle: impl AsColumnFamilyRef,
+        cf_handle: &impl AsColumnFamilyRef,
         prefix: P,
     ) -> DBIteratorWithThreadMode<'a, Self> {
         let mut opts = ReadOptions::default();
@@ -1020,7 +1044,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
     /// Opens a raw iterator over the given column family, using the default read options
     pub fn raw_iterator_cf<'a: 'b, 'b>(
         &'a self,
-        cf_handle: impl AsColumnFamilyRef,
+        cf_handle: &impl AsColumnFamilyRef,
     ) -> DBRawIteratorWithThreadMode<'b, Self> {
         let opts = ReadOptions::default();
         DBRawIteratorWithThreadMode::new_cf(self, cf_handle.inner(), opts)
@@ -1037,7 +1061,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
     /// Opens a raw iterator over the given column family, using the given read options
     pub fn raw_iterator_cf_opt<'a: 'b, 'b>(
         &'a self,
-        cf_handle: impl AsColumnFamilyRef,
+        cf_handle: &impl AsColumnFamilyRef,
         readopts: ReadOptions,
     ) -> DBRawIteratorWithThreadMode<'b, Self> {
         DBRawIteratorWithThreadMode::new_cf(self, cf_handle.inner(), readopts)
@@ -1070,7 +1094,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
 
     pub fn put_cf_opt<K, V>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         key: K,
         value: V,
         writeopts: &WriteOptions,
@@ -1119,7 +1143,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
 
     pub fn merge_cf_opt<K, V>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         key: K,
         value: V,
         writeopts: &WriteOptions,
@@ -1165,7 +1189,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
 
     pub fn delete_cf_opt<K: AsRef<[u8]>>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         key: K,
         writeopts: &WriteOptions,
     ) -> Result<(), Error> {
@@ -1186,7 +1210,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
     /// Removes the database entries in the range `["from", "to")` using given write options.
     pub fn delete_range_cf_opt<K: AsRef<[u8]>>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         from: K,
         to: K,
         writeopts: &WriteOptions,
@@ -1216,7 +1240,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
         self.put_opt(key.as_ref(), value.as_ref(), &WriteOptions::default())
     }
 
-    pub fn put_cf<K, V>(&self, cf: impl AsColumnFamilyRef, key: K, value: V) -> Result<(), Error>
+    pub fn put_cf<K, V>(&self, cf: &impl AsColumnFamilyRef, key: K, value: V) -> Result<(), Error>
     where
         K: AsRef<[u8]>,
         V: AsRef<[u8]>,
@@ -1232,7 +1256,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
         self.merge_opt(key.as_ref(), value.as_ref(), &WriteOptions::default())
     }
 
-    pub fn merge_cf<K, V>(&self, cf: impl AsColumnFamilyRef, key: K, value: V) -> Result<(), Error>
+    pub fn merge_cf<K, V>(&self, cf: &impl AsColumnFamilyRef, key: K, value: V) -> Result<(), Error>
     where
         K: AsRef<[u8]>,
         V: AsRef<[u8]>,
@@ -1246,7 +1270,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
 
     pub fn delete_cf<K: AsRef<[u8]>>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         key: K,
     ) -> Result<(), Error> {
         self.delete_cf_opt(cf, key.as_ref(), &WriteOptions::default())
@@ -1255,7 +1279,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
     /// Removes the database entries in the range `["from", "to")` using default write options.
     pub fn delete_range_cf<K: AsRef<[u8]>>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         from: K,
         to: K,
     ) -> Result<(), Error> {
@@ -1304,7 +1328,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
     /// given column family. This is not likely to be needed for typical usage.
     pub fn compact_range_cf<S: AsRef<[u8]>, E: AsRef<[u8]>>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         start: Option<S>,
         end: Option<E>,
     ) {
@@ -1326,7 +1350,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
     /// Same as `compact_range_cf` but with custom options.
     pub fn compact_range_cf_opt<S: AsRef<[u8]>, E: AsRef<[u8]>>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         start: Option<S>,
         end: Option<E>,
         opts: &CompactOptions,
@@ -1365,7 +1389,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
 
     pub fn set_options_cf(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         opts: &[(&str, &str)],
     ) -> Result<(), Error> {
         let copts = convert_options(opts)?;
@@ -1426,7 +1450,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
     /// [here](https://github.com/facebook/rocksdb/blob/08809f5e6cd9cc4bc3958dd4d59457ae78c76660/include/rocksdb/db.h#L428-L634).
     pub fn property_value_cf(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         name: &str,
     ) -> Result<Option<String>, Error> {
         let prop_name = match CString::new(name) {
@@ -1484,7 +1508,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
     /// [here](https://github.com/facebook/rocksdb/blob/08809f5e6cd9cc4bc3958dd4d59457ae78c76660/include/rocksdb/db.h#L654-L689).
     pub fn property_int_value_cf(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         name: &str,
     ) -> Result<Option<u64>, Error> {
         match self.property_value_cf(cf, name) {
@@ -1561,7 +1585,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
     /// with default opts
     pub fn ingest_external_file_cf<P: AsRef<Path>>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         paths: Vec<P>,
     ) -> Result<(), Error> {
         let opts = IngestExternalFileOptions::default();
@@ -1571,7 +1595,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
     /// Loads a list of external SST files created with SstFileWriter into the DB for given Column Family
     pub fn ingest_external_file_cf_opts<P: AsRef<Path>>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         opts: &IngestExternalFileOptions,
         paths: Vec<P>,
     ) -> Result<(), Error> {
@@ -1604,7 +1628,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
 
     fn ingest_external_file_raw_cf(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         opts: &IngestExternalFileOptions,
         paths_v: &[CString],
         cpaths: &[*const c_char],
@@ -1693,7 +1717,7 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
     /// Same as `delete_file_in_range` but only for specific column family
     pub fn delete_file_in_range_cf<K: AsRef<[u8]>>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         from: K,
         to: K,
     ) -> Result<(), Error> {
@@ -1718,6 +1742,21 @@ impl<T: ThreadMode> DBWithThreadMode<T> {
             ffi::rocksdb_cancel_all_background_work(self.inner, wait as u8);
         }
     }
+
+    fn drop_column_family<C>(
+        &self,
+        cf_inner: *mut ffi::rocksdb_column_family_handle_t,
+        cf: C,
+    ) -> Result<(), Error> {
+        unsafe {
+            // first mark the column family as dropped
+            ffi_try!(ffi::rocksdb_drop_column_family(self.inner, cf_inner));
+        }
+        // then finally reclaim any resources (mem, files) by destroying the only single column
+        // family handle by drop()-ing it
+        drop(cf);
+        Ok(())
+    }
 }
 
 impl DBWithThreadMode<SingleThreaded> {
@@ -1732,12 +1771,8 @@ impl DBWithThreadMode<SingleThreaded> {
 
     /// Drops the column family with the given name
     pub fn drop_cf(&mut self, name: &str) -> Result<(), Error> {
-        let inner = self.inner;
         if let Some(cf) = self.cfs.cfs.remove(name) {
-            unsafe {
-                ffi_try!(ffi::rocksdb_drop_column_family(inner, cf.inner));
-            }
-            Ok(())
+            self.drop_column_family(cf.inner, cf)
         } else {
             Err(Error::new(format!("Invalid column family: {}", name)))
         }
@@ -1753,46 +1788,39 @@ impl DBWithThreadMode<MultiThreaded> {
     /// Creates column family with given name and options
     pub fn create_cf<N: AsRef<str>>(&self, name: N, opts: &Options) -> Result<(), Error> {
         let inner = self.create_inner_cf_handle(name.as_ref(), opts)?;
-        self.cfs
-            .cfs
-            .write()
-            .unwrap()
-            .insert(name.as_ref().to_string(), ColumnFamily { inner });
+        self.cfs.cfs.write().unwrap().insert(
+            name.as_ref().to_string(),
+            Arc::new(UnboundColumnFamily { inner }),
+        );
         Ok(())
     }
 
     /// Drops the column family with the given name by internally locking the inner column
     /// family map. This avoids needing `&mut self` reference
     pub fn drop_cf(&self, name: &str) -> Result<(), Error> {
-        let inner = self.inner;
         if let Some(cf) = self.cfs.cfs.write().unwrap().remove(name) {
-            unsafe {
-                ffi_try!(ffi::rocksdb_drop_column_family(inner, cf.inner));
-            }
-            Ok(())
+            self.drop_column_family(cf.inner, cf)
         } else {
             Err(Error::new(format!("Invalid column family: {}", name)))
         }
     }
 
     /// Returns the underlying column family handle
-    pub fn cf_handle(&self, name: &str) -> Option<BoundColumnFamily> {
+    pub fn cf_handle(&self, name: &str) -> Option<Arc<BoundColumnFamily>> {
         self.cfs
             .cfs
             .read()
             .unwrap()
             .get(name)
-            .map(|cf| BoundColumnFamily {
-                inner: cf.inner,
-                multi_threaded_cfs: PhantomData,
-            })
+            .cloned()
+            .map(UnboundColumnFamily::bound_column_family)
     }
 }
 
 impl<T: ThreadMode> Drop for DBWithThreadMode<T> {
     fn drop(&mut self) {
         unsafe {
-            self.cfs.cf_drop_all();
+            self.cfs.drop_all_cfs_internal();
             ffi::rocksdb_close(self.inner);
         }
     }

src/lib.rs

@@ -102,7 +102,7 @@ pub use crate::{
         ColumnFamilyRef, DEFAULT_COLUMN_FAMILY_NAME,
     },
     compaction_filter::Decision as CompactionDecision,
-    db::{DBWithThreadMode, LiveFile, MultiThreaded, SingleThreaded, DB},
+    db::{DBWithThreadMode, LiveFile, MultiThreaded, SingleThreaded, ThreadMode, DB},
     db_iterator::{
         DBIterator, DBIteratorWithThreadMode, DBRawIterator, DBRawIteratorWithThreadMode,
         DBWALIterator, Direction, IteratorMode,

src/snapshot.rs

@@ -61,7 +61,7 @@ impl<'a, D: DBAccess> SnapshotWithThreadMode<'a, D> {
     /// the default read options.
     pub fn iterator_cf(
         &self,
-        cf_handle: impl AsColumnFamilyRef,
+        cf_handle: &impl AsColumnFamilyRef,
         mode: IteratorMode,
     ) -> DBIteratorWithThreadMode<D> {
         let readopts = ReadOptions::default();
@@ -82,7 +82,7 @@ impl<'a, D: DBAccess> SnapshotWithThreadMode<'a, D> {
     /// the given read options.
     pub fn iterator_cf_opt(
         &self,
-        cf_handle: impl AsColumnFamilyRef,
+        cf_handle: &impl AsColumnFamilyRef,
         mut readopts: ReadOptions,
         mode: IteratorMode,
     ) -> DBIteratorWithThreadMode<D> {
@@ -100,7 +100,7 @@ impl<'a, D: DBAccess> SnapshotWithThreadMode<'a, D> {
     /// the default read options.
     pub fn raw_iterator_cf(
         &self,
-        cf_handle: impl AsColumnFamilyRef,
+        cf_handle: &impl AsColumnFamilyRef,
     ) -> DBRawIteratorWithThreadMode<D> {
         let readopts = ReadOptions::default();
         self.raw_iterator_cf_opt(cf_handle, readopts)
@@ -116,7 +116,7 @@ impl<'a, D: DBAccess> SnapshotWithThreadMode<'a, D> {
     /// the given read options.
     pub fn raw_iterator_cf_opt(
         &self,
-        cf_handle: impl AsColumnFamilyRef,
+        cf_handle: &impl AsColumnFamilyRef,
         mut readopts: ReadOptions,
     ) -> DBRawIteratorWithThreadMode<D> {
         readopts.set_snapshot(self);
@@ -133,7 +133,7 @@ impl<'a, D: DBAccess> SnapshotWithThreadMode<'a, D> {
     /// options.
     pub fn get_cf<K: AsRef<[u8]>>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         key: K,
     ) -> Result<Option<Vec<u8>>, Error> {
         let readopts = ReadOptions::default();
@@ -153,7 +153,7 @@ impl<'a, D: DBAccess> SnapshotWithThreadMode<'a, D> {
     /// Returns the bytes associated with a key value, given column family and read options.
     pub fn get_cf_opt<K: AsRef<[u8]>>(
         &self,
-        cf: impl AsColumnFamilyRef,
+        cf: &impl AsColumnFamilyRef,
         key: K,
         mut readopts: ReadOptions,
     ) -> Result<Option<Vec<u8>>, Error> {

src/write_batch.rs

@@ -134,7 +134,7 @@ impl WriteBatch {
         }
     }
 
-    pub fn put_cf<K, V>(&mut self, cf: impl AsColumnFamilyRef, key: K, value: V)
+    pub fn put_cf<K, V>(&mut self, cf: &impl AsColumnFamilyRef, key: K, value: V)
     where
         K: AsRef<[u8]>,
         V: AsRef<[u8]>,
@@ -173,7 +173,7 @@ impl WriteBatch {
         }
     }
 
-    pub fn merge_cf<K, V>(&mut self, cf: impl AsColumnFamilyRef, key: K, value: V)
+    pub fn merge_cf<K, V>(&mut self, cf: &impl AsColumnFamilyRef, key: K, value: V)
     where
         K: AsRef<[u8]>,
         V: AsRef<[u8]>,
@@ -206,7 +206,7 @@ impl WriteBatch {
         }
     }
 
-    pub fn delete_cf<K: AsRef<[u8]>>(&mut self, cf: impl AsColumnFamilyRef, key: K) {
+    pub fn delete_cf<K: AsRef<[u8]>>(&mut self, cf: &impl AsColumnFamilyRef, key: K) {
         let key = key.as_ref();
 
         unsafe {
@@ -243,7 +243,7 @@ impl WriteBatch {
     /// Removes the database entries in the range ["begin_key", "end_key"), i.e.,
     /// including "begin_key" and excluding "end_key". It is not an error if no
     /// keys exist in the range ["begin_key", "end_key").
-    pub fn delete_range_cf<K: AsRef<[u8]>>(&mut self, cf: impl AsColumnFamilyRef, from: K, to: K) {
+    pub fn delete_range_cf<K: AsRef<[u8]>>(&mut self, cf: &impl AsColumnFamilyRef, from: K, to: K) {
         let (start_key, end_key) = (from.as_ref(), to.as_ref());
 
         unsafe {

tests/test_column_family.rs

@@ -19,6 +19,25 @@ use pretty_assertions::assert_eq;
 use rocksdb::{ColumnFamilyDescriptor, MergeOperands, Options, DB, DEFAULT_COLUMN_FAMILY_NAME};
 use util::DBPath;
 
+use std::fs;
+use std::io;
+use std::path::Path;
+
+fn dir_size(path: impl AsRef<Path>) -> io::Result<u64> {
+    fn dir_size(mut dir: fs::ReadDir) -> io::Result<u64> {
+        dir.try_fold(0, |acc, file| {
+            let file = file?;
+            let size = match file.metadata()? {
+                data if data.is_dir() => dir_size(fs::read_dir(file.path())?)?,
+                data => data.len(),
+            };
+            Ok(acc + size)
+        })
+    }
+
+    dir_size(fs::read_dir(path)?)
+}
+
 #[test]
 fn test_column_family() {
     let n = DBPath::new("_rust_rocksdb_cftest");
@@ -143,15 +162,15 @@ fn test_merge_operator() {
             Err(e) => panic!("failed to open db with column family: {}", e),
         };
         let cf1 = db.cf_handle("cf1").unwrap();
-        assert!(db.put_cf(cf1, b"k1", b"v1").is_ok());
-        assert_eq!(db.get_cf(cf1, b"k1").unwrap().unwrap(), b"v1");
-        let p = db.put_cf(cf1, b"k1", b"a");
+        assert!(db.put_cf(&cf1, b"k1", b"v1").is_ok());
+        assert_eq!(db.get_cf(&cf1, b"k1").unwrap().unwrap(), b"v1");
+        let p = db.put_cf(&cf1, b"k1", b"a");
         assert!(p.is_ok());
-        db.merge_cf(cf1, b"k1", b"b").unwrap();
-        db.merge_cf(cf1, b"k1", b"c").unwrap();
-        db.merge_cf(cf1, b"k1", b"d").unwrap();
-        db.merge_cf(cf1, b"k1", b"efg").unwrap();
-        let m = db.merge_cf(cf1, b"k1", b"h");
+        db.merge_cf(&cf1, b"k1", b"b").unwrap();
+        db.merge_cf(&cf1, b"k1", b"c").unwrap();
+        db.merge_cf(&cf1, b"k1", b"d").unwrap();
+        db.merge_cf(&cf1, b"k1", b"efg").unwrap();
+        let m = db.merge_cf(&cf1, b"k1", b"h");
         println!("m is {:?}", m);
         // TODO assert!(m.is_ok());
         match db.get(b"k1") {
@@ -163,7 +182,7 @@ fn test_merge_operator() {
             _ => panic!("value not present!"),
         }
 
-        let _ = db.get_cf(cf1, b"k1");
+        let _ = db.get_cf(&cf1, b"k1");
         // TODO assert!(r.unwrap().as_ref() == b"abcdefgh");
         assert!(db.delete(b"k1").is_ok());
         assert!(db.get(b"k1").unwrap().is_none());
@@ -250,3 +269,66 @@ fn test_create_duplicate_column_family() {
         assert!(db.create_cf("cf1", &opts).is_err());
     }
 }
+
+#[test]
+fn test_no_leaked_column_family() {
+    let n = DBPath::new("_rust_rocksdb_no_leaked_column_family");
+    {
+        let mut opts = Options::default();
+        opts.create_if_missing(true);
+        opts.create_missing_column_families(true);
+
+        let mut write_options = rocksdb::WriteOptions::default();
+        write_options.set_sync(false);
+        write_options.disable_wal(true);
+
+        let mut db = DB::open(&opts, &n).unwrap();
+        let large_blob = [0x20; 1024 * 1024];
+
+        #[cfg(feature = "multi-threaded-cf")]
+        let mut outlived_cf = None;
+
+        // repeat creating and dropping cfs many time to indirectly detect
+        // possible leak via large dir.
+        for cf_index in 0..20 {
+            let cf_name = format!("cf{}", cf_index);
+            db.create_cf(&cf_name, &Options::default()).unwrap();
+            let cf = db.cf_handle(&cf_name).unwrap();
+
+            let mut batch = rocksdb::WriteBatch::default();
+            for key_index in 0..100 {
+                batch.put_cf(&cf, format!("k{}", key_index), &large_blob);
+            }
+            db.write_opt(batch, &write_options).unwrap();
+
+            // force create an SST file
+            db.flush_cf(&cf).unwrap();
+
+            db.drop_cf(&cf_name).unwrap();
+
+            #[cfg(feature = "multi-threaded-cf")]
+            {
+                outlived_cf = Some(cf);
+            }
+        }
+
+        // if we're not leaking, the dir bytes should be well under 10M bytes in total
+        let dir_bytes = dir_size(&n).unwrap();
+        assert!(
+            dir_bytes < 10_000_000,
+            "{} is too large (maybe leaking...)",
+            dir_bytes
+        );
+
+        // only if MultiThreaded, cf can outlive db.drop_cf() and shouldn't cause SEGV...
+        #[cfg(feature = "multi-threaded-cf")]
+        {
+            let outlived_cf = outlived_cf.unwrap();
+            assert_eq!(db.get_cf(&outlived_cf, "k0").unwrap().unwrap(), &large_blob);
+            drop(outlived_cf);
+        }
+
+        // make it explicit not to drop the db until we get dir size above...
+        drop(db);
+    }
+}

tests/test_db.rs

@@ -348,27 +348,27 @@ fn set_option_cf_test() {
         let cf = db.cf_handle("cf1").unwrap();
         // set an option to valid values
         assert!(db
-            .set_options_cf(cf, &[("disable_auto_compactions", "true")])
+            .set_options_cf(&cf, &[("disable_auto_compactions", "true")])
             .is_ok());
         assert!(db
-            .set_options_cf(cf, &[("disable_auto_compactions", "false")])
+            .set_options_cf(&cf, &[("disable_auto_compactions", "false")])
             .is_ok());
         // invalid names/values should result in an error
         assert!(db
-            .set_options_cf(cf, &[("disable_auto_compactions", "INVALID_VALUE")])
+            .set_options_cf(&cf, &[("disable_auto_compactions", "INVALID_VALUE")])
             .is_err());
         assert!(db
-            .set_options_cf(cf, &[("INVALID_NAME", "INVALID_VALUE")])
+            .set_options_cf(&cf, &[("INVALID_NAME", "INVALID_VALUE")])
             .is_err());
         // option names/values must not contain NULLs
         assert!(db
-            .set_options_cf(cf, &[("disable_auto_compactions", "true\0")])
+            .set_options_cf(&cf, &[("disable_auto_compactions", "true\0")])
             .is_err());
         assert!(db
-            .set_options_cf(cf, &[("disable_auto_compactions\0", "true")])
+            .set_options_cf(&cf, &[("disable_auto_compactions\0", "true")])
             .is_err());
         // empty options are not allowed
-        assert!(db.set_options_cf(cf, &[]).is_err());
+        assert!(db.set_options_cf(&cf, &[]).is_err());
         // multiple options can be set in a single API call
         let multiple_options = [
             ("paranoid_file_checks", "true"),
@@ -538,14 +538,14 @@ fn test_open_cf_with_ttl() {
     opts.create_missing_column_families(true);
     let db = DB::open_cf_with_ttl(&opts, &path, &["test_cf"], Duration::from_secs(1)).unwrap();
     let cf = db.cf_handle("test_cf").unwrap();
-    db.put_cf(cf, b"key1", b"value1").unwrap();
+    db.put_cf(&cf, b"key1", b"value1").unwrap();
 
     thread::sleep(Duration::from_secs(2));
     // Trigger a manual compaction, this will check the TTL filter
     // in the database and drop all expired entries.
-    db.compact_range_cf(cf, None::<&[u8]>, None::<&[u8]>);
+    db.compact_range_cf(&cf, None::<&[u8]>, None::<&[u8]>);
 
-    assert!(db.get_cf(cf, b"key1").unwrap().is_none());
+    assert!(db.get_cf(&cf, b"key1").unwrap().is_none());
 }
 
 #[test]
@@ -606,13 +606,13 @@ fn compact_range_test() {
         let cfs = vec!["cf1"];
         let db = DB::open_cf(&opts, &path, cfs).unwrap();
         let cf1 = db.cf_handle("cf1").unwrap();
-        db.put_cf(cf1, b"k1", b"v1").unwrap();
-        db.put_cf(cf1, b"k2", b"v2").unwrap();
-        db.put_cf(cf1, b"k3", b"v3").unwrap();
-        db.put_cf(cf1, b"k4", b"v4").unwrap();
-        db.put_cf(cf1, b"k5", b"v5").unwrap();
-        db.compact_range_cf(cf1, Some(b"k2"), Some(b"k4"));
-        db.compact_range_cf_opt(cf1, Some(b"k1"), None::<&str>, &compact_opts);
+        db.put_cf(&cf1, b"k1", b"v1").unwrap();
+        db.put_cf(&cf1, b"k2", b"v2").unwrap();
+        db.put_cf(&cf1, b"k3", b"v3").unwrap();
+        db.put_cf(&cf1, b"k4", b"v4").unwrap();
+        db.put_cf(&cf1, b"k5", b"v5").unwrap();
+        db.compact_range_cf(&cf1, Some(b"k2"), Some(b"k4"));
+        db.compact_range_cf_opt(&cf1, Some(b"k1"), None::<&str>, &compact_opts);
 
         // put and compact default column family
         db.put(b"k1", b"v1").unwrap();
@@ -645,12 +645,12 @@ fn fifo_compaction_test() {
         let cfs = vec!["cf1"];
         let db = DB::open_cf(&opts, &path, cfs).unwrap();
         let cf1 = db.cf_handle("cf1").unwrap();
-        db.put_cf(cf1, b"k1", b"v1").unwrap();
-        db.put_cf(cf1, b"k2", b"v2").unwrap();
-        db.put_cf(cf1, b"k3", b"v3").unwrap();
-        db.put_cf(cf1, b"k4", b"v4").unwrap();
-        db.put_cf(cf1, b"k5", b"v5").unwrap();
-        db.compact_range_cf(cf1, Some(b"k2"), Some(b"k4"));
+        db.put_cf(&cf1, b"k1", b"v1").unwrap();
+        db.put_cf(&cf1, b"k2", b"v2").unwrap();
+        db.put_cf(&cf1, b"k3", b"v3").unwrap();
+        db.put_cf(&cf1, b"k4", b"v4").unwrap();
+        db.put_cf(&cf1, b"k5", b"v5").unwrap();
+        db.compact_range_cf(&cf1, Some(b"k2"), Some(b"k4"));
 
         // check stats
         let ctx = PerfContext::default();
@@ -880,15 +880,15 @@ fn test_open_cf_for_read_only() {
         opts.create_missing_column_families(true);
         let db = DB::open_cf(&opts, &path, cfs.clone()).unwrap();
         let cf1 = db.cf_handle("cf1").unwrap();
-        db.put_cf(cf1, b"k1", b"v1").unwrap();
+        db.put_cf(&cf1, b"k1", b"v1").unwrap();
     }
     {
         let opts = Options::default();
         let error_if_log_file_exist = false;
         let db = DB::open_cf_for_read_only(&opts, &path, cfs, error_if_log_file_exist).unwrap();
         let cf1 = db.cf_handle("cf1").unwrap();
-        assert_eq!(db.get_cf(cf1, b"k1").unwrap().unwrap(), b"v1");
-        assert!(db.put_cf(cf1, b"k2", b"v2").is_err());
+        assert_eq!(db.get_cf(&cf1, b"k1").unwrap().unwrap(), b"v1");
+        assert!(db.put_cf(&cf1, b"k2", b"v2").is_err());
     }
 }
 
@@ -904,18 +904,18 @@ fn delete_range_test() {
         let db = DB::open_cf(&opts, &path, cfs).unwrap();
 
         let cf1 = db.cf_handle("cf1").unwrap();
-        db.put_cf(cf1, b"k1", b"v1").unwrap();
-        db.put_cf(cf1, b"k2", b"v2").unwrap();
-        db.put_cf(cf1, b"k3", b"v3").unwrap();
-        db.put_cf(cf1, b"k4", b"v4").unwrap();
-        db.put_cf(cf1, b"k5", b"v5").unwrap();
-
-        db.delete_range_cf(cf1, b"k2", b"k4").unwrap();
-        assert_eq!(db.get_cf(cf1, b"k1").unwrap().unwrap(), b"v1");
-        assert_eq!(db.get_cf(cf1, b"k4").unwrap().unwrap(), b"v4");
-        assert_eq!(db.get_cf(cf1, b"k5").unwrap().unwrap(), b"v5");
-        assert!(db.get_cf(cf1, b"k2").unwrap().is_none());
-        assert!(db.get_cf(cf1, b"k3").unwrap().is_none());
+        db.put_cf(&cf1, b"k1", b"v1").unwrap();
+        db.put_cf(&cf1, b"k2", b"v2").unwrap();
+        db.put_cf(&cf1, b"k3", b"v3").unwrap();
+        db.put_cf(&cf1, b"k4", b"v4").unwrap();
+        db.put_cf(&cf1, b"k5", b"v5").unwrap();
+
+        db.delete_range_cf(&cf1, b"k2", b"k4").unwrap();
+        assert_eq!(db.get_cf(&cf1, b"k1").unwrap().unwrap(), b"v1");
+        assert_eq!(db.get_cf(&cf1, b"k4").unwrap().unwrap(), b"v4");
+        assert_eq!(db.get_cf(&cf1, b"k5").unwrap().unwrap(), b"v5");
+        assert!(db.get_cf(&cf1, b"k2").unwrap().is_none());
+        assert!(db.get_cf(&cf1, b"k3").unwrap().is_none());
     }
 }
 
@@ -955,13 +955,13 @@ fn multi_get_cf() {
         let cf0 = db.cf_handle("cf0").unwrap();
 
         let cf1 = db.cf_handle("cf1").unwrap();
-        db.put_cf(cf1, b"k1", b"v1").unwrap();
+        db.put_cf(&cf1, b"k1", b"v1").unwrap();
 
         let cf2 = db.cf_handle("cf2").unwrap();
-        db.put_cf(cf2, b"k2", b"v2").unwrap();
+        db.put_cf(&cf2, b"k2", b"v2").unwrap();
 
         let values = db
-            .multi_get_cf(vec![(cf0, b"k0"), (cf1, b"k1"), (cf2, b"k2")])
+            .multi_get_cf(vec![(&cf0, b"k0"), (&cf1, b"k1"), (&cf2, b"k2")])
             .into_iter()
             .map(Result::unwrap)
             .collect::<Vec<_>>();
@@ -997,10 +997,10 @@ fn key_may_exist_cf() {
         let db = DB::open_cf(&opts, &path, &["cf"]).unwrap();
         let cf = db.cf_handle("cf").unwrap();
 
-        assert_eq!(false, db.key_may_exist_cf(cf, "nonexistent"));
+        assert_eq!(false, db.key_may_exist_cf(&cf, "nonexistent"));
         assert_eq!(
             false,
-            db.key_may_exist_cf_opt(cf, "nonexistent", &ReadOptions::default())
+            db.key_may_exist_cf_opt(&cf, "nonexistent", &ReadOptions::default())
         );
     }
 }

tests/test_property.rs

@@ -38,7 +38,7 @@ fn property_cf_test() {
         let mut db = DB::open_default(&n).unwrap();
         db.create_cf("cf1", &opts).unwrap();
         let cf = db.cf_handle("cf1").unwrap();
-        let value = db.property_value_cf(cf, "rocksdb.stats").unwrap().unwrap();
+        let value = db.property_value_cf(&cf, "rocksdb.stats").unwrap().unwrap();
 
         assert!(value.contains("Stats"));
     }
@@ -66,7 +66,7 @@ fn property_int_cf_test() {
         db.create_cf("cf1", &opts).unwrap();
         let cf = db.cf_handle("cf1").unwrap();
         let total_keys = db
-            .property_int_value_cf(cf, "rocksdb.estimate-num-keys")
+            .property_int_value_cf(&cf, "rocksdb.estimate-num-keys")
             .unwrap();
 
         assert_eq!(total_keys, Some(0));