Prefer rocksdb_free to free for RocksDB memory (#794)

src/db.rs

@@ -1790,7 +1790,7 @@ impl<T: ThreadMode, D: DBInner> DBCommon<T, D> {
             ))),
         };
         unsafe {
-            libc::free(value as *mut c_void);
+            ffi::rocksdb_free(value as *mut c_void);
         }
         result
     }

src/db_options.rs

@@ -2529,7 +2529,7 @@ impl Options {
 
             // Must have valid UTF-8 format.
             let s = CStr::from_ptr(value).to_str().unwrap().to_owned();
-            libc::free(value as *mut c_void);
+            ffi::rocksdb_free(value as *mut c_void);
             Some(s)
         }
     }

src/ffi_util.rs

@@ -13,7 +13,7 @@
 // limitations under the License.
 //
 
-use crate::Error;
+use crate::{ffi, Error};
 use libc::{self, c_char, c_void, size_t};
 use std::ffi::{CStr, CString};
 use std::path::Path;
@@ -38,7 +38,7 @@ pub(crate) unsafe fn raw_data(ptr: *const c_char, size: usize) -> Option<Vec<u8>
 pub fn error_message(ptr: *const c_char) -> String {
     unsafe {
         let s = from_cstr(ptr);
-        libc::free(ptr as *mut c_void);
+        ffi::rocksdb_free(ptr as *mut c_void);
         s
     }
 }
@@ -207,9 +207,10 @@ impl CSlice {
     ///
     /// # Safety
     /// The caller must ensure that the pointer and length are valid.
-    /// Moreover, `CSlice` takes the ownership of the memory and will free it using `libc::free`.
-    /// The caller must ensure that the memory is allocated by `libc::malloc`
-    /// and will not be freed by any other means.
+    /// Moreover, `CSlice` takes the ownership of the memory and will free it
+    /// using `rocksdb_free`. The caller must ensure that the memory is
+    /// allocated by `malloc` in RocksDB and will not be freed by any other
+    /// means.
     pub(crate) unsafe fn from_raw_parts(data: *const c_char, len: size_t) -> Self {
         Self { data, len }
     }
@@ -224,7 +225,7 @@ impl AsRef<[u8]> for CSlice {
 impl Drop for CSlice {
     fn drop(&mut self) {
         unsafe {
-            libc::free(self.data as *mut c_void);
+            ffi::rocksdb_free(self.data as *mut c_void);
         }
     }
 }

src/perf.rs

@@ -155,7 +155,7 @@ impl PerfContext {
             let ptr =
                 ffi::rocksdb_perfcontext_report(self.inner, c_uchar::from(exclude_zero_counters));
             let report = from_cstr(ptr);
-            libc::free(ptr as *mut c_void);
+            ffi::rocksdb_free(ptr as *mut c_void);
             report
         }
     }