Merge branch 'master' into zaidoon/revert-portable-feature

README.md

@@ -53,3 +53,10 @@ for compatibility. If you need to modify column families concurrently, enable
 the crate feature `multi-threaded-cf`, which makes this binding's
 data structures use `RwLock` by default. Alternatively, you can directly create
 `DBWithThreadMode<MultiThreaded>` without enabling the crate feature.
+
+## Switch between /MT or /MD run time library (Only for Windows)
+
+The feature `mt_static` will request the library to be built with [/MT](https://learn.microsoft.com/en-us/cpp/build/reference/md-mt-ld-use-run-time-library?view=msvc-170)
+flag, which results in library using the static version of the run-time library.
+*This can be useful in case there's a conflict in the dependecy tree between different
+run-time versions.*

src/backup.rs

@@ -48,6 +48,10 @@ pub struct RestoreOptions {
     inner: *mut ffi::rocksdb_restore_options_t,
 }
 
+// BackupEngine is a simple pointer wrapper, so it's safe to send to another thread
+// since the underlying RocksDB backup engine is thread-safe.
+unsafe impl Send for BackupEngine {}
+
 impl BackupEngine {
     /// Open a backup engine with the specified options and RocksDB Env.
     pub fn open(opts: &BackupEngineOptions, env: &Env) -> Result<Self, Error> {

tests/test_backup.rs

@@ -107,3 +107,10 @@ fn restore_from_backup() {
         }
     }
 }
+
+fn assert_send_generic<T: Send>() {}
+
+#[test]
+fn assert_send() {
+    assert_send_generic::<BackupEngine>();
+}