Allow RocksDB to be shared across threads

src/rocksdb.rs

@@ -32,6 +32,9 @@ pub struct RocksDB {
     inner: rocksdb_ffi::RocksDBInstance,
 }
 
+unsafe impl Send for RocksDB {}
+unsafe impl Sync for RocksDB {}
+
 pub struct WriteBatch {
     inner: rocksdb_ffi::RocksDBWriteBatch,
 }
@@ -159,9 +162,9 @@ impl <'a> Drop for Snapshot<'a> {
 
 // This is for the RocksDB and write batches to share the same API
 pub trait Writable {
-    fn put(&mut self, key: &[u8], value: &[u8]) -> Result<(), String>;
+    fn put(&self, key: &[u8], value: &[u8]) -> Result<(), String>;
-    fn merge(&mut self, key: &[u8], value: &[u8]) -> Result<(), String>;
+    fn merge(&self, key: &[u8], value: &[u8]) -> Result<(), String>;
-    fn delete(&mut self, key: &[u8]) -> Result<(), String>;
+    fn delete(&self, key: &[u8]) -> Result<(), String>;
 }
 
 fn error_message(ptr: *const i8) -> String {
@@ -308,7 +311,7 @@ impl RocksDB {
 }
 
 impl Writable for RocksDB {
-    fn put(&mut self, key: &[u8], value: &[u8]) -> Result<(), String> {
+    fn put(&self, key: &[u8], value: &[u8]) -> Result<(), String> {
         unsafe {
             let writeopts = rocksdb_ffi::rocksdb_writeoptions_create();
             let mut err: *const i8 = 0 as *const i8;
@@ -324,7 +327,7 @@ impl Writable for RocksDB {
         }
     }
 
-    fn merge(&mut self, key: &[u8], value: &[u8]) -> Result<(), String> {
+    fn merge(&self, key: &[u8], value: &[u8]) -> Result<(), String> {
         unsafe {
             let writeopts = rocksdb_ffi::rocksdb_writeoptions_create();
             let mut err: *const i8 = 0 as *const i8;
@@ -340,7 +343,7 @@ impl Writable for RocksDB {
         }
     }
 
-    fn delete(&mut self, key: &[u8]) -> Result<(), String> {
+    fn delete(&self, key: &[u8]) -> Result<(), String> {
         unsafe {
             let writeopts = rocksdb_ffi::rocksdb_writeoptions_create();
             let mut err: *const i8 = 0 as *const i8;
@@ -381,7 +384,7 @@ impl Drop for RocksDB {
 }
 
 impl Writable for WriteBatch {
-    fn put(&mut self, key: &[u8], value: &[u8]) -> Result<(), String> {
+    fn put(&self, key: &[u8], value: &[u8]) -> Result<(), String> {
         unsafe {
             rocksdb_ffi::rocksdb_writebatch_put(self.inner, key.as_ptr(),
                         key.len() as size_t, value.as_ptr(),
@@ -390,7 +393,7 @@ impl Writable for WriteBatch {
         }
     }
 
-    fn merge(&mut self, key: &[u8], value: &[u8]) -> Result<(), String> {
+    fn merge(&self, key: &[u8], value: &[u8]) -> Result<(), String> {
         unsafe {
             rocksdb_ffi::rocksdb_writebatch_merge(self.inner, key.as_ptr(),
                         key.len() as size_t, value.as_ptr(),
@@ -399,7 +402,7 @@ impl Writable for WriteBatch {
         }
     }
 
-    fn delete(&mut self, key: &[u8]) -> Result<(), String> {
+    fn delete(&self, key: &[u8]) -> Result<(), String> {
         unsafe {
             rocksdb_ffi::rocksdb_writebatch_delete(self.inner, key.as_ptr(),
                         key.len() as size_t);

test/test.rs

@@ -1,3 +1,4 @@
 extern crate rocksdb;
 
 mod test_iterator;
+mod test_multithreaded;

test/test_multithreaded.rs

@@ -0,0 +1,48 @@
+use rocksdb::{Options, RocksDB, Writable, Direction, RocksDBResult};
+use std::thread::{self, Builder};
+use std::sync::Arc;
+
+const N: usize = 1000_000;
+
+#[test]
+pub fn test_multithreaded() {
+    let path = "_rust_rocksdb_multithreadtest";
+    let db = RocksDB::open_default(path).unwrap();
+    let db = Arc::new(db);
+
+    db.put(b"key", b"value1");
+
+    let db1 = db.clone();
+    let j1 = thread::spawn(move|| {
+        for i in 1..N {
+            db1.put(b"key", b"value1");
+        }
+    });
+
+    let db2 = db.clone();
+    let j2 = thread::spawn(move|| {
+        for i in 1..N {
+            db2.put(b"key", b"value2");
+        }
+    });
+
+    let db3 = db.clone();
+    let j3 = thread::spawn(move|| {
+        for i in 1..N {
+            match db3.get(b"key") {
+                RocksDBResult::Some(v) => {
+                    if &v[..] != b"value1" && &v[..] != b"value2" {
+                        assert!(false);
+                    }
+                }
+                _ => {
+                    assert!(false);
+                }
+            }
+        }
+    });
+
+    j1.join();
+    j2.join();
+    j3.join();
+}