cleanup for merge operators

README.md

@@ -32,6 +32,42 @@ fn main() {
 }
 ```
 
+###### Rustic Merge Operator
+```rust
+extern crate rocksdb;
+use rocksdb::{RocksDBOptions, RocksDB, MergeOperands};
+
+fn concat_merge<'a>(new_key: &[u8], existing_val: Option<&[u8]>,
+    mut operands: &mut MergeOperands) -> Vec<u8> {
+    let mut result: Vec<u8> = Vec::with_capacity(operands.size_hint().val0());
+    match existing_val {
+        Some(v) => result.push_all(v),
+        None => (),
+    }
+    for op in operands {
+        result.push_all(op);
+    }
+    result
+}
+
+fn main() {
+    let path = "/path/to/rocksdb";
+    let opts = RocksDBOptions::new();
+    opts.create_if_missing(true);
+    opts.add_merge_operator("test operator", concat_merge);
+    let db = RocksDB::open(opts, path).unwrap();
+    let p = db.put(b"k1", b"a");
+    db.merge(b"k1", b"b");
+    db.merge(b"k1", b"c");
+    db.merge(b"k1", b"d");
+    db.merge(b"k1", b"efg");
+    let r = db.get(b"k1");
+    assert!(r.unwrap().to_utf8().unwrap() == "abcdefg");
+    db.close();
+}
+```
+
+
 ### status
   - [x] basic open/put/get/delete/close
   - [x] linux support

src/lib.rs

@@ -5,7 +5,10 @@
 pub use ffi as rocksdb_ffi;
 pub use rocksdb::{
     RocksDB,
+    MergeOperands,
     RocksDBResult,
+    RocksDBOptions,
+    RocksDBVector,
 };
 pub mod rocksdb;
 pub mod ffi;

src/main.rs

@@ -1,14 +1,13 @@
 extern crate rocksdb;
 extern crate test;
-use rocksdb::RocksDB;
+use rocksdb::{RocksDBOptions, RocksDB, MergeOperands};
 use test::Bencher;
 
 #[allow(dead_code)]
 fn main() {
-    match RocksDB::open_default("/tmp/rust-rocksdb") {
+    let path = "/tmp/rust-rocksdb";
-        Ok(db) => {
+    let db = RocksDB::open_default(path).unwrap();
     assert!(db.put(b"my key", b"my value").is_ok());
-
     db.get(b"my key").map( |value| {
         match value.to_utf8() {
             Some(v) =>
@@ -21,11 +20,42 @@ fn main() {
         .on_error( |e| { println!("error retrieving value: {}", e) });
 
     assert!(db.delete(b"my key").is_ok());
-
     db.close();
-        },
+
-        Err(e) => panic!(e),
+    custom_merge();
+}
+
+#[allow(dead_code)]
+fn concat_merge(new_key: &[u8], existing_val: Option<&[u8]>,
+    mut operands: &mut MergeOperands) -> Vec<u8> {
+    let mut result: Vec<u8> = Vec::with_capacity(operands.size_hint().val0());
+    match existing_val {
+        Some(v) => result.push_all(v),
+        None => (),
     }
+    for op in operands {
+        result.push_all(op);
+    }
+    result
+}
+
+#[allow(dead_code)]
+fn custom_merge() {
+    let path = "_rust_rocksdb_mergetest";
+    let opts = RocksDBOptions::new();
+    opts.create_if_missing(true);
+    opts.add_merge_operator("test operator", concat_merge);
+    let db = RocksDB::open(opts, path).unwrap();
+    let p = db.put(b"k1", b"a");
+    db.merge(b"k1", b"b");
+    db.merge(b"k1", b"c");
+    db.merge(b"k1", b"d");
+    db.merge(b"k1", b"efg");
+    let m = db.merge(b"k1", b"h");
+    let r = db.get(b"k1");
+    assert!(r.unwrap().to_utf8().unwrap() == "abcdefgh");
+    db.close();
+    RocksDB::destroy(opts, path).is_ok();
 }
 
 #[allow(dead_code)]

src/rocksdb.rs

@@ -54,7 +54,7 @@ impl RocksDBOptions {
         }
     }
 
-    pub fn add_merge_operator<'a>(&self, name: &str, merge_fn: for <'a> fn (&[u8], Option<&[u8]>, &mut MergeOperands) -> Vec<u8>) {
+    pub fn add_merge_operator<'a>(&self, name: &str, merge_fn: fn (&[u8], Option<&[u8]>, &mut MergeOperands) -> Vec<u8>) {
         let cb = box MergeOperatorCallback {
             name: name.to_c_str(),
             merge_fn: merge_fn,
@@ -418,7 +418,7 @@ impl <'a> Iterator<&'a [u8]> for &'a mut MergeOperands<'a> {
 
 struct MergeOperatorCallback {
     name: CString,
-    merge_fn: for <'b> fn (&[u8], Option<&[u8]>, &mut MergeOperands) -> Vec<u8>,
+    merge_fn: fn (&[u8], Option<&[u8]>, &mut MergeOperands) -> Vec<u8>,
 }
 
 extern "C" fn destructor_callback(raw_cb: *mut c_void) {
@@ -479,7 +479,7 @@ extern "C" fn partial_merge_callback(
     }
 }
 
-fn test_provided_merge<'a>(new_key: &[u8], existing_val: Option<&[u8]>,
+fn test_provided_merge(new_key: &[u8], existing_val: Option<&[u8]>,
     mut operands: &mut MergeOperands) -> Vec<u8> {
     let mut result: Vec<u8> = Vec::with_capacity(operands.size_hint().val0());
     match existing_val {