add more configuration capabilities

README.md

@@ -67,6 +67,41 @@ fn main() {
 }
 ```
 
+###### Apply Some Tunings
+Please read [the official tuning guide](https://github.com/facebook/rocksdb/wiki/RocksDB-Tuning-Guide), and most importantly, measure performance under realistic workloads with realistic hardware.
+```rust
+use rocksdb::{RocksDBOptions, RocksDB, new_bloom_filter};
+use rocksdb::RocksDBCompactionStyle::RocksDBUniversalCompaction;
+
+fn tuned_for_somebody_elses_disk() -> RocksDB {
+    let path = "_rust_rocksdb_optimizetest";
+    let opts = RocksDBOptions::new();
+    opts.create_if_missing(true);
+    opts.set_block_size(524288);
+    opts.set_max_open_files(10000);
+    opts.set_use_fsync(false);
+    opts.set_bytes_per_sync(8388608);
+    opts.set_disable_data_sync(false);
+    opts.set_block_cache_size_mb(1024);
+    opts.set_table_cache_num_shard_bits(6);
+    opts.set_max_write_buffer_number(32);
+    opts.set_write_buffer_size(536870912);
+    opts.set_target_file_size_base(1073741824);
+    opts.set_min_write_buffer_number_to_merge(4);
+    opts.set_level_zero_stop_writes_trigger(2000);
+    opts.set_level_zero_slowdown_writes_trigger(0);
+    opts.set_compaction_style(RocksDBUniversalCompaction);
+    opts.set_max_background_compactions(4);
+    opts.set_max_background_flushes(4);
+    opts.set_filter_deletes(false);
+    opts.set_disable_auto_compactions(true);
+
+    let filter = new_bloom_filter(10);
+    opts.set_filter(filter);
+
+    RocksDB::open(opts, path).unwrap()
+}
+```
 
 ### status
   - [x] basic open/put/get/delete/close

src/ffi.rs

@@ -10,12 +10,20 @@ pub struct RocksDBWriteOptions(pub *const c_void);
 #[repr(C)]
 pub struct RocksDBReadOptions(pub *const c_void);
 #[repr(C)]
-pub struct RocksDBCompactionFilter(pub *const c_void);
-#[repr(C)]
 pub struct RocksDBMergeOperator(pub *const c_void);
 #[repr(C)]
+pub struct RocksDBBlockBasedTableOptions(pub *const c_void);
+#[repr(C)]
+pub struct RocksDBCache(pub *const c_void);
+#[repr(C)]
 pub struct RocksDBFilterPolicy(pub *const c_void);
 
+pub fn new_bloom_filter(bits: c_int) -> RocksDBFilterPolicy {
+    unsafe {
+        rocksdb_filterpolicy_create_bloom(bits)
+    }
+}
+
 #[repr(C)]
 pub enum RocksDBCompressionType {
     RocksDBNoCompression     = 0,
@@ -42,12 +50,41 @@ pub enum RocksDBUniversalCompactionStyle {
 #[link(name = "rocksdb")]
 extern {
     pub fn rocksdb_options_create() -> RocksDBOptions;
+    pub fn rocksdb_cache_create_lru(capacity: size_t) -> RocksDBCache;
+    pub fn rocksdb_cache_destroy(cache: RocksDBCache);
+    pub fn rocksdb_block_based_options_create() -> RocksDBBlockBasedTableOptions;
+    pub fn rocksdb_block_based_options_destroy(
+        block_options: RocksDBBlockBasedTableOptions);
+    pub fn rocksdb_block_based_options_set_block_size(
+        block_options: RocksDBBlockBasedTableOptions,
+        block_size: size_t);
+    pub fn rocksdb_block_based_options_set_block_size_deviation(
+        block_options: RocksDBBlockBasedTableOptions,
+        block_size_deviation: c_int);
+    pub fn rocksdb_block_based_options_set_block_restart_interval(
+        block_options: RocksDBBlockBasedTableOptions,
+        block_restart_interval: c_int);
+    pub fn rocksdb_block_based_options_set_filter_policy(
+        block_options: RocksDBBlockBasedTableOptions,
+        filter_policy: RocksDBFilterPolicy);
+    pub fn rocksdb_block_based_options_set_no_block_cache(
+        block_options: RocksDBBlockBasedTableOptions, no_block_cache: bool);
+    pub fn rocksdb_block_based_options_set_block_cache(
+        block_options: RocksDBBlockBasedTableOptions, block_cache: RocksDBCache);
+    pub fn rocksdb_block_based_options_set_block_cache_compressed(
+        block_options: RocksDBBlockBasedTableOptions,
+        block_cache_compressed: RocksDBCache);
+    pub fn rocksdb_block_based_options_set_whole_key_filtering(
+        ck_options: RocksDBBlockBasedTableOptions, doit: bool);
+    pub fn rocksdb_options_set_block_based_table_factory(
+        options: RocksDBOptions,
+        block_options: RocksDBBlockBasedTableOptions);
     pub fn rocksdb_options_increase_parallelism(
         options: RocksDBOptions, threads: c_int);
     pub fn rocksdb_options_optimize_level_style_compaction(
         options: RocksDBOptions, memtable_memory_budget: c_int);
     pub fn rocksdb_options_set_create_if_missing(
-        options: RocksDBOptions, v: c_int);
+        options: RocksDBOptions, v: bool);
     pub fn rocksdb_options_set_max_open_files(
         options: RocksDBOptions, files: c_int);
     pub fn rocksdb_options_set_use_fsync(
@@ -59,11 +96,9 @@ extern {
     pub fn rocksdb_options_optimize_for_point_lookup(
         options: RocksDBOptions, block_cache_size_mb: u64);
     pub fn rocksdb_options_set_table_cache_numshardbits(
-        options: RocksDBOptions, bits: u64);
+        options: RocksDBOptions, bits: c_int);
     pub fn rocksdb_options_set_max_write_buffer_number(
         options: RocksDBOptions, bufno: c_int);
-    pub fn rocksdb_options_set_max_write_buffer_number_to_merge(
-        options: RocksDBOptions, bufno: c_int);
     pub fn rocksdb_options_set_min_write_buffer_number_to_merge(
         options: RocksDBOptions, bufno: c_int);
     pub fn rocksdb_options_set_level0_file_num_compaction_trigger(
@@ -93,10 +128,9 @@ extern {
     pub fn rocksdb_options_set_max_background_flushes(
         options: RocksDBOptions, max_bg_flushes: c_int);
     pub fn rocksdb_options_set_filter_deletes(
-        options: RocksDBOptions, v: u8);
+        options: RocksDBOptions, v: bool);
     pub fn rocksdb_options_set_disable_auto_compactions(
-        options: RocksDBOptions, v: u8);
-    //pub fn rocksdb_compactionfilter_create() -> RocksDBCompactionFilter;
+        options: RocksDBOptions, v: c_int);
     pub fn rocksdb_filterpolicy_create_bloom(
         bits_per_key: c_int) -> RocksDBFilterPolicy;
     pub fn rocksdb_open(options: RocksDBOptions,
@@ -156,7 +190,7 @@ fn internal() {
 
         rocksdb_options_increase_parallelism(opts, 0);
         rocksdb_options_optimize_level_style_compaction(opts, 0);
-        rocksdb_options_set_create_if_missing(opts, 1);
+        rocksdb_options_set_create_if_missing(opts, true);
 
         let rustpath = "_rust_rocksdb_internaltest";
         let cpath = rustpath.to_c_str();

src/lib.rs

@@ -4,6 +4,7 @@
 
 pub use ffi as rocksdb_ffi;
 pub use ffi::{
+    new_bloom_filter,
     RocksDBUniversalCompactionStyle,
     RocksDBCompactionStyle,
     RocksDBCompressionType,

src/main.rs

 extern crate rocksdb;
 extern crate test;
-use rocksdb::{RocksDBOptions, RocksDB, MergeOperands};
+use rocksdb::{RocksDBOptions, RocksDB, MergeOperands, new_bloom_filter};
 use rocksdb::RocksDBCompactionStyle::RocksDBUniversalCompaction;
 use test::Bencher;
 
@@ -24,7 +24,6 @@ fn main() {
     db.close();
 
     custom_merge();
-    optimized();
 }
 
 #[allow(dead_code)]
@@ -61,7 +60,7 @@ fn custom_merge() {
 }
 
 #[allow(dead_code)]
-fn optimized() {
+fn tuned_for_somebody_elses_disk() -> RocksDB {
     let path = "_rust_rocksdb_optimizetest";
     let opts = RocksDBOptions::new();
     opts.create_if_missing(true);
@@ -70,7 +69,7 @@ fn optimized() {
     opts.set_use_fsync(false);
     opts.set_bytes_per_sync(8388608);
     opts.set_disable_data_sync(false);
-    opts.set_cache_size(8589934592);
+    opts.set_block_cache_size_mb(1024);
     opts.set_table_cache_num_shard_bits(6);
     opts.set_max_write_buffer_number(32);
     opts.set_write_buffer_size(536870912);
@@ -78,32 +77,22 @@ fn optimized() {
     opts.set_min_write_buffer_number_to_merge(4);
     opts.set_level_zero_stop_writes_trigger(2000);
     opts.set_level_zero_slowdown_writes_trigger(0);
-    //opts.set_memtable_config(newSkipListMemTableConfig());
     opts.set_compaction_style(RocksDBUniversalCompaction);
     opts.set_max_background_compactions(4);
     opts.set_max_background_flushes(4);
     opts.set_filter_deletes(false);
-    opts.set_disable_auto_compaction(true);
-    //opts.set_filter(filter);
+    opts.set_disable_auto_compactions(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();
+    let filter = new_bloom_filter(10);
+    opts.set_filter(filter);
+
+    RocksDB::open(opts, path).unwrap()
 }
 
 #[allow(dead_code)]
 #[bench]
 fn writes(b: &mut Bencher) {
-    let db = RocksDB::open_default("testdb").unwrap();
+    let db = tuned_for_somebody_elses_disk();
     let mut i = 0 as u64;
     b.iter(|| {
         db.put(i.to_string().as_bytes(), b"v1111");
@@ -115,7 +104,7 @@ fn writes(b: &mut Bencher) {
 #[allow(dead_code)]
 #[bench]
 fn reads(b: &mut Bencher) {
-    let db = RocksDB::open_default("testdb").unwrap();
+    let db = tuned_for_somebody_elses_disk();
     let mut i = 0 as u64;
     b.iter(|| {
         db.get(i.to_string().as_bytes()).on_error( |e| {

src/rocksdb.rs

@@ -13,6 +13,7 @@ use rocksdb_ffi;
 
 pub struct RocksDBOptions {
     inner: rocksdb_ffi::RocksDBOptions,
+    block_options: rocksdb_ffi::RocksDBBlockBasedTableOptions,
 }
 
 impl RocksDBOptions {
@@ -23,8 +24,12 @@ impl RocksDBOptions {
             if opt_ptr.is_null() {
                 panic!("Could not create rocksdb options".to_string());
             }
+            let block_opts = rocksdb_ffi::rocksdb_block_based_options_create();
 
-            RocksDBOptions{inner: opts}
+            RocksDBOptions{
+                inner: opts,
+                block_options: block_opts,
+            }
         }
     }
 
@@ -45,16 +50,13 @@ impl RocksDBOptions {
 
     pub fn create_if_missing(&self, create_if_missing: bool) {
         unsafe {
-            match create_if_missing {
-                true => rocksdb_ffi::rocksdb_options_set_create_if_missing(
-                    self.inner, 1),
-                false => rocksdb_ffi::rocksdb_options_set_create_if_missing(
-                    self.inner, 0),
-            }
+            rocksdb_ffi::rocksdb_options_set_create_if_missing(
+                self.inner, create_if_missing);
         }
     }
 
-    pub fn add_merge_operator<'a>(&self, name: &str, merge_fn: 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,
@@ -72,33 +74,33 @@ impl RocksDBOptions {
         }
     }
 
-    /* block based table options
     pub fn set_block_size(&self, size: u64) {
         unsafe {
-            rocksdb_ffi::rocksdb_block_based_options_set_block_size(self.table_options, size);
-        }
-    }
-
-    pub fn set_cache_size(&self, cache_size: u64) {
-        unsafe {
-            rocksdb_ffi::rocksdb_options_set(self.inner, );
+            rocksdb_ffi::rocksdb_block_based_options_set_block_size(
+                self.block_options, size);
+            rocksdb_ffi::rocksdb_options_set_block_based_table_factory(
+                self.inner,
+                self.block_options);
         }
     }
 
-    pub fn set_memtable_config(&self,newSkipListMemTableConfig()) {
+    pub fn set_block_cache_size_mb(&self, cache_size: u64) {
         unsafe {
-            rocksdb_ffi::rocksdb_options_set(self.inner, );
+            rocksdb_ffi::rocksdb_options_optimize_for_point_lookup(
+                self.inner, cache_size);
         }
     }
 
-    pub fn set_filter(&self, filter: RocksDBFilterPolicy) {
+    pub fn set_filter(&self, filter: rocksdb_ffi::RocksDBFilterPolicy) {
         unsafe {
-            rocksdb_ffi::rocksdb_block_based_options_set_filter_policy(self.inner, filter);
+            rocksdb_ffi::rocksdb_block_based_options_set_filter_policy(
+                self.block_options, filter);
+            rocksdb_ffi::rocksdb_options_set_block_based_table_factory(
+                self.inner,
+                self.block_options);
         }
     }
 
-    */
-
     pub fn set_max_open_files(&self, nfiles: c_int) {
         unsafe {
             rocksdb_ffi::rocksdb_options_set_max_open_files(self.inner, nfiles);
@@ -108,17 +110,18 @@ impl RocksDBOptions {
     pub fn set_use_fsync(&self, useit: bool) {
         unsafe {
             match useit {
-                true => rocksdb_ffi::rocksdb_options_set_use_fsync(
-                    self.inner, 1),
-                false => rocksdb_ffi::rocksdb_options_set_use_fsync(
-                    self.inner, 0),
+                true =>
+                    rocksdb_ffi::rocksdb_options_set_use_fsync(self.inner, 1),
+                false =>
+                    rocksdb_ffi::rocksdb_options_set_use_fsync(self.inner, 0),
             }
         }
     }
 
     pub fn set_bytes_per_sync(&self, nbytes: u64) {
         unsafe {
-            rocksdb_ffi::rocksdb_options_set_bytes_per_sync(self.inner, nbytes);
+            rocksdb_ffi::rocksdb_options_set_bytes_per_sync(
+                self.inner, nbytes);
         }
     }
 
@@ -126,88 +129,110 @@ impl RocksDBOptions {
         unsafe {
             match disable {
                 true =>
-                    rocksdb_ffi::rocksdb_options_set_disable_data_sync(self.inner, 1),
+                    rocksdb_ffi::rocksdb_options_set_disable_data_sync(
+                        self.inner, 1),
                 false =>
-                    rocksdb_ffi::rocksdb_options_set_disable_data_sync(self.inner, 0),
+                    rocksdb_ffi::rocksdb_options_set_disable_data_sync(
+                        self.inner, 0),
             }
         }
     }
 
     pub fn set_table_cache_num_shard_bits(&self, nbits: c_int) {
         unsafe {
-            rocksdb_ffi::rocksdb_options_set_table_cache_numshardbits(self.inner, nbits);
+            rocksdb_ffi::rocksdb_options_set_table_cache_numshardbits(
+                self.inner, nbits);
         }
     }
 
     pub fn set_min_write_buffer_number(&self, nbuf: c_int) {
         unsafe {
-            rocksdb_ffi::rocksdb_options_set_min_write_buffer_number_to_merge(self.inner, nbuf);
+            rocksdb_ffi::rocksdb_options_set_min_write_buffer_number_to_merge(
+                self.inner, nbuf);
         }
     }
 
     pub fn set_max_write_buffer_number(&self, nbuf: c_int) {
         unsafe {
-            rocksdb_ffi::rocksdb_options_set_max_write_buffer_number_to_merge(self.inner, nbuf);
+            rocksdb_ffi::rocksdb_options_set_max_write_buffer_number(
+                self.inner, nbuf);
         }
     }
 
     pub fn set_write_buffer_size(&self, size: size_t) {
         unsafe {
-            rocksdb_ffi::rocksdb_options_set_write_buffer_size(self.inner, size);
+            rocksdb_ffi::rocksdb_options_set_write_buffer_size(
+                self.inner, size);
         }
     }
 
     pub fn set_target_file_size_base(&self, size: u64) {
         unsafe {
-            rocksdb_ffi::rocksdb_options_set_target_file_size_base(self.inner, size);
+            rocksdb_ffi::rocksdb_options_set_target_file_size_base(
+                self.inner, size);
         }
     }
 
     pub fn set_min_write_buffer_number_to_merge(&self, to_merge: c_int) {
         unsafe {
-            rocksdb_ffi::rocksdb_options_set_min_write_buffer_number_to_merge(self.inner, to_merge);
+            rocksdb_ffi::rocksdb_options_set_min_write_buffer_number_to_merge(
+                self.inner, to_merge);
         }
     }
 
     pub fn set_level_zero_slowdown_writes_trigger(&self, n: c_int) {
         unsafe {
-            rocksdb_ffi::rocksdb_options_set_level0_slowdown_writes_trigger(self.inner, n);
+            rocksdb_ffi::rocksdb_options_set_level0_slowdown_writes_trigger(
+                self.inner, n);
         }
     }
 
     pub fn set_level_zero_stop_writes_trigger(&self, n: c_int) {
         unsafe {
-            rocksdb_ffi::rocksdb_options_set_level0_stop_writes_trigger(self.inner, n);
+            rocksdb_ffi::rocksdb_options_set_level0_stop_writes_trigger(
+                self.inner, n);
         }
     }
 
-    pub fn set_compaction_style(&self, style: rocksdb_ffi::RocksDBCompactionStyle) {
+    pub fn set_compaction_style(&self, style:
+                                rocksdb_ffi::RocksDBCompactionStyle) {
         unsafe {
-            rocksdb_ffi::rocksdb_options_set_compaction_style(self.inner, style);
+            rocksdb_ffi::rocksdb_options_set_compaction_style(
+                self.inner, style);
         }
     }
 
     pub fn set_max_background_compactions(&self, n: c_int) {
         unsafe {
-            rocksdb_ffi::rocksdb_options_set_max_background_compactions(self.inner, n);
+            rocksdb_ffi::rocksdb_options_set_max_background_compactions(
+                self.inner, n);
         }
     }
 
     pub fn set_max_background_flushes(&self, n: c_int) {
         unsafe {
-            rocksdb_ffi::rocksdb_options_set_max_background_flushes(self.inner, n);
+            rocksdb_ffi::rocksdb_options_set_max_background_flushes(
+                self.inner, n);
         }
     }
 
-    pub fn set_filter_deletes(&self, filter: bool) { // to u8
+    pub fn set_filter_deletes(&self, filter: bool) {
         unsafe {
-            rocksdb_ffi::rocksdb_options_set_filter_deletes(self.inner, filter);
+            rocksdb_ffi::rocksdb_options_set_filter_deletes(
+                self.inner, filter);
         }
     }
 
     pub fn set_disable_auto_compactions(&self, disable: bool) {
         unsafe {
-            rocksdb_ffi::rocksdb_options_set_disable_auto_compactions(self.inner, disable);
+            match disable {
+                true =>
+                    rocksdb_ffi::rocksdb_options_set_disable_auto_compactions(
+                        self.inner, 1),
+                false =>
+                    rocksdb_ffi::rocksdb_options_set_disable_auto_compactions(
+                        self.inner, 0),
+            }
         }
     }
 }
@@ -240,7 +265,8 @@ impl RocksDB {
                     Some(error_string) =>
                         return Err(error_string.to_string()),
                     None =>
-                        return Err("Could not initialize database.".to_string()),
+                        return Err(
+                            "Could not initialize database.".to_string()),
                 }
             }
             if db_ptr.is_null() {
@@ -259,14 +285,16 @@ impl RocksDB {
             //     process currently
 
             let err = 0 as *mut i8;
-            let result = rocksdb_ffi::rocksdb_destroy_db(opts.inner, cpath_ptr, err);
+            let result = rocksdb_ffi::rocksdb_destroy_db(
+                opts.inner, cpath_ptr, err);
             if err.is_not_null() {
                 let cs = CString::new(err as *const i8, true);
                 match cs.as_str() {
                     Some(error_string) =>
                         return Err(error_string.to_string()),
                     None =>
-                        return Err("Could not initialize database.".to_string()),
+                        return Err(
+                            "Could not initialize database.".to_string()),
                 }
             }
             Ok(())
@@ -514,7 +542,8 @@ pub struct MergeOperands<'a> {
 }
 
 impl <'a> MergeOperands<'a> {
-    fn new<'a>(operands_list: *const *const c_char, operands_list_len: *const size_t,
+    fn new<'a>(operands_list: *const *const c_char,
+               operands_list_len: *const size_t,
                num_operands: c_int) -> MergeOperands<'a> {
         assert!(num_operands >= 0);
         MergeOperands {
@@ -537,13 +566,15 @@ impl <'a> Iterator<&'a [u8]> for &'a mut MergeOperands<'a> {
                     let base_len = self.operands_list_len as uint;
                     let spacing = mem::size_of::<*const *const u8>();
                     let spacing_len = mem::size_of::<*const size_t>();
-                    let len_ptr = (base_len + (spacing_len * self.cursor)) as *const size_t;
+                    let len_ptr = (base_len + (spacing_len * self.cursor))
+                        as *const size_t;
                     let len = *len_ptr as uint;
                     let ptr = base + (spacing * self.cursor);
                     let op = from_buf_len(*(ptr as *const *const u8), len);
                     let des: Option<uint> = from_str(op.as_slice());
                     self.cursor += 1;
-                    Some(mem::transmute(Slice{data:*(ptr as *const *const u8) as *const u8, len: len}))
+                    Some(mem::transmute(Slice{data:*(ptr as *const *const u8)
+                        as *const u8, len: len}))
                 }
             }
         }
@@ -568,7 +599,8 @@ extern "C" fn destructor_callback(raw_cb: *mut c_void) {
 
 extern "C" fn name_callback(raw_cb: *mut c_void) -> *const c_char {
     unsafe {
-        let cb: &mut MergeOperatorCallback = &mut *(raw_cb as *mut MergeOperatorCallback);
+        let cb: &mut MergeOperatorCallback =
+            &mut *(raw_cb as *mut MergeOperatorCallback);
         let ptr = cb.name.as_ptr();
         ptr as *const c_char
     }
@@ -581,11 +613,17 @@ extern "C" fn full_merge_callback(
     num_operands: c_int,
     success: *mut u8, new_value_length: *mut size_t) -> *const c_char {
     unsafe {
-        let cb: &mut MergeOperatorCallback = &mut *(raw_cb as *mut MergeOperatorCallback);
-        let operands = &mut MergeOperands::new(operands_list, operands_list_len, num_operands);
+        let cb: &mut MergeOperatorCallback =
+            &mut *(raw_cb as *mut MergeOperatorCallback);
+        let operands =
+            &mut MergeOperands::new(operands_list,
+                                    operands_list_len,
+                                    num_operands);
         let key = from_buf_len(key as *const u8, key_len as uint);
-        let oldval = from_buf_len(existing_value as *const u8, existing_value_len as uint);
-        let mut result = (cb.merge_fn)(key.as_bytes(), Some(oldval.as_bytes()), operands);
+        let oldval = from_buf_len(existing_value as *const u8,
+                                  existing_value_len as uint);
+        let mut result =
+            (cb.merge_fn)(key.as_bytes(), Some(oldval.as_bytes()), operands);
         result.shrink_to_fit();
         /*
         let ptr = result.as_ptr();
@@ -597,7 +635,8 @@ extern "C" fn full_merge_callback(
         assert!(buf.is_not_null());
         *new_value_length = result.len() as size_t;
         *success = 1 as u8;
-        ptr::copy_memory(&mut *buf, result.as_ptr() as *const c_void, result.len());
+        ptr::copy_memory(&mut *buf, result.as_ptr()
+                         as *const c_void, result.len());
         buf as *const c_char
     }
 }
@@ -608,8 +647,11 @@ extern "C" fn partial_merge_callback(
     num_operands: c_int,
     success: *mut u8, new_value_length: *mut size_t) -> *const c_char {
     unsafe {
-        let cb: &mut MergeOperatorCallback = &mut *(raw_cb as *mut MergeOperatorCallback);
-        let operands = &mut MergeOperands::new(operands_list, operands_list_len, num_operands);
+        let cb: &mut MergeOperatorCallback =
+            &mut *(raw_cb as *mut MergeOperatorCallback);
+        let operands = &mut MergeOperands::new(operands_list,
+                                               operands_list_len,
+                                               num_operands);
         let key = from_buf_len(key as *const u8, key_len as uint);
         let mut result = (cb.merge_fn)(key.as_bytes(), None, operands);
         result.shrink_to_fit();
@@ -618,7 +660,8 @@ extern "C" fn partial_merge_callback(
         assert!(buf.is_not_null());
         *new_value_length = 1 as size_t;
         *success = 1 as u8;
-        ptr::copy_memory(&mut *buf, result.as_ptr() as *const c_void, result.len());
+        ptr::copy_memory(&mut *buf, result.as_ptr()
+                         as *const c_void, result.len());
         buf as *const c_char
     }
 }