Merge pull request #9 from xyb/batch

add batch procedure and cache option

src/leveldb.nim

@@ -6,6 +6,10 @@ type
     syncWriteOptions: ptr leveldb_writeoptions_t
     asyncWriteOptions: ptr leveldb_writeoptions_t
     readOptions: ptr leveldb_readoptions_t
+    cache: ptr leveldb_cache_t
+
+  LevelDbBatch* = ref object
+    batch: ptr leveldb_writebatch_t
 
   LevelDbException* = object of Exception
 
@@ -33,9 +37,12 @@ proc close*(self: LevelDb) =
   leveldb_writeoptions_destroy(self.syncWriteOptions)
   leveldb_writeoptions_destroy(self.asyncWriteOptions)
   leveldb_readoptions_destroy(self.readOptions)
+  if self.cache != nil:
+    leveldb_cache_destroy(self.cache)
+    self.cache = nil
   self.db = nil
 
-proc open*(path: string): LevelDb =
+proc open*(path: string, cacheCapacity = 0): LevelDb =
   new(result, close)
 
   let options = leveldb_options_create()
@@ -48,6 +55,11 @@ proc open*(path: string): LevelDb =
   leveldb_writeoptions_set_sync(result.asyncWriteOptions, levelDbFalse)
   result.readOptions = leveldb_readoptions_create()
 
+  if cacheCapacity > 0:
+    let cache = leveldb_cache_create_lru(cacheCapacity)
+    leveldb_options_set_cache(options, cache)
+    result.cache = cache
+
   var errPtr: cstring = nil
   result.db = leveldb_open(options, path, addr errPtr)
   checkError(errPtr)
@@ -82,6 +94,33 @@ proc delete*(self: LevelDb, key: string, sync = true) =
   leveldb_delete(self.db, writeOptions, key, key.len, addr errPtr)
   checkError(errPtr)
 
+proc destroy*(self: LevelDbBatch) =
+  if self.batch == nil:
+    return
+  leveldb_writebatch_destroy(self.batch)
+  self.batch = nil
+
+proc newBatch*(): LevelDbBatch =
+  new(result, destroy)
+  result.batch = leveldb_writebatch_create()
+
+proc put*(self: LevelDbBatch, key: string, value: string, sync = true) =
+  leveldb_writebatch_put(self.batch, key, key.len.csize, value, value.len.csize)
+
+proc append*(self, source: LevelDbBatch) =
+  leveldb_writebatch_append(self.batch, source.batch)
+
+proc delete*(self: LevelDbBatch, key: string) =
+  leveldb_writebatch_delete(self.batch, key, key.len.csize)
+
+proc clear*(self: LevelDbBatch) =
+  leveldb_writebatch_clear(self.batch)
+
+proc write*(self: LevelDb, batch: LevelDbBatch) =
+  var errPtr: cstring = nil
+  leveldb_write(self.db, self.syncWriteOptions, batch.batch, addr errPtr)
+  checkError(errPtr)
+
 proc getIterData(iterPtr: ptr leveldb_iterator_t): (Option[string], Option[string]) =
   var len: csize
   var str: cstring

tests/test.nim

@@ -76,3 +76,36 @@ suite "leveldb":
     db.put("\0z1", "\0ff")
     db.put("z2\0", "ff\0")
     check(toSeq(db.iter()) == @[("\0z1", "\0ff"), ("z2\0", "ff\0")])
+
+  test "batch":
+    db.put("a", "1")
+    db.put("b", "2")
+    let batch = newBatch()
+    batch.put("a", "10")
+    batch.put("c", "30")
+    batch.delete("b")
+    db.write(batch)
+    check(toSeq(db.iter()) == @[("a", "10"), ("c", "30")])
+
+  test "batch append":
+    let batch = newBatch()
+    let batch2 = newBatch()
+    batch.put("a", "1")
+    batch2.put("b", "2")
+    batch2.delete("a")
+    batch.append(batch2)
+    db.write(batch)
+    check(toSeq(db.iter()) == @[("b", "2")])
+
+  test "batch clear":
+    let batch = newBatch()
+    batch.put("a", "1")
+    batch.clear()
+    batch.put("b", "2")
+    db.write(batch)
+    check(toSeq(db.iter()) == @[("b", "2")])
+
+  test "open with cache":
+    let ldb = leveldb.open(dbName & "-cache", cacheCapacity = 100000)
+    ldb.put("a", "1")
+    check(toSeq(ldb.iter()) == @[("a", "1")])