From 594a5deb8396f8942899d0508ad8364a910c9a78 Mon Sep 17 00:00:00 2001
From: Xie Yanbo <xieyanbo@gmail.com>
Date: Sat, 14 Dec 2019 18:11:20 +0800
Subject: [PATCH 1/2] add batch procedure

---
 src/leveldb.nim | 30 ++++++++++++++++++++++++++++++
 tests/test.nim  | 28 ++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/src/leveldb.nim b/src/leveldb.nim
index 3567564..6ba9275 100644
--- a/src/leveldb.nim
+++ b/src/leveldb.nim
@@ -7,6 +7,9 @@ type
     asyncWriteOptions: ptr leveldb_writeoptions_t
     readOptions: ptr leveldb_readoptions_t
 
+  LevelDbBatch* = ref object
+    batch: ptr leveldb_writebatch_t
+
   LevelDbException* = object of Exception
 
 const
@@ -82,6 +85,33 @@ 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
diff --git a/tests/test.nim b/tests/test.nim
index 611d678..4e63032 100644
--- a/tests/test.nim
+++ b/tests/test.nim
@@ -76,3 +76,31 @@ 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")])

From ebc0544b8f6154fdbdf57fc68bda0ca9eb76dc13 Mon Sep 17 00:00:00 2001
From: Xie Yanbo <xieyanbo@gmail.com>
Date: Sat, 14 Dec 2019 18:11:56 +0800
Subject: [PATCH 2/2] support cache option

---
 src/leveldb.nim | 11 ++++++++++-
 tests/test.nim  |  5 +++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/leveldb.nim b/src/leveldb.nim
index 6ba9275..b51a657 100644
--- a/src/leveldb.nim
+++ b/src/leveldb.nim
@@ -6,6 +6,7 @@ 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
@@ -36,9 +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()
@@ -51,6 +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)
diff --git a/tests/test.nim b/tests/test.nim
index 4e63032..c1d79c6 100644
--- a/tests/test.nim
+++ b/tests/test.nim
@@ -104,3 +104,8 @@ suite "leveldb":
     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")])