diff --git a/include/libs/wal/wal.h b/include/libs/wal/wal.h
index b514648bbd..f84297670b 100644
--- a/include/libs/wal/wal.h
+++ b/include/libs/wal/wal.h
@@ -55,12 +55,14 @@ typedef struct {
   uint32_t signature;
   uint32_t cksumHead;
   uint32_t cksumBody;
-  //char     cont[];
+  char     cont[];
 } SWalHead;
 
 typedef struct {
   int32_t  vgId;
   int32_t  fsyncPeriod;  // millisecond
+  int32_t  rollPeriod;
+  int64_t  segSize;
   EWalType walLevel;     // wal level
 } SWalCfg;
 
@@ -87,36 +89,41 @@ typedef struct SWal {
   // cfg
   int32_t  vgId;
   int32_t  fsyncPeriod;  // millisecond
-  int32_t  fsyncSeq;
   int32_t  rollPeriod;  // second
   int64_t  segSize;
+  int64_t  retentionSize;
+  int32_t  retentionPeriod;
   EWalType level;
+  //total size
+  int64_t  totSize;
+  //fsync seq
+  int32_t  fsyncSeq;
   //reference
   int64_t refId;
-  //current tfd
-  int64_t curLogTfd;
-  int64_t curIdxTfd;
+  //write tfd
+  int64_t writeLogTfd;
+  int64_t writeIdxTfd;
+  //read tfd
+  int64_t readLogTfd;
+  int64_t readIdxTfd;
   //current version
   int64_t curVersion;
-  int64_t curLogOffset;
-  //current file version
-  int64_t curFileFirstVersion;
-  int64_t curFileLastVersion;
-  //wal fileset version
+  //wal lifecycle
   int64_t firstVersion;
   int64_t snapshotVersion;
+  int64_t commitVersion;
   int64_t lastVersion;
-  int64_t lastFileName;
   //roll status
   int64_t lastRollSeq;
-  int64_t lastFileWriteSize;
+  //file set
+  int32_t writeCur;
+  int32_t readCur;
+  SArray* fileInfoSet;
   //ctl
   int32_t curStatus;
   pthread_mutex_t mutex;
   //path
   char path[WAL_PATH_LEN];
-  //file set
-  SArray* fileSet;
   //reusable write head
   SWalHead head;
 } SWal;  // WAL HANDLE
@@ -133,7 +140,7 @@ int32_t walAlter(SWal *, SWalCfg *pCfg);
 void    walClose(SWal *);
 
 // write
-int64_t walWrite(SWal *, int64_t index, uint8_t msgType, void *body, int32_t bodyLen);
+int64_t walWrite(SWal *, int64_t index, uint8_t msgType, const void *body, int32_t bodyLen);
 void    walFsync(SWal *, bool force);
 
 // apis for lifecycle management
diff --git a/include/util/tarray.h b/include/util/tarray.h
index 5807c980e0..25862a7119 100644
--- a/include/util/tarray.h
+++ b/include/util/tarray.h
@@ -146,6 +146,13 @@ void* taosArrayInsert(SArray* pArray, size_t index, void* pData);
  */
 void taosArraySet(SArray* pArray, size_t index, void* pData);
 
+/**
+ * remove some data entry from front
+ * @param pArray
+ * @param cnt
+ */
+void taosArrayPopFrontBatch(SArray* pArray, size_t cnt);
+
 /**
  * remove data entry of the given index
  * @param pArray
diff --git a/include/util/tfile.h b/include/util/tfile.h
index 3d0e2177ac..af4c19e7d1 100644
--- a/include/util/tfile.h
+++ b/include/util/tfile.h
@@ -16,6 +16,8 @@
 #ifndef _TD_UTIL_FILE_H
 #define _TD_UTIL_FILE_H
 
+#include "os.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
diff --git a/include/util/tmd5.h b/include/util/tmd5.h
index 329f4acf11..f8114ad57b 100644
--- a/include/util/tmd5.h
+++ b/include/util/tmd5.h
@@ -30,10 +30,10 @@ typedef struct {
   uint32_t buf[4];     /* scratch buffer */
   uint8_t  in[64];     /* input buffer */
   uint8_t  digest[16]; /* actual digest after MD5Final call */
-} MD5_CTX;
+} T_MD5_CTX;
 
-void MD5Init(MD5_CTX *mdContext);
-void MD5Update(MD5_CTX *mdContext, uint8_t *inBuf, unsigned int inLen);
-void MD5Final(MD5_CTX *mdContext);
+void tMD5Init(T_MD5_CTX *mdContext);
+void tMD5Update(T_MD5_CTX *mdContext, uint8_t *inBuf, unsigned int inLen);
+void tMD5Final(T_MD5_CTX *mdContext);
 
 #endif /*_TD_UTIL_MD5_H*/
diff --git a/include/util/tutil.h b/include/util/tutil.h
index 41eb2ca26b..e4e66901d3 100644
--- a/include/util/tutil.h
+++ b/include/util/tutil.h
@@ -48,10 +48,10 @@ void     taosIpPort2String(uint32_t ip, uint16_t port, char *str);
 int32_t  taosGetFqdnPortFromEp(const char *ep, char *fqdn, uint16_t *port);
 
 static FORCE_INLINE void taosEncryptPass(uint8_t *inBuf, size_t inLen, char *target) {
-  MD5_CTX context;
-  MD5Init(&context);
-  MD5Update(&context, inBuf, (uint32_t)inLen);
-  MD5Final(&context);
+  T_MD5_CTX context;
+  tMD5Init(&context);
+  tMD5Update(&context, inBuf, (unsigned int)inLen);
+  tMD5Final(&context);
   memcpy(target, context.digest, TSDB_KEY_LEN);
 }
 
diff --git a/source/dnode/vnode/impl/test/vnodeApiTests.cpp b/source/dnode/vnode/impl/test/vnodeApiTests.cpp
index 493fe4448b..df784181b7 100644
--- a/source/dnode/vnode/impl/test/vnodeApiTests.cpp
+++ b/source/dnode/vnode/impl/test/vnodeApiTests.cpp
@@ -45,7 +45,7 @@ static SKVRow createBasicTag() {
 
   tdInitKVRowBuilder(&rb);
 
-  for (int i = 10; i < 12; i++) {
+  for (int i = 0; i < 2; i++) {
     void *pVal = malloc(sizeof(VarDataLenT) + strlen("foo"));
     varDataLen(pVal) = strlen("foo");
     memcpy(varDataVal(pVal), "foo", strlen("foo"));
@@ -120,7 +120,7 @@ TEST(vnodeApiTest, vnodeOpen_vnodeClose_test) {
 
   {
     // Create some child tables
-    int ntables = 100000;
+    int ntables = 1000000;
     int batch = 10;
     for (int i = 0; i < ntables / batch; i++) {
       SArray *pMsgs = (SArray *)taosArrayInit(batch, sizeof(SRpcMsg *));
diff --git a/source/dnode/vnode/meta/src/metaBDBImpl.c b/source/dnode/vnode/meta/src/metaBDBImpl.c
index 9e52a7151d..3c1ccc72dc 100644
--- a/source/dnode/vnode/meta/src/metaBDBImpl.c
+++ b/source/dnode/vnode/meta/src/metaBDBImpl.c
@@ -20,6 +20,11 @@
 #include "tcoding.h"
 #include "thash.h"
 
+typedef struct {
+  tb_uid_t uid;
+  int32_t  sver;
+} SSchemaKey;
+
 struct SMetaDB {
   // DB
   DB *pTbDB;
@@ -39,13 +44,17 @@ static SMetaDB *metaNewDB();
 static void     metaFreeDB(SMetaDB *pDB);
 static int      metaOpenBDBEnv(DB_ENV **ppEnv, const char *path);
 static void     metaCloseBDBEnv(DB_ENV *pEnv);
-static int      metaOpenBDBDb(DB **ppDB, DB_ENV *pEnv, const char *pFName);
+static int      metaOpenBDBDb(DB **ppDB, DB_ENV *pEnv, const char *pFName, bool isDup);
 static void     metaCloseBDBDb(DB *pDB);
-static int      metaOpenBDBIdx(DB **ppIdx, DB_ENV *pEnv, const char *pFName, DB *pDB, bdbIdxCbPtr cbf);
+static int      metaOpenBDBIdx(DB **ppIdx, DB_ENV *pEnv, const char *pFName, DB *pDB, bdbIdxCbPtr cbf, bool isDup);
+static void     metaCloseBDBIdx(DB *pIdx);
 static int      metaNameIdxCb(DB *pIdx, const DBT *pKey, const DBT *pValue, DBT *pSKey);
 static int      metaStbIdxCb(DB *pIdx, const DBT *pKey, const DBT *pValue, DBT *pSKey);
 static int      metaNtbIdxCb(DB *pIdx, const DBT *pKey, const DBT *pValue, DBT *pSKey);
 static int      metaCtbIdxCb(DB *pIdx, const DBT *pKey, const DBT *pValue, DBT *pSKey);
+static int      metaEncodeTbInfo(void **buf, STbCfg *pTbCfg);
+static void *   metaDecodeTbInfo(void *buf, STbCfg *pTbCfg);
+static void     metaClearTbCfg(STbCfg *pTbCfg);
 
 #define BDB_PERR(info, code) fprintf(stderr, info " reason: %s", db_strerror(code))
 
@@ -67,33 +76,33 @@ int metaOpenDB(SMeta *pMeta) {
   }
 
   // Open DBs
-  if (metaOpenBDBDb(&(pDB->pTbDB), pDB->pEvn, "meta.db") < 0) {
+  if (metaOpenBDBDb(&(pDB->pTbDB), pDB->pEvn, "meta.db", false) < 0) {
     metaCloseDB(pMeta);
     return -1;
   }
 
-  if (metaOpenBDBDb(&(pDB->pSchemaDB), pDB->pEvn, "meta.db") < 0) {
+  if (metaOpenBDBDb(&(pDB->pSchemaDB), pDB->pEvn, "meta.db", false) < 0) {
     metaCloseDB(pMeta);
     return -1;
   }
 
   // Open Indices
-  if (metaOpenBDBIdx(&(pDB->pNameIdx), pDB->pEvn, "index.db", pDB->pTbDB, &metaNameIdxCb) < 0) {
+  if (metaOpenBDBIdx(&(pDB->pNameIdx), pDB->pEvn, "name.index", pDB->pTbDB, &metaNameIdxCb, false) < 0) {
     metaCloseDB(pMeta);
     return -1;
   }
 
-  if (metaOpenBDBIdx(&(pDB->pStbIdx), pDB->pEvn, "index.db", pDB->pTbDB, &metaStbIdxCb) < 0) {
+  if (metaOpenBDBIdx(&(pDB->pStbIdx), pDB->pEvn, "stb.index", pDB->pTbDB, &metaStbIdxCb, false) < 0) {
     metaCloseDB(pMeta);
     return -1;
   }
 
-  if (metaOpenBDBIdx(&(pDB->pNtbIdx), pDB->pEvn, "index.db", pDB->pTbDB, &metaNtbIdxCb) < 0) {
+  if (metaOpenBDBIdx(&(pDB->pNtbIdx), pDB->pEvn, "ntb.index", pDB->pTbDB, &metaNtbIdxCb, false) < 0) {
     metaCloseDB(pMeta);
     return -1;
   }
 
-  if (metaOpenBDBIdx(&(pDB->pCtbIdx), pDB->pEvn, "index.db", pDB->pTbDB, &metaCtbIdxCb) < 0) {
+  if (metaOpenBDBIdx(&(pDB->pCtbIdx), pDB->pEvn, "ctb.index", pDB->pTbDB, &metaCtbIdxCb, true) < 0) {
     metaCloseDB(pMeta);
     return -1;
   }
@@ -103,6 +112,12 @@ int metaOpenDB(SMeta *pMeta) {
 
 void metaCloseDB(SMeta *pMeta) {
   if (pMeta->pDB) {
+    metaCloseBDBIdx(pMeta->pDB->pCtbIdx);
+    metaCloseBDBIdx(pMeta->pDB->pNtbIdx);
+    metaCloseBDBIdx(pMeta->pDB->pStbIdx);
+    metaCloseBDBIdx(pMeta->pDB->pNameIdx);
+    metaCloseBDBDb(pMeta->pDB->pSchemaDB);
+    metaCloseBDBDb(pMeta->pDB->pTbDB);
     metaCloseBDBEnv(pMeta->pDB->pEvn);
     metaFreeDB(pMeta->pDB);
     pMeta->pDB = NULL;
@@ -110,7 +125,60 @@ void metaCloseDB(SMeta *pMeta) {
 }
 
 int metaSaveTableToDB(SMeta *pMeta, STbCfg *pTbCfg) {
-  // TODO
+  tb_uid_t  uid;
+  char      buf[512];
+  void *    pBuf;
+  DBT       key, value;
+  STSchema *pSchema = NULL;
+
+  if (pTbCfg->type == META_SUPER_TABLE) {
+    uid = pTbCfg->stbCfg.suid;
+  } else {
+    uid = metaGenerateUid(pMeta);
+  }
+
+  {
+    // save table info
+    pBuf = buf;
+    memset(&key, 0, sizeof(key));
+    memset(&value, 0, sizeof(key));
+
+    key.data = &uid;
+    key.size = sizeof(uid);
+
+    metaEncodeTbInfo(&pBuf, pTbCfg);
+
+    value.data = buf;
+    value.size = POINTER_DISTANCE(pBuf, buf);
+    value.app_data = pTbCfg;
+
+    pMeta->pDB->pTbDB->put(pMeta->pDB->pTbDB, NULL, &key, &value, 0);
+  }
+
+  // save schema
+  if (pTbCfg->type == META_SUPER_TABLE) {
+    pSchema = pTbCfg->stbCfg.pSchema;
+  } else if (pTbCfg->type == META_NORMAL_TABLE) {
+    pSchema = pTbCfg->ntbCfg.pSchema;
+  }
+
+  if (pSchema) {
+    pBuf = buf;
+    memset(&key, 0, sizeof(key));
+    memset(&value, 0, sizeof(key));
+    SSchemaKey schemaKey = {uid, schemaVersion(pSchema)};
+
+    key.data = &schemaKey;
+    key.size = sizeof(schemaKey);
+
+    tdEncodeSchema(&pBuf, pSchema);
+
+    value.data = buf;
+    value.size = POINTER_DISTANCE(pBuf, buf);
+
+    pMeta->pDB->pSchemaDB->put(pMeta->pDB->pSchemaDB, NULL, &key, &value, 0);
+  }
+
   return 0;
 }
 
@@ -165,16 +233,24 @@ static void metaCloseBDBEnv(DB_ENV *pEnv) {
   }
 }
 
-static int metaOpenBDBDb(DB **ppDB, DB_ENV *pEnv, const char *pFName) {
+static int metaOpenBDBDb(DB **ppDB, DB_ENV *pEnv, const char *pFName, bool isDup) {
   int ret;
   DB *pDB;
 
-  ret = db_create(&((pDB)), (pEnv), 0);
+  ret = db_create(&(pDB), pEnv, 0);
   if (ret != 0) {
     BDB_PERR("Failed to create META DB", ret);
     return -1;
   }
 
+  if (isDup) {
+    ret = pDB->set_flags(pDB, DB_DUPSORT);
+    if (ret != 0) {
+      BDB_PERR("Failed to set DB flags", ret);
+      return -1;
+    }
+  }
+
   ret = pDB->open(pDB, NULL, pFName, NULL, DB_BTREE, DB_CREATE, 0);
   if (ret) {
     BDB_PERR("Failed to open META DB", ret);
@@ -192,11 +268,11 @@ static void metaCloseBDBDb(DB *pDB) {
   }
 }
 
-static int metaOpenBDBIdx(DB **ppIdx, DB_ENV *pEnv, const char *pFName, DB *pDB, bdbIdxCbPtr cbf) {
+static int metaOpenBDBIdx(DB **ppIdx, DB_ENV *pEnv, const char *pFName, DB *pDB, bdbIdxCbPtr cbf, bool isDup) {
   DB *pIdx;
   int ret;
 
-  if (metaOpenBDBDb(ppIdx, pEnv, pFName) < 0) {
+  if (metaOpenBDBDb(ppIdx, pEnv, pFName, isDup) < 0) {
     return -1;
   }
 
@@ -216,158 +292,70 @@ static void metaCloseBDBIdx(DB *pIdx) {
 }
 
 static int metaNameIdxCb(DB *pIdx, const DBT *pKey, const DBT *pValue, DBT *pSKey) {
-  // TODO
+  STbCfg *pTbCfg = (STbCfg *)(pValue->app_data);
+
+  memset(pSKey, 0, sizeof(*pSKey));
+
+  pSKey->data = pTbCfg->name;
+  pSKey->size = strlen(pTbCfg->name);
+
   return 0;
 }
 
 static int metaStbIdxCb(DB *pIdx, const DBT *pKey, const DBT *pValue, DBT *pSKey) {
-  // TODO
-  return 0;
+  STbCfg *pTbCfg = (STbCfg *)(pValue->app_data);
+
+  if (pTbCfg->type == META_SUPER_TABLE) {
+    memset(pSKey, 0, sizeof(*pSKey));
+    pSKey->data = pKey->data;
+    pSKey->size = pKey->size;
+
+    return 0;
+  } else {
+    return DB_DONOTINDEX;
+  }
 }
 
 static int metaNtbIdxCb(DB *pIdx, const DBT *pKey, const DBT *pValue, DBT *pSKey) {
-  // TODO
-  return 0;
+  STbCfg *pTbCfg = (STbCfg *)(pValue->app_data);
+
+  if (pTbCfg->type == META_NORMAL_TABLE) {
+    memset(pSKey, 0, sizeof(*pSKey));
+    pSKey->data = pKey->data;
+    pSKey->size = pKey->size;
+
+    return 0;
+  } else {
+    return DB_DONOTINDEX;
+  }
 }
 
 static int metaCtbIdxCb(DB *pIdx, const DBT *pKey, const DBT *pValue, DBT *pSKey) {
-  // TODO
-  return 0;
-}
+  STbCfg *pTbCfg = (STbCfg *)(pValue->app_data);
+  DBT *   pDbt;
 
-#if 0
-typedef struct {
-  tb_uid_t uid;
-  int32_t  sver;
-} SSchemaKey;
+  if (pTbCfg->type == META_CHILD_TABLE) {
+    pDbt = calloc(2, sizeof(DBT));
 
+    // First key is suid
+    pDbt[0].data = &(pTbCfg->ctbCfg.suid);
+    pDbt[0].size = sizeof(pTbCfg->ctbCfg.suid);
 
-static SMetaDB *metaNewDB();
-static void     metaFreeDB(SMetaDB *pDB);
-static int      metaCreateDBEnv(SMetaDB *pDB, const char *path);
-static void     metaDestroyDBEnv(SMetaDB *pDB);
-static int      metaEncodeSchemaKey(void **buf, SSchemaKey *pSchemaKey);
-static void *   metaDecodeSchemaKey(void *buf, SSchemaKey *pSchemaKey);
-static int      metaNameIdxCb(DB *sdbp, const DBT *pKey, const DBT *pValue, DBT *pSKey);
-static int      metaUidIdxCb(DB *sdbp, const DBT *pKey, const DBT *pValue, DBT *pSKey);
-static void     metaPutSchema(SMeta *pMeta, tb_uid_t uid, STSchema *pSchema);
-static int      metaEncodeTbInfo(void **buf, STbCfg *pTbCfg);
-static void *   metaDecodeTbInfo(void *buf, STbCfg *pTbCfg);
-static int      metaSaveTbInfo(DB *pDB, tb_uid_t uid, STbCfg *pTbCfg);
+    // Second key is the first tag
+    void *pTagVal = tdGetKVRowValOfCol(pTbCfg->ctbCfg.pTag, 0);
+    pDbt[1].data = varDataVal(pTagVal);
+    pDbt[1].size = varDataLen(pTagVal);
 
-#define META_ASSOCIATE_IDX(pDB, pIdx, cbf)                     \
-  do {                                                         \
-    int ret = (pDB)->associate((pDB), NULL, (pIdx), (cbf), 0); \
-    if (ret != 0) {                                            \
-      P_ERROR("Failed to associate META DB", ret);             \
-      metaCloseDB(pMeta);                                      \
-    }                                                          \
-  } while (0)
+    // Set index key
+    memset(pSKey, 0, sizeof(*pSKey));
+    pSKey->flags = DB_DBT_MULTIPLE | DB_DBT_APPMALLOC;
+    pSKey->data = pDbt;
+    pSKey->size = 2;
 
-
-int metaSaveTableToDB(SMeta *pMeta, STbCfg *pTbCfg) {
-  char       buf[512];
-  void *     pBuf;
-  DBT        key = {0};
-  DBT        value = {0};
-  SSchemaKey schemaKey;
-  tb_uid_t   uid;
-
-  if (pTbCfg->type == META_SUPER_TABLE) {
-    // Handle SUPER table
-    uid = pTbCfg->stbCfg.suid;
-
-    // Same table info
-    metaSaveTbInfo(pMeta->pDB->pStbDB, uid, pTbCfg);
-
-    // save schema
-    metaPutSchema(pMeta, uid, pTbCfg->stbCfg.pSchema);
-
-    {
-      // Create a super table DB and corresponding index DB
-      DB *pStbDB;
-      DB *pStbIdxDB;
-
-      META_OPEN_DB(pStbDB, pMeta->pDB->pEvn, "meta.db");
-
-      META_OPEN_DB(pStbIdxDB, pMeta->pDB->pEvn, "index.db");
-
-      // TODO META_ASSOCIATE_IDX();
-    }
-  } else if (pTbCfg->type == META_CHILD_TABLE) {
-    // Handle CHILD table
-    uid = metaGenerateUid(pMeta);
-
-    DB *pCTbDB = taosHashGet(pMeta->pDB->pCtbMap, &(pTbCfg->ctbCfg.suid), sizeof(pTbCfg->ctbCfg.suid));
-    if (pCTbDB == NULL) {
-      ASSERT(0);
-    }
-
-    metaSaveTbInfo(pCTbDB, uid, pTbCfg);
-
-  } else if (pTbCfg->type == META_NORMAL_TABLE) {
-    // Handle NORMAL table
-    uid = metaGenerateUid(pMeta);
-
-    metaSaveTbInfo(pMeta->pDB->pNtbDB, uid, pTbCfg);
-
-    metaPutSchema(pMeta, uid, pTbCfg->stbCfg.pSchema);
+    return 0;
   } else {
-    ASSERT(0);
+    return DB_DONOTINDEX;
   }
-
-  return 0;
-}
-
-int metaRemoveTableFromDb(SMeta *pMeta, tb_uid_t uid) {
-  // TODO
-}
-
-/* ------------------------ STATIC METHODS ------------------------ */
-static int metaEncodeSchemaKey(void **buf, SSchemaKey *pSchemaKey) {
-  int tsize = 0;
-
-  tsize += taosEncodeFixedU64(buf, pSchemaKey->uid);
-  tsize += taosEncodeFixedI32(buf, pSchemaKey->sver);
-
-  return tsize;
-}
-
-static void *metaDecodeSchemaKey(void *buf, SSchemaKey *pSchemaKey) {
-  buf = taosDecodeFixedU64(buf, &(pSchemaKey->uid));
-  buf = taosDecodeFixedI32(buf, &(pSchemaKey->sver));
-
-  return buf;
-}
-
-static int metaNameIdxCb(DB *sdbp, const DBT *pKey, const DBT *pValue, DBT *pSKey) {
-  // TODO
-  return 0;
-}
-
-static int metaUidIdxCb(DB *sdbp, const DBT *pKey, const DBT *pValue, DBT *pSKey) {
-  // TODO
-  return 0;
-}
-
-static void metaPutSchema(SMeta *pMeta, tb_uid_t uid, STSchema *pSchema) {
-  SSchemaKey skey;
-  char       buf[256];
-  void *     pBuf = buf;
-  DBT        key = {0};
-  DBT        value = {0};
-
-  skey.uid = uid;
-  skey.sver = schemaVersion(pSchema);
-
-  key.data = &skey;
-  key.size = sizeof(skey);
-
-  tdEncodeSchema(&pBuf, pSchema);
-  value.data = buf;
-  value.size = POINTER_DISTANCE(pBuf, buf);
-
-  pMeta->pDB->pSchemaDB->put(pMeta->pDB->pSchemaDB, NULL, &key, &value, 0);
 }
 
 static int metaEncodeTbInfo(void **buf, STbCfg *pTbCfg) {
@@ -376,6 +364,7 @@ static int metaEncodeTbInfo(void **buf, STbCfg *pTbCfg) {
   tsize += taosEncodeString(buf, pTbCfg->name);
   tsize += taosEncodeFixedU32(buf, pTbCfg->ttl);
   tsize += taosEncodeFixedU32(buf, pTbCfg->keep);
+  tsize += taosEncodeFixedU8(buf, pTbCfg->type);
 
   if (pTbCfg->type == META_SUPER_TABLE) {
     tsize += tdEncodeSchema(buf, pTbCfg->stbCfg.pTagSchema);
@@ -391,10 +380,10 @@ static int metaEncodeTbInfo(void **buf, STbCfg *pTbCfg) {
 }
 
 static void *metaDecodeTbInfo(void *buf, STbCfg *pTbCfg) {
-  // TODO
   buf = taosDecodeString(buf, &(pTbCfg->name));
   buf = taosDecodeFixedU32(buf, &(pTbCfg->ttl));
   buf = taosDecodeFixedU32(buf, &(pTbCfg->keep));
+  buf = taosDecodeFixedU8(buf, &(pTbCfg->type));
 
   if (pTbCfg->type == META_SUPER_TABLE) {
     buf = tdDecodeSchema(buf, &(pTbCfg->stbCfg.pTagSchema));
@@ -408,22 +397,11 @@ static void *metaDecodeTbInfo(void *buf, STbCfg *pTbCfg) {
   return buf;
 }
 
-static int metaSaveTbInfo(DB *pDB, tb_uid_t uid, STbCfg *pTbCfg) {
-  DBT   key = {0};
-  DBT   value = {0};
-  char  buf[512];
-  void *pBuf = buf;
-
-  key.data = &uid;
-  key.size = sizeof(uid);
-
-  metaEncodeTbInfo(&pBuf, pTbCfg);
-
-  value.data = buf;
-  value.size = POINTER_DISTANCE(pBuf, buf);
-
-  pDB->put(pDB, NULL, &key, &value, 0);
-
-  return 0;
-}
-#endif
\ No newline at end of file
+static void metaClearTbCfg(STbCfg *pTbCfg) {
+  tfree(pTbCfg->name);
+  if (pTbCfg->type == META_SUPER_TABLE) {
+    tdFreeSchema(pTbCfg->stbCfg.pTagSchema);
+  } else if (pTbCfg->type == META_CHILD_TABLE) {
+    tfree(pTbCfg->ctbCfg.pTag);
+  }
+}
\ No newline at end of file
diff --git a/source/libs/index/src/index_fst.c b/source/libs/index/src/index_fst.c
index 40e35306a2..403b4a9122 100644
--- a/source/libs/index/src/index_fst.c
+++ b/source/libs/index/src/index_fst.c
@@ -297,15 +297,16 @@ void fstStateCompileForAnyTrans(FstCountingWriter *w, CompiledAddr addr, FstBuil
     // any value greater than or equal to the number of transitions in
     // this node indicates an absent transition.
     uint8_t *index = (uint8_t *)malloc(sizeof(uint8_t) * 256); 
-    for (uint8_t i = 0; i < 256; i++) {
-      index[i] = 255;
-    }
+    memset(index, 255, sizeof(uint8_t) * 256);
+    ///for (uint8_t i = 0; i < 256; i++) {
+    //  index[i] = 255;
+    ///}
     for (size_t i = 0; i < sz; i++) {
       FstTransition *t = taosArrayGet(node->trans, i);
       index[t->inp] = i;
-      fstCountingWriterWrite(w, (char *)index, sizeof(index)); 
       //fstPackDeltaIn(w, addr, t->addr, tSize);
     }
+    fstCountingWriterWrite(w, (char *)index, 256); 
     free(index);
   }
   fstCountingWriterWrite(w, (char *)&packSizes, 1);
@@ -478,6 +479,7 @@ Output fstStateOutputForAnyTrans(FstState *s, FstNode *node, uint64_t i) {
     return 0;    
   }  
   FstSlice *slice = &node->data;
+  uint8_t *data = fstSliceData(slice, NULL);              
   uint64_t at = node->start
                 - fstStateNtransLen(s)
                 - 1 // pack size
@@ -485,7 +487,6 @@ Output fstStateOutputForAnyTrans(FstState *s, FstNode *node, uint64_t i) {
                 - (i * oSizes)
                 - oSizes;
 
-  uint8_t *data = fstSliceData(slice, NULL);              
   return unpackUint64(data + at, oSizes);
 }
 
@@ -555,6 +556,7 @@ Output  fstStateFinalOutput(FstState *s, uint64_t version, FstSlice *slice, Pack
    uint64_t at = FST_SLICE_LEN(slice) 
                  - 1 
                  - fstStateNtransLen(s)
+                 - 1 // pack size
                  - fstStateTotalTransSize(s, version, sizes, nTrans)
                  - (nTrans * oSizes)
                  - oSizes;
@@ -587,7 +589,8 @@ uint64_t fstStateFindInput(FstState *s, FstNode *node, uint8_t b, bool *null) {
     FstSlice t = fstSliceCopy(slice, start, end - 1);
     int32_t len = 0; 
     uint8_t *data = fstSliceData(&t, &len);
-    for(int i = 0; i < len; i++) {
+    int i = 0;
+    for(; i < len; i++) {
       //uint8_t v = slice->data[slice->start + i];
       ////slice->data[slice->start + i];
       uint8_t v = data[i]; 
@@ -595,6 +598,7 @@ uint64_t fstStateFindInput(FstState *s, FstNode *node, uint8_t b, bool *null) {
         return node->nTrans - i - 1; // bug  
       }
     } 
+    if (i == len) { *null = true; }
   } 
 }
 
@@ -774,7 +778,7 @@ FstBuilder *fstBuilderCreate(void *w, FstType ty) {
   if (NULL == b) { return b; }
 
    
-  b->wrt = fstCountingWriterCreate(w, false);
+  b->wrt        = fstCountingWriterCreate(w, false);
   b->unfinished = fstUnFinishedNodesCreate();   
   b->registry   = fstRegistryCreate(10000, 2) ;
   b->last       = fstSliceCreate(NULL, 0);
@@ -857,6 +861,7 @@ OrderType fstBuilderCheckLastKey(FstBuilder *b, FstSlice bs, bool ckDup) {
       return OutOfOrdered;
     }
     // deep copy or not
+    fstSliceDestroy(&b->last);
     b->last = fstSliceCopy(&bs, input->start, input->end); 
   }       
   return Ordered;
@@ -1007,8 +1012,7 @@ Fst* fstCreate(FstSlice *slice) {
   uint64_t fstLen; 
   len -= sizeof(fstLen); 
   taosDecodeFixedU64(buf + len, &fstLen);
-  //TODO(validat root addr)
-  // 
+  //TODO(validate root addr)
   Fst *fst= (Fst *)calloc(1, sizeof(Fst)); 
   if (fst == NULL) { return NULL; }  
   
@@ -1023,6 +1027,7 @@ Fst* fstCreate(FstSlice *slice) {
   fst->meta->len      = fstLen;
   fst->meta->checkSum = checkSum;
   fst->data = slice; 
+  
   return fst;
 
 FST_CREAT_FAILED: 
@@ -1122,6 +1127,7 @@ FstBoundWithData* fstBoundStateCreate(FstBound type, FstSlice *data) {
   return b; 
 }
 
+
 bool fstBoundWithDataExceededBy(FstBoundWithData *bound, FstSlice *slice) {
   int comp = fstSliceCompare(slice, &bound->data);
   if (bound->type == Included) {
@@ -1374,7 +1380,9 @@ FstStreamBuilder *fstStreamBuilderCreate(Fst *fst, Automation *aut) {
 }
 void fstStreamBuilderDestroy(FstStreamBuilder *b) {
   fstSliceDestroy(&b->min->data);
+  tfree(b->min);  
   fstSliceDestroy(&b->max->data);
+  tfree(b->max);
   free(b);
 }
 FstStreamBuilder *fstStreamBuilderRange(FstStreamBuilder *b, FstSlice *val, RangeType type) {
diff --git a/source/libs/index/test/indexTests.cpp b/source/libs/index/test/indexTests.cpp
index 9135a7a173..928c3875b0 100644
--- a/source/libs/index/test/indexTests.cpp
+++ b/source/libs/index/test/indexTests.cpp
@@ -2,13 +2,79 @@
 #include <string>
 #include <iostream>
 #include "index.h"
+#include "tutil.h"
 #include "indexInt.h"
 #include "index_fst.h"
 #include "index_fst_util.h"
 #include "index_fst_counting_writer.h"
 
 
+class FstWriter {
+  public:
+    FstWriter() {
+      _b = fstBuilderCreate(NULL, 0);
+    }  
+   bool Put(const std::string &key, uint64_t val) {
+      FstSlice skey = fstSliceCreate((uint8_t *)key.c_str(), key.size());   
+      bool ok = fstBuilderInsert(_b, skey, val);
+      fstSliceDestroy(&skey);
+      return ok;
+   }
+   ~FstWriter() {
+     fstBuilderFinish(_b);
+     fstBuilderDestroy(_b);
+   }
+  private:
+    FstBuilder *_b; 
+};
 
+class FstReadMemory {
+  public:
+   FstReadMemory(size_t size) {
+     _w    = fstCountingWriterCreate(NULL, true); 
+     _size = size; 
+     memset((void *)&_s, 0, sizeof(_s));
+   }
+   bool init() {
+     char *buf = (char *)calloc(1,  sizeof(char) * _size);
+     int nRead = fstCountingWriterRead(_w, (uint8_t *)buf, _size); 
+     if (nRead <= 0) { return false; } 
+      _size = nRead;
+     _s   = fstSliceCreate((uint8_t *)buf, _size);  
+     _fst = fstCreate(&_s); 
+     free(buf);
+     return _fst != NULL;
+   }
+   bool Get(const std::string &key, uint64_t *val) {
+     FstSlice skey = fstSliceCreate((uint8_t *)key.c_str(), key.size());   
+     bool ok = fstGet(_fst, &skey, val); 
+     fstSliceDestroy(&skey);
+     return ok;
+   }
+   bool GetWithTimeCostUs(const std::string &key, uint64_t *val, uint64_t *elapse) {
+     int64_t s = taosGetTimestampUs();
+     bool ok = this->Get(key, val); 
+     int64_t e = taosGetTimestampUs();
+     *elapse = e - s;
+     return ok; 
+   }
+   // add later
+   bool Search(const std::string &key, std::vector<uint64_t> &result) {
+      return true;
+   }
+    
+   ~FstReadMemory() {
+    fstCountingWriterDestroy(_w);
+    fstSliceDestroy(&_s);
+  } 
+  
+  private:
+   FstCountingWriter *_w; 
+   Fst *_fst;
+   FstSlice _s;  
+   size_t _size;
+   
+}; 
 
 //TEST(IndexTest, index_create_test) {
 //  SIndexOpts *opts = indexOptsCreate();
@@ -62,69 +128,104 @@
 //  //
 //}
 
-int main(int argc, char** argv) {
-  // test write
-  FstBuilder *b = fstBuilderCreate(NULL, 0);
-  {
-    std::string str("aaa");
-    FstSlice key = fstSliceCreate((uint8_t *)str.c_str(), str.size());
-    Output   val = 1;
-    fstBuilderInsert(b, key, val); 
+
+
+int Performance_fstWriteRecords(FstWriter *b) {
+  std::string str("aa"); 
+  int L = 100, M = 100, N = 10;
+  for (int i = 0; i < L; i++) {
+    str[0] = 'a' + i;
+    str.resize(2); 
+    for(int j = 0; j < M; j++) {
+      str[1] = 'a' + j;
+      str.resize(2);
+      for (int k = 0; k < N; k++) {
+        str.push_back('a');
+        b->Put(str, k);
+        printf("(%d, %d, %d, %s)\n", i, j, k, str.c_str());
+      }
+    } 
   }
+  return L * M * N;
+}
 
-  //std::string str1("bcd");
-  //FstSlice key1 = fstSliceCreate((uint8_t *)str1.c_str(), str1.size());
-  //Output   val2 = 10;
-  //
-   
-  {
-     
-    for (size_t i = 1; i < 26; i++) {
-      std::string str("aaa");
-      str[2] = 'a' + i ;
-      FstSlice key = fstSliceCreate((uint8_t *)str.c_str(), str.size());
-      Output   val = 0;
-      fstBuilderInsert(b, key, val); 
-    }
-    
-  } 
-  fstBuilderFinish(b);
-  fstBuilderDestroy(b);
+void Performance_fstReadRecords(FstReadMemory *m) {
+   std::string str("a");
+   for (int i = 0; i < 50; i++) {
+     //std::string str("aa"); 
+     str.push_back('a');
+     uint64_t out, cost;
+     bool ok = m->GetWithTimeCostUs(str, &out, &cost); 
+     if (ok == true) {
+      printf("success to get (%s, %" PRId64"), time cost: %" PRId64")\n", str.c_str(), out, cost);
+     } else {
+      printf("failed to get(%s)\n", str.c_str());
+     }
+   }
+}
+void checkFstPerf() {
+  FstWriter *fw = new FstWriter;
+  int64_t s = taosGetTimestampUs();
+  int num = Performance_fstWriteRecords(fw);
+  int64_t e = taosGetTimestampUs();
+  printf("write %d record cost %" PRId64"us\n", num,  e - s);
+  delete fw;
 
-
-  char buf[64 * 1024] = {0};     
-
-  FstSlice s; 
-
-  FstCountingWriter *w = fstCountingWriterCreate(NULL, true);
-  int nRead = fstCountingWriterRead(w, (uint8_t *)buf, sizeof(buf)); 
-  assert(nRead <= sizeof(buf));  
-  s = fstSliceCreate((uint8_t *)buf, nRead);
-  fstCountingWriterDestroy(w);
-
-
-  // test reader
-  
-      
-  Fst *fst = fstCreate(&s); 
-  {
-    std::string str("aax"); 
-    uint64_t out;
-    
-       
-    FstSlice key = fstSliceCreate((uint8_t *)str.c_str(), str.size());
-    bool ok = fstGet(fst, &key, &out); 
-    if (ok == true) {
-      printf("val = %d\n", out);
-      //indexInfo("Get key-value success, %s, %d", str.c_str(), out); 
+  FstReadMemory *m = new FstReadMemory(1024 * 64);
+  if (m->init()) {
+    uint64_t val;
+    if(m->Get("aaaaaaa", &val)) {
+      std::cout << "succes to Get val: " << val << std::endl;
     } else {
-      //indexError("Get key-value failed, %s", str.c_str()); 
+      std::cout << "failed to Get " << std::endl;
+    } 
+  }  
+} 
+
+
+void validateFst() {
+  int val = 100;
+  int count = 100;
+  FstWriter *fw = new FstWriter;
+  // write 
+  {
+    std::string key("ab");
+    for (int i = 0; i < count; i++) {
+      key.push_back('a' + i);
+      fw->Put(key, val - i);
     }
   }
-  fstSliceDestroy(&s);
-  
+  delete fw;
 
-  
+  // read
+  FstReadMemory *m = new FstReadMemory(1024 * 64);
+  if (m->init() == false) { 
+    std::cout << "init readMemory failed" << std::endl; 
+  }
+
+  {
+   std::string key("ab");
+   uint64_t out;
+   if (m->Get(key, &out)) {
+     printf("success to get (%s, %" PRId64")\n", key.c_str(), out);
+   } else {
+     printf("failed to get(%s)\n", key.c_str());
+   }
+   for (int i = 0; i < count; i++) {
+     key.push_back('a' + i);
+     if (m->Get(key, &out) ) {
+       assert(val - i ==  out);
+       printf("success to get (%s, %" PRId64")\n", key.c_str(), out);
+     } else {
+       printf("failed to get(%s)\n", key.c_str());
+    }
+   }
+  } 
+  delete m;
+
+} 
+int main(int argc, char** argv) {
+  checkFstPerf(); 
   return 1;
 }
 
diff --git a/source/libs/transport/src/rpcMain.c b/source/libs/transport/src/rpcMain.c
index e392351366..911e8472ab 100644
--- a/source/libs/transport/src/rpcMain.c
+++ b/source/libs/transport/src/rpcMain.c
@@ -1523,14 +1523,14 @@ static SRpcHead *rpcDecompressRpcMsg(SRpcHead *pHead) {
 }
 
 static int rpcAuthenticateMsg(void *pMsg, int msgLen, void *pAuth, void *pKey) {
-  MD5_CTX context;
+  T_MD5_CTX context;
   int     ret = -1;
 
-  MD5Init(&context);
-  MD5Update(&context, (uint8_t *)pKey, TSDB_KEY_LEN);
-  MD5Update(&context, (uint8_t *)pMsg, msgLen);
-  MD5Update(&context, (uint8_t *)pKey, TSDB_KEY_LEN);
-  MD5Final(&context);
+  tMD5Init(&context);
+  tMD5Update(&context, (uint8_t *)pKey, TSDB_KEY_LEN);
+  tMD5Update(&context, (uint8_t *)pMsg, msgLen);
+  tMD5Update(&context, (uint8_t *)pKey, TSDB_KEY_LEN);
+  tMD5Final(&context);
 
   if (memcmp(context.digest, pAuth, sizeof(context.digest)) == 0) ret = 0;
 
@@ -1538,13 +1538,13 @@ static int rpcAuthenticateMsg(void *pMsg, int msgLen, void *pAuth, void *pKey) {
 }
 
 static void rpcBuildAuthHead(void *pMsg, int msgLen, void *pAuth, void *pKey) {
-  MD5_CTX context;
+  T_MD5_CTX context;
 
-  MD5Init(&context);
-  MD5Update(&context, (uint8_t *)pKey, TSDB_KEY_LEN);
-  MD5Update(&context, (uint8_t *)pMsg, msgLen);
-  MD5Update(&context, (uint8_t *)pKey, TSDB_KEY_LEN);
-  MD5Final(&context);
+  tMD5Init(&context);
+  tMD5Update(&context, (uint8_t *)pKey, TSDB_KEY_LEN);
+  tMD5Update(&context, (uint8_t *)pMsg, msgLen);
+  tMD5Update(&context, (uint8_t *)pKey, TSDB_KEY_LEN);
+  tMD5Final(&context);
 
   memcpy(pAuth, context.digest, sizeof(context.digest));
 }
diff --git a/source/libs/wal/CMakeLists.txt b/source/libs/wal/CMakeLists.txt
index e5697415f1..4d2dd97c87 100644
--- a/source/libs/wal/CMakeLists.txt
+++ b/source/libs/wal/CMakeLists.txt
@@ -8,6 +8,11 @@ target_include_directories(
 
 target_link_libraries(
     wal
+    PUBLIC cjson
     PUBLIC os
     PUBLIC util
 )
+
+if(${BUILD_TEST})
+    add_subdirectory(test)
+endif(${BUILD_TEST})
diff --git a/source/libs/wal/inc/walInt.h b/source/libs/wal/inc/walInt.h
index 285d7e2576..f56f240904 100644
--- a/source/libs/wal/inc/walInt.h
+++ b/source/libs/wal/inc/walInt.h
@@ -23,9 +23,73 @@
 extern "C" {
 #endif
 
-int walGetFile(SWal* pWal, int32_t version);
+//meta section begin
+typedef struct WalFileInfo {
+  int64_t firstVer;
+  int64_t lastVer;
+  int64_t createTs;
+  int64_t closeTs;
+  int64_t fileSize;
+} WalFileInfo;
+
+static inline int32_t compareWalFileInfo(const void* pLeft, const void* pRight) {
+  WalFileInfo* pInfoLeft = (WalFileInfo*)pLeft;
+  WalFileInfo* pInfoRight = (WalFileInfo*)pRight;
+  return compareInt64Val(&pInfoLeft->firstVer, &pInfoRight->firstVer);
+}
+
+static inline int64_t walGetLastFileSize(SWal* pWal) {
+  WalFileInfo* pInfo = (WalFileInfo*)taosArrayGetLast(pWal->fileInfoSet);
+  return pInfo->fileSize;
+}
+
+static inline int64_t walGetLastFileFirstVer(SWal* pWal) {
+  WalFileInfo* pInfo = (WalFileInfo*)taosArrayGetLast(pWal->fileInfoSet);
+  return pInfo->firstVer;
+}
+
+static inline int64_t walGetCurFileFirstVer(SWal* pWal) {
+  WalFileInfo* pInfo = (WalFileInfo*)taosArrayGet(pWal->fileInfoSet, pWal->writeCur);
+  return pInfo->firstVer;
+}
+
+static inline int64_t walGetCurFileLastVer(SWal* pWal) {
+  WalFileInfo* pInfo = (WalFileInfo*)taosArrayGet(pWal->fileInfoSet, pWal->writeCur);
+  return pInfo->firstVer;
+}
+
+static inline int64_t walGetCurFileOffset(SWal* pWal) {
+  WalFileInfo* pInfo = (WalFileInfo*)taosArrayGet(pWal->fileInfoSet, pWal->writeCur);
+  return pInfo->fileSize;
+}
+
+static inline bool walCurFileClosed(SWal* pWal) {
+  return taosArrayGetSize(pWal->fileInfoSet) != pWal->writeCur;
+}
+
+static inline WalFileInfo* walGetCurFileInfo(SWal* pWal) {
+  return (WalFileInfo*)taosArrayGet(pWal->fileInfoSet, pWal->writeCur);
+}
+
+static inline int walBuildLogName(SWal*pWal, int64_t fileFirstVer, char* buf) {
+  return sprintf(buf, "%s/%" PRId64 "." WAL_LOG_SUFFIX, pWal->path, fileFirstVer);
+}
+
+static inline int walBuildIdxName(SWal*pWal, int64_t fileFirstVer, char* buf) {
+  return sprintf(buf, "%s/%" PRId64 "." WAL_INDEX_SUFFIX, pWal->path, fileFirstVer);
+}
+
+int walReadMeta(SWal* pWal);
+int walWriteMeta(SWal* pWal);
+int walRollFileInfo(SWal* pWal);
+
+char* walMetaSerialize(SWal* pWal);
+int walMetaDeserialize(SWal* pWal, const char* bytes);
+//meta section end
 
 int64_t walGetSeq();
+int walSeekVer(SWal *pWal, int64_t ver);
+int walRoll(SWal *pWal);
 
 #ifdef __cplusplus
 }
diff --git a/source/libs/wal/src/walIndex.c b/source/libs/wal/src/walIndex.c
index 1aa64b34b5..bf51be4346 100644
--- a/source/libs/wal/src/walIndex.c
+++ b/source/libs/wal/src/walIndex.c
@@ -23,27 +23,27 @@
 static int walSeekFilePos(SWal* pWal, int64_t ver) {
   int code = 0;
 
-  int64_t idxTfd = pWal->curIdxTfd;
-  int64_t logTfd = pWal->curLogTfd;
+  int64_t idxTfd = pWal->writeIdxTfd;
+  int64_t logTfd = pWal->writeLogTfd;
   
   //seek position
-  int64_t offset = (ver - pWal->curFileFirstVersion) * WAL_IDX_ENTRY_SIZE;
+  int64_t offset = (ver - walGetCurFileFirstVer(pWal)) * WAL_IDX_ENTRY_SIZE;
   code = tfLseek(idxTfd, offset, SEEK_SET);
   if(code != 0) {
-
+    return -1;
   }
   int64_t readBuf[2];
   code = tfRead(idxTfd, readBuf, sizeof(readBuf));
   if(code != 0) {
-
+    return -1;
   }
   //TODO:deserialize
   ASSERT(readBuf[0] == ver);
   code = tfLseek(logTfd, readBuf[1], SEEK_CUR);
   if (code != 0) {
-
+    return -1;
   }
-  pWal->curLogOffset = readBuf[1];
+  /*pWal->curLogOffset = readBuf[1];*/
   pWal->curVersion = ver;
   return code;
 }
@@ -52,43 +52,43 @@ static int walChangeFile(SWal *pWal, int64_t ver) {
   int code = 0;
   int64_t idxTfd, logTfd;
   char fnameStr[WAL_FILE_LEN];
-  code = tfClose(pWal->curLogTfd);
+  code = tfClose(pWal->writeLogTfd);
   if(code != 0) {
    //TODO 
   }
-  code = tfClose(pWal->curIdxTfd);
+  code = tfClose(pWal->writeIdxTfd);
   if(code != 0) {
    //TODO 
   }
+  WalFileInfo tmpInfo;
+  tmpInfo.firstVer = ver;
   //bsearch in fileSet
-  int64_t* pRet = taosArraySearch(pWal->fileSet, &ver, compareInt64Val, TD_LE);
+  WalFileInfo* pRet = taosArraySearch(pWal->fileInfoSet, &tmpInfo, compareWalFileInfo, TD_LE);
   ASSERT(pRet != NULL);
-  int64_t fname = *pRet;
-  if(fname < pWal->lastFileName) {
+  int64_t fileFirstVer = pRet->firstVer;
+  //closed
+  if(taosArrayGetLast(pWal->fileInfoSet) != pRet) {
     pWal->curStatus &= ~WAL_CUR_FILE_WRITABLE;
-    pWal->curFileLastVersion = pRet[1]-1;
-    sprintf(fnameStr, "%"PRId64"."WAL_INDEX_SUFFIX, fname);
+    walBuildIdxName(pWal, fileFirstVer, fnameStr);
     idxTfd = tfOpenRead(fnameStr);
-    sprintf(fnameStr, "%"PRId64"."WAL_LOG_SUFFIX, fname);
+    walBuildLogName(pWal, fileFirstVer, fnameStr);
     logTfd = tfOpenRead(fnameStr);
   } else {
     pWal->curStatus |= WAL_CUR_FILE_WRITABLE;
-    pWal->curFileLastVersion = -1;
-    sprintf(fnameStr, "%"PRId64"."WAL_INDEX_SUFFIX, fname);
+    walBuildIdxName(pWal, fileFirstVer, fnameStr);
     idxTfd = tfOpenReadWrite(fnameStr);
-    sprintf(fnameStr, "%"PRId64"."WAL_LOG_SUFFIX, fname);
+    walBuildLogName(pWal, fileFirstVer, fnameStr);
     logTfd = tfOpenReadWrite(fnameStr);
   }
 
-  pWal->curFileFirstVersion = fname;
-  pWal->curLogTfd = logTfd;
-  pWal->curIdxTfd = idxTfd;
+  pWal->writeLogTfd = logTfd;
+  pWal->writeIdxTfd = idxTfd;
   return code;
 }
 
 int walSeekVer(SWal *pWal, int64_t ver) {
-  if((!(pWal->curStatus & WAL_CUR_FAILED))
-      && ver == pWal->curVersion) {
+  int code;
+  if((!(pWal->curStatus & WAL_CUR_FAILED)) && ver == pWal->curVersion) {
     return 0;
   }
   if(ver > pWal->lastVersion) {
@@ -102,11 +102,16 @@ int walSeekVer(SWal *pWal, int64_t ver) {
   if(ver < pWal->snapshotVersion) {
     //TODO: seek snapshotted log, invalid in some cases
   }
-  if(ver < pWal->curFileFirstVersion ||
-     (pWal->curFileLastVersion != -1 && ver > pWal->curFileLastVersion)) {
-    walChangeFile(pWal, ver);
+  if(ver < walGetCurFileFirstVer(pWal) || (ver > walGetCurFileLastVer(pWal))) {
+    code = walChangeFile(pWal, ver);
+    if(code != 0) {
+      return -1;
+    }
   }
-  walSeekFilePos(pWal, ver);
-  
+  code = walSeekFilePos(pWal, ver);
+  if(code != 0) {
+    return -1;
+  }
+   
   return 0;
 }
diff --git a/source/libs/wal/src/walMeta.c b/source/libs/wal/src/walMeta.c
new file mode 100644
index 0000000000..65085bb96d
--- /dev/null
+++ b/source/libs/wal/src/walMeta.c
@@ -0,0 +1,219 @@
+/*
+ * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
+ *
+ * This program is free software: you can use, redistribute, and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3
+ * or later ("AGPL"), as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#define _DEFAULT_SOURCE
+#include "os.h"
+#include "taoserror.h"
+#include "tref.h"
+#include "tfile.h"
+#include "cJSON.h"
+#include "walInt.h"
+
+#include <libgen.h>
+#include <regex.h>
+
+int walRollFileInfo(SWal* pWal) {
+  int64_t ts = taosGetTimestampSec();
+
+  SArray* pArray = pWal->fileInfoSet;
+  if(taosArrayGetSize(pArray) != 0) {
+    WalFileInfo *pInfo = taosArrayGetLast(pArray);
+    pInfo->lastVer = pWal->lastVersion;
+    pInfo->closeTs = ts;
+  }
+
+  WalFileInfo *pNewInfo = malloc(sizeof(WalFileInfo));
+  if(pNewInfo == NULL) {
+    return -1;
+  }
+  pNewInfo->firstVer = pWal->lastVersion + 1;
+  pNewInfo->lastVer = -1;
+  pNewInfo->createTs = ts;
+  pNewInfo->closeTs = -1;
+  pNewInfo->fileSize = 0;
+  taosArrayPush(pWal->fileInfoSet, pNewInfo);
+  return 0;
+}
+
+char* walMetaSerialize(SWal* pWal) {
+  char buf[30];
+  if(pWal == NULL || pWal->fileInfoSet == NULL) return 0;
+  int sz = pWal->fileInfoSet->size;
+  cJSON* pRoot = cJSON_CreateObject();
+  cJSON* pMeta = cJSON_CreateObject();
+  cJSON* pFiles = cJSON_CreateArray();
+  cJSON* pField;
+  if(pRoot == NULL || pMeta == NULL || pFiles == NULL) {
+    //TODO
+    return NULL;
+  }
+  cJSON_AddItemToObject(pRoot, "meta", pMeta);
+  sprintf(buf, "%" PRId64, pWal->firstVersion);
+  cJSON_AddStringToObject(pMeta, "firstVer", buf);
+  sprintf(buf, "%" PRId64, pWal->snapshotVersion);
+  cJSON_AddStringToObject(pMeta, "snapshotVer", buf);
+  sprintf(buf, "%" PRId64, pWal->commitVersion);
+  cJSON_AddStringToObject(pMeta, "commitVer", buf);
+  sprintf(buf, "%" PRId64, pWal->lastVersion);
+  cJSON_AddStringToObject(pMeta, "lastVer", buf);
+
+  cJSON_AddItemToObject(pRoot, "files", pFiles);
+  WalFileInfo* pData = pWal->fileInfoSet->pData;
+  for(int i = 0; i < sz; i++) {
+    WalFileInfo* pInfo = &pData[i];
+    cJSON_AddItemToArray(pFiles, pField = cJSON_CreateObject());
+    if(pField == NULL) {
+      cJSON_Delete(pRoot);
+      return NULL;
+    }
+    //cjson only support int32_t or double
+    //string are used to prohibit the loss of precision
+    sprintf(buf, "%" PRId64, pInfo->firstVer);
+    cJSON_AddStringToObject(pField, "firstVer", buf);
+    sprintf(buf, "%" PRId64, pInfo->lastVer);
+    cJSON_AddStringToObject(pField, "lastVer", buf);
+    sprintf(buf, "%" PRId64, pInfo->createTs);
+    cJSON_AddStringToObject(pField, "createTs", buf);
+    sprintf(buf, "%" PRId64, pInfo->closeTs);
+    cJSON_AddStringToObject(pField, "closeTs", buf);
+    sprintf(buf, "%" PRId64, pInfo->fileSize);
+    cJSON_AddStringToObject(pField, "fileSize", buf);
+  }
+  return cJSON_Print(pRoot);
+}
+
+int walMetaDeserialize(SWal* pWal, const char* bytes) {
+  ASSERT(taosArrayGetSize(pWal->fileInfoSet) == 0);
+  cJSON *pRoot, *pMeta, *pFiles, *pInfoJson, *pField;
+  pRoot = cJSON_Parse(bytes);
+  pMeta = cJSON_GetObjectItem(pRoot, "meta");
+  pField = cJSON_GetObjectItem(pMeta, "firstVer");
+  pWal->firstVersion = atoll(cJSON_GetStringValue(pField));
+  pField = cJSON_GetObjectItem(pMeta, "snapshotVer");
+  pWal->snapshotVersion = atoll(cJSON_GetStringValue(pField));
+  pField = cJSON_GetObjectItem(pMeta, "commitVer");
+  pWal->commitVersion = atoll(cJSON_GetStringValue(pField));
+  pField = cJSON_GetObjectItem(pMeta, "lastVer");
+  pWal->lastVersion = atoll(cJSON_GetStringValue(pField));
+
+  pFiles = cJSON_GetObjectItem(pRoot, "files");
+  int sz = cJSON_GetArraySize(pFiles);
+  //deserialize
+  SArray* pArray = taosArrayInit(sz, sizeof(WalFileInfo));
+  WalFileInfo *pData = pArray->pData;
+  for(int i = 0; i < sz; i++) {
+    cJSON* pInfoJson = cJSON_GetArrayItem(pFiles, i);
+    WalFileInfo* pInfo = &pData[i];
+    pField = cJSON_GetObjectItem(pInfoJson, "firstVer");
+    pInfo->firstVer = atoll(cJSON_GetStringValue(pField));
+    pField = cJSON_GetObjectItem(pInfoJson, "lastVer");
+    pInfo->lastVer = atoll(cJSON_GetStringValue(pField));
+    pField = cJSON_GetObjectItem(pInfoJson, "createTs");
+    pInfo->createTs = atoll(cJSON_GetStringValue(pField));
+    pField = cJSON_GetObjectItem(pInfoJson, "closeTs");
+    pInfo->closeTs = atoll(cJSON_GetStringValue(pField));
+    pField = cJSON_GetObjectItem(pInfoJson, "fileSize");
+    pInfo->fileSize = atoll(cJSON_GetStringValue(pField));
+  }
+  taosArraySetSize(pArray, sz);
+  pWal->fileInfoSet = pArray;
+  return 0;
+}
+
+static inline int walBuildMetaName(SWal* pWal, int metaVer, char* buf) {
+  return sprintf(buf, "%s/meta-ver%d", pWal->path, metaVer);
+}
+
+static int walFindCurMetaVer(SWal* pWal) {
+  const char * pattern = "^meta-ver[0-9]+$";
+  regex_t walMetaRegexPattern;
+  regcomp(&walMetaRegexPattern, pattern, REG_EXTENDED);
+
+  DIR *dir = opendir(pWal->path); 
+  if(dir == NULL) {
+    wError("vgId:%d, path:%s, failed to open since %s", pWal->vgId, pWal->path, strerror(errno));
+    return -1;
+  }
+
+  struct dirent* ent;
+
+  //find existing meta-ver[x].json
+  int metaVer = -1;
+  while((ent = readdir(dir)) != NULL) {
+    char *name = basename(ent->d_name);
+    int code = regexec(&walMetaRegexPattern, name, 0, NULL, 0);
+    if(code == 0) {
+      sscanf(name, "meta-ver%d", &metaVer);
+      break;
+    }
+  }
+  return metaVer;
+}
+
+int walWriteMeta(SWal* pWal) {
+  int metaVer = walFindCurMetaVer(pWal);
+  char fnameStr[WAL_FILE_LEN];
+  walBuildMetaName(pWal, metaVer+1, fnameStr);
+  int metaTfd = tfOpenCreateWrite(fnameStr);
+  if(metaTfd < 0) {
+    return -1;
+  }
+  char* serialized = walMetaSerialize(pWal);
+  int len = strlen(serialized);
+  if(len != tfWrite(metaTfd, serialized, len)) {
+    //TODO:clean file
+    return -1;
+  }
+  
+  tfClose(metaTfd);
+  //delete old file
+  if(metaVer > -1) {
+    walBuildMetaName(pWal, metaVer, fnameStr);
+    remove(fnameStr);
+  }
+  return 0;
+}
+
+int walReadMeta(SWal* pWal) {
+  ASSERT(pWal->fileInfoSet->size == 0);
+  //find existing meta file
+  int metaVer = walFindCurMetaVer(pWal);
+  if(metaVer == -1) {
+    return 0;
+  }
+  char fnameStr[WAL_FILE_LEN];
+  walBuildMetaName(pWal, metaVer, fnameStr);
+  //read metafile
+  struct stat statbuf;
+  stat(fnameStr, &statbuf);
+  int size = statbuf.st_size;
+  char* buf = malloc(size + 5);
+  if(buf == NULL) {
+    return -1;
+  }
+  int tfd = tfOpenRead(fnameStr);
+  if(tfRead(tfd, buf, size) != size) {
+    free(buf);
+    return -1;
+  }
+  //load into fileInfoSet
+  int code = walMetaDeserialize(pWal, buf);
+  if(code != 0) {
+    free(buf);
+    return -1;
+  }
+  free(buf);
+  return 0;
+}
diff --git a/source/libs/wal/src/walMgmt.c b/source/libs/wal/src/walMgmt.c
index bc2e687069..6bf9008917 100644
--- a/source/libs/wal/src/walMgmt.c
+++ b/source/libs/wal/src/walMgmt.c
@@ -48,9 +48,15 @@ int32_t walInit() {
   int8_t old = atomic_val_compare_exchange_8(&tsWal.inited, 0, 1);
   if(old == 1) return 0;
 
+  int code = tfInit();
+  if(code != 0) {
+    wError("failed to init tfile since %s", tstrerror(code));
+    atomic_store_8(&tsWal.inited, 0);
+    return code;
+  }
   tsWal.refSetId = taosOpenRef(TSDB_MIN_VNODES, walFreeObj);
 
-  int code = walCreateThread();
+  code = walCreateThread();
   if (code != 0) {
     wError("failed to init wal module since %s", tstrerror(code));
     atomic_store_8(&tsWal.inited, 0);
@@ -64,43 +70,31 @@ int32_t walInit() {
 void walCleanUp() {
   walStopThread();
   taosCloseRef(tsWal.refSetId);
+  atomic_store_8(&tsWal.inited, 0);
   wInfo("wal module is cleaned up");
 }
 
-static int walLoadFileset(SWal *pWal) {
-  DIR *dir = opendir(pWal->path);
-  if (dir == NULL) {
-    wError("vgId:%d, path:%s, failed to open since %s", pWal->vgId, pWal->path, strerror(errno));
-    return -1;
-  }
-
-  struct dirent* ent;
-  while ((ent = readdir(dir)) != NULL) {
-    char *name = ent->d_name;
-    name[WAL_NOSUFFIX_LEN] = 0;
-    //validate file name by regex matching
-    if(1 /* TODO:regex match */) {
-      int64_t fnameInt64 = atoll(name);
-      taosArrayPush(pWal->fileSet, &fnameInt64);
-    }
-  }
-  taosArraySort(pWal->fileSet, compareInt64Val);
-  return 0;
-}
-
 SWal *walOpen(const char *path, SWalCfg *pCfg) {
   SWal *pWal = malloc(sizeof(SWal));
   if (pWal == NULL) {
     terrno = TAOS_SYSTEM_ERROR(errno);
     return NULL;
   }
+  pWal->writeLogTfd = -1;
+  pWal->writeIdxTfd = -1;
 
+  //set config
   pWal->vgId = pCfg->vgId;
-  pWal->curLogTfd = -1;
-  pWal->curIdxTfd = -1;
-  pWal->level = pCfg->walLevel;
   pWal->fsyncPeriod = pCfg->fsyncPeriod;
+  pWal->rollPeriod = pCfg->rollPeriod;
+  pWal->segSize = pCfg->segSize;
+  pWal->level = pCfg->walLevel;
 
+  //init status
+  pWal->lastVersion = -1;
+  pWal->lastRollSeq = -1;
+
+  //init write buffer
   memset(&pWal->head, 0, sizeof(SWalHead));
   pWal->head.sver = 0;
 
@@ -120,7 +114,6 @@ SWal *walOpen(const char *path, SWalCfg *pCfg) {
     walFreeObj(pWal);
     return NULL;
   }
-  walLoadFileset(pWal);
 
   wDebug("vgId:%d, wal:%p is opened, level:%d fsyncPeriod:%d", pWal->vgId, pWal, pWal->level, pWal->fsyncPeriod);
 
@@ -151,10 +144,10 @@ void walClose(SWal *pWal) {
   if (pWal == NULL) return;
 
   pthread_mutex_lock(&pWal->mutex);
-  tfClose(pWal->curLogTfd);
-  tfClose(pWal->curIdxTfd);
-  taosArrayDestroy(pWal->fileSet);
-  pWal->fileSet = NULL;
+  tfClose(pWal->writeLogTfd);
+  tfClose(pWal->writeIdxTfd);
+  /*taosArrayDestroy(pWal->fileInfoSet);*/
+  /*pWal->fileInfoSet = NULL;*/
   pthread_mutex_unlock(&pWal->mutex);
   taosRemoveRef(tsWal.refSetId, pWal->refId);
 }
@@ -164,8 +157,8 @@ static int32_t walInitObj(SWal *pWal) {
     wError("vgId:%d, path:%s, failed to create directory since %s", pWal->vgId, pWal->path, strerror(errno));
     return TAOS_SYSTEM_ERROR(errno);
   }
-  pWal->fileSet = taosArrayInit(0, sizeof(int64_t));
-  if(pWal->fileSet == NULL) {
+  pWal->fileInfoSet = taosArrayInit(0, sizeof(WalFileInfo));
+  if(pWal->fileInfoSet == NULL) {
     wError("vgId:%d, path:%s, failed to init taosArray %s", pWal->vgId, pWal->path, strerror(errno));
     return TAOS_SYSTEM_ERROR(errno);
   }
@@ -178,10 +171,10 @@ static void walFreeObj(void *wal) {
   SWal *pWal = wal;
   wDebug("vgId:%d, wal:%p is freed", pWal->vgId, pWal);
 
-  tfClose(pWal->curLogTfd);
-  tfClose(pWal->curIdxTfd);
-  taosArrayDestroy(pWal->fileSet);
-  pWal->fileSet = NULL;
+  tfClose(pWal->writeLogTfd);
+  tfClose(pWal->writeIdxTfd);
+  taosArrayDestroy(pWal->fileInfoSet);
+  pWal->fileInfoSet = NULL;
   pthread_mutex_destroy(&pWal->mutex);
   tfree(pWal);
 }
@@ -208,9 +201,9 @@ static void walFsyncAll() {
   while (pWal) {
     if (walNeedFsync(pWal)) {
       wTrace("vgId:%d, do fsync, level:%d seq:%d rseq:%d", pWal->vgId, pWal->level, pWal->fsyncSeq, atomic_load_32(&tsWal.seq));
-      int32_t code = tfFsync(pWal->curLogTfd);
+      int32_t code = tfFsync(pWal->writeLogTfd);
       if (code != 0) {
-        wError("vgId:%d, file:%"PRId64".log, failed to fsync since %s", pWal->vgId, pWal->curFileFirstVersion, strerror(code));
+        wError("vgId:%d, file:%"PRId64".log, failed to fsync since %s", pWal->vgId, walGetLastFileFirstVer(pWal), strerror(code));
       }
     }
     pWal = taosIterateRef(tsWal.refSetId, pWal->refId);
diff --git a/source/libs/wal/src/walRead.c b/source/libs/wal/src/walRead.c
index b475183b7b..e9f5bcbc5d 100644
--- a/source/libs/wal/src/walRead.c
+++ b/source/libs/wal/src/walRead.c
@@ -13,16 +13,56 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include "wal.h"
+#include "walInt.h"
+#include "tfile.h"
 #include "tchecksum.h"
 
-static int walValidateChecksum(SWalHead *pHead, void* body, int64_t bodyLen) {
-  return taosCheckChecksum((uint8_t*)pHead, sizeof(SWalHead) - sizeof(uint32_t)*2, pHead->cksumHead) &&
-    taosCheckChecksum(body, bodyLen, pHead->cksumBody);
+static inline int walValidHeadCksum(SWalHead* pHead) {
+  return taosCheckChecksum((uint8_t*)pHead, sizeof(SWalHead) - sizeof(uint32_t)*2, pHead->cksumHead);
 }
 
+static inline int walValidBodyCksum(SWalHead* pHead) {
+  return taosCheckChecksum((uint8_t*)pHead->cont, pHead->len, pHead->cksumBody);
+}
+
+static int walValidCksum(SWalHead *pHead, void* body, int64_t bodyLen) {
+  return walValidHeadCksum(pHead) && walValidBodyCksum(pHead);
+}
 
 int32_t walRead(SWal *pWal, SWalHead **ppHead, int64_t ver) {
+  int code;
+  code = walSeekVer(pWal, ver);
+  if(code != 0) {
+    return code;
+  }
+  if(*ppHead == NULL) {
+    void* ptr = realloc(*ppHead, sizeof(SWalHead));
+    if(ptr == NULL) {
+      return -1;
+    }
+    *ppHead = ptr;
+  }
+  if(tfRead(pWal->writeLogTfd, *ppHead, sizeof(SWalHead)) != sizeof(SWalHead)) {
+    return -1;
+  }
+  //TODO: endian compatibility processing after read
+  if(walValidHeadCksum(*ppHead) != 0) {
+    return -1;
+  }
+  void* ptr = realloc(*ppHead, sizeof(SWalHead) + (*ppHead)->len);
+  if(ptr == NULL) {
+    free(*ppHead);
+    *ppHead = NULL;
+    return -1;
+  }
+  if(tfRead(pWal->writeLogTfd, (*ppHead)->cont, (*ppHead)->len) != (*ppHead)->len) {
+    return -1;
+  }
+  //TODO: endian compatibility processing after read
+  if(walValidBodyCksum(*ppHead) != 0) {
+    return -1;
+  }
+  
   return 0;
 }
 
diff --git a/source/libs/wal/src/walWrite.c b/source/libs/wal/src/walWrite.c
index 69c83a9912..0c4989300f 100644
--- a/source/libs/wal/src/walWrite.c
+++ b/source/libs/wal/src/walWrite.c
@@ -21,29 +21,63 @@
 #include "tfile.h"
 #include "walInt.h"
 
+static void walFtruncate(SWal *pWal, int64_t ver);
+
 int32_t walCommit(SWal *pWal, int64_t ver) {
+  ASSERT(pWal->snapshotVersion <= pWal->commitVersion);
+  ASSERT(pWal->commitVersion <= pWal->lastVersion);
+  ASSERT(ver >= pWal->commitVersion);
+  ASSERT(ver <= pWal->lastVersion);
+  pWal->commitVersion = ver;
   return 0;
 }
 
 int32_t walRollback(SWal *pWal, int64_t ver) {
   //TODO: ftruncate
+  ASSERT(ver > pWal->commitVersion);
+  ASSERT(ver <= pWal->lastVersion);
+  //seek position
+  walSeekVer(pWal, ver); 
+  walFtruncate(pWal, ver);
   return 0;
 }
 
 int32_t walTakeSnapshot(SWal *pWal, int64_t ver) {
   pWal->snapshotVersion = ver;
+  int ts = taosGetTimestampSec();
 
+  int deleteCnt = 0;
+  int64_t newTotSize = pWal->totSize;
+  WalFileInfo tmp;
+  tmp.firstVer = ver;
   //mark files safe to delete
-  int64_t* pRet = taosArraySearch(pWal->fileSet, &ver, compareInt64Val, TD_LE);
-  if(pRet != pWal->fileSet->pData) {
-    //delete files until less than retention size
-    
-    //find first file that exceeds retention time
-    
+  WalFileInfo* pInfo = taosArraySearch(pWal->fileInfoSet, &tmp, compareWalFileInfo, TD_LE);
+  //iterate files, until the searched result
+  for(WalFileInfo* iter = pWal->fileInfoSet->pData; iter < pInfo; iter++) {
+    if(pWal->totSize > pWal->retentionSize ||
+        iter->closeTs + pWal->retentionPeriod > ts) {
+      //delete according to file size or close time
+      deleteCnt++;
+      newTotSize -= iter->fileSize;
+    }
+  }
+  char fnameStr[WAL_FILE_LEN];
+  //remove file
+  for(int i = 0; i < deleteCnt; i++) {
+    WalFileInfo* pInfo = taosArrayGet(pWal->fileInfoSet, i);
+    walBuildLogName(pWal, pInfo->firstVer, fnameStr); 
+    remove(fnameStr);
+    walBuildIdxName(pWal, pInfo->firstVer, fnameStr); 
+    remove(fnameStr);
   }
 
-  //delete files living longer than retention limit
-  //remove file from fileset
+  //save snapshot ver, commit ver
+
+
+  //make new array, remove files
+  taosArrayPopFrontBatch(pWal->fileInfoSet, deleteCnt); 
+  pWal->totSize = newTotSize;
+
   return 0;
 }
 
@@ -138,105 +172,122 @@ void walRemoveAllOldFiles(void *handle) {
 }
 #endif
 
-static int walRoll(SWal *pWal) {
+int walRoll(SWal *pWal) {
   int code = 0;
-  code = tfClose(pWal->curIdxTfd);
-  if(code != 0) {
-    return code;
+  if(pWal->writeIdxTfd != -1) {
+    code = tfClose(pWal->writeIdxTfd);
+    if(code != 0) {
+      return -1;
+    }
   }
-  code = tfClose(pWal->curLogTfd);
-  if(code != 0) {
-    return code;
+  if(pWal->writeLogTfd != -1) {
+    code = tfClose(pWal->writeLogTfd);
+    if(code != 0) {
+      return -1;
+    }
   }
   int64_t idxTfd, logTfd;
   //create new file
   int64_t newFileFirstVersion = pWal->lastVersion + 1;
   char fnameStr[WAL_FILE_LEN];
-  sprintf(fnameStr, "%"PRId64"."WAL_INDEX_SUFFIX, newFileFirstVersion);
+  walBuildIdxName(pWal, newFileFirstVersion, fnameStr);
   idxTfd = tfOpenCreateWrite(fnameStr);
-  sprintf(fnameStr, "%"PRId64"."WAL_LOG_SUFFIX, newFileFirstVersion);
+  if(idxTfd < 0) {
+    ASSERT(0);
+    return -1;
+  }
+  walBuildLogName(pWal, newFileFirstVersion, fnameStr);
   logTfd = tfOpenCreateWrite(fnameStr);
+  if(logTfd < 0) {
+    ASSERT(0);
+    return -1;
+  }
+  code = walRollFileInfo(pWal);
+  if(code != 0) {
+    ASSERT(0);
+    return -1;
+  }
 
-  taosArrayPush(pWal->fileSet, &newFileFirstVersion);
-  
   //switch file
-  pWal->curIdxTfd = idxTfd;
-  pWal->curLogTfd = logTfd;
+  pWal->writeIdxTfd = idxTfd;
+  pWal->writeLogTfd = logTfd;
   //change status
-  pWal->curFileLastVersion = -1;
-  pWal->curFileFirstVersion = newFileFirstVersion; 
-  pWal->curVersion = newFileFirstVersion;
-  pWal->curLogOffset = 0;
   pWal->curStatus = WAL_CUR_FILE_WRITABLE & WAL_CUR_POS_WRITABLE;
 
-  pWal->lastFileName = newFileFirstVersion;
-  pWal->lastFileWriteSize = 0;
   pWal->lastRollSeq = walGetSeq();
   return 0;
 }
 
 int walChangeFileToLast(SWal *pWal) {
   int64_t idxTfd, logTfd;
-  int64_t* pRet = taosArrayGetLast(pWal->fileSet);
+  WalFileInfo* pRet = taosArrayGetLast(pWal->fileInfoSet);
   ASSERT(pRet != NULL);
-  int64_t fname = *pRet;
+  int64_t fileFirstVer = pRet->firstVer;
 
   char fnameStr[WAL_FILE_LEN];
-  sprintf(fnameStr, "%"PRId64"."WAL_INDEX_SUFFIX, fname);
+  walBuildIdxName(pWal, fileFirstVer, fnameStr);
   idxTfd = tfOpenReadWrite(fnameStr);
-  sprintf(fnameStr, "%"PRId64"."WAL_LOG_SUFFIX, fname);
+  if(idxTfd < 0) {
+    return -1;
+  }
+  walBuildLogName(pWal, fileFirstVer, fnameStr);
   logTfd = tfOpenReadWrite(fnameStr);
+  if(logTfd < 0) {
+    return -1;
+  }
   //switch file
-  pWal->curIdxTfd = idxTfd;
-  pWal->curLogTfd = logTfd;
+  pWal->writeIdxTfd = idxTfd;
+  pWal->writeLogTfd = logTfd;
   //change status
-  pWal->curFileLastVersion = -1;
-  pWal->curFileFirstVersion = fname; 
-  pWal->curVersion = fname;
-  pWal->curLogOffset = 0;
+  pWal->curVersion = fileFirstVer;
   pWal->curStatus = WAL_CUR_FILE_WRITABLE;
   return 0;
 }
 
-int walWriteIndex(SWal *pWal, int64_t ver, int64_t offset) {
+static int walWriteIndex(SWal *pWal, int64_t ver, int64_t offset) {
   int code = 0;
   //get index file
-  if(!tfValid(pWal->curIdxTfd)) {
+  if(!tfValid(pWal->writeIdxTfd)) {
     code = TAOS_SYSTEM_ERROR(errno);
-    wError("vgId:%d, file:%"PRId64".idx, failed to open since %s", pWal->vgId, pWal->curFileFirstVersion, strerror(errno));
+
+    wError("vgId:%d, file:%"PRId64".idx, failed to open since %s", pWal->vgId, walGetLastFileFirstVer(pWal), strerror(errno));
+    return code;
   }
   int64_t writeBuf[2] = { ver, offset };
-  int size = tfWrite(pWal->curIdxTfd, writeBuf, sizeof(writeBuf));
+  int size = tfWrite(pWal->writeIdxTfd, writeBuf, sizeof(writeBuf));
   if(size != sizeof(writeBuf)) {
-    //TODO:
+    return -1;
   }
   return 0;
 }
 
-int64_t walWrite(SWal *pWal, int64_t index, uint8_t msgType, void *body, int32_t bodyLen) {
+int64_t walWrite(SWal *pWal, int64_t index, uint8_t msgType, const void *body, int32_t bodyLen) {
   if (pWal == NULL) return -1;
+  int code = 0;
 
   // no wal
   if (pWal->level == TAOS_WAL_NOLOG) return 0;
 
   if (index == pWal->lastVersion + 1) {
-    int64_t passed = walGetSeq() - pWal->lastRollSeq;
-    if(passed > pWal->rollPeriod) {
-      walRoll(pWal);
-    } else if(pWal->lastFileWriteSize > pWal->segSize) {
-      walRoll(pWal);
+    if(taosArrayGetSize(pWal->fileInfoSet) == 0) {
+      code = walRoll(pWal);
+      ASSERT(code == 0);
     } else {
-      walChangeFileToLast(pWal);
+      int64_t passed = walGetSeq() - pWal->lastRollSeq;
+      if(pWal->rollPeriod != -1 && passed > pWal->rollPeriod) {
+        walRoll(pWal);
+      } else if(pWal->segSize != -1 && walGetLastFileSize(pWal) > pWal->segSize) {
+        walRoll(pWal);
+      }
     }
   } else {
     //reject skip log or rewrite log
     //must truncate explicitly first
     return -1;
   }
-  if (!tfValid(pWal->curLogTfd)) return 0;
+  /*if (!tfValid(pWal->curLogTfd)) return 0;*/
 
   pWal->head.version = index;
-  int32_t code = 0;
 
   pWal->head.signature = WAL_SIGNATURE;
   pWal->head.len = bodyLen;
@@ -247,22 +298,27 @@ int64_t walWrite(SWal *pWal, int64_t index, uint8_t msgType, void *body, int32_t
 
   pthread_mutex_lock(&pWal->mutex);
 
-  if (tfWrite(pWal->curLogTfd, &pWal->head, sizeof(SWalHead)) != sizeof(SWalHead)) {
+  if (tfWrite(pWal->writeLogTfd, &pWal->head, sizeof(SWalHead)) != sizeof(SWalHead)) {
     //ftruncate
     code = TAOS_SYSTEM_ERROR(errno);
-    wError("vgId:%d, file:%"PRId64".log, failed to write since %s", pWal->vgId, pWal->curFileFirstVersion, strerror(errno));
+    wError("vgId:%d, file:%"PRId64".log, failed to write since %s", pWal->vgId, walGetLastFileFirstVer(pWal), strerror(errno));
   }
 
-  if (tfWrite(pWal->curLogTfd, &body, bodyLen) != bodyLen) {
+  if (tfWrite(pWal->writeLogTfd, &body, bodyLen) != bodyLen) {
     //ftruncate
     code = TAOS_SYSTEM_ERROR(errno);
-    wError("vgId:%d, file:%"PRId64".log, failed to write since %s", pWal->vgId, pWal->curFileFirstVersion, strerror(errno));
+    wError("vgId:%d, file:%"PRId64".log, failed to write since %s", pWal->vgId, walGetLastFileFirstVer(pWal), strerror(errno));
+  }
+  code = walWriteIndex(pWal, index, walGetCurFileOffset(pWal));
+  if(code != 0) {
+    //TODO
   }
-  walWriteIndex(pWal, index, pWal->curLogOffset);
-  pWal->curLogOffset += sizeof(SWalHead) + bodyLen;
 
   //set status
   pWal->lastVersion = index;
+  pWal->totSize += sizeof(SWalHead) + bodyLen;
+  walGetCurFileInfo(pWal)->lastVer = index;
+  walGetCurFileInfo(pWal)->fileSize += sizeof(SWalHead) + bodyLen;
   
   pthread_mutex_unlock(&pWal->mutex);
 
@@ -270,12 +326,12 @@ int64_t walWrite(SWal *pWal, int64_t index, uint8_t msgType, void *body, int32_t
 }
 
 void walFsync(SWal *pWal, bool forceFsync) {
-  if (pWal == NULL || !tfValid(pWal->curLogTfd)) return;
+  if (pWal == NULL || !tfValid(pWal->writeLogTfd)) return;
 
   if (forceFsync || (pWal->level == TAOS_WAL_FSYNC && pWal->fsyncPeriod == 0)) {
-    wTrace("vgId:%d, fileId:%"PRId64".log, do fsync", pWal->vgId, pWal->curFileFirstVersion);
-    if (tfFsync(pWal->curLogTfd) < 0) {
-      wError("vgId:%d, file:%"PRId64".log, fsync failed since %s", pWal->vgId, pWal->curFileFirstVersion, strerror(errno));
+    wTrace("vgId:%d, fileId:%"PRId64".log, do fsync", pWal->vgId, walGetCurFileFirstVer(pWal));
+    if (tfFsync(pWal->writeLogTfd) < 0) {
+      wError("vgId:%d, file:%"PRId64".log, fsync failed since %s", pWal->vgId, walGetCurFileFirstVer(pWal), strerror(errno));
     }
   }
 }
@@ -348,8 +404,36 @@ int32_t walGetWalFile(void *handle, char *fileName, int64_t *fileId) {
 }
 #endif
 
-static void walFtruncate(SWal *pWal, int64_t tfd, int64_t offset) {
-  tfFtruncate(tfd, offset);
+static int walValidateOffset(SWal* pWal, int64_t ver) {
+  int code = 0;
+  SWalHead *pHead = NULL;
+  code = (int)walRead(pWal, &pHead, ver);
+  if(pHead->version != ver) {
+    return -1;
+  }
+  return 0;
+}
+
+static int64_t walGetOffset(SWal* pWal, int64_t ver) {
+  int code = walSeekVer(pWal, ver);
+  if(code != 0) {
+    return -1;
+  }
+
+  code = walValidateOffset(pWal, ver);
+  if(code != 0) {
+    return -1;
+  }
+
+  return 0;
+}
+
+static void walFtruncate(SWal *pWal, int64_t ver) {
+  int64_t tfd = pWal->writeLogTfd;
+  tfFtruncate(tfd, ver);
+  tfFsync(tfd);
+  tfd = pWal->writeIdxTfd;
+  tfFtruncate(tfd, ver * WAL_IDX_ENTRY_SIZE);
   tfFsync(tfd);
 }
 
diff --git a/source/libs/wal/test/CMakeLists.txt b/source/libs/wal/test/CMakeLists.txt
new file mode 100644
index 0000000000..1c0a3a162a
--- /dev/null
+++ b/source/libs/wal/test/CMakeLists.txt
@@ -0,0 +1,20 @@
+add_executable(walTest "")
+target_sources(walTest
+    PRIVATE
+    "walMetaTest.cpp"
+)
+target_include_directories(walTest
+    PUBLIC
+    "${CMAKE_SOURCE_DIR}/include/libs/wal"
+    "${CMAKE_CURRENT_SOURCE_DIR}/../inc"
+)
+
+target_link_libraries(walTest
+    wal
+    gtest_main
+)
+enable_testing()
+add_test(
+    NAME wal_test
+    COMMAND walTest
+)
diff --git a/source/libs/wal/test/walMetaTest.cpp b/source/libs/wal/test/walMetaTest.cpp
new file mode 100644
index 0000000000..96258662a1
--- /dev/null
+++ b/source/libs/wal/test/walMetaTest.cpp
@@ -0,0 +1,149 @@
+#include <gtest/gtest.h>
+#include <cstring>
+#include <iostream>
+#include <queue>
+
+#include "walInt.h"
+
+class WalCleanEnv : public ::testing::Test {
+  protected:
+    static void SetUpTestCase() {
+      int code = walInit();
+      ASSERT(code == 0);
+    }
+
+    static void TearDownTestCase() {
+      walCleanUp();
+    }
+
+    void SetUp() override {
+      taosRemoveDir(pathName);
+      SWalCfg* pCfg = (SWalCfg*)malloc(sizeof(SWal));
+      memset(pCfg, 0, sizeof(SWalCfg));
+      pCfg->rollPeriod = -1;
+      pCfg->segSize = -1;
+      pCfg->walLevel = TAOS_WAL_FSYNC;
+      pWal = walOpen(pathName, pCfg);
+      ASSERT(pWal != NULL);
+    }
+
+    void TearDown() override {
+      walClose(pWal);
+      pWal = NULL;
+    }
+
+    SWal* pWal = NULL;
+    const char* pathName = "/tmp/wal_test";
+};
+
+class WalKeepEnv : public ::testing::Test {
+  protected:
+    static void SetUpTestCase() {
+      int code = walInit();
+      ASSERT(code == 0);
+    }
+
+    static void TearDownTestCase() {
+      walCleanUp();
+    }
+
+    void SetUp() override {
+      SWalCfg* pCfg = (SWalCfg*)malloc(sizeof(SWal)); 
+      memset(pCfg, 0, sizeof(SWalCfg));
+      pCfg->rollPeriod = -1;
+      pCfg->segSize = -1;
+      pCfg->walLevel = TAOS_WAL_FSYNC;
+      pWal = walOpen(pathName, pCfg);
+      ASSERT(pWal != NULL);
+    }
+
+    void TearDown() override {
+      walClose(pWal);
+      pWal = NULL;
+    }
+
+    SWal* pWal = NULL;
+    const char* pathName = "/tmp/wal_test";
+};
+
+TEST_F(WalCleanEnv, createNew) {
+  walRollFileInfo(pWal);
+  ASSERT(pWal->fileInfoSet != NULL);
+  ASSERT_EQ(pWal->fileInfoSet->size, 1);
+  WalFileInfo* pInfo = (WalFileInfo*)taosArrayGetLast(pWal->fileInfoSet);
+  ASSERT_EQ(pInfo->firstVer, 0);
+  ASSERT_EQ(pInfo->lastVer, -1);
+  ASSERT_EQ(pInfo->closeTs, -1);
+  ASSERT_EQ(pInfo->fileSize, 0);
+}
+
+TEST_F(WalCleanEnv, serialize) {
+  int code = walRollFileInfo(pWal);
+  ASSERT(code == 0);
+  ASSERT(pWal->fileInfoSet != NULL);
+
+  code = walRollFileInfo(pWal);
+  ASSERT(code == 0);
+  code = walRollFileInfo(pWal);
+  ASSERT(code == 0);
+  code = walRollFileInfo(pWal);
+  ASSERT(code == 0);
+  code = walRollFileInfo(pWal);
+  ASSERT(code == 0);
+  code = walRollFileInfo(pWal);
+  ASSERT(code == 0);
+  char*ss = walMetaSerialize(pWal);
+  printf("%s\n", ss);
+  code = walWriteMeta(pWal);
+  ASSERT(code == 0);
+}
+
+TEST_F(WalCleanEnv, removeOldMeta) {
+  int code = walRollFileInfo(pWal);
+  ASSERT(code == 0);
+  ASSERT(pWal->fileInfoSet != NULL);
+  code = walWriteMeta(pWal);
+  ASSERT(code == 0);
+  code = walRollFileInfo(pWal);
+  ASSERT(code == 0);
+  code = walWriteMeta(pWal);
+  ASSERT(code == 0);
+}
+
+TEST_F(WalKeepEnv, readOldMeta) {
+  int code = walRollFileInfo(pWal);
+  ASSERT(code == 0);
+  code = walWriteMeta(pWal);
+  ASSERT(code == 0);
+  code = walRollFileInfo(pWal);
+  ASSERT(code == 0);
+  code = walWriteMeta(pWal);
+  ASSERT(code == 0);
+  char*oldss = walMetaSerialize(pWal);
+
+  TearDown();
+  SetUp();
+  code = walReadMeta(pWal);
+  ASSERT(code == 0);
+  char* newss = walMetaSerialize(pWal);
+
+  int len = strlen(oldss);
+  ASSERT_EQ(len, strlen(newss));
+  for(int i = 0; i < len; i++) {
+    EXPECT_EQ(oldss[i], newss[i]);
+  }
+}
+
+TEST_F(WalKeepEnv, write) {
+  const char* ranStr = "tvapq02tcp";
+  const int len = strlen(ranStr);
+  int code;
+  for(int i = 0; i < 10; i++) {
+    code = walWrite(pWal, i, i+1, (void*)ranStr, len); 
+    ASSERT_EQ(code, 0);
+    code = walWrite(pWal, i+2, i, (void*)ranStr, len);
+    ASSERT_EQ(code, -1);
+  }
+  code = walWriteMeta(pWal);
+  ASSERT_EQ(code, 0);
+}
diff --git a/source/libs/wal/test/walTests.cpp b/source/libs/wal/test/walTests.cpp
deleted file mode 100644
index 505728fbe4..0000000000
--- a/source/libs/wal/test/walTests.cpp
+++ /dev/null
@@ -1,137 +0,0 @@
-/*
- * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
- *
- * This program is free software: you can use, redistribute, and/or modify
- * it under the terms of the GNU Affero General Public License, version 3
- * or later ("AGPL"), as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-//#define _DEFAULT_SOURCE
-#include "os.h"
-#include "tutil.h"
-#include "tglobal.h"
-#include "tlog.h"
-#include "twal.h"
-#include "tfile.h"
-
-int64_t  ver = 0;
-void    *pWal = NULL;
-
-int writeToQueue(void *pVnode, void *data, int type, void *pMsg) {
-  // do nothing
-  SWalHead *pHead = data;
-
-  if (pHead->version > ver)
-    ver = pHead->version;
-
-  walWrite(pWal, pHead);
-
-  return 0;
-}
-
-int main(int argc, char *argv[]) {
-  char path[128] = "/tmp/wal";
-  int  level = 2;
-  int  total = 5;
-  int  rows = 10000;
-  int  size = 128;
-  int  keep = 0;
-
-  for (int i=1; i<argc; ++i) {
-    if (strcmp(argv[i], "-p")==0 && i < argc-1) {
-      tstrncpy(path, argv[++i], sizeof(path));
-    } else if (strcmp(argv[i], "-l")==0 && i < argc-1) {
-      level = atoi(argv[++i]);
-    } else if (strcmp(argv[i], "-r")==0 && i < argc-1) {
-      rows = atoi(argv[++i]);
-    } else if (strcmp(argv[i], "-k")==0 && i < argc-1) {
-      keep = atoi(argv[++i]);
-    } else if (strcmp(argv[i], "-t")==0 && i < argc-1) {
-      total = atoi(argv[++i]);
-    } else if (strcmp(argv[i], "-s")==0 && i < argc-1) {
-      size = atoi(argv[++i]);
-    } else if (strcmp(argv[i], "-v")==0 && i < argc-1) {
-      ver = atoll(argv[++i]);
-    } else if (strcmp(argv[i], "-d")==0 && i < argc-1) {
-      dDebugFlag = atoi(argv[++i]);
-    } else {
-      printf("\nusage: %s [options] \n", argv[0]);
-      printf("  [-p path]: wal file path default is:%s\n", path);
-      printf("  [-l level]: log level, default is:%d\n", level);
-      printf("  [-t total]: total wal files, default is:%d\n", total);
-      printf("  [-r rows]: rows of records per wal file, default is:%d\n", rows);
-      printf("  [-k keep]: keep the wal after closing, default is:%d\n", keep);
-      printf("  [-v version]: initial version, default is:%" PRId64 "\n", ver);
-      printf("  [-d debugFlag]: debug flag, default:%d\n", dDebugFlag);
-      printf("  [-h help]: print out this help\n\n");
-      exit(0);
-    }
-  }
-
-  taosInitLog("wal.log", 100000, 10);
-  tfInit();
-  walInit();
-
-  SWalCfg walCfg = {0};
-  walCfg.walLevel = level;
-  walCfg.keep = keep;
-
-  pWal = walOpen(path, &walCfg);
-  if (pWal == NULL) {
-    printf("failed to open wal\n");
-    exit(-1);
-  }
-
-  int ret = walRestore(pWal, NULL, writeToQueue);
-  if (ret <0) {
-    printf("failed to restore wal\n");
-    exit(-1);
-  }
-
-  printf("version starts from:%" PRId64 "\n", ver);
-  
-  int contLen = sizeof(SWalHead) + size;
-  SWalHead *pHead = (SWalHead *) malloc(contLen);
-
-  for (int i=0; i<total; ++i) {
-    for (int k=0; k<rows; ++k) {
-      pHead->version = ++ver;
-      pHead->len = size;
-      walWrite(pWal, pHead);
-    }
-       
-    printf("renew a wal, i:%d\n", i);
-    walRenew(pWal);
-  }
-
-  printf("%d wal files are written\n", total);
-
-  int64_t index = 0;
-  char    name[256];
-
-  while (1) {
-    int code = walGetWalFile(pWal, name, &index);
-    if (code == -1) {
-      printf("failed to get wal file, index:%" PRId64 "\n", index);
-      break;
-    }
-
-    printf("index:%" PRId64 " wal:%s\n", index, name);
-    if (code == 0) break;
-  }
-
-  getchar();
-
-  walClose(pWal);
-  walCleanUp();
-  tfCleanup();
-
-  return 0;
-}
diff --git a/source/util/src/tarray.c b/source/util/src/tarray.c
index 007ce06829..ff52477a6f 100644
--- a/source/util/src/tarray.c
+++ b/source/util/src/tarray.c
@@ -237,6 +237,16 @@ void taosArraySet(SArray* pArray, size_t index, void* pData) {
   memcpy(TARRAY_GET_ELEM(pArray, index), pData, pArray->elemSize);
 }
 
+void taosArrayPopFrontBatch(SArray* pArray, size_t cnt) {
+  assert(cnt <= pArray->size);
+  pArray->size = pArray->size - cnt;
+  if(pArray->size == 0) {
+    pArray->size = 0;
+    return;
+  }
+  memmove(pArray->pData, (char*)pArray->pData + cnt * pArray->elemSize, pArray->size);
+}
+
 void taosArrayRemove(SArray* pArray, size_t index) {
   assert(index < pArray->size);
   
diff --git a/source/util/src/tfile.c b/source/util/src/tfile.c
index 5d4789aae6..313f1d97af 100644
--- a/source/util/src/tfile.c
+++ b/source/util/src/tfile.c
@@ -22,20 +22,26 @@
 
 static int32_t tsFileRsetId = -1;
 
+static int8_t tfInited = 0;
+
 static void tfCloseFile(void *p) {
   taosCloseFile((int32_t)(uintptr_t)p);
 }
 
 int32_t tfInit() {
+  int8_t old = atomic_val_compare_exchange_8(&tfInited, 0, 1);
+  if(old == 1) return 0;
   tsFileRsetId = taosOpenRef(2000, tfCloseFile);
   if (tsFileRsetId > 0) {
     return 0;
   } else {
+    atomic_store_8(&tfInited, 0);
     return -1;
   }
 }
 
 void tfCleanup() {
+  atomic_store_8(&tfInited, 0);
   if (tsFileRsetId >= 0) taosCloseRef(tsFileRsetId);
   tsFileRsetId = -1;
 }
diff --git a/source/util/src/tmd5.c b/source/util/src/tmd5.c
index 9cc4b3b9d5..807f3c8122 100644
--- a/source/util/src/tmd5.c
+++ b/source/util/src/tmd5.c
@@ -84,8 +84,8 @@ static uint8_t PADDING[64] = {0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x
 /* The routine MD5Init initializes the message-digest context
    mdContext. All fields are set to zero.
  */
-void MD5Init(MD5_CTX *mdContext) {
-  memset(mdContext, 0, sizeof(MD5_CTX));
+void tMD5Init(T_MD5_CTX *mdContext) {
+  memset(mdContext, 0, sizeof(T_MD5_CTX));
 
   /* Load magic initialization constants. */
   mdContext->buf[0] = (uint32_t)0x67452301;
@@ -98,7 +98,7 @@ void MD5Init(MD5_CTX *mdContext) {
 account for the presence of each of the characters inBuf[0..inLen-1]
 in the message whose digest is being computed.
 */
-void MD5Update(MD5_CTX *mdContext, uint8_t *inBuf, unsigned int inLen) {
+void tMD5Update(T_MD5_CTX *mdContext, uint8_t *inBuf, unsigned int inLen) {
   uint32_t     in[16];
   int          mdi;
   unsigned int i, ii;
@@ -129,7 +129,7 @@ void MD5Update(MD5_CTX *mdContext, uint8_t *inBuf, unsigned int inLen) {
 /* The routine MD5Final terminates the message-digest computation and
 ends with the desired message digest in mdContext->digest[0...15].
 */
-void MD5Final(MD5_CTX *mdContext) {
+void tMD5Final(T_MD5_CTX *mdContext) {
   uint32_t     in[16];
   int          mdi;
   unsigned int i, ii;
@@ -144,7 +144,7 @@ void MD5Final(MD5_CTX *mdContext) {
 
   /* pad out to 56 mod 64 */
   padLen = (mdi < 56) ? (56 - mdi) : (120 - mdi);
-  MD5Update(mdContext, PADDING, padLen);
+  tMD5Update(mdContext, PADDING, padLen);
 
   /* append length in bits and transform */
   for (i = 0, ii = 0; i < 14; i++, ii += 4)