support multi transaction

multi.go

@@ -0,0 +1,94 @@
+package godis
+
+import (
+	"github.com/hdt3213/godis/interface/redis"
+	"github.com/hdt3213/godis/redis/reply"
+	"strings"
+)
+
+func startMulti(db *DB, conn redis.Connection) redis.Reply {
+	if conn.InMultiState() {
+		return reply.MakeErrReply("ERR MULTI calls can not be nested")
+	}
+	conn.SetMultiState(true)
+	return reply.MakeOkReply()
+}
+
+func enqueueCmd(db *DB, conn redis.Connection, cmdLine [][]byte) redis.Reply {
+	cmdName := strings.ToLower(string(cmdLine[0]))
+	cmd, ok := cmdTable[cmdName]
+	if !ok {
+		return reply.MakeErrReply("ERR unknown command '" + cmdName + "'")
+	}
+	if cmd.prepare == nil {
+		return reply.MakeErrReply("ERR command '" + cmdName + "' cannot be used in MULTI")
+	}
+	if !validateArity(cmd.arity, cmdLine) {
+		// difference with redis: we won't enqueue command line with wrong arity
+		return reply.MakeArgNumErrReply(cmdName)
+	}
+	conn.EnqueueCmd(cmdLine)
+	return reply.MakeQueuedReply()
+}
+
+func execMulti(db *DB, conn redis.Connection) redis.Reply {
+	if !conn.InMultiState() {
+		return reply.MakeErrReply("ERR EXEC without MULTI")
+	}
+	defer conn.SetMultiState(false)
+	cmdLines := conn.GetQueuedCmdLine()
+
+	// prepare
+	writeKeys := make([]string, 0) // may contains duplicate
+	readKeys := make([]string, 0)
+	for _, cmdLine := range cmdLines {
+		cmdName := strings.ToLower(string(cmdLine[0]))
+		cmd := cmdTable[cmdName]
+		prepare := cmd.prepare
+		write, read := prepare(cmdLine[1:])
+		writeKeys = append(writeKeys, write...)
+		readKeys = append(readKeys, read...)
+	}
+	db.RWLocks(writeKeys, readKeys)
+	defer db.RWUnLocks(writeKeys, readKeys)
+
+	// execute
+	results := make([][]byte, 0, len(cmdLines))
+	aborted := false
+	undoCmdLines := make([][]CmdLine, 0, len(cmdLines))
+	for _, cmdLine := range cmdLines {
+		undoCmdLines = append(undoCmdLines, db.GetUndoLogs(cmdLine))
+		result := db.ExecWithLock(cmdLine)
+		if reply.IsErrorReply(result) {
+			aborted = true
+			// don't rollback failed commands
+			undoCmdLines = undoCmdLines[:len(undoCmdLines)-1]
+			break
+		}
+		results = append(results, result.ToBytes())
+	}
+	if !aborted {
+		return reply.MakeMultiRawReply(results)
+	}
+	// undo if aborted
+	size := len(undoCmdLines)
+	for i := size - 1; i >= 0; i-- {
+		curCmdLines := undoCmdLines[i]
+		if len(curCmdLines) == 0 {
+			continue
+		}
+		for _, cmdLine := range curCmdLines {
+			db.ExecWithLock(cmdLine)
+		}
+	}
+	return reply.MakeErrReply("EXECABORT Transaction discarded because of previous errors.")
+}
+
+func discardMulti(db *DB, conn redis.Connection) redis.Reply {
+	if !conn.InMultiState() {
+		return reply.MakeErrReply("ERR DISCARD without MULTI")
+	}
+	conn.ClearQueuedCmds()
+	conn.SetMultiState(false)
+	return reply.MakeQueuedReply()
+}