91 lines
3 KiB
Go
91 lines
3 KiB
Go
// Copyright 2012 Gary Burd
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//
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// Licensed under the Apache License, Version 2.0 (the "License"): you may
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// not use this file except in compliance with the License. You may obtain
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// a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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// License for the specific language governing permissions and limitations
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// under the License.
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package redis
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import (
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"crypto/sha1"
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"encoding/hex"
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"io"
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"strings"
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)
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// Script encapsulates the source, hash and key count for a Lua script. See
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// http://redis.io/commands/eval for information on scripts in Redis.
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type Script struct {
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keyCount int
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src string
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hash string
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}
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// NewScript returns a new script object. If keyCount is greater than or equal
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// to zero, then the count is automatically inserted in the EVAL command
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// argument list. If keyCount is less than zero, then the application supplies
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// the count as the first value in the keysAndArgs argument to the Do, Send and
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// SendHash methods.
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func NewScript(keyCount int, src string) *Script {
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h := sha1.New()
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io.WriteString(h, src)
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return &Script{keyCount, src, hex.EncodeToString(h.Sum(nil))}
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}
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func (s *Script) args(spec string, keysAndArgs []interface{}) []interface{} {
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var args []interface{}
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if s.keyCount < 0 {
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args = make([]interface{}, 1+len(keysAndArgs))
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args[0] = spec
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copy(args[1:], keysAndArgs)
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} else {
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args = make([]interface{}, 2+len(keysAndArgs))
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args[0] = spec
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args[1] = s.keyCount
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copy(args[2:], keysAndArgs)
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}
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return args
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}
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// Hash returns the script hash.
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func (s *Script) Hash() string {
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return s.hash
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}
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// Do evaluates the script. Under the covers, Do optimistically evaluates the
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// script using the EVALSHA command. If the command fails because the script is
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// not loaded, then Do evaluates the script using the EVAL command (thus
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// causing the script to load).
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func (s *Script) Do(c Conn, keysAndArgs ...interface{}) (interface{}, error) {
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v, err := c.Do("EVALSHA", s.args(s.hash, keysAndArgs)...)
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if e, ok := err.(Error); ok && strings.HasPrefix(string(e), "NOSCRIPT ") {
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v, err = c.Do("EVAL", s.args(s.src, keysAndArgs)...)
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}
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return v, err
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}
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// SendHash evaluates the script without waiting for the reply. The script is
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// evaluated with the EVALSHA command. The application must ensure that the
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// script is loaded by a previous call to Send, Do or Load methods.
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func (s *Script) SendHash(c Conn, keysAndArgs ...interface{}) error {
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return c.Send("EVALSHA", s.args(s.hash, keysAndArgs)...)
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}
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// Send evaluates the script without waiting for the reply.
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func (s *Script) Send(c Conn, keysAndArgs ...interface{}) error {
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return c.Send("EVAL", s.args(s.src, keysAndArgs)...)
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}
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// Load loads the script without evaluating it.
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func (s *Script) Load(c Conn) error {
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_, err := c.Do("SCRIPT", "LOAD", s.src)
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return err
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}
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