177 lines
6.4 KiB
Go
177 lines
6.4 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 is a client for the Redis database.
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//
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// The Redigo FAQ (https://github.com/gomodule/redigo/wiki/FAQ) contains more
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// documentation about this package.
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//
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// Connections
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//
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// The Conn interface is the primary interface for working with Redis.
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// Applications create connections by calling the Dial, DialWithTimeout or
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// NewConn functions. In the future, functions will be added for creating
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// sharded and other types of connections.
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//
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// The application must call the connection Close method when the application
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// is done with the connection.
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//
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// Executing Commands
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//
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// The Conn interface has a generic method for executing Redis commands:
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//
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// Do(commandName string, args ...interface{}) (reply interface{}, err error)
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//
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// The Redis command reference (http://redis.io/commands) lists the available
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// commands. An example of using the Redis APPEND command is:
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//
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// n, err := conn.Do("APPEND", "key", "value")
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//
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// The Do method converts command arguments to bulk strings for transmission
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// to the server as follows:
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//
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// Go Type Conversion
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// []byte Sent as is
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// string Sent as is
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// int, int64 strconv.FormatInt(v)
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// float64 strconv.FormatFloat(v, 'g', -1, 64)
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// bool true -> "1", false -> "0"
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// nil ""
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// all other types fmt.Fprint(w, v)
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//
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// Redis command reply types are represented using the following Go types:
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//
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// Redis type Go type
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// error redis.Error
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// integer int64
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// simple string string
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// bulk string []byte or nil if value not present.
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// array []interface{} or nil if value not present.
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//
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// Use type assertions or the reply helper functions to convert from
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// interface{} to the specific Go type for the command result.
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//
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// Pipelining
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//
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// Connections support pipelining using the Send, Flush and Receive methods.
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//
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// Send(commandName string, args ...interface{}) error
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// Flush() error
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// Receive() (reply interface{}, err error)
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//
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// Send writes the command to the connection's output buffer. Flush flushes the
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// connection's output buffer to the server. Receive reads a single reply from
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// the server. The following example shows a simple pipeline.
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//
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// c.Send("SET", "foo", "bar")
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// c.Send("GET", "foo")
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// c.Flush()
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// c.Receive() // reply from SET
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// v, err = c.Receive() // reply from GET
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//
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// The Do method combines the functionality of the Send, Flush and Receive
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// methods. The Do method starts by writing the command and flushing the output
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// buffer. Next, the Do method receives all pending replies including the reply
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// for the command just sent by Do. If any of the received replies is an error,
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// then Do returns the error. If there are no errors, then Do returns the last
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// reply. If the command argument to the Do method is "", then the Do method
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// will flush the output buffer and receive pending replies without sending a
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// command.
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//
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// Use the Send and Do methods to implement pipelined transactions.
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//
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// c.Send("MULTI")
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// c.Send("INCR", "foo")
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// c.Send("INCR", "bar")
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// r, err := c.Do("EXEC")
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// fmt.Println(r) // prints [1, 1]
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//
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// Concurrency
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//
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// Connections support one concurrent caller to the Receive method and one
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// concurrent caller to the Send and Flush methods. No other concurrency is
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// supported including concurrent calls to the Do and Close methods.
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//
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// For full concurrent access to Redis, use the thread-safe Pool to get, use
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// and release a connection from within a goroutine. Connections returned from
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// a Pool have the concurrency restrictions described in the previous
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// paragraph.
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//
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// Publish and Subscribe
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//
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// Use the Send, Flush and Receive methods to implement Pub/Sub subscribers.
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//
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// c.Send("SUBSCRIBE", "example")
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// c.Flush()
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// for {
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// reply, err := c.Receive()
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// if err != nil {
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// return err
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// }
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// // process pushed message
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// }
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//
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// The PubSubConn type wraps a Conn with convenience methods for implementing
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// subscribers. The Subscribe, PSubscribe, Unsubscribe and PUnsubscribe methods
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// send and flush a subscription management command. The receive method
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// converts a pushed message to convenient types for use in a type switch.
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//
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// psc := redis.PubSubConn{Conn: c}
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// psc.Subscribe("example")
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// for {
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// switch v := psc.Receive().(type) {
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// case redis.Message:
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// fmt.Printf("%s: message: %s\n", v.Channel, v.Data)
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// case redis.Subscription:
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// fmt.Printf("%s: %s %d\n", v.Channel, v.Kind, v.Count)
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// case error:
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// return v
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// }
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// }
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//
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// Reply Helpers
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//
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// The Bool, Int, Bytes, String, Strings and Values functions convert a reply
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// to a value of a specific type. To allow convenient wrapping of calls to the
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// connection Do and Receive methods, the functions take a second argument of
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// type error. If the error is non-nil, then the helper function returns the
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// error. If the error is nil, the function converts the reply to the specified
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// type:
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//
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// exists, err := redis.Bool(c.Do("EXISTS", "foo"))
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// if err != nil {
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// // handle error return from c.Do or type conversion error.
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// }
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//
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// The Scan function converts elements of a array reply to Go types:
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//
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// var value1 int
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// var value2 string
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// reply, err := redis.Values(c.Do("MGET", "key1", "key2"))
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// if err != nil {
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// // handle error
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// }
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// if _, err := redis.Scan(reply, &value1, &value2); err != nil {
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// // handle error
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// }
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//
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// Errors
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//
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// Connection methods return error replies from the server as type redis.Error.
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//
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// Call the connection Err() method to determine if the connection encountered
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// non-recoverable error such as a network error or protocol parsing error. If
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// Err() returns a non-nil value, then the connection is not usable and should
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// be closed.
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package redis
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