单页web应用:javascript从前端到后端（源码）

redis - a node.js redis client =========================== This is a complete Redis client for node.js. It supports all Redis commands, including many recently added commands like EVAL from experimental Redis server branches. Install with: npm install redis Pieter Noordhuis has provided a binding to the official `hiredis` C library, which is non-blocking and fast. To use `hiredis`, do: npm install hiredis redis If `hiredis` is installed, `node_redis` will use it by default. Otherwise, a pure JavaScript parser will be used. If you use `hiredis`, be sure to rebuild it whenever you upgrade your version of node. There are mysterious failures that can happen between node and native code modules after a node upgrade. ## Usage Simple example, included as `examples/simple.js`: ```js var redis = require("redis"), client = redis.createClient(); // if you'd like to select database 3, instead of 0 (default), call // client.select(3, function() { /* ... */ }); client.on("error", function (err) { console.log("Error " + err); }); client.set("string key", "string val", redis.print); client.hset("hash key", "hashtest 1", "some value", redis.print); client.hset(["hash key", "hashtest 2", "some other value"], redis.print); client.hkeys("hash key", function (err, replies) { console.log(replies.length + " replies:"); replies.forEach(function (reply, i) { console.log(" " + i + ": " + reply); }); client.quit(); }); ``` This will display: mjr:~/work/node_redis (master)$ node example.js Reply: OK Reply: 0 Reply: 0 2 replies: 0: hashtest 1 1: hashtest 2 mjr:~/work/node_redis (master)$ ## Performance Here are typical results of `multi_bench.js` which is similar to `redis-benchmark` from the Redis distribution. It uses 50 concurrent connections with no pipelining. JavaScript parser: PING: 20000 ops 42283.30 ops/sec 0/5/1.182 SET: 20000 ops 32948.93 ops/sec 1/7/1.515 GET: 20000 ops 28694.40 ops/sec 0/9/1.740 INCR: 20000 ops 39370.08 ops/sec 0/8/1.269 LPUSH: 20000 ops 36429.87 ops/sec 0/8/1.370 LRANGE (10 elements): 20000 ops 9891.20 ops/sec 1/9/5.048 LRANGE (100 elements): 20000 ops 1384.56 ops/sec 10/91/36.072 hiredis parser: PING: 20000 ops 46189.38 ops/sec 1/4/1.082 SET: 20000 ops 41237.11 ops/sec 0/6/1.210 GET: 20000 ops 39682.54 ops/sec 1/7/1.257 INCR: 20000 ops 40080.16 ops/sec 0/8/1.242 LPUSH: 20000 ops 41152.26 ops/sec 0/3/1.212 LRANGE (10 elements): 20000 ops 36563.07 ops/sec 1/8/1.363 LRANGE (100 elements): 20000 ops 21834.06 ops/sec 0/9/2.287 The performance of `node_redis` improves dramatically with pipelining, which happens automatically in most normal programs. ### Sending Commands Each Redis command is exposed as a function on the `client` object. All functions take either an `args` Array plus optional `callback` Function or a variable number of individual arguments followed by an optional callback. Here is an example of passing an array of arguments and a callback: client.mset(["test keys 1", "test val 1", "test keys 2", "test val 2"], function (err, res) {}); Here is that same call in the second style: client.mset("test keys 1", "test val 1", "test keys 2", "test val 2", function (err, res) {}); Note that in either form the `callback` is optional: client.set("some key", "some val"); client.set(["some other key", "some val"]); If the key is missing, reply will be null (probably): client.get("missingkey", function(err, reply) { // reply is null when the key is missing console.log(reply); }); For a list of Redis commands, see [Redis Command Reference](http://redis.io/commands) The commands can be specified in uppercase or lowercase for convenience. `client.get()` is the same as `client.GET()`. Minimal parsing is done on the replies. Commands that return a single line reply return JavaScript Strings, integer replies return JavaScript Numbers, "bulk" replies return node Buffers, and "multi bulk" replies return a JavaScript Array of node Buffers. `HGETALL` returns an Object with Buffers keyed by the hash keys. # API ## Connection Events `client` will emit some events about the state of the connection to the Redis server. ### "ready" `client` will emit `ready` a connection is established to the Redis server and the server reports that it is ready to receive commands. Commands issued before the `ready` event are queued, then replayed just before this event is emitted. ### "connect" `client` will emit `connect` at the same time as it emits `ready` unless `client.options.no_ready_check` is set. If this options is set, `connect` will be emitted when the stream is connected, and then you are free to try to send commands. ### "error" `client` will emit `error` when encountering an error connecting to the Redis server. Note that "error" is a special event type in node. If there are no listeners for an "error" event, node will exit. This is usually what you want, but it can lead to some cryptic error messages like this: mjr:~/work/node_redis (master)$ node example.js node.js:50 throw e; ^ Error: ECONNREFUSED, Connection refused at IOWatcher.callback (net:870:22) at node.js:607:9 Not very useful in diagnosing the problem, but if your program isn't ready to handle this, it is probably the right thing to just exit. `client` will also emit `error` if an exception is thrown inside of `node_redis` for whatever reason. It would be nice to distinguish these two cases. ### "end" `client` will emit `end` when an established Redis server connection has closed. ### "drain" `client` will emit `drain` when the TCP connection to the Redis server has been buffering, but is now writable. This event can be used to stream commands in to Redis and adapt to backpressure. Right now, you need to check `client.command_queue.length` to decide when to reduce your send rate. Then you can resume sending when you get `drain`. ### "idle" `client` will emit `idle` when there are no outstanding commands that are awaiting a response. ## redis.createClient(port, host, options) Create a new client connection. `port` defaults to `6379` and `host` defaults to `127.0.0.1`. If you have `redis-server` running on the same computer as node, then the defaults for port and host are probably fine. `options` in an object with the following possible properties: * `parser`: which Redis protocol reply parser to use. Defaults to `hiredis` if that module is installed. This may also be set to `javascript`. * `return_buffers`: defaults to `false`. If set to `true`, then all replies will be sent to callbacks as node Buffer objects instead of JavaScript Strings. * `detect_buffers`: default to `false`. If set to `true`, then replies will be sent to callbacks as node Buffer objects if any of the input arguments to the original command were Buffer objects. This option lets you switch between Buffers and Strings on a per-command basis, whereas `return_buffers` applies to every command on a client. * `socket_nodelay`: defaults to `true`. Whether to call setNoDelay() on the TCP stream, which disables the Nagle algorithm on the underlying socket. Setting this option to `false` can result in additional throughput at the cost of more latency. Most applications will want this set to `true`. * `no_ready_check`: defaults to `false`. When a connection is established to the Redis server, the server might still be loading the database from disk. While loading, the server not respond to any commands. To work around this, `node_redis` has a "ready check" which sends the `INFO` command to the server. The response from the `INFO` command indicates whether the server is ready for more commands. When ready, `node_redis` emits a `ready` event. Setting `no_ready_check` to `true` wil