redis-dart

Redis protocol parser and client It is designed to be fast and simple to use.

Curretly supported features:

  • raw commands - this enables sending any command as raw data
  • unicode - strings are UTF8 encoded swen sending and decoded when received
  • transactions for executing multiple commands in atomic way
  • pubsub helper for dispatcing messgaes trough single connection
  • performance - this counts as feture too

Simple

Redis protocol is coposition of array, strings(and bulk) and integers. For example executing command SET key value is no more that serializing array of strings ["SET","key","value"]. Cammands can be executed by

Future f = command.send_object(["SET","key","value"]);

This enables sending any command.

Fast

It can made 110K SET or GET operations per second - tested localy on my laptop with i5 proc and debian{https://www.debian.org/} OS, This is code that yields such result and can give you first impression

import 'package:redis/redis.dart';
main(){
  const int N = 200000;
  int start;
  RedisConnection conn = new RedisConnection();
  conn.connect('localhost',6379).then((Command command){
    print("test started, please wait ...");
    start =  new DateTime.now().millisecondsSinceEpoch;
    command.pipe_start();
    for(int i=1;i<N;i++){ 
      command.set("test $i","$i")
      .then((v){
        assert(v=="OK");
      });
    }
    //last command will be executed and then processed last
    command.set("test $N","$N").then((v){
      assert(v=="OK"); 
      double diff = (new DateTime.now().millisecondsSinceEpoch - start)/1000.0;
      double perf = N/diff;
      print("$N operations done in $diff s\nperformance $perf/s");
    });
    command.pipe_end();
  });
}

Transactions

Transactions are started by command MULTI and then complited with command EXEC. .multi() and .exec() and class Transaction are implemeted as additional helpers for checking result of each command executed during transation.

import 'package:redis/redis.dart';
...

RedisConnection conn = new RedisConnection();
conn.connect('localhost',6379).then((Command command){    
  command.multi().then((Transaction trans){
      trans.send_object(["SET","val","0"]);
      for(int i=0;i<200000;++i){
        trans.send_object(["INCR","val"]).then((v){
          assert(i==v);
        });
      }
      trans.send_object(["GET","val"]).then((v){
        print("number is now $v");
      });
      trans.exec();
  });
});

Take note here, that Future returned by trans.send_object() is executed after .exec() so make sure you dont try to call .exec() inside of such Future, becuase command will never complete.

Unicode

By default UTF8 encoding/decoding for string is used. Each string is coverted in binary array using UTF8 encoding. This makes ascii string compatible in both direction.

PubSub

There is little helper that enables dispatching recevied messages.

PSUBSCRIBE{http://redis.io/commands/PSUBSCRIBE} on messages a* and b* Subscription sub = command.psubscribe("a*","b*");

Subscription allows registering trough .add(String pattern,Function callback) Unlike redis rich pattern matching, this pattern allows only for optional * wildchar at the end of string.

  sub.add("abra*",(String chan,String message){
     print("on channel: $chan message: $message");
  });
  

Here is full example from test code.

import 'package:redis/redis.dart';
main(){
  RedisConnection conn1 = new RedisConnection();
  RedisConnection conn2 = new RedisConnection();
  Command cmd1;
  Command cmd2;
  Subscription sub;
  conn1.connect('localhost',6379)
  .then((Command cmd){
    cmd1 = cmd;
    return conn2.connect('localhost',6379);
  })
  .then((Command cmd){ 
    cmd2=cmd;
    sub = cmd2.psubscribe(["a*","b*"]);
    sub.add("*",(k,v){
      print("$k $v");
     });
  })
  .then((_){ 
    cmd1.send_object(["PUBLISH","aaa","aa"]);
    cmd1.send_object(["PUBLISH","bbb","bb"]);
    cmd1.send_object(["PUBLISH","ccc","cc"]); //we are not subscibed on this
  });
}

Todo

In near future

  • Better documentation
  • Implement all "generic comands" with named commands
  • Better error handling - that is ability to recover from error
  • Install spellchecker

Libraries

redis
test