Intro to Redis

What is Redis?• Redis is an open source, advanced key-value store. It is often referred to as a data

structure server since keys can contain strings, hashes, lists, sets and sorted sets.

http://redis.io

What is Jedis?• Redis recommended client is Jedis.

• Available at https://github.com/xetorthio/jedis/wiki/Getting-started

http://redis.io/clients git clone git://github.com/xetorthio/jedis.git

Maven dependency

<dependency> <groupId>redis.clients</groupId> <artifactId>jedis</artifactId> <version>2.0.0</version> <type>jar</type> <scope>compile</scope></dependency>

Setting up the Pool

private void setupPool(){ try{ pool = new JedisPool(new JedisPoolConfig(), HOST, PORT, poolTimeout) ; jedis = pool.getResource(); System.out.println("Redis Client is connection to: " + HOST + ":" + PORT) ; jedis.auth("foobared"); jedis.configSet("timeout", "500"); jedis.connect(); jedis.flushAll(); }catch(Exception ex){ ex.printStackTrace(); } }

InstallationDownload, extract and compile Redis with:$ wget http://redis.googlecode.com/files/redis-2.4.13.tar.gz$ tar xzf redis-2.4.13.tar.gz$ cd redis-2.4.13$ make

Basic Usage- Strings $ src/redis-cliredis> set foo barOKredis> get foo"bar"

Basic Usage- StringsAPPEND – Make a string longerGET – Fetch a string at keyGETRANGE – Fetch a substring of key's valueGETSET – Get and Set in one operationMGET – Multiple GetsMSET – Multiple SetsMSETNX – SET Multiple if Not eXistsSET – SET a value if not existsSETEX – SET a value that EXpiresSETNX – Set if Not eXistsSETRANGE – Rewrite a substringSTRLEN – Integer length of string

Basic Usage- More with Strings

INCR, INCRBY, DECR, DECRBY,

Atomic Counters!

Atomic operation - prevents anyother processor or I/O device fromwriting or reading memory untilthe operation is complete.

More with Strings

In fact, all of the built-incommands of Redis are atomic.

And they can be chained together(pipelined) to create complexatomic transactions.

Command Line Interface

Basic Usage – Keys

redis> keys b*1) "baz"2) "bar"

(Use sparingly, though; keys is expensive.)

Basic Usage - Listsredis> LPUSH mylist "world"(integer) 1redis> LPUSH mylist "hello"(integer) 2// [ 'world', 'hello' ]redis> LRANGE mylist 0 -11) "hello"2) "world"

public void lPushListTest(String queueName, String value){ try{ jedis.lpush(queueName, value) ; }catch(Exception ex){ ex.printStackTrace(); } }

public void lPopList(String queueName){ while(jedis.llen(queueName) != 0 ){ String item = jedis.lpop(queueName); } }

Basic Usage - Lists

LINDEX – Return the list item at a certain positionLINSERT – Insert item into list BEFORE|AFTER itemLLEN – Number of list items (length)LRANGE – Return some of the itemsLREM – Remove one or more itemsLSET – Sets the list element at index to valueLTRIM – Lop off some itemsLPOP, LPUSH, LPUSHX – Left pop/pushRPOP, RPUSH, RPUSHX, RPOPLPUSH – Right pop/pushBLPOP, BRPOP, BRPOPLPUSH – Blocking pop/push

Basic Usage - Setsredis>  SADD myset "Hello" (integer) 1

redis>  SADD myset "World" (integer) 1

redis>  SADD myset "World" (integer) 0

redis>  SMEMBERS myset 1) "World" 2) "Hello“

redis> 

public void sAdd(String key, String member) throws Exception { Jedis jedis = null; try{ jedis = (Jedis) getJedisInstance() ;jedis.sadd(key, member); }catch(Exception ex){ ex.printStackTrace(); }finally{ returnJedisInstance(jedis); getLog( getClass() ).logInfo("returnJedisInstance"); } }

Basic Usage - Sets

SADD – Add a member to a setSCARD – Set CARDinality – Number of set membersSDIFF – Calculate difference between 2 setsSDIFFSTORE – Store the Difference of 2 sets in a setSINTER – Calculate the intersection between 2 setsSINTERSTORE – Store the intersection of 2 sets in a setSISMEMBER – Bool test whether X is a member of set SSMEMBERS – list out all the membersSMOVE – Move a member from a set to another setSPOP – Pop a member off from a setSRANDMEMBER – Fetch a random set memberSREM – Remove a member from the setSUNION – Merge two sets togetherSUNIONSTORE – Store the merger of two sets in a set

Basic Usage - Hashesredis>  HMSET myhash field1 "Hello" field2 "World" OK

redis>  HGET myhash field1 "Hello“

redis>  HGET myhash field2 "World"

redis> 

public void hSetTest(String queueName, String key, String value){ try{ jedis.hsetnx(queueName, key, value) ; }catch(Exception ex){ ex.printStackTrace(); } }

Basic Usage - HashesHDEL – Delete a field & value from a hashHEXISTS – Bool test whether field is in hashHGET – fetch value stored under hash → fieldHGETALL – fetch the whole hashHINCRBY – Increment a value stored under a hash fieldHKEYS – keys as a set → array_keys( )HLEN – Integer – Number of fields stored in hashHMGET – Array – Fetch multiple fields from hashHMSET – Set multiple fields in a hashHSET – Set one field in a hashHSETNX – Set a hash field if it doesn't existHVALS – vals as a list → array_values( )

Basic Usage - Sorted Sets

public void zAdd(String key, Sting score, String member) throws Exception { Jedis jedis = null; try{ jedis = (Jedis) getJedisInstance() ;jedis.zadd(key, score, member); }catch(Exception ex){ ex.printStackTrace(); }finally{ returnJedisInstance(jedis); getLog( getClass() ).logInfo("returnJedisInstance"); } }

redis>  ZADD myzset 1 "one“ (integer) 1

redis>  ZADD myzset 1 "uno" (integer) 1

redis>  ZADD myzset 2 "two" (integer) 1

redis>  ZADD myzset 3 "two" (integer) 0

redis>  ZRANGE myzset 0 -1 WITHSCORES 1) "one“2) "1" 3) "uno" 4) "1" 5) "two" 6) "3"

redis> 

Basic Usage - Sorted SetsZADD – Add a member to a set with a scoreZCARD – Count how many members are in the sorted setZCOUNT – Count how many elemenents between 2 scoresZINCRBY – Increase/Decrease a member's scoreZINTERSTORE – Intersect on scores and store itZRANGE – Return some members between 2 indexesZRANGEBYSCORE – Return some members between 2 scoresZRANK – Returns a member index from Lo to HiZREM – Remove a sorted set's memberZREMRANGEBYRANK – Remove some members by rankZREMRANGEBYSCORE – Remove some members by scoreZREVRANGE – Fetch members by index in desc orderZREVRANGEBYSCORE – Fetch members by score in desc orderZREVRANK – Returns the index from Hi to LoZSCORE – Fetch the score of a memberZUNIONSTORE – Merge 2 sorted sets into a 3rd sorted set

Basic Usage- Pub/Sub

redis> subscribe fooReading messages... (press Ctrl-C to quit)1) "subscribe"2) “foo"3) (integer) 1

redis>

Basic Usage- Pub/Sub

redis> subscribe fooReading messages... (press Ctrl-C to quit)1) "subscribe"2) “foo"3) (integer) 1 1) "message"2) “foo"3) “test"

redis>publish foo test(integer) 1

Basic Usage- Pub/Sub

public void subscribeChannels(String channel1, String channel2){ try{ jedis.subscribe(this, channel1, channel2);System.out.println("sub.getSubscribedChannels();" + this.getSubscribedChannels()); }catch(Exception ex){ ex.printStackTrace(); } }

public void publishMessage(String channel, String message){ try{ jedis.publish(channel, message); }catch(Exception ex){ ex.printStackTrace(); }}

Utilities public void flushAllQueue(){ try{ jedis.flushAll(); jedis.flushDB(); }catch(Exception ex){ ex.printStackTrace(); } }

public void saveQueueToDisk(){ jedis.save(); }