zavenarra/couchbase-ruby-client

Couchbase Ruby client library (official) built atop Fauna

Couchbase Ruby Client

This is the official client library for use with Couchbase Server.

INSTALL

This gem depends on a couple of external libraries to work with JSON and Couchbase Server. For JSON it uses yajl-ruby which is built atop yajl. For Couchbase iteraction it uses libcouchbase. The first dependency shouldn't cause any issues because it will bundle yajl in the c extensions. To install yajl-ruby use following command:

$ gem install yajl-ruby

In most cases installing libcouchbase is just as simple.

MacOS (Homebrew)

$ brew install libcouchbase

Or if our pull request isn't yet merged:

$ brew install http://packages.couchbase.com/clients/c/homebrew/libvbucket.rb
$ brew install http://packages.couchbase.com/clients/c/homebrew/libcouchbase.rb

Debian (Ubuntu)

Download packages depending on your architecture:

$ wget http://packages.couchbase.com/clients/c/libvbucket{1,1-dbg,-dev}_1.8.0.1-1_amd64.deb
$ wget http://packages.couchbase.com/clients/c/libcouchbase{1,1-dbg,-dev}_1.0.0-1_amd64.deb

or

$ wget http://packages.couchbase.com/clients/c/libvbucket{1,1-dbg,-dev}_1.8.0.1-1_i386.deb
$ wget http://packages.couchbase.com/clients/c/libcouchbase{1,1-dbg,-dev}_1.0.0-1_i386.deb

Then install them using dpkg tool

$ sudo dpkg -i lib{vbucket,couchbase}*.deb

Centos (Redhat and rpm-based systems)

Download packages depending on your architecture:

$ wget http://packages.couchbase.com/clients/c/libvbucket{1,-debuginfo,-devel}-1.8.0.1-1.x86_64.rpm
$ wget http://packages.couchbase.com/clients/c/libcouchbase{1,-debuginfo,-devel}-1.0.0-1.x86_64.rpm

or

$ wget http://packages.couchbase.com/clients/c/libvbucket{1,-debuginfo,-devel}-1.8.0.1-1.i386.rpm
$ wget http://packages.couchbase.com/clients/c/libcouchbase{1,-debuginfo,-devel}-1.0.0-1.i386.rpm

Then install them using rpm tool

$ sudo rpm -ivh lib{vbucket,couchbase}*.rpm

Couchbase gem

Now install the couchbase gem itself

$ gem install couchbase

USAGE

First of all you need to load library:

require 'couchbase'

There are several ways to establish new connection to Couchbase Server. By default it uses the http://localhost:8091/pools/default/buckets/default as the endpoint. The client will automatically adjust configuration when the cluster will rebalance its nodes when nodes are added or deleted therefore this client is "smart".

c = Couchbase.new

This is equivalent to following forms:

c = Couchbase.new("http://localhost:8091/pools/default/buckets/default")
c = Couchbase.new("http://localhost:8091/pools/default")
c = Couchbase.new("http://localhost:8091")
c = Couchbase.new(:host => "localhost")
c = Couchbase.new(:host => "localhost", :port => 8091)
c = Couchbase.new(:pool => "default", :bucket => "default")

The hash parameters take precedence on string URL.

The library supports both synchronous and asynchronous mode. You can choose either using the :async option or attribute.

c = Couchbase.new(:async => true)
# ... asynchronous mode
c.async = false
# ... synchronous mode

In asynchronous mode all operations will return control to caller without blocking current thread. You can pass the block to method and it will be called with result when the operation will be completed. You need to run event loop when you scheduled your operations:

c = Couchbase.new(:async => true)
c.run do |conn|
  conn.get("foo") {|ret| puts ret.value}
  conn.set("bar", "baz")
end

The handlers could be nested

c.run do |conn|
  conn.get("foo") do |ret|
    conn.incr(ret.value, :initial => 0)
  end
end

The asynchronous callback receives instance of Couchbase::Result which responds to several methods to figure out what was happened:

• success?. Returns true if operation succed.

• error. Returns nil or exception object (subclass of Couchbase::Error::Base) if something went wrong.

• key

• value

• flags

• cas. The CAS version tag.

• node. Node address. It is used in flush and stats commands.

• operation. The symbol, representing an operation.

To handle global errors in async mode #on_error callback should be used. It can be set in following fashions:

c.on_error do |opcode, key, exc|
  ...
end

handler = lambda {|opcode, key, exc| ...}
c.on_error = handler

By default connection uses :quiet mode. This mean it won't raise exceptions when the given key is not exists:

c.get("missing-key")            #=> nil

It could be useful when you are trying to make you code a bit efficient by avoiding exception handling. (See #add and #replace operations). You can turn on these exception by passing :quiet => false when you are instantiating the connection or change corresponding attribute:

c.quiet = false
c.get("missing-key")            #=> raise Couchbase::Error::NotFound
c.get("missing-key", :quiet => true)    #=> nil

The library supports three different formats for representing values:

• :document (default) format supports most of ruby types which could be mapped to JSON data (hashes, arrays, string, numbers). A future version will be able to run map/reduce queries on the values in the document form (hashes)

• :marshal This format avoids any conversions to be applied to your data, but your data should be passed as String. This is useful for building custom algorithms or formats. For example to implement a set: http://dustin.github.com/2011/02/17/memcached-set.html

• :plain Use this format if you'd like to transparently serialize your ruby object with standard Marshal.dump and Marshal.load methods

The couchbase API is the superset of Memcached binary protocol, so you can use its operations.

Get

val = c.get("foo")
val, flags, cas = c.get("foo", :extended => true)

Get and touch

val = c.get("foo", :ttl => 10)

Get multiple values. In quiet mode will put nil values on missing positions:

vals = c.get("foo", "bar", "baz")
c.get("foo"){|val, key| ... }
c.get("foo", :extended => true){|val, key, flags, cas| ... }

Get multiple values with extended information. The result will represented by hash with tuples [value, flags, cas] as a value.

vals = c.get("foo", "bar", "baz", :extended => true)
vals.inspect    #=> {"baz"=>["3", 0, 4784582192793125888],
                     "foo"=>["1", 0, 8835713818674332672],
                     "bar"=>["2", 0, 10805929834096100352]}

Hash-like syntax

c["foo"]
c["foo", "bar", "baz"]
c["foo", {:extended => true}]
c["foo", :extended => true]         # for ruby 1.9.x only

Touch

c.touch("foo")                      # use :default_ttl
c.touch("foo", 10)
c.touch("foo", :ttl => 10)
c.touch("foo" => 10, "bar" => 20)
c.touch("foo" => 10, "bar" => 20){|key, success| ... }

Set

c.set("foo", "bar")
c.set("foo", "bar", :flags => 0x1000, :ttl => 30, :format => :plain)
c["foo"] = "bar"
c["foo", {:flags => 0x1000, :format => :plain}] = "bar"
c["foo", :flags => 0x1000] = "bar"  # for ruby 1.9.x only
c.set("foo", "bar", :cas => 8835713818674332672)
c.set("foo", "bar"){|cas, key, operation| ... }

Add

Add command will fail if the key already exists. It accepts the same options as set command above.

c.add("foo", "bar")
c.add("foo", "bar", :flags => 0x1000, :ttl => 30, :format => :plain)

Replace

The replace command will fail if the key already exists. It accepts the same options as set command above.

c.replace("foo", "bar")

Prepend/Append

These commands are meaningful when you are using the :plain value format, because the concatenation is performed by server which has no idea how to merge to JSON values or values in ruby Marshal format. You may receive an Couchbase::Error::ValueFormat error.

c.set("foo", "world")
c.append("foo", "!")
c.prepend("foo", "Hello, ")
c.get("foo")                    #=> "Hello, world!"

Increment/Decrement

These commands increment the value assigned to the key. It will raise Couchbase::Error::DeltaBadval if the delta or value is not a number.

c.set("foo", 1)
c.incr("foo")                   #=> 2
c.incr("foo", :delta => 2)      #=> 4
c.incr("foo", 4)                #=> 8
c.incr("foo", -1)               #=> 7
c.incr("foo", -100)             #=> 0
c.incr("foo"){|val, cas| ... }

c.set("foo", 10)
c.decr("foo", 1)                #=> 9
c.decr("foo", 100)              #=> 0
c.decr("foo"){|val, cas| ... }

c.incr("missing1", :initial => 10)      #=> 10
c.incr("missing1", :initial => 10)      #=> 11
c.incr("missing2", :create => true)     #=> 0
c.incr("missing2", :create => true)     #=> 1

Note that it isn't the same as increment/decrement in ruby, which is performed on client side with following set operation:

c["foo"] = 10
c["foo"] -= 20                  #=> -10

Delete

c.delete("foo")
c.delete("foo", :cas => 8835713818674332672)
c.delete("foo", 8835713818674332672)
c.delete{|key, success| ... }

Flush

Flush the items in the cluster.

c.flush
c.flush{|node, success| ... }

Stats

Return statistics from each node in the cluster

c.stats
c.stats{|node, key, value| ... }

The result is represented as a hash with the server node address as the key and stats as key-value pairs.

{
  "172.16.16.76:12008"=>
    {
      "threads"=>"4",
      "connection_structures"=>"22",
      "ep_max_txn_size"=>"10000",
      ...
    },
  "172.16.16.76:12000"=>
    {
      "threads"=>"4",
      "connection_structures"=>"447",
      "ep_max_txn_size"=>"10000",
      ...
    },
  ...
}