Moneta: A unified interface for key/value stores
Moneta provides a standard interface for interacting with various kinds of key/value stores. Moneta supports the well-known NoSQL and document based stores.
A short overview of the features:
- Supports a lot of backends with consistent behaviour (See below)
- Allows a full configuration of the serialization -> compression -> adapter stack using proxies (Similar to Rack middlewares)
- Configurable serialization via
Moneta::Transformer
proxy (Marshal/JSON/YAML and many more) - Configurable value compression via
Moneta::Transformer
proxy (Zlib, Snappy, LZMA, ...) - Configurable key transformation via
Moneta::Transformer
proxy
- Configurable serialization via
- Expiration for all stores (Added via proxy
Moneta::Expires
if not supported natively) - Atomic operations
- Atomic incrementation and decrementation for most stores (Method
#increment
and#decrement
) - Atomic creation of entries (Method
#create
) - Shared/distributed database-wide synchronization primitives
Moneta::Mutex
andMoneta::Semaphore
- Atomic incrementation and decrementation for most stores (Method
- Includes a simple pure-ruby key/value server (
Moneta::Server
) and client (Moneta::Adapters::Client
) - Integration with Rails, Rack/Rack-Cache, Sinatra, Padrino and Ramaze.
If you are not yet convinced, you might ask why? What are the goals of the project?
- Get people started quickly with key/value stores! Therefore all the adapters are included in the gem and you are ready to go. Tilt does the same for template languages.
- Make it easy to compare different key/value stores and benchmark them
- To hide a lot of different and maybe complex APIs behind one well-designed and simple Moneta API
- Give people a starting point or example code to start working with their favourite key/value store. Feel free to copy code, please mention Moneta then :)
- Create a reusable piece of code, since similar things are solved over and over again (Rails brings its own cache stores, and many frameworks do the same...)
Moneta is tested thoroughly using GitHub Actions.
Getting started
Install Moneta via Rubygems
$ gem install moneta
or add it to your Gemfile
gem 'moneta'
Now you are ready to go:
require 'moneta'
# Create a simple file store
store = Moneta.new(:File, dir: 'moneta')
# Store some entries
store['key'] = 'value'
# Read entry
store.key?('key') # returns true
store['key'] # returns 'value'
store.close
Links
- Source: http://github.com/moneta-rb/moneta
- Bugs: http://github.com/moneta-rb/moneta/issues
- Tests and benchmarks: https://github.com/moneta-rb/moneta/actions
- API documentation:
- Latest Gem: http://rubydoc.info/gems/moneta/frames
- GitHub main: http://rubydoc.info/github/moneta-rb/moneta/main/frames
- Changelog: https://github.com/moneta-rb/moneta/blob/main/CHANGES
In case you are wondering, Moneta uses Semantic Versioning since v1.0.0.
Supported backends
Out of the box, it supports the following backends. Use the backend name symbol in the Moneta constructor (e.g. Moneta.new(:Memory)
).
- Memory:
- In-memory store (
:Memory
) - LRU hash - prefer this over :Memory! (
:LRUHash
) - LocalMemCache (
:LocalMemCache
) - Memcached store (
:Memcached
,:MemcachedNative
and:MemcachedDalli
)
- In-memory store (
- Relational Databases:
- DataMapper (
:DataMapper
) - ActiveRecord (
:ActiveRecord
) - Sequel (
:Sequel
) - Sqlite3 (
:Sqlite
)
- DataMapper (
- Filesystem:
- Key/value databases:
- Berkeley DB using DBM interface or NDBM (Depends on Ruby environment) (
:DBM
) - Cassandra (
:Cassandra
) - Daybreak (
:Daybreak
) - GDBM (
:GDBM
) - HBase (
:HBase
) - LevelDB (
:LevelDB
) - LMDB (
:LMDB
) - Redis (
:Redis
) - Riak (
:Riak
) - SDBM (
:SDBM
) - KyotoCabinet (
:KyotoCabinet
) - TokyoCabinet (
:TokyoCabinet
) - TokyoTyrant (
:TokyoTyrant
) - Simple Samba database TDB (
:TDB
)
- Berkeley DB using DBM interface or NDBM (Depends on Ruby environment) (
- Document databases:
- Moneta network protocols:
- Moneta key/value client (
:Client
works withMoneta::Server
) - Moneta HTTP/REST client (
:RestClient
works withRack::MonetaRest
)
- Moneta key/value client (
- Other
- Fog cloud storage which supports Amazon S3, Rackspace, etc. (
:Fog
) - Storage which doesn't store anything (
:Null
)
- Fog cloud storage which supports Amazon S3, Rackspace, etc. (
Some of the backends are not exactly based on key/value stores, e.g. the relational ones. These are useful if you already use the corresponding backend in your application. You get a key/value store for free then without installing any additional services and you still have the possibility to upgrade to a real key/value store.
Backend feature matrix
NOTE: The backend matrix is much more readable on rubydoc.info than on github. Go there!
Adapter | Required gems | MRI support1 | JRuby support1 | Multi-thread safe2 | Multi-process safe3 | Atomic increment4 | Atomic create5 | Native expires6 | Persistent | Key Traversal | Bulk read7 | Bulk write8 | Description |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Persistent stores | |||||||||||||
Mongo | mongo | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | MongoDB database |
Redis | redis | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | Redis database |
ActiveRecord | activerecord | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✗ | ✓ | ✓ | ✓ | ✓ | ActiveRecord ORM |
File | - | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✗ | ✓ | ✓ | ✗ | ✗ | File store |
LMDB | lmdb | ✓ | ✗ | ✓ | ✓ | ✓ | ✓ | ✗ | ✓ | ✓ | ✓ | ✓ | Symas Lightning Memory-Mapped Database (LMDB) |
Sequel | sequel | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✗ | ✓ | ✓ | ✓ | ✓ | Sequel ORM |
TokyoTyrant | tokyotyrant or ruby-tokyotyrant | ✓ | ✓ | ✗ | ✓ | ✓ | ✓ | ✗ | ✓ | ✗ | ✓ | ✗ | TokyoTyrant database |
PStore | - | ✓ | ✗ | ✗ | ✓9 | ✓ | ✓ | ✗ | ✓ | ✓ | ✓ | ✓ | PStore store |
YAML | - | ✓ | ✓ | ✗ | ✓9 | ✓ | ✓ | ✗ | ✓ | ✓ | ✗ | ✗ | YAML store |
Sqlite | sqlite3 | ✓ | ✗ | ? | ✓9 | ✓ | ✓ | ✗ | ✓ | ✓ | ✓ | ✓ | Sqlite3 database |
Daybreak | daybreak | ✓ | ✓ | ✗ | ✓ | ✓ | ✓ | ✗ | ✓ | ✓ | ✗ | ✓ | Incredibly fast pure-ruby key/value store Daybreak |
DBM | - | ✓ | ✗ | ✗ | ✗ | ✓ | ✓ | ✗ | ✓ | ✓ | ✓ | ✓ | Berkeley DB using DBM interface or NDBM (Depends on Ruby environment) |
GDBM | ffi-gdbm on JRuby | ✓ | ✓ | ✗ | ✗ | ✓ | ✓ | ✗ | ✓ | ✓ | ✓ | ✓ | GDBM database |
LevelDB | leveldb | ✓ | ✗ | ✗ | ✗ | ✓ | ✓ | ✗ | ✓ | ✓ | ✓ | ✓ | LevelDB database |
SDBM | - | ✓ | ✗ | ✗ | ✗ | ✓ | ✓ | ✗ | ✓ | ✓ | ✓ | ✓ | SDBM database |
TDB | tdb | ✓ | ✗ | ✗ | ✗ | ✓ | ✓ | ✗ | ✓ | ✓ | ✗ | ✗ | TDB database |
KyotoCabinet | kyotocabinet-ruby or kyotocabinet-ruby-reanimated | ✓ | ✗ | ✗ | ✗ | ✓ | ✓ | ✗ | ✓ | ✓ | ✓ | ✓ | KyotoCabinet database |
TokyoCabinet | tokyocabinet | ✓ | ✗ | ✗ | ✗ | ✓ | ✓ | ✗ | ✓ | ✓ | ✗ | ✗ | TokyoCabinet database |
DataMapper | dm-core, dm-migrations | ✓ | ✗ | ✓ | ✓ | ✗ | ✓ | ✗ | ✓ | ✗ | ✗ | ✗ | DataMapper ORM |
Couch | faraday, multi_json | ✓ | ✓ | ✗ | ✓ | ✗ | ✓ | ✗ | ✓ | ✓ | ✓ | ✓ | CouchDB database |
HBase | hbaserb | ✗ | ✗ | ? | ✓ | ✓ | ✗ | ✗ | ✓ | ✗ | ✗ | ✗ | HBase database |
Cassandra | cassandra | ✓ | ✓ | ? | ✓ | ✗ | ✗ | ✓ | ✓ | ✓ | ✓ | ✓ | Cassandra distributed database |
LocalMemCache | localmemcache | ✓ | ✗ | ✓ | ✓ | ✗ | ✗ | ✗ | ✓ | ✗ | ✗ | ✗ | LocalMemCache database |
Fog | fog | ✓ | ✓ | ? | ✓ | ✗ | ✗ | ✗ | ✓ | ✗ | ✗ | ✗ | Fog cloud store |
Riak | riak-client | ✗ | ✗ | ✗ | ✓ | ✗ | ✗ | ✗ | ✓ | ✗ | ✗ | ✗ | Riak database |
Non-persistent stores | |||||||||||||
MemcachedDalli | dalli | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✗10 | ✗ | ✓ | ✓ | Memcached database with Dalli library |
Memcached | dalli or memcached | ✓ | ?11 | ?11 | ✓ | ✓ | ✓ | ✓ | ✗10 | ✗ | ?11 | ?11 | Memcached database |
MemcachedNative | memcached | ✓ | ✗ | ✗ | ✓ | ✓ | ✓ | ✓ | ✗10 | ✗ | ✗ | ✗ | Memcached database with native library |
Cookie | - | ✓ | ✓ | ✗ | ✓12 | ✓ | ✓ | ✓ | ✗ | ✓ | ✗ | ✗ | Cookie in memory store |
LRUHash | - | ✓ | ✓ | ✗ | ✓12 | ✓ | ✓ | ✗ | ✗ | ✓ | ✗ | ✗ | LRU memory store |
Memory | - | ✓ | ✓ | ✗ | ✓12 | ✓ | ✓ | ✗ | ✗ | ✓ | ✓ | ✓ | Memory store |
Null | - | ✓ | ✓ | ✓ | ✓ | ✗ | ✗ | ✗ | ✗ | ✗ | ✗ | ✗ | No database |
Network clients | |||||||||||||
Client | - | ✓ | ✓ | ✗ | ✓ | ?13 | ?13 | ?13 | ?13 | ?13 | ✗ | ✗ | Moneta client adapter |
RestClient | - | ✓ | ✓ | ✗ | ✓ | ✗ | ✗ | ✗ | ?13 | ✗ | ✗ | ✗ | Moneta REST client adapter |
- Indicates that the adapter is expected to work on this platform. Most adapters will at least work on MRI, but some are curently considered unstable, in which case they are not supported on any platform.
- Make adapters thread-safe by using
Moneta::Lock
or by passing the optionthreadsafe: true
toMoneta#new
. There is alsoMoneta::Pool
which can be used to share a store between multiple threads if the store is multi-process safe. I recommend to add the option:threadsafe
to ensure thread-safety since for example under JRuby and Rubinius even the basic datastructures are not thread safe due to the lack of a global interpreter lock (GIL). This differs from MRI where some adapters might appear thread safe already but only due to the GIL. - Share a Moneta store between multiple processes using
Moneta::Shared
(See below). - If a store provides atomic increment it can be used with
Moneta::Semaphore
. You can add weak#increment
support using theMoneta::WeakIncrement
proxy. - If a store provides atomic creation it can be used with
Moneta::Mutex
. You can add weak#create
support using theMoneta::WeakCreate
proxy. - Add expiration support by using
Moneta::Expires
or by passing the optionexpires: true
toMoneta#new
. - This indicates that there is some performance gain when fetching multiple values at once using
#values_at
/#fetch_values
or#slice
. For instance, theMGET
instruction in Redis, or the ability to retrieve several rows in one query in SQL. - This indicates that there is some performance gain when storing multiple key/value pairs at once using
#merge!
/#update
. - Sqlite/YAML/PStore are multiprocess safe, but the performance suffers badly since the whole database file must be locked for writing. Use a key/value server if you want multiprocess concurrency!
- There are some servers which use the memcached protocol but which are persistent (e.g. MemcacheDB, Kai, IronCache, Roma, Flare and Kumofs)
- This feature is only available if the dalli backend is selected
- Store is multi-process safe because it is an in-memory store, values are not shared between multiple processes
- Depends on server
Proxies
In addition it supports proxies (Similar to Rack middlewares) which add additional features to storage backends:
Moneta::Proxy
andMoneta::Wrapper
are the proxy base classes.Moneta::Cache
combine two stores, one as backend and one as cache (e.g.Moneta::Adapters::File
+Moneta::Adapters::LRUHash
). Add it in the builder usinguse(:Cache) {}
.Moneta::Expires
to add expiration support to stores which don't support it natively. Add it in the builder usinguse :Expires
.Moneta::Fallback
use a store as a fallback when exceptions occur (by default the:Null
adapter is used so that an error results in a no-op). Add it to the builder usinguse(:Fallback, rescue: IOError)
Moneta::Lock
to make store thread safe. Add it in the builder usinguse :Lock
.Moneta::Logger
to log database accesses. Add it in the builder usinguse :Logger
.Moneta::Pool
to create a pool of stores as a means of making the store thread safe. Add it in the builder usinguse(:Pool, min: 2, max: 4, ttl: 60, timeout: 5) {}
.Moneta::Shared
to share a store between multiple processes. Add it in the builder usinguse(:Shared) {}
.Moneta::Stack
to stack multiple stores (Read returns result from first where the key is found, writes go to all stores). Add it in the builder usinguse(:Stack) {}
.Moneta::Transformer
transforms keys and values (Marshal, YAML, JSON, Base64, MD5, ...). Add it in the builder usinguse :Transformer
.Moneta::WeakIncrement
andMoneta::WeakCreate
to add#create
and#increment
support without atomicity (weak) to stores which don't support it.Moneta::WeakEachKey
to add key traversal to stores that don't support it, with the important caveat that only those keys previously seen by this proxy will be traversed.
Check the YARD documentation for more information and examples.
Serializers and compressors (Moneta::Transformer
)
Supported serializers:
- BEncode (
:bencode
) - BERT (
:bert
) - BSON (
:bson
) - JSON (
:json
) - Marshal (
:marshal
) - MessagePack (
:msgpack
) - Ox (
:ox
) - PHP (
:php
) - TNetStrings (
:tnet
) - YAML (
:yaml
)
Supported value compressors:
- Bzip2 (
:bzip2
) - LZ4 (
:lz4
) - LZMA (
:lzma
) - LZO (
:lzo
) - Snappy (
:snappy
) - QuickLZ (
:quicklz
) - Zlib (
:zlib
)
Supported encoders:
- Base64 (RFC 2045;
:base64
) - URL-safe Base64 (RFC 4648;
:urlsafe_base64
) - Url escape (
:escape
) - Hexadecimal (
:hex
) - QP (
:qp
) - UUEncode (
:uuencode
)
Special transformers:
- Digests (MD5, Shas, CityHash, ...)
- Add prefix to keys (
:prefix
) - HMAC to verify values (
:hmac
, useful forRack::MonetaCookies
)
Moneta API
The Moneta API is purposely extremely similar to the Hash API with a few minor additions. Every method takes also a optional option hash. In order so support an identical API across stores, Moneta does not support partial matches.
#initialize(options) options differs per-store, and is used to set up the store.
#[](key) retrieve a key. If the key is not available, return nil.
#load(key, options = {}) retrieve a key. If the key is not available, return nil.
#fetch(key, options = {}, &block) retrieve a key. If the key is not available, execute the
block and return its return value.
#fetch(key, value, options = {}) retrieve a key. If the key is not available, return the value,
#[]=(key, value) set a value for a key. If the key is already used, clobber it.
keys set using []= will never expire.
#store(key, value, options = {}) same as []=, but you can supply options.
#delete(key, options = {}) delete the key from the store and return the current value.
#key?(key, options = {}) true if the key exists, false if it does not.
#increment(key, amount = 1, options = {}) increment numeric value. This is an atomic operation
which is not supported by all stores. Returns current value.
#decrement(key, amount = 1, options = {}) increment numeric value. This is an atomic operation
which is not supported by all stores. Returns current value.
This is just syntactic sugar for incrementing with a negative value.
#create(key, value, options = {}) create entry. This is an atomic operation which is not supported by all stores.
Returns true if the value was created.
#values_at(*keys, **options) retrieve multiple keys. Returns an array of equal length to the keys.
Each entry in the array is either the value corresponding to the key
in the same position, or nil if the key is not available.
#fetch_values(*keys, **options, &block) retrieve multiple keys. Return is identical to values_at, except that
when a block is given it will be called once for each key that is not
available, and the return value of the block will be used in place of
nil in the array.
#slice(*keys, **options) retrieve multiple keys. Returns an enumerable of key-value pairs,
one for each of the supplied keys that is present in the store.
#merge!(pairs, options = {}) set values for multiple keys. "pairs" must be an enumerable of
key-value pairs to be stored. Any existing keys will be clobbered.
#merge!(pairs, options = {}, &block) set values for multiple keys. For each existing key, execute the block
passing the key, existing value and new value, and store the return
value.
#update(pairs, options = {}, &block) same as merge!
#each_key return an enumerable which will yield all keys in the store, one at a
time. This method is present if and only if the store supports the
:each_key feature.
#each_key(&block) yield all keys in the store to the block, one at a time. Again, this
method is present if and only if the store supports the :each_key
feature.
#clear(options = {}) clear all keys in this store.
#close close database connection.
#features return array of features, e.g. [:create, :expires, :increment]
#supports?(feature) returns true if store supports a given feature
Creating a Store
There is a simple interface to create a store using Moneta.new
. You will
get automatic key and value serialization which is provided by Moneta::Transformer
.
This allows you to store arbitrary Ruby objects. You can tune some options
when you call Moneta.new
. However for very fine tuning use Moneta.build
.
store = Moneta.new(:Memcached, server: 'localhost:11211')
store['key'] = 'value'
store['hash_key'] = {a: 1, b: 2}
store['object_key'] = MarshallableRubyObject.new
If you want to have control over the proxies, you have to use Moneta.build
:
store = Moneta.build do
# Adds expires proxy
use :Expires
# Transform key using Marshal and Base64 and value using Marshal
use :Transformer, key: [:marshal, :base64], value: :marshal
# IMPORTANT: adapter must be defined last for the builder to function properly.
# Memory backend
adapter :Memory
end
You can also directly access the underlying adapters if you don't want to use the Moneta stack.
db = Moneta::Adapters::File.new(dir: 'directory')
db['key'] = {a: 1, b: 2} # This will fail since you can only store Strings
# However for Mongo and Couch this works
# The hash will be mapped directly to a Mongo/Couch document.
db = Moneta::Adapters::Couch.new
db['key'] = {a: 1, b: 2}
db = Moneta::Adapters::Mongo.new
db['key'] = {a: 1, b: 2}
Expiration
The Cassandra, Memcached, Redis and Mongo backends support expiration natively.
cache = Moneta::Adapters::Memcached.new
# Or using the builder...
cache = Moneta.build do
adapter :Memcached
end
# Expires in 60 seconds
cache.store(key, value, expires: 60)
# Never expire
cache.store(key, value, expires: 0)
cache.store(key, value, expires: false)
# Update expires time if value is found
cache.load(key, expires: 30)
cache.key?(key, expires: 30)
# Or remove the expiration if found
cache.load(key, expires: false)
cache.key?(key, expires: 0)
You can add the expires feature to other backends using the Moneta::Expires
proxy. But be aware
that expired values are not deleted automatically if they are not looked up.
# Using the :expires option
cache = Moneta.new(:File, dir: '...', expires: true)
# or manually by using the proxy...
cache = Moneta::Expires.new(Moneta::Adapters::File.new(dir: '...'))
# or using the builder...
cache = Moneta.build do
use :Expires
adapter :File, dir: '...'
end
Key traversal
Where supported by the store's backend, it is possible to traverse the keys in
the store using the #each_key
method. Support for this can be tested by
calling store.supports?(:each_key)
, or checking for the presence of
:each_key
in store.features
.
store.each_key # returns an Enumerable
store.each_key do |key|
store.load(key) # read operations are supported within the block
store[key] = "x" # behaviour of write operations is undefined
end
Atomic operations
Atomic incrementation and raw access
The stores support the #increment
which allows atomic increments of unsigned integer values. If you increment
a non existing value, it will be created. If you increment a non integer value an exception will be raised.
store.increment('counter') # returns 1, counter created
store.increment('counter') # returns 2
store.increment('counter', -1) # returns 1
store.increment('counter', 13) # returns 14
store.increment('counter', 0) # returns 14
store.decrement('counter') # returns 13
store['name'] = 'Moneta'
store.increment('name') # raises an Exception
If you want to access the counter value you have to use raw access to the datastore. This is only important
if you have a Moneta::Transformer
somewhere in your proxy stack which transforms the values e.g. with Marshal
.
store.increment('counter') # returns 1, counter created
store.load('counter', raw: true) # returns 1
store.store('counter', '10', raw: true)
store.increment('counter') # returns 11
Fortunately there is a nicer way to do this using some syntactic sugar!
store.increment('counter') # returns 1, counter created
store.raw['counter'] # returns 1
store.raw.load('counter') # returns 1
store.raw['counter'] = '10'
store.increment('counter') # returns 11
You can also keep the raw
store in a variable and use it like this:
counters = store.raw
counters.increment('counter') # returns 1, counter created
counters['counter'] # returns 1
counters.load('counter') # returns 1
counters['counter'] = '10'
counters.increment('counter') # returns 11
Atomic create
The stores support the #create
which allows atomic creation of entries. #create
returns true
if the value was created.
store.create('key', 'value') # returns true
store.create('key', 'other value') # returns false
Atomic bulk operations
All stores support storage and retrieval of multiple keys using
#values_at
/#fetch_values
/#slice
and #merge!
/#update
. Wherever
possible, these operations are performed atomically. When this is not possible,
the #load
and #store
methods are called once for each key.
store.merge!('key1' => 'value1', 'key2' => 'value2') # stores two keys
store.values_at('key1', 'key2', 'key3') # returns ['value1', 'value2', nil]
store.fetch('key1', 'key3') { |k| k + ' missing' } # returns ['key1', 'key3 missing']
store.slice('key1', 'key2', 'key3') # returns enumerable of ['key1', 'value1'], ['key2', 'value2']
store.merge!('key2' => 'new value2', 'key3' => 'value3') do |key, value, new_value|
[value, new_value].join('+')
end # stores "value3" and "value2+new value2"
Shared/distributed synchronization primitives
Moneta provides shared/distributed synchronization primitives which are shared database-wide between all clients.
Moneta::Mutex
allows a single thread to enter a critical section.
mutex = Moneta::Mutex.new(store, 'mutex_key')
mutex.synchronize do
mutex.locked? # returns true
# Synchronized access to counter
store['counter'] += 1
end
begin
mutex.lock
mutex.locked? # returns true
# ...
ensure
mutex.unlock
end
Moneta::Semaphore
allows max_concurrent
threads to enter a critical section.
semaphore = Moneta::Semaphore.new(store, 'semaphore_counter', max_concurrent)
semaphore.synchronize do
semaphore.locked? # returns true
# ...
end
begin
semaphore.enter
semaphore.locked? # returns true
# ...
ensure
semaphore.leave
end
Weak atomic operations
If an underlying adapter doesn't provide atomic #create
or #increment
and #decrement
you can
use the proxies Moneta::WeakIncrement
and Moneta::WeakCreate
to add support without atomicity.
But then you have to ensure that the store is not shared by multiple processes and thread-safety is
provided by Moneta::Lock
.
Syntactic sugar and option merger
For raw data access as described before the class Moneta::OptionMerger
is used. It works like this:
# All methods after 'with' get the options passed
store.with(raw: true).load('key')
# You can also specify the methods
store.with(raw: true, only: :load).load('key')
store.with(raw: true, except: [:key?, :increment]).load('key')
# Syntactic sugar for raw access
store.raw.load('key')
# Access substore where all keys get a prefix
substore = store.prefix('sub')
substore['key'] = 'value'
store['key'] # returns nil
store['subkey'] # returns 'value'
# Set expiration time for all keys
short_lived_store = store.expires(60)
short_lived_store['key'] = 'value'
Add proxies to existing store
You can add proxies to an existing store. This is useful if you want to compress only a few values for example.
compressed_store = store.with(prefix: 'compressed') do
use :Transformer, value: :zlib
end
store['key'] = 'this value will not be compressed'
compressed_store['key'] = 'value will be compressed'
Framework Integration
Inspired by redis-store there exist integration classes for Rails and Rack/Rack-Cache. You can also use all the Rack middlewares together with Rails and the Sinatra framework. There exist the following integration classes:
- Rack, Rails and Sinatra
Rack::Session::Moneta
is a Rack middleware to use Moneta for storing sessionsRack::MonetaStore
is a Rack middleware which places a Moneta store in the environment and enables per-request cachingRack::MonetaCookies
is a Rack middleware which uses Moneta to store cookiesRack::MonetaRest
is a Rack application which exposes a Moneta store via REST/HTTPRack::Cache::Moneta
provides meta and entity stores for Rack-Cache
- Rails
ActionDispatch::Session::MonetaStore
is a Rails middleware to use Moneta for storing sessionsActiveSupport::Cache::MonetaStore
is a Rails cache implementation which uses a Moneta store as backend
- Ramaze
Ramaze::Cache::Moneta
is integrated into the Ramaze project and allows Ramaze to use Moneta as caching store
- Padrino adopted Moneta to replace their cache stores in padrino-cache.
Rack
Session store
You can use Moneta as a Rack session store. Use it in your config.ru
like this:
require 'rack/session/moneta'
# Use only the adapter name
use Rack::Session::Moneta, store: :Redis
# Use Moneta.new
use Rack::Session::Moneta, store: Moneta.new(:Memory, expires: true)
# Set rack options
use Rack::Session::Moneta, key: 'rack.session',
domain: 'foo.com',
path: '/',
expire_after: 2592000,
store: Moneta.new(:Memory, expires: true)
# Use the Moneta builder
use Rack::Session::Moneta do
use :Expires
adapter :Memory
end
Moneta middleware
There is a simple middleware which places a Moneta store in the Rack environment at env['rack.moneta_store']
. It supports per-request
caching if you add the option cache: true
. Use it in your config.ru
like this:
require 'rack/moneta_store'
# Add Rack::MonetaStore somewhere in your rack stack
use Rack::MonetaStore, :Memory, cache: true
run lambda { |env|
env['rack.moneta_store'] # is a Moneta store with per-request caching
}
# Pass it a block like the one passed to Moneta.build
use Rack::MonetaStore do
use :Transformer, value: :zlib
adapter :Cookie
end
run lambda { |env|
env['rack.moneta_store'] # is a Moneta store without caching
}
REST server
If you want to expose your Moneta key/value store via HTTP, you can use the Rack/Moneta REST service. Use it in your config.ru
like this:
require 'rack/moneta_rest'
map '/moneta' do
run Rack::MonetaRest.new(:Memory)
end
# Or pass it a block like the one passed to Moneta.build
run Rack::MonetaRest.new do
use :Transformer, value: :zlib
adapter :Memory
end
Rack-Cache
You can use Moneta as a Rack-Cache store. Use it in your config.ru
like this:
require 'rack/cache/moneta'
use Rack::Cache,
metastore: 'moneta://Memory?expires=true',
entitystore: 'moneta://Memory?expires=true'
# Or used named Moneta stores
Rack::Cache::Moneta['named_metastore'] = Moneta.build do
use :Expires
adapter :Memory
end
use Rack::Cache,
metastore: 'moneta://named_metastore',
entity_store: 'moneta://named_entitystore'
Cookies
Use Moneta to store cookies in Rack. It uses the Moneta::Adapters::Cookie
. You might
wonder what the purpose of this store or Rack middleware is: It makes it possible
to use all the transformers on the cookies (e.g. :prefix
, :marshal
and :hmac
for value verification).
require 'rack/moneta_cookies'
use Rack::MonetaCookies, domain: 'example.com', path: '/path'
run lambda { |env|
req = Rack::Request.new(env)
req. #=> is now a Moneta store!
env['rack.request.cookie_hash'] #=> is now a Moneta store!
req.['key'] #=> retrieves 'key'
req.['key'] = 'value' #=> sets 'key'
req..delete('key') #=> removes 'key'
[200, {}, []]
}
Rails
Session store
Add the session store in your application configuration config/environments/*.rb
.
require 'action_dispatch/middleware/session/moneta_store'
# Only by adapter name
config.cache_store :moneta_store, store: :Memory
# Use Moneta.new
config.cache_store :moneta_store, store: Moneta.new(:Memory)
# Use the Moneta builder
config.cache_store :moneta_store, store: Moneta.build do
use :Expires
adapter :Memory
end
Cache store
Add the cache store in your application configuration config/environments/*.rb
. Unfortunately the
Moneta cache store doesn't support matchers. If you need these features use a different server-specific implementation.
require 'active_support/cache/moneta_store'
# Only by adapter name
config.cache_store :moneta_store, store: :Memory
# Use Moneta.new
config.cache_store :moneta_store, store: Moneta.new(:Memory)
# Use the Moneta builder
config.cache_store :moneta_store, store: Moneta.build do
use :Expires
adapter :Memory
end
Padrino
Padrino adopted Moneta to replace their cache stores in padrino-cache. You use it like this
# Global Padrino caching
# Don't forget the expires: [true, Integer] if you want expiration support!
Padrino.cache = Moneta.new(:Memory, expires: true)
# Application caching
# Don't forget the expires: [true, Integer] if you want expiration support!
set :cache, Moneta.new(:Memory, expires: true)
Advanced
Build your own key value server
You can use Moneta to build your own key/value server which is shared between
multiple processes. If you run the following code in two different processes,
they will share the same data which will also be persistet in the database shared.db
.
require 'moneta'
store = Moneta.build do
use :Transformer, key: :marshal, value: :marshal
use :Shared do
use :Cache do
cache do
adapter :LRUHash
end
backend do
adapter :GDBM, file: 'shared.db'
end
end
end
end
If you want to go further, you might want to take a look at Moneta::Server
and Moneta::Adapters::Client
which
are used by Moneta::Shared
and provide the networking communication. But be aware that they are experimental
and subjected to change. They provide an acceptable performance (for being ruby only), but don't have a stable protocol yet.
You might wonder why I didn't use DRb to implement server and client - in fact my first versions used it, but with much worse performance and it was real fun to implement the networking directly :) There is still much room for improvement and experiments, try EventMachine, try Kgio, ...
ToyStore ORM
If you want something more advanced to handle your objects and relations,
use John Nunemaker's ToyStore which works
together with Moneta. Assuming that Person
is a ToyStore::Object
you can
add persistence using Moneta as follows:
# Use the Moneta Redis backend
Person.adapter :memory, Moneta.new(:Redis)
Testing and Benchmarks
Testing is done using GitHub Actions. Currently we support MRI Ruby >= 2.4.0 (but not yet 3.x) and the JRuby >= 9.2.9.0. MRI 2.3.0 should mostly still work, but is no longer tested in CI.
~~Benchmarks for each store are done on Travis-CI for each build.~~ At the time of writing, benchmarks still need to be migrated from Travis to GitHub Actions. Take a look there to compare the speed of the different key value stores for different key/value sizes and size distributions. Feel free to add your own configurations! The impact of Moneta should be minimal since it is only a thin layer on top of the different stores.
How to contribute?
Always feel free to open an issue on https://github.com/moneta-rb/moneta/issues if something doesn't work as you expect it to work. Feedback is also very welcome!
My only request about patches is that you please try to test them before submitting.
Contribute an adapter
If you want support for another adapter you can at first at it to the list of missing adapters at https://github.com/moneta-rb/moneta/issues/16
If you choose to implement an adapter please also add tests. Please check also
if anything in .github/workflows
needs changes, for example if you need to
start additional services.
Check if the default settings in Moneta#new are appropriate for your adapter. If not specify a better one.
Don't forget to edit the README.md and the CHANGES.
Alternatives
- Horcrux: Used at github, supports batch operations but only Memcached backend
- ActiveSupport::Cache::Store: The Rails cache store abstraction
- ToyStore: ORM mapper for key/value stores
- ToyStore Adapter: Adapter to key/value stores used by ToyStore, Moneta can be used directly with the ToyStore Memory adapter
- Cache: Rubygem cache wraps Memcached and Redis
- Ramaze::Cache: Cache stores of the Ramaze framework with support for LocalMemCache, Memcached, Sequel, Redis, ...
Authors
- Daniel Mendler
- Hannes Georg
- Alastair Pharo
- Originally by Yehuda Katz and contributors