Class: Mudis

Inherits:
Object
  • Object
show all
Extended by:
Expiry, LRU, Metrics, Namespace, Persistence
Defined in:
lib/mudis.rb,
lib/mudis/lru.rb,
lib/mudis/bound.rb,
lib/mudis/expiry.rb,
lib/mudis/metrics.rb,
lib/mudis/namespace.rb,
lib/mudis/persistence.rb

Overview

Mudis is a thread-safe, in-memory, sharded, LRU cache with optional compression and expiry. It is designed for high concurrency and performance within a Ruby application.

Defined Under Namespace

Modules: Expiry, LRU, Metrics, Namespace, Persistence Classes: Bound, LRUNode

Class Attribute Summary collapse

Class Method Summary collapse

Methods included from Persistence

install_persistence_hook!, load_snapshot!, save_snapshot!

Methods included from Metrics

metrics, reset_metrics!

Methods included from Namespace

clear_namespace, keys, with_namespace

Methods included from Expiry

cleanup_expired!, start_expiry_thread, stop_expiry_thread

Class Attribute Details

.compress ⇒ Object

Returns the value of attribute compress.



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# File 'lib/mudis.rb', line 40

def compress
  @compress
end

.default_ttl ⇒ Object

Returns the value of attribute default_ttl.



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# File 'lib/mudis.rb', line 40

def default_ttl
  @default_ttl
end

.eviction_threshold ⇒ Object

Returns the value of attribute eviction_threshold.



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# File 'lib/mudis.rb', line 40

def eviction_threshold
  @eviction_threshold
end

.hard_memory_limit ⇒ Object

Returns the value of attribute hard_memory_limit.



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# File 'lib/mudis.rb', line 40

def hard_memory_limit
  @hard_memory_limit
end

.max_bytes ⇒ Object

Returns the value of attribute max_bytes.



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# File 'lib/mudis.rb', line 41

def max_bytes
  @max_bytes
end

.max_ttl ⇒ Object

Returns the value of attribute max_ttl.



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# File 'lib/mudis.rb', line 40

def max_ttl
  @max_ttl
end

.max_value_bytes ⇒ Object

Returns the value of attribute max_value_bytes.



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# File 'lib/mudis.rb', line 41

def max_value_bytes
  @max_value_bytes
end

.serializer ⇒ Object

Returns the value of attribute serializer.



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# File 'lib/mudis.rb', line 40

def serializer
  @serializer
end

Class Method Details

.all_keys ⇒ Object

Returns an array of all cache keys



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# File 'lib/mudis.rb', line 389

def all_keys
  keys = []
  buckets.times do |idx|
    mutex = @mutexes[idx]
    store = @stores[idx]
    mutex.synchronize { keys.concat(store.keys) }
  end
  keys
end

.apply_config! ⇒ Object

Applies the current configuration to Mudis



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# File 'lib/mudis.rb', line 71

def apply_config! # rubocop:disable Metrics/AbcSize,Metrics/MethodLength
  validate_config!

  self.serializer = config.serializer
  self.compress = config.compress
  self.max_value_bytes = config.max_value_bytes
  self.hard_memory_limit = config.hard_memory_limit
  self.max_bytes = config.max_bytes
  self.eviction_threshold = config.eviction_threshold
  self.max_ttl = config.max_ttl
  self.default_ttl = config.default_ttl

  @persistence_enabled    = config.persistence_enabled
  @persistence_path       = config.persistence_path
  @persistence_format     = config.persistence_format
  @persistence_safe_write = config.persistence_safe_write

  if config.buckets
    @buckets = config.buckets
    reset!
  end

  return unless @persistence_enabled

  install_persistence_hook!
end

.bind(namespace:, default_ttl: nil, max_ttl: nil, max_value_bytes: nil) ⇒ Object 



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# File 'lib/mudis.rb', line 61

def bind(namespace:, default_ttl: nil, max_ttl: nil, max_value_bytes: nil)
  Bound.new(
    namespace: namespace,
    default_ttl: default_ttl,
    max_ttl: max_ttl,
    max_value_bytes: max_value_bytes
  )
end

.bucket_index(key) ⇒ Object

Computes which bucket a key belongs to



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# File 'lib/mudis.rb', line 188

def bucket_index(key)
  key.hash % buckets
end

.buckets ⇒ Object

Number of cache buckets (shards). Default: 32

Raises:

  • (ArgumentError) 


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# File 'lib/mudis.rb', line 159

def self.buckets
  return @buckets if @buckets

  val = config.buckets || ENV["MUDIS_BUCKETS"]&.to_i || 32
  raise ArgumentError, "bucket count must be > 0" if val <= 0

  @buckets = val
end

.clear(key, namespace: nil) ⇒ Object

Clears a specific key from the cache, a semantic synonym for delete This method is provided for clarity in usage It behaves the same as delete



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# File 'lib/mudis.rb', line 352

def clear(key, namespace: nil)
  delete(key, namespace: namespace)
end

.config ⇒ Object

Returns the current configuration object



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# File 'lib/mudis.rb', line 57

def config
  @config ||= MudisConfig.new
end

.configure ⇒ Object

Configures Mudis with a block, allowing customization of settings



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# File 'lib/mudis.rb', line 44

def configure
  new_config = config.dup
  yield(new_config)

  old_config = @config
  @config = new_config
  apply_config!
rescue StandardError
  @config = old_config
  raise
end

.current_memory_bytes ⇒ Object

Returns total memory used across all buckets



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# File 'lib/mudis.rb', line 418

def current_memory_bytes
  @current_bytes.sum
end

.delete(*a, **k) ⇒ Object

rubocop:disable Naming/MethodParameterName,Style/GlobalVars



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# File 'lib/mudis.rb', line 326

def delete(key, namespace: nil)
  key = namespaced_key(key, namespace)
  idx = bucket_index(key)
  mutex = @mutexes[idx]

  mutex.synchronize do
    evict_key(idx, key)
  end
end

.exists?(key, namespace: nil) ⇒ Boolean

Checks if a key exists and is not expired

Returns:

  • (Boolean) 


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# File 'lib/mudis.rb', line 193

def exists?(key, namespace: nil)
  !!read(key, namespace: namespace)
end

.fetch(*a, **k, &b) ⇒ Object

rubocop:disable Naming/MethodParameterName,Style/GlobalVars



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# File 'lib/mudis.rb', line 340

def fetch(key, expires_in: nil, force: false, namespace: nil, singleflight: false) # rubocop:disable Metrics/MethodLength
  return fetch_without_lock(key, expires_in:, force:, namespace:) { yield } unless singleflight

  lock_key = namespaced_key(key, namespace)
  with_inflight_lock(lock_key) do
    fetch_without_lock(key, expires_in:, force:, namespace:) { yield }
  end
end

.inspect(key, namespace: nil) ⇒ Object

Inspects a key and returns all meta data for it



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# File 'lib/mudis.rb', line 367

def inspect(key, namespace: nil) # rubocop:disable Metrics/MethodLength
  key = namespaced_key(key, namespace)
  idx = bucket_index(key)
  store = @stores[idx]
  mutex = @mutexes[idx]

  mutex.synchronize do
    entry = store[key]
    return nil unless entry

    {
      key: key,
      bucket: idx,
      expires_at: entry[:expires_at],
      created_at: entry[:created_at],
      size_bytes: key.bytesize + entry[:value].bytesize,
      compressed: compress
    }
  end
end

.least_touched(n = 10) ⇒ Object

Returns the least-touched keys across all buckets



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# File 'lib/mudis.rb', line 400

def least_touched(n = 10) # rubocop:disable Metrics/MethodLength,Naming/MethodParameterName
  keys_with_touches = []

  buckets.times do |idx|
    mutex = @mutexes[idx]
    store = @stores[idx]

    mutex.synchronize do
      store.each do |key, entry|
        keys_with_touches << [key, entry[:touches] || 0]
      end
    end
  end

  keys_with_touches.sort_by { |_, count| count }.first(n)
end

.max_memory_bytes ⇒ Object

Returns configured maximum memory allowed



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# File 'lib/mudis.rb', line 423

def max_memory_bytes
  @max_bytes
end

.metrics ⇒ Object

rubocop:disable Style/GlobalVars



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# File 'lib/mudis_proxy.rb', line 34

def metrics = $mudis.metrics # rubocop:disable Style/GlobalVars

.read(*a, **k) ⇒ Object

rubocop:disable Naming/MethodParameterName,Style/GlobalVars



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# File 'lib/mudis.rb', line 198

def read(key, namespace: nil) # rubocop:disable Metrics/MethodLength,Metrics/AbcSize,Metrics/CyclomaticComplexity,Metrics/PerceivedComplexity
  key = namespaced_key(key, namespace)
  ns = namespace || Thread.current[:mudis_namespace]
  raw_entry = nil
  idx = bucket_index(key)
  mutex = @mutexes[idx]
  store = @stores[idx]

  mutex.synchronize do
    raw_entry = @stores[idx][key]
    if raw_entry && raw_entry[:expires_at] && Time.now > raw_entry[:expires_at]
      evict_key(idx, key)
      raw_entry = nil
    end

    if store[key]
      store[key][:touches] = (store[key][:touches] || 0) + 1
      promote_lru(idx, key)
    end

    metric(:hits, namespace: ns) if raw_entry
    metric(:misses, namespace: ns) unless raw_entry
  end

  return nil unless raw_entry

  decompress_and_deserialize(raw_entry[:value])
end

.replace(key, value, expires_in: nil, namespace: nil) ⇒ Object

Replaces the value for a key if it exists, otherwise does nothing This is useful for updating values without needing to check existence first It will write the new value and update the expiration if provided If the key does not exist, it will not create a new entry



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# File 'lib/mudis.rb', line 360

def replace(key, value, expires_in: nil, namespace: nil)
  return unless exists?(key, namespace: namespace)

  write(key, value, expires_in: expires_in, namespace: namespace)
end

.reset! ⇒ Object

rubocop:disable Style/GlobalVars



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# File 'lib/mudis.rb', line 116

def reset!
  stop_expiry_thread

  @buckets = nil
  b = buckets

  @stores        = Array.new(b) { {} }
  @mutexes       = Array.new(b) { Mutex.new }
  @lru_heads     = Array.new(b) { nil }
  @lru_tails     = Array.new(b) { nil }
  @lru_nodes     = Array.new(b) { {} }
  @current_bytes = Array.new(b, 0)
  @inflight_mutexes = {}

  reset_metrics!
end

.reset_metrics! ⇒ Object

rubocop:disable Style/GlobalVars



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# File 'lib/mudis_proxy.rb', line 35

def reset_metrics! = $mudis.reset_metrics! # rubocop:disable Style/GlobalVars

.update(key, namespace: nil) ⇒ Object

Atomically updates the value for a key using a block



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# File 'lib/mudis.rb', line 272

def update(key, namespace: nil) # rubocop:disable Metrics/AbcSize,Metrics/MethodLength
  key = namespaced_key(key, namespace)
  idx = bucket_index(key)
  mutex = @mutexes[idx]
  store = @stores[idx]

  raw_entry = nil
  mutex.synchronize do
    raw_entry = store[key]
    return nil unless raw_entry
  end

  value = decompress_and_deserialize(raw_entry[:value])
  new_value = yield(value)
  new_raw = serializer.dump(new_value)
  new_raw = Zlib::Deflate.deflate(new_raw) if compress
  return if max_value_bytes && new_raw.bytesize > max_value_bytes

  mutex.synchronize do
    current_entry = store[key]
    return nil unless current_entry

    old_size = key.bytesize + current_entry[:value].bytesize
    new_size = key.bytesize + new_raw.bytesize

    ns = current_entry[:namespace]

    if hard_memory_limit && (current_memory_bytes - old_size + new_size) > max_memory_bytes
      metric(:rejected, namespace: ns)
      return
    end

    while (@current_bytes[idx] - old_size + new_size) > (@threshold_bytes / buckets) && @lru_tails[idx]
      break if @lru_tails[idx].key == key

      evict_key_name = @lru_tails[idx].key
      evict_ns = store[evict_key_name] && store[evict_key_name][:namespace]
      evict_key(idx, evict_key_name)
      metric(:evictions, namespace: evict_ns)
    end

    store[key][:value] = new_raw

    # Refresh TTL on update. If no TTL applies, keep existing expiry (possibly nil).
    now = Time.now
    ttl = current_entry[:expires_at] ? (current_entry[:expires_at] - current_entry[:created_at]) : nil
    store[key][:created_at] = now
    store[key][:expires_at] = ttl ? now + ttl : nil
    @current_bytes[idx] += (new_size - old_size)
    promote_lru(idx, key)
  end
end

.validate_config! ⇒ Object

Validates the current configuration, raising errors for invalid settings

Raises:

  • (ArgumentError) 


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# File 'lib/mudis.rb', line 99

def validate_config! # rubocop:disable Metrics/AbcSize,Metrics/CyclomaticComplexity,Metrics/PerceivedComplexity
  if config.max_value_bytes && config.max_value_bytes > config.max_bytes
    raise ArgumentError,
          "max_value_bytes cannot exceed max_bytes"
  end

  raise ArgumentError, "max_value_bytes must be > 0" if config.max_value_bytes && config.max_value_bytes <= 0

  raise ArgumentError, "buckets must be > 0" if config.buckets && config.buckets <= 0
  if config.eviction_threshold && (config.eviction_threshold <= 0 || config.eviction_threshold > 1)
    raise ArgumentError, "eviction_threshold must be > 0 and <= 1"
  end
  raise ArgumentError, "max_ttl must be > 0" if config.max_ttl && config.max_ttl <= 0
  raise ArgumentError, "default_ttl must be > 0" if config.default_ttl && config.default_ttl <= 0
end

.write(*a, **k) ⇒ Object

rubocop:disable Naming/MethodParameterName,Style/GlobalVars



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# File 'lib/mudis.rb', line 228

def write(key, value, expires_in: nil, namespace: nil) # rubocop:disable Metrics/MethodLength,Metrics/CyclomaticComplexity,Metrics/AbcSize,Metrics/PerceivedComplexity
  key = namespaced_key(key, namespace)
  ns = namespace || Thread.current[:mudis_namespace]
  raw = serializer.dump(value)
  raw = Zlib::Deflate.deflate(raw) if compress
  size = key.bytesize + raw.bytesize
  return if max_value_bytes && raw.bytesize > max_value_bytes

  if hard_memory_limit && current_memory_bytes + size > max_memory_bytes
    metric(:rejected, namespace: ns)
    return
  end

  # Ensure expires_in respects max_ttl and default_ttl
  expires_in = effective_ttl(expires_in)

  idx = bucket_index(key)
  mutex = @mutexes[idx]
  store = @stores[idx]

  mutex.synchronize do
    evict_key(idx, key) if store[key]

    while @current_bytes[idx] + size > (@threshold_bytes / buckets) && @lru_tails[idx]
      evict_key_name = @lru_tails[idx].key
      evict_ns = store[evict_key_name] && store[evict_key_name][:namespace]
      evict_key(idx, evict_key_name)
      metric(:evictions, namespace: evict_ns)
    end

    store[key] = {
      value: raw,
      expires_at: expires_in ? Time.now + expires_in : nil,
      created_at: Time.now,
      touches: 0,
      namespace: ns
    }

    insert_lru(idx, key)
    @current_bytes[idx] += size
  end
end