Class: ThrottleMachines::Storage::Memory

Inherits:
Base
  • Object
show all
Defined in:
lib/throttle_machines/storage/memory.rb

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Base

#with_timeout

Constructor Details

#initialize(options = {}) ⇒ Memory

Returns a new instance of Memory.



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# File 'lib/throttle_machines/storage/memory.rb', line 8

def initialize(options = {})
  super
  @counters = Concurrent::Hash.new
  @gcra_states = Concurrent::Hash.new
  @token_buckets = Concurrent::Hash.new

  # Use a striped lock pattern - pool of locks for fine-grained concurrency
  @lock_pool_size = options[:lock_pool_size] || 32
  @locks = Array.new(@lock_pool_size) { Concurrent::ReadWriteLock.new }

  # Background cleanup thread
  @cleanup_interval = options[:cleanup_interval] || 60
  @shutdown = false
  @cleanup_thread = start_cleanup_thread if options[:auto_cleanup] != false

  # Ensure cleanup on garbage collection
  ObjectSpace.define_finalizer(self, self.class.finalizer(@cleanup_thread))
end

Class Method Details

.finalizer(cleanup_thread) ⇒ Object 



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# File 'lib/throttle_machines/storage/memory.rb', line 27

def self.finalizer(cleanup_thread)
  proc { cleanup_thread&.kill }
end

Instance Method Details

#check_gcra_limit(key, emission_interval, delay_tolerance, ttl) ⇒ Object

GCRA operations (atomic simulation)



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# File 'lib/throttle_machines/storage/memory.rb', line 83

def check_gcra_limit(key, emission_interval, delay_tolerance, ttl)
  with_write_lock(key) do
    now = current_time
    state = @gcra_states[key] || { tat: 0.0 }

    tat = [state[:tat], now].max
    allow = tat - now <= delay_tolerance

    if allow
      new_tat = tat + emission_interval
      @gcra_states[key] = { tat: new_tat, expires_at: now + ttl }
    end

    {
      allowed: allow,
      retry_after: allow ? 0 : (tat - now - delay_tolerance),
      tat: tat
    }
  end
end

#check_token_bucket(key, capacity, refill_rate, ttl) ⇒ Object

Token bucket operations (atomic simulation)



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# File 'lib/throttle_machines/storage/memory.rb', line 121

def check_token_bucket(key, capacity, refill_rate, ttl)
  with_write_lock(key) do
    now = current_time
    bucket = @token_buckets[key] || { tokens: capacity, last_refill: now }

    # Refill tokens
    elapsed = now - bucket[:last_refill]
    tokens_to_add = elapsed * refill_rate
    bucket[:tokens] = [bucket[:tokens] + tokens_to_add, capacity].min
    bucket[:last_refill] = now

    # Check if we can consume a token
    if bucket[:tokens] >= 1
      bucket[:tokens] -= 1
      @token_buckets[key] = bucket.merge(expires_at: now + ttl)

      {
        allowed: true,
        retry_after: 0,
        tokens_remaining: bucket[:tokens].floor
      }
    else
      retry_after = (1 - bucket[:tokens]) / refill_rate

      {
        allowed: false,
        retry_after: retry_after,
        tokens_remaining: 0
      }
    end
  end
end

#clear(pattern = nil) ⇒ Object

Utility operations



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# File 'lib/throttle_machines/storage/memory.rb', line 185

def clear(pattern = nil)
  if pattern
    regex = Regexp.new(pattern.gsub('*', '.*'))

    # Clear matching keys from all stores
    [@counters, @gcra_states, @token_buckets].each do |store|
      store.each_key do |k|
        store.delete(k) if k&.match?(regex)
      end
    end
  else
    @counters.clear
    @gcra_states.clear
    @token_buckets.clear
  end
end

#get_counter(key, window) ⇒ Object 



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# File 'lib/throttle_machines/storage/memory.rb', line 53

def get_counter(key, window)
  window_key = "#{key}:#{window}"

  with_read_lock(window_key) do
    counter = @counters[window_key]
    return 0 unless counter
    return 0 if counter[:expires_at] <= current_time

    counter[:count]
  end
end

#get_counter_ttl(key, window) ⇒ Object 



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# File 'lib/throttle_machines/storage/memory.rb', line 65

def get_counter_ttl(key, window)
  window_key = "#{key}:#{window}"

  with_read_lock(window_key) do
    counter = @counters[window_key]
    return 0 unless counter

    ttl = counter[:expires_at] - current_time
    [ttl, 0].max
  end
end

#healthy? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/throttle_machines/storage/memory.rb', line 202

def healthy?
  true
end

#increment_counter(key, window, amount = 1) ⇒ Object

Rate limiting operations



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# File 'lib/throttle_machines/storage/memory.rb', line 32

def increment_counter(key, window, amount = 1)
  window_key = "#{key}:#{window}"

  with_write_lock(window_key) do
    now = current_time
    # Fetch fresh value inside the lock to ensure consistency
    counter = @counters[window_key]

    if counter.nil? || counter[:expires_at] <= now
      # Create or reset counter atomically
      new_count = amount
      @counters[window_key] = { count: new_count, expires_at: now + window }
    else
      # Increment existing counter atomically
      new_count = counter[:count] + amount
      @counters[window_key] = { count: new_count, expires_at: counter[:expires_at] }
    end
    new_count
  end
end

#peek_gcra_limit(key, _emission_interval, delay_tolerance) ⇒ Object 



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# File 'lib/throttle_machines/storage/memory.rb', line 104

def peek_gcra_limit(key, _emission_interval, delay_tolerance)
  with_read_lock(key) do
    now = current_time
    state = @gcra_states[key] || { tat: 0.0 }

    tat = [state[:tat], now].max
    allow = tat - now <= delay_tolerance

    {
      allowed: allow,
      retry_after: allow ? 0 : (tat - now - delay_tolerance),
      tat: tat
    }
  end
end

#peek_token_bucket(key, capacity, refill_rate) ⇒ Object 



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# File 'lib/throttle_machines/storage/memory.rb', line 154

def peek_token_bucket(key, capacity, refill_rate)
  with_read_lock(key) do
    now = current_time
    bucket = @token_buckets[key] || { tokens: capacity, last_refill: now }

    # Calculate tokens without modifying state
    elapsed = now - bucket[:last_refill]
    tokens_to_add = elapsed * refill_rate
    current_tokens = [bucket[:tokens] + tokens_to_add, capacity].min

    if current_tokens >= 1
      {
        allowed: true,
        retry_after: 0,
        tokens_remaining: (current_tokens - 1).floor
      }
    else
      retry_after = (1 - current_tokens) / refill_rate

      {
        allowed: false,
        retry_after: retry_after,
        tokens_remaining: 0
      }
    end
  end
end

#reset_counter(key, window) ⇒ Object 



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# File 'lib/throttle_machines/storage/memory.rb', line 77

def reset_counter(key, window)
  window_key = "#{key}:#{window}"
  with_write_lock(window_key) { @counters.delete(window_key) }
end

#shutdown ⇒ Object 



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# File 'lib/throttle_machines/storage/memory.rb', line 206

def shutdown
  @shutdown = true
  @cleanup_thread&.join(1) # Wait up to 1 second for graceful shutdown
  @cleanup_thread&.kill if @cleanup_thread&.alive?
  @cleanup_thread = nil
end