Module: SafeMemoize::ClassMethods

Defined in:
lib/safe_memoize/class_methods.rb

Overview

Class-level DSL added to any class that does +prepend SafeMemoize+.

Instance Method Summary collapse

Instance Method Details

#memoize(method_name, ttl: nil, max_size: nil, ttl_refresh: false, if: nil, unless: nil, shared: false, key: nil) ⇒ void

This method returns an undefined value.

Wraps an existing instance method with a thread-safe per-instance cache.

Must be called after the method is defined. Raises +ArgumentError+ immediately at class-definition time if no such method exists.

Examples:

Zero-argument method

def expensive_query = db.run("SELECT …")
memoize :expensive_query

With TTL and LRU cap

def fetch(id) = http_get(id)
memoize :fetch, ttl: 60, max_size: 500

Conditional — only cache successful responses

memoize :fetch, if: ->(v) { v[:status] == 200 }

Parameters:

  • method_name (Symbol, String) —

    name of the instance method to memoize

  • ttl (Numeric, nil) (defaults to: nil) —

    seconds until the cached value expires; +nil+ means the entry never expires. Falls back to SafeMemoize::Configuration#default_ttl when +nil+.

  • max_size (Integer, nil) (defaults to: nil) —

    maximum number of cached entries per instance for this method; the least-recently-used entry is evicted when the limit is reached. Falls back to SafeMemoize::Configuration#default_max_size when +nil+.

  • ttl_refresh (Boolean) (defaults to: false) —

    when +true+, every cache hit resets the expiry clock (sliding-window TTL). Requires +ttl:+ to be set.

  • if (Proc, nil) (defaults to: nil) —

    callable predicate; the result is cached only when the predicate returns truthy. Receives the computed return value as its argument.

  • unless (Proc, nil) (defaults to: nil) —

    inverse of +:if+; the result is not cached when the predicate returns truthy.

  • shared (Boolean) (defaults to: false) —

    when +true+, results are stored on the class rather than per instance — all instances share one cache.

  • key (Proc, nil) (defaults to: nil) —

    class-level custom cache key generator. Receives the same arguments as the method and should return a single comparable value. Instance-level keys set via PublicCustomKeyMethods#memoize_with_custom_key take priority.

Raises:

  • (ArgumentError) —

    if the method does not exist, or option values are invalid



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# File 'lib/safe_memoize/class_methods.rb', line 41

def memoize(method_name, ttl: nil, max_size: nil, ttl_refresh: false, if: nil, unless: nil, shared: false, key: nil)
  method_name = method_name.to_sym

  unless method_defined?(method_name) || private_method_defined?(method_name) || protected_method_defined?(method_name)
    raise ArgumentError, "cannot memoize :#{method_name} — no instance method with that name is defined on #{self}"
  end

  visibility = memoized_method_visibility(method_name)

  config = SafeMemoize.configuration
  ttl = config.default_ttl if ttl.nil?
  max_size = config.default_max_size if max_size.nil?

  # :if and :unless are reserved Ruby keywords, so they can't be referenced
  # as local variables directly. binding.local_variable_get is the only way
  # to read keyword arguments with those names inside the method body.
  cond_if = binding.local_variable_get(:if)
  cond_unless = binding.local_variable_get(:unless)

  ttl = if ttl.nil?
    nil
  else

    ttl = Float(ttl)
    raise ArgumentError, "ttl must be non-negative" if ttl < 0

    ttl
  end

  max_size = if max_size.nil?
    nil
  else
    raise ArgumentError, "max_size must be a positive integer" unless max_size.is_a?(Integer)
    raise ArgumentError, "max_size must be positive" unless max_size > 0

    max_size
  end

  raise ArgumentError, "ttl_refresh: requires a ttl: to be set" if ttl_refresh && ttl.nil?

  if cond_if && cond_unless
    raise ArgumentError, "cannot specify both :if and :unless"
  end
  raise ArgumentError, ":if must be callable" if cond_if && !cond_if.respond_to?(:call)
  raise ArgumentError, ":unless must be callable" if cond_unless && !cond_unless.respond_to?(:call)
  raise ArgumentError, ":key must be callable" if key && !key.respond_to?(:call)

  __safe_memo_class_key_generators__[method_name] = key if key

  # Normalize to a single "should cache?" predicate
  condition = if cond_if
    cond_if
  elsif cond_unless
    ->(result) { !cond_unless.call(result) }
  end

  if shared
    klass = self
    shared_mutex = klass.send(:__safe_memo_shared_mutex__)

    mod = Module.new do
      define_method(method_name) do |*args, **kwargs, &block|
        return super(*args, **kwargs, &block) if block

        cache_key = compute_cache_key(method_name, args, kwargs)

        shared_mutex.synchronize do
          shared_cache = klass.send(:__safe_memo_shared_cache__)
          record = shared_cache[cache_key]
          now = Process.clock_gettime(Process::CLOCK_MONOTONIC)
          record_live = record && (record[:expires_at].nil? || record[:expires_at] > now)

          if record_live
            if max_size
              lru = klass.send(:__safe_memo_shared_lru_order__)[method_name] ||= {}
              lru.delete(cache_key)
              lru[cache_key] = true
            end
            record[:expires_at] = memo_expires_at(ttl) if ttl_refresh
            record_cache_hit(method_name, args, kwargs)
            call_memo_hooks(:on_hit, cache_key, record)
            record[:value]
          else
            call_memo_hooks(:on_expire, cache_key, record) if record && !record_live

            start_time = Process.clock_gettime(Process::CLOCK_MONOTONIC)
            value = Adapters::OpenTelemetry.trace(SafeMemoize.configuration.opentelemetry_tracer, method_name, klass.name) { super(*args, **kwargs) }
            elapsed_time = Process.clock_gettime(Process::CLOCK_MONOTONIC) - start_time

            new_record = memo_record(value, expires_at: memo_expires_at(ttl))

            if !condition || condition.call(value)
              if max_size
                lru = klass.send(:__safe_memo_shared_lru_order__)[method_name] ||= {}
                lru.delete_if { |key, _| !shared_cache.key?(key) }
                if lru.size >= max_size
                  lru_key = lru.keys.first
                  lru.delete(lru_key)
                  evicted = shared_cache.delete(lru_key)
                  call_memo_hooks(:on_evict, lru_key, evicted) if evicted
                end
              end
              shared_cache[cache_key] = new_record
              if max_size
                lru = klass.send(:__safe_memo_shared_lru_order__)[method_name] ||= {}
                lru[cache_key] = true
              end
              call_memo_hooks(:on_store, cache_key, new_record)
            end

            record_cache_miss(method_name, args, kwargs, elapsed_time)
            call_memo_hooks(:on_miss, cache_key, new_record)

            value
          end
        end
      end

      send(visibility, method_name)
    end

    prepend mod

    return
  end

  mod = Module.new do
    define_method(method_name) do |*args, **kwargs, &block|
      # Blocks bypass cache entirely — they aren't comparable
      return super(*args, **kwargs, &block) if block

      cache_key = compute_cache_key(method_name, args, kwargs)

      if max_size || condition || ttl_refresh
        # Locked path: used when LRU tracking, conditional storage, or TTL refresh is needed.
        memo_mutex!.synchronize do
          record = memo_cache_record(cache_key)
          if record
            lru_touch(method_name, cache_key) if max_size
            record[:expires_at] = memo_expires_at(ttl) if ttl_refresh
            record_cache_hit(method_name, args, kwargs)
            call_memo_hooks(:on_hit, cache_key, record)
            memo_record_value(record)
          else
            start_time = Process.clock_gettime(Process::CLOCK_MONOTONIC)
            value = Adapters::OpenTelemetry.trace(SafeMemoize.configuration.opentelemetry_tracer, method_name, self.class.name) { super(*args, **kwargs) }
            elapsed_time = Process.clock_gettime(Process::CLOCK_MONOTONIC) - start_time

            new_record = memo_record(value, expires_at: memo_expires_at(ttl))
            if !condition || condition.call(value)
              lru_evict_if_over_limit(method_name, max_size) if max_size
              @__safe_memo_cache__ ||= {}
              @__safe_memo_cache__[cache_key] = new_record
              lru_touch(method_name, cache_key) if max_size
              call_memo_hooks(:on_store, cache_key, new_record)
            end
            record_cache_miss(method_name, args, kwargs, elapsed_time)
            call_memo_hooks(:on_miss, cache_key, new_record)

            value
          end
        end
      else
        # Fast path: check without lock
        if (record = memo_cache_record(cache_key))
          record_cache_hit(method_name, args, kwargs)
          call_memo_hooks(:on_hit, cache_key, record)
          return memo_record_value(record)
        end

        # Cache miss - compute and store
        start_time = Process.clock_gettime(Process::CLOCK_MONOTONIC)
        result = memo_fetch_or_store(cache_key, ttl: ttl) do
          Adapters::OpenTelemetry.trace(SafeMemoize.configuration.opentelemetry_tracer, method_name, self.class.name) { super(*args, **kwargs) }
        end
        elapsed_time = Process.clock_gettime(Process::CLOCK_MONOTONIC) - start_time

        with_memo_lock do
          record_cache_miss(method_name, args, kwargs, elapsed_time)
          new_record = memo_cache_record(cache_key)
          call_memo_hooks(:on_store, cache_key, new_record)
          call_memo_hooks(:on_miss, cache_key, new_record)
        end

        result
      end
    end

    send(visibility, method_name)
  end

  prepend mod
end

#memoize_all(except: [], only: [], include_protected: false, include_private: false, **options) ⇒ void

This method returns an undefined value.

Memoizes every eligible public instance method defined directly on the class.

Accepts all options that #memoize accepts, plus +:except:+ and +:only:+. Raises +ArgumentError+ when both +:only:+ and +:except:+ are given.

Parameters:

  • except (Array<Symbol, String>) (defaults to: []) —

    method names to skip

  • only (Array<Symbol, String>) (defaults to: []) —

    when non-empty, only these methods are memoized

  • include_protected (Boolean) (defaults to: false) —

    also memoize +protected+ methods

  • include_private (Boolean) (defaults to: false) —

    also memoize +private+ methods

  • options (Hash) —

    any additional options forwarded to #memoize

Raises:

  • (ArgumentError) —

    if both +:only:+ and +:except:+ are given



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# File 'lib/safe_memoize/class_methods.rb', line 247

def memoize_all(except: [], only: [], include_protected: false, include_private: false, **options)
  raise ArgumentError, "cannot specify both :only and :except" if only.any? && except.any?

  excluded = Array(except).map(&:to_sym)
  included = Array(only).map(&:to_sym)

  methods = public_instance_methods(false)
  methods |= protected_instance_methods(false) if include_protected
  methods |= private_instance_methods(false) if include_private

  methods.each do |method_name|
    next if excluded.include?(method_name)
    next if included.any? && !included.include?(method_name)

    memoize(method_name, **options)
  end
end

#reset_all_shared_memos ⇒ void

This method returns an undefined value.

Clears the entire class-level shared cache for this class.



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# File 'lib/safe_memoize/class_methods.rb', line 291

def reset_all_shared_memos
  __safe_memo_shared_mutex__.synchronize do
    @__safe_memo_shared_cache__ = {}
    @__safe_memo_shared_lru_order__ = {}
  end
end

#reset_shared_memo(method_name, *args, **kwargs) ⇒ void

This method returns an undefined value.

Clears one or all entries from the class-level shared cache.

With no positional args after +method_name+, clears all shared entries for that method. With args/kwargs, clears only the matching entry.

Parameters:

  • method_name (Symbol, String) —

    the memoized method

  • args (Array) —

    positional arguments identifying the entry to clear

  • kwargs (Hash) —

    keyword arguments identifying the entry to clear



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# File 'lib/safe_memoize/class_methods.rb', line 274

def reset_shared_memo(method_name, *args, **kwargs)
  method_name = method_name.to_sym
  specific_key = (args.empty? && kwargs.empty?) ? nil : [method_name, args, kwargs]

  __safe_memo_shared_mutex__.synchronize do
    if specific_key
      __safe_memo_shared_cache__.delete(specific_key)
      __safe_memo_shared_lru_order__[method_name]&.delete(specific_key)
    else
      __safe_memo_shared_cache__.delete_if { |key, _| key[0] == method_name }
      __safe_memo_shared_lru_order__.delete(method_name)
    end
  end
end

#shared_memo_age(method_name, *args, **kwargs) ⇒ Float?

Returns how many seconds ago the shared entry was cached, or +nil+ if not cached or already expired.

Parameters:

  • method_name (Symbol, String)
  • args (Array)
  • kwargs (Hash)

Returns:

  • (Float, nil) 


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# File 'lib/safe_memoize/class_methods.rb', line 340

def shared_memo_age(method_name, *args, **kwargs)
  method_name = method_name.to_sym
  cache_key = [method_name, args, kwargs]

  __safe_memo_shared_mutex__.synchronize do
    cache = @__safe_memo_shared_cache__
    return nil unless cache

    record = cache[cache_key]
    return nil unless record

    now = Process.clock_gettime(Process::CLOCK_MONOTONIC)
    return nil if record[:expires_at] && record[:expires_at] <= now

    cached_at = record[:cached_at]
    return nil unless cached_at

    (now - cached_at).round(6)
  end
end

#shared_memo_count(method_name = nil) ⇒ Integer

Returns the number of live entries in the class-level shared cache.

Parameters:

  • method_name (Symbol, String, nil) (defaults to: nil) —

    when given, counts only entries for that method; when +nil+, counts all methods.

Returns:

  • (Integer) 


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# File 'lib/safe_memoize/class_methods.rb', line 324

def shared_memo_count(method_name = nil)
  __safe_memo_shared_mutex__.synchronize do
    cache = @__safe_memo_shared_cache__ || {}
    now = Process.clock_gettime(Process::CLOCK_MONOTONIC)
    live = cache.reject { |_, r| r[:expires_at] && r[:expires_at] <= now }
    method_name ? live.count { |key, _| key[0] == method_name.to_sym } : live.count
  end
end

#shared_memo_stale?(method_name, *args, **kwargs) ⇒ Boolean

Returns +true+ if the shared entry exists but its TTL has elapsed.

Parameters:

  • method_name (Symbol, String)
  • args (Array)
  • kwargs (Hash)

Returns:

  • (Boolean) 


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# File 'lib/safe_memoize/class_methods.rb', line 367

def shared_memo_stale?(method_name, *args, **kwargs)
  method_name = method_name.to_sym
  cache_key = [method_name, args, kwargs]

  __safe_memo_shared_mutex__.synchronize do
    cache = @__safe_memo_shared_cache__
    return false unless cache

    record = cache[cache_key]
    return false unless record

    expires_at = record[:expires_at]
    return false unless expires_at

    expires_at <= Process.clock_gettime(Process::CLOCK_MONOTONIC)
  end
end

#shared_memoized?(method_name, *args, **kwargs) ⇒ Boolean

Returns +true+ if a live shared cache entry exists for the given call signature.

Parameters:

  • method_name (Symbol, String)
  • args (Array) —

    positional arguments

  • kwargs (Hash) —

    keyword arguments

Returns:

  • (Boolean) 


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# File 'lib/safe_memoize/class_methods.rb', line 304

def shared_memoized?(method_name, *args, **kwargs)
  method_name = method_name.to_sym
  cache_key = [method_name, args, kwargs]

  __safe_memo_shared_mutex__.synchronize do
    cache = @__safe_memo_shared_cache__
    return false unless cache

    record = cache[cache_key]
    return false unless record

    record[:expires_at].nil? || record[:expires_at] > Process.clock_gettime(Process::CLOCK_MONOTONIC)
  end
end