Class: RSX::Cache::Memory

Inherits:
Object
  • Object
show all
Defined in:
lib/rsx/cache.rb

Overview

Thread-safe in-process LRU. This is the default store so caching works with no configuration and no dependencies.

Constant Summary collapse

DEFAULT_MAX_ENTRIES = 
4096

Instance Method Summary collapse

Constructor Details

#initialize(max_entries: DEFAULT_MAX_ENTRIES) ⇒ Memory

Returns a new instance of Memory.



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# File 'lib/rsx/cache.rb', line 13

def initialize(max_entries: DEFAULT_MAX_ENTRIES)
  @max_entries = max_entries
  @entries = {}
  @lock = Mutex.new
end

Instance Method Details

#clear ⇒ Object 



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# File 'lib/rsx/cache.rb', line 56

def clear
  @lock.synchronize { @entries.clear }
  self
end

#delete(key) ⇒ Object 



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# File 'lib/rsx/cache.rb', line 52

def delete(key)
  @lock.synchronize { @entries.delete(key) }
end

#fetch(key, expires_in: nil) ⇒ Object 



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# File 'lib/rsx/cache.rb', line 19

def fetch(key, expires_in: nil)
  found = read(key)
  return found unless found.nil?

  write(key, yield, expires_in: expires_in)
end

#read(key) ⇒ Object 



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# File 'lib/rsx/cache.rb', line 26

def read(key)
  @lock.synchronize do
    value, expires_at = @entries[key]
    next nil if value.nil?

    if expires_at && expires_at < now
      @entries.delete(key)
      next nil
    end

    # Re-insert so the entry counts as most recently used.
    @entries.delete(key)
    @entries[key] = [value, expires_at]
    value
  end
end

#size ⇒ Object 



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# File 'lib/rsx/cache.rb', line 61

def size
  @lock.synchronize { @entries.size }
end

#write(key, value, expires_in: nil) ⇒ Object 



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# File 'lib/rsx/cache.rb', line 43

def write(key, value, expires_in: nil)
  @lock.synchronize do
    @entries.delete(key)
    @entries[key] = [value, expires_in && (now + expires_in)]
    @entries.shift while @entries.size > @max_entries
  end
  value
end