Class: Utopia::Session::LazyHash

Inherits:
Object
  • Object
show all
Defined in:
lib/utopia/session/lazy_hash.rb

Overview

A simple hash table which fetches it's values only when required.

Instance Method Summary collapse

Constructor Details

#initialize(&block) ⇒ LazyHash

Initialize a lazily loaded hash.



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# File 'lib/utopia/session/lazy_hash.rb', line 12

def initialize(&block)
	@changed = false
	@values = nil
	
	@loader = block
end

Instance Method Details

#[](key) ⇒ Object

Fetch a value by key, loading the hash if necessary.



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# File 'lib/utopia/session/lazy_hash.rb', line 22

def [] key
	load![key]
end

#[]=(key, value) ⇒ Object

Store a value by key.



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# File 'lib/utopia/session/lazy_hash.rb', line 30

def []= key, value
	values = load!
	
	if values[key] != value
		values[key] = value
		@changed = true
	end
	
	return value
end

#changed? ⇒ Boolean

Check whether any value has changed.

Returns:

  • (Boolean) 


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# File 'lib/utopia/session/lazy_hash.rb', line 61

def changed?
	@changed
end

#delete(key) ⇒ Object

Delete a value by key.



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# File 'lib/utopia/session/lazy_hash.rb', line 51

def delete(key)
	load!
	
	@changed = true if @values.include? key
	
	@values.delete(key)
end

#include?(key) ⇒ Boolean

Check whether the hash contains a key.

Returns:

  • (Boolean) 


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# File 'lib/utopia/session/lazy_hash.rb', line 44

def include?(key)
	load!.include?(key)
end

#loaded? ⇒ Boolean

Check whether the underlying values have been loaded.

Returns:

  • (Boolean) 


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# File 'lib/utopia/session/lazy_hash.rb', line 89

def loaded?
	!@values.nil?
end

#needs_update?(timeout = nil) ⇒ Boolean

Check whether the values should be persisted.

Returns:

  • (Boolean) 


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# File 'lib/utopia/session/lazy_hash.rb', line 96

def needs_update?(timeout = nil)
	# If data has changed, we need update:
	return true if @changed
	
	# We want to be careful here and not call load! which isn't cheap operation.
	if timeout and @values and updated_at = @values[:updated_at]
		# If the last update was too long ago, we need update:
		return true if updated_at < (now - timeout)
	end
	
	return false
end

#now ⇒ Object

The current time for session expiry and persistence.



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# File 'lib/utopia/session/lazy_hash.rb', line 67

def now
	Time.now.utc
end

#persist(timeout = nil) ⇒ Object

Persist the session values if they have changed or require updating.



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# File 'lib/utopia/session/lazy_hash.rb', line 75

def persist(timeout = nil)
	return unless needs_update?(timeout)
	
	values = load!
	updated_at = values[:updated_at] = now
	
	result = yield(values, updated_at)
	@changed = false
	
	return result
end