Class: Zache
- Inherits:
-
Object
- Object
- Zache
- Defined in:
- lib/zache.rb
Overview
It is a very simple thread-safe in-memory cache with an ability to expire keys automatically, when their lifetime is over. Use it like this:
require 'zache'
zache = Zache.new
# Expires in 5 minutes
v = zache.get(:count, lifetime: 5 * 60) { expensive() }
For more information read README file.
- Author
-
Yegor Bugayenko ([email protected])
- Copyright
-
Copyright © 2018-2023 Yegor Bugayenko
- License
-
MIT
Defined Under Namespace
Classes: Fake
Instance Method Summary collapse
-
#clean ⇒ Object
Remove keys that are expired.
-
#exists?(key, dirty: false) ⇒ Boolean
Checks whether the value exists in the cache by the provided key.
-
#expired?(key) ⇒ Boolean
Checks whether the key exists in the cache and is expired.
-
#get(key, lifetime: 2**32, dirty: false, &block) ⇒ Object
Gets the value from the cache by the provided key.
-
#initialize(sync: true, dirty: false) ⇒ Zache
constructor
Makes a new object of the cache.
-
#locked? ⇒ Boolean
Is cache currently locked doing something?.
-
#mtime(key) ⇒ Object
Returns the modification time of the key, if it exists.
-
#put(key, value, lifetime: 2**32) ⇒ Object
Put a value into the cache.
-
#remove(key) ⇒ Object
Removes the value from the hash, by the provied key.
-
#remove_all ⇒ Object
Remove all keys from the cache.
-
#remove_by ⇒ Object
Remove all keys that match the block.
-
#size ⇒ Object
Total number of keys currently in cache.
Constructor Details
#initialize(sync: true, dirty: false) ⇒ Zache
Makes a new object of the cache.
“sync” is whether the hash is thread-safe (‘true`) or not (`false`); it is recommended to leave this parameter untouched, unless you really know what you are doing.
If the dirty
argument is set to true
, a previously calculated result will be returned if it exists and is already expired.
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# File 'lib/zache.rb', line 77 def initialize(sync: true, dirty: false) @hash = {} @sync = sync @dirty = dirty @mutex = Mutex.new end |
Instance Method Details
#clean ⇒ Object
Remove keys that are expired.
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# File 'lib/zache.rb', line 179 def clean synchronized { @hash.delete_if { |_key, value| expired?(value) } } end |
#exists?(key, dirty: false) ⇒ Boolean
Checks whether the value exists in the cache by the provided key. Returns TRUE if the value is here. If the key is already expired in the hash, it will be removed by this method and the result will be FALSE.
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# File 'lib/zache.rb', line 119 def exists?(key, dirty: false) rec = @hash[key] if expired?(key) && !dirty && !@dirty @hash.delete(key) rec = nil end !rec.nil? end |
#expired?(key) ⇒ Boolean
Checks whether the key exists in the cache and is expired. If the key is absent FALSE is returned.
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# File 'lib/zache.rb', line 130 def expired?(key) rec = @hash[key] !rec.nil? && rec[:start] < Time.now - rec[:lifetime] end |
#get(key, lifetime: 2**32, dirty: false, &block) ⇒ Object
Gets the value from the cache by the provided key.
If the value is not found in the cache, it will be calculated via the provided block. If the block is not given, an exception will be raised (unless dirty
is set to true
). The lifetime must be in seconds. The default lifetime is huge, which means that the key will never be expired.
If the dirty
argument is set to true
, a previously calculated result will be returned if it exists and is already expired.
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# File 'lib/zache.rb', line 100 def get(key, lifetime: 2**32, dirty: false, &block) if block_given? return @hash[key][:value] if (dirty || @dirty) && locked? && expired?(key) && @hash.key?(key) synchronized { calc(key, lifetime, &block) } else rec = @hash[key] if expired?(key) return rec[:value] if dirty || @dirty @hash.delete(key) rec = nil end raise 'The key is absent in the cache' if rec.nil? rec[:value] end end |
#locked? ⇒ Boolean
Is cache currently locked doing something?
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# File 'lib/zache.rb', line 143 def locked? @mutex.locked? end |
#mtime(key) ⇒ Object
Returns the modification time of the key, if it exists. If not, current time is returned.
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# File 'lib/zache.rb', line 137 def mtime(key) rec = @hash[key] rec.nil? ? Time.now : rec[:start] end |
#put(key, value, lifetime: 2**32) ⇒ Object
Put a value into the cache.
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# File 'lib/zache.rb', line 148 def put(key, value, lifetime: 2**32) synchronized do @hash[key] = { value: value, start: Time.now, lifetime: lifetime } end end |
#remove(key) ⇒ Object
Removes the value from the hash, by the provied key. If the key is absent and the block is provided, the block will be called.
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# File 'lib/zache.rb', line 160 def remove(key) synchronized { @hash.delete(key) { yield if block_given? } } end |
#remove_all ⇒ Object
Remove all keys from the cache.
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# File 'lib/zache.rb', line 165 def remove_all synchronized { @hash = {} } end |
#remove_by ⇒ Object
Remove all keys that match the block.
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# File 'lib/zache.rb', line 170 def remove_by synchronized do @hash.each_key do |k| @hash.delete(k) if yield(k) end end end |
#size ⇒ Object
Total number of keys currently in cache.
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# File 'lib/zache.rb', line 85 def size @hash.size end |