Created
March 13, 2026 17:57
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An example of double-checked locking with a Mutex for safe concurrent access
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| module Example | |
| ONCE = Once.new | |
| def self.once | |
| ONCE.call do | |
| # work | |
| end | |
| end | |
| end |
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| class Once | |
| def initialize | |
| @mutex = Mutex.new | |
| @done = false | |
| end | |
| def done? = @done | |
| def call | |
| return if @done | |
| @mutex.synchronize do | |
| return if @done | |
| yield | |
| @done = true | |
| end | |
| end | |
| end |
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