ruby 41 lines · 5 steps

A thread-safe debouncer in Ruby

Collect rapid calls into one batch and flush them after a quiet period, using a mutex and a resettable timer thread.

Explained by highlit

Advanced concurrency debouncing mutex threads batching

1class Debouncer
def initialize(delay:)
  @delay = delay
  @mutex = Mutex.new
  @pending = []
  @timer = nil
end
8 
def call(item, &flush)
  @mutex.synchronize do
    @pending << item
    @flush = flush
    schedule
  end
end
16 
private
18 
def schedule
  @timer&.kill
  @timer = Thread.new do
    sleep @delay
    flush_now
  end
end
26 
def flush_now
  batch = nil
  handler = nil
  @mutex.synchronize do
    return if @pending.empty?
    batch = @pending
    handler = @flush
    @pending = []
    @timer = nil
  end
  handler.call(batch)
rescue => e
  warn "[Debouncer] flush failed: #{e.message}"
end
41end

01 / 01

STEP 01

Walkthrough

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Three takeaways

1Debouncing coalesces bursts of events into a single delayed action by resetting a timer on every new call.
2A mutex guards shared state so concurrent callers and the timer thread never see a half-updated batch.
3Draining state under the lock and running the handler outside it keeps the critical section short and avoids holding the lock during slow work.

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