63 lines
2.5 KiB
Ruby
63 lines
2.5 KiB
Ruby
# frozen_string_literal: true
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module Gitlab
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# This module provides helper methods which are integrated with GitLab::ExclusiveLease
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module ExclusiveLeaseHelpers
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FailedToObtainLockError = Class.new(StandardError)
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##
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# This helper method blocks a process/thread until the lease can be acquired, either due to
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# the lease TTL expiring, or due to the current holder explicitly releasing
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# their hold.
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#
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# If the lease cannot be obtained, raises `FailedToObtainLockError`.
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#
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# @param [String] key The lock the thread will try to acquire. Only one thread
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# in one process across all Rails instances can hold this named lock at any
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# one time.
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# @param [Float] ttl: The length of time the lock will be valid for. The lock
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# will be automatically be released after this time, so any work should be
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# completed within this time.
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# @param [Integer] retries: The maximum number of times we will re-attempt
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# to acquire the lock. The maximum number of attempts will be `retries + 1`:
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# one for the initial attempt, and then one for every re-try.
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# @param [Float|Proc] sleep_sec: Either a number of seconds to sleep, or
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# a proc that computes the sleep time given the number of preceding attempts
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# (from 1 to retries - 1)
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#
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# Note: It's basically discouraged to use this method in a webserver thread,
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# because this ties up all thread related resources until all `retries` are consumed.
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# This could potentially eat up all connection pools.
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def in_lock(key, ttl: 1.minute, retries: 10, sleep_sec: 0.01.seconds)
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raise ArgumentError, 'Key needs to be specified' unless key
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Gitlab::Instrumentation::ExclusiveLock.increment_requested_count
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lease = SleepingLock.new(key, timeout: ttl, delay: sleep_sec)
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with_instrumentation(:wait) do
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lease.obtain(1 + retries)
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end
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with_instrumentation(:hold) do
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yield(lease.retried?, lease)
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end
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ensure
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lease&.cancel
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end
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private
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def with_instrumentation(metric)
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start_time = Time.current
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yield
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ensure
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if metric == :wait
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Gitlab::Instrumentation::ExclusiveLock.add_wait_duration(Time.current - start_time)
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else
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Gitlab::Instrumentation::ExclusiveLock.add_hold_duration(Time.current - start_time)
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end
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end
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end
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end
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