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|
# frozen_string_literal: true
module Mongo
module DriverBench
module Parallel
# An implementation of a counter variable that can be waited on, which
# will signal when the variable reaches zero.
#
# @api private
class Counter
# Create a new Counter object with the given initial value.
#
# @param [ Integer ] value the starting value of the counter (defaults
# to zero).
def initialize(value = 0)
@mutex = Thread::Mutex.new
@condition = Thread::ConditionVariable.new
@counter = value
end
# Describes a block where the counter is incremented before executing
# it, and decremented afterward.
#
# @yield Calls the provided block with no arguments.
def enter
inc
yield
ensure
dec
end
# Waits for the counter to be zero.
def wait
@mutex.synchronize do
return if @counter.zero?
@condition.wait(@mutex)
end
end
# Increments the counter.
def inc
@mutex.synchronize { @counter += 1 }
end
# Decrements the counter. If the counter reaches zero,
# a signal is sent to any waiting process.
def dec
@mutex.synchronize do
@counter -= 1 if @counter.positive?
@condition.signal if @counter.zero?
end
end
end
end
end
end
|
