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require_relative '../../spec_helper'
require 'thread'
describe "ConditionVariable#broadcast" do
it "releases all threads waiting in line for this resource" do
m = Mutex.new
cv = ConditionVariable.new
threads = []
r1 = []
r2 = []
# large number to attempt to cause race conditions
100.times do |i|
threads << Thread.new(i) do |tid|
m.synchronize do
r1 << tid
cv.wait(m)
r2 << tid
end
end
end
# wait for all threads to acquire the mutex the first time
Thread.pass until m.synchronize { r1.size == threads.size }
# wait until all threads are sleeping (ie waiting)
Thread.pass until threads.all?(&:stop?)
r2.should be_empty
m.synchronize do
cv.broadcast
end
threads.each {|t| t.join }
# ensure that all threads that enter cv.wait are released
r2.sort.should == r1.sort
# note that order is not specified as broadcast results in a race
# condition on regaining the lock m
end
end
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