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-- Exercise the Queue, WaitQueue, ErrorQueue family
Queue = require('Queue')
WaitQueue = require('WaitQueue')
ErrorQueue = require('ErrorQueue')
util = require('util')
inspect = require('inspect')
-- resume() wrapper to propagate errors
function resume(co, ...)
-- if there's an idiom other than table.pack() to assign an arbitrary
-- number of return values, I don't yet know it
local ok_result = table.pack(coroutine.resume(co, ...))
if not ok_result[1] then
-- if [1] is false, then [2] is the error message
error(ok_result[2])
end
-- ok is true, whew, just return the rest of the values
return table.unpack(ok_result, 2)
end
-- ------------------ Queue variables are instance-specific ------------------
q1 = Queue:new()
q2 = Queue:new()
q1:Enqueue(17)
assert(not q1:IsEmpty())
assert(q2:IsEmpty())
assert(q1:Dequeue() == 17)
assert(q1:Dequeue() == nil)
assert(q2:Dequeue() == nil)
-- ----------------------------- test WaitQueue ------------------------------
q1 = WaitQueue:new()
q2 = WaitQueue:new()
result = {}
values = { 1, 1, 2, 3, 5, 8, 13, 21 }
for i, value in pairs(values) do
q1:Enqueue(value)
end
-- close() while not empty tests that queue drains before reporting done
q1:close()
-- ensure that WaitQueue instance variables are in fact independent
assert(q2:IsEmpty())
-- consumer() coroutine to pull from the passed q until closed
function consumer(desc, q)
print(string.format('consumer(%s) start', desc))
local value = q:Dequeue()
while value ~= nil do
print(string.format('consumer(%s) got %q', desc, value))
table.insert(result, value)
value = q:Dequeue()
end
print(string.format('consumer(%s) done', desc))
end
-- run two consumers
coa = coroutine.create(consumer)
cob = coroutine.create(consumer)
-- Since consumer() doesn't yield while it can still retrieve values,
-- consumer(a) will dequeue all values from q1 and return when done.
resume(coa, 'a', q1)
-- consumer(b) will wake up to find the queue empty and closed.
resume(cob, 'b', q1)
coroutine.close(coa)
coroutine.close(cob)
print('values:', inspect(values))
print('result:', inspect(result))
assert(util.equal(values, result))
-- try incrementally enqueueing values
q3 = WaitQueue:new()
result = {}
values = { 'This', 'is', 'a', 'test', 'script' }
coros = {}
for _, name in {'a', 'b'} do
local coro = coroutine.create(consumer)
table.insert(coros, coro)
-- Resuming both coroutines should leave them both waiting for a queue item.
resume(coro, name, q3)
end
for _, s in pairs(values) do
print(string.format('Enqueue(%q)', s))
q3:Enqueue(s)
end
q3:close()
function joinall(coros)
local running
local errors = 0
repeat
running = false
for i, coro in pairs(coros) do
if coroutine.status(coro) == 'suspended' then
running = true
-- directly call coroutine.resume() instead of our resume()
-- wrapper because we explicitly check for errors here
local ok, message = coroutine.resume(coro)
if not ok then
print('*** ' .. message)
errors += 1
end
if coroutine.status(coro) == 'dead' then
coros[i] = nil
end
end
end
until not running
return errors
end
joinall(coros)
print(string.format('%q', table.concat(result, ' ')))
assert(util.equal(values, result))
-- ----------------------------- test ErrorQueue -----------------------------
q4 = ErrorQueue:new()
result = {}
values = { 'This', 'is', 'a', 'test', 'script' }
coros = {}
for _, name in {'a', 'b'} do
local coro = coroutine.create(consumer)
table.insert(coros, coro)
-- Resuming both coroutines should leave them both waiting for a queue item.
resume(coro, name, q4)
end
for i = 1, 4 do
print(string.format('Enqueue(%q)', values[i]))
q4:Enqueue(values[i])
end
q4:Error('something went wrong')
assert(joinall(coros) == 2)
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