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Add popping and selection with a matcher and peek to channel

This commit is contained in:
Petr Chalupa 2019-01-29 14:01:05 +01:00
parent 16bc2beff1
commit bf74c67ba5
2 changed files with 254 additions and 114 deletions
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309
lib-edge/concurrent/edge/channel.rb
View File

@ -16,8 +16,6 @@ module Concurrent
# TODO (pitr-ch 14-Jan-2019): better documentation, do few examples from go
# TODO (pitr-ch 12-Dec-2018): implement channel closing,
# - as a child class? To also have a channel which cannot be closed.
# TODO (pitr-ch 18-Dec-2018): It needs unpop to return non matched messages read by actor or rather atomic operations pop_first_matching
# TODO (pitr-ch 15-Jan-2019): needs peek
# TODO (pitr-ch 26-Dec-2016): replace with lock-free implementation, at least getting a message when available should be lock free same goes for push with space available
# @!macro channel.warn.blocks
@ -43,12 +41,23 @@ module Concurrent
end
end
NOTHING = Object.new
private_constant :NOTHING
# An object which matches anything (with #===)
ANY = Object.new.tap do |any|
def any.===(other)
true
end
end
# Create channel.
# @param [Integer, UNLIMITED_CAPACITY] capacity the maximum number of messages which can be stored in the channel.
def initialize(capacity = UNLIMITED_CAPACITY)
super()
@Capacity = capacity
@Mutex = Mutex.new
@Capacity = capacity
@Mutex = Mutex.new
# TODO (pitr-ch 28-Jan-2019): consider linked lists or other data structures for following attributes, things are being deleted from the middle
@Probes = []
@Messages = []
@PendingPush = []
@ -114,90 +123,158 @@ module Concurrent
result == pushed_op ? self : result
end
# Pop a message from the channel if there is one available.
# @param [Object] no_value returned when there is no message available
# @return [Object, no_value] message or nil when there is no message
# @!macro promises.channel.try_pop
# Pop a message from the channel if there is one available.
# @param [Object] no_value returned when there is no message available
# @return [Object, no_value] message or nil when there is no message
def try_pop(no_value = nil)
message = try_pop_disambiguated
message == NOTHING ? no_value : message
try_pop_matching ANY, no_value
end
# Returns a future witch will become fulfilled with a value from the channel when one is available.
# @!macro chanel.operation_wait
# @!macro promises.channel.try_pop
# @!macro promises.channel.param.matcher
# @param [#===] matcher only consider message which matches `matcher === a_message`
def try_pop_matching(matcher, no_value = nil)
@Mutex.synchronize do
message = ns_shift_message matcher
return message if message != NOTHING
message = ns_consume_pending_push matcher
return message != NOTHING ? message : no_value
end
end
# @!macro promises.channel.pop_op
# Returns a future witch will become fulfilled with a value from the channel when one is available.
# @!macro chanel.operation_wait
#
# @param [ResolvableFuture] probe the future which will be fulfilled with a channel value
# @return [Future(Object)] the probe, its value will be the message when available.
# @param [ResolvableFuture] probe the future which will be fulfilled with a channel value
# @return [Future(Object)] the probe, its value will be the message when available.
def pop_op(probe = Promises.resolvable_future)
@Mutex.synchronize { ns_pop_op(probe, false) }
@Mutex.synchronize { ns_pop_op(ANY, probe, false) }
end
# Blocks current thread until a message is available in the channel for popping.
# @!macro promises.channel.pop_op
# @!macro promises.channel.param.matcher
def pop_op_matching(matcher, probe = Promises.resolvable_future)
@Mutex.synchronize { ns_pop_op(matcher, probe, false) }
end
# @!macro promises.channel.pop
# Blocks current thread until a message is available in the channel for popping.
#
# @!macro channel.warn.blocks
# @!macro channel.param.timeout
# @!macro promises.param.timeout_value
# @return [Object, nil] message or nil when timed out
# @!macro channel.warn.blocks
# @!macro channel.param.timeout
# @!macro promises.param.timeout_value
# @return [Object, nil] message or nil when timed out
def pop(timeout = nil, timeout_value = nil)
pop_matching ANY, timeout, timeout_value
end
# @!macro promises.channel.pop
# @!macro promises.channel.param.matcher
def pop_matching(matcher, timeout = nil, timeout_value = nil)
# TODO (pitr-ch 27-Jan-2019): should it try to match pending pushes if it fails to match in the buffer? Maybe only if the size is zero. It could be surprising if it's used as a throttle it might be expected that it will not pop if buffer is full of messages which di not match, it might it expected it will block until the message is added to the buffer
# that it returns even if the buffer is full. User might expect that it has to be in the buffer first.
probe = @Mutex.synchronize do
message = ns_shift_message
message = ns_shift_message matcher
if message == NOTHING
message = ns_consume_pending_push
message = ns_consume_pending_push matcher
return message if message != NOTHING
else
new_message = ns_consume_pending_push
new_message = ns_consume_pending_push ANY
@Messages.push new_message unless new_message == NOTHING
return message
end
probe = Promises.resolvable_future
@Probes.push false, probe
@Probes.push probe, false, matcher
probe
end
probe.value!(timeout, timeout_value, [true, timeout_value, nil])
end
# If message is available in the receiver or any of the provided channels
# the channel message pair is returned. If there is no message nil is returned.
# The returned channel is the origin of the message.
# @!macro promises.channel.peek
# Behaves as {#try_pop} but it does not remove the message from the channel
# @param [Object] no_value returned when there is no message available
# @return [Object, no_value] message or nil when there is no message
def peek(no_value = nil)
peek_matching ANY, no_value
end
# @!macro promises.channel.peek
# @!macro promises.channel.param.matcher
def peek_matching(matcher, no_value = nil)
@Mutex.synchronize do
message = ns_shift_message matcher, false
return message if message != NOTHING
message = ns_consume_pending_push matcher, false
return message != NOTHING ? message : no_value
end
end
# @!macro promises.channel.try_select
# If message is available in the receiver or any of the provided channels
# the channel message pair is returned. If there is no message nil is returned.
# The returned channel is the origin of the message.
#
# @param [Channel, ::Array<Channel>] channels
# @return [::Array(Channel, Object), nil]
# pair [channel, message] if one of the channels is available for reading
# @param [Channel, ::Array<Channel>] channels
# @return [::Array(Channel, Object), nil]
# pair [channel, message] if one of the channels is available for reading
def try_select(channels)
try_select_matching ANY, channels
end
# @!macro promises.channel.try_select
# @!macro promises.channel.param.matcher
def try_select_matching(matcher, channels)
message = nil
channel = [self, *channels].find do |ch|
message = ch.try_pop_disambiguated
message = ch.try_pop_matching(matcher, NOTHING)
message != NOTHING
end
channel ? [channel, message] : nil
end
# When message is available in the receiver or any of the provided channels
# the future is fulfilled with a channel message pair.
# The returned channel is the origin of the message.
# @!macro chanel.operation_wait
# @!macro promises.channel.select_op
# When message is available in the receiver or any of the provided channels
# the future is fulfilled with a channel message pair.
# The returned channel is the origin of the message.
# @!macro chanel.operation_wait
#
# @param [Channel, ::Array<Channel>] channels
# @param [ResolvableFuture] probe the future which will be fulfilled with the message
# @return [ResolvableFuture(::Array(Channel, Object))] a future which is fulfilled with
# pair [channel, message] when one of the channels is available for reading
# @param [Channel, ::Array<Channel>] channels
# @param [ResolvableFuture] probe the future which will be fulfilled with the message
# @return [ResolvableFuture(::Array(Channel, Object))] a future which is fulfilled with
# pair [channel, message] when one of the channels is available for reading
def select_op(channels, probe = Promises.resolvable_future)
[self, *channels].each { |ch| ch.partial_select_op probe }
select_op_matching ANY, channels, probe
end
# @!macro promises.channel.select_op
# @!macro promises.channel.param.matcher
def select_op_matching(matcher, channels, probe = Promises.resolvable_future)
[self, *channels].each { |ch| ch.partial_select_op matcher, probe }
probe
end
# As {#select_op} but does not return future,
# it block current thread instead until there is a message available
# in the receiver or in any of the channels.
# @!macro promises.channel.select
# As {#select_op} but does not return future,
# it block current thread instead until there is a message available
# in the receiver or in any of the channels.
#
# @!macro channel.warn.blocks
# @param [Channel, ::Array<Channel>] channels
# @!macro channel.param.timeout
# @return [::Array(Channel, Object), nil] message or nil when timed out
# @see #select_op
# @!macro channel.warn.blocks
# @param [Channel, ::Array<Channel>] channels
# @!macro channel.param.timeout
# @return [::Array(Channel, Object), nil] message or nil when timed out
# @see #select_op
def select(channels, timeout = nil)
probe = select_op(channels)
select_matching ANY, channels, timeout
end
# @!macro promises.channel.select
# @!macro promises.channel.param.matcher
def select_matching(matcher, channels, timeout = nil)
probe = select_op_matching(matcher, channels)
probe.value!(timeout, nil, [true, nil, nil])
end
@ -233,37 +310,44 @@ module Concurrent
end
# @see #select
# @return [Object, nil]
# @return [::Array(Channel, Object), nil]
def select(channels, timeout = nil)
channels.first.select(channels[1..-1], timeout)
end
# @see #try_select_matching
# @return [::Array(Channel, Object)]
def try_select_matching(matcher, channels)
channels.first.try_select_matching(matcher, channels[1..-1])
end
# @see #select_op_matching
# @return [Future(::Array(Channel, Object))]
def select_op_matching(matcher, channels, probe = Promises.resolvable_future)
channels.first.select_op_matching(matcher, channels[1..-1], probe)
end
# @see #select_matching
# @return [::Array(Channel, Object), nil]
def select_matching(matcher, channels, timeout = nil)
channels.first.select_matching(matcher, channels[1..-1], timeout)
end
end
# @!visibility private
def partial_select_op(probe)
@Mutex.synchronize { ns_pop_op(probe, true) }
end
protected
def try_pop_disambiguated
@Mutex.synchronize do
message = ns_shift_message
return message if message != NOTHING
return ns_consume_pending_push
end
def partial_select_op(matcher, probe)
@Mutex.synchronize { ns_pop_op(matcher, probe, true) }
end
private
def ns_pop_op(probe, include_channel)
message = ns_shift_message
def ns_pop_op(matcher, probe, include_channel)
message = ns_shift_message matcher
# got message from buffer
if message != NOTHING
if probe.fulfill(include_channel ? [self, message] : message, false)
new_message = ns_consume_pending_push
new_message = ns_consume_pending_push ANY
@Messages.push new_message unless new_message == NOTHING
else
@Messages.unshift message
@ -272,69 +356,66 @@ module Concurrent
end
# no message in buffer, try to pair with a pending push
i = 0
while true
message, pushed = @PendingPush.first 2
message, pushed = @PendingPush[i, 2]
break if pushed.nil?
value = include_channel ? [self, message] : message
if Promises::Resolvable.atomic_resolution(probe => [true, value, nil], pushed => [true, self, nil])
@PendingPush.shift 2
return probe
if matcher === message
value = include_channel ? [self, message] : message
if Promises::Resolvable.atomic_resolution(probe => [true, value, nil],
pushed => [true, self, nil])
@PendingPush[i, 2] = []
return probe
end
if probe.resolved?
return probe
end
# so pushed.resolved? has to be true, remove the push
@PendingPush[i, 2] = []
end
if pushed.resolved?
@PendingPush.shift 2
next
end
if probe.resolved?
return probe
end
raise 'should not reach'
i += 2
end
# no push to pair with
# TODO (pitr-ch 11-Jan-2019): clear up probes when timed out, use callback
@Probes.push include_channel, probe if probe.pending?
@Probes.push probe, include_channel, matcher if probe.pending?
return probe
end
def ns_consume_pending_push
return NOTHING if @PendingPush.empty?
def ns_consume_pending_push(matcher, remove = true)
i = 0
while true
message, pushed = @PendingPush.shift 2
message, pushed = @PendingPush[i, 2]
return NOTHING unless pushed
# can fail if timed-out, so try without error
if pushed.fulfill(self, false)
# pushed fulfilled so actually push the message
return message
end
end
end
def ns_peek_pending_push
return NOTHING if @PendingPush.empty?
while true
message, pushed = @PendingPush.first 2
return NOTHING unless pushed
# can be timed-out
if pushed.resolved?
@PendingPush.shift 2
# and repeat
else
return message
if matcher === message
resolved = pushed.resolved?
@PendingPush[i, 2] = [] if remove || resolved
# can fail if timed-out, so try without error
if remove ? pushed.fulfill(self, false) : !resolved
# pushed fulfilled so actually push the message
return message
end
end
i += 2
end
end
def ns_try_push(message)
i = 0
while true
include_channel, probe = @Probes.shift(2)
probe, include_channel, matcher = @Probes[i, 3]
break unless probe
if probe.fulfill(include_channel ? [self, message] : message, false)
if matcher === message && probe.fulfill(include_channel ? [self, message] : message, false)
@Probes[i, 3] = []
return true
end
i += 3
end
if @Capacity > @Messages.size
@ -345,18 +426,18 @@ module Concurrent
end
end
NOTHING = Object.new
private_constant :NOTHING
def ns_shift_message(matcher, remove = true)
i = 0
while true
message = @Messages.fetch(i, NOTHING)
return NOTHING if message == NOTHING
def ns_shift_message
@Messages.empty? ? NOTHING : @Messages.shift
end
if matcher === message
@Messages.delete_at i if remove
return message
end
def ns_try_peek
if @Messages.empty?
ns_peek_pending_push
else
@Messages.shift
i += 1
end
end
end

59
spec/concurrent/edge/channel_spec.rb
View File

@ -118,6 +118,65 @@ RSpec.describe 'Concurrent' do
expect(pop_op.value!).to eq :v2
end
specify "#(try_)pop(_op)_matching" do
channel = Concurrent::Promises::Channel.new 2
channel.push 'junk'
channel.push :v1
expect(channel.size).to eq 2
expect(channel.try_pop_matching(Symbol)).to eq :v1
expect(channel.size).to eq 1
expect(channel.try_pop_matching(Symbol)).to eq nil
expect(channel.size).to eq 1
channel = Concurrent::Promises::Channel.new 2
channel.push 'junk'
channel.push :v1
expect(channel.pop_matching(Symbol)).to eq :v1
expect(channel.size).to eq 1
thread = in_thread { channel.pop_matching(Symbol) }
is_sleeping thread
expect(channel.size).to eq 1
channel.push 'junk'
channel.pop
channel.push :v2
expect(thread.value).to eq :v2
expect(channel.size).to eq 1
channel = Concurrent::Promises::Channel.new 2
channel.push 'junk'
channel.push :v1
expect(channel.pop_matching(Symbol)).to eq :v1
expect(channel.size).to eq 1
thread = in_thread { channel.pop_matching(Symbol, 0.01) }
is_sleeping thread
expect(channel.size).to eq 1
expect(thread.value).to eq nil
channel.push :v2
expect(channel.size).to eq 2
expect(channel.pop_matching(Symbol)).to eq :v2
expect(channel.size).to eq 1
thread = in_thread { channel.pop_matching(Symbol,1) }
is_sleeping thread
channel.push :v3
expect(channel.size).to eq 1
expect(thread.value).to eq :v3
channel.push :v4
expect(channel.pop_matching(Symbol,0)).to eq :v4
channel = Concurrent::Promises::Channel.new 2
channel.push 'junk'
channel.push :v1
expect(channel.pop_op_matching(Symbol).value!).to eq :v1
expect(channel.size).to eq 1
pop_op = channel.pop_op_matching(Symbol)
expect(channel.size).to eq 1
expect(pop_op.pending?).to be_truthy
channel.push :v2
expect(channel.size).to eq 1
expect(pop_op.value!).to eq :v2
end
specify "#(try_)select(_op)" do
channel1 = Concurrent::Promises::Channel.new 1
channel2 = Concurrent::Promises::Channel.new 1