Class: Concurrent::Promises::Future

Inherits:
AbstractEventFuture show all
Includes:
ActorIntegration, FlatShortcuts, NewChannelIntegration
Defined in:
lib/concurrent/promises.rb,
lib-edge/concurrent/edge/promises.rb,
lib-edge/concurrent/edge/promises.rb,
lib-edge/concurrent/edge/old_channel_integration.rb

Overview

Represents a value which will become available in future. May reject with a reason instead, e.g. when the tasks raises an exception.

Direct Known Subclasses

ResolvableFuture

Defined Under Namespace

Modules: ActorIntegration, FlatShortcuts, NewChannelIntegration

Instance Method Summary collapse

Instance Method Details

#any(event_or_future) ⇒ Future Also known as: |

Creates a new event which will be resolved when the first of receiver, event_or_future resolves. Returning future will have value nil if event_or_future is event and resolves first.

Returns:



1074
1075
1076
 
# File 'lib/concurrent/promises.rb', line 1074

def any(event_or_future)
  AnyResolvedFuturePromise.new_blocked_by2(self, event_or_future, @DefaultExecutor).future
end

#delay ⇒ Future

Creates new future dependent on receiver which will not evaluate until touched, see AbstractEventFuture#touch. In other words, it inserts delay into the chain of Futures making rest of it lazy evaluated.

Returns:



1084
1085
1086
1087
 
# File 'lib/concurrent/promises.rb', line 1084

def delay
  event = DelayPromise.new(@DefaultExecutor).event
  ZipFutureEventPromise.new_blocked_by2(self, event, @DefaultExecutor).future
end

#exception(*args) ⇒ Exception

Allows rejected Future to be risen with raise method. If the reason is not an exception Runtime.new(reason) is returned.

Examples:

raise Promises.rejected_future(StandardError.new("boom"))
raise Promises.rejected_future("or just boom")

Returns:

  • (Exception)

Raises:



1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
 
# File 'lib/concurrent/promises.rb', line 1002

def exception(*args)
  raise Concurrent::Error, 'it is not rejected' unless rejected?
  raise ArgumentError unless args.size <= 1
  reason = Array(internal_state.reason).flatten.compact
  if reason.size > 1
    ex = Concurrent::MultipleErrors.new reason
    ex.set_backtrace(caller)
    ex
  else
    ex = if reason[0].respond_to? :exception
           reason[0].exception(*args)
         else
           RuntimeError.new(reason[0]).exception(*args)
         end
    ex.set_backtrace Array(ex.backtrace) + caller
    ex
  end
end

#flat_event ⇒ Event

Creates new event which will be resolved when the returned event by receiver is. Be careful if the receiver rejects it will just resolve since Event does not hold reason.

Returns:



1119
1120
1121
 
# File 'lib/concurrent/promises.rb', line 1119

def flat_event
  FlatEventPromise.new_blocked_by1(self, @DefaultExecutor).event
end

#flat_future(level = 1) ⇒ Future Also known as: flat

Creates new future which will have result of the future returned by receiver. If receiver rejects it will have its rejection.

Parameters:

  • level (Integer) (defaults to: 1) —

    how many levels of futures should flatten

Returns:



1109
1110
1111
 
# File 'lib/concurrent/promises.rb', line 1109

def flat_future(level = 1)
  FlatFuturePromise.new_blocked_by1(self, level, @DefaultExecutor).future
end

#fulfilled? ⇒ Boolean

Is it in fulfilled state?

Returns:

  • (Boolean) 


910
911
912
913
 
# File 'lib/concurrent/promises.rb', line 910

def fulfilled?
  state = internal_state
  state.resolved? && state.fulfilled?
end

#on_fulfillment(*args, &callback) ⇒ self

Shortcut of #on_fulfillment_using with default :io executor supplied.

Returns:

  • (self)

See Also:



1125
1126
1127
 
# File 'lib/concurrent/promises.rb', line 1125

def on_fulfillment(*args, &callback)
  on_fulfillment_using @DefaultExecutor, *args, &callback
end

#on_fulfillment!(*args) {|value, *args| ... } ⇒ self

Stores the callback to be executed synchronously on resolving thread after it is fulfilled. Does nothing on rejection.

Parameters:

  • args (Object) —

    arguments which are passed to the task when it's executed. (It might be prepended with other arguments, see the @yeild section).

Yields:

  • (value, *args) —

    to the callback.

Yield Returns:

  • is forgotten.

Returns:

  • (self) 


1136
1137
1138
 
# File 'lib/concurrent/promises.rb', line 1136

def on_fulfillment!(*args, &callback)
  add_callback :callback_on_fulfillment, args, callback
end

#on_fulfillment_using(executor, *args) {|value, *args| ... } ⇒ self

Stores the callback to be executed asynchronously on executor after it is fulfilled. Does nothing on rejection.

Parameters:

  • executor (Executor, :io, :fast) —

    Instance of an executor or a name of the global executor. The task is executed on it, default executor remains unchanged.

  • args (Object) —

    arguments which are passed to the task when it's executed. (It might be prepended with other arguments, see the @yeild section).

Yields:

  • (value, *args) —

    to the callback.

Yield Returns:

  • is forgotten.

Returns:

  • (self) 


1148
1149
1150
 
# File 'lib/concurrent/promises.rb', line 1148

def on_fulfillment_using(executor, *args, &callback)
  add_callback :async_callback_on_fulfillment, executor, args, callback
end

#on_rejection(*args, &callback) ⇒ self

Shortcut of #on_rejection_using with default :io executor supplied.

Returns:

  • (self)

See Also:



1154
1155
1156
 
# File 'lib/concurrent/promises.rb', line 1154

def on_rejection(*args, &callback)
  on_rejection_using @DefaultExecutor, *args, &callback
end

#on_rejection!(*args) {|reason, *args| ... } ⇒ self

Stores the callback to be executed synchronously on resolving thread after it is rejected. Does nothing on fulfillment.

Parameters:

  • args (Object) —

    arguments which are passed to the task when it's executed. (It might be prepended with other arguments, see the @yeild section).

Yields:

  • (reason, *args) —

    to the callback.

Yield Returns:

  • is forgotten.

Returns:

  • (self) 


1165
1166
1167
 
# File 'lib/concurrent/promises.rb', line 1165

def on_rejection!(*args, &callback)
  add_callback :callback_on_rejection, args, callback
end

#on_rejection_using(executor, *args) {|reason, *args| ... } ⇒ self

Stores the callback to be executed asynchronously on executor after it is rejected. Does nothing on fulfillment.

Parameters:

  • executor (Executor, :io, :fast) —

    Instance of an executor or a name of the global executor. The task is executed on it, default executor remains unchanged.

  • args (Object) —

    arguments which are passed to the task when it's executed. (It might be prepended with other arguments, see the @yeild section).

Yields:

  • (reason, *args) —

    to the callback.

Yield Returns:

  • is forgotten.

Returns:

  • (self) 


1177
1178
1179
 
# File 'lib/concurrent/promises.rb', line 1177

def on_rejection_using(executor, *args, &callback)
  add_callback :async_callback_on_rejection, executor, args, callback
end

#reason(timeout = nil, timeout_value = nil) ⇒ Object, timeout_value

Note:

This function potentially blocks current thread until the Future is resolved. Be careful it can deadlock. Try to chain instead.

Note:

Make sure returned nil is not confused with timeout, no value when rejected, no reason when fulfilled, etc. Use more exact methods if needed, like AbstractEventFuture#wait, #value!, #result, etc.

Returns reason of future's rejection. Calls AbstractEventFuture#touch.

Parameters:

  • timeout (Numeric) (defaults to: nil) —

    the maximum time in second to wait.

  • timeout_value (Object) (defaults to: nil) —

    a value returned by the method when it times out

Returns:

  • (Object, timeout_value) —

    the reason, or timeout_value on timeout, or nil on fulfillment.



955
956
957
958
959
960
961
 
# File 'lib/concurrent/promises.rb', line 955

def reason(timeout = nil, timeout_value = nil)
  if wait_until_resolved timeout
    internal_state.reason
  else
    timeout_value
  end
end

#rejected? ⇒ Boolean

Is it in rejected state?

Returns:

  • (Boolean) 


917
918
919
920
 
# File 'lib/concurrent/promises.rb', line 917

def rejected?
  state = internal_state
  state.resolved? && !state.fulfilled?
end

#rescue(*args, &task) ⇒ Future

Shortcut of #rescue_on with default :io executor supplied.

Returns:

See Also:



1041
1042
1043
 
# File 'lib/concurrent/promises.rb', line 1041

def rescue(*args, &task)
  rescue_on @DefaultExecutor, *args, &task
end

#rescue_on(executor, *args) {|reason, *args| ... } ⇒ Future

Chains the task to be executed asynchronously on executor after it rejects. Does not run the task if it fulfills. It will resolve though, triggering any dependent futures.

Parameters:

  • executor (Executor, :io, :fast) —

    Instance of an executor or a name of the global executor. The task is executed on it, default executor remains unchanged.

  • args (Object) —

    arguments which are passed to the task when it's executed. (It might be prepended with other arguments, see the @yeild section).

Yields:

  • (reason, *args) —

    to the task.

Yield Returns:

  • will become result of the returned Future. Its returned value becomes #value fulfilling it, raised exception becomes #reason rejecting it.

Returns:



1053
1054
1055
 
# File 'lib/concurrent/promises.rb', line 1053

def rescue_on(executor, *args, &task)
  RescuePromise.new_blocked_by1(self, @DefaultExecutor, executor, args, &task).future
end

#result(timeout = nil) ⇒ Array(Boolean, Object, Object), nil

Note:

This function potentially blocks current thread until the Future is resolved. Be careful it can deadlock. Try to chain instead.

Returns triplet fulfilled?, value, reason. Calls AbstractEventFuture#touch.

Parameters:

  • timeout (Numeric) (defaults to: nil) —

    the maximum time in second to wait.

Returns:

  • (Array(Boolean, Object, Object), nil) —

    triplet of fulfilled?, value, reason, or nil on timeout.



970
971
972
 
# File 'lib/concurrent/promises.rb', line 970

def result(timeout = nil)
  internal_state.result if wait_until_resolved timeout
end

#run(run_test = method(:run_test)) ⇒ Future

Allows to use futures as green threads. The receiver has to evaluate to a future which represents what should be done next. It basically flattens indefinitely until non Future values is returned which becomes result of the returned future. Any encountered exception will become reason of the returned future.

Examples:

body = lambda do |v|
  v += 1
  v < 5 ? Promises.future(v, &body) : v
end
Promises.future(0, &body).run.value! # => 5

Parameters:

  • run_test (#call(value)) (defaults to: method(:run_test)) —

    an object which when called returns either Future to keep running with or nil, then the run completes with the value. The run_test can be used to extract the Future from deeper structure, or to distinguish Future which is a resulting value from a future which is suppose to continue running.

Returns:



1199
1200
1201
 
# File 'lib/concurrent/promises.rb', line 1199

def run(run_test = method(:run_test))
  RunFuturePromise.new_blocked_by1(self, @DefaultExecutor, run_test).future
end

#schedule(intended_time) ⇒ Future

Creates new event dependent on receiver scheduled to execute on/in intended_time. In time is interpreted from the moment the receiver is resolved, therefore it inserts delay into the chain.

Parameters:

  • intended_time (Numeric, Time) —

    Numeric means to run in intended_time seconds. Time means to run on intended_time.

Returns:



1091
1092
1093
1094
1095
1096
 
# File 'lib/concurrent/promises.rb', line 1091

def schedule(intended_time)
  chain do
    event = ScheduledPromise.new(@DefaultExecutor, intended_time).event
    ZipFutureEventPromise.new_blocked_by2(self, event, @DefaultExecutor).future
  end.flat
end

#then(*args, &task) ⇒ Future

Shortcut of #then_on with default :io executor supplied.

Returns:

See Also:



1023
1024
1025
 
# File 'lib/concurrent/promises.rb', line 1023

def then(*args, &task)
  then_on @DefaultExecutor, *args, &task
end

#then_on(executor, *args) {|value, *args| ... } ⇒ Future

Chains the task to be executed asynchronously on executor after it fulfills. Does not run the task if it rejects. It will resolve though, triggering any dependent futures.

Parameters:

  • executor (Executor, :io, :fast) —

    Instance of an executor or a name of the global executor. The task is executed on it, default executor remains unchanged.

  • args (Object) —

    arguments which are passed to the task when it's executed. (It might be prepended with other arguments, see the @yeild section).

Yields:

  • (value, *args) —

    to the task.

Yield Returns:

  • will become result of the returned Future. Its returned value becomes #value fulfilling it, raised exception becomes #reason rejecting it.

Returns:



1035
1036
1037
 
# File 'lib/concurrent/promises.rb', line 1035

def then_on(executor, *args, &task)
  ThenPromise.new_blocked_by1(self, @DefaultExecutor, executor, args, &task).future
end

#to_event ⇒ Event

Converts future to event which is resolved when future is resolved by fulfillment or rejection.

Returns:



1211
1212
1213
1214
1215
 
# File 'lib/concurrent/promises.rb', line 1211

def to_event
  event = Promises.resolvable_event
ensure
  chain_resolvable(event)
end

#to_future ⇒ Future

Returns self, since this is a future

Returns:



1219
1220
1221
 
# File 'lib/concurrent/promises.rb', line 1219

def to_future
  self
end

#to_s ⇒ String Also known as: inspect

Returns Short string representation.

Returns:

  • (String) —

    Short string representation.



1224
1225
1226
1227
1228
1229
1230
 
# File 'lib/concurrent/promises.rb', line 1224

def to_s
  if resolved?
    format '%s with %s>', super[0..-2], (fulfilled? ? value : reason).inspect
  else
    super
  end
end

#value(timeout = nil, timeout_value = nil) ⇒ Object, nil, timeout_value

Note:

This function potentially blocks current thread until the Future is resolved. Be careful it can deadlock. Try to chain instead.

Note:

Make sure returned nil is not confused with timeout, no value when rejected, no reason when fulfilled, etc. Use more exact methods if needed, like AbstractEventFuture#wait, #value!, #result, etc.

Return value of the future. Calls AbstractEventFuture#touch.

Parameters:

  • timeout (Numeric) (defaults to: nil) —

    the maximum time in second to wait.

  • timeout_value (Object) (defaults to: nil) —

    a value returned by the method when it times out

Returns:

  • (Object, nil, timeout_value) —

    the value of the Future when fulfilled, timeout_value on timeout, nil on rejection.



939
940
941
942
943
944
945
 
# File 'lib/concurrent/promises.rb', line 939

def value(timeout = nil, timeout_value = nil)
  if wait_until_resolved timeout
    internal_state.value
  else
    timeout_value
  end
end

#value!(timeout = nil, timeout_value = nil) ⇒ Object, nil, timeout_value

Note:

This function potentially blocks current thread until the Future is resolved. Be careful it can deadlock. Try to chain instead.

Note:

Make sure returned nil is not confused with timeout, no value when rejected, no reason when fulfilled, etc. Use more exact methods if needed, like AbstractEventFuture#wait, #value!, #result, etc.

Return value of the future. Calls AbstractEventFuture#touch.

Parameters:

  • timeout (Numeric) (defaults to: nil) —

    the maximum time in second to wait.

  • timeout_value (Object) (defaults to: nil) —

    a value returned by the method when it times out

Returns:

  • (Object, nil, timeout_value) —

    the value of the Future when fulfilled, or nil on rejection, or timeout_value on timeout.

Raises:

  • (Exception) —

    #reason on rejection



986
987
988
989
990
991
992
 
# File 'lib/concurrent/promises.rb', line 986

def value!(timeout = nil, timeout_value = nil)
  if wait_until_resolved! timeout
    internal_state.value
  else
    timeout_value
  end
end

#wait!(timeout = nil) ⇒ self, true, false

Note:

This function potentially blocks current thread until the Future is resolved. Be careful it can deadlock. Try to chain instead.

Wait (block the Thread) until receiver is AbstractEventFuture#resolved?. Calls AbstractEventFuture#touch.

Parameters:

  • timeout (Numeric) (defaults to: nil) —

    the maximum time in second to wait.

Returns:

  • (self, true, false) —

    self implies timeout was not used, true implies timeout was used and it was resolved, false implies it was not resolved within timeout.

Raises:

  • (Exception) —

    #reason on rejection



976
977
978
979
 
# File 'lib/concurrent/promises.rb', line 976

def wait!(timeout = nil)
  result = wait_until_resolved!(timeout)
  timeout ? result : self
end

#with_default_executor(executor) ⇒ Future

Crates new object with same class with the executor set as its new default executor. Any futures depending on it will use the new default executor.

Returns:



1100
1101
1102
 
# File 'lib/concurrent/promises.rb', line 1100

def with_default_executor(executor)
  FutureWrapperPromise.new_blocked_by1(self, executor).future
end

#zip(other) ⇒ Future Also known as: &

Creates a new event or a future which will be resolved when receiver and other are. Returns an event if receiver and other are events, otherwise returns a future. If just one of the parties is Future then the result of the returned future is equal to the result of the supplied future. If both are futures then the result is as described in Concurrent::Promises::FactoryMethods#zip_futures_on.

Returns:



1059
1060
1061
1062
1063
1064
1065
 
# File 'lib/concurrent/promises.rb', line 1059

def zip(other)
  if other.is_a?(Future)
    ZipFuturesPromise.new_blocked_by2(self, other, @DefaultExecutor).future
  else
    ZipFutureEventPromise.new_blocked_by2(self, other, @DefaultExecutor).future
  end
end

#then_ask(actor) ⇒ Future Originally defined in module ActorIntegration

Asks the actor with its value.

Returns:

  • (Future) —

    new future with the response form the actor

#then_channel_push(channel) ⇒ Future Originally defined in module NewChannelIntegration

Returns a future which is fulfilled after the message is pushed to the channel. May take a moment if the channel is full.

Parameters:

  • channel (Channel) —

    to push to.

Returns:

  • (Future) —

    a future which is fulfilled after the message is pushed to the channel. May take a moment if the channel is full.

#then_flat_event(*args, &block) ⇒ Event Originally defined in module FlatShortcuts

Returns:

#then_flat_event_on(executor, *args, &block) ⇒ Event Originally defined in module FlatShortcuts

Returns:

#then_flat_future(*args, &block) ⇒ Future Also known as: then_flat Originally defined in module FlatShortcuts

Returns:

#then_flat_future_on(executor, *args, &block) ⇒ Future Also known as: then_flat_on Originally defined in module FlatShortcuts

Returns: