class Channel(T)
Overview
A Channel
enables concurrent communication between fibers.
They allow communicating data between fibers without sharing memory and without having to worry about locks, semaphores or other special structures.
channel = Channel(Int32).new
spawn do
channel.send(0)
channel.send(1)
end
channel.receive # => 0
channel.receive # => 1
NOTE Although a Channel(Nil)
or any other nilable types like Channel(Int32?)
are valid
they are discouraged since from certain methods or constructs it receiving a nil
as data
will be indistinguishable from a closed channel.
Defined in:
channel.crConstructors
Class Method Summary
- .receive_first(channels : Enumerable(Channel))
- .receive_first(*channels)
- .send_first(value, channels : Enumerable(Channel)) : Nil
- .send_first(value, *channels) : Nil
Instance Method Summary
-
#close : Bool
Closes the channel.
- #closed? : Bool
-
#inspect(io : IO) : Nil
Appends a String representation of this object which includes its class name, its object address and the values of all instance variables.
- #pretty_print(pp)
-
#receive : T
Receives a value from the channel.
-
#receive? : T | Nil
Receives a value from the channel.
-
#send(value : T) : self
Sends a value to the channel.
Instance methods inherited from class Reference
==(other : self)==(other : JSON::Any)
==(other : YAML::Any)
==(other) ==, dup dup, hash(hasher) hash, initialize initialize, inspect(io : IO) : Nil inspect, object_id : UInt64 object_id, pretty_print(pp) : Nil pretty_print, same?(other : Reference) : Bool
same?(other : Nil) same?, to_s(io : IO) : Nil to_s
Constructor methods inherited from class Reference
new
new,
unsafe_construct(address : Pointer, *args, **opts) : self
unsafe_construct
Class methods inherited from class Reference
pre_initialize(address : Pointer)
pre_initialize
Instance methods inherited from class Object
! : Bool
!,
!=(other)
!=,
!~(other)
!~,
==(other)
==,
===(other : JSON::Any)===(other : YAML::Any)
===(other) ===, =~(other) =~, as(type : Class) as, as?(type : Class) as?, class class, dup dup, hash(hasher)
hash hash, in?(collection : Object) : Bool
in?(*values : Object) : Bool in?, inspect(io : IO) : Nil
inspect : String inspect, is_a?(type : Class) : Bool is_a?, itself itself, nil? : Bool nil?, not_nil!(message)
not_nil! not_nil!, pretty_inspect(width = 79, newline = "\n", indent = 0) : String pretty_inspect, pretty_print(pp : PrettyPrint) : Nil pretty_print, responds_to?(name : Symbol) : Bool responds_to?, tap(&) tap, to_json(io : IO) : Nil
to_json : String to_json, to_pretty_json(indent : String = " ") : String
to_pretty_json(io : IO, indent : String = " ") : Nil to_pretty_json, to_s(io : IO) : Nil
to_s : String to_s, to_yaml(io : IO) : Nil
to_yaml : String to_yaml, try(&) try, unsafe_as(type : T.class) forall T unsafe_as
Class methods inherited from class Object
from_json(string_or_io, root : String)from_json(string_or_io) from_json, from_yaml(string_or_io : String | IO) from_yaml
Constructor Detail
Class Method Detail
Instance Method Detail
Closes the channel.
The method prevents any new value from being sent to / received from the channel.
All fibers blocked in #send
or #receive
will be awakened with Channel::ClosedError
Both awaiting and subsequent calls to #send
will consider the channel closed.
All items successfully sent to the channel can be received, before #receive
considers the channel closed.
Calling #close
on a closed channel does not have any effect.
It returns true
when the channel was successfully closed, or false
if it was already closed.
Appends a String representation of this object which includes its class name, its object address and the values of all instance variables.
class Person
def initialize(@name : String, @age : Int32)
end
end
Person.new("John", 32).inspect # => #<Person:0x10fd31f20 @name="John", @age=32>
Receives a value from the channel. If there is a value waiting, then it is returned immediately. Otherwise, this method blocks until a value is sent to the channel.
Raises ClosedError
if the channel is closed or closes while waiting for receive.
channel = Channel(Int32).new
spawn do
channel.send(1)
end
channel.receive # => 1
Receives a value from the channel. If there is a value waiting, it is returned immediately. Otherwise, this method blocks until a value is sent to the channel.
Returns nil
if the channel is closed or closes while waiting for receive.
Sends a value to the channel.
If the channel has spare capacity, then the method returns immediately.
Otherwise, this method blocks the calling fiber until another fiber calls #receive
on the channel.
Raises ClosedError
if the channel is closed or closes while waiting on a full channel.