Class: Async::Scheduler
Overview
Handles scheduling of fibers. Implements the fiber scheduler interface.
Direct Known Subclasses
Instance Attribute Summary
Attributes inherited from Node
#annotation, #children, #head, #parent, #tail
Class Method Summary collapse
-
.supported? ⇒ Boolean
Whether the fiber scheduler is supported.
Instance Method Summary collapse
- #address_resolve(hostname) ⇒ Object
-
#async(*arguments, **options, &block) ⇒ Object
deprecated
Deprecated.
With no replacement.
-
#block(blocker, timeout) ⇒ Object
Invoked when a fiber tries to perform a blocking operation which cannot continue.
- #close ⇒ Object
- #closed? ⇒ Boolean
- #fiber ⇒ Object
-
#initialize(parent = nil, selector: nil) ⇒ Scheduler
constructor
A new instance of Scheduler.
-
#interrupt ⇒ Object
Interrupt the event loop and cause it to exit.
- #io_read(io, buffer, length) ⇒ Object
- #io_wait(io, events, timeout = nil) ⇒ Object
- #io_write(io, buffer, length) ⇒ Object
- #kernel_sleep(duration = nil) ⇒ Object
-
#process_wait(pid, flags) ⇒ Object
Wait for the specified process ID to exit.
-
#push(fiber) ⇒ Object
Schedule a fiber (or equivalent object) to be resumed on the next loop through the reactor.
- #raise(*arguments) ⇒ Object
- #resume(fiber, *arguments) ⇒ Object
-
#run ⇒ Object
Run the reactor until all tasks are finished.
-
#run_once(timeout = nil) ⇒ Object
Run one iteration of the event loop.
- #timeout_after(duration, exception, message, &block) ⇒ Object
- #to_s ⇒ Object
-
#transfer ⇒ Object
Transfer from the calling fiber to the event loop.
- #unblock(blocker, fiber) ⇒ Object
-
#with_timeout(duration, exception = TimeoutError, message = "execution expired", &block) ⇒ Object
Invoke the block, but after the specified timeout, raise TimeoutError in any currenly blocking operation.
-
#yield ⇒ Object
Yield the current fiber and resume it on the next iteration of the event loop.
Methods inherited from Node
#The parent node.=, #annotate, #backtrace, #children?, #consume, #description, #finished?, #print_hierarchy, #root, #stop, #stopped?, #terminate, #transient?, #traverse
Constructor Details
#initialize(parent = nil, selector: nil) ⇒ Scheduler
Returns a new instance of Scheduler.
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# File 'lib/async/scheduler.rb', line 39 def initialize(parent = nil, selector: nil) super(parent) @selector = selector || ::IO::Event::Selector.new(Fiber.current) @interrupted = false @blocked = 0 @timers = ::Timers::Group.new end |
Class Method Details
.supported? ⇒ Boolean
Whether the fiber scheduler is supported.
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# File 'lib/async/scheduler.rb', line 35 def self.supported? true end |
Instance Method Details
#address_resolve(hostname) ⇒ Object
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# File 'lib/async/scheduler.rb', line 151 def address_resolve(hostname) ::Resolv.getaddresses(hostname) end |
#async(*arguments, **options, &block) ⇒ Object
With no replacement.
Start an asynchronous task within the specified reactor. The task will be executed until the first blocking call, at which point it will yield and and this method will return.
This is the main entry point for scheduling asynchronus tasks.
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# File 'lib/async/scheduler.rb', line 259 def async(*arguments, **, &block) task = Task.new(Task.current? || self, **, &block) # I want to take a moment to explain the logic of this. # When calling an async block, we deterministically execute it until the # first blocking operation. We don't *have* to do this - we could schedule # it for later execution, but it's useful to: # - Fail at the point of the method call where possible. # - Execute determinstically where possible. # - Avoid scheduler overhead if no blocking operation is performed. task.run(*arguments) # Console.logger.debug "Initial execution of task #{fiber} complete (#{result} -> #{fiber.alive?})..." return task end |
#block(blocker, timeout) ⇒ Object
Invoked when a fiber tries to perform a blocking operation which cannot continue. A corresponding call #unblock must be performed to allow this fiber to continue.
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# File 'lib/async/scheduler.rb', line 110 def block(blocker, timeout) # $stderr.puts "block(#{blocker}, #{Fiber.current}, #{timeout})" fiber = Fiber.current if timeout timer = @timers.after(timeout) do if fiber.alive? fiber.transfer(false) end end end begin @blocked += 1 @selector.transfer ensure @blocked -= 1 end ensure timer&.cancel end |
#close ⇒ Object
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# File 'lib/async/scheduler.rb', line 51 def close # This is a critical step. Because tasks could be stored as instance variables, and since the reactor is (probably) going out of scope, we need to ensure they are stopped. Otherwise, the tasks will belong to a reactor that will never run again and are not stopped. self.terminate Kernel::raise "Closing scheduler with blocked operations!" if @blocked > 0 # We depend on GVL for consistency: # @guard.synchronize do @selector&.close @selector = nil # end consume end |
#closed? ⇒ Boolean
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# File 'lib/async/scheduler.rb', line 70 def closed? @selector.nil? end |
#fiber ⇒ Object
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# File 'lib/async/scheduler.rb', line 275 def fiber(...) return async(...).fiber end |
#interrupt ⇒ Object
Interrupt the event loop and cause it to exit.
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# File 'lib/async/scheduler.rb', line 79 def interrupt @interrupted = true @selector.wakeup end |
#io_read(io, buffer, length) ⇒ Object
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# File 'lib/async/scheduler.rb', line 177 def io_read(io, buffer, length) @selector.io_read(Fiber.current, io, buffer, length) end |
#io_wait(io, events, timeout = nil) ⇒ Object
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# File 'lib/async/scheduler.rb', line 156 def io_wait(io, events, timeout = nil) fiber = Fiber.current if timeout timer = @timers.after(timeout) do fiber.raise(TimeoutError) end end # Console.logger.info(self, "-> io_wait", fiber, io, events) events = @selector.io_wait(fiber, io, events) # Console.logger.info(self, "<- io_wait", fiber, io, events) return events rescue TimeoutError return false ensure timer&.cancel end |
#io_write(io, buffer, length) ⇒ Object
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# File 'lib/async/scheduler.rb', line 181 def io_write(io, buffer, length) @selector.io_write(Fiber.current, io, buffer, length) end |
#kernel_sleep(duration = nil) ⇒ Object
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# File 'lib/async/scheduler.rb', line 142 def kernel_sleep(duration = nil) if duration self.block(nil, duration) else self.transfer end end |
#process_wait(pid, flags) ⇒ Object
Wait for the specified process ID to exit.
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# File 'lib/async/scheduler.rb', line 191 def process_wait(pid, flags) return @selector.process_wait(Fiber.current, pid, flags) end |
#push(fiber) ⇒ Object
Schedule a fiber (or equivalent object) to be resumed on the next loop through the reactor.
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# File 'lib/async/scheduler.rb', line 96 def push(fiber) @selector.push(fiber) end |
#raise(*arguments) ⇒ Object
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# File 'lib/async/scheduler.rb', line 100 def raise(*arguments) @selector.raise(*arguments) end |
#resume(fiber, *arguments) ⇒ Object
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# File 'lib/async/scheduler.rb', line 104 def resume(fiber, *arguments) @selector.resume(fiber, *arguments) end |
#run ⇒ Object
Run the reactor until all tasks are finished. Proxies arguments to #async immediately before entering the loop, if a block is provided.
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# File 'lib/async/scheduler.rb', line 232 def run(...) Kernel::raise RuntimeError, 'Reactor has been closed' if @selector.nil? initial_task = self.async(...) if block_given? @interrupted = false while self.run_once if @interrupted break end end return initial_task ensure Console.logger.debug(self) {"Exiting run-loop because #{$! ? $! : 'finished'}."} end |
#run_once(timeout = nil) ⇒ Object
Run one iteration of the event loop.
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# File 'lib/async/scheduler.rb', line 198 def run_once(timeout = nil) Kernel::raise "Running scheduler on non-blocking fiber!" unless Fiber.blocking? # If we are finished, we stop the task tree and exit: if self.finished? return false end interval = @timers.wait_interval # If there is no interval to wait (thus no timers), and no tasks, we could be done: if interval.nil? # Allow the user to specify a maximum interval if we would otherwise be sleeping indefinitely: interval = timeout elsif interval < 0 # We have timers ready to fire, don't sleep in the selctor: interval = 0 elsif timeout and interval > timeout interval = timeout end begin @selector.select(interval) rescue Errno::EINTR # Ignore. end @timers.fire # The reactor still has work to do: return true end |
#timeout_after(duration, exception, message, &block) ⇒ Object
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# File 'lib/async/scheduler.rb', line 295 def timeout_after(duration, exception, , &block) with_timeout(duration, exception, ) do |timer| yield duration end end |
#to_s ⇒ Object
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# File 'lib/async/scheduler.rb', line 74 def to_s "\#<#{self.description} #{@children&.size || 0} children (#{stopped? ? 'stopped' : 'running'})>" end |
#transfer ⇒ Object
Transfer from the calling fiber to the event loop.
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# File 'lib/async/scheduler.rb', line 85 def transfer @selector.transfer end |
#unblock(blocker, fiber) ⇒ Object
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# File 'lib/async/scheduler.rb', line 133 def unblock(blocker, fiber) # $stderr.puts "unblock(#{blocker}, #{fiber})" # This operation is protected by the GVL: @selector.push(fiber) @selector.wakeup end |
#with_timeout(duration, exception = TimeoutError, message = "execution expired", &block) ⇒ Object
Invoke the block, but after the specified timeout, raise TimeoutError in any currenly blocking operation. If the block runs to completion before the timeout occurs or there are no non-blocking operations after the timeout expires, the code will complete without any exception.
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# File 'lib/async/scheduler.rb', line 281 def with_timeout(duration, exception = TimeoutError, = "execution expired", &block) fiber = Fiber.current timer = @timers.after(duration) do if fiber.alive? fiber.raise(exception, ) end end yield timer ensure timer.cancel if timer end |
#yield ⇒ Object
Yield the current fiber and resume it on the next iteration of the event loop.
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# File 'lib/async/scheduler.rb', line 90 def yield @selector.yield end |