Class: FiberStream::Flow

Inherits:
Object
  • Object
show all
Defined in:
lib/fiber_stream/flow.rb

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(&attach) ⇒ Flow

Returns a new instance of Flow.



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# File 'lib/fiber_stream/flow.rb', line 215

def initialize(&attach)
  @attach = attach
end

Class Method Details

.async ⇒ Object

Creates a scheduler-backed asynchronous boundary.

The boundary starts its producer on the first downstream demand and requires an installed ‘Fiber.scheduler` at that point. Upstream stages run in a non-blocking producer fiber, downstream stages remain in the caller’s current fiber, and each downstream pull resumes at most one upstream pull. Closing the boundary closes upstream and requests producer cancellation. FiberStream does not depend on Async at runtime.



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# File 'lib/fiber_stream/flow.rb', line 123

def self.async
  new { |upstream| Pull.async(upstream) }
end

.buffer(count) ⇒ Object

Creates a bounded asynchronous buffer.

The buffer starts its producer on the first downstream demand and requires an installed ‘Fiber.scheduler` at that point. It preserves element order, stores at most `count` messages, and closes upstream while requesting producer cancellation when closed. `count` must be a positive Integer. FiberStream does not depend on Async at runtime.

Raises:

  • (TypeError) 


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# File 'lib/fiber_stream/flow.rb', line 134

def self.buffer(count)
  raise TypeError, "count must be an Integer" unless count.is_a?(Integer)
  raise ArgumentError, "count must be positive" unless count.positive?

  new { |upstream| Pull.buffer(upstream, count) }
end

.drop(count) ⇒ Object

Creates a fixed-prefix dropping flow.

The flow discards the first ‘count` upstream elements, then passes later elements through unchanged. `drop(0)` behaves as pass-through. Negative counts raise `ArgumentError`; non-Integer counts raise `TypeError`.

Raises:

  • (TypeError) 


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# File 'lib/fiber_stream/flow.rb', line 83

def self.drop(count)
  raise TypeError, "count must be an Integer" unless count.is_a?(Integer)
  raise ArgumentError, "count must be non-negative" if count.negative?

  new { |upstream| Pull.drop(upstream, count) }
end

.drop_while(&block) ⇒ Object

Creates a predicate-based prefix-dropping flow.

The flow drops leading elements while the block result is truthy. The first false or nil result, and all later elements, pass through unchanged. After that boundary the block is not called again. Exceptions raised by the block fail the stream and are re-raised from ‘Source#run_with`.

Raises:

  • (ArgumentError) 


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# File 'lib/fiber_stream/flow.rb', line 109

def self.drop_while(&block)
  raise ArgumentError, "missing block" unless block

  new { |upstream| Pull.drop_while(upstream, block) }
end

.lines(chomp: true, max_length: nil) ⇒ Object

Creates a line-splitting flow.

The flow accepts String chunks and emits lines split on “n”. By default it chomps the trailing newline and one preceding “r”. ‘max_length` is an optional per-line bytesize limit.

Raises:

  • (TypeError) 


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# File 'lib/fiber_stream/flow.rb', line 146

def self.lines(chomp: true, max_length: nil)
  raise TypeError, "chomp must be true or false" unless [true, false].include?(chomp)
  unless max_length.nil? || max_length.is_a?(Integer)
    raise TypeError, "max_length must be nil or an Integer"
  end
  raise ArgumentError, "max_length must be positive" if max_length&.<= 0

  new { |upstream| Pull.lines(upstream, chomp, max_length) }
end

.map(&block) ⇒ Object

Creates a mapping flow.

The block is called once for each element pulled through this flow. Exceptions raised by the block fail the stream and are re-raised from ‘Source#run_with`.

Raises:

  • (ArgumentError) 


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# File 'lib/fiber_stream/flow.rb', line 10

def self.map(&block)
  raise ArgumentError, "missing block" unless block

  new { |upstream| Pull.map(upstream, block) }
end

.parallel_map(concurrency:, &block) ⇒ Object

Creates an ordered scheduler-backed parallel mapping flow.

The stage starts internal scheduled fibers on first downstream demand and requires an installed ‘Fiber.scheduler` in a non-blocking fiber at that point. At most `concurrency` mapping blocks run at the same time, and at most `concurrency` upstream elements are pulled but not yet emitted downstream. Results are emitted in input order. Closing the boundary closes upstream and requests internal worker cancellation. FiberStream does not depend on Async at runtime.

Raises:

  • (ArgumentError) 


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# File 'lib/fiber_stream/flow.rb', line 25

def self.parallel_map(concurrency:, &block)
  raise ArgumentError, "missing block" unless block
  raise TypeError, "concurrency must be an Integer" unless concurrency.is_a?(Integer)
  raise ArgumentError, "concurrency must be positive" unless concurrency.positive?

  new { |upstream| Pull.parallel_map(upstream, concurrency, block) }
end

.ractor_map(workers:, input_transfer: :copy, output_transfer: :copy, &block) ⇒ Object

Creates an ordered Ractor-backed mapping flow.

The mapper runs inside worker ractors and must be shareable, typically created with ‘Ractor.shareable_proc`. Results are emitted in input order, and at most `workers` upstream elements are pulled but not yet emitted. `input_transfer` and `output_transfer` must be `:copy` or `:move` and are passed to Ractor message sends for element and result transfer.

Raises:

  • (ArgumentError) 


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# File 'lib/fiber_stream/flow.rb', line 40

def self.ractor_map(workers:, input_transfer: :copy, output_transfer: :copy, &block)
  raise ArgumentError, "missing block" unless block
  raise TypeError, "workers must be an Integer" unless workers.is_a?(Integer)
  raise ArgumentError, "workers must be positive" unless workers.positive?

  validate_ractor_transfer_policy!(:input_transfer, input_transfer)
  validate_ractor_transfer_policy!(:output_transfer, output_transfer)
  raise TypeError, "block must be shareable" unless Ractor.shareable?(block)

  new { |upstream| Pull.ractor_map(upstream, workers, input_transfer, output_transfer, block) }
end

.select(&block) ⇒ Object

Creates a filtering flow.

The block is called for upstream elements until it returns a truthy value or upstream completes. Matching elements pass through unchanged. Exceptions raised by the block fail the stream and are re-raised from ‘Source#run_with`.

Raises:

  • (ArgumentError) 


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# File 'lib/fiber_stream/flow.rb', line 58

def self.select(&block)
  raise ArgumentError, "missing block" unless block

  new { |upstream| Pull.select(upstream, block) }
end

.take(count) ⇒ Object

Creates a limiting flow.

The flow emits at most ‘count` elements. `take(0)` completes without pulling upstream and closes upstream on the first downstream demand. After the limit is reached, upstream is closed during the pull that forwards the final element. Negative counts raise `ArgumentError`; non-Integer counts raise `TypeError`.

Raises:

  • (TypeError) 


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# File 'lib/fiber_stream/flow.rb', line 71

def self.take(count)
  raise TypeError, "count must be an Integer" unless count.is_a?(Integer)
  raise ArgumentError, "count must be non-negative" if count.negative?

  new { |upstream| Pull.take(upstream, count) }
end

.take_while(&block) ⇒ Object

Creates a predicate-based limiting flow.

The flow emits leading elements while the block result is truthy. The first false or nil result completes the stream without emitting that element and closes upstream during the same downstream pull. Exceptions raised by the block fail the stream and are re-raised from ‘Source#run_with`.

Raises:

  • (ArgumentError) 


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# File 'lib/fiber_stream/flow.rb', line 97

def self.take_while(&block)
  raise ArgumentError, "missing block" unless block

  new { |upstream| Pull.take_while(upstream, block) }
end

Instance Method Details

#to(sink) ⇒ Object

Returns a sink that runs this flow before ‘sink`.

The composed sink accepts this flow’s input elements and returns the wrapped sink’s materialized value. It closes the attached flow chain after normal completion, failure, or early sink completion.

Raises:

  • (TypeError) 


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# File 'lib/fiber_stream/flow.rb', line 192

def to(sink)
  raise TypeError, "expected FiberStream::Sink" unless sink.is_a?(Sink)

  Sink.__send__(:new) do |stream|
    attached_stream = nil
    primary_error = nil

    begin
      attached_stream = attach(stream)
      sink.__send__(:run, attached_stream)
    rescue StandardError => error
      primary_error = error
      raise
    ensure
      begin
        attached_stream&.close
      rescue StandardError => close_error
        raise close_error unless primary_error
      end
    end
  end
end

#via(flow) ⇒ Object

Returns a reusable flow that applies this flow and then ‘flow`.

Construction is lazy. No upstream stream is attached and no elements are pulled until the composed flow is materialized by a source or sink.

Raises:

  • (TypeError) 


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# File 'lib/fiber_stream/flow.rb', line 168

def via(flow)
  raise TypeError, "expected FiberStream::Flow" unless flow.is_a?(Flow)

  self.class.__send__(:new) do |upstream|
    attached_stream = attach(upstream)

    begin
      flow.__send__(:attach, attached_stream)
    rescue StandardError
      begin
        attached_stream.close
      rescue StandardError
        nil
      end
      raise
    end
  end
end