initial edge-triggered epoll model

Coolio and EventMachine only use level-triggered epoll,
but being Rainbows!, we live on the EDGE!

1 files changed, 226 insertions, 0 deletions

diff --git a/lib/rainbows/epoll/client.rb b/lib/rainbows/epoll/client.rb
new file mode 100644
index 0000000..a3ae6db
--- /dev/null
+++ b/lib/rainbows/epoll/client.rb
@@ -0,0 +1,226 @@
+# -*- encoding: binary -*-
+# :enddoc:
+
+module Rainbows::Epoll::Client
+  attr_reader :wr_queue, :state, :epoll_active
+
+  include Rainbows::Epoll::State
+  include Rainbows::EvCore
+  APP = Rainbows.server.app
+  Server = Rainbows::Epoll::Server
+  IN = SleepyPenguin::Epoll::IN | SleepyPenguin::Epoll::ET
+  INLT = SleepyPenguin::Epoll::IN
+  OUT = SleepyPenguin::Epoll::OUT | SleepyPenguin::Epoll::ET
+  KATO = {}
+  KATO.compare_by_identity if KATO.respond_to?(:compare_by_identity)
+  KEEPALIVE_TIMEOUT = Rainbows.keepalive_timeout
+
+  def self.expire
+    if (ot = KEEPALIVE_TIMEOUT) >= 0
+      ot = Time.now - ot
+      KATO.delete_if { |client, time| time < ot and client.timeout! }
+    end
+  end
+
+  # only call this once
+  def epoll_once
+    @wr_queue = [] # may contain String, ResponsePipe, and StreamFile objects
+    @epoll_active = false
+    post_init
+    epoll_run
+    rescue => e
+      handle_error(e)
+  end
+
+  def on_readable
+    case rv = kgio_tryread(16384, RBUF)
+    when String
+      on_read(rv)
+      return if @wr_queue[0] || closed?
+    when :wait_readable
+      KATO[self] = Time.now if :headers == @state
+      return epoll_enable(IN)
+    else
+      break
+    end until :close == @state
+    close unless closed?
+    rescue IOError
+  end
+
+  def app_call # called by on_read()
+    @env[RACK_INPUT] = @input
+    @env[REMOTE_ADDR] = kgio_addr
+    status, headers, body = APP.call(@env.merge!(RACK_DEFAULTS))
+    ev_write_response(status, headers, body, @hp.next?)
+  end
+
+  def write_response_path(status, headers, body, alive)
+    io = body_to_io(body)
+    st = io.stat
+
+    if st.file?
+      defer_file(status, headers, body, alive, io, st)
+    elsif st.socket? || st.pipe?
+      chunk = stream_response_headers(status, headers, alive)
+      stream_response_body(body, io, chunk)
+    else
+      # char or block device... WTF?
+      write_response(status, headers, body, alive)
+    end
+  end
+
+  # used for streaming sockets and pipes
+  def stream_response_body(body, io, chunk)
+    pipe = (chunk ? Rainbows::Epoll::ResponseChunkPipe :
+                    Rainbows::Epoll::ResponsePipe).new(io, self, body)
+    return @wr_queue << pipe if @wr_queue[0]
+    stream_pipe(pipe) or return
+    @wr_queue[0] or @wr_queue << ""
+  end
+
+  def ev_write_response(status, headers, body, alive)
+    if body.respond_to?(:to_path)
+      write_response_path(status, headers, body, alive)
+    else
+      write_response(status, headers, body, alive)
+    end
+    @state = alive ? :headers : :close
+    on_read("") if alive && 0 == @wr_queue.size && 0 != @buf.size
+  end
+
+  def epoll_run
+    if @wr_queue[0]
+      on_writable
+    else
+      KATO.delete self
+      on_readable
+    end
+  end
+
+  def want_more
+    Server::ReRun << self
+  end
+
+  def on_deferred_write_complete
+    :close == @state and return close
+    0 == @buf.size ? on_readable : on_read("")
+  end
+
+  def handle_error(e)
+    msg = Rainbows::Error.response(e) and kgio_trywrite(msg) rescue nil
+    ensure
+      close
+  end
+
+  def write_deferred(obj)
+    Rainbows::StreamFile === obj ? stream_file(obj) : stream_pipe(obj)
+  end
+
+  # writes until our write buffer is empty or we block
+  # returns true if we're done writing everything
+  def on_writable
+    obj = @wr_queue.shift
+
+    case rv = String === obj ? kgio_trywrite(obj) : write_deferred(obj)
+    when nil
+      obj = @wr_queue.shift or return on_deferred_write_complete
+    when String
+      obj = rv # retry
+    when :wait_writable # Strings and StreamFiles only
+      @wr_queue.unshift(obj)
+      epoll_enable(OUT)
+      return
+    when :deferred
+      return
+    end while true
+    rescue => e
+      handle_error(e)
+  end
+
+  # this returns an +Array+ write buffer if blocked
+  def write(buf)
+    unless @wr_queue[0]
+      case rv = kgio_trywrite(buf)
+      when nil
+        return # all written
+      when String
+        buf = rv # retry
+      when :wait_writable
+        epoll_enable(OUT)
+        break # queue
+      end while true
+    end
+    @wr_queue << buf.dup # >3-word 1.9 strings are copy-on-write
+  end
+
+  def close
+    @wr_queue.each { |x| x.respond_to?(:close) and x.close rescue nil }
+    super
+    KATO.delete(self)
+    Server.decr
+  end
+
+  def timeout!
+    close
+    true
+  end
+
+  def defer_file(status, headers, body, alive, io, st)
+    if r = sendfile_range(status, headers)
+      status, headers, range = r
+      write_headers(status, headers, alive)
+      range and defer_file_stream(range[0], range[1], io, body)
+    else
+      write_headers(status, headers, alive)
+      defer_file_stream(0, st.size, io, body)
+    end
+  end
+
+  # returns +nil+ on EOF, :wait_writable if the client blocks
+  def stream_file(sf) # +sf+ is a Rainbows::StreamFile object
+    begin
+      sf.offset += (n = sendfile_nonblock(sf, sf.offset, sf.count))
+      0 == (sf.count -= n) and return sf.close
+    rescue Errno::EAGAIN
+      return :wait_writable
+    rescue
+      sf.close
+      raise
+    end while true
+  end
+
+  def defer_file_stream(offset, count, io, body)
+    sf = Rainbows::StreamFile.new(offset, count, io, body)
+    unless @wr_queue[0]
+      stream_file(sf) or return
+    end
+    @wr_queue << sf
+    epoll_enable(OUT)
+  end
+
+  # this alternates between a push and pull model from the pipe -> client
+  # to avoid having too much data in userspace on either end.
+  def stream_pipe(pipe)
+    case buf = pipe.tryread
+    when String
+      if Array === write(buf)
+        # client is blocked on write, client will pull from pipe later
+        pipe.epoll_disable
+        @wr_queue << pipe
+        epoll_enable(OUT)
+        return :deferred
+      end
+      # continue looping...
+    when :wait_readable
+      # pipe blocked on read, let the pipe push to the client in the future
+      epoll_disable
+      pipe.epoll_enable(IN)
+      return :deferred
+    else # nil => EOF
+      return pipe.close # nil
+    end while true
+    rescue => e
+      pipe.close
+      raise
+  end
+end