Add bin and edit workflow

bin/gems/eventmachine-1.2.7/lib/em/streamer.rb

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+module EventMachine
+  # Streams a file over a given connection. Streaming begins once the object is
+  # instantiated. Typically FileStreamer instances are not reused.
+  #
+  # Streaming uses buffering for files larger than 16K and uses so-called fast file reader (a C++ extension)
+  # if available (it is part of eventmachine gem itself).
+  #
+  # @example
+  #
+  #  module FileSender
+  #    def post_init
+  #      streamer = EventMachine::FileStreamer.new(self, '/tmp/bigfile.tar')
+  #      streamer.callback{
+  #        # file was sent successfully
+  #        close_connection_after_writing
+  #      }
+  #    end
+  #  end
+  #
+  #
+  # @author Francis Cianfrocca
+  class FileStreamer
+    include Deferrable
+
+    # Use mapped streamer for files bigger than 16k
+    MappingThreshold = 16384
+    # Wait until next tick to send more data when 50k is still in the outgoing buffer
+    BackpressureLevel = 50000
+    # Send 16k chunks at a time
+    ChunkSize = 16384
+
+    # @param [EventMachine::Connection] connection
+    # @param [String] filename File path
+    #
+    # @option args [Boolean] :http_chunks (false) Use HTTP 1.1 style chunked-encoding semantics.
+    def initialize connection, filename, args = {}
+      @connection = connection
+      @http_chunks = args[:http_chunks]
+
+      if File.exist?(filename)
+        @size = File.size(filename)
+        if @size <= MappingThreshold
+          stream_without_mapping filename
+        else
+          stream_with_mapping filename
+        end
+      else
+        fail "file not found"
+      end
+    end
+
+    # @private
+    def stream_without_mapping filename
+      if @http_chunks
+        @connection.send_data "#{@size.to_s(16)}\r\n"
+        @connection.send_file_data filename
+        @connection.send_data "\r\n0\r\n\r\n"
+      else
+        @connection.send_file_data filename
+      end
+      succeed
+    end
+    private :stream_without_mapping
+
+    # @private
+    def stream_with_mapping filename
+      ensure_mapping_extension_is_present
+
+      @position = 0
+      @mapping = EventMachine::FastFileReader::Mapper.new filename
+      stream_one_chunk
+    end
+    private :stream_with_mapping
+
+    # Used internally to stream one chunk at a time over multiple reactor ticks
+    # @private
+    def stream_one_chunk
+      loop {
+        if @position < @size
+          if @connection.get_outbound_data_size > BackpressureLevel
+            EventMachine::next_tick {stream_one_chunk}
+            break
+          else
+            len = @size - @position
+            len = ChunkSize if (len > ChunkSize)
+
+            @connection.send_data( "#{len.to_s(16)}\r\n" ) if @http_chunks
+            @connection.send_data( @mapping.get_chunk( @position, len ))
+            @connection.send_data("\r\n") if @http_chunks
+
+            @position += len
+          end
+        else
+          @connection.send_data "0\r\n\r\n" if @http_chunks
+          @mapping.close
+          succeed
+          break
+        end
+      }
+    end
+
+    #
+    # We use an outboard extension class to get memory-mapped files.
+    # It's outboard to avoid polluting the core distro, but that means
+    # there's a "hidden" dependency on it. The first time we get here in
+    # any run, try to load up the dependency extension. User code will see
+    # a LoadError if it's not available, but code that doesn't require
+    # mapped files will work fine without it. This is a somewhat difficult
+    # compromise between usability and proper modularization.
+    #
+    # @private
+    def ensure_mapping_extension_is_present
+      @@fastfilereader ||= (require 'fastfilereaderext')
+    end
+    private :ensure_mapping_extension_is_present
+
+  end # FileStreamer
+end # EventMachine