This module is used to extend sockets and other IO objects, to allow them to be buffered for both read and write. This abstraction makes it quite easy to write a select-based event loop (see Net::SSH::Connection::Session#listen_to).
The general idea is that instead of calling read directly on an IO that has been extended with this module, you call fill (to add pending input to the internal read buffer), and then read_available (to read from that buffer). Likewise, you don’t call write directly, you call enqueue to add data to the write buffer, and then send_pending or wait_for_pending_sends to actually send the data across the wire.
In this way you can easily use the object as an argument to IO.select, calling fill when it is available for read, or send_pending when it is available for write, and then call enqueue and read_available during the idle times.
socket = TCPSocket.new(address, port)
socket.extend(Net::SSH::BufferedIo)
ssh.listen_to(socket)
ssh.loop do
if socket.available > 0
puts socket.read_available
socket.enqueue("response\n")
end
end
Note that this module must be used to extend an instance, and should not be included in a class. If you do want to use it via an include, then you must make sure to invoke the private initialize_buffered_io method in your class’ initialize method:
class Foo < IO
include Net::SSH::BufferedIo
def initialize
initialize_buffered_io
# ...
end
end
Methods
public instance
Included modules
Public instance methods
Returns the number of bytes available to be read from the input buffer. (See read_available.)
# File lib/net/ssh/buffered_io.rb, line 79 79: def available 80: input.available 81: end
Enqueues data in the output buffer, to be written when send_pending is called. Note that the data is not sent immediately by this method!
# File lib/net/ssh/buffered_io.rb, line 85 85: def enqueue(data) 86: output.append(data) 87: end
Tries to read up to n bytes of data from the remote end, and appends the data to the input buffer. It returns the number of bytes read, or 0 if no data was available to be read.
# File lib/net/ssh/buffered_io.rb, line 63 63: def fill(n=8192) 64: input.consume! 65: data = recv(n) 66: debug { "read #{data.length} bytes" } 67: input.append(data) 68: return data.length 69: end
Returns true if there is data waiting in the output buffer, and false otherwise.
# File lib/net/ssh/buffered_io.rb, line 91 91: def pending_write? 92: output.length > 0 93: end
Read up to length bytes from the input buffer. If length is nil, all available data is read from the buffer. (See available.)
# File lib/net/ssh/buffered_io.rb, line 73 73: def read_available(length=nil) 74: input.read(length || available) 75: end
Sends as much of the pending output as possible. Returns true if any data was sent, and false otherwise.
# File lib/net/ssh/buffered_io.rb, line 97 97: def send_pending 98: if output.length > 0 99: sent = send(output.to_s, 0) 100: debug { "sent #{sent} bytes" } 101: output.consume!(sent) 102: return sent > 0 103: else 104: return false 105: end 106: end
Calls send_pending repeatedly, if necessary, blocking until the output buffer is empty.
# File lib/net/ssh/buffered_io.rb, line 110 110: def wait_for_pending_sends 111: send_pending 112: while output.length > 0 113: result = Net::SSH::Compat.io_select(nil, [self]) or next 114: next unless result[1].any? 115: send_pending 116: end 117: end