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# encoding: ascii-8bit
# Copyright 2017 Ball Aerospace & Technologies Corp.
# All Rights Reserved.
#
# This program is free software; you can modify and/or redistribute it
# under the terms of the GNU General Public License
# as published by the Free Software Foundation; version 3 with
# attribution addendums as found in the LICENSE.txt
require 'cosmos/config/config_parser'
require 'cosmos/interfaces/protocols/terminated_protocol'
require 'thread' # For Queue
require 'timeout' # For Timeout::Error
module Cosmos
# Protocol which delineates packets using delimiter characters. Designed for
# text based protocols which expect a command and send a response. The
# protocol handles sending the command and capturing the response.
class TemplateProtocol < TerminatedProtocol
# @param write_termination_characters (see TerminatedProtocol#initialize)
# @param read_termination_characters (see TerminatedProtocol#initialize)
# @param ignore_lines [Integer] Number of newline terminated reads to
# ignore when processing the response
# @param initial_read_delay [Integer] Initial delay when connecting before
# trying to read
# @param response_lines [Integer] Number of newline terminated lines which
# comprise the response
# @param strip_read_termination (see TerminatedProtocol#initialize)
# @param discard_leading_bytes (see TerminatedProtocol#initialize)
# @param sync_pattern (see TerminatedProtocol#initialize)
# @param fill_fields (see TerminatedProtocol#initialize)
# @param response_timeout [Float] Number of seconds to wait before timing out
# when waiting for a response
# @param response_polling_period [Float] Number of seconds to wait between polling
# for a response
# @param raise_exceptions [String] Whether to raise exceptions when errors
# occur in the protocol like unexpected responses or response timeouts.
# @param allow_empty_data [true/false/nil] See Protocol#initialize
def initialize(
write_termination_characters,
read_termination_characters,
ignore_lines = 0,
initial_read_delay = nil,
response_lines = 1,
strip_read_termination = true,
discard_leading_bytes = 0,
sync_pattern = nil,
fill_fields = false,
response_timeout = 5.0,
response_polling_period = 0.02,
raise_exceptions = false,
allow_empty_data = nil
)
super(
write_termination_characters,
read_termination_characters,
strip_read_termination,
discard_leading_bytes,
sync_pattern,
fill_fields,
allow_empty_data)
@response_template = nil
@response_packet = nil
@response_packets = []
@write_block_queue = Queue.new
@ignore_lines = ignore_lines.to_i
@response_lines = response_lines.to_i
@initial_read_delay = ConfigParser.handle_nil(initial_read_delay)
@initial_read_delay = @initial_read_delay.to_f if @initial_read_delay
@response_timeout = ConfigParser.handle_nil(response_timeout)
@response_timeout = @response_timeout.to_f if @response_timeout
@response_polling_period = response_polling_period.to_f
@connect_complete_time = nil
@raise_exceptions = ConfigParser.handle_true_false(raise_exceptions)
end
def reset
super()
@initial_read_delay_needed = true
end
def connect_reset
super()
begin
@write_block_queue.pop(true) while @write_block_queue.length > 0
rescue
end
@connect_complete_time = Time.now + @initial_read_delay if @initial_read_delay
end
def disconnect_reset
super()
@write_block_queue << nil # Unblock the write block queue
end
def read_data(data)
return super(data) if (data.length <= 0)
# Drop all data until the initial_read_delay is complete.
# This gets rid of unused welcome messages,
# prompts, and other junk on initial connections
if @initial_read_delay and @initial_read_delay_needed and @connect_complete_time
return :STOP if Time.now < @connect_complete_time
@initial_read_delay_needed = false
end
super(data)
end
def read_packet(packet)
if @response_template && @response_packet
# If lines make it this far they are part of a response
@response_packets << packet
return :STOP if @response_packets.length < (@ignore_lines + @response_lines)
@ignore_lines.times do
@response_packets.shift
end
response_string = ''
@response_lines.times do
response = @response_packets.shift
response_string << response.buffer
end
# Grab the response packet specified in the command
result_packet = System.telemetry.packet(@interface.target_names[0], @response_packet).clone
result_packet.received_time = nil
result_packet.id_items.each do |item|
result_packet.write_item(item, item.id_value, :RAW)
end
# Convert the response template into a Regexp
response_item_names = []
response_template = @response_template.clone
response_template_items = @response_template.scan(/<.*?>/)
response_template_items.each do |item|
response_item_names << item[1..-2]
response_template.gsub!(item, "(.*)")
end
response_regexp = Regexp.new(response_template)
# Scan the response for the variables in brackets <VARIABLE>
# Write the packet value with each of the values received
response_values = response_string.scan(response_regexp)[0]
if !response_values || (response_values.length != response_item_names.length)
handle_error("#{@interface.name}: Unexpected response: #{response_string}")
else
response_values.each_with_index do |value, i|
begin
result_packet.write(response_item_names[i], value)
rescue => error
handle_error("#{@interface.name}: Could not write value #{value} due to #{error.message}")
break
end
end
end
@response_packets.clear
# Release the write
if @response_template && @response_packet
@write_block_queue << nil
end
return result_packet
else
return packet
end
end
def write_packet(packet)
# Make sure we are past the initial data dropping period
if @initial_read_delay and @initial_read_delay_needed and @connect_complete_time and Time.now < @connect_complete_time
delay_needed = @connect_complete_time - Time.now
sleep(delay_needed) if delay_needed > 0
end
# First grab the response template and response packet (if there is one)
begin
@response_template = packet.read("RSP_TEMPLATE").strip
@response_packet = packet.read("RSP_PACKET").strip
# If the template or packet are empty set them to nil. This allows for
# the user to remove the RSP_TEMPLATE and RSP_PACKET values and avoid
# any response timeouts
if @response_template.empty? || @response_packet.empty?
@response_template = nil
@response_packet = nil
end
rescue
# If there is no response template we set to nil
@response_template = nil
@response_packet = nil
end
# Grab the command template because that is all we eventually send
@template = packet.read("CMD_TEMPLATE")
# Create a new packet to populate with the template
raw_packet = Packet.new(nil, nil)
raw_packet.buffer = @template
raw_packet = super(raw_packet)
return raw_packet if Symbol === raw_packet
data = raw_packet.buffer(false)
# Scan the template for variables in brackets <VARIABLE>
# Read these values from the packet and substitute them in the template
# and in the @response_packet name
@template.scan(/<(.*?)>/).each do |variable|
value = packet.read(variable[0], :RAW).to_s
data.gsub!("<#{variable[0]}>", value)
@response_packet.gsub!("<#{variable[0]}>", value) if @response_packet
end
return raw_packet
end
def post_write_interface(packet, data)
if @response_template && @response_packet
if @response_timeout
response_timeout_time = Time.now + @response_timeout
else
response_timeout_time = nil
end
# Block the write until the response is received
begin
@write_block_queue.pop(true)
rescue
sleep(@response_polling_period)
retry if !response_timeout_time
retry if response_timeout_time and Time.now < response_timeout_time
handle_error("#{@interface.name}: Timeout waiting for response")
end
@response_template = nil
@response_packet = nil
@response_packets.clear
end
return super(packet, data)
end
def handle_error(msg)
Logger.error(msg)
raise msg if @raise_exceptions
end
end
end