Class: WAB::IO::Engine

Inherits:
Object
  • Object
show all
Defined in:
lib/wab/io/engine.rb

Instance Method Summary collapse

Constructor Details

#initialize(shell, tcnt) ⇒ Engine

Starts the engine by creating a listener on STDIN. Processing threads are also created to handle the processing of requests.

tcnt

processing thread count



13
14
15
16
17
18
19
20
21
22
 
# File 'lib/wab/io/engine.rb', line 13

def initialize(shell, tcnt)
  @shell = shell
  @last_rid = 0
  @pending = {}
  @lock = Thread::Mutex.new
  @queue = Queue.new
  tcnt = 1 if 0 >= tcnt
  @tcnt = tcnt
  @timeout_thread = nil
end

Instance Method Details

#process_msg(native) ⇒ Object

return false to exit loop



111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
 
# File 'lib/wab/io/engine.rb', line 111

def process_msg(native)
  # exit loop if an interrupt (api less than 0)
  return false if native[:api] < 0

  rid = native[:rid]
  body = native[:body]
  return send_error(rid, 'No body in request.') if body.nil?

  data = @shell.data(body, false)
  data.detect
  controller = @shell.controller(data)
  return send_error(rid, 'No handler found.') if controller.nil?

  reply_body = nil
  op = body[:op]
  path = body[:path]
  query = body[:query]
  begin
    if 'NEW' == op && controller.respond_to?(:create)
      log_operation_with_body('controller.create', path, query, body) if @shell.info?
      reply_body = controller.create(path, query, data.get(:content))
    elsif 'GET' == op && controller.respond_to?(:read)
      log_operation('controller.read', path, query) if @shell.info?
      reply_body = controller.read(path, query)
    elsif 'DEL' == op && controller.respond_to?(:delete)
      log_operation('controller.delete', path, query) if @shell.info?
      reply_body = controller.delete(path, query)
    elsif 'MOD' == op && controller.respond_to?(:update)
      log_operation_with_body('controller.update', path, query, body) if @shell.info?
      reply_body = controller.update(path, query, data.get(:content))
    else
      reply_body = controller.handle(data)
    end
  rescue Exception => e
    return send_error(rid, "#{e.class}: #{e.message}", e.backtrace)
  end
  # If reply_body is nil then it is async.
  unless reply_body.nil?
    reply_body = reply_body.native if reply_body.is_a?(WAB::Data)
    msg = {rid: rid, api: 2, body: reply_body}
    @shell.info("=> view: #{Oj.dump(msg, mode: :wab)}") if @shell.info?
    $stdout.puts(@shell.data(msg).json)
    $stdout.flush
  end
  true
end

#request(tql, timeout) ⇒ Object

Send request to the model portion of the system.

tql

the body of the message which should be JSON-TQL as a native Hash



78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
 
# File 'lib/wab/io/engine.rb', line 78

def request(tql, timeout)
  call = Call.new(timeout)

  @lock.synchronize {
    @last_rid += 1
    call.rid = @last_rid.to_s
    @pending[call.rid] = call
  }

  msg = {rid: call.rid, api: 3, body: tql}
  @shell.info("=> model: #{Oj.dump(msg, mode: :wab)}") if @shell.info?
  data = @shell.data(msg, true)
  # Send the message. Make sure to flush to assure it gets sent.
  $stdout.puts(data.json)
  $stdout.flush

  # Wait for either the response to arrive or for a timeout. In both
  # cases #run should be called on the thread. Sleep is used instead of
  # stop to avoid a race condition where a response arrives before the
  # thread is stopped.
  sleep(0.1) while call.result.nil?
  call.result
end

#send_error(rid, msg, bt = nil) ⇒ Object 



102
103
104
105
106
107
108
 
# File 'lib/wab/io/engine.rb', line 102

def send_error(rid, msg, bt=nil)
  body = { code: -1, error: msg }
  body[:backtrace] = bt unless bt.nil?
  $stdout.puts(@shell.data({rid: rid, api: 2, body: body}).json)
  $stdout.flush
  true
end

#shutdown(msg) ⇒ Object 



68
69
70
71
72
73
 
# File 'lib/wab/io/engine.rb', line 68

def shutdown(msg)
  # TBD kill timeout thread
  Thread.kill(@timeout_thread)
  # tell processing threads to shutdown.
  @tcnt.times { @queue.push(msg) }
end

#start ⇒ Object 



24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
 
# File 'lib/wab/io/engine.rb', line 24

def start()
  proc_threads = []
  @tcnt.times {
    proc_threads << Thread.new {
      while true
        begin
          break unless process_msg(@queue.pop)
        rescue Exception => e
          $stderr.puts WAB::Impl.format_error(e)
        end
      end
    }
  }
  @timeout_thread = Thread.new { timeout_check }

  Oj.load($stdin, mode: :wab, symbol_keys: true) { |msg|
    api = msg[:api]
    @shell.info("=> controller #{Oj.dump(msg, mode: :wab)}") if @shell.info?
    case api
    when 1
      @queue.push(msg)
    when 4
      rid = msg[:rid]
      call = nil
      @lock.synchronize {
        call = @pending.delete(rid)
      }
      unless call.nil?
        call.result = msg[:body]
        call.thread.run
      end
    when -2, -3, -6, -15
      shutdown(msg)
      break
    when -9
      Thread.kill(@timeout_thread)
      proc_threads.each { |t| Thread.kill(t) }
      Process.exit(0)
    else
      $stderr.puts WAB::Impl.format_error("Invalid api value (#{api}) in message.")
    end
  }
end

#timeout_check ⇒ Object 



158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
 
# File 'lib/wab/io/engine.rb', line 158

def timeout_check()
  while true
    sleep(0.5)
    timed_out = []
    now = Time.now
    @lock.synchronize {
      @pending.delete_if { |_rid,call|
        if call.giveup <= now
          timed_out << call
          true
        else
          false
        end
      }
    }
    timed_out.each { |call|
      body = { code: -1, error: "Timed out waiting for #{call.rid}." }
      unless call.nil?
        call.result = body
        call.thread.run
      end
    }
  end
end