Module: Daemonize

Defined in:
lib/daemons/daemonize.rb

Constant Summary collapse

VERSION = 
"0.1.1m"

Class Method Summary collapse

Class Method Details

.call_as_daemon(block, logfile_name = nil, app_name = nil) ⇒ Object 



142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
 
# File 'lib/daemons/daemonize.rb', line 142

def call_as_daemon(block, logfile_name = nil, app_name = nil)
  rd, wr = IO.pipe
  
  if tmppid = safefork
    # parent
    wr.close
    pid = rd.read.to_i
    rd.close
    
    Process.waitpid(tmppid)
    
    return pid
  else
    # child
    
    rd.close
    
    # Detach from the controlling terminal
    unless sess_id = Process.setsid
      raise Daemons.RuntimeException.new('cannot detach from controlling terminal')
    end

    # Prevent the possibility of acquiring a controlling terminal
    #if oldmode.zero?
      trap 'SIGHUP', 'IGNORE'
      exit if pid = safefork
    #end

    wr.write Process.pid
    wr.close
    
    $0 = app_name if app_name
    
    Dir.chdir "/"   # Release old working directory
    File.umask 0000 # Insure sensible umask

    # Make sure all file descriptors are closed
    ObjectSpace.each_object(IO) do |io|
      unless [STDIN, STDOUT, STDERR].include?(io)
        begin
          unless io.closed?
            io.close
          end
        rescue ::Exception
        end
      end
    end

    redirect_io(logfile_name)  
  
    block.call
    
    exit
  end
end

.daemonize(logfile_name = nil, app_name = nil) ⇒ Object

This method causes the current running process to become a daemon



201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
 
# File 'lib/daemons/daemonize.rb', line 201

def daemonize(logfile_name = nil, app_name = nil)
  srand # Split rand streams between spawning and daemonized process
  safefork and exit # Fork and exit from the parent

  # Detach from the controlling terminal
  unless sess_id = Process.setsid
    raise Daemons.RuntimeException.new('cannot detach from controlling terminal')
  end

  # Prevent the possibility of acquiring a controlling terminal
  #if oldmode.zero?
    trap 'SIGHUP', 'IGNORE'
    exit if pid = safefork
  #end

  $0 = app_name if app_name
  
  Dir.chdir "/"   # Release old working directory
  File.umask 0000 # Insure sensible umask

  # Make sure all file descriptors are closed
  ObjectSpace.each_object(IO) do |io|
    unless [STDIN, STDOUT, STDERR].include?(io)
      begin
        unless io.closed?
          io.close
        end
      rescue ::Exception
      end
    end
  end

  redirect_io(logfile_name)
  
  #return oldmode ? sess_id : 0   # Return value is mostly irrelevant
  return sess_id
end

.redirect_io(logfile_name) ⇒ Object

Free file descriptors and point them somewhere sensible STDOUT/STDERR should go to a logfile



244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
 
# File 'lib/daemons/daemonize.rb', line 244

def redirect_io(logfile_name)
  begin; STDIN.reopen "/dev/null"; rescue ::Exception; end       
   
  if logfile_name
    begin
      STDOUT.reopen logfile_name, "a" 
      STDOUT.sync = true
    rescue ::Exception
      begin; STDOUT.reopen "/dev/null"; rescue ::Exception; end
    end
  else
    begin; STDOUT.reopen "/dev/null"; rescue ::Exception; end
  end
  
  begin; STDERR.reopen STDOUT; rescue ::Exception; end
  STDERR.sync = true
end

.safefork ⇒ Object

Try to fork if at all possible retrying every 5 sec if the maximum process limit for the system has been reached



97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
 
# File 'lib/daemons/daemonize.rb', line 97

def safefork
  tryagain = true

  while tryagain
    tryagain = false
    begin
      if pid = fork
        return pid
      end
    rescue Errno::EWOULDBLOCK
      sleep 5
      tryagain = true
    end
  end
end

.simulate(logfile_name = nil) ⇒ Object 



115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
 
# File 'lib/daemons/daemonize.rb', line 115

def simulate(logfile_name = nil)
  # NOTE: STDOUT and STDERR will not be redirected to the logfile, because in :ontop mode, we normally want to see the output
  
  Dir.chdir "/"   # Release old working directory
  File.umask 0000 # Insure sensible umask

  # Make sure all file descriptors are closed
  ObjectSpace.each_object(IO) do |io|
    unless [STDIN, STDOUT, STDERR].include?(io)
      begin
        unless io.closed?
          io.close
        end
      rescue ::Exception
      end
    end
  end

  # Free file descriptors and
  # point them somewhere sensible
  # STDOUT/STDERR should go to a logfile
  
  begin; STDIN.reopen "/dev/null"; rescue ::Exception; end       
end