author | Tero Marttila <terom@paivola.fi> |
Sun, 13 Jan 2013 03:11:25 +0200 | |
changeset 125 | 9925ef5258f1 |
parent 122 | f742c866c765 |
child 138 | e10e473902cb |
permissions | -rw-r--r-- |
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pvl.syslog: import from pvl-collectd
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""" |
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pvl.syslog: import from pvl-collectd
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Non-blocking fifo reads. |
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pvl.syslog: import from pvl-collectd
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""" |
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pvl.syslog: import from pvl-collectd
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pvl.syslog: import from pvl-collectd
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import os |
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pvl.syslog: import from pvl-collectd
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import errno |
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import fcntl |
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pvl.syslog: import from pvl-collectd
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pvl.syslog: import from pvl-collectd
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import logging |
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pvl.syslog: import from pvl-collectd
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fix pvl.verkko-dhcp + pvl.syslog.fifo
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log = logging.getLogger('pvl.syslog.fifo') |
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pvl.syslog: import from pvl-collectd
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class Pipe (object) : |
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""" |
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A pipe from a fd. |
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pvl.syslog: import from pvl-collectd
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pvl.syslog: import from pvl-collectd
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Supports reading lines in a non-blocking fashion. |
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pvl.syslog: import from pvl-collectd
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""" |
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@classmethod |
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def file (cls, file) : |
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""" |
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Create Pipe from file, e.g. sys.stdin. |
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Puts fd into nonblocking mode, which means that the given file will stop working! |
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""" |
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fd = file.fileno() |
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log.debug("%s: %s", file, fd) |
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fl = fcntl.fcntl(fd, fcntl.F_GETFL) |
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fl |= os.O_NONBLOCK |
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fcntl.fcntl(fd, fcntl.F_SETFL, fl) |
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return cls(fd) |
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def __init__ (self, fd) : |
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self._fd = fd |
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self._buf = '' |
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log.debug("pipe: %d", fd) |
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def fileno (self) : |
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""" |
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Fetch the internal fd, failing if we are not open.. |
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pvl.syslog: import from pvl-collectd
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""" |
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pvl.syslog: import from pvl-collectd
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if self._fd is None : |
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raise ValueError("I/O operation on closed pipe: %s" % (self, )) |
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else : |
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return self._fd |
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# XXX: this is almost identical to pvl.socket.ReadStream |
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def read (self, n=512) : |
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""" |
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Read up to n bytes. |
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|
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Returns None if we would block. |
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Raises EOFError on EOF. |
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""" |
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|
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try : |
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buf = os.read(self.fileno(), n) |
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|
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pvl.syslog: import from pvl-collectd
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except OSError as ex : |
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# block? |
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if ex.errno == errno.EAGAIN : |
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# empty |
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buf = None |
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else : |
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raise |
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log.debug("%s: %s", self, buf) |
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if buf is None : |
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return None |
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elif buf : |
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return buf |
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else : |
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raise EOFError() |
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def readline (self) : |
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""" |
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Read and return next waiting line from input. |
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|
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Line is returned without trailing '\n'. |
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|
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Returns None if there is no line available. |
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Raises EOFError if the fifo write end was closed. |
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""" |
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|
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while '\n' not in self._buf : |
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# read chunk |
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read = self.read() |
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|
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if read is None : |
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return None |
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self._buf += read |
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|
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# split out one line |
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line, self._buf = self._buf.split('\n', 1) |
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log.debug("%s", line) |
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return line |
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def readlines (self) : |
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""" |
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112 |
Read any available input, yielding lines. |
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pvl.syslog: import from pvl-collectd
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|
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114 |
Re-opens the FIFO on EOF. |
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116 |
Returns None if there was no more input available, or the fifo was re-opened after EOF. |
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pvl.syslog: import from pvl-collectd
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117 |
""" |
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118 |
|
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pvl.syslog: import from pvl-collectd
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|
119 |
while True : |
122
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# pull line |
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line = self.readline() |
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122 |
|
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if line : |
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yield line |
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125 |
else : |
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126 |
return # block |
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127 |
|
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__iter__ = readlines |
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129 |
|
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def __str__ (self) : |
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return "pipe:{self._fd}".format(self=self) |
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132 |
|
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133 |
class Fifo (Pipe) : |
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134 |
""" |
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|
135 |
A named pipe(7) on the filesystem. |
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|
136 |
|
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137 |
Supports reading lines in a non-blocking fashion, and re-opening on EOF. |
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138 |
""" |
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139 |
|
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140 |
def __init__ (self, path) : |
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self.path = path |
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142 |
Pipe.__init__(self, self._open()) |
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143 |
|
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144 |
def _open (self) : |
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145 |
""" |
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|
146 |
Open the internal fd (nonblocking). |
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147 |
""" |
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|
148 |
|
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149 |
fd = os.open(self.path, os.O_RDONLY | os.O_NONBLOCK) |
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150 |
|
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151 |
log.debug("%s: open: %s", self, fd) |
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|
152 |
|
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153 |
return fd |
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154 |
|
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155 |
def _close (self, fd) : |
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156 |
""" |
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|
157 |
Close. |
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|
158 |
""" |
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changeset
|
159 |
|
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160 |
os.close(fd) |
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|
161 |
|
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|
162 |
def _reopen (self) : |
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163 |
""" |
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|
164 |
Re-open the FIFO in case the writing end was closed, and read gave EOF. |
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|
165 |
""" |
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|
166 |
|
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167 |
self._close(self._fd) |
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|
168 |
self._fd = None |
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|
169 |
self._fd = self._open() |
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|
170 |
|
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|
171 |
def readlines (self) : |
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|
172 |
""" |
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|
173 |
Read any available input, yielding lines. |
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changeset
|
174 |
|
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changeset
|
175 |
Re-opens the FIFO on EOF. |
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changeset
|
176 |
|
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|
177 |
Returns None if there was no more input available, or the fifo was re-opened after EOF. |
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changeset
|
178 |
""" |
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|
179 |
|
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|
180 |
while True : |
31
3e6d0feb115c
pvl.syslog: import from pvl-collectd
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parents:
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|
181 |
try : |
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
diff
changeset
|
182 |
# pull line |
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
diff
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|
183 |
line = self.readline() |
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
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changeset
|
184 |
|
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
diff
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|
185 |
except EOFError : |
122
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186 |
log.debug("%s: EOF: reopen", self) |
31
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pvl.syslog: import from pvl-collectd
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|
187 |
|
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pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
diff
changeset
|
188 |
# reopen and go back to waiting |
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
diff
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|
189 |
self._reopen() |
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
diff
changeset
|
190 |
|
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
diff
changeset
|
191 |
return |
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
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changeset
|
192 |
|
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
diff
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|
193 |
if line is None : |
122
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|
194 |
log.debug("%s: EOF: wait", self) |
f742c866c765
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changeset
|
195 |
return # wait |
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|
196 |
else : |
f742c866c765
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changeset
|
197 |
yield line |
f742c866c765
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changeset
|
198 |
|
31
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
diff
changeset
|
199 |
__iter__ = readlines |
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
diff
changeset
|
200 |
|
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
diff
changeset
|
201 |
def close (self) : |
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
diff
changeset
|
202 |
""" |
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
diff
changeset
|
203 |
Close the fifo. |
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
diff
changeset
|
204 |
""" |
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
diff
changeset
|
205 |
|
122
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|
206 |
self._close(self.fileno()) |
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|
207 |
self._fd = None |
31
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
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changeset
|
208 |
|
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
diff
changeset
|
209 |
def __del__ (self) : |
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
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|
210 |
""" |
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
diff
changeset
|
211 |
Cleanup |
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
diff
changeset
|
212 |
""" |
3e6d0feb115c
pvl.syslog: import from pvl-collectd
Tero Marttila <terom@paivola.fi>
parents:
diff
changeset
|
213 |
|
122
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|
214 |
if self._fd is not None : |
f742c866c765
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|
215 |
self._close(self._fd) |
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|
216 |
self._fd = None |
f742c866c765
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changeset
|
217 |