[trac606] added a new option for bob, --pid-file, to record the PID of bob himself.

mainly intended for testing purposes, so disabled by default.
for testing this feature bind10_test.py is renamed to bind10_test.py.in
and is auto generated by the configure script.

configure.ac

@@ -712,6 +712,7 @@ AC_OUTPUT([doc/version.ent
            src/bin/stats/tests/stats_test
            src/bin/bind10/bind10.py
            src/bin/bind10/tests/bind10_test
+           src/bin/bind10/tests/bind10_test.py
            src/bin/bind10/run_bind10.sh
            src/bin/bindctl/run_bindctl.sh
            src/bin/bindctl/bindctl-source.py

src/bin/bind10/bind10.py.in

@@ -785,6 +785,36 @@ def process_rename(option, opt_str, value, parser):
     """Function that renames the process if it is requested by a option."""
     isc.util.process.rename(value)
 
+def dump_pid(pid_file):
+    """
+    Dump the PID of the current process to the specified file.  If the given
+    file is None this function does nothing.  If the file already exists,
+    the existing content will be removed.  If a system error happens in
+    creating or writing to the file, the corresponding exception will be
+    propagated to the caller.
+    """
+    if pid_file is None:
+        return
+    unlink_pid_file(pid_file)
+    f = open(pid_file, "w")
+    f.write('%d\n' % os.getpid())
+    f.close()
+
+def unlink_pid_file(pid_file):
+    """
+    Remove the given file, which is basically expected to be the PID file
+    created by dump_pid().  If the specified may or may not exist; if it
+    doesn't this function does nothing.  Other system level errors in removing
+    the file will be propagated as the corresponding exception.
+    """
+    if pid_file is None:
+        return
+    try:
+        os.unlink(pid_file)
+    except OSError as error:
+        if error.errno is not errno.ENOENT:
+            raise
+
 def main():
     global options
     global boss_of_bind
@@ -805,6 +835,9 @@ def main():
     parser.add_option("--pretty-name", type="string", action="callback",
                       callback=process_rename,
                       help="Set the process name (displayed in ps, top, ...)")
+    parser.add_option("--pid-file", dest="pid_file", type="string",
+                      default=None,
+                      help="file to dump the PID of the BIND 10 process")
     (options, args) = parser.parse_args()
     if args:
         parser.print_help()
@@ -865,6 +898,7 @@ def main():
         sys.stderr.write("[bind10] Error on startup: %s\n" % startup_result)
         sys.exit(1)
     sys.stdout.write("[bind10] BIND 10 started\n")
+    dump_pid(options.pid_file)
 
     # send "bind10.boot_time" to b10-stats
     time.sleep(1) # wait a second
@@ -918,6 +952,7 @@ def main():
     signal.signal(signal.SIGCHLD, signal.SIG_DFL)
     boss_of_bind.shutdown()
     sys.stdout.write("[bind10] BIND 10 exiting\n");
+    unlink_pid_file(options.pid_file)
     sys.exit(0)
 
 if __name__ == "__main__":

src/bin/bind10/tests/bind10_test.py

@@ -1,4 +1,4 @@
-from bind10 import ProcessInfo, BoB
+from bind10 import ProcessInfo, BoB, dump_pid, unlink_pid_file
 
 # XXX: environment tests are currently disabled, due to the preprocessor
 #      setup that we have now complicating the environment
@@ -412,5 +412,51 @@ class TestStartStopProcessesBob(unittest.TestCase):
 
         bob.config_handler({'start_auth': True, 'start_resolver': True})
 
+class TestPIDFile(unittest.TestCase):
+    def setUp(self):
+        self.pid_file = '@builddir@' + os.sep + 'bind10.pid'
+        if os.path.exists(self.pid_file):
+            os.unlink(self.pid_file)
+
+    def tearDown(self):
+        if os.path.exists(self.pid_file):
+            os.unlink(self.pid_file)
+
+    def check_pid_file(self):
+        # dump PID to the file, and confirm the content is correct
+        dump_pid(self.pid_file)
+        my_pid = os.getpid()
+        self.assertEqual(my_pid, int(open(self.pid_file, "r").read()))
+
+    def test_dump_pid(self):
+        self.check_pid_file()
+
+        # make sure any existing content will be removed
+        open(self.pid_file, "w").write('dummy data\n')
+        self.check_pid_file()
+
+    def test_dump_pid_notexist(self):
+        dummy_data = 'dummy_data\n'
+        open(self.pid_file, "w").write(dummy_data)
+        dump_pid('no_such_pid_file')
+        # the original content of the file should be intact.
+        self.assertEqual(dummy_data, open(self.pid_file, "r").read())
+
+    def test_dump_pid_with_none(self):
+        # Check the behavior of dump_pid() and unlink_pid_file() with None.
+        # This should be no-op.
+        dump_pid(None)
+        self.assertFalse(os.path.exists(self.pid_file))
+
+        dummy_data = 'dummy_data\n'
+        open(self.pid_file, "w").write(dummy_data)
+        unlink_pid_file(None)
+        self.assertEqual(dummy_data, open(self.pid_file, "r").read())
+
+    def test_dump_pid_failure(self):
+        # the attempt to open file will fail, which should result in exception.
+        self.assertRaises(IOError, dump_pid,
+                          'nonexistent_dir' + os.sep + 'bind10.pid')
+
 if __name__ == '__main__':
     unittest.main()