# This file is Copyright (c) 2010 by the GPSD project # BSD terms apply: see the file COPYING in the distribution root for details. """ gpsfake.py -- classes for creating a controlled test environment around gpsd. The gpsfake(1) regression tester shipped with GPSD is a trivial wrapper around this code. For a more interesting usage example, see the valgrind-audit script shipped with the GPSD code. To use this code, start by instantiating a TestSession class. Use the prefix argument if you want to run the daemon under some kind of run-time monitor like valgrind or gdb. Here are some particularly useful possibilities: valgrind --tool=memcheck --gen-suppressions=yes --leak-check=yes Run under Valgrind, checking for malloc errors and memory leaks. xterm -e gdb -tui --args Run under gdb, controlled from a new xterm. You can use the options argument to pass in daemon options; normally you will use this to set the debug-logging level. On initialization, the test object spawns an instance of gpsd with no devices or clients attached, connected to a control socket. TestSession has methods to attach and detch fake GPSes. The TestSession class simulates GPS devices for you with objects composed from a pty and a class instance that cycles sentences into the master side from some specified logfile; gpsd reads the slave side. A fake GPS is identified by the string naming its slave device. TestSession also has methods to start and end client sessions. Daemon responses to a client are fed to a hook function which, by default, discards them. You can change the hook to sys.stdout.write() to dump responses to standard output (this is what the gpsfake executable does) or do something more exotic. A client session is identified by a small integer that counts the number of client session starts. There are a couple of convenience methods. TestSession.wait() does nothing, allowing a specified number of seconds to elapse. TestSession.send() ships commands to an open client session. TestSession does not currently capture the daemon's log output. It is run with -N, so the output will go to stderr (along with, for example, Valgrind notifications). Each FakeGPS instance tries to packetize the data from the logfile it is initialized with. It uses the same packet-getter as the daemon. Exception: if there is a Delay-Cookie line in a header comment, that delimiter is used to split up the test load. The TestSession code maintains a run queue of FakeGPS and gps.gs (client- session) objects. It repeatedly cycles through the run queue. For each client session object in the queue, it tries to read data from gpsd. For each fake GPS, it sends one line or packet of stored data. When a fake-GPS's go predicate becomes false, the fake GPS is removed from the run queue. There are two ways to use this code. The more deterministic is non-threaded mode: set up your client sessions and fake GPS devices, then call the run() method. The run() method will terminate when there are no more objects in the run queue. Note, you must have created at least one fake client or fake GPS before calling run(), otherwise it will terminate immediately. To allow for adding and removing clients while the test is running, run in threaded mode by calling the start() method. This simply calls the run method in a subthread, with locking of critical regions. """ import os, sys, time, signal, pty, termios # fcntl, array, struct import exceptions, threading, socket, select import gps import packet as sniffer # The two magic numbers below have to be derived from observation. If # they're too high you'll slow the tests down a lot. If they're too low # you'll get random spurious regression failures that usually look # like lines missing from the end of the test output relative to the # check file. The need for them may be symptomatic of race conditions # in the pty layer or elsewhere. # WRITE_PAD: Define a per-line delay on writes so we won't spam the # buffers in the pty layer or gpsd itself. Values smaller than the # system timer tick don't make any difference here. # CLOSE_DELAY: We delay briefly after a GPS source is exhausted before # removing it. This should give its subscribers time to get gpsd's # response before we call the cleanup code. Note that using fractional # seconds in CLOSE_DELAY may have no effect; Python time.time() # returns a float value, but it is not guaranteed by Python that the C # implementation underneath will return with precision finer than 1 # second. (Linux and *BSD return full precision.) # Field reports on minima: # # Eric Raymond runningLinux 3.11.0 on an Intel Core Duo at 2.66GHz. # WRITE_PAD = 0.0 / CLOSE_DELAY = 0.1 Works, 112s real # WRITE_PAD = 0.0 / CLOSE_DELAY = 0.05 Fails # # Michael Tatarinov running ?? on a Raspberry Pi: # WRITE_PAD = 0.0 / CLOSE_DELAY = 0.05 Works, 344s real # WRITE_PAD = 0.0 / CLOSE_DELAY = 0.0 Fails, 339s real # # Hal Murray running NetBSD 6.1.2 on an Intel(R) Celeron(R) CPU 2.80GHz # WRITE_PAD = 0.0 / CLOSE_DELAY = 0.4 Works, takes 688.69s real # WRITE_PAD = 0.0 / CLOSE_DELAY = 0.3 Fails tcp-torture.log, 677.53s real # # Greg Troxel running NetBSD 6 on a Core i5 (i386, 4 cpus) 2.90GHz. # WRITE_PAD = 0.001 / CLOSE_DELAY = 0.2 had failures (645s) # WRITE_PAD = 0.001 / CLOSE_DELAY = 0.4 had failures (662s) # WRITE_PAD = 0.000 / CLOSE_DELAY = 0.8 had 69/89 failures (148s) # WRITE_PAD = 0.001 / CLOSE_DELAY = 0.8 all tests passed (697s) # WRITE_PAD = 0.004 / CLOSE_DELAY = 0.8 all tests passed (737s) # # Greg Troxel running NetBSD 5 on a Core 2 Duo E8500 (amd64, 2 cpus) 3.167GHz. # WRITE_PAD = 0.004 / CLOSE_DELAY = 0.8 had 7/89 failures (730s) # WRITE_PAD = 0.004 / CLOSE_DELAY = 2.0 had 3/89 failures (757s) # WRITE_PAD = 0.010 / CLOSE_DELAY = 2.0 had 32/89 failures (755s) # WRITE_PAD = 0.004 / CLOSE_DELAY = 4.0 had 13/89 failures (795s) # WRITE_PAD = 0.004 / CLOSE_DELAY = 8.0 had 27/89 failures (872s) # WRITE_PAD = 0.100 / CLOSE_DELAY = 8.0 had 9/89 failures (3519s) # WRITE_PAD = 0.100 / CLOSE_DELAY = 8.0 had 7/89 failures (3539s) # WRITE_PAD = 0.200 / CLOSE_DELAY = 8.0 all tests passed (6456s) # WRITE_PAD = 0.200 / CLOSE_DELAY = 0.8 all tests passed (6310s) # # Greg Troxel running OS X 10.9 on a Core i7 (2 cpus) 1.7 GHz. # WRITE_PAD = 0.01 / CLOSE_DELAY = 4 had 81/89 failures (767s) # WRITE_PAD = 0.01 / CLOSE_DELAY = 10 had 81/89 failures (1288s) # WRITE_PAD = 0.03 / CLOSE_DELAY = 1 all tests passed (1111s) # WRITE_PAD = 0.03 / CLOSE_DELAY = 2 all tests passed (1194s) # WRITE_PAD = 0.05 / CLOSE_DELAY = 2 all tests passed (1780s) # WRITE_PAD = 0.1 / CLOSE_DELAY = 2 all tests passed (3248s) # WRITE_PAD = 1 / CLOSE_DELAY = 2 all tests passed (29665s) # WRITE_PAD = 1 / CLOSE_DELAY = 10 all tests passed (30362s) # examples are "# sys.platform platform.platform()" if sys.platform.startswith("linux"): WRITE_PAD = 0.0 CLOSE_DELAY = 0.1 elif sys.platform.startswith("freebsd"): WRITE_PAD = 0.001 CLOSE_DELAY = 0.4 elif sys.platform.startswith("netbsd5"): WRITE_PAD = 0.200 CLOSE_DELAY = 0.8 elif sys.platform.startswith("netbsd"): WRITE_PAD = 0.004 CLOSE_DELAY = 0.8 elif sys.platform.startswith("darwin"): # darwin Darwin-13.4.0-x86_64-i386-64bit WRITE_PAD = 0.03 CLOSE_DELAY = 1 else: WRITE_PAD = 0.004 CLOSE_DELAY = 0.8 # Additional delays in slow mode WRITE_PAD_SLOWDOWN = 0.01 CLOSE_DELAY_SLOWDOWN = 2.0 class TestLoadError(exceptions.Exception): def __init__(self, msg): exceptions.Exception.__init__(self) self.msg = msg class TestLoad: "Digest a logfile into a list of sentences we can cycle through." def __init__(self, logfp, predump=False, slow=False): self.sentences = [] # This is the interesting part if type(logfp) == type(""): logfp = open(logfp, "r") self.name = logfp.name self.logfp = logfp self.predump = predump self.type = None self.sourcetype = "pty" self.serial = None self.delay = WRITE_PAD if slow: self.delay += WRITE_PAD_SLOWDOWN self.delimiter = None # Stash away a copy in case we need to resplit text = logfp.read() logfp = open(logfp.name) # Grab the packets in the normal way getter = sniffer.new() #gps.packet.register_report(reporter) type_latch = None commentlen = 0 while True: (plen, ptype, packet, _counter) = getter.get(logfp.fileno()) if plen <= 0: break elif ptype == sniffer.COMMENT_PACKET: commentlen += len(packet) # Some comments are magic if "Serial:" in packet: # Change serial parameters packet = packet[1:].strip() try: (_xx, baud, params) = packet.split() baud = int(baud) if params[0] in ('7', '8'): databits = int(params[0]) else: raise ValueError if params[1] in ('N', 'O', 'E'): parity = params[1] else: raise ValueError if params[2] in ('1', '2'): stopbits = int(params[2]) else: raise ValueError except (ValueError, IndexError): raise TestLoadError("bad serial-parameter spec in %s"%\ self.name) self.serial = (baud, databits, parity, stopbits) elif "Transport: UDP" in packet: self.sourcetype = "UDP" elif "Transport: TCP" in packet: self.sourcetype = "TCP" elif "Delay-Cookie:" in packet: if packet.startswith("#"): packet = packet[1:] try: (_dummy, self.delimiter, delay) = packet.strip().split() self.delay = float(delay) except ValueError: raise TestLoadError("bad Delay-Cookie line in %s"%\ self.name) self.resplit = True else: if type_latch is None: type_latch = ptype if self.predump: print repr(packet) if not packet: raise TestLoadError("zero-length packet from %s"%\ self.name) self.sentences.append(packet) # Look at the first packet to grok the GPS type self.textual = (type_latch == sniffer.NMEA_PACKET) if self.textual: self.legend = "gpsfake: line %d: " else: self.legend = "gpsfake: packet %d" # Maybe this needs to be split on different delimiters? if self.delimiter is not None: self.sentences = text[commentlen:].split(self.delimiter) class PacketError(exceptions.Exception): def __init__(self, msg): exceptions.Exception.__init__(self) self.msg = msg class FakeGPS: def __init__(self, testload, progress=None): self.testload = testload self.progress = progress self.go_predicate = lambda: True self.readers = 0 self.index = 0 self.progress("gpsfake: %s provides %d sentences\n" % (self.testload.name, len(self.testload.sentences))) def write(self, line): "Throw an error if this superclass is ever instantiated." raise ValueError, line def feed(self): "Feed a line from the contents of the GPS log to the daemon." line = self.testload.sentences[self.index % len(self.testload.sentences)] if "%Delay:" in line: # Delay specified number of seconds delay = line.split()[1] time.sleep(int(delay)) # self.write has to be set by the derived class self.write(line) if self.progress: self.progress("gpsfake: %s feeds %d=%s\n" % (self.testload.name, len(line), repr(line))) time.sleep(self.testload.delay) self.index += 1 class FakePTY(FakeGPS): "A FakePTY is a pty with a test log ready to be cycled to it." def __init__(self, testload, speed=4800, databits=8, parity='N', stopbits=1, progress=None): FakeGPS.__init__(self, testload, progress) # Allow Serial: header to be overridden by explicit speed. if self.testload.serial: (speed, databits, parity, stopbits) = self.testload.serial self.speed = speed baudrates = { 0: termios.B0, 50: termios.B50, 75: termios.B75, 110: termios.B110, 134: termios.B134, 150: termios.B150, 200: termios.B200, 300: termios.B300, 600: termios.B600, 1200: termios.B1200, 1800: termios.B1800, 2400: termios.B2400, 4800: termios.B4800, 9600: termios.B9600, 19200: termios.B19200, 38400: termios.B38400, 57600: termios.B57600, 115200: termios.B115200, 230400: termios.B230400, } (self.fd, self.slave_fd) = pty.openpty() self.byname = os.ttyname(self.slave_fd) (iflag, oflag, cflag, lflag, ispeed, ospeed, cc) = termios.tcgetattr(self.slave_fd) cc[termios.VMIN] = 1 cflag &= ~(termios.PARENB | termios.PARODD | termios.CRTSCTS) cflag |= termios.CREAD | termios.CLOCAL iflag = oflag = lflag = 0 iflag &=~ (termios.PARMRK | termios.INPCK) cflag &=~ (termios.CSIZE | termios.CSTOPB | termios.PARENB | termios.PARODD) if databits == 7: cflag |= termios.CS7 else: cflag |= termios.CS8 if stopbits == 2: cflag |= termios.CSTOPB # Warning: attempting to set parity makes Fedora lose its cookies if parity == 'E': iflag |= termios.INPCK cflag |= termios.PARENB elif parity == 'O': iflag |= termios.INPCK cflag |= termios.PARENB | termios.PARODD ispeed = ospeed = baudrates[speed] try: termios.tcsetattr(self.slave_fd, termios.TCSANOW, [iflag, oflag, cflag, lflag, ispeed, ospeed, cc]) except termios.error: raise TestLoadError("error attempting to set serial mode to %s %s%s%s" \ % (speed, databits, parity, stopbits)) def read(self): "Discard control strings written by gpsd." # A tcflush implementation works on Linux but fails on OpenBSD 4. termios.tcflush(self.fd, termios.TCIFLUSH) # Alas, the FIONREAD version also works on Linux and fails on OpenBSD. #try: # buf = array.array('i', [0]) # fcntl.ioctl(self.master_fd, termios.FIONREAD, buf, True) # n = struct.unpack('i', buf)[0] # os.read(self.master_fd, n) #except IOError: # pass def write(self, line): os.write(self.fd, line) def drain(self): "Wait for the associated device to drain (e.g. before closing)." termios.tcdrain(self.fd) class FakeTCP(FakeGPS): "A TCP serverlet with a test log ready to be cycled to it." def __init__(self, testload, host, port, progress=None): FakeGPS.__init__(self, testload, progress) self.host = host self.port = int(port) self.byname = "tcp://" + host + ":" + str(port) self.dispatcher = socket.socket(socket.AF_INET, socket.SOCK_STREAM) # This magic prevents "Address already in use" errors after # we release the socket. self.dispatcher.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) self.dispatcher.bind((self.host, self.port)) self.dispatcher.listen(5) self.readables = [self.dispatcher] def read(self): "Handle connection requests and data." readable, _writable, _errored = select.select(self.readables, [], [], 0) for s in readable: if s == self.dispatcher: # Connection request client_socket, _address = s.accept() self.readables = [client_socket] self.dispatcher.close() else: # Incoming data data = s.recv(1024) if not data: s.close() self.readables.remove(s) def write(self, line): "Send the next log packet to everybody connected." for s in self.readables: if s != self.dispatcher: s.send(line) def drain(self): "Wait for the associated device(s) to drain (e.g. before closing)." for s in self.readables: if s != self.dispatcher: s.shutdown(socket.SHUT_RDWR) class FakeUDP(FakeGPS): "A UDP broadcaster with a test log ready to be cycled to it." def __init__(self, testload, ipaddr, port, progress=None): FakeGPS.__init__(self, testload, progress) self.ipaddr = ipaddr self.port = port self.byname = "udp://" + ipaddr + ":" + str(port) self.sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) def read(self): "Discard control strings written by gpsd." pass def write(self, line): self.sock.sendto(line, (self.ipaddr, int(self.port))) def drain(self): "Wait for the associated device to drain (e.g. before closing)." pass # shutdown() fails on UDP class DaemonError(exceptions.Exception): def __init__(self, msg): exceptions.Exception.__init__(self) self.msg = msg def __str__(self): return repr(self.msg) class DaemonInstance: "Control a gpsd instance." def __init__(self, control_socket=None): self.sockfile = None self.pid = None self.tmpdir = os.environ.get('TMPDIR', '/tmp') if control_socket: self.control_socket = control_socket else: self.control_socket = "%s/gpsfake-%d.sock" % (self.tmpdir, os.getpid()) self.pidfile = "%s/gpsfake-%d.pid" % (self.tmpdir, os.getpid()) def spawn(self, options, port, background=False, prefix=""): "Spawn a daemon instance." self.spawncmd = None # Look for gpsd in GPSD_HOME env variable if os.environ.get('GPSD_HOME'): for path in os.environ['GPSD_HOME'].split(':'): _spawncmd = "%s/gpsd" % path if os.path.isfile(_spawncmd) and os.access(_spawncmd, os.X_OK): self.spawncmd = _spawncmd break # if we could not find it yet try PATH env variable for it if not self.spawncmd: if not '/usr/sbin' in os.environ['PATH']: os.environ['PATH']=os.environ['PATH'] + ":/usr/sbin" for path in os.environ['PATH'].split(':'): _spawncmd = "%s/gpsd" % path if os.path.isfile(_spawncmd) and os.access(_spawncmd, os.X_OK): self.spawncmd = _spawncmd break if not self.spawncmd: raise DaemonError("Cannot execute gpsd: executable not found. Set GPSD_HOME env variable") # The -b option to suppress hanging on probe returns is needed to cope # with OpenBSD (and possibly other non-Linux systems) that don't support # anything we can use to implement the FakeGPS.read() method self.spawncmd += " -b -N -S %s -F %s -P %s %s" % (port, self.control_socket, self.pidfile, options) if prefix: self.spawncmd = prefix + " " + self.spawncmd.strip() if background: self.spawncmd += " &" status = os.system(self.spawncmd) if os.WIFSIGNALED(status) or os.WEXITSTATUS(status): raise DaemonError("daemon exited with status %d" % status) def wait_pid(self): "Wait for the daemon, get its PID and a control-socket connection." while True: try: fp = open(self.pidfile) except IOError: time.sleep(0.1) continue try: fp.seek(0) pidstr = fp.read() self.pid = int(pidstr) except ValueError: time.sleep(0.5) continue # Avoid race condition -- PID not yet written fp.close() break def __get_control_socket(self): # Now we know it's running, get a connection to the control socket. if not os.path.exists(self.control_socket): return None try: self.sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM, 0) self.sock.connect(self.control_socket) except socket.error: if self.sock: self.sock.close() self.sock = None return self.sock def is_alive(self): "Is the daemon still alive?" try: os.kill(self.pid, 0) return True except OSError: return False def add_device(self, path): "Add a device to the daemon's internal search list." if self.__get_control_socket(): self.sock.sendall("+%s\r\n\x00" % path) self.sock.recv(12) self.sock.close() def remove_device(self, path): "Remove a device from the daemon's internal search list." if self.__get_control_socket(): self.sock.sendall("-%s\r\n\x00" % path) self.sock.recv(12) self.sock.close() def kill(self): "Kill the daemon instance." if self.pid: try: os.kill(self.pid, signal.SIGTERM) # Raises an OSError for ESRCH when we've killed it. while True: os.kill(self.pid, signal.SIGTERM) time.sleep(0.01) except OSError: pass self.pid = None class TestSessionError(exceptions.Exception): def __init__(self, msg): exceptions.Exception.__init__(self) self.msg = msg class TestSession: "Manage a session including a daemon with fake GPSes and clients." def __init__(self, prefix=None, port=None, options=None, verbose=0, predump=False, udp=False, tcp=False, slow=False): "Initialize the test session by launching the daemon." self.prefix = prefix self.port = port self.options = options self.verbose = verbose self.predump = predump self.udp = udp self.tcp = tcp self.slow = slow self.daemon = DaemonInstance() self.fakegpslist = {} self.client_id = 0 self.readers = 0 self.writers = 0 self.runqueue = [] self.index = 0 self.baseport = 49194 # In the IANA orivate port range if port: self.port = port else: self.port = gps.GPSD_PORT self.close_delay = CLOSE_DELAY if slow: self.close_delay += CLOSE_DELAY_SLOWDOWN self.progress = lambda x: None self.reporter = lambda x: None self.default_predicate = None self.fd_set = [] self.threadlock = None def spawn(self): for sig in (signal.SIGQUIT, signal.SIGINT, signal.SIGTERM): signal.signal(sig, lambda unused, dummy: self.cleanup()) self.daemon.spawn(background=True, prefix=self.prefix, port=self.port, options=self.options) self.daemon.wait_pid() def set_predicate(self, pred): "Set a default go predicate for the session." self.default_predicate = pred def gps_add(self, logfile, speed=19200, pred=None): "Add a simulated GPS being fed by the specified logfile." self.progress("gpsfake: gps_add(%s, %d)\n" % (logfile, speed)) if logfile not in self.fakegpslist: testload = TestLoad(logfile, predump=self.predump, slow=self.slow) if testload.sourcetype == "UDP" or self.udp: newgps = FakeUDP(testload, ipaddr="127.0.0.1", port=self.baseport, progress=self.progress) self.baseport += 1 elif testload.sourcetype == "TCP" or self.tcp: newgps = FakeTCP(testload, host="127.0.0.1", port=self.baseport, progress=self.progress) self.baseport += 1 else: newgps = FakePTY(testload, speed=speed, progress=self.progress) if pred: newgps.go_predicate = pred elif self.default_predicate: newgps.go_predicate = self.default_predicate self.fakegpslist[newgps.byname] = newgps self.append(newgps) newgps.exhausted = 0 self.daemon.add_device(newgps.byname) return newgps.byname def gps_remove(self, name): "Remove a simulated GPS from the daemon's search list." self.progress("gpsfake: gps_remove(%s)\n" % name) self.fakegpslist[name].drain() self.remove(self.fakegpslist[name]) self.daemon.remove_device(name) del self.fakegpslist[name] def client_add(self, commands): "Initiate a client session and force connection to a fake GPS." self.progress("gpsfake: client_add()\n") newclient = gps.gps(port=self.port, verbose=self.verbose) self.append(newclient) newclient.id = self.client_id + 1 self.client_id += 1 self.progress("gpsfake: client %d has %s\n" % (self.client_id,newclient.device)) if commands: self.initialize(newclient, commands) return self.client_id def client_remove(self, cid): "Terminate a client session." self.progress("gpsfake: client_remove(%d)\n" % cid) for obj in self.runqueue: if isinstance(obj, gps.gps) and obj.id == cid: self.remove(obj) return True return False def wait(self, seconds): "Wait, doing nothing." self.progress("gpsfake: wait(%d)\n" % seconds) time.sleep(seconds) def gather(self, seconds): "Wait, doing nothing but watching for sentences." self.progress("gpsfake: gather(%d)\n" % seconds) #mark = time.time() time.sleep(seconds) def cleanup(self): "We're done, kill the daemon." self.progress("gpsfake: cleanup()\n") if self.daemon: self.daemon.kill() self.daemon = None def run(self): "Run the tests." try: self.progress("gpsfake: test loop begins\n") while self.daemon: # We have to read anything that gpsd might have tried # to send to the GPS here -- under OpenBSD the # TIOCDRAIN will hang, otherwise. for device in self.runqueue: if isinstance(device, FakeGPS): device.read() had_output = False chosen = self.choose() if isinstance(chosen, FakeGPS): if chosen.exhausted and (time.time() - chosen.exhausted > self.close_delay) and chosen.byname in self.fakegpslist: self.gps_remove(chosen.byname) self.progress("gpsfake: GPS %s removed (timeout)\n" % chosen.byname) elif not chosen.go_predicate(chosen.index, chosen): if chosen.exhausted == 0: chosen.exhausted = time.time() self.progress("gpsfake: GPS %s ran out of input\n" % chosen.byname) chosen.write("# EOF\n") else: chosen.feed() elif isinstance(chosen, gps.gps): if chosen.enqueued: chosen.send(chosen.enqueued) chosen.enqueued = "" while chosen.waiting(): chosen.read() if chosen.valid & gps.PACKET_SET: self.reporter(chosen.response) # If we're lucky, this close notification reaches # us before the device timeout. It would be nice # if this were the only logic for device closing # and we could get rid of CLOSE_DELAY, but this # sometimes fails on binary logfiles. if chosen.data["class"] == "DEVICE" and chosen.data["activated"] == 0 and chosen.data["path"] in self.fakegpslist: self.gps_remove(chosen.data["path"]) self.progress("gpsfake: GPS %s removed (notification)\n" % chosen.data["path"]) had_output = True else: raise TestSessionError("test object of unknown type") if not self.writers and not had_output: self.progress("gpsfake: no writers and no output\n") break self.progress("gpsfake: test loop ends\n") finally: self.cleanup() # All knowledge about locks and threading is below this line, # except for the bare fact that self.threadlock is set to None # in the class init method. def append(self, obj): "Add a producer or consumer to the object list." if self.threadlock: self.threadlock.acquire() self.runqueue.append(obj) if isinstance(obj, FakeGPS): self.writers += 1 elif isinstance(obj, gps.gps): self.readers += 1 if self.threadlock: self.threadlock.release() def remove(self, obj): "Remove a producer or consumer from the object list." if self.threadlock: self.threadlock.acquire() self.runqueue.remove(obj) if isinstance(obj, FakeGPS): self.writers -= 1 elif isinstance(obj, gps.gps): self.readers -= 1 self.index = min(len(self.runqueue)-1, self.index) if self.threadlock: self.threadlock.release() def choose(self): "Atomically get the next object scheduled to do something." if self.threadlock: self.threadlock.acquire() chosen = self.index self.index += 1 self.index %= len(self.runqueue) if self.threadlock: self.threadlock.release() return self.runqueue[chosen] def initialize(self, client, commands): "Arrange for client to ship specified commands when it goes active." client.enqueued = "" if not self.threadlock: client.send(commands) else: client.enqueued = commands def start(self): self.threadlock = threading.Lock() threading.Thread(target=self.run) # End