gpsprof

gpsd, a popular GPS daemon.

#!/usr/bin/env python
#
# Collect and plot latency-profiling data from a running gpsd.
# Requires gnuplot.
#
import sys, os, time, getopt, tempfile, time, socket, math, copy
import gps

class Baton:
    "Ship progress indication to stderr."
    def __init__(self, prompt, endmsg=None):
        self.stream = sys.stderr
        self.stream.write(prompt + "...")
        if os.isatty(self.stream.fileno()):
            self.stream.write(" \010")
        self.stream.flush()
        self.count = 0
        self.endmsg = endmsg
        self.time = time.time()
        return

    def twirl(self, ch=None):
        if self.stream is None:
            return
        if ch:
            self.stream.write(ch)
        elif os.isatty(self.stream.fileno()):
            self.stream.write("-/|\\"[self.count % 4])
            self.stream.write("\010")
        self.count = self.count + 1
        self.stream.flush()
        return

    def end(self, msg=None):
        if msg == None:
            msg = self.endmsg
        if self.stream:
            self.stream.write("...(%2.2f sec) %s.\n" % (time.time() - self.time, msg))
        return

class spaceplot:
    "Total times without instrumentation."
    name = "space"
    def __init__(self):
        self.fixes = []
    def d(self, a, b):
        return math.sqrt((a[0] - b[0])**2 + (a[1] - b[1])**2)
    def gather(self, session):
        # Include altitude, not used here, for 3D plot experiments.
        # Watch out for the NaN value from gps.py.
        self.fixes.append((session.fix.latitude, session.fix.longitude, session.fix.altitude))
        return True
    def header(self, session):
        res = "# Position uncertainty, %s, %s, %ds cycle\n" % \
                 (title, session.gps_id, session.cycle)
        return res
    def data(self, session):
        res = ""
        for i in range(len(self.recentered)):
            (lat, lon) = self.recentered[i][:2]
            (raw1, raw2, alt) = self.fixes[i]
            res += "%f\t%f\t%f\t%f\t%f\n" % (lat, lon, raw1, raw2, alt)
        return res
    def plot(self, title, session):
        if len(self.fixes) == 0:
            sys.stderr.write("No fixes collected, can't estimate accuracy.")
            sys.exit(1)
        else:
            self.centroid = (sum(map(lambda x:x[0], self.fixes))/len(self.fixes), sum(map(lambda x:x[1], self.fixes))/len(self.fixes))
            # Sort fixes by distance from centroid
            self.fixes.sort(lambda x, y: cmp(self.d(self.centroid, x), self.d(self.centroid, y)))
            # Convert fixes to offsets from centroid in meters
            self.recentered = map(lambda fix: gps.MeterOffset(self.centroid, fix[:2]), self.fixes)
        # Compute CEP(50%)
        cep_meters = gps.EarthDistance(self.centroid[:2], self.fixes[len(self.fixes)/2][:2])
        alt_sum = 0
        alt_num = 0
        lon_max = -9999
        for i in range(len(self.recentered)):
            (lat, lon) = self.recentered[i][:2]
            (raw1, raw2, alt) = self.fixes[i]
            if not gps.isnan(alt):
                    alt_sum += alt
                    alt_num += 1
            if lon > lon_max :
                    lon_max = lon
        if alt_num == 0:
            alt_avg = gps.NaN
        else:
            alt_avg = alt_sum / alt_num
        if self.centroid[0] < 0:
            latstring = "%fS" % -self.centroid[0]
        elif self.centroid[0] == 0:
            latstring = "0"
        else:
            latstring = "%fN" % self.centroid[0]
        if self.centroid[1] < 0:
            lonstring = "%fW" % -self.centroid[1]
        elif self.centroid[1] == 0:
            lonstring = "0"
        else:
            lonstring = "%fE" % self.centroid[1]
        fmt = "set autoscale\n"
        fmt += 'set key below\n'
        fmt += 'set key title "%s"\n' % time.asctime()
        fmt += 'set size ratio -1\n'
        fmt += 'set style line 2 pt 1\n'
        fmt += 'set style line 3 pt 2\n'
        fmt += 'set xlabel "Meters east from %s"\n' % lonstring
        fmt += 'set ylabel "Meters north from %s"\n' % latstring
        fmt += 'set border 15\n'
        if not gps.isnan(alt_avg):
            fmt += 'set y2label "Meters Altitude from %f"\n' % alt_avg
            fmt += 'set ytics nomirror\n'
            fmt += 'set y2tics\n'
        fmt += 'cep=%f\n' % self.d((0,0), self.recentered[len(self.fixes)/2])
        fmt += 'set parametric\n'
        fmt += 'set trange [0:2*pi]\n'
        fmt += 'cx(t, r) = sin(t)*r\n'
        fmt += 'cy(t, r) = cos(t)*r\n'
        fmt += 'chlen = cep/20\n'
        fmt += "set arrow from -chlen,0 to chlen,0 nohead\n"
        fmt += "set arrow from 0,-chlen to 0,chlen nohead\n"
        fmt += 'plot cx(t, cep),cy(t, cep) title "CEP (50%%) = %f meters",  ' % (cep_meters)
        fmt += ' "-" using 1:2 with points ls 3 title "%d GPS fixes" ' % (len(self.fixes))
        if not gps.isnan(alt_avg):
            fmt += ', "-" using ( %f ):($5 < 100000 ? $5 - %f : 1/0) axes x1y2 with points ls 2 title " %d Altitude fixes, Average = %f" \n' % (lon_max +1, alt_avg, alt_num, alt_avg)
        else:
            fmt += "\n"
        fmt += self.header(session)
        fmt += self.data(session)
        if not gps.isnan(alt_avg):
            fmt += "e\n" + self.data(session)
        return fmt

class uninstrumented:
    "Total times without instrumentation."
    name = "uninstrumented"
    def __init__(self):
        self.stats = []
    def gather(self, session):
        if session.fix.time:
            seconds = time.time() - session.fix.time
            self.stats.append(seconds)
            return True
        else:
            return False
    def header(self, session):
        return "# Uninstrumented total latency, %s, %s, %dN%d, cycle %ds\n" % \
                 (title,
                  session.gps_id, session.baudrate,
                  session.stopbits, session.cycle)
    def data(self, session):
        res = ""
        for seconds in self.stats:
            res += "%2.6lf\n" % seconds
        return res
    def plot(self, title, session):
        fmt = '''
set autoscale
set key below
set key title "Uninstrumented total latency, %s, %s, %dN%d, cycle %ds"
plot "-" using 0:1 title "Total time" with impulses
'''
        res = fmt % (title,
                      session.gps_id, session.baudrate,
                      session.stopbits, session.cycle)
        res += self.header(session)
        return res + self.data(session)

class rawplot:
    "All measurement, no deductions."
    name = "raw"
    def __init__(self):
        self.stats = []
    def gather(self, session):
        self.stats.append(copy.copy(session.timings))
        return True
    def header(self, session):
        res = "# Raw latency data, %s, %s, %dN%d, cycle %ds\n" % \
                 (title,
                  session.gps_id, session.baudrate,
                  session.stopbits, session.cycle)
        res += "#"
        for hn in ("tag", "T1", "E1", "D1", "W", "E2", "T2", "D2"):
            res += "%8s\t" % hn
        res += "\n#"
        for i in range(0, 7):
            res += "--------\t"
        return res + "--------\n"
    def data(self, session):
        res = ""
        for timings in self.stats:
            if timings.sentence_time:
                e1 = timings.d_xmit_time
            else:
                e1 = 0
            res += "%s\t%2d\t%2.6f\t%2.6f\t%2.6f\t%2.6f\t%2.6f\t%2.6f\t%2.6f\n" \
                % (timings.sentence_tag,
                   timings.sentence_length,
                   e1, 
                   timings.d_recv_time,
                   timings.d_decode_time,
                   timings.poll_time,
                   timings.emit_time,
                   timings.c_recv_time,
                   timings.c_decode_time)
        return res
    def plot(self, file, session):
        fmt = '''
set autoscale
set key below
set key title "Raw latency data, %s, %s, %dN%d, cycle %ds"
plot \
     "-" using 0:9 title "D2 = Client decode time" with impulses, \
     "-" using 0:8 title "T2 =     TCP/IP latency" with impulses, \
     "-" using 0:7 title "E2 = Daemon encode time" with impulses, \
     "-" using 0:6 title "W  =     Poll wait time" with impulses, \
     "-" using 0:5 title "D1 = Daemon decode time" with impulses, \
     "-" using 0:4 title "T1 =         RS232 time" with impulses, \
     "-" using 0:3 title "E1 =        GPS latency" with impulses
'''
        res = fmt % (title,
                      session.gps_id, session.baudrate,
                      session.stopbits, session.cycle)
        res += self.header(session)
        for dummy in range(0, 7):
            res += self.data(session) + "e\n"
        return res

class splitplot:
    "Discard base time, use color to indicate different tags."
    name = "split"
    sentences = []