X-Git-Url: https://gerrit.fd.io/r/gitweb?a=blobdiff_plain;f=src%2Fvpp-api%2Fpython%2Fvpp_papi%2Fvpp_stats.py;h=aa9ff85b3c70e3f4b91e6d72533822633af2031a;hb=b3ee84d0bb531f0600e3c038e78680c083e5bb77;hp=884a30019f8a1631803e8cbd57387405949bf8a8;hpb=d640ae52f6d0903e8921f8b259bac3431f9cce4b;p=vpp.git

diff --git a/src/vpp-api/python/vpp_papi/vpp_stats.py b/src/vpp-api/python/vpp_papi/vpp_stats.py
index 884a30019f8..aa9ff85b3c7 100755
--- a/src/vpp-api/python/vpp_papi/vpp_stats.py
+++ b/src/vpp-api/python/vpp_papi/vpp_stats.py
@@ -14,7 +14,7 @@
 # limitations under the License.
 #
 
-'''
+"""
 This module implement Python access to the VPP statistics segment. It
 accesses the data structures directly in shared memory.
 VPP uses optimistic locking, so data structures may change underneath
@@ -39,7 +39,7 @@ stat['/if/rx'][:, 1].sum_packets() - returns the sum of packet counters for
                                      interface 1 on all threads
 stat['/if/rx-miss'][:, 1].sum() - returns the sum of packet counters for
                                   interface 1 on all threads for simple counters
-'''
+"""
 
 import os
 import socket
@@ -50,31 +50,36 @@ import time
 import unittest
 import re
 
+
 def recv_fd(sock):
-    '''Get file descriptor for memory map'''
-    fds = array.array("i")   # Array of ints
-    _, ancdata, _, _ = sock.recvmsg(0, socket.CMSG_LEN(4))
+    """Get file descriptor for memory map"""
+    fds = array.array("i")  # Array of ints
+    _, ancdata, _, _ = sock.recvmsg(0, socket.CMSG_SPACE(4))
     for cmsg_level, cmsg_type, cmsg_data in ancdata:
         if cmsg_level == socket.SOL_SOCKET and cmsg_type == socket.SCM_RIGHTS:
-            fds.frombytes(cmsg_data[:len(cmsg_data) - (len(cmsg_data) % fds.itemsize)])
+            fds.frombytes(cmsg_data[: len(cmsg_data) - (len(cmsg_data) % fds.itemsize)])
     return list(fds)[0]
 
-VEC_LEN_FMT = Struct('I')
+
+VEC_LEN_FMT = Struct("I")
+
+
 def get_vec_len(stats, vector_offset):
-    '''Equivalent to VPP vec_len()'''
+    """Equivalent to VPP vec_len()"""
     return VEC_LEN_FMT.unpack_from(stats.statseg, vector_offset - 8)[0]
 
+
 def get_string(stats, ptr):
-    '''Get a string from a VPP vector'''
+    """Get a string from a VPP vector"""
     namevector = ptr - stats.base
     namevectorlen = get_vec_len(stats, namevector)
     if namevector + namevectorlen >= stats.size:
-        raise IOError('String overruns stats segment')
-    return stats.statseg[namevector:namevector+namevectorlen-1].decode('ascii')
+        raise IOError("String overruns stats segment")
+    return stats.statseg[namevector : namevector + namevectorlen - 1].decode("ascii")
 
 
 class StatsVector:
-    '''A class representing a VPP vector'''
+    """A class representing a VPP vector"""
 
     def __init__(self, stats, ptr, fmt):
         self.vec_start = ptr - stats.base
@@ -86,28 +91,35 @@ class StatsVector:
         self.stats = stats
 
         if self.vec_start + self.vec_len * self.elementsize >= stats.size:
-            raise IOError('Vector overruns stats segment')
+            raise IOError("Vector overruns stats segment")
 
     def __iter__(self):
         with self.stats.lock:
-            return self.struct.iter_unpack(self.statseg[self.vec_start:self.vec_start +
-                                                        self.elementsize*self.vec_len])
+            return self.struct.iter_unpack(
+                self.statseg[
+                    self.vec_start : self.vec_start + self.elementsize * self.vec_len
+                ]
+            )
 
     def __getitem__(self, index):
         if index > self.vec_len:
-            raise IOError('Index beyond end of vector')
+            raise IOError("Index beyond end of vector")
         with self.stats.lock:
             if self.fmtlen == 1:
-                return self.struct.unpack_from(self.statseg, self.vec_start +
-                                               (index * self.elementsize))[0]
-            return self.struct.unpack_from(self.statseg, self.vec_start +
-                                           (index * self.elementsize))
+                return self.struct.unpack_from(
+                    self.statseg, self.vec_start + (index * self.elementsize)
+                )[0]
+            return self.struct.unpack_from(
+                self.statseg, self.vec_start + (index * self.elementsize)
+            )
+
+
+class VPPStats:
+    """Main class implementing Python access to the VPP statistics segment"""
 
-class VPPStats():
-    '''Main class implementing Python access to the VPP statistics segment'''
     # pylint: disable=too-many-instance-attributes
-    shared_headerfmt = Struct('QPQQPP')
-    default_socketname = '/run/vpp/stats.sock'
+    shared_headerfmt = Struct("QPQQPP")
+    default_socketname = "/run/vpp/stats.sock"
 
     def __init__(self, socketname=default_socketname, timeout=10):
         self.socketname = socketname
@@ -117,89 +129,87 @@ class VPPStats():
         self.connected = False
         self.size = 0
         self.last_epoch = 0
-        self.error_vectors = 0
         self.statseg = 0
 
     def connect(self):
-        '''Connect to stats segment'''
+        """Connect to stats segment"""
         if self.connected:
             return
         sock = socket.socket(socket.AF_UNIX, socket.SOCK_SEQPACKET)
+
+        # Our connect races the corresponding recv_fds call in VPP, if we beat
+        # VPP then we will try (unsuccessfully) to receive file descriptors and
+        # will have gone away before VPP can respond to our connect.  A short
+        # timeout here stops this error occurring.
+        sock.settimeout(1)
         sock.connect(self.socketname)
 
         mfd = recv_fd(sock)
         sock.close()
 
         stat_result = os.fstat(mfd)
-        self.statseg = mmap.mmap(mfd, stat_result.st_size, mmap.PROT_READ, mmap.MAP_SHARED)
+        self.statseg = mmap.mmap(
+            mfd, stat_result.st_size, mmap.PROT_READ, mmap.MAP_SHARED
+        )
         os.close(mfd)
 
         self.size = stat_result.st_size
         if self.version != 2:
-            raise Exception('Incompatbile stat segment version {}'
-                            .format(self.version))
+            raise Exception("Incompatbile stat segment version {}".format(self.version))
 
         self.refresh()
         self.connected = True
 
     def disconnect(self):
-        '''Disconnect from stats segment'''
+        """Disconnect from stats segment"""
         if self.connected:
             self.statseg.close()
             self.connected = False
 
     @property
     def version(self):
-        '''Get version of stats segment'''
+        """Get version of stats segment"""
         return self.shared_headerfmt.unpack_from(self.statseg)[0]
 
     @property
     def base(self):
-        '''Get base pointer of stats segment'''
+        """Get base pointer of stats segment"""
         return self.shared_headerfmt.unpack_from(self.statseg)[1]
 
     @property
     def epoch(self):
-        '''Get current epoch value from stats segment'''
+        """Get current epoch value from stats segment"""
         return self.shared_headerfmt.unpack_from(self.statseg)[2]
 
     @property
     def in_progress(self):
-        '''Get value of in_progress from stats segment'''
+        """Get value of in_progress from stats segment"""
         return self.shared_headerfmt.unpack_from(self.statseg)[3]
 
     @property
     def directory_vector(self):
-        '''Get pointer of directory vector'''
+        """Get pointer of directory vector"""
         return self.shared_headerfmt.unpack_from(self.statseg)[4]
 
-    @property
-    def error_vector(self):
-        '''Get pointer of error vector'''
-        return self.shared_headerfmt.unpack_from(self.statseg)[5]
-
-    elementfmt = 'IQ128s'
+    elementfmt = "IQ128s"
 
     def refresh(self, blocking=True):
-        '''Refresh directory vector cache (epoch changed)'''
+        """Refresh directory vector cache (epoch changed)"""
         directory = {}
         directory_by_idx = {}
         while True:
             try:
                 with self.lock:
-                    for i, direntry in enumerate(StatsVector(self, self.directory_vector, self.elementfmt)):
-                        path_raw = direntry[2].find(b'\x00')
-                        path = direntry[2][:path_raw].decode('ascii')
+                    self.last_epoch = self.epoch
+                    for i, direntry in enumerate(
+                        StatsVector(self, self.directory_vector, self.elementfmt)
+                    ):
+                        path_raw = direntry[2].find(b"\x00")
+                        path = direntry[2][:path_raw].decode("ascii")
                         directory[path] = StatsEntry(direntry[0], direntry[1])
                         directory_by_idx[i] = path
-                    self.last_epoch = self.epoch
                     self.directory = directory
                     self.directory_by_idx = directory_by_idx
-
-                    # Cache the error index vectors
-                    self.error_vectors = []
-                    for threads in StatsVector(self, self.error_vector, 'P'):
-                        self.error_vectors.append(StatsVector(self, threads[0], 'Q'))
                     return
             except IOError:
                 if not blocking:
@@ -222,78 +232,66 @@ class VPPStats():
         return iter(self.directory.items())
 
     def set_errors(self, blocking=True):
-        '''Return dictionary of error counters > 0'''
+        """Return dictionary of error counters > 0"""
         if not self.connected:
             self.connect()
 
-        errors = {k:v for k, v in self.directory.items() if k.startswith("/err/")}
+        errors = {k: v for k, v in self.directory.items() if k.startswith("/err/")}
         result = {}
-        while True:
+        for k in errors:
             try:
-                if self.last_epoch != self.epoch:
-                    self.refresh(blocking)
-                with self.lock:
-                    for k, entry in errors.items():
-                        total = 0
-                        i = entry.value
-                        for per_thread in self.error_vectors:
-                            total += per_thread[i]
-                        if total:
-                            result[k] = total
-                return result
-            except IOError:
-                if not blocking:
-                    raise
+                total = self[k].sum()
+                if total:
+                    result[k] = total
+            except KeyError:
+                pass
+        return result
 
     def set_errors_str(self, blocking=True):
-        '''Return all errors counters > 0 pretty printed'''
-        error_string = ['ERRORS:']
+        """Return all errors counters > 0 pretty printed"""
+        error_string = ["ERRORS:"]
         error_counters = self.set_errors(blocking)
         for k in sorted(error_counters):
-            error_string.append('{:<60}{:>10}'.format(k, error_counters[k]))
-        return '%s\n' % '\n'.join(error_string)
+            error_string.append("{:<60}{:>10}".format(k, error_counters[k]))
+        return "%s\n" % "\n".join(error_string)
 
     def get_counter(self, name, blocking=True):
-        '''Alternative call to __getitem__'''
+        """Alternative call to __getitem__"""
         return self.__getitem__(name, blocking)
 
     def get_err_counter(self, name, blocking=True):
-        '''Return a single value (sum of all threads)'''
-        if not self.connected:
-            self.connect()
-        if name.startswith("/err/"):
-            while True:
-                try:
-                    if self.last_epoch != self.epoch:
-                        self.refresh(blocking)
-                    with self.lock:
-                        return sum(self.directory[name].get_counter(self))
-                except IOError:
-                    if not blocking:
-                        raise
+        """Alternative call to __getitem__"""
+        return self.__getitem__(name, blocking).sum()
 
     def ls(self, patterns):
-        '''Returns list of counters matching pattern'''
+        """Returns list of counters matching pattern"""
         # pylint: disable=invalid-name
         if not self.connected:
             self.connect()
         if not isinstance(patterns, list):
             patterns = [patterns]
         regex = [re.compile(i) for i in patterns]
-        return [k for k, v in self.directory.items()
-                if any(re.match(pattern, k) for pattern in regex)]
+        if self.last_epoch != self.epoch:
+            self.refresh()
+
+        return [
+            k
+            for k, v in self.directory.items()
+            if any(re.match(pattern, k) for pattern in regex)
+        ]
 
     def dump(self, counters, blocking=True):
-        '''Given a list of counters return a dictionary of results'''
+        """Given a list of counters return a dictionary of results"""
         if not self.connected:
             self.connect()
         result = {}
         for cnt in counters:
-            result[cnt] = self.__getitem__(cnt,blocking)
+            result[cnt] = self.__getitem__(cnt, blocking)
         return result
 
-class StatsLock():
-    '''Stat segment optimistic locking'''
+
+class StatsLock:
+    """Stat segment optimistic locking"""
 
     def __init__(self, stats):
         self.stats = stats
@@ -308,7 +306,7 @@ class StatsLock():
         self.release()
 
     def acquire(self, blocking=True, timeout=-1):
-        '''Acquire the lock. Await in progress to go false. Record epoch.'''
+        """Acquire the lock. Await in progress to go false. Record epoch."""
         self.epoch = self.stats.epoch
         if timeout > 0:
             start = time.monotonic()
@@ -321,46 +319,49 @@ class StatsLock():
         return True
 
     def release(self):
-        '''Check if data read while locked is valid'''
+        """Check if data read while locked is valid"""
         if self.stats.in_progress or self.stats.epoch != self.epoch:
-            raise IOError('Optimistic lock failed, retry')
+            raise IOError("Optimistic lock failed, retry")
 
     def locked(self):
-        '''Not used'''
+        """Not used"""
 
 
 class StatsCombinedList(list):
-    '''Column slicing for Combined counters list'''
+    """Column slicing for Combined counters list"""
 
     def __getitem__(self, item):
-        '''Supports partial numpy style 2d support. Slice by column [:,1]'''
+        """Supports partial numpy style 2d support. Slice by column [:,1]"""
         if isinstance(item, int):
             return list.__getitem__(self, item)
         return CombinedList([row[item[1]] for row in self])
 
+
 class CombinedList(list):
-    '''Combined Counters 2-dimensional by thread by index of packets/octets'''
+    """Combined Counters 2-dimensional by thread by index of packets/octets"""
 
     def packets(self):
-        '''Return column (2nd dimension). Packets for all threads'''
+        """Return column (2nd dimension). Packets for all threads"""
         return [pair[0] for pair in self]
 
     def octets(self):
-        '''Return column (2nd dimension). Octets for all threads'''
+        """Return column (2nd dimension). Octets for all threads"""
         return [pair[1] for pair in self]
 
     def sum_packets(self):
-        '''Return column (2nd dimension). Sum of all packets for all threads'''
+        """Return column (2nd dimension). Sum of all packets for all threads"""
         return sum(self.packets())
 
     def sum_octets(self):
-        '''Return column (2nd dimension). Sum of all octets for all threads'''
+        """Return column (2nd dimension). Sum of all octets for all threads"""
         return sum(self.octets())
 
+
 class StatsTuple(tuple):
-    '''A Combined vector tuple (packets, octets)'''
+    """A Combined vector tuple (packets, octets)"""
+
     def __init__(self, data):
-        self.dictionary = {'packets': data[0], 'bytes': data[1]}
+        self.dictionary = {"packets": data[0], "bytes": data[1]}
         super().__init__()
 
     def __repr__(self):
@@ -369,28 +370,32 @@ class StatsTuple(tuple):
     def __getitem__(self, item):
         if isinstance(item, int):
             return tuple.__getitem__(self, item)
-        if item == 'packets':
+        if item == "packets":
             return tuple.__getitem__(self, 0)
         return tuple.__getitem__(self, 1)
 
+
 class StatsSimpleList(list):
-    '''Simple Counters 2-dimensional by thread by index of packets'''
+    """Simple Counters 2-dimensional by thread by index of packets"""
 
     def __getitem__(self, item):
-        '''Supports partial numpy style 2d support. Slice by column [:,1]'''
+        """Supports partial numpy style 2d support. Slice by column [:,1]"""
         if isinstance(item, int):
             return list.__getitem__(self, item)
         return SimpleList([row[item[1]] for row in self])
 
+
 class SimpleList(list):
-    '''Simple counter'''
+    """Simple counter"""
 
     def sum(self):
-        '''Sum the vector'''
+        """Sum the vector"""
         return sum(self)
 
-class StatsEntry():
-    '''An individual stats entry'''
+
+class StatsEntry:
+    """An individual stats entry"""
+
     # pylint: disable=unused-argument,no-self-use
 
     def __init__(self, stattype, statvalue):
@@ -404,140 +409,135 @@ class StatsEntry():
         elif stattype == 3:
             self.function = self.combined
         elif stattype == 4:
-            self.function = self.error
-        elif stattype == 5:
             self.function = self.name
-        elif stattype == 7:
+        elif stattype == 6:
             self.function = self.symlink
         else:
             self.function = self.illegal
 
     def illegal(self, stats):
-        '''Invalid or unknown counter type'''
+        """Invalid or unknown counter type"""
         return None
 
     def scalar(self, stats):
-        '''Scalar counter'''
+        """Scalar counter"""
         return self.value
 
     def simple(self, stats):
-        '''Simple counter'''
+        """Simple counter"""
         counter = StatsSimpleList()
-        for threads in StatsVector(stats, self.value, 'P'):
-            clist = [v[0] for v in StatsVector(stats, threads[0], 'Q')]
+        for threads in StatsVector(stats, self.value, "P"):
+            clist = [v[0] for v in StatsVector(stats, threads[0], "Q")]
             counter.append(clist)
         return counter
 
     def combined(self, stats):
-        '''Combined counter'''
+        """Combined counter"""
         counter = StatsCombinedList()
-        for threads in StatsVector(stats, self.value, 'P'):
-            clist = [StatsTuple(cnt) for cnt in StatsVector(stats, threads[0], 'QQ')]
+        for threads in StatsVector(stats, self.value, "P"):
+            clist = [StatsTuple(cnt) for cnt in StatsVector(stats, threads[0], "QQ")]
             counter.append(clist)
         return counter
 
-    def error(self, stats):
-        '''Error counter'''
-        counter = SimpleList()
-        for clist in stats.error_vectors:
-            counter.append(clist[self.value])
-        return counter
-
     def name(self, stats):
-        '''Name counter'''
+        """Name counter"""
         counter = []
-        for name in StatsVector(stats, self.value, 'P'):
+        for name in StatsVector(stats, self.value, "P"):
             if name[0]:
                 counter.append(get_string(stats, name[0]))
         return counter
 
-    SYMLINK_FMT1 = Struct('II')
-    SYMLINK_FMT2 = Struct('Q')
+    SYMLINK_FMT1 = Struct("II")
+    SYMLINK_FMT2 = Struct("Q")
+
     def symlink(self, stats):
-        '''Symlink counter'''
+        """Symlink counter"""
         b = self.SYMLINK_FMT2.pack(self.value)
         index1, index2 = self.SYMLINK_FMT1.unpack(b)
         name = stats.directory_by_idx[index1]
-        return stats[name][:,index2]
+        return stats[name][:, index2]
 
     def get_counter(self, stats):
-        '''Return a list of counters'''
+        """Return a list of counters"""
         if stats:
             return self.function(stats)
 
+
 class TestStats(unittest.TestCase):
-    '''Basic statseg tests'''
+    """Basic statseg tests"""
 
     def setUp(self):
-        '''Connect to statseg'''
+        """Connect to statseg"""
         self.stat = VPPStats()
         self.stat.connect()
         self.profile = cProfile.Profile()
         self.profile.enable()
 
     def tearDown(self):
-        '''Disconnect from statseg'''
+        """Disconnect from statseg"""
         self.stat.disconnect()
         profile = Stats(self.profile)
         profile.strip_dirs()
-        profile.sort_stats('cumtime')
+        profile.sort_stats("cumtime")
         profile.print_stats()
         print("\n--->>>")
 
     def test_counters(self):
-        '''Test access to statseg'''
-
-        print('/err/abf-input-ip4/missed', self.stat['/err/abf-input-ip4/missed'])
-        print('/sys/heartbeat', self.stat['/sys/heartbeat'])
-        print('/if/names', self.stat['/if/names'])
-        print('/if/rx-miss', self.stat['/if/rx-miss'])
-        print('/if/rx-miss', self.stat['/if/rx-miss'][1])
-        print('/nat44-ed/out2in/slowpath/drops', self.stat['/nat44-ed/out2in/slowpath/drops'])
-        print('Set Errors', self.stat.set_errors())
+        """Test access to statseg"""
+
+        print("/err/abf-input-ip4/missed", self.stat["/err/abf-input-ip4/missed"])
+        print("/sys/heartbeat", self.stat["/sys/heartbeat"])
+        print("/if/names", self.stat["/if/names"])
+        print("/if/rx-miss", self.stat["/if/rx-miss"])
+        print("/if/rx-miss", self.stat["/if/rx-miss"][1])
+        print(
+            "/nat44-ed/out2in/slowpath/drops",
+            self.stat["/nat44-ed/out2in/slowpath/drops"],
+        )
         with self.assertRaises(KeyError):
-            print('NO SUCH COUNTER', self.stat['foobar'])
-        print('/if/rx', self.stat.get_counter('/if/rx'))
-        print('/err/ethernet-input/no error',
-              self.stat.get_err_counter('/err/ethernet-input/no error'))
+            print("NO SUCH COUNTER", self.stat["foobar"])
+        print("/if/rx", self.stat.get_counter("/if/rx"))
+        print(
+            "/err/ethernet-input/no_error",
+            self.stat.get_counter("/err/ethernet-input/no_error"),
+        )
 
     def test_column(self):
-        '''Test column slicing'''
-
-        print('/if/rx-miss', self.stat['/if/rx-miss'])
-        print('/if/rx', self.stat['/if/rx'])  # All interfaces for thread #1
-        print('/if/rx thread #1', self.stat['/if/rx'][0])  # All interfaces for thread #1
-        print('/if/rx thread #1, interface #1',
-              self.stat['/if/rx'][0][1])  # All interfaces for thread #1
-        print('/if/rx if_index #1', self.stat['/if/rx'][:, 1])
-        print('/if/rx if_index #1 packets', self.stat['/if/rx'][:, 1].packets())
-        print('/if/rx if_index #1 packets', self.stat['/if/rx'][:, 1].sum_packets())
-        print('/if/rx if_index #1 packets', self.stat['/if/rx'][:, 1].octets())
-        print('/if/rx-miss', self.stat['/if/rx-miss'])
-        print('/if/rx-miss if_index #1 packets', self.stat['/if/rx-miss'][:, 1].sum())
-        print('/if/rx if_index #1 packets', self.stat['/if/rx'][0][1]['packets'])
-
-    def test_error(self):
-        '''Test the error vector'''
-
-        print('/err/ethernet-input', self.stat['/err/ethernet-input/no error'])
-        print('/err/nat44-ei-ha/pkts-processed', self.stat['/err/nat44-ei-ha/pkts-processed'])
-        print('/err/ethernet-input', self.stat.get_err_counter('/err/ethernet-input/no error'))
-        print('/err/ethernet-input', self.stat['/err/ethernet-input/no error'].sum())
+        """Test column slicing"""
+
+        print("/if/rx-miss", self.stat["/if/rx-miss"])
+        print("/if/rx", self.stat["/if/rx"])  # All interfaces for thread #1
+        print(
+            "/if/rx thread #1", self.stat["/if/rx"][0]
+        )  # All interfaces for thread #1
+        print(
+            "/if/rx thread #1, interface #1", self.stat["/if/rx"][0][1]
+        )  # All interfaces for thread #1
+        print("/if/rx if_index #1", self.stat["/if/rx"][:, 1])
+        print("/if/rx if_index #1 packets", self.stat["/if/rx"][:, 1].packets())
+        print("/if/rx if_index #1 packets", self.stat["/if/rx"][:, 1].sum_packets())
+        print("/if/rx if_index #1 packets", self.stat["/if/rx"][:, 1].octets())
+        print("/if/rx-miss", self.stat["/if/rx-miss"])
+        print("/if/rx-miss if_index #1 packets", self.stat["/if/rx-miss"][:, 1].sum())
+        print("/if/rx if_index #1 packets", self.stat["/if/rx"][0][1]["packets"])
 
     def test_nat44(self):
-        '''Test the nat counters'''
+        """Test the nat counters"""
 
-        print('/nat44-ei/ha/del-event-recv', self.stat['/nat44-ei/ha/del-event-recv'])
-        print('/err/nat44-ei-ha/pkts-processed', self.stat['/err/nat44-ei-ha/pkts-processed'].sum())
+        print("/nat44-ei/ha/del-event-recv", self.stat["/nat44-ei/ha/del-event-recv"])
+        print(
+            "/err/nat44-ei-ha/pkts-processed",
+            self.stat["/err/nat44-ei-ha/pkts-processed"].sum(),
+        )
 
     def test_legacy(self):
-        '''Legacy interface'''
+        """Legacy interface"""
         directory = self.stat.ls(["^/if", "/err/ip4-input", "/sys/node/ip4-input"])
         data = self.stat.dump(directory)
         print(data)
-        print('Looking up sys node')
+        print("Looking up sys node")
         directory = self.stat.ls(["^/sys/node"])
-        print('Dumping sys node')
+        print("Dumping sys node")
         data = self.stat.dump(directory)
         print(data)
         directory = self.stat.ls(["^/foobar"])
@@ -545,18 +545,19 @@ class TestStats(unittest.TestCase):
         print(data)
 
     def test_sys_nodes(self):
-        '''Test /sys/nodes'''
-        counters = self.stat.ls('^/sys/node')
-        print('COUNTERS:', counters)
-        print('/sys/node', self.stat.dump(counters))
-        print('/net/route/to', self.stat['/net/route/to'])
+        """Test /sys/nodes"""
+        counters = self.stat.ls("^/sys/node")
+        print("COUNTERS:", counters)
+        print("/sys/node", self.stat.dump(counters))
+        print("/net/route/to", self.stat["/net/route/to"])
 
     def test_symlink(self):
-        '''Symbolic links'''
-        print('/interface/local0/rx', self.stat['/interfaces/local0/rx'])
-        print('/sys/nodes/unix-epoll-input', self.stat['/nodes/unix-epoll-input/calls'])
+        """Symbolic links"""
+        print("/interface/local0/rx", self.stat["/interfaces/local0/rx"])
+        print("/sys/nodes/unix-epoll-input", self.stat["/nodes/unix-epoll-input/calls"])
+
 
-if __name__ == '__main__':
+if __name__ == "__main__":
     import cProfile
     from pstats import Stats