vppstats.py

"""
VPPStats is a shared memory implementation that exposes the VPP statseg as
an associative array. Counters can be accessed in either dimension.
stat['/if/rx'] - returns 2D lists
stat['/if/rx'][0] - returns counters for all interfaces for thread 0
stat['/if/rx'][0][1] - returns counter for interface 1 on thread 0
stat['/if/rx'][0][1]['packets'] - returns the packet counter
                                  for interface 1 on thread 0
stat['/if/rx'][:, 1] - returns the counters for interface 1 on all threads
stat['/if/rx'][:, 1].packets() - returns the packet counters for
                                 interface 1 on all threads
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

Usage:
    stat = VPPStats()
    stat.connect()
    for x in range(10):
        print('version ', stat.version)
        print('epoch ', stat.epoch)
        print('/if/names', stat['/if/names'])
        print('/if/rx[1].packets', stat['/if/rx'][:, 1].sum_packets())
        print('/if/rx[1].octets', stat['/if/rx'][:, 1].sum_octets())
        print('/if/tx[1].packets', stat['/if/tx'][:, 1].sum_packets())
        print('/if/tx[1].octets', stat['/if/tx'][:, 1].sum_octets())
        print("")
        time.sleep(10)

    stat.disconnect()

"""

import os
import socket
import array
import mmap
from struct import Struct
import time
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))
    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)])
    return list(fds)[0]


VEC_LEN_FMT = Struct("I")


def get_vec_len(stats, vector_offset):
    """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"""
    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")


class StatsVector:
    """A class representing a VPP vector"""

    def __init__(self, stats, ptr, fmt):
        self.vec_start = ptr - stats.base
        self.vec_len = get_vec_len(stats, ptr - stats.base)
        self.struct = Struct(fmt)
        self.fmtlen = len(fmt)
        self.elementsize = self.struct.size
        self.statseg = stats.statseg
        self.stats = stats

        if self.vec_start + self.vec_len * self.elementsize >= stats.size:
            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
                ]
            )

    def __getitem__(self, index):
        if index > self.vec_len:
            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)
            )


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"

    def __init__(self, socketname=default_socketname, timeout=10):
        self.socketname = socketname
        self.timeout = timeout
        self.directory = {}
        self.lock = StatsLock(self)
        self.connected = False
        self.size = 0
        self.last_epoch = 0
        self.statseg = 0

    def connect(self):
        """Connect to stats segment"""
        if self.connected:
            return
        sock = socket.socket(socket.AF_UNIX, socket.SOCK_SEQPACKET)
        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
        )
        os.close(mfd)

        self.size = stat_result.st_size
        if self.version != 2:
            raise Exception("Incompatbile stat segment version {}".format(self.version))

        self.refresh()
        self.connected = True

    def disconnect(self):
        """Disconnect from stats segment"""
        if self.connected:
            self.statseg.close()
            self.connected = False

    @property
    def version(self):
        """Get version of stats segment"""
        return self.shared_headerfmt.unpack_from(self.statseg)[0]

    @property
    def base(self):
        """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"""
        return self.shared_headerfmt.unpack_from(self.statseg)[2]

    @property
    def in_progress(self):
        """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"""
        return self.shared_headerfmt.unpack_from(self.statseg)[4]

    elementfmt = "IQ128s"

    def refresh(self, blocking=True):
        """Refresh directory vector cache (epoch changed)"""
        directory = {}
        directory_by_idx = {}
        while True:
            try:
                with self.lock:
                    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.directory = directory
                    self.directory_by_idx = directory_by_idx
                    return
            except IOError:
                if not blocking:
                    raise

    def __getitem__(self, item, blocking=True):
        if not self.connected:
            self.connect()
        while True:
            try:
                if self.last_epoch != self.epoch:
                    self.refresh(blocking)
                with self.lock:
                    return self.directory[item].get_counter(self)
            except IOError:
                if not blocking:
                    raise

    def __iter__(self):
        return iter(self.directory.items())

    def set_errors(self, blocking=True):
        """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/")}
        result = {}
        for k in errors:
            try:
                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:"]
        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)

    def get_counter(self, name, blocking=True):
        """Alternative call to __getitem__"""
        return self.__getitem__(name, blocking)

    def get_err_counter(self, name, blocking=True):
        """Alternative call to __getitem__"""
        return self.__getitem__(name, blocking).sum()

    def ls(self, patterns):
        """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]
        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"""
        if not self.connected:
            self.connect()
        result = {}
        for cnt in counters:
            result[cnt] = self.__getitem__(cnt, blocking)
        return result


class StatsLock:
    """Stat segment optimistic locking"""

    def __init__(self, stats):
        self.stats = stats
        self.epoch = 0

    def __enter__(self):
        acquired = self.acquire(blocking=True)
        assert acquired, "Lock wasn't acquired, but blocking=True"
        return self

    def __exit__(self, exc_type=None, exc_value=None, traceback=None):
        self.release()

    def acquire(self, blocking=True, timeout=-1):
        """Acquire the lock. Await in progress to go false. Record epoch."""
        self.epoch = self.stats.epoch
        if timeout > 0:
            start = time.monotonic()
        while self.stats.in_progress:
            if not blocking:
                time.sleep(0.01)
                if timeout > 0:
                    if start + time.monotonic() > timeout:
                        return False
        return True

    def release(self):
        """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")

    def locked(self):
        """Not used"""


class StatsCombinedList(list):
    """Column slicing for Combined counters list"""

    def __getitem__(self, item):
        """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"""

    def packets(self):
        """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 [pair[1] for pair in self]

    def sum_packets(self):
        """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 sum(self.octets())


class StatsTuple(tuple):
    """A Combined vector tuple (packets, octets)"""

    def __init__(self, data):
        self.dictionary = {"packets": data[0], "bytes": data[1]}
        super().__init__()

    def __repr__(self):
        return dict.__repr__(self.dictionary)

    def __getitem__(self, item):
        if isinstance(item, int):
            return tuple.__getitem__(self, item)
        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"""

    def __getitem__(self, item):
        """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"""

    def sum(self):
        """Sum the vector"""
        return sum(self)


class StatsEntry:
    """An individual stats entry"""

    # pylint: disable=unused-argument,no-self-use

    def __init__(self, stattype, statvalue):
        self.type = stattype
        self.value = statvalue

        if stattype == 1:
            self.function = self.scalar
        elif stattype == 2:
            self.function = self.simple
        elif stattype == 3:
            self.function = self.combined
        elif stattype == 4:
            self.function = self.name
        elif stattype == 6:
            self.function = self.symlink
        else:
            self.function = self.illegal

    def illegal(self, stats):
        """Invalid or unknown counter type"""
        return None

    def scalar(self, stats):
        """Scalar counter"""
        return self.value

    def simple(self, stats):
        """Simple counter"""
        counter = StatsSimpleList()
        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"""
        counter = StatsCombinedList()
        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 name(self, stats):
        """Name counter"""
        counter = []
        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")

    def symlink(self, stats):
        """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]

    def get_counter(self, stats):
        """Return a list of counters"""
        if stats:
            return self.function(stats)