utils.py

# Copyright 2012-2014 MongoDB, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Utilities for testing pymongo
"""

import sys
import threading

from nose.plugins.skip import SkipTest
from pymongo import MongoClient, MongoReplicaSetClient
from pymongo.errors import AutoReconnect
from pymongo.pool import NO_REQUEST, NO_SOCKET_YET, SocketInfo
from test import host, port, version


try:
    import gevent
    has_gevent = True
except ImportError:
    has_gevent = False


# No functools in Python 2.4
def my_partial(f, *args, **kwargs):
    def _f(*new_args, **new_kwargs):
        final_kwargs = kwargs.copy()
        final_kwargs.update(new_kwargs)
        return f(*(args + new_args), **final_kwargs)

    return _f

def one(s):
    """Get one element of a set"""
    return iter(s).next()

def delay(sec):
    # Javascript sleep() only available in MongoDB since version ~1.9
    return '''function() {
        var d = new Date((new Date()).getTime() + %s * 1000);
        while (d > (new Date())) { }; return true;
    }''' % sec

def get_command_line(client):
    command_line = client.admin.command('getCmdLineOpts')
    assert command_line['ok'] == 1, "getCmdLineOpts() failed"
    return command_line

def server_started_with_option(client, cmdline_opt, config_opt):
    """Check if the server was started with a particular option.
    
    :Parameters:
      - `cmdline_opt`: The command line option (i.e. --nojournal)
      - `config_opt`: The config file option (i.e. nojournal)
    """
    command_line = get_command_line(client)
    if 'parsed' in command_line:
        parsed = command_line['parsed']
        if config_opt in parsed:
            return parsed[config_opt]
    argv = command_line['argv']
    return cmdline_opt in argv


def server_started_with_auth(client):
    command_line = get_command_line(client)
    if 'parsed' in command_line:
        parsed = command_line['parsed']
        return parsed.get('auth', False) or bool(parsed.get('keyFile'))
    argv = command_line['argv']
    return '--auth' in argv or '--keyFile' in argv

def server_is_master_with_slave(client):
    command_line = get_command_line(client)
    if 'parsed' in command_line:
        return command_line['parsed'].get('master', False)
    return '--master' in command_line['argv']

def drop_collections(db):
    for coll in db.collection_names():
        if not coll.startswith('system'):
            db.drop_collection(coll)

def remove_all_users(db):
    if version.at_least(db.connection, (2, 5, 3, -1)):
        db.command({"dropAllUsersFromDatabase": 1})
    else:
        db.system.users.remove({})


def joinall(threads):
    """Join threads with a 5-minute timeout, assert joins succeeded"""
    for t in threads:
        t.join(300)
        assert not t.isAlive(), "Thread %s hung" % t

def is_mongos(client):
    res = client.admin.command('ismaster')
    return res.get('msg', '') == 'isdbgrid'

def enable_text_search(client):
    client.admin.command(
        'setParameter', textSearchEnabled=True)

    if isinstance(client, MongoReplicaSetClient):
        for host, port in client.secondaries:
            MongoClient(host, port).admin.command(
                'setParameter', textSearchEnabled=True)

def assertRaisesExactly(cls, fn, *args, **kwargs):
    """
    Unlike the standard assertRaises, this checks that a function raises a
    specific class of exception, and not a subclass. E.g., check that
    MongoClient() raises ConnectionFailure but not its subclass, AutoReconnect.
    """
    try:
        fn(*args, **kwargs)
    except Exception, e:
        assert e.__class__ == cls, "got %s, expected %s" % (
            e.__class__.__name__, cls.__name__)
    else:
        raise AssertionError("%s not raised" % cls)

def looplet(greenlets):
    """World's smallest event loop; run until all greenlets are done
    """
    while True:
        done = True

        for g in greenlets:
            if not g.dead:
                done = False
                g.switch()

        if done:
            return

class RendezvousThread(threading.Thread):
    """A thread that starts and pauses at a rendezvous point before resuming.
    To be used in tests that must ensure that N threads are all alive
    simultaneously, regardless of thread-scheduling's vagaries.

    1. Write a subclass of RendezvousThread and override before_rendezvous
      and / or after_rendezvous.
    2. Create a state with RendezvousThread.shared_state(N)
    3. Start N of your subclassed RendezvousThreads, passing the state to each
      one's __init__
    4. In the main thread, call RendezvousThread.wait_for_rendezvous
    5. Test whatever you need to test while threads are paused at rendezvous
      point
    6. In main thread, call RendezvousThread.resume_after_rendezvous
    7. Join all threads from main thread
    8. Assert that all threads' "passed" attribute is True
    9. Test post-conditions
    """
    class RendezvousState(object):
        def __init__(self, nthreads):
            # Number of threads total
            self.nthreads = nthreads
    
            # Number of threads that have arrived at rendezvous point
            self.arrived_threads = 0
            self.arrived_threads_lock = threading.Lock()
    
            # Set when all threads reach rendezvous
            self.ev_arrived = threading.Event()
    
            # Set by resume_after_rendezvous() so threads can continue.
            self.ev_resume = threading.Event()
            

    @classmethod
    def create_shared_state(cls, nthreads):
        return RendezvousThread.RendezvousState(nthreads)

    def before_rendezvous(self):
        """Overridable: Do this before the rendezvous"""
        pass

    def after_rendezvous(self):
        """Overridable: Do this after the rendezvous. If it throws no exception,
        `passed` is set to True
        """
        pass

    @classmethod
    def wait_for_rendezvous(cls, state):
        """Wait for all threads to reach rendezvous and pause there"""
        state.ev_arrived.wait(10)
        assert state.ev_arrived.isSet(), "Thread timeout"
        assert state.nthreads == state.arrived_threads

    @classmethod
    def resume_after_rendezvous(cls, state):
        """Tell all the paused threads to continue"""
        state.ev_resume.set()

    def __init__(self, state):
        """Params:
          `state`: A shared state object from RendezvousThread.shared_state()
        """
        super(RendezvousThread, self).__init__()
        self.state = state
        self.passed = False

        # If this thread fails to terminate, don't hang the whole program
        self.setDaemon(True)

    def _rendezvous(self):
        """Pause until all threads arrive here"""
        s = self.state
        s.arrived_threads_lock.acquire()
        s.arrived_threads += 1
        if s.arrived_threads == s.nthreads:
            s.arrived_threads_lock.release()
            s.ev_arrived.set()
        else:
            s.arrived_threads_lock.release()
            s.ev_arrived.wait()

    def run(self):
        try:
            self.before_rendezvous()
        finally:
            self._rendezvous()

        # all threads have passed the rendezvous, wait for
        # resume_after_rendezvous()
        self.state.ev_resume.wait()

        self.after_rendezvous()
        self.passed = True

def read_from_which_host(
    rsc,
    mode,
    tag_sets=None,
    secondary_acceptable_latency_ms=15
):
    """Read from a MongoReplicaSetClient with the given Read Preference mode,
       tags, and acceptable latency. Return the 'host:port' which was read from.

    :Parameters:
      - `rsc`: A MongoReplicaSetClient
      - `mode`: A ReadPreference
      - `tag_sets`: List of dicts of tags for data-center-aware reads
      - `secondary_acceptable_latency_ms`: a float
    """
    db = rsc.pymongo_test
    db.read_preference = mode
    if isinstance(tag_sets, dict):
        tag_sets = [tag_sets]
    db.tag_sets = tag_sets or [{}]
    db.secondary_acceptable_latency_ms = secondary_acceptable_latency_ms

    cursor = db.test.find()
    try:
        try:
            cursor.next()
        except StopIteration:
            # No documents in collection, that's fine
            pass

        return cursor._Cursor__connection_id
    except AutoReconnect:
        return None

def assertReadFrom(testcase, rsc, member, *args, **kwargs):
    """Check that a query with the given mode, tag_sets, and
       secondary_acceptable_latency_ms reads from the expected replica-set
       member

    :Parameters:
      - `testcase`: A unittest.TestCase
      - `rsc`: A MongoReplicaSetClient
      - `member`: A host:port expected to be used
      - `mode`: A ReadPreference
      - `tag_sets` (optional): List of dicts of tags for data-center-aware reads
      - `secondary_acceptable_latency_ms` (optional): a float
    """
    for _ in range(10):
        testcase.assertEqual(member, read_from_which_host(rsc, *args, **kwargs))

def assertReadFromAll(testcase, rsc, members, *args, **kwargs):
    """Check that a query with the given mode, tag_sets, and
    secondary_acceptable_latency_ms reads from all members in a set, and
    only members in that set.

    :Parameters:
      - `testcase`: A unittest.TestCase
      - `rsc`: A MongoReplicaSetClient
      - `members`: Sequence of host:port expected to be used
      - `mode`: A ReadPreference
      - `tag_sets` (optional): List of dicts of tags for data-center-aware reads
      - `secondary_acceptable_latency_ms` (optional): a float
    """
    members = set(members)
    used = set()
    for _ in range(100):
        used.add(read_from_which_host(rsc, *args, **kwargs))

    testcase.assertEqual(members, used)

def get_pool(client):
    if isinstance(client, MongoClient):
        return client._MongoClient__member.pool
    elif isinstance(client, MongoReplicaSetClient):
        rs_state = client._MongoReplicaSetClient__rs_state
        return rs_state.primary_member.pool
    else:
        raise TypeError(str(client))

def pools_from_rs_client(client):
    """Get Pool instances from a MongoReplicaSetClient or ReplicaSetConnection.
    """
    return [
        member.pool for member in
        client._MongoReplicaSetClient__rs_state.members]

class TestRequestMixin(object):
    """Inherit from this class and from unittest.TestCase to get some
    convenient methods for testing connection pools and requests
    """
    def assertSameSock(self, pool):
        sock_info0 = pool.get_socket()
        sock_info1 = pool.get_socket()
        self.assertEqual(sock_info0, sock_info1)
        pool.maybe_return_socket(sock_info0)
        pool.maybe_return_socket(sock_info1)

    def assertDifferentSock(self, pool):
        sock_info0 = pool.get_socket()
        sock_info1 = pool.get_socket()
        self.assertNotEqual(sock_info0, sock_info1)
        pool.maybe_return_socket(sock_info0)
        pool.maybe_return_socket(sock_info1)

    def assertNoRequest(self, pool):
        self.assertEqual(NO_REQUEST, pool._get_request_state())

    def assertNoSocketYet(self, pool):
        self.assertEqual(NO_SOCKET_YET, pool._get_request_state())

    def assertRequestSocket(self, pool):
        self.assertTrue(isinstance(pool._get_request_state(), SocketInfo))

    def assertInRequestAndSameSock(self, client, pools):
        self.assertTrue(client.in_request())
        if not isinstance(pools, list):
            pools = [pools]
        for pool in pools:
            self.assertTrue(pool.in_request())
            self.assertSameSock(pool)

    def assertNotInRequestAndDifferentSock(self, client, pools):
        self.assertFalse(client.in_request())
        if not isinstance(pools, list):
            pools = [pools]
        for pool in pools:
            self.assertFalse(pool.in_request())
            self.assertDifferentSock(pool)


# Constants for run_threads and _TestLazyConnectMixin.
NTRIALS = 10
NTHREADS = 10


def run_threads(collection, target, use_greenlets):
    """Run a target function in many threads.

    target is a function taking a Collection and an integer.
    """
    threads = []
    for i in range(NTHREADS):
        bound_target = my_partial(target, collection, i)
        if use_greenlets:
            threads.append(gevent.Greenlet(run=bound_target))
        else:
            threads.append(threading.Thread(target=bound_target))

    for t in threads:
        t.start()

    for t in threads:
        t.join(30)
        if use_greenlets:
            # bool(Greenlet) is True if it's alive.
            assert not t
        else:
            assert not t.isAlive()


def lazy_client_trial(reset, target, test, get_client, use_greenlets):
    """Test concurrent operations on a lazily-connecting client.

    `reset` takes a collection and resets it for the next trial.

    `target` takes a lazily-connecting collection and an index from
    0 to NTHREADS, and performs some operation, e.g. an insert.

    `test` takes the lazily-connecting collection and asserts a
    post-condition to prove `target` succeeded.
    """
    if use_greenlets and not has_gevent:
        raise SkipTest('Gevent not installed')

    collection = MongoClient(host, port).pymongo_test.test

    # Make concurrency bugs more likely to manifest.
    interval = None
    if not sys.platform.startswith('java'):
        if sys.version_info >= (3, 2):
            interval = sys.getswitchinterval()
            sys.setswitchinterval(1e-6)
        else:
            interval = sys.getcheckinterval()
            sys.setcheckinterval(1)

    try:
        for i in range(NTRIALS):
            reset(collection)
            lazy_client = get_client(
                _connect=False, use_greenlets=use_greenlets)

            lazy_collection = lazy_client.pymongo_test.test
            run_threads(lazy_collection, target, use_greenlets)
            test(lazy_collection)

    finally:
        if not sys.platform.startswith('java'):
            if sys.version_info >= (3, 2):
                sys.setswitchinterval(interval)
            else:
                sys.setcheckinterval(interval)


class _TestLazyConnectMixin(object):
    """Test concurrent operations on a lazily-connecting client.

    Inherit from this class and from unittest.TestCase, and override
    _get_client(self, **kwargs), for testing a lazily-connecting
    client, i.e. a client initialized with _connect=False.

    Set use_greenlets = True to test with Gevent.
    """
    use_greenlets = False

    NTRIALS = 10
    NTHREADS = 10

    def test_insert(self):
        def reset(collection):
            collection.drop()

        def insert(collection, _):
            collection.insert({})

        def test(collection):
            self.assertEqual(NTHREADS, collection.count())

        lazy_client_trial(
            reset, insert, test,
            self._get_client, self.use_greenlets)

    def test_save(self):
        def reset(collection):
            collection.drop()

        def save(collection, _):
            collection.save({})

        def test(collection):
            self.assertEqual(NTHREADS, collection.count())

        lazy_client_trial(
            reset, save, test,
            self._get_client, self.use_greenlets)

    def test_update(self):
        def reset(collection):
            collection.drop()
            collection.insert([{'i': 0}])

        # Update doc 10 times.
        def update(collection, i):
            collection.update({}, {'$inc': {'i': 1}})

        def test(collection):
            self.assertEqual(NTHREADS, collection.find_one()['i'])

        lazy_client_trial(
            reset, update, test,
            self._get_client, self.use_greenlets)

    def test_remove(self):
        def reset(collection):
            collection.drop()
            collection.insert([{'i': i} for i in range(NTHREADS)])

        def remove(collection, i):
            collection.remove({'i': i})

        def test(collection):
            self.assertEqual(0, collection.count())

        lazy_client_trial(
            reset, remove, test,
            self._get_client, self.use_greenlets)

    def test_find_one(self):
        results = []

        def reset(collection):
            collection.drop()
            collection.insert({})
            results[:] = []

        def find_one(collection, _):
            results.append(collection.find_one())

        def test(collection):
            self.assertEqual(NTHREADS, len(results))

        lazy_client_trial(
            reset, find_one, test,
            self._get_client, self.use_greenlets)

    def test_max_bson_size(self):
        # Client should have sane defaults before connecting, and should update
        # its configuration once connected.
        c = self._get_client(_connect=False)
        self.assertEqual(16 * (1024 ** 2), c.max_bson_size)
        self.assertEqual(2 * c.max_bson_size, c.max_message_size)

        # Make the client connect, so that it sets its max_bson_size and
        # max_message_size attributes.
        ismaster = c.db.command('ismaster')
        self.assertEqual(ismaster['maxBsonObjectSize'], c.max_bson_size)
        if 'maxMessageSizeBytes' in ismaster:
            self.assertEqual(
                ismaster['maxMessageSizeBytes'],
                c.max_message_size)