openstack/swift
Code Issues Proposed changes

memcached: encapsulate common command parameters

Browse Source 
Introduce a MemcacheCommand class to encapsulate some of the common
parameters and functionality associated with the MemcacheRing methods.

No behavioural changes.

Change-Id: I2a84d5b74d74967628973ad5d67749b787ba7590
Related-Change: I4d4f20b92b85255ac8bf66f2c830e691e64bbe47
Related-Change: I07491bb4ebc3baa13cf09f64a04a61011d561409
This commit is contained in:
Alistair Coles
2023-05-18 12:21:31 +01:00
parent 8909604540
commit f714f43c90
2 changed files with 122 additions and 112 deletions
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171
swift/common/memcached.py
View File

@@ -119,13 +119,6 @@ def set_msg(key, flags, timeout, value):
]) + (b'\r\n' + value + b'\r\n')
# get the prefix of a user provided memcache key by removing the content after
# the last '/', all current usages within swift are using prefix, such as
# "shard-updating-v2", "nvratelimit" and etc.
def get_key_prefix(key):
return key.rsplit('/', 1)[0]
class MemcacheConnectionError(Exception):
pass
@@ -183,6 +176,29 @@ class MemcacheConnPool(Pool):
raise
class MemcacheCommand(object):
"""
Helper class that encapsulates common parameters of a command.
:param method: the name of the MemcacheRing method that was called.
:param key: the memcached key.
"""
__slots__ = ('method', 'key', 'command', 'hash_key')
def __init__(self, method, key):
self.method = method
self.key = key
self.command = method.encode()
self.hash_key = md5hash(key)
@property
def key_prefix(self):
# get the prefix of a user provided memcache key by removing the
# content after the last '/', all current usages within swift are using
# prefix, such as "shard-updating-v2", "nvratelimit" and etc.
return self.key.rsplit('/', 1)[0]
class MemcacheRing(object):
"""
Simple, consistent-hashed memcache client.
@@ -225,8 +241,21 @@ class MemcacheRing(object):
def memcache_servers(self):
return list(self._client_cache.keys())
def _exception_occurred(self, server, e, key_prefix, method,
conn_start_time, action='talking', sock=None,
"""
Handles exceptions.
:param server: a server.
:param e: an exception.
:param cmd: an instance of MemcacheCommand.
:param conn_start_time: the time at which the failed operation started.
:param action: a verb describing the operation.
:param sock: an optional socket that needs to be closed by this method.
:param fp: an optional file pointer that needs to be closed by this method.
:param got_connection: if ``True``, the server's connection will be reset
in the cached connection pool.
"""
def _exception_occurred(self, server, e, cmd, conn_start_time,
action='talking', sock=None,
fp=None, got_connection=True):
if isinstance(e, Timeout):
self.logger.error(
@@ -234,28 +263,30 @@ class MemcacheRing(object):
": with key_prefix %(key_prefix)s, method %(method)s, "
"config_timeout %(config_timeout)s, time_spent %(time_spent)s",
{'action': action, 'server': server,
'key_prefix': key_prefix, 'method': method,
'key_prefix': cmd.key_prefix, 'method': cmd.method,
'config_timeout': e.seconds,
'time_spent': tm.time() - conn_start_time})
self.logger.timing_since(
'memcached.' + method + '.timeout.timing', conn_start_time)
'memcached.' + cmd.method + '.timeout.timing',
conn_start_time)
elif isinstance(e, (socket.error, MemcacheConnectionError)):
self.logger.error(
"Error %(action)s to memcached: %(server)s: "
"with key_prefix %(key_prefix)s, method %(method)s, "
"time_spent %(time_spent)s, %(err)s",
{'action': action, 'server': server,
'key_prefix': key_prefix, 'method': method,
'key_prefix': cmd.key_prefix, 'method': cmd.method,
'time_spent': tm.time() - conn_start_time, 'err': e})
self.logger.timing_since(
'memcached.' + method + '.conn_err.timing', conn_start_time)
'memcached.' + cmd.method + '.conn_err.timing',
conn_start_time)
else:
self.logger.exception("Error %(action)s to memcached: %(server)s"
": with key_prefix %(key_prefix)s",
{'action': action, 'server': server,
'key_prefix': key_prefix})
'key_prefix': cmd.key_prefix})
self.logger.timing_since(
'memcached.' + method + '.errors.timing', conn_start_time)
'memcached.' + cmd.method + '.errors.timing', conn_start_time)
try:
if fp:
@@ -286,18 +317,15 @@ class MemcacheRing(object):
self._error_limited[server] = now + self._error_limit_duration
self.logger.error('Error limiting server %s', server)
def _get_conns(self, method, key_prefix, hash_key):
def _get_conns(self, cmd):
"""
Retrieves a server conn from the pool, or connects a new one.
Chooses the server based on a consistent hash of "key".
:param method: the name of memcache method.
:param key_prefix: the prefix of user provided key.
:param hash_key: the consistent hash of user key, or server key for
set_multi and get_multi.
:param cmd: an instance of MemcacheCommand.
:return: generator to serve memcached connection
"""
pos = bisect(self._sorted, hash_key)
pos = bisect(self._sorted, cmd.hash_key)
served = []
any_yielded = False
while len(served) < self._tries:
@@ -316,16 +344,15 @@ class MemcacheRing(object):
any_yielded = True
yield server, fp, sock
except MemcachePoolTimeout as e:
self._exception_occurred(
server, e, key_prefix, method, pool_start_time,
action='getting a connection', got_connection=False)
self._exception_occurred(server, e, cmd, pool_start_time,
action='getting a connection',
got_connection=False)
except (Exception, Timeout) as e:
# Typically a Timeout exception caught here is the one raised
# by the create() method of this server's MemcacheConnPool
# object.
self._exception_occurred(
server, e, key_prefix, method, pool_start_time,
action='connecting', sock=sock)
self._exception_occurred(server, e, cmd, pool_start_time,
action='connecting', sock=sock)
if not any_yielded:
self.logger.error('All memcached servers error-limited')
@@ -353,8 +380,7 @@ class MemcacheRing(object):
:param raise_on_error: if True, propagate Timeouts and other errors.
By default, errors are ignored.
"""
key_prefix = get_key_prefix(key)
hash_key = md5hash(key)
cmd = MemcacheCommand('set', key)
timeout = sanitize_timeout(time)
flags = 0
if serialize:
@@ -365,11 +391,11 @@ class MemcacheRing(object):
elif not isinstance(value, bytes):
value = str(value).encode('utf-8')
for (server, fp, sock) in self._get_conns('set', key_prefix, hash_key):
for (server, fp, sock) in self._get_conns(cmd):
conn_start_time = tm.time()
try:
with Timeout(self._io_timeout):
sock.sendall(set_msg(hash_key, flags, timeout, value))
sock.sendall(set_msg(cmd.hash_key, flags, timeout, value))
# Wait for the set to complete
msg = fp.readline().strip()
if msg != b'STORED':
@@ -389,9 +415,8 @@ class MemcacheRing(object):
self._return_conn(server, fp, sock)
return
except (Exception, Timeout) as e:
self._exception_occurred(
server, e, key_prefix, 'set', conn_start_time,
sock=sock, fp=fp)
self._exception_occurred(server, e, cmd, conn_start_time,
sock=sock, fp=fp)
if raise_on_error:
raise MemcacheConnectionError(
"No memcached connections succeeded.")
@@ -407,21 +432,21 @@ class MemcacheRing(object):
By default, errors are treated as cache misses.
:returns: value of the key in memcache
"""
key_prefix = get_key_prefix(key)
hash_key = md5hash(key)
cmd = MemcacheCommand('get', key)
value = None
for (server, fp, sock) in self._get_conns('get', key_prefix, hash_key):
for (server, fp, sock) in self._get_conns(cmd):
conn_start_time = tm.time()
try:
with Timeout(self._io_timeout):
sock.sendall(b'get ' + hash_key + b'\r\n')
sock.sendall(b'get ' + cmd.hash_key + b'\r\n')
line = fp.readline().strip().split()
while True:
if not line:
raise MemcacheConnectionError('incomplete read')
if line[0].upper() == b'END':
break
if line[0].upper() == b'VALUE' and line[1] == hash_key:
if (line[0].upper() == b'VALUE' and
line[1] == cmd.hash_key):
size = int(line[3])
value = fp.read(size)
if int(line[2]) & PICKLE_FLAG:
@@ -433,9 +458,8 @@ class MemcacheRing(object):
self._return_conn(server, fp, sock)
return value
except (Exception, Timeout) as e:
self._exception_occurred(
server, e, key_prefix, 'get', conn_start_time,
sock=sock, fp=fp)
self._exception_occurred(server, e, cmd, conn_start_time,
sock=sock, fp=fp)
if raise_on_error:
raise MemcacheConnectionError(
"No memcached connections succeeded.")
@@ -458,38 +482,32 @@ class MemcacheRing(object):
:returns: result of incrementing
:raises MemcacheConnectionError:
"""
key_prefix = get_key_prefix(key)
hash_key = md5hash(key)
command = b'incr'
if delta < 0:
command = b'decr'
cmd = MemcacheCommand('incr' if delta >= 0 else 'decr', key)
delta = str(abs(int(delta))).encode('ascii')
timeout = sanitize_timeout(time)
method = command.decode()
for (server, fp, sock) in self._get_conns(method, key_prefix,
hash_key):
for (server, fp, sock) in self._get_conns(cmd):
conn_start_time = tm.time()
try:
with Timeout(self._io_timeout):
sock.sendall(b' '.join([
command, hash_key, delta]) + b'\r\n')
cmd.command, cmd.hash_key, delta]) + b'\r\n')
line = fp.readline().strip().split()
if not line:
raise MemcacheConnectionError('incomplete read')
if line[0].upper() == b'NOT_FOUND':
add_val = delta
if command == b'decr':
if cmd.command == b'decr':
add_val = b'0'
sock.sendall(
b' '.join(
[b'add', hash_key, b'0', str(timeout).encode(
'ascii'),
[b'add', cmd.hash_key, b'0',
str(timeout).encode('ascii'),
str(len(add_val)).encode('ascii')
]) + b'\r\n' + add_val + b'\r\n')
line = fp.readline().strip().split()
if line[0].upper() == b'NOT_STORED':
sock.sendall(b' '.join([
command, hash_key, delta]) + b'\r\n')
cmd.command, cmd.hash_key, delta]) + b'\r\n')
line = fp.readline().strip().split()
ret = int(line[0].strip())
else:
@@ -499,9 +517,8 @@ class MemcacheRing(object):
self._return_conn(server, fp, sock)
return ret
except (Exception, Timeout) as e:
self._exception_occurred(
server, e, key_prefix, method, conn_start_time,
sock=sock, fp=fp)
self._exception_occurred(server, e, cmd, conn_start_time,
sock=sock, fp=fp)
raise MemcacheConnectionError("No memcached connections succeeded.")
@memcached_timing_stats(sample_rate=TIMING_SAMPLE_RATE_LOW)
@@ -529,23 +546,21 @@ class MemcacheRing(object):
:param server_key: key to use in determining which server in the ring
is used
"""
key_prefix = get_key_prefix(key)
hash_key = md5hash(key)
server_key = md5hash(server_key) if server_key else hash_key
for (server, fp, sock) in self._get_conns('delete', key_prefix,
server_key):
cmd = server_cmd = MemcacheCommand('delete', key)
if server_key:
server_cmd = MemcacheCommand('delete', server_key)
for (server, fp, sock) in self._get_conns(server_cmd):
conn_start_time = tm.time()
try:
with Timeout(self._io_timeout):
sock.sendall(b'delete ' + hash_key + b'\r\n')
sock.sendall(b'delete ' + cmd.hash_key + b'\r\n')
# Wait for the delete to complete
fp.readline()
self._return_conn(server, fp, sock)
return
except (Exception, Timeout) as e:
self._exception_occurred(
server, e, key_prefix, 'delete', conn_start_time,
sock=sock, fp=fp)
self._exception_occurred(server, e, cmd, conn_start_time,
sock=sock, fp=fp)
@memcached_timing_stats(sample_rate=TIMING_SAMPLE_RATE_HIGH)
def set_multi(self, mapping, server_key, serialize=True, time=0,
@@ -564,8 +579,7 @@ class MemcacheRing(object):
python-memcached interface. This implementation
ignores it
"""
key_prefix = get_key_prefix(server_key)
hash_key = md5hash(server_key)
cmd = MemcacheCommand('set_multi', server_key)
timeout = sanitize_timeout(time)
msg = []
for key, value in mapping.items():
@@ -577,8 +591,7 @@ class MemcacheRing(object):
value = json.dumps(value).encode('ascii')
flags |= JSON_FLAG
msg.append(set_msg(key, flags, timeout, value))
for (server, fp, sock) in self._get_conns('set_multi', key_prefix,
hash_key):
for (server, fp, sock) in self._get_conns(cmd):
conn_start_time = tm.time()
try:
with Timeout(self._io_timeout):
@@ -589,9 +602,8 @@ class MemcacheRing(object):
self._return_conn(server, fp, sock)
return
except (Exception, Timeout) as e:
self._exception_occurred(
server, e, key_prefix, 'set_multi', conn_start_time,
sock=sock, fp=fp)
self._exception_occurred(server, e, cmd, conn_start_time,
sock=sock, fp=fp)
@memcached_timing_stats(sample_rate=TIMING_SAMPLE_RATE_HIGH)
def get_multi(self, keys, server_key):
@@ -603,11 +615,9 @@ class MemcacheRing(object):
is used
:returns: list of values
"""
key_prefix = get_key_prefix(server_key)
server_key = md5hash(server_key)
cmd = MemcacheCommand('get_multi', server_key)
hash_keys = [md5hash(key) for key in keys]
for (server, fp, sock) in self._get_conns('get_multi', key_prefix,
server_key):
for (server, fp, sock) in self._get_conns(cmd):
conn_start_time = tm.time()
try:
with Timeout(self._io_timeout):
@@ -638,9 +648,8 @@ class MemcacheRing(object):
self._return_conn(server, fp, sock)
return values
except (Exception, Timeout) as e:
self._exception_occurred(
server, e, key_prefix, 'get_multi', conn_start_time,
sock=sock, fp=fp)
self._exception_occurred(server, e, cmd, conn_start_time,
sock=sock, fp=fp)
def load_memcache(conf, logger):

63
test/unit/common/test_memcached.py
View File

@@ -24,7 +24,6 @@ import six
import socket
import time
import unittest
from uuid import uuid4
import os
import mock
@@ -36,7 +35,7 @@ from eventlet.green import ssl
from swift.common import memcached
from swift.common.memcached import MemcacheConnectionError, md5hash, \
get_key_prefix
MemcacheCommand
from swift.common.utils import md5, human_readable
from mock import patch, MagicMock
from test.debug_logger import debug_logger
@@ -196,26 +195,35 @@ class MockMemcached(object):
pass
class TestMemcacheCommand(unittest.TestCase):
def test_init(self):
cmd = MemcacheCommand("set", "shard-updating-v2/a/c")
self.assertEqual(cmd.method, "set")
self.assertEqual(cmd.command, b"set")
self.assertEqual(cmd.key, "shard-updating-v2/a/c")
self.assertEqual(cmd.key_prefix, "shard-updating-v2/a")
self.assertEqual(cmd.hash_key, md5hash("shard-updating-v2/a/c"))
def test_get_key_prefix(self):
cmd = MemcacheCommand("set", "shard-updating-v2/a/c")
self.assertEqual(cmd.key_prefix, "shard-updating-v2/a")
cmd = MemcacheCommand("set", "shard-listing-v2/accout/container3")
self.assertEqual(cmd.key_prefix, "shard-listing-v2/accout")
cmd = MemcacheCommand(
"set", "auth_reseller_name/token/X58E34EL2SDFLEY3")
self.assertEqual(cmd.key_prefix, "auth_reseller_name/token")
cmd = MemcacheCommand("set", "nvratelimit/v2/wf/2345392374")
self.assertEqual(cmd.key_prefix, "nvratelimit/v2/wf")
cmd = MemcacheCommand("set", "some_key")
self.assertEqual(cmd.key_prefix, "some_key")
class TestMemcached(unittest.TestCase):
"""Tests for swift.common.memcached"""
def setUp(self):
self.logger = debug_logger()
def test_get_key_prefix(self):
self.assertEqual(
get_key_prefix("shard-updating-v2/a/c"),
"shard-updating-v2/a")
self.assertEqual(
get_key_prefix("shard-listing-v2/accout/container3"),
"shard-listing-v2/accout")
self.assertEqual(
get_key_prefix("auth_reseller_name/token/X58E34EL2SDFLEY3"),
"auth_reseller_name/token")
self.assertEqual(
get_key_prefix("nvratelimit/v2/wf/2345392374"),
"nvratelimit/v2/wf")
self.assertEqual(get_key_prefix("some_key"), "some_key")
self.set_cmd = MemcacheCommand('set', 'key')
def test_logger_kwarg(self):
server_socket = '%s:%s' % ('[::1]', 11211)
@@ -235,8 +243,7 @@ class TestMemcached(unittest.TestCase):
client = memcached.MemcacheRing([server], tls_context=context)
self.assertIs(client._client_cache[server]._tls_context, context)
key = uuid4().hex.encode('ascii')
list(client._get_conns('set', 'test', key))
list(client._get_conns(self.set_cmd))
context.wrap_socket.assert_called_once()
def test_get_conns(self):
@@ -257,8 +264,7 @@ class TestMemcached(unittest.TestCase):
logger=self.logger)
one = two = True
while one or two: # Run until we match hosts one and two
key = uuid4().hex.encode('ascii')
for conn in memcache_client._get_conns('set', 'test', key):
for conn in memcache_client._get_conns(self.set_cmd):
if 'b' not in getattr(conn[1], 'mode', ''):
self.assertIsInstance(conn[1], (
io.RawIOBase, io.BufferedIOBase))
@@ -284,8 +290,7 @@ class TestMemcached(unittest.TestCase):
server_socket = '[%s]:%s' % (sock_addr[0], sock_addr[1])
memcache_client = memcached.MemcacheRing([server_socket],
logger=self.logger)
key = uuid4().hex.encode('ascii')
for conn in memcache_client._get_conns('set', 'test', key):
for conn in memcache_client._get_conns(self.set_cmd):
peer_sockaddr = conn[2].getpeername()
peer_socket = '[%s]:%s' % (peer_sockaddr[0], peer_sockaddr[1])
self.assertEqual(peer_socket, server_socket)
@@ -306,8 +311,7 @@ class TestMemcached(unittest.TestCase):
memcached.DEFAULT_MEMCACHED_PORT = sock_addr[1]
memcache_client = memcached.MemcacheRing([server_host],
logger=self.logger)
key = uuid4().hex.encode('ascii')
for conn in memcache_client._get_conns('set', 'test', key):
for conn in memcache_client._get_conns(self.set_cmd):
peer_sockaddr = conn[2].getpeername()
peer_socket = '[%s]:%s' % (peer_sockaddr[0], peer_sockaddr[1])
self.assertEqual(peer_socket, server_socket)
@@ -335,8 +339,7 @@ class TestMemcached(unittest.TestCase):
('127.0.0.1', sock_addr[1]))]
memcache_client = memcached.MemcacheRing([server_socket],
logger=self.logger)
key = uuid4().hex.encode('ascii')
for conn in memcache_client._get_conns('set', 'test', key):
for conn in memcache_client._get_conns(self.set_cmd):
peer_sockaddr = conn[2].getpeername()
peer_socket = '%s:%s' % (peer_sockaddr[0],
peer_sockaddr[1])
@@ -361,8 +364,7 @@ class TestMemcached(unittest.TestCase):
('::1', sock_addr[1]))]
memcache_client = memcached.MemcacheRing([server_socket],
logger=self.logger)
key = uuid4().hex.encode('ascii')
for conn in memcache_client._get_conns('set', 'test', key):
for conn in memcache_client._get_conns(self.set_cmd):
peer_sockaddr = conn[2].getpeername()
peer_socket = '[%s]:%s' % (peer_sockaddr[0],
peer_sockaddr[1])
@@ -1066,8 +1068,7 @@ class TestMemcached(unittest.TestCase):
# try to get connect and no connection found
# so it will result in StopIteration
conn_generator = memcache_client._get_conns(
'set', 'key', md5hash(b'key'))
conn_generator = memcache_client._get_conns(self.set_cmd)
with self.assertRaises(StopIteration):
next(conn_generator)