from itertools import chain
import os
import socket
import sys
from ledis._compat import (b, xrange, imap, byte_to_chr, unicode, bytes, long,
BytesIO, nativestr, basestring, iteritems,
LifoQueue, Empty, Full, urlparse, parse_qs)
from ledis.exceptions import (
LedisError,
ConnectionError,
BusyLoadingError,
ResponseError,
InvalidResponse,
ExecAbortError,
)
SYM_STAR = b('*')
SYM_DOLLAR = b('$')
SYM_CRLF = b('\r\n')
SYM_LF = b('\n')
class PythonParser(object):
"Plain Python parsing class"
MAX_READ_LENGTH = 1000000
encoding = None
EXCEPTION_CLASSES = {
'ERR': ResponseError,
'EXECABORT': ExecAbortError,
'LOADING': BusyLoadingError,
}
def __init__(self):
self._fp = None
def __del__(self):
try:
self.on_disconnect()
except Exception:
pass
def on_connect(self, connection):
"Called when the socket connects"
self._fp = connection._sock.makefile('rb')
if connection.decode_responses:
self.encoding = connection.encoding
def on_disconnect(self):
"Called when the socket disconnects"
if self._fp is not None:
self._fp.close()
self._fp = None
def read(self, length=None):
"""
Read a line from the socket if no length is specified,
otherwise read ``length`` bytes. Always strip away the newlines.
"""
try:
if length is not None:
bytes_left = length + 2 # read the line ending
if length > self.MAX_READ_LENGTH:
# apparently reading more than 1MB or so from a windows
# socket can cause MemoryErrors. See:
# https://github.com/andymccurdy/redis-py/issues/205
# read smaller chunks at a time to work around this
try:
buf = BytesIO()
while bytes_left > 0:
read_len = min(bytes_left, self.MAX_READ_LENGTH)
buf.write(self._fp.read(read_len))
bytes_left -= read_len
buf.seek(0)
return buf.read(length)
finally:
buf.close()
return self._fp.read(bytes_left)[:-2]
# no length, read a full line
return self._fp.readline()[:-2]
except (socket.error, socket.timeout):
e = sys.exc_info()[1]
raise ConnectionError("Error while reading from socket: %s" %
(e.args,))
def parse_error(self, response):
"Parse an error response"
error_code = response.split(' ')[0]
if error_code in self.EXCEPTION_CLASSES:
response = response[len(error_code) + 1:]
return self.EXCEPTION_CLASSES[error_code](response)
return ResponseError(response)
def read_response(self):
response = self.read()
if not response:
raise ConnectionError("Socket closed on remote end")
byte, response = byte_to_chr(response[0]), response[1:]
if byte not in ('-', '+', ':', '$', '*'):
raise InvalidResponse("Protocol Error")
# server returned an error
if byte == '-':
response = nativestr(response)
error = self.parse_error(response)
# if the error is a ConnectionError, raise immediately so the user
# is notified
if isinstance(error, ConnectionError):
raise error
# otherwise, we're dealing with a ResponseError that might belong
# inside a pipeline response. the connection's read_response()
# and/or the pipeline's execute() will raise this error if
# necessary, so just return the exception instance here.
return error
# single value
elif byte == '+':
pass
# int value
elif byte == ':':
response = long(response)
# bulk response
elif byte == '$':
length = int(response)
if length == -1:
return None
response = self.read(length)
# multi-bulk response
elif byte == '*':
length = int(response)
if length == -1:
return None
response = [self.read_response() for i in xrange(length)]
if isinstance(response, bytes) and self.encoding:
response = response.decode(self.encoding)
return response
DefaultParser = PythonParser
[docs]class Connection(object):
"Manages TCP communication to and from a Ledis server"
def __init__(self, host='localhost', port=6380, db=0,
socket_timeout=None, encoding='utf-8',
encoding_errors='strict', decode_responses=False,
parser_class=DefaultParser):
self.pid = os.getpid()
self.host = host
self.port = port
self.db = db
self.socket_timeout = socket_timeout
self.encoding = encoding
self.encoding_errors = encoding_errors
self.decode_responses = decode_responses
self._sock = None
self._parser = parser_class()
def __del__(self):
try:
self.disconnect()
except Exception:
pass
[docs] def connect(self):
"Connects to the Ledis server if not already connected"
if self._sock:
return
try:
sock = self._connect()
except socket.error:
e = sys.exc_info()[1]
raise ConnectionError(self._error_message(e))
self._sock = sock
self.on_connect()
def _connect(self):
"Create a TCP socket connection"
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.settimeout(self.socket_timeout)
sock.connect((self.host, self.port))
return sock
def _error_message(self, exception):
# args for socket.error can either be (errno, "message")
# or just "message"
if len(exception.args) == 1:
return "Error connecting to %s:%s. %s." % \
(self.host, self.port, exception.args[0])
else:
return "Error %s connecting %s:%s. %s." % \
(exception.args[0], self.host, self.port, exception.args[1])
[docs] def on_connect(self):
"Initialize the connection, authenticate and select a database"
self._parser.on_connect(self)
# if a database is specified, switch to it
if self.db:
self.send_command('SELECT', self.db)
if nativestr(self.read_response()) != 'OK':
raise ConnectionError('Invalid Database')
[docs] def disconnect(self):
"Disconnects from the Ledis server"
self._parser.on_disconnect()
if self._sock is None:
return
try:
self._sock.close()
except socket.error:
pass
self._sock = None
[docs] def send_packed_command(self, command):
"Send an already packed command to the Ledis server"
if not self._sock:
self.connect()
try:
self._sock.sendall(command)
except socket.error:
e = sys.exc_info()[1]
self.disconnect()
if len(e.args) == 1:
_errno, errmsg = 'UNKNOWN', e.args[0]
else:
_errno, errmsg = e.args
raise ConnectionError("Error %s while writing to socket. %s." %
(_errno, errmsg))
except Exception:
self.disconnect()
raise
[docs] def send_command(self, *args):
"Pack and send a command to the Ledis server"
self.send_packed_command(self.pack_command(*args))
[docs] def read_response(self):
"Read the response from a previously sent command"
try:
response = self._parser.read_response()
except Exception:
self.disconnect()
raise
if isinstance(response, ResponseError):
raise response
return response
[docs] def encode(self, value):
"Return a bytestring representation of the value"
if isinstance(value, bytes):
return value
if isinstance(value, float):
value = repr(value)
if not isinstance(value, basestring):
value = str(value)
if isinstance(value, unicode):
value = value.encode(self.encoding, self.encoding_errors)
return value
[docs] def pack_command(self, *args):
"Pack a series of arguments into a value Ledis command"
output = SYM_STAR + b(str(len(args))) + SYM_CRLF
for enc_value in imap(self.encode, args):
output += SYM_DOLLAR
output += b(str(len(enc_value)))
output += SYM_CRLF
output += enc_value
output += SYM_CRLF
return output
class UnixDomainSocketConnection(Connection):
def __init__(self, path='', db=0, socket_timeout=None, encoding='utf-8',
encoding_errors='strict', decode_responses=False,
parser_class=DefaultParser):
self.pid = os.getpid()
self.path = path
self.db = db
self.socket_timeout = socket_timeout
self.encoding = encoding
self.encoding_errors = encoding_errors
self.decode_responses = decode_responses
self._sock = None
self._parser = parser_class()
def _connect(self):
"Create a Unix domain socket connection"
sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
sock.settimeout(self.socket_timeout)
sock.connect(self.path)
return sock
def _error_message(self, exception):
# args for socket.error can either be (errno, "message")
# or just "message"
if len(exception.args) == 1:
return "Error connecting to unix socket: %s. %s." % \
(self.path, exception.args[0])
else:
return "Error %s connecting to unix socket: %s. %s." % \
(exception.args[0], self.path, exception.args[1])
# TODO: add ability to block waiting on a connection to be released
[docs]class ConnectionPool(object):
"Generic connection pool"
@classmethod
[docs] def from_url(cls, url, db=None, **kwargs):
"""
Return a connection pool configured from the given URL.
For example::
ledis://localhost:6380/0
unix:///path/to/socket.sock?db=0
Three URL schemes are supported:
ledis:// creates a normal TCP socket connection
unix:// creates a Unix Domain Socket connection
There are several ways to specify a database number. The parse function
will return the first specified option:
1. A ``db`` querystring option, e.g. ledis://localhost?db=0
2. If using the ledis:// scheme, the path argument of the url, e.g.
ledis://localhost/0
3. The ``db`` argument to this function.
If none of these options are specified, db=0 is used.
Any additional querystring arguments and keyword arguments will be
passed along to the ConnectionPool class's initializer. In the case
of conflicting arguments, querystring arguments always win.
"""
url_string = url
url = urlparse(url)
qs = ''
# in python2.6, custom URL schemes don't recognize querystring values
# they're left as part of the url.path.
if '?' in url.path and not url.query:
# chop the querystring including the ? off the end of the url
# and reparse it.
qs = url.path.split('?', 1)[1]
url = urlparse(url_string[:-(len(qs) + 1)])
else:
qs = url.query
url_options = {}
for name, value in iteritems(parse_qs(qs)):
if value and len(value) > 0:
url_options[name] = value[0]
# We only support ledis:// and unix:// schemes.
if url.scheme == 'unix':
url_options.update({
'path': url.path,
'connection_class': UnixDomainSocketConnection,
})
else:
url_options.update({
'host': url.hostname,
'port': int(url.port or 6380),
})
# If there's a path argument, use it as the db argument if a
# querystring value wasn't specified
if 'db' not in url_options and url.path:
try:
url_options['db'] = int(url.path.replace('/', ''))
except (AttributeError, ValueError):
pass
# last shot at the db value
url_options['db'] = int(url_options.get('db', db or 0))
# update the arguments from the URL values
kwargs.update(url_options)
return cls(**kwargs)
def __init__(self, connection_class=Connection, max_connections=None,
**connection_kwargs):
self.pid = os.getpid()
self.connection_class = connection_class
self.connection_kwargs = connection_kwargs
self.max_connections = max_connections or 2 ** 31
self._created_connections = 0
self._available_connections = []
self._in_use_connections = set()
def _checkpid(self):
if self.pid != os.getpid():
self.disconnect()
self.__init__(self.connection_class, self.max_connections,
**self.connection_kwargs)
[docs] def get_connection(self, command_name, *keys, **options):
"Get a connection from the pool"
self._checkpid()
try:
connection = self._available_connections.pop()
except IndexError:
connection = self.make_connection()
self._in_use_connections.add(connection)
return connection
[docs] def make_connection(self):
"Create a new connection"
if self._created_connections >= self.max_connections:
raise ConnectionError("Too many connections")
self._created_connections += 1
return self.connection_class(**self.connection_kwargs)
[docs] def release(self, connection):
"Releases the connection back to the pool"
self._checkpid()
if connection.pid == self.pid:
self._in_use_connections.remove(connection)
self._available_connections.append(connection)
[docs] def disconnect(self):
"Disconnects all connections in the pool"
all_conns = chain(self._available_connections,
self._in_use_connections)
for connection in all_conns:
connection.disconnect()
[docs]class BlockingConnectionPool(object):
"""
Thread-safe blocking connection pool::
>>> from ledis.client import Ledis
>>> client = Ledis(connection_pool=BlockingConnectionPool())
It performs the same function as the default
``:py:class: ~ledis.connection.ConnectionPool`` implementation, in that,
it maintains a pool of reusable connections that can be shared by
multiple ledis clients (safely across threads if required).
The difference is that, in the event that a client tries to get a
connection from the pool when all of connections are in use, rather than
raising a ``:py:class: ~ledis.exceptions.ConnectionError`` (as the default
``:py:class: ~ledis.connection.ConnectionPool`` implementation does), it
makes the client wait ("blocks") for a specified number of seconds until
a connection becomes available.
Use ``max_connections`` to increase / decrease the pool size::
>>> pool = BlockingConnectionPool(max_connections=10)
Use ``timeout`` to tell it either how many seconds to wait for a connection
to become available, or to block forever:
# Block forever.
>>> pool = BlockingConnectionPool(timeout=None)
# Raise a ``ConnectionError`` after five seconds if a connection is
# not available.
>>> pool = BlockingConnectionPool(timeout=5)
"""
def __init__(self, max_connections=50, timeout=20, connection_class=None,
queue_class=None, **connection_kwargs):
"Compose and assign values."
# Compose.
if connection_class is None:
connection_class = Connection
if queue_class is None:
queue_class = LifoQueue
# Assign.
self.connection_class = connection_class
self.connection_kwargs = connection_kwargs
self.queue_class = queue_class
self.max_connections = max_connections
self.timeout = timeout
# Validate the ``max_connections``. With the "fill up the queue"
# algorithm we use, it must be a positive integer.
is_valid = isinstance(max_connections, int) and max_connections > 0
if not is_valid:
raise ValueError('``max_connections`` must be a positive integer')
# Get the current process id, so we can disconnect and reinstantiate if
# it changes.
self.pid = os.getpid()
# Create and fill up a thread safe queue with ``None`` values.
self.pool = self.queue_class(max_connections)
while True:
try:
self.pool.put_nowait(None)
except Full:
break
# Keep a list of actual connection instances so that we can
# disconnect them later.
self._connections = []
def _checkpid(self):
"""
Check the current process id. If it has changed, disconnect and
re-instantiate this connection pool instance.
"""
# Get the current process id.
pid = os.getpid()
# If it hasn't changed since we were instantiated, then we're fine, so
# just exit, remaining connected.
if self.pid == pid:
return
# If it has changed, then disconnect and re-instantiate.
self.disconnect()
self.reinstantiate()
[docs] def make_connection(self):
"Make a fresh connection."
connection = self.connection_class(**self.connection_kwargs)
self._connections.append(connection)
return connection
[docs] def get_connection(self, command_name, *keys, **options):
"""
Get a connection, blocking for ``self.timeout`` until a connection
is available from the pool.
If the connection returned is ``None`` then creates a new connection.
Because we use a last-in first-out queue, the existing connections
(having been returned to the pool after the initial ``None`` values
were added) will be returned before ``None`` values. This means we only
create new connections when we need to, i.e.: the actual number of
connections will only increase in response to demand.
"""
# Make sure we haven't changed process.
self._checkpid()
# Try and get a connection from the pool. If one isn't available within
# self.timeout then raise a ``ConnectionError``.
connection = None
try:
connection = self.pool.get(block=True, timeout=self.timeout)
except Empty:
# Note that this is not caught by the ledis client and will be
# raised unless handled by application code. If you want never to
raise ConnectionError("No connection available.")
# If the ``connection`` is actually ``None`` then that's a cue to make
# a new connection to add to the pool.
if connection is None:
connection = self.make_connection()
return connection
[docs] def release(self, connection):
"Releases the connection back to the pool."
# Make sure we haven't changed process.
self._checkpid()
# Put the connection back into the pool.
try:
self.pool.put_nowait(connection)
except Full:
# This shouldn't normally happen but might perhaps happen after a
# reinstantiation. So, we can handle the exception by not putting
# the connection back on the pool, because we definitely do not
# want to reuse it.
pass
[docs] def disconnect(self):
"Disconnects all connections in the pool."
for connection in self._connections:
connection.disconnect()
[docs] def reinstantiate(self):
"""
Reinstatiate this instance within a new process with a new connection
pool set.
"""
self.__init__(max_connections=self.max_connections,
timeout=self.timeout,
connection_class=self.connection_class,
queue_class=self.queue_class, **self.connection_kwargs)
class Token(object):
"""
Literal strings in Redis commands, such as the command names and any
hard-coded arguments are wrapped in this class so we know not to apply
and encoding rules on them.
"""
def __init__(self, value):
if isinstance(value, Token):
value = value.value
self.value = value
def __repr__(self):
return self.value
def __str__(self):
return self.value