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import errno
import os
import socket
from itertools import chain, imap
from redis.exceptions import ConnectionError, ResponseError, InvalidResponse
class PythonParser(object):
def on_connect(self, connection):
"Called when the socket connects"
self._fp = connection._sock.makefile('r')
def on_disconnect(self):
"Called when the socket disconnects"
self._fp.close()
self._fp = None
def read(self, length=None):
"""
Read a line from the socket is no length is specified,
otherwise read ``length`` bytes. Always strip away the newlines.
"""
try:
if length is not None:
return self._fp.read(length+2)[:-2]
return self._fp.readline()[:-2]
except (socket.error, socket.timeout), e:
raise ConnectionError("Error while reading from socket: %s" % \
(e.args,))
def read_response(self):
response = self.read()
if not response:
raise ConnectionError("Socket closed on remote end")
byte, response = response[0], response[1:]
# server returned an error
if byte == '-':
if response.startswith('ERR '):
response = response[4:]
return ResponseError(response)
if response.startswith('LOADING '):
# If we're loading the dataset into memory, kill the socket
# so we re-initialize (and re-SELECT) next time.
raise ConnectionError("Redis is loading data into memory")
# single value
elif byte == '+':
return response
# int value
elif byte == ':':
return long(response)
# bulk response
elif byte == '$':
length = int(response)
if length == -1:
return None
response = length and self.read(length) or ''
return response
# multi-bulk response
elif byte == '*':
length = int(response)
if length == -1:
return None
return [self.read_response() for i in xrange(length)]
raise InvalidResponse("Protocol Error")
class HiredisParser(object):
def on_connect(self, connection):
self._sock = connection._sock
self._reader = hiredis.Reader(
protocolError=InvalidResponse,
replyError=ResponseError)
def on_disconnect(self):
self._sock = None
self._reader = None
def read_response(self):
response = self._reader.gets()
while response is False:
try:
buffer = self._sock.recv(4096)
except (socket.error, socket.timeout), e:
raise ConnectionError("Error while reading from socket: %s" % \
(e.args,))
if not buffer:
raise ConnectionError("Socket closed on remote end")
self._reader.feed(buffer)
# if the data received doesn't end with \r\n, then there's more in
# the socket
if not buffer.endswith('\r\n'):
continue
response = self._reader.gets()
return response
try:
import hiredis
DefaultParser = HiredisParser
except ImportError:
DefaultParser = PythonParser
class Connection(object):
"Manages TCP communication to and from a Redis server"
def __init__(self, host='localhost', port=6379, db=0, password=None,
socket_timeout=None, encoding='utf-8',
encoding_errors='strict', parser_class=DefaultParser):
self.host = host
self.port = port
self.db = db
self.password = password
self.socket_timeout = socket_timeout
self.encoding = encoding
self.encoding_errors = encoding_errors
self._sock = None
self._parser = parser_class()
def connect(self):
"Connects to the Redis server if not already connected"
if self._sock:
return
try:
sock = self._connect()
except socket.error, e:
# args for socket.error can either be (errno, "message")
# or just "message"
if len(e.args) == 1:
error_message = "Error connecting to %s:%s. %s." % \
(self.host, self.port, e.args[0])
else:
error_message = "Error %s connecting %s:%s. %s." % \
(e.args[0], self.host, self.port, e.args[1])
raise ConnectionError(error_message)
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 on_connect(self):
"Initialize the connection, authenticate and select a database"
self._parser.on_connect(self)
# if a password is specified, authenticate
if self.password:
self.send_command('AUTH', self.password)
if self.read_response() != 'OK':
raise ConnectionError('Invalid Password')
# if a database is specified, switch to it
if self.db:
self.send_command('SELECT', self.db)
if self.read_response() != 'OK':
raise ConnectionError('Invalid Database')
def disconnect(self):
"Disconnects from the Redis server"
self._parser.on_disconnect()
if self._sock is None:
return
try:
self._sock.close()
except socket.error:
pass
self._sock = None
def _send(self, command):
"Send the command to the socket"
if not self._sock:
self.connect()
try:
self._sock.sendall(command)
except socket.error, e:
if e.args[0] == errno.EPIPE:
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))
def send_packed_command(self, command):
"Send an already packed command to the Redis server"
try:
self._send(command)
except ConnectionError:
# retry the command once in case the socket connection simply
# timed out
self.disconnect()
# if this _send() call fails, then the error will be raised
self._send(command)
def send_command(self, *args):
"Pack and send a command to the Redis server"
self.send_packed_command(self.pack_command(*args))
def read_response(self):
"Read the response from a previously sent command"
response = self._parser.read_response()
if response.__class__ == ResponseError:
raise response
return response
def encode(self, value):
"Return a bytestring representation of the value"
if isinstance(value, unicode):
return value.encode(self.encoding, self.encoding_errors)
return str(value)
def pack_command(self, *args):
"Pack a series of arguments into a value Redis command"
command = ['$%s\r\n%s\r\n' % (len(enc_value), enc_value)
for enc_value in imap(self.encode, args)]
return '*%s\r\n%s' % (len(command), ''.join(command))
class UnixDomainSocketConnection(Connection):
def __init__(self, path='', db=0, password=None,
socket_timeout=None, encoding='utf-8',
encoding_errors='strict', parser_class=DefaultParser):
self.path = path
self.db = db
self.password = password
self.socket_timeout = socket_timeout
self.encoding = encoding
self.encoding_errors = encoding_errors
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
# TODO: add ability to block waiting on a connection to be released
class ConnectionPool(object):
"Generic connection pool"
def __init__(self, connection_class=Connection, max_connections=None,
**connection_kwargs):
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 get_connection(self, command_name, *keys):
"Get a connection from the pool"
try:
connection = self._available_connections.pop()
except IndexError:
connection = self.make_connection()
self._in_use_connections.add(connection)
return connection
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)
def release(self, connection):
"Releases the connection back to the pool"
self._in_use_connections.remove(connection)
self._available_connections.append(connection)
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()
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