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from itertools import chain
import os
import socket
import sys
from redis._compat import (b, xrange, imap, byte_to_chr, unicode, bytes, long,
BytesIO, nativestr, basestring)
from redis.exceptions import (
RedisError,
ConnectionError,
ResponseError,
InvalidResponse,
AuthenticationError,
NoScriptError,
ExecAbortError,
)
try:
import hiredis
hiredis_available = True
except ImportError:
hiredis_available = False
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,
'NOSCRIPT': NoScriptError,
'EXECABORT': ExecAbortError,
}
def __init__(self):
self._fp = None
def __del__(self):
try:
self.on_disconnect()
except:
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 is 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)
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")
# *return*, not raise the exception class. if it is meant to be
# raised, it will be at a higher level.
return self.parse_error(response)
# 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
class HiredisParser(object):
"Parser class for connections using Hiredis"
def __init__(self):
if not hiredis_available:
raise RedisError("Hiredis is not installed")
def __del__(self):
try:
self.on_disconnect()
except:
pass
def on_connect(self, connection):
self._sock = connection._sock
kwargs = {
'protocolError': InvalidResponse,
'replyError': ResponseError,
}
if connection.decode_responses:
kwargs['encoding'] = connection.encoding
self._reader = hiredis.Reader(**kwargs)
def on_disconnect(self):
self._sock = None
self._reader = None
def read_response(self):
if not self._reader:
raise ConnectionError("Socket closed on remote end")
response = self._reader.gets()
while response is False:
try:
buffer = self._sock.recv(4096)
except (socket.error, socket.timeout):
e = sys.exc_info()[1]
raise ConnectionError("Error while reading from socket: %s" %
(e.args,))
if not buffer:
raise ConnectionError("Socket closed on remote end")
self._reader.feed(buffer)
# proactively, but not conclusively, check if more data is in the
# buffer. if the data received doesn't end with \n, there's more.
if not buffer.endswith(SYM_LF):
continue
response = self._reader.gets()
return response
if hiredis_available:
DefaultParser = HiredisParser
else:
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', decode_responses=False,
parser_class=DefaultParser):
self.pid = os.getpid()
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.decode_responses = decode_responses
self._sock = None
self._parser = parser_class()
def __del__(self):
try:
self.disconnect()
except:
pass
def connect(self):
"Connects to the Redis 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])
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 nativestr(self.read_response()) != 'OK':
raise AuthenticationError('Invalid Password')
# 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')
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_packed_command(self, command):
"Send an already packed command to the Redis 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:
self.disconnect()
raise
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"
try:
response = self._parser.read_response()
except:
self.disconnect()
raise
if isinstance(response, ResponseError):
raise response
return response
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
def pack_command(self, *args):
"Pack a series of arguments into a value Redis 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, password=None,
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.password = password
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
class ConnectionPool(object):
"Generic connection pool"
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)
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
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._checkpid()
if connection.pid == self.pid:
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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