def connect(self):
"Connects to the Redis server if not already connected"
if self._sock:
return
try:
sock = self._connect()
except socket.timeout:
raise TimeoutError("Timeout connecting to server")
except socket.error:
e = sys.exc_info()[1]
raise ConnectionError(self._error_message(e))
self._sock = sock
self._selector = DefaultSelector(sock)
try:
self.on_connect()
except RedisError:
# clean up after any error in on_connect
self.disconnect()
raise
# run any user callbacks. right now the only internal callback
# is for pubsub channel/pattern resubscription
for callback in self._connect_callbacks:
callback(self)
def connect(self):
# TODO 该方法中存在多个try-except块，区别处理不同的异常！！！
"Connects to the Redis server if not already connected"
if self._sock: # TODO 判断是否已经连接上Redis Server
return
try:
sock = self._connect() # TODO 建立1条和Redis Server的TCP链接
except socket.timeout:
raise TimeoutError("Timeout connecting to server")
except socket.error:
e = sys.exc_info()[1]
raise ConnectionError(self._error_message(e))
self._sock = sock # TODO 将链接对象赋给对象属性_sock
self._selector = DefaultSelector(sock) # TODO 异步IO的选择器？？？
try:
self.on_connect() # TODO 校验密码，select DB后链接上Redis Server DB
except RedisError:
# clean up after any error in on_connect
self.disconnect()
raise
# run any user callbacks. right now the only internal callback
# is for pubsub channel/pattern resubscription
for callback in self._connect_callbacks:
callback(self)
def connect(self):
"Connects to the Redis server if not already connected"
if self._sock:
return
try:
sock = self._connect()
except socket.timeout:
raise TimeoutError("Timeout connecting to server")
except socket.error:
e = sys.exc_info()[1]
raise ConnectionError(self._error_message(e))
self._sock = sock
self._selector = DefaultSelector(sock)
try:
self.on_connect()
except RedisError:
# clean up after any error in on_connect
self.disconnect()
raise
# run any user callbacks. right now the only internal callback
# is for pubsub channel/pattern resubscription
for callback in self._connect_callbacks:
callback(self)
class Connection(object):
"Manages TCP communication to and from a Redis server"
description_format = "Connection<host=%(host)s,port=%(port)s,db=%(db)s," \
"client_name=%(client_name)s>"
def __init__(self,
host='localhost',
port=6379,
db=0,
password=None,
socket_timeout=None,
socket_connect_timeout=None,
socket_keepalive=False,
socket_keepalive_options=None,
socket_type=0,
retry_on_timeout=False,
encoding='utf-8',
encoding_errors='strict',
decode_responses=False,
parser_class=DefaultParser,
socket_read_size=65536,
client_name=''):
self.pid = os.getpid()
self.host = host
self.port = int(port)
self.db = db
self.password = password
self.socket_timeout = socket_timeout
self.socket_connect_timeout = socket_connect_timeout or socket_timeout
self.socket_keepalive = socket_keepalive
self.socket_keepalive_options = socket_keepalive_options or {}
self.socket_type = socket_type
self.retry_on_timeout = retry_on_timeout
self.encoder = Encoder(encoding, encoding_errors, decode_responses)
self._sock = None
self._selector = None
self._parser = parser_class(socket_read_size=socket_read_size)
self._client_name = client_name
self._description_args = {
'host': self.host,
'port': self.port,
'db': self.db,
'client_name': self._client_name,
}
self._connect_callbacks = []
self._buffer_cutoff = 6000
def __repr__(self):
return self.description_format % self._description_args
def __del__(self):
try:
self.disconnect()
except Exception:
pass
def register_connect_callback(self, callback):
self._connect_callbacks.append(callback)
def clear_connect_callbacks(self):
self._connect_callbacks = []
def connect(self):
"Connects to the Redis server if not already connected"
if self._sock:
return
try:
sock = self._connect()
except socket.timeout:
raise TimeoutError("Timeout connecting to server")
except socket.error:
e = sys.exc_info()[1]
raise ConnectionError(self._error_message(e))
self._sock = sock
self._selector = DefaultSelector(sock)
try:
self.on_connect()
except RedisError:
# clean up after any error in on_connect
self.disconnect()
raise
# run any user callbacks. right now the only internal callback
# is for pubsub channel/pattern resubscription
for callback in self._connect_callbacks:
callback(self)
def _connect(self):
"Create a TCP socket connection"
# we want to mimic what socket.create_connection does to support
# ipv4/ipv6, but we want to set options prior to calling
# socket.connect()
err = None
for res in socket.getaddrinfo(self.host, self.port, self.socket_type,
socket.SOCK_STREAM):
family, socktype, proto, canonname, socket_address = res
sock = None
try:
sock = socket.socket(family, socktype, proto)
# TCP_NODELAY
sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
# TCP_KEEPALIVE
if self.socket_keepalive:
sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
for k, v in iteritems(self.socket_keepalive_options):
sock.setsockopt(socket.IPPROTO_TCP, k, v)
# set the socket_connect_timeout before we connect
sock.settimeout(self.socket_connect_timeout)
# connect
sock.connect(socket_address)
# set the socket_timeout now that we're connected
sock.settimeout(self.socket_timeout)
return sock
except socket.error as _:
err = _
if sock is not None:
sock.close()
if err is not None:
raise err
raise socket.error("socket.getaddrinfo returned an empty list")
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 to %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 self._client_name:
self.send_command('CLIENT', 'SETNAME', self._client_name)
if nativestr(self.read_response()) != 'OK':
raise ConnectionError('Error setting client name')
# 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
if self._selector is not None:
self._selector.close()
self._selector = None
try:
if os.getpid() == self.pid:
self._sock.shutdown(socket.SHUT_RDWR)
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:
if isinstance(command, str):
command = [command]
for item in command:
self._sock.sendall(item)
except socket.timeout:
self.disconnect()
raise TimeoutError("Timeout writing to socket")
except socket.error:
e = sys.exc_info()[1]
self.disconnect()
if len(e.args) == 1:
errno, errmsg = 'UNKNOWN', e.args[0]
else:
errno = e.args[0]
errmsg = e.args[1]
raise ConnectionError("Error %s while writing to socket. %s." %
(errno, errmsg))
except: # noqa: E722
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 can_read(self, timeout=0):
"Poll the socket to see if there's data that can be read."
sock = self._sock
if not sock:
self.connect()
sock = self._sock
return self._parser.can_read() or self._selector.can_read(timeout)
def is_ready_for_command(self):
"Check if the connection is ready for a command"
return self._selector.is_ready_for_command()
def read_response(self):
"Read the response from a previously sent command"
try:
response = self._parser.read_response()
except socket.timeout:
self.disconnect()
raise TimeoutError("Timeout reading from %s:%s" %
(self.host, self.port))
except socket.error:
self.disconnect()
e = sys.exc_info()[1]
raise ConnectionError("Error while reading from %s:%s : %s" %
(self.host, self.port, e.args))
except: # noqa: E722
self.disconnect()
raise
if isinstance(response, ResponseError):
raise response
return response
def pack_command(self, *args):
"Pack a series of arguments into the Redis protocol"
output = []
# the client might have included 1 or more literal arguments in
# the command name, e.g., 'CONFIG GET'. The Redis server expects these
# arguments to be sent separately, so split the first argument
# manually. All of these arguements get wrapped in the Token class
# to prevent them from being encoded.
command = args[0]
if ' ' in command:
args = tuple(Token.get_token(s)
for s in command.split()) + args[1:]
else:
args = (Token.get_token(command), ) + args[1:]
buff = SYM_EMPTY.join((SYM_STAR, str(len(args)).encode(), SYM_CRLF))
buffer_cutoff = self._buffer_cutoff
for arg in imap(self.encoder.encode, args):
# to avoid large string mallocs, chunk the command into the
# output list if we're sending large values
if len(buff) > buffer_cutoff or len(arg) > buffer_cutoff:
buff = SYM_EMPTY.join(
(buff, SYM_DOLLAR, str(len(arg)).encode(), SYM_CRLF))
output.append(buff)
output.append(arg)
buff = SYM_CRLF
else:
buff = SYM_EMPTY.join(
(buff, SYM_DOLLAR, str(len(arg)).encode(), SYM_CRLF, arg,
SYM_CRLF))
output.append(buff)
return output
def pack_commands(self, commands):
"Pack multiple commands into the Redis protocol"
output = []
pieces = []
buffer_length = 0
buffer_cutoff = self._buffer_cutoff
for cmd in commands:
for chunk in self.pack_command(*cmd):
chunklen = len(chunk)
if buffer_length > buffer_cutoff or chunklen > buffer_cutoff:
output.append(SYM_EMPTY.join(pieces))
buffer_length = 0
pieces = []
if chunklen > self._buffer_cutoff:
output.append(chunk)
else:
pieces.append(chunk)
buffer_length += chunklen
if pieces:
output.append(SYM_EMPTY.join(pieces))
return output
class Connection(object):
"Manages TCP communication to and from a Redis server"
description_format = "Connection<host=%(host)s,port=%(port)s,db=%(db)s>"
def __init__(self, host='localhost', port=6379, db=0, password=None,
socket_timeout=None, socket_connect_timeout=None,
socket_keepalive=False, socket_keepalive_options=None,
socket_type=0, retry_on_timeout=False, encoding='utf-8',
encoding_errors='strict', decode_responses=False,
parser_class=DefaultParser, socket_read_size=65536):
self.pid = os.getpid()
self.host = host
self.port = int(port)
self.db = db
self.password = password
self.socket_timeout = socket_timeout
self.socket_connect_timeout = socket_connect_timeout or socket_timeout
self.socket_keepalive = socket_keepalive
self.socket_keepalive_options = socket_keepalive_options or {}
self.socket_type = socket_type
self.retry_on_timeout = retry_on_timeout
self.encoder = Encoder(encoding, encoding_errors, decode_responses)
self._sock = None
self._selector = None
self._parser = parser_class(socket_read_size=socket_read_size)
self._description_args = {
'host': self.host,
'port': self.port,
'db': self.db,
}
self._connect_callbacks = []
self._buffer_cutoff = 6000
def __repr__(self):
return self.description_format % self._description_args
def __del__(self):
try:
self.disconnect()
except Exception:
pass
def register_connect_callback(self, callback):
self._connect_callbacks.append(callback)
def clear_connect_callbacks(self):
self._connect_callbacks = []
def connect(self):
"Connects to the Redis server if not already connected"
if self._sock:
return
try:
sock = self._connect()
except socket.timeout:
raise TimeoutError("Timeout connecting to server")
except socket.error:
e = sys.exc_info()[1]
raise ConnectionError(self._error_message(e))
self._sock = sock
self._selector = DefaultSelector(sock)
try:
self.on_connect()
except RedisError:
# clean up after any error in on_connect
self.disconnect()
raise
# run any user callbacks. right now the only internal callback
# is for pubsub channel/pattern resubscription
for callback in self._connect_callbacks:
callback(self)
def _connect(self):
"Create a TCP socket connection"
# we want to mimic what socket.create_connection does to support
# ipv4/ipv6, but we want to set options prior to calling
# socket.connect()
err = None
for res in socket.getaddrinfo(self.host, self.port, self.socket_type,
socket.SOCK_STREAM):
family, socktype, proto, canonname, socket_address = res
sock = None
try:
sock = socket.socket(family, socktype, proto)
# TCP_NODELAY
sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
# TCP_KEEPALIVE
if self.socket_keepalive:
sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
for k, v in iteritems(self.socket_keepalive_options):
sock.setsockopt(socket.IPPROTO_TCP, k, v)
# set the socket_connect_timeout before we connect
sock.settimeout(self.socket_connect_timeout)
# connect
sock.connect(socket_address)
# set the socket_timeout now that we're connected
sock.settimeout(self.socket_timeout)
return sock
except socket.error as _:
err = _
if sock is not None:
sock.close()
if err is not None:
raise err
raise socket.error("socket.getaddrinfo returned an empty list")
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 to %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
if self._selector is not None:
self._selector.close()
self._selector = None
try:
if os.getpid() == self.pid:
self._sock.shutdown(socket.SHUT_RDWR)
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:
if isinstance(command, str):
command = [command]
for item in command:
self._sock.sendall(item)
except socket.timeout:
self.disconnect()
raise TimeoutError("Timeout writing to socket")
except socket.error:
e = sys.exc_info()[1]
self.disconnect()
if len(e.args) == 1:
errno, errmsg = 'UNKNOWN', e.args[0]
else:
errno = e.args[0]
errmsg = e.args[1]
raise ConnectionError("Error %s while writing to socket. %s." %
(errno, errmsg))
except: # noqa: E722
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 can_read(self, timeout=0):
"Poll the socket to see if there's data that can be read."
sock = self._sock
if not sock:
self.connect()
sock = self._sock
return self._parser.can_read() or self._selector.can_read(timeout)
def is_ready_for_command(self):
"Check if the connection is ready for a command"
return self._selector.is_ready_for_command()
def read_response(self):
"Read the response from a previously sent command"
try:
response = self._parser.read_response()
except: # noqa: E722
self.disconnect()
raise
if isinstance(response, ResponseError):
raise response
return response
def pack_command(self, *args):
"Pack a series of arguments into the Redis protocol"
output = []
# the client might have included 1 or more literal arguments in
# the command name, e.g., 'CONFIG GET'. The Redis server expects these
# arguments to be sent separately, so split the first argument
# manually. All of these arguements get wrapped in the Token class
# to prevent them from being encoded.
command = args[0]
if ' ' in command:
args = tuple(Token.get_token(s)
for s in command.split()) + args[1:]
else:
args = (Token.get_token(command),) + args[1:]
buff = SYM_EMPTY.join((SYM_STAR, str(len(args)).encode(), SYM_CRLF))
buffer_cutoff = self._buffer_cutoff
for arg in imap(self.encoder.encode, args):
# to avoid large string mallocs, chunk the command into the
# output list if we're sending large values
if len(buff) > buffer_cutoff or len(arg) > buffer_cutoff:
buff = SYM_EMPTY.join(
(buff, SYM_DOLLAR, str(len(arg)).encode(), SYM_CRLF))
output.append(buff)
output.append(arg)
buff = SYM_CRLF
else:
buff = SYM_EMPTY.join(
(buff, SYM_DOLLAR, str(len(arg)).encode(),
SYM_CRLF, arg, SYM_CRLF))
output.append(buff)
return output
def pack_commands(self, commands):
"Pack multiple commands into the Redis protocol"
output = []
pieces = []
buffer_length = 0
buffer_cutoff = self._buffer_cutoff
for cmd in commands:
for chunk in self.pack_command(*cmd):
chunklen = len(chunk)
if buffer_length > buffer_cutoff or chunklen > buffer_cutoff:
output.append(SYM_EMPTY.join(pieces))
buffer_length = 0
pieces = []
if chunklen > self._buffer_cutoff:
output.append(chunk)
else:
pieces.append(chunk)
buffer_length += chunklen
if pieces:
output.append(SYM_EMPTY.join(pieces))
return output
class Connection(object):
"Manages TCP communication to and from a Redis server"
# TODO 管理客户端与Redis服务器之间的TCP通信
description_format = "Connection<host=%(host)s,port=%(port)s,db=%(db)s>"
def __init__(self,
host='localhost',
port=6379,
db=0,
password=None,
socket_timeout=None,
socket_connect_timeout=None,
socket_keepalive=False,
socket_keepalive_options=None,
socket_type=0,
retry_on_timeout=False,
encoding='utf-8',
encoding_errors='strict',
decode_responses=False,
parser_class=DefaultParser,
socket_read_size=65536): # TODO 默认读取的报文长度为65536！！！
self.pid = os.getpid()
self.host = host
self.port = int(port)
self.db = db
self.password = password
self.socket_timeout = socket_timeout
self.socket_connect_timeout = socket_connect_timeout or socket_timeout
self.socket_keepalive = socket_keepalive
self.socket_keepalive_options = socket_keepalive_options or {}
self.socket_type = socket_type
self.retry_on_timeout = retry_on_timeout
self.encoder = Encoder(encoding, encoding_errors, decode_responses)
self._sock = None
self._parser = parser_class(
socket_read_size=socket_read_size) # TODO 初始化回复的解析class
self._description_args = {
'host': self.host,
'port': self.port,
'db': self.db,
}
self._connect_callbacks = []
self._buffer_cutoff = 6000 # TODO 发送给Redis Server端的单个数据包的最大长度
def __repr__(self):
return self.description_format % self._description_args
def __del__(self):
try:
self.disconnect()
except Exception:
pass
def register_connect_callback(self, callback):
self._connect_callbacks.append(callback)
def clear_connect_callbacks(self):
self._connect_callbacks = []
def connect(self):
# TODO 该方法中存在多个try-except块，区别处理不同的异常！！！
"Connects to the Redis server if not already connected"
if self._sock: # TODO 判断是否已经连接上Redis Server
return
try:
sock = self._connect() # TODO 建立1条和Redis Server的TCP链接
except socket.timeout:
raise TimeoutError("Timeout connecting to server")
except socket.error:
e = sys.exc_info()[1]
raise ConnectionError(self._error_message(e))
self._sock = sock # TODO 将链接对象赋给对象属性_sock
self._selector = DefaultSelector(sock) # TODO 异步IO的选择器？？？
try:
self.on_connect() # TODO 校验密码，select DB后链接上Redis Server DB
except RedisError:
# clean up after any error in on_connect
self.disconnect()
raise
# run any user callbacks. right now the only internal callback
# is for pubsub channel/pattern resubscription
for callback in self._connect_callbacks:
callback(self)
def _connect(self):
"Create a TCP socket connection"
# TODO 创建一个与Redis Server的TCP socket链接
# we want to mimic what socket.create_connection does to support
# ipv4/ipv6, but we want to set options prior to calling
# socket.connect()
# TODO 使用socket库创建链接
err = None
for res in socket.getaddrinfo(self.host, self.port, self.socket_type,
socket.SOCK_STREAM):
family, socktype, proto, canonname, socket_address = res
sock = None
try:
sock = socket.socket(family, socktype, proto)
# TCP_NODELAY
sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
# TCP_KEEPALIVE
if self.socket_keepalive:
sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
for k, v in iteritems(self.socket_keepalive_options):
sock.setsockopt(socket.IPPROTO_TCP, k, v)
# TODO * In blocking mode, operations block until complete or the system returns an error (such as connection timed out).
# TODO * In non-blocking mode, operations fail (with an error that is unfortunately system-dependent) if they cannot be completed immediately: functions from the select can be used to know when and whether a socket is available for reading or writing.
# TODO * In timeout mode, operations fail if they cannot be completed within the timeout specified for the socket (they raise a timeout exception) or if the system returns an error.
# 在阻塞模式下，操作阻塞到完成或者系统返回一个错误(例如链接超时)
# 在非阻塞模式，如果操作不能立即完成，则会返回失败(抛出依赖于操作系统的错误)。select中的函数可用于了解套接字何时以及是否可用于读取或写入。
# 在超时模式下，如果在指定的时间内操作(特别对于socket而言)未完成或系统返回了错误，则会认为失败。
# set the socket_connect_timeout before we connect
sock.settimeout(self.socket_connect_timeout)
# TODO Set a timeout on blocking socket operations.
# 为阻塞中的socket操作设置超时时长
# The value argument can be a nonnegative floating point number expressing seconds, or None.
# If a non-zero value is given, subsequent socket operations will raise a timeout exception if the timeout period value has elapsed before the operation has completed.
# If zero is given, the socket is put in non-blocking mode. If None is given, the socket is put in blocking mode.
# TODO 参数值可以为非负浮点数表示的秒或者None。如果是非0值，前面的操作时长已经达到超时值后，后面请求的操作将抛出timeout异常。
# 如果超时时长设置为0，socket将变为非阻塞模式。如果设置为None,socket就时阻塞模式。
# connect
sock.connect(socket_address)
# set the socket_timeout now that we're connected
sock.settimeout(self.socket_timeout)
return sock
except socket.error as _:
err = _
if sock is not None:
sock.close()
if err is not None:
raise err
raise socket.error("socket.getaddrinfo returned an empty list")
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 to %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"
# TODO 初始化链接：鉴权和选择一个DB
self._parser.on_connect(self) # TODO 创建response的解析类对象
# 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:
if os.getpid() == self.pid:
self._sock.shutdown(socket.SHUT_RDWR)
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"
# TODO 将封装好的数据包发送到Redis Server，如果发送出现错误，将会断开本条链路！！！
if not self._sock:
self.connect()
try:
if isinstance(command, str):
command = [command]
for item in command: # TODO 逐个发送
self._sock.sendall(item)
except socket.timeout:
self.disconnect()
raise TimeoutError("Timeout writing to socket")
except socket.error:
e = sys.exc_info()[1]
self.disconnect()
if len(e.args) == 1:
errno, errmsg = 'UNKNOWN', e.args[0]
else:
errno = e.args[0]
errmsg = e.args[1]
raise ConnectionError("Error %s while writing to socket. %s." %
(errno, errmsg))
except: # noqa: E722
self.disconnect()
raise
def send_command(self, *args):
"Pack and send a command to the Redis server"
# TODO 先封包命令和参数，再发送封装好的数据包
self.send_packed_command(self.pack_command(*args))
def can_read(self, timeout=0):
"Poll the socket to see if there's data that can be read."
sock = self._sock
if not sock:
self.connect()
sock = self._sock
return self._parser.can_read() or self._selector.can_read(timeout)
def is_ready_for_command(self):
"Check if the connection is ready for a command"
return self._selector.is_ready_for_command()
def read_response(self):
"Read the response from a previously sent command"
try:
response = self._parser.read_response()
except: # noqa: E722
self.disconnect()
raise
if isinstance(response, ResponseError):
raise response
return response
def pack_command(self, *args):
"Pack a series of arguments into the Redis protocol"
# TODO 将入参包装成为Redis协议数据放到output中返回
output = []
# the client might have included 1 or more literal arguments in
# the command name, e.g., 'CONFIG GET'. The Redis server expects these
# arguments to be sent separately, so split the first argument
# manually. All of these arguements get wrapped in the Token class
# to prevent them from being encoded.
command = args[0]
if ' ' in command:
args = tuple(Token.get_token(s)
for s in command.split()) + args[1:]
else:
args = (Token.get_token(command), ) + args[1:]
buff = SYM_EMPTY.join((SYM_STAR, str(len(args)).encode(),
SYM_CRLF)) # TODO bytes类型表示的args的长度
buffer_cutoff = self._buffer_cutoff # TODO 获取单个数据包的最大长度
for arg in imap(self.encoder.encode, args):
# to avoid large string mallocs, chunk the command into the
# output list if we're sending large values
if len(buff) > buffer_cutoff or len(arg) > buffer_cutoff:
buff = SYM_EMPTY.join(
(buff, SYM_DOLLAR, str(len(arg)).encode(), SYM_CRLF))
output.append(buff) # TODO 数据过长，分成2个部分
output.append(arg)
buff = SYM_CRLF
else:
buff = SYM_EMPTY.join(
(buff, SYM_DOLLAR, str(len(arg)).encode(), SYM_CRLF, arg,
SYM_CRLF))
output.append(buff)
return output
def pack_commands(self, commands):
"Pack multiple commands into the Redis protocol"
output = []
pieces = []
buffer_length = 0
buffer_cutoff = self._buffer_cutoff
for cmd in commands:
for chunk in self.pack_command(*cmd):
chunklen = len(chunk)
if buffer_length > buffer_cutoff or chunklen > buffer_cutoff:
output.append(SYM_EMPTY.join(pieces))
buffer_length = 0
pieces = []
if chunklen > self._buffer_cutoff:
output.append(chunk)
else:
pieces.append(chunk)
buffer_length += chunklen
if pieces:
output.append(SYM_EMPTY.join(pieces))
return output
