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 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 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]) 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') 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 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 def send_command(self, *args): "Pack and send a command to the Ledis 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 Exception: 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 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 class ConnectionPool(object): "Generic connection pool" @classmethod 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) 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() 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() def make_connection(self): "Make a fresh connection." connection = self.connection_class(**self.connection_kwargs) self._connections.append(connection) return connection 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 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 def disconnect(self): "Disconnects all connections in the pool." for connection in self._connections: connection.disconnect() 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)