312 lines
8.6 KiB
Python
Executable File
312 lines
8.6 KiB
Python
Executable File
#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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import asyncio
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import socket
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import time
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import random
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import traceback
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import typing
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class MemcacheEntry:
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def __init__(self, flags: bytes, exptime: bytes, data: bytes, cas: bytes):
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self.flags: int = self._flags(flags)
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self.data: bytes = data
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self.cas: bytes = cas
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self.expire: typing.Optional[float] = self._ttl(exptime)
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@staticmethod
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def _flags(flags: bytes) -> int:
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v = int(flags)
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if v < 0 or v >= 2**32: raise ValueError('flags not an unsigned 32-bit integer')
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return v
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@staticmethod
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def _ttl(value: bytes) -> typing.Optional[float]:
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v = int(value)
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if v < 0: raise ValueError('exptime not an unsigned integer')
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if v > 0 and v < 365*24*3600:
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return v + time.time()
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else:
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return None
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def setExptime(self, exptime: bytes):
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self.expire = self._ttl(exptime)
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def flush(self, exptime: float):
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# make sure entry expires at `exptime` (or before)
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if self.expire is None or self.expire > exptime:
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self.expire = exptime
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def expired(self):
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return self.expire != None and self.expire < time.time()
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class MemcacheDB:
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def __init__(self):
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self.d = dict()
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self._cas = random.randint(0, 2**64-1)
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@staticmethod
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def _uint64value(str):
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v = int(str)
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if v < 0 or v >= 2**64: raise ValueError('not an unsigned 64-bit integer')
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return v
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def _next_cas(self) -> bytes:
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cas = self._cas
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self._cas = (cas + 1) % 2**64
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return b'%d' % cas
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def get(self, key: bytes):
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if not key in self.d: return None
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entry = self.d[key]
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if entry.expired():
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self.d.pop(key)
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return None
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return entry
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def set(self, key: bytes, flags: bytes, exptime: bytes, data: bytes):
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self.d[key] = MemcacheEntry(flags, exptime, data, self._next_cas())
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return b"STORED"
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def add(self, key: bytes, flags: bytes, exptime: bytes, data: bytes):
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if None != self.get(key): return b"NOT_STORED"
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self.d[key] = MemcacheEntry(flags, exptime, data, self._next_cas())
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return b"STORED"
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def replace(self, key: bytes, flags: bytes, exptime: bytes, data: bytes):
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if None == self.get(key): return b"NOT_STORED"
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self.d[key] = MemcacheEntry(flags, exptime, data, self._next_cas())
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return b"STORED"
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def append(self, key: bytes, data: bytes):
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entry = self.get(key)
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if None == entry: return b"NOT_FOUND"
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entry.data += data
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entry.cas = self._next_cas()
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return b"STORED"
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def prepend(self, key: bytes, data: bytes):
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entry = self.get(key)
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if None == entry: return b"NOT_FOUND"
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entry.data = data + entry.data
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entry.cas = self._next_cas()
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return b"STORED"
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def cas(self, key: bytes, flags: bytes, exptime: bytes, cas: bytes, data: bytes):
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entry = self.get(key)
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if None == entry: return b"NOT_FOUND"
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if entry.cas != cas: return b"EXISTS"
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self.d[key] = MemcacheEntry(flags, exptime, data, self._next_cas())
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return b"STORED"
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def delete(self, key: bytes):
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entry = self.get(key)
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if None == entry: return b"NOT_FOUND"
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self.d.pop(key)
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return b"DELETED"
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def incr(self, key: bytes, value: bytes):
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try:
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value = self._uint64value(value)
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except ValueError as e:
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return b"CLIENT_ERROR %s" % str(e).encode('utf-8')
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entry = self.get(key)
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if None == entry: return b"NOT_FOUND"
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try:
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v = self._uint64value(entry.data)
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v = (v + value) % 2**64
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entry.data = str(v)
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entry.cas = self._next_cas()
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except ValueError as e:
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return b"SERVER_ERROR %s" % str(e).encode('utf-8')
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return entry.data
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def decr(self, key: bytes, value: bytes):
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try:
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value = self._uint64value(value)
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except ValueError as e:
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return b"CLIENT_ERROR %s" % str(e).encode('utf-8')
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entry = self.get(key)
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if None == entry: return b"NOT_FOUND"
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try:
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v = self._uint64value(entry.data)
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v = v - value
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if v < 0: v = 0
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entry.data = str(v)
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entry.cas = self._next_cas()
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except ValueError as e:
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return b"SERVER_ERROR %s" % str(e).encode('utf-8')
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return entry.data
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def touch(self, key: bytes, exptime: bytes):
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entry = self.get(key)
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if None == entry: return b"NOT_FOUND"
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entry.setExptime(exptime)
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return b"TOUCHED"
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def stats(self):
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return []
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def flush_all(self, exptime: typing.Optional[bytes] = None):
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if exptime is None:
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self.d = dict()
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else:
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expire_at = MemcacheEntry._ttl(exptime) or time.time()
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for key in self.d.keys():
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entry = self.get(key)
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if entry != None: entry.flush(expire_at)
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return b"OK"
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def version(self):
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return b"VERSION python memcached stub 0.1"
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def verbosity(self, level: bytes):
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return b"OK"
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class MemcachedHandler:
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def __init__(self, *, reader: asyncio.StreamReader, writer: asyncio.StreamWriter, db: MemcacheDB):
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self.reader = reader
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self.writer = writer
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self.db = db
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self.data = b''
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self.want_binary = None
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self.closed = False
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def _server_error(self, msg: str):
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self.writer.write(b'SERVER_ERROR %s\r\n' % msg.encode('utf-8'))
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self.data = b''
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self.closed = True
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def _client_error(self, msg: str):
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self.writer.write(b'CLIENT_ERROR %s\r\n' % msg.encode('utf-8'))
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self.data = b''
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self.closed = True
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def _error(self):
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self.writer.write(b'ERROR\r\n')
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self.data = b''
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self.closed = True
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def _handle_binary(self, b):
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args = self.args
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cmd = self.cmd
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noreply = self.noreply
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self.cmd = self.args = self.noreply = None
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r = (getattr(self.db, cmd))(*args, b)
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if not noreply: self.writer.write(b'%s\r\n' % r)
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def _handle_line(self, line):
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args = line.split()
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if len(args) == 0: return self._client_error("empty command")
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cmd = args[0].decode('ascii')
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args = args[1:]
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noreply = False
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if args[-1] == b"noreply":
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args.pop()
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noreply = True
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if cmd in ['set', 'add', 'replace', 'append', 'prepend']:
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if len(args) != 4: return self._client_error("wrong number %i of arguments for command" % 4)
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self.want_binary = int(args[3])
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if self.want_binary < 0: return self._client_error("negative bytes length")
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self.args = args[:3]
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self.cmd = cmd
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self.noreply = noreply
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elif cmd == 'cas':
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if len(args) != 5: return self._client_error("wrong number %i of arguments for command" % 5)
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self.want_binary = args[3]
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args = args[:3] + args[4:]
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self.cmd = cmd
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self.noreply = noreply
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elif cmd == 'get':
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for key in args:
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entry = self.db.get(key)
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if entry != None:
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self.writer.write(b'VALUE %s %d %d\r\n%s\r\n' % (key, entry.flags, len(entry.data), entry.data))
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self.writer.write(b'END\r\n')
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elif cmd == 'gets':
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for key in args:
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entry = self.db.get(key)
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if entry != None:
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self.writer.write(b'VALUE %s %d %d %d\r\n%s\r\n' % (key, entry.flags, len(entry.data), entry.cas, entry.data))
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self.writer.write(b'END\r\n')
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elif cmd == 'stats':
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for (name, value) in self.db.stats():
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self.writer.write(b'STAT %s %s\r\n' % (name, value))
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self.writer.write(b'END\r\n')
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elif cmd in ['delete', 'incr', 'decr', 'touch', 'flush_all', 'version', 'verbosity']:
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r = (getattr(self.db, cmd))(*args)
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if not noreply: self.writer.write(r + b'\r\n')
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else:
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return self._error()
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def _handle_data(self):
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while len(self.data) > 0:
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if self.want_binary != None:
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if len(self.data) >= self.want_binary + 2:
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b = self.data[:self.want_binary]
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if self.data[self.want_binary:self.want_binary+2] != b'\r\n':
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return self._client_error("wrong termination of binary data")
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self.data = self.data[self.want_binary+2:]
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self._handle_binary(b)
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else:
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return # wait for more data
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else:
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pos = self.data.find(b'\r\n')
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if pos < 0:
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if len(self.data) > 512:
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return self._client_error("command too long")
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return # wait for more data
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l = self.data[:pos]
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self.data = self.data[pos+2:]
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self._handle_line(l)
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async def handle(self):
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while not self.closed:
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await self.writer.drain()
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next_buf = await self.reader.read(8192)
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if len(next_buf) == 0:
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# received EOF, close immediately.
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self.writer.close()
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return
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self.data += next_buf
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try:
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self._handle_data()
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except TypeError as e:
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self._client_error("wrong number of arguments for command: %s" % e)
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print(traceback.format_exc())
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# close
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await self.writer.drain()
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self.writer.close()
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await self.writer.wait_closed()
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async def main():
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sock = socket.socket(fileno=0)
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if sock.type == socket.AF_UNIX:
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start_server = asyncio.start_unix_server
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else:
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start_server = asyncio.start_server
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db = MemcacheDB()
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async def handle_memcache_client(reader, writer):
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print(f"Memcached: Incoming connection", flush=True)
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await MemcachedHandler(reader=reader, writer=writer, db=db).handle()
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server = await start_server(handle_memcache_client, sock=sock, start_serving=False)
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addr = server.sockets[0].getsockname()
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print(f'Serving on {addr}', flush=True)
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async with server:
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await server.serve_forever()
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try:
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asyncio.run(main())
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except KeyboardInterrupt:
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pass
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