一个flag引发的惨案(memcached)

def add(self, key, value, expire=0, noreply=None, flags=None):
    """
    The memcached "add" command.

    Args:
        key: str, see class docs for details.
        value: str, see class docs for details.
        expire: optional int, number of seconds until the item is expired
                from the cache, or zero for no expiry (the default).
        noreply: optional bool, True to not wait for the reply (defaults to
                self.default_noreply).
        flags: optional int, arbitrary bit field used for server-specific
                flags

    Returns:
        If noreply is True, the return value is always True. Otherwise the
        return value is True if the value was stored, and False if it was
        not (because the key already existed).
    """
    if noreply is None:
        noreply = self.default_noreply
    return self._store_cmd(b'add', {key: value}, expire, noreply,
                            flags=flags)[key]

String cmd = "get " + key + "\r\n";
log.debug("++++ memcache get command: " + cmd);
sock.write(cmd.getBytes());
sock.flush();
Map<String, Object> hm = new HashMap();
this.loadItems(sock, hm, asString);
log.debug("++++ memcache: got back " + hm.size() + " results");
sock.close();
return hm.get(key);

# this.loadItems(sock, hm, asString); 方法

if ((flag & 2) != 0) {
  ....
}

if ((flag & 8) == 0) {
  ....
}

if ((flag & 2) != 0) {
    try {
        GZIPInputStream gzi = new GZIPInputStream(new ByteArrayInputStream(buf));
        ByteArrayOutputStream bos = new ByteArrayOutputStream(buf.length);
        byte[] tmp = new byte[2048];

        int count;
        while((count = gzi.read(tmp)) != -1) {
            bos.write(tmp, 0, count);
        }

        buf = bos.toByteArray();
        gzi.close();
    } catch (IOException var17) {
        if (this.errorHandler != null) {
            this.errorHandler.handleErrorOnGet(this, var17, key);
        }

        log.error("++++ IOException thrown while trying to uncompress input stream for key: " + key);
        log.error(var17.getMessage(), var17);
        throw new NestedIOException("++++ IOException thrown while trying to uncompress input stream for key: " + key, var17);
    }
}

Object o;
if ((flag & 8) == 0) {
    if (!this.primitiveAsString && !asString) {
        try {
            o = NativeHandler.decode(buf);
        } catch (Exception var15) {
            if (this.errorHandler != null) {
                this.errorHandler.handleErrorOnGet(this, var15, key);
            }

            log.error("++++ Exception thrown while trying to deserialize for key: " + key, var15);
            throw new NestedIOException(var15);
        }
    } else {
        log.info("++++ retrieving object and stuffing into a string.");
        o = new String(buf, this.defaultEncoding);
    }
} else {
    ContextObjectInputStream ois = new ContextObjectInputStream(new ByteArrayInputStream(buf), this.classLoader);

    try {
        o = ois.readObject();
        log.info("++++ deserializing " + o.getClass());
    } catch (ClassNotFoundException var16) {
        if (this.errorHandler != null) {
            this.errorHandler.handleErrorOnGet(this, var16, key);
        }

        log.error("++++ ClassNotFoundException thrown while trying to deserialize for key: " + key, var16);
        throw new NestedIOException("+++ failed while trying to deserialize for key: " + key, var16);
    }
}

public static Object decode(byte[] b) throws Exception {
    if (b.length < 1) {
        return null;
    } else if (b[0] == 2) {
        return decodeBoolean(b);
    } else if (b[0] == 3) {
        return decodeInteger(b);
    } else if (b[0] == 6) {
        return decodeString(b);
    } else if (b[0] == 5) {
        return decodeCharacter(b);
    } else if (b[0] == 1) {
        return decodeByte(b);
    } else if (b[0] == 7) {
        return decodeStringBuffer(b);
    } else if (b[0] == 9) {
        return decodeShort(b);
    } else if (b[0] == 4) {
        return decodeLong(b);
    } else if (b[0] == 10) {
        return decodeDouble(b);
    } else if (b[0] == 8) {
        return decodeFloat(b);
    } else {
        return b[0] == 11 ? decodeDate(b) : null;
    }
}

b"".join([bytes([6]), str.encode(data)])