Skip to content

Latest commit

 

History

History
128 lines (102 loc) · 6.11 KB

expiration.md

File metadata and controls

128 lines (102 loc) · 6.11 KB
Raw

Expiration (0x59)

Tells the consumer that the message contains a key expiration. For a general overview on how to trigger these messages, see expiry-opcode-output.md.

The request:

  • Must have extras
  • Must have key
  • Must not have value

Extra looks like:

  Byte/     0       |       1       |       2       |       3       |
     /              |               |               |               |
    |0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|
    +---------------+---------------+---------------+---------------+
   0| by_seqo                                                       |
    |                                                               |
    +---------------+---------------+---------------+---------------+
   8| rev seqno                                                     |
    |                                                               |
    +---------------+---------------+---------------+---------------+
  16| Delete Time                                                   |
    +---------------+-----------------------------------------------*
    Total 20 bytes

The metadata is located after the items key.

The client should not send a reply to this command. The following example shows the breakdown of the message:

  Byte/     0       |       1       |       2       |       3       |
     /              |               |               |               |
    |0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|
    +---------------+---------------+---------------+---------------+
   0| 0x80          | 0x59          | 0x00          | 0x05          |
    +---------------+---------------+---------------+---------------+
   4| 0x12          | 0x00          | 0x02          | 0x10          |
    +---------------+---------------+---------------+---------------+
   8| 0x00          | 0x00          | 0x00          | 0x17          |
    +---------------+---------------+---------------+---------------+
  12| 0x00          | 0x00          | 0x12          | 0x10          |
    +---------------+---------------+---------------+---------------+
  16| 0x00          | 0x00          | 0x00          | 0x00          |
    +---------------+---------------+---------------+---------------+
  20| 0x00          | 0x00          | 0x00          | 0x00          |
    +---------------+---------------+---------------+---------------+
  24| 0x00          | 0x00          | 0x00          | 0x00          |
    +---------------+---------------+---------------+---------------+
  28| 0x00          | 0x00          | 0x00          | 0x05          |
    +---------------+---------------+---------------+---------------+
  32| 0x00          | 0x00          | 0x00          | 0x00          |
    +---------------+---------------+---------------+---------------+
  36| 0x00          | 0x00          | 0x00          | 0x01          |
    +---------------+---------------+---------------+---------------+
  40| 0x00          | 0x00          | 0x00          | 0x00          |
    +---------------+---------------+---------------+---------------+
  44| 0x68 ('h')    | 0x65 ('e')    | 0x6c ('l')    | 0x6c ('l')    |
    +---------------+---------------+---------------+---------------+
  48| 0x6f ('o')    |
    +---------------*
DCP_EXPIRATION command
Field         (offset) (value)
Magic         (0)    : 0x80
Opcode        (1)    : 0x59
Key length    (2,3)  : 0x0005
Extra length  (4)    : 0x12
Data type     (5)    : 0x00
Vbucket       (6,7)  : 0x0210
Total body    (8-11) : 0x00000017
Opaque        (12-15): 0x00001210
CAS           (16-23): 0x0000000000000000
  by seqno    (24-31): 0x0000000000000005
  rev seqno   (32-39): 0x0000000000000001
  delete time (40-43): 0x00000000
Key           (44-48): hello

Returns

This message will not return a response unless an error occurs.

The meaning of datatype

The datatype field of the DCP_EXPIRATION describes the Value payload of the message and not the datatype of the original document. This is important to consider when a producer is opened with any combination of the no value or include xattr flags.

  • Datatype bits
  • DCP without the value or xattr flags - datatype will never contain XATTR, but could be a combination of 0, JSON. If the client has enabled compression, the SNAPPY datatype bit may also be present.
  • DCP_OPEN_NO_VALUE - datatype will always be 0
  • DCP_OPEN_NO_VALUE|DCP_OPEN_INCLUDE_XATTRS - datatype will be 0 or XATTR.
  • DCP_OPEN_INCLUDE_XATTRS - datatype could be many combinations. e.g. 0, XATTR or XATTR|JSON

Delete Time

Receiving expiry opcodes requires 'include delete-times' so that packets sent can use the V2 format.

The delete time field is used to time stamp when the item was deleted. This field is mainly of use to clients building a replica of an active vbucket as the delete time is persisted and used to allow deletions and expirations to remain on disk for a fixed period.

Collections Enabled

If the DCP producer is collection enabled, all keys with be prefixed with the collection-ID of the document encoded as a 32-bit [unsigned LEB128(https://en.wikipedia.org/wiki/LEB128)] value. The key-length field will include the bytes used by the collection-ID.

Errors

PROTOCOL_BINARY_RESPONSE_KEY_ENOENT (0x01)

If a stream does not exist for the vbucket specfied on this connection.

PROTOCOL_BINARY_RESPONSE_EINVAL (0x04)

If data in this packet is malformed or incomplete then this error is returned.

PROTOCOL_BINARY_RESPONSE_ERANGE (0x22)

If the by sequence number is lower than the current by sequence number contained on the consumer. The by sequence number should always be greater than the one the consumer currently has so if the by sequence number in the mutation message is less than or equal to the by sequence number on the consumer this error is returned.

(Disconnect)

If this message is sent to a connection that is not a consumer.