Mutation Tokens

Detailed Description

Mutation Tokens are returned with mutations if LCB_CNTL_FETCH_MUTATION_TOKENS is enabled (off by default). Mutation tokens are largely of internal use, but can be used by N1QL queries and durability requirement polling

Functions
const lcb_MUTATION_TOKEN *	lcb_resp_get_mutation_token (int cbtype, const lcb_RESPBASE *rb)
	Retrieves the mutation token from the response structure. More...
const lcb_MUTATION_TOKEN *	lcb_get_mutation_token (lcb_t instance, const lcb_KEYBUF *kb, lcb_error_t *errp)

Macros
#define	LCB_MUTATION_TOKEN_ID(p)
	Get the vBucket UUID.
#define	LCB_MUTATION_TOKEN_SEQ(p)
	Get the sequence number.
#define	LCB_MUTATION_TOKEN_VB(p)
	Get the vBucket number itself.
#define	LCB_MUTATION_TOKEN_ISVALID(p)
	Whether this mutation token has valid contents.

Function Documentation

const lcb_MUTATION_TOKEN* lcb_resp_get_mutation_token	(	int	cbtype,
		const lcb_RESPBASE *	rb
	)

Retrieves the mutation token from the response structure.

Parameters

cbtype	the type of callback invoked
rb	the pointer to the response

Returns

The embedded mutation token, or NULL if the response does not have a mutation token. This may be either because the command does not support mutation tokens, or because they have been disabled at the connection level.

const lcb_MUTATION_TOKEN* lcb_get_mutation_token	(	lcb_t	instance,
		const lcb_KEYBUF *	kb,
		lcb_error_t *	errp
	)

Stability

Volatile:

Retrieves the last mutation token for a given key. This relies on the LCB_CNTL_DURABILITY_MUTATION_TOKENS option, and will check the instance-level log to determine the latest MUTATION_TOKEN for the given vBucket ID which the key maps to.

Parameters

	instance	the instance
	kb	The buffer representing the key. The type of the buffer (see lcb_KEYBUF::type) may either be LCB_KV_COPY or LCB_KV_VBID
[out]	errp	Set to an error if this function returns NULL

Returns

The mutation token if successful, otherwise NULL.

Getting the latest mutation token for a key:

lcb_KEYBUF kb;
kb.type = LCB_KV_COPY;
kb.contig.bytes = "Hello";
kv.config.nbytes = 5;
mt = lcb_get_mutation_token(instance, &kb, &rc);

Getting the latest mutation token for a vbucket:

lcb_KEYBUF kb;
kv.type = LCB_KV_VBID;
kv.contig.nbytes = 543;
kv.config.bytes = NULL;
mt = lcb_get_mutation_token(instance, &kb, &rc);

Getting the mutation token for each vbucket

size_t ii, nvb;
lcbvb_CONFIG *vbc;
lcb_cntl(instance, LCB_CNTL_GET, LCB_CNTL_VBCONFIG, &vbc);
nvb = vbucket_get_num_vbuckets(vbc);
for (ii = 0; ii < nvb; ii++) {
  lcb_KEYBUF kb;
  const lcb_MUTATION_TOKEN *mt;
  kb.type = LCB_KV_VBID;
  kb.contig.nbytes = ii;
  kb.config.bytes = NULL;
  mt = lcb_get_mutation_token(instance, &kb, &rc);
}

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Data Structure Documentation

struct lcb_MUTATION_TOKEN

Structure representing a synchronization token.

This token may be used for durability operations and N1QL queries. The contents of this structure should be considered opaque, and accessed via the various macros

Data Fields
lcb_U64	uuid_	Use LCB_MUTATION_TOKEN_ID()
lcb_U64	seqno_	Use LCB_MUTATION_TOKEN_SEQ()
lcb_U16	vbid_	Use LCB_MUTATION_TOKEN_VB()