Maapi_query_result_count

[leen]

Hi,

Where can i get the the document of this function maapi_query_result_count?

Sometimes this function return -1, and the error message is "Unexpected data on socket! ", I don’t know what happened.

And by the way what the exact value of chunk_size parameter should be of function maapi_query_start(), I set it to 1000 as the example code shows, but I don’t know the proper value.

[cohult]

Hi,

See for example these previous posts:

Operational data subscription issue

A good rule to follow is using “one thread per socket”. No sharing of sockets between threads. From ConfD UG chapter The Protocol and a Library Threads Discussion: ConfD API functions are thread-safe as such, but multiple threads using them with the same socket will have unpredictable results, just as multiple threads using the read() and write() system calls on the same file descriptor in general will. In the ConfD case, one thread may end up getting the response to a request from another, o…

Cdb_sync_subscription_socket return Unexpected data on socket

The reason is likely that the application is mixing up its CDB and/or MAAPI sockets - e.g. two threads trying to use the same socket at the same time. What it means is that a CDB or MAAPI API function makes a request to ConfD, and gets a response back from ConfD that doesn’t match the request. The examples.confd/intro/9-c_threads/ example shows how one should handle these sockets when using multiple threads.

[leen]

@cohult Thanks for the reply, I’ll check my threads.

By the way , would you please provide me the explaination of maapi_query_result_count?

[mvf]

The expression provided as argument to maapi_query_start must evaluate to a node set; maapi_query_result_count returns CONFD_ERR or size of this node set.

[leen]

As you mentioned this api:

int maapi_query_start(int sock, int thandle, const char *expr,
const char *context_node, int chunk_size, 
int initial_offset, enum
confd_query_result_type result_as, int nselect, const char *select[],
int nsort, const char *sort[]);

and User Guide says:

chunk_size How many results to return at a time. If set to 0 a default number will be used.

so, if I have list that has more than 2000 instances inside, and I set chunk_size = 1000, what does maapi_query_result_count returns? 2000 or 1000?

[mvf]

It returns the size of the whole node set, i.e. 2000 in your case. It is useful right after maapi_start_query, it tells you what you should expect. You do not need to call any API function to know how large a particular chunk is - the structure confd_query_result contains field nresults that indicates it.