#include <db.h>
int
DB_CHANNEL->send_request(DB_CHANNEL *channel, DBT *request,
u_int32_t nrequest, DBT *response,
db_timeout_t timeout, u_int32_t flags);
The DB_CHANNEL->send_request() method
sends a message on the message channel. The message is sent
synchronously; the method blocks waiting for a response before
returning. If a response is not received within the timeout value
configured for this request, this method returns with an error
condition.
If you do not want to block while waiting for a response from a remote site, use the DB_CHANNEL->send_msg() method.
The message sent by this method is received and handled at remote sites using a message dispatch callback, which is configured using the DB_ENV->repmgr_msg_dispatch() method.
The DB_CHANNEL->send_request()
method returns a non-zero error value on failure and 0 on success.
Refers to an array of DBT handles. For more information, see The DBT Handle .
Any flags provided to the DBT handles used in this array are ignored.
Points to a single DBT handle, which is used to
receive the response from the remote site. By default, the
response is expected to be a single-part message. If
there is a possibility that the response could be a
multi-part message, specify DB_MULTIPLE
to this method's flags
parameter.
The response DBT should specify one of the
following flags:
DB_DBT_MALLOC, DB_DBT_REALLOC,
or DB_DBT_USERMEM.
For more information on configuring and using DBTs, see The DBT Handle .
Note that the response DBT can be empty. In this way an application can send an acknowledgement even if there is no other information that needs to be sent.
Configures the amount of time that may elapse while this method waits for a response from the remote site. If this timeout period elapses without a response, this method returns with an error condition.
The timeout value must be specified as an unsigned 32-bit number of microseconds, limiting the maximum timeout to roughly 71 minutes.
A timeout value of 0
indicates that the channel's default timeout value should
be used. This default is configured using the
DB_CHANNEL->set_timeout()
method.
The DB_CHANNEL->send_request()
method may fail and return one of the following non-zero errors:
DB_MULTIPLE was not specified for the
response DBT, but the remote site sent a response
consisting of more than one DBT; or a buffer
supplied using DB_DBT_USERMEM
was not large enough to contain the message response.
A message was sent to a remote site that has not configured a message dispatch callback function. Use the DB_ENV->repmgr_msg_dispatch() method at every site belonging to the replication group to configure a message dispatch callback function.