#include <db_cxx.h>
int
DbEnv::rep_process_message(Dbt *control, Dbt *rec, int envid,
DbLsn *ret_lsnp)
The DbEnv::rep_process_message() method processes an incoming
replication message sent by a member of the replication group to the
local database environment.
The DbEnv::rep_process_message() method is not called by most
replication applications. It should only be called by Base API applications
implementing their own network transport layer, explicitly holding
replication group elections and handling replication messages outside
of the Replication Manager framework.
For implementation reasons, all incoming replication messages must be processed using the same DbEnv handle. It is not required that a single thread of control process all messages, only that all threads of control processing messages use the same handle.
Before calling this method, the enclosing database environment must already have been opened by calling the DbEnv::open() method and must already have been configured to send replication messages by calling the DbEnv::rep_set_transport() method.
The DbEnv::rep_process_message() method has additional return
values:
The DbEnv::rep_process_message() method will return
DB_REP_DUPMASTER if the replication group has more than one
master. The application should reconfigure itself as a client by calling the
DbEnv::rep_start()
method, and then call for an
election by calling
DbEnv::rep_elect()
.
The DbEnv::rep_process_message() method will return
DB_REP_HOLDELECTION if an election is needed. The application
should call for an election by calling
DbEnv::rep_elect()
.
The DbEnv::rep_process_message() method will return
DB_REP_IGNORE if this message cannot be processed. This is an
indication that this message is irrelevant to the current replication state (for
example, an old message from a previous master arrives and is processed late).
The DbEnv::rep_process_message() method will return
DB_REP_ISPERM if processing this message results in the
processing of records that are permanent. The maximum LSN of the permanent records
stored is returned.
The DbEnv::rep_process_message() method will return
DB_REP_JOIN_FAILURE if a new master has been chosen but the
client is unable to synchronize with the new master. This is possibly because the client
has turned off automatic internal initialization by setting the
DB_REP_CONF_AUTOINIT
flag to 0. Another possible reason is that
an unencrypted client is attempting to join a replication
group where encryption is use, or an encrypted client is
attempting to join a replication group where encryption is
not in use.
The DbEnv::rep_process_message() method will return
DB_REP_NEWSITE if the system received contact information from a
new environment. The rec parameter contains the
opaque data specified to the
DbEnv::rep_start()
cdata parameter. The application should
take whatever action is needed to establish a communication channel with this new
environment.
The DbEnv::rep_process_message() method will return
DB_REP_NOTPERM if a message carrying a
DB_REP_PERMANENT
flag was processed successfully, but was not written to disk. The LSN of this
record is returned. The application should take whatever action is deemed
necessary to retain its recoverability characteristics.
Unless otherwise specified, the DbEnv::rep_process_message()
method either returns a non-zero error value or throws an
exception that encapsulates a non-zero error value on
failure, and returns 0 on success.
The control parameter should reference a copy of the control parameter specified by Berkeley DB on the sending environment. See the DbEnv::rep_set_transport() method for more information.
The rec parameter should reference a copy of the rec parameter specified by Berkeley DB on the sending environment. See the DbEnv::rep_set_transport() method for more information.
The envid parameter should contain the local identifier that corresponds to the environment that sent the message to be processed (see Replication environment IDs for more information).
If DbEnv::rep_process_message() method returns
DB_REP_NOTPERM then the
ret_lsnp parameter will contain the log sequence
number of this permanent log message that could not be written to disk. If
DbEnv::rep_process_message() method returns
DB_REP_ISPERM then the
ret_lsnp parameter will contain largest log
sequence number of the permanent records that are now written to disk as a
result of processing this message. In all other cases the value of
ret_lsnp is undefined.
The DbEnv::rep_process_message()
method may fail and throw a DbException
exception, encapsulating one of the following non-zero errors, or return one
of the following non-zero errors:
If the database environment was not already configured to communicate with a replication group by a call to DbEnv::rep_set_transport() ; if the database environment was not already opened; if this method is called from a Replication Manager application; or if an invalid flag value or parameter was specified.