[pybsddb] Replication stat question

[Sury Soni]

Here is the solution.

 

Seems like, python implementation around C/C++ function rep_stat() is
altogether missing.

 

Hence, I simply copied code from repmgr_stat() wrapper and modified the
statistic receiving object type and fetched statistics of my interest in
the dictionary.

 

I would have loved to implement full thing and provided the patch, but I
am bit lazy to learn how to get patch and submit more professionally.

 

But following is a quick code reference for those who are stuck (or will
stuck) in similar situation.

 

In file, Modules/_bsddb.c, 

 

1. find implementation code for 

 

static PyObject*

DBEnv_repmgr_stat(DBEnvObject* self, PyObject* args, PyObject *kwargs)

 

2. Copy paste full function implementation just next to it.

 

3. Change 

 

DB_REPMGR_STAT *statp 

to 

DB_REP_STAT *statp 

 

4. Pick fields of DB_REP_STAT of your interest or someone implement it
fully. 

Ref.
http://www.oracle.com/technology/documentation/berkeley-db/db/api_c/rep_
stat.html

 

 

5. Sample code as follows:

 

static PyObject*

DBEnv_rep_stat(DBEnvObject* self, PyObject* args, PyObject *kwargs)

{

    int err;

    int flags=0;

    DB_REP_STAT *statp;

    PyObject *stats;

    static char* kwnames[] = { "flags", NULL };

 

    if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|i:rep_stat",

                kwnames, &flags))

    {

        return NULL;

    }

    CHECK_ENV_NOT_CLOSED(self);

    MYDB_BEGIN_ALLOW_THREADS;

    err = self->db_env->rep_stat(self->db_env, &statp, flags);

    MYDB_END_ALLOW_THREADS;

    RETURN_IF_ERR();

 

    stats=PyDict_New();

    if (stats == NULL) {

        free(statp);

        return NULL;

    }

 

#define MAKE_ENTRY(name)  _addIntToDict(stats, #name, statp->st_##name)

#define MAKE_DB_LSN_ENTRY(name) _addDB_lsnToDict(stats, #name,
statp->st_##name)

    MAKE_DB_LSN_ENTRY(next_lsn);

#undef MAKE_DB_LSN_ENTRY

#undef MAKE_ENTRY

 

    free(statp);

    return stats;

}

 

6. Add entry into following array

static PyMethodDef DBEnv_methods[] = {

...

...

#if (DBVER >= 46)

    {"repmgr_stat", (PyCFunction)DBEnv_repmgr_stat,

        METH_VARARGS|METH_KEYWORDS},

    {"rep_stat", (PyCFunction)DBEnv_rep_stat,

        METH_VARARGS|METH_KEYWORDS},

    {"repmgr_stat_print", (PyCFunction)DBEnv_repmgr_stat_print,

        METH_VARARGS|METH_KEYWORDS},

#endif

...

...

 

 

7. That's it, build, test and install.

 

8. And yes, I have tried to small test case in existing test case, which
is not appropriate:

 

# Code to add few records into master.

# Write yourself, I picked the place where in some test, it was adding
some items.

 

        statm = self.dbenvMaster.rep_stat()

        m_lsn = statm['next_lsn']

        statc = self.dbenvClient.rep_stat()

        c_lsn = statc['next_lsn']

        self.assertEquals(m_lsn, c_lsn)

 

 

I hope it is useful. Even though, my presentation is not alright, but
thanks to this community who made my life lot easier by implementing
this wrapper API.

 

Regards,

 

Surya

 

________________________________

From: pybsddb-bounces at argo.es [mailto:pybsddb-bounces at argo.es] On Behalf
Of Sury Soni
Sent: Wednesday, 1 October 2008 11:50 AM
To: pybsddb at argo.es
Subject: [pybsddb] Replication stat question

 

Hi There,

 

I am using pybsddb3 (3.4.7.2) wrapped around db4.6.21 on freebsd 7.

 

I am curious to get st_next_lsn DB_LSN attribute from replication stats.

 

How can I get?

 

My curiosity is to get last LSN number on replication client which can
be later matched with master to verify how close up-to-date client is
with the master.

 

Repmgr_stat does not fill this attribute and rep_stat is virtual
function but have this attribute. How can I get this attribute for
default replication manager.

 

Regards,

____________________________________
Sury Prakash Soni
Developer
____________________________________

Next Digital
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VIC 3000 Australia
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