// Tests whether a split and a migrate in a sharded cluster preserve the epoch

var st = new ShardingTest( { shards : 2, mongos : 1, separateConfig : 1  } )
// Stop balancer, it'll interfere
st.stopBalancer()

var config = st.s.getDB( "config" )
var admin = st.s.getDB( "admin" )
var coll = st.s.getCollection( "foo.bar" )

// First enable sharding
admin.runCommand({ enableSharding : coll.getDB() + "" })
admin.runCommand({ shardCollection : coll  + "", key : { _id : 1 } })

var primary = config.databases.find({ _id : coll.getDB() + "" }).primary
var notPrimary = null
config.shards.find().forEach( function( doc ){ if( doc._id != primary ) notPrimary = doc._id } )

var createdEpoch = null;
var checkEpochs = function(){
    config.chunks.find({ ns : coll + "" }).forEach( function( chunk ){
        
        // Make sure the epochs exist, are non-zero, and are consistent
        assert( chunk.lastmodEpoch );
        print( chunk.lastmodEpoch + "" );
        assert.neq( chunk.lastmodEpoch + "", "000000000000000000000000" )
        if( createdEpoch == null ) createdEpoch = chunk.lastmodEpoch
        else assert.eq( createdEpoch, chunk.lastmodEpoch )
        
    })
}   

checkEpochs();

// Now do a split
printjson( admin.runCommand({ split : coll + "", middle : { _id : 0 } }) )

// Check all the chunks for epochs
checkEpochs();

// Now do a migrate
printjson( admin.runCommand({ moveChunk : coll + "", find : { _id : 0 }, to : notPrimary }) )

// Check all the chunks for epochs
checkEpochs();

st.stop()