mongodb/jstests/capped7.js

// Test NamespaceDetails::emptyCappedCollection via 'emptycapped' command

Random.setRandomSeed();

db.capped7.drop();
db._dbCommand( { create: "capped7", capped: true, size: 1000, $nExtents: 11, autoIndexId: false } );
tzz = db.capped7;

var ten = new Array( 11 ).toString().replace( /,/g, "-" );

count = 0;

/**
 * Insert new documents until the capped collection loops and the document
 * count doesn't increase on insert.
 */
function insertUntilFull() {
count = tzz.count();
    var j = 0;
while( 1 ) {
    tzz.save( {i:ten,j:j++} );
    var newCount = tzz.count();
    if ( count == newCount ) {
        break;
    }
    count = newCount;
}
}

insertUntilFull();

// oldCount == count before empty
oldCount = count;

assert.eq.automsg( "11", "tzz.stats().numExtents" );

// oldSize == size before empty
var oldSize = tzz.stats().storageSize;

assert.commandWorked( db._dbCommand( { emptycapped: "capped7" } ) );

// check that collection storage parameters are the same after empty
assert.eq.automsg( "11", "tzz.stats().numExtents" );
assert.eq.automsg( "oldSize", "tzz.stats().storageSize" );

// check that the collection is empty after empty
assert.eq.automsg( "0", "tzz.find().itcount()" );
assert.eq.automsg( "0", "tzz.count()" );

// check that we can reuse the empty collection, inserting as many documents
// as we were able to the first time through.
insertUntilFull();
assert.eq.automsg( "oldCount", "count" );
assert.eq.automsg( "oldCount", "tzz.find().itcount()" );
assert.eq.automsg( "oldCount", "tzz.count()" );

assert.eq.automsg( "11", "tzz.stats().numExtents" );
var oldSize = tzz.stats().storageSize;

assert.commandWorked( db._dbCommand( { emptycapped: "capped7" } ) );

// check that the collection storage parameters are unchanged after another empty
assert.eq.automsg( "11", "tzz.stats().numExtents" );
assert.eq.automsg( "oldSize", "tzz.stats().storageSize" );

// insert an arbitrary number of documents
var total = Random.randInt( 2000 );
for( var j = 1; j <= total; ++j ) {
    tzz.save( {i:ten,j:j} );
    // occasionally check that only the oldest documents are removed to make room
    // for the newest documents
    if ( Random.rand() > 0.95 ) {
        assert.automsg( "j >= tzz.count()" );
        assert.eq.automsg( "tzz.count()", "tzz.find().itcount()" );
        var c = tzz.find().sort( {$natural:-1} );
        var k = j;
        assert.automsg( "c.hasNext()" );
        while( c.hasNext() ) {
            assert.eq.automsg( "c.next().j", "k--" );
        }
        // check the same thing with a reverse iterator as well
        var c = tzz.find().sort( {$natural:1} );
        assert.automsg( "c.hasNext()" );
        while( c.hasNext() ) {
            assert.eq.automsg( "c.next().j", "++k" );
        }        
        assert.eq.automsg( "j", "k" );
    }
}