/**
 * This test inserts documents with large, duplicated keys. This will result in significant
 * fragmentation in the buffer allocator for index builds because we generate keys that end up being
 * deduplicated, but can still pin memory. We want to ensure that we track this fragmented memory
 * and spill often to avoid exceeding any memory limits.
 *
 * @tags: [
 *   requires_replication,
 * ]
 */
(function() {
const maxMemUsageMB = 50;
const replSet = new ReplSetTest({
    nodes: 1,
    nodeOptions: {setParameter: {maxIndexBuildMemoryUsageMegabytes: maxMemUsageMB}},
});
replSet.startSet();
replSet.initiate();

const primary = replSet.getPrimary();
const testDB = primary.getDB('test');
const coll = testDB.index_build_large_array;

// Create documents with many large, duplicated keys.
const docs = 10 * 1000;
const bigArr = new Array(100).fill('x');
const bulk = coll.initializeUnorderedBulkOp();
for (let i = 0; i < docs; i++) {
    bulk.insert({a: i + 'x'.repeat(10 * 1000), arr: bigArr});
}
bulk.execute();

coll.createIndex({arr: 1, a: 1});

const serverStatus = testDB.serverStatus();
assert(serverStatus.hasOwnProperty('indexBulkBuilder'),
       'indexBuildBuilder section missing: ' + tojson(serverStatus));

const section = serverStatus.indexBulkBuilder;
print("Index build stats", tojson(section));

const numSpills = section.bytesSpilledUncompressed;
assert.gt(numSpills, 0, tojson(section));

// Ensure the uncompressed memory usage per spill does not exceed the limit.
assert.between(
    0, section.bytesSpilledUncompressed / numSpills, maxMemUsageMB * 1024 * 1024, tojson(section));

replSet.stopSet();
})();