mongodb/jstests/sharding/sharding_migrate_cursor1.js

/**
 * SERVER-2068
 *
 * This test is labeled resource intensive because its total io_write is 131MB compared to a median
 * of 5MB across all sharding tests in wiredTiger.
 * @tags: [resource_intensive]
 */
(function() {

var chunkSize = 25;

var s = new ShardingTest(
    {name: "migrate_cursor1", shards: 2, mongos: 1, other: {chunkSize: chunkSize}});

s.adminCommand({enablesharding: "test"});
db = s.getDB("test");
s.ensurePrimaryShard('test', s.shard1.shardName);
t = db.foo;

bigString = "";
stringSize = 1024;

while (bigString.length < stringSize)
    bigString += "asdasdas";

stringSize = bigString.length;
docsPerChunk = Math.ceil((chunkSize * 1024 * 1024) / (stringSize - 12));
numChunks = 5;
numDocs = 20 * docsPerChunk;

print("stringSize: " + stringSize + " docsPerChunk: " + docsPerChunk + " numDocs: " + numDocs);

var bulk = t.initializeUnorderedBulkOp();
for (var i = 0; i < numDocs; i++) {
    bulk.insert({_id: i, s: bigString});
}
assert.writeOK(bulk.execute());

s.adminCommand({shardcollection: "test.foo", key: {_id: 1}});

assert.lt(numChunks, s.config.chunks.find().count(), "initial 1");

primary = s.getPrimaryShard("test").getDB("test").foo;
secondaryName = s.getOther(primary.name);
secondary = secondaryName.getDB("test").foo;

assert.eq(numDocs, primary.count(), "initial 2");
assert.eq(0, secondary.count(), "initial 3");
assert.eq(numDocs, t.count(), "initial 4");

x = primary.find({_id: {$lt: 500}}).batchSize(2);
x.next();  // 1. Create an open cursor

print("start moving chunks...");

// 2. Move chunk from s0 to s1 without waiting for deletion.
// Command returns, but the deletion on s0 will block due to the open cursor.
s.adminCommand({moveChunk: "test.foo", find: {_id: 0}, to: secondaryName.name});

// 3. Start second moveChunk command from s0 to s1.
// This moveChunk should not observe the above deletion as a 'mod', transfer it to s1 and cause
// deletion on s1.
// This moveChunk will wait for deletion.
join = startParallelShell(
    "db.x.insert( {x:1} ); db.adminCommand( { moveChunk : 'test.foo' , find : { _id : " +
    docsPerChunk * 3 + " } , to : '" + secondaryName.name + "', _waitForDelete: true } )");
assert.soon(function() {
    return db.x.count() > 0;
}, "XXX", 30000, 1);

// 4. Close the cursor to enable chunk deletion.
print("itcount: " + x.itcount());

x = null;
for (i = 0; i < 5; i++)
    gc();

print("cursor should be gone");

// 5. Waiting for the second moveChunk to finish its deletion.
// Note the deletion for the first moveChunk may not be finished.
join();

// assert.soon( function(){ return numDocs == t.count(); } , "at end 1" )
// 6. Check the total number of docs on both shards to make sure no doc is lost.
// Use itcount() to ignore orphan docments.
assert.eq(numDocs, t.find().itcount(), "at end 2");

s.stop();
})();