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// @tags: [
// # Cannot implicitly shard accessed collections because of following errmsg: A single
// # update/delete on a sharded collection must contain an exact match on _id or contain the
// # shard key.
// assumes_unsharded_collection,
//
// # Uses $where operator
// requires_scripting,
// ]
// Ensures that find and modify will not apply an update to a document which, due to a concurrent
// modification, no longer matches the query predicate.
(function() {
"use strict";
// Repeat the test a few times, as the timing of the yield means it won't fail consistently.
for (var i = 0; i < 3; i++) {
var t = db.find_and_modify_concurrent;
t.drop();
assert.commandWorked(t.ensureIndex({a: 1}));
assert.commandWorked(t.ensureIndex({b: 1}));
assert.writeOK(t.insert({_id: 1, a: 1, b: 1}));
var join = startParallelShell(
"db.find_and_modify_concurrent.update({a: 1, b: 1}, {$inc: {a: 1}});");
// Due to the sleep, we expect this find and modify to yield before updating the
// document.
var res = t.findAndModify(
{query: {a: 1, b: 1, $where: "sleep(100); return true;"}, update: {$inc: {a: 1}}});
join();
var docs = t.find().toArray();
assert.eq(docs.length, 1);
// Both the find and modify and the update operations look for a document with a==1,
// and then increment 'a' by 1. One should win the race and set a=2. The other should
// fail to find a match. The assertion is that 'a' got incremented once (not zero times
// and not twice).
assert.eq(docs[0].a, 2);
}
})();
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