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// Verifies mongos uses a versioned routing table to target subsequent requests in transactions with
// snapshot level read concern.
//
// @tags: [
// requires_find_command,
// requires_sharding,
// uses_multi_shard_transaction,
// uses_transactions,
// ]
(function() {
"use strict";
load("jstests/sharding/libs/sharded_transactions_helpers.js");
function expectChunks(st, ns, chunks) {
for (let i = 0; i < chunks.length; i++) {
assert.eq(chunks[i],
st.s.getDB("config").chunks.count({ns: ns, shard: st["shard" + i].shardName}),
"unexpected number of chunks on shard " + i);
}
}
const dbName = "test";
const collName = "foo";
const ns = dbName + '.' + collName;
const st = new ShardingTest({shards: 3, mongos: 1, config: 1});
// Set up one sharded collection with 2 chunks, both on the primary shard.
assert.writeOK(st.s.getDB(dbName)[collName].insert({_id: -5}, {writeConcern: {w: "majority"}}));
assert.writeOK(st.s.getDB(dbName)[collName].insert({_id: 5}, {writeConcern: {w: "majority"}}));
assert.commandWorked(st.s.adminCommand({enableSharding: dbName}));
st.ensurePrimaryShard(dbName, st.shard0.shardName);
assert.commandWorked(st.s.adminCommand({shardCollection: ns, key: {_id: 1}}));
assert.commandWorked(st.s.adminCommand({split: ns, middle: {_id: 0}}));
expectChunks(st, ns, [2, 0, 0]);
// Temporarily move a chunk to Shard2, to avoid picking a global read timestamp before the
// sharding metadata cache collections are created.
assert.commandWorked(st.s.adminCommand({moveChunk: ns, find: {_id: 5}, to: st.shard2.shardName}));
assert.commandWorked(st.s.adminCommand({moveChunk: ns, find: {_id: 5}, to: st.shard1.shardName}));
expectChunks(st, ns, [1, 1, 0]);
// First command targets the first chunk, the second command targets the second chunk.
const kCommandTestCases = [
{
name: "aggregate",
commandFuncs: [
(coll) => coll.aggregate({$match: {_id: -5}}).itcount(),
(coll) => coll.aggregate({$match: {_id: 5}}).itcount(),
]
},
{
name: "find",
commandFuncs: [
(coll) => coll.find({_id: -5}).itcount(),
(coll) => coll.find({_id: 5}).itcount(),
]
}
];
function runTest(testCase) {
const cmdName = testCase.name;
const targetChunk1Func = testCase.commandFuncs[0];
const targetChunk2Func = testCase.commandFuncs[1];
jsTestLog("Testing " + cmdName);
expectChunks(st, ns, [1, 1, 0]);
const session = st.s.startSession();
const sessionDB = session.getDatabase(dbName);
const sessionColl = sessionDB[collName];
session.startTransaction({readConcern: {level: "snapshot"}});
// Start a transaction on Shard0 which will select and pin a global read timestamp.
assert.eq(targetChunk1Func(sessionColl),
1,
"expected to find document in first chunk, cmd: " + cmdName);
// Move a chunk from Shard1 to Shard2 outside of the transaction. This will happen at a
// later logical time than the transaction's read timestamp.
assert.commandWorked(
st.s.adminCommand({moveChunk: ns, find: {_id: 5}, to: st.shard2.shardName}));
// Target a document in the chunk that was moved. The router should get a stale shard
// version from Shard1 then retry on Shard1 and see the document.
assert.eq(targetChunk2Func(sessionColl),
1,
"expected to find document in second chunk, cmd: " + cmdName);
assert.commandWorked(session.commitTransaction_forTesting());
// Move the chunk back to Shard1 for the next iteration.
assert.commandWorked(
st.s.adminCommand({moveChunk: ns, find: {_id: 5}, to: st.shard1.shardName}));
}
kCommandTestCases.forEach(runTest);
st.stop();
})();
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