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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#include "mongo/platform/basic.h"
#include "mongo/db/query/cursor_response.h"
#include "mongo/rpc/get_status_from_command_result.h"
#include "mongo/stdx/future.h"
#include "mongo/unittest/integration_test.h"
#include "mongo/unittest/unittest.h"
#include "mongo/util/system_clock_source.h"
namespace mongo {
namespace {
// Obtain a pointer to the global system clock. Used to enforce timeouts in the parallel thread.
auto* const clock = SystemClockSource::get();
std::unique_ptr<DBClientBase> connect(StringData appName) {
std::string errMsg;
auto conn = unittest::getFixtureConnectionString().connect(appName.toString(), errMsg);
uassert(ErrorCodes::SocketException, errMsg, conn);
return conn;
}
void setWaitWithPinnedCursorDuringGetMoreBatchFailpoint(DBClientBase* conn, bool enable) {
auto cmdObj = BSON("configureFailPoint"
<< "waitWithPinnedCursorDuringGetMoreBatch"
<< "mode" << (enable ? "alwaysOn" : "off") << "data"
<< BSON("shouldNotdropLock" << true));
auto reply = conn->runCommand(OpMsgRequest::fromDBAndBody("admin", cmdObj));
ASSERT_OK(getStatusFromCommandResult(reply->getCommandReply()));
}
void setWaitBeforeUnpinningOrDeletingCursorAfterGetMoreBatchFailpoint(DBClientBase* conn,
bool enable) {
auto cmdObj = BSON("configureFailPoint"
<< "waitBeforeUnpinningOrDeletingCursorAfterGetMoreBatch"
<< "mode" << (enable ? "alwaysOn" : "off"));
auto reply = conn->runCommand(OpMsgRequest::fromDBAndBody("admin", cmdObj));
ASSERT_OK(getStatusFromCommandResult(reply->getCommandReply()));
}
bool confirmCurrentOpContents(DBClientBase* conn,
BSONObj curOpMatch,
Milliseconds timeoutMS,
Milliseconds intervalMS = Milliseconds(200)) {
auto curOpCmd = BSON(
"aggregate" << 1 << "cursor" << BSONObj() << "pipeline"
<< BSON_ARRAY(BSON("$currentOp" << BSONObj()) << BSON("$match" << curOpMatch)));
const auto startTime = clock->now();
while (clock->now() - startTime < timeoutMS) {
auto reply = conn->runCommand(OpMsgRequest::fromDBAndBody("admin", curOpCmd));
auto swCursorRes = CursorResponse::parseFromBSON(reply->getCommandReply());
ASSERT_OK(swCursorRes.getStatus());
if (!swCursorRes.getValue().getBatch().empty()) {
return true;
}
sleepFor(intervalMS);
}
return false;
}
} // namespace
TEST(CurrentOpExhaustCursorTest, CanSeeEachExhaustCursorPseudoGetMoreInCurrentOpOutput) {
const NamespaceString testNSS{"exhaust_cursor_currentop.exhaust_cursor_currentop"};
auto conn = connect("curop_exhaust_cursor_test");
// Specifies the amount of time we are willing to wait for a parallel operation to complete.
const auto parallelWaitTimeoutMS = Milliseconds(5 * 60 * 1000);
// We need to set failpoints around getMore which cause it to hang, so only test against a
// single server rather than a replica set or mongoS.
if (conn->isReplicaSetMember() || conn->isMongos()) {
return;
}
// Drop and recreate the test namespace.
conn->dropCollection(testNSS.ns());
for (int i = 0; i < 10; i++) {
auto insertCmd =
BSON("insert" << testNSS.coll() << "documents" << BSON_ARRAY(BSON("a" << i)));
auto reply = conn->runCommand(OpMsgRequest::fromDBAndBody(testNSS.db(), insertCmd));
ASSERT_OK(getStatusFromCommandResult(reply->getCommandReply()));
}
// Enable a failpoint to block getMore during execution.
setWaitWithPinnedCursorDuringGetMoreBatchFailpoint(conn.get(), true);
// Execute a query on a separate thread, with the 'exhaust' flag set.
std::unique_ptr<DBClientBase> queryConnection;
std::unique_ptr<DBClientCursor> queryCursor;
auto queryThread = stdx::async(stdx::launch::async, [&testNSS, &queryConnection, &queryCursor] {
queryConnection = connect("curop_exhaust_cursor_test_bg");
auto projSpec = BSON("_id" << 0 << "a" << 1);
// Issue the initial 'find' with a batchSize of 2 and the exhaust flag set. We then iterate
// through the first batch and confirm that the results are as expected.
queryCursor = queryConnection->query(testNSS, {}, 0, 0, &projSpec, QueryOption_Exhaust, 2);
for (int i = 0; i < 2; ++i) {
ASSERT_BSONOBJ_EQ(queryCursor->nextSafe(), BSON("a" << i));
}
// Having exhausted the two results returned by the initial find, we set the batchSize to 1
// and issue a single getMore via DBClientCursor::more(). Because the 'exhaust' flag is set,
// the server will generate a series of internal getMores and stream them back to the client
// until the cursor is exhausted, without the client sending any further getMore requests.
// We expect this request to hang at the 'waitWithPinnedCursorDuringGetMoreBatch' failpoint.
queryCursor->setBatchSize(1);
ASSERT(queryCursor->more());
});
// Ensure that, regardless of whether the test completes or fails, we release all failpoints.
ON_BLOCK_EXIT([&conn, &queryThread] {
setWaitWithPinnedCursorDuringGetMoreBatchFailpoint(conn.get(), false);
setWaitBeforeUnpinningOrDeletingCursorAfterGetMoreBatchFailpoint(conn.get(), false);
queryThread.wait();
});
// Wait until the parallel operation initializes its cursor.
const auto startTime = clock->now();
while (!queryCursor && (clock->now() - startTime < parallelWaitTimeoutMS)) {
sleepFor(Milliseconds(10));
}
ASSERT(queryCursor);
// We expect that the server, having received the first {batchSize: 1} getMore for the parallel
// thread's exhaust cursor, will produce a series of pseudo-getMores internally and stream the
// results back to the client until the cursor is exhausted. Here, we verify that each of these
// pseudo-getMores appear in the $currentOp output.
for (int i = 2; i < 10; ++i) {
// Generate a currentOp filter based on the cursorId and the cumulative nDocsReturned.
const auto curOpMatch = BSON("command.collection"
<< "exhaust_cursor_currentop"
<< "command.getMore" << queryCursor->getCursorId() << "msg"
<< "waitWithPinnedCursorDuringGetMoreBatch"
<< "cursor.nDocsReturned" << i);
// Confirm that the exhaust getMore appears in the $currentOp output.
ASSERT(confirmCurrentOpContents(conn.get(), curOpMatch, parallelWaitTimeoutMS));
// Airlock the failpoint by releasing it only after we enable a post-getMore failpoint. This
// ensures that no subsequent getMores can run before we re-enable the original failpoint.
setWaitBeforeUnpinningOrDeletingCursorAfterGetMoreBatchFailpoint(conn.get(), true);
setWaitWithPinnedCursorDuringGetMoreBatchFailpoint(conn.get(), false);
// Confirm that the getMore completed its batch and hit the post-getMore failpoint.
ASSERT(confirmCurrentOpContents(
conn.get(),
BSON("command.getMore" << queryCursor->getCursorId() << "msg"
<< "waitBeforeUnpinningOrDeletingCursorAfterGetMoreBatch"),
parallelWaitTimeoutMS));
// Re-enable the original failpoint to catch the next getMore, and release the current one.
setWaitWithPinnedCursorDuringGetMoreBatchFailpoint(conn.get(), true);
setWaitBeforeUnpinningOrDeletingCursorAfterGetMoreBatchFailpoint(conn.get(), false);
}
}
} // namespace mongo
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