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/**
* Copyright (C) 2023-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/db/exec/spool.h"
// IWYU pragma: no_include "ext/alloc_traits.h"
#include <cstddef>
#include <string>
#include <utility>
#include "mongo/base/error_codes.h"
#include "mongo/db/query/query_knobs_gen.h"
#include "mongo/platform/atomic_word.h"
#include "mongo/util/assert_util.h"
namespace {
/**
* Generates a new file name on each call using a static, atomic and monotonically increasing
* number.
*
* Each user of the Sorter must implement this function to ensure that all temporary files that the
* Sorter instances produce are uniquely identified using a unique file name extension with separate
* atomic variable. This is necessary because the sorter.cpp code is separately included in multiple
* places, rather than compiled in one place and linked, and so cannot provide a globally unique ID.
*/
std::string nextFileName() {
static mongo::AtomicWord<unsigned> spoolFileCounter;
return "ext-spool." + std::to_string(spoolFileCounter.fetchAndAdd(1));
}
// Helper to allocate a new working set member to hold the RecordId, set the output parameter, and
// return ADVANCED.
mongo::PlanStage::StageState allocateResultAndAdvance(mongo::WorkingSet* ws,
mongo::WorkingSetID* out,
mongo::RecordId&& recordId) {
*out = ws->allocate();
auto member = ws->get(*out);
member->recordId = std::move(recordId);
// Only store the record id, not any index information or full objects. This is to
// reduce memory and disk usage - it is the responsibility of our caller to fetch the records.
ws->transitionToRecordIdAndIdx(*out);
return mongo::PlanStage::ADVANCED;
}
} // namespace
namespace mongo {
const char* SpoolStage::kStageType = "SPOOL";
SpoolStage::SpoolStage(ExpressionContext* expCtx, WorkingSet* ws, std::unique_ptr<PlanStage> child)
: PlanStage(expCtx, std::move(child), kStageType),
_ws(ws),
_memTracker(expCtx->allowDiskUse, internalQueryMaxSpoolMemoryUsageBytes.load()) {
_specificStats.maxMemoryUsageBytes = _memTracker.maxAllowedMemoryUsageBytes();
_specificStats.maxDiskUsageBytes = internalQueryMaxSpoolDiskUsageBytes.load();
}
bool SpoolStage::isEOF() {
return _spillFileIters.empty() && _nextIndex == static_cast<int>(_buffer.size());
}
std::unique_ptr<PlanStageStats> SpoolStage::getStats() {
_commonStats.isEOF = isEOF();
auto ret = std::make_unique<PlanStageStats>(_commonStats, stageType());
ret->specific = std::make_unique<SpoolStats>(_specificStats);
ret->children.emplace_back(child()->getStats());
return ret;
}
void SpoolStage::spill() {
uassert(ErrorCodes::QueryExceededMemoryLimitNoDiskUseAllowed,
"Exceeded memory limit for spool, but didn't allow external sort. Set "
"allowDiskUseByDefault:true to opt in.",
_memTracker.allowDiskUse());
uassert(7443700,
"Exceeded disk use limit for spool",
_specificStats.spilledDataStorageSize < _specificStats.maxDiskUsageBytes);
// Initialize '_file' in a lazy manner only when it is needed.
if (!_file) {
_spillStats = std::make_unique<SorterFileStats>(nullptr /* sorterTracker */);
_file = std::make_shared<Sorter<RecordId, NullValue>::File>(
expCtx()->tempDir + "/" + nextFileName(), _spillStats.get());
}
auto opts = SortOptions().TempDir(expCtx()->tempDir);
opts.FileStats(_spillStats.get());
SortedFileWriter<RecordId, NullValue> writer(opts, _file);
_specificStats.spilledRecords += _buffer.size();
for (size_t i = 0; i < _buffer.size(); ++i) {
writer.addAlreadySorted(_buffer[i], NullValue());
}
_spillFileIters.emplace_back(writer.done());
_buffer.clear();
_memTracker.resetCurrent();
++_specificStats.spills;
_specificStats.spilledDataStorageSize = _spillStats->bytesSpilled();
_specificStats.spilledUncompressedDataSize = _spillStats->bytesSpilledUncompressed();
}
PlanStage::StageState SpoolStage::doWork(WorkingSetID* out) {
if (isEOF()) {
return PlanStage::IS_EOF;
}
if (_nextIndex < 0) {
// We have not yet received EOF from our child yet. Eagerly consume and cache results as
// long as the child keeps advancing (we'll propagate yields and NEED_TIME).
WorkingSetID id = WorkingSet::INVALID_ID;
StageState status = child()->work(&id);
while (status == PlanStage::ADVANCED) {
// The child has returned another result, put it in our cache.
auto member = _ws->get(id);
tassert(
7443500, "WSM passed to spool stage must have a RecordId", member->hasRecordId());
auto memUsage = member->recordId.memUsage();
_specificStats.totalDataSizeBytes += memUsage;
_memTracker.add(memUsage);
_buffer.emplace_back(std::move(member->recordId));
if (!_memTracker.withinMemoryLimit()) {
spill();
}
// We've cached the RecordId, so go ahead and free the object in the working set.
_ws->free(id);
// Ask the child for another record.
status = child()->work(&id);
}
if (status != PlanStage::IS_EOF) {
*out = id;
return status;
}
// The child has returned all of its results. Fall through and begin consuming the results
// from our buffer.
}
// First, return results from any spills we may have.
while (!_spillFileIters.empty()) {
if (_spillFileIters.front()->more()) {
auto [recordId, _] = _spillFileIters.front()->next();
return allocateResultAndAdvance(_ws, out, std::move(recordId));
}
_spillFileIters.pop_front();
}
// Increment to the next element in our buffer. Note that we increment the index *first* so that
// we will return EOF in a call to doWork() before isEOF() returns true.
if (++_nextIndex == static_cast<int>(_buffer.size())) {
return PlanStage::IS_EOF;
}
return allocateResultAndAdvance(_ws, out, std::move(_buffer[_nextIndex]));
}
} // namespace mongo
#include "mongo/db/sorter/sorter.cpp"
// Explicit instantiation unneeded since we aren't exposing Sorter outside of this file.
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