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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.
*/
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kWrite
#include "mongo/db/concurrency/deferred_writer.h"
#include "mongo/db/catalog/create_collection.h"
#include "mongo/db/client.h"
#include "mongo/db/concurrency/write_conflict_exception.h"
#include "mongo/db/db_raii.h"
#include "mongo/db/operation_context.h"
#include "mongo/logv2/log.h"
#include "mongo/util/concurrency/idle_thread_block.h"
#include "mongo/util/concurrency/thread_pool.h"
namespace mongo {
namespace {
auto kLogInterval = stdx::chrono::minutes(1);
}
void DeferredWriter::_logFailure(const Status& status) {
if (TimePoint::clock::now() - _lastLogged > kLogInterval) {
LOGV2(20516,
"Unable to write to collection {namespace}: {error}",
"Unable to write to collection",
"namespace"_attr = _nss.toString(),
"error"_attr = status);
_lastLogged = stdx::chrono::system_clock::now();
}
}
void DeferredWriter::_logDroppedEntry() {
_droppedEntries += 1;
if (TimePoint::clock::now() - _lastLoggedDrop > kLogInterval) {
LOGV2(
20517,
"Deferred write buffer for {nss} is full. {droppedEntries} entries have been dropped.",
"nss"_attr = _nss.toString(),
"droppedEntries"_attr = _droppedEntries);
_lastLoggedDrop = stdx::chrono::system_clock::now();
_droppedEntries = 0;
}
}
Status DeferredWriter::_makeCollection(OperationContext* opCtx) {
BSONObjBuilder builder;
builder.append("create", _nss.coll());
builder.appendElements(_collectionOptions.toBSON());
try {
return createCollection(opCtx, _nss.db().toString(), builder.obj().getOwned());
} catch (const DBException& exception) {
return exception.toStatus();
}
}
StatusWith<std::unique_ptr<AutoGetCollection>> DeferredWriter::_getCollection(
OperationContext* opCtx) {
std::unique_ptr<AutoGetCollection> agc;
agc = std::make_unique<AutoGetCollection>(opCtx, _nss, MODE_IX);
while (!agc->getCollection()) {
// Release the previous AGC's lock before trying to rebuild the collection.
agc.reset();
Status status = _makeCollection(opCtx);
if (!status.isOK()) {
return status;
}
agc = std::make_unique<AutoGetCollection>(opCtx, _nss, MODE_IX);
}
return std::move(agc);
}
void DeferredWriter::_worker(InsertStatement stmt) {
auto uniqueOpCtx = Client::getCurrent()->makeOperationContext();
OperationContext* opCtx = uniqueOpCtx.get();
auto result = _getCollection(opCtx);
if (!result.isOK()) {
_logFailure(result.getStatus());
return;
}
auto agc = std::move(result.getValue());
const CollectionPtr& collection = agc->getCollection();
Status status = writeConflictRetry(opCtx, "deferred insert", _nss.ns(), [&] {
WriteUnitOfWork wuow(opCtx);
Status status = collection->insertDocument(opCtx, stmt, nullptr, false);
if (!status.isOK()) {
return status;
}
wuow.commit();
return Status::OK();
});
stdx::lock_guard<Latch> lock(_mutex);
_numBytes -= stmt.doc.objsize();
// If a write to a deferred collection fails, periodically tell the log.
if (!status.isOK()) {
_logFailure(status);
}
}
DeferredWriter::DeferredWriter(NamespaceString nss, CollectionOptions opts, int64_t maxSize)
: _collectionOptions(opts),
_maxNumBytes(maxSize),
_nss(nss),
_numBytes(0),
_droppedEntries(0),
_lastLogged(TimePoint::clock::now() - kLogInterval) {}
DeferredWriter::~DeferredWriter() {}
void DeferredWriter::startup(std::string workerName) {
// We should only start up once.
invariant(!_pool);
ThreadPool::Options options;
options.poolName = "deferred writer pool";
options.threadNamePrefix = workerName;
options.minThreads = 0;
options.maxThreads = 1;
options.onCreateThread = [](const std::string& name) { Client::initThread(name); };
_pool = std::make_unique<ThreadPool>(options);
_pool->startup();
}
void DeferredWriter::shutdown(void) {
// If we never allocated the pool, no cleanup is necessary.
if (!_pool) {
return;
}
_pool->waitForIdle();
_pool->shutdown();
_pool->join();
}
bool DeferredWriter::insertDocument(BSONObj obj) {
// We can't insert documents if we haven't been started up.
invariant(_pool);
stdx::lock_guard<Latch> lock(_mutex);
// Check if we're allowed to insert this object.
if (_numBytes + obj.objsize() >= _maxNumBytes) {
// If not, drop it. We always drop new entries rather than old ones; that way the caller
// knows at the time of the call that the entry was dropped.
_logDroppedEntry();
return false;
}
// Add the object to the buffer.
_numBytes += obj.objsize();
_pool->schedule([this, obj](auto status) {
fassert(40588, status);
_worker(InsertStatement(obj.getOwned()));
});
return true;
}
int64_t DeferredWriter::getDroppedEntries() {
return _droppedEntries;
}
} // namespace mongo
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