/**
* Copyright (C) 2017 MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see .
*
* 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 GNU Affero General 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_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kWrite
#include "mongo/platform/basic.h"
#include "mongo/db/session_catalog.h"
#include
#include "mongo/db/db_raii.h"
#include "mongo/db/dbdirectclient.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/service_context.h"
#include "mongo/rpc/get_status_from_command_result.h"
#include "mongo/stdx/memory.h"
#include "mongo/util/log.h"
namespace mongo {
namespace {
struct CheckedOutSession {
CheckedOutSession(ScopedCheckedOutSession&& session) : scopedSession(std::move(session)) {}
ScopedCheckedOutSession scopedSession;
// This number gets incremented every time a request tries to check out this session, including
// the cases when it was already checked out. Level of 0 means that it's available or is
// completely released.
int checkOutNestingLevel = 0;
};
const auto sessionTransactionTableDecoration =
ServiceContext::declareDecoration>();
const auto operationSessionDecoration =
OperationContext::declareDecoration>();
} // namespace
SessionCatalog::SessionCatalog(ServiceContext* serviceContext) : _serviceContext(serviceContext) {}
SessionCatalog::~SessionCatalog() {
stdx::lock_guard lg(_mutex);
for (const auto& entry : _txnTable) {
auto& sri = entry.second;
invariant(!sri->checkedOut);
}
}
void SessionCatalog::create(ServiceContext* service) {
auto& sessionTransactionTable = sessionTransactionTableDecoration(service);
invariant(!sessionTransactionTable);
sessionTransactionTable.emplace(service);
}
void SessionCatalog::reset_forTest(ServiceContext* service) {
auto& sessionTransactionTable = sessionTransactionTableDecoration(service);
sessionTransactionTable.reset();
}
SessionCatalog* SessionCatalog::get(OperationContext* opCtx) {
return get(opCtx->getServiceContext());
}
SessionCatalog* SessionCatalog::get(ServiceContext* service) {
auto& sessionTransactionTable = sessionTransactionTableDecoration(service);
invariant(sessionTransactionTable);
return sessionTransactionTable.get_ptr();
}
boost::optional SessionCatalog::getTransactionTableUUID(OperationContext* opCtx) {
AutoGetCollection autoColl(opCtx, NamespaceString::kSessionTransactionsTableNamespace, MODE_IS);
const auto coll = autoColl.getCollection();
if (coll == nullptr) {
return boost::none;
}
return coll->uuid();
}
void SessionCatalog::onStepUp(OperationContext* opCtx) {
invalidateSessions(opCtx, boost::none);
DBDirectClient client(opCtx);
const size_t initialExtentSize = 0;
const bool capped = false;
const bool maxSize = 0;
BSONObj result;
if (client.createCollection(NamespaceString::kSessionTransactionsTableNamespace.ns(),
initialExtentSize,
capped,
maxSize,
&result)) {
return;
}
const auto status = getStatusFromCommandResult(result);
if (status == ErrorCodes::NamespaceExists) {
return;
}
uasserted(status.code(),
str::stream() << "Failed to create the "
<< NamespaceString::kSessionTransactionsTableNamespace.ns()
<< " collection due to "
<< status.reason());
}
ScopedCheckedOutSession SessionCatalog::checkOutSession(OperationContext* opCtx) {
invariant(!opCtx->lockState()->isLocked());
invariant(opCtx->getLogicalSessionId());
const auto lsid = *opCtx->getLogicalSessionId();
stdx::unique_lock ul(_mutex);
auto sri = _getOrCreateSessionRuntimeInfo(opCtx, lsid, ul);
// Wait until the session is no longer checked out
opCtx->waitForConditionOrInterrupt(
sri->availableCondVar, ul, [&sri]() { return !sri->checkedOut; });
invariant(!sri->checkedOut);
sri->checkedOut = true;
return ScopedCheckedOutSession(opCtx, ScopedSession(std::move(sri)));
}
ScopedSession SessionCatalog::getOrCreateSession(OperationContext* opCtx,
const LogicalSessionId& lsid) {
invariant(!opCtx->lockState()->isLocked());
invariant(!opCtx->getLogicalSessionId());
invariant(!opCtx->getTxnNumber());
auto ss = [&] {
stdx::unique_lock ul(_mutex);
return ScopedSession(_getOrCreateSessionRuntimeInfo(opCtx, lsid, ul));
}();
// Perform the refresh outside of the mutex
ss->refreshFromStorageIfNeeded(opCtx);
return ss;
}
void SessionCatalog::invalidateSessions(OperationContext* opCtx,
boost::optional singleSessionDoc) {
uassert(40528,
str::stream() << "Direct writes against "
<< NamespaceString::kSessionTransactionsTableNamespace.ns()
<< " cannot be performed using a transaction or on a session.",
!opCtx->getLogicalSessionId());
const auto invalidateSessionFn = [&](WithLock, SessionRuntimeInfoMap::iterator it) {
auto& sri = it->second;
sri->txnState.invalidate();
// We cannot remove checked-out sessions from the cache, because operations expect to find
// them there to check back in
if (!sri->checkedOut) {
_txnTable.erase(it);
}
};
stdx::lock_guard lg(_mutex);
if (singleSessionDoc) {
const auto lsid = LogicalSessionId::parse(IDLParserErrorContext("lsid"),
singleSessionDoc->getField("_id").Obj());
auto it = _txnTable.find(lsid);
if (it != _txnTable.end()) {
invalidateSessionFn(lg, it);
}
} else {
auto it = _txnTable.begin();
while (it != _txnTable.end()) {
invalidateSessionFn(lg, it++);
}
}
}
std::shared_ptr SessionCatalog::_getOrCreateSessionRuntimeInfo(
OperationContext* opCtx, const LogicalSessionId& lsid, stdx::unique_lock& ul) {
invariant(!opCtx->lockState()->inAWriteUnitOfWork());
auto it = _txnTable.find(lsid);
if (it == _txnTable.end()) {
it = _txnTable.emplace(lsid, std::make_shared(lsid)).first;
}
return it->second;
}
void SessionCatalog::_releaseSession(const LogicalSessionId& lsid) {
stdx::lock_guard lg(_mutex);
auto it = _txnTable.find(lsid);
invariant(it != _txnTable.end());
auto& sri = it->second;
invariant(sri->checkedOut);
sri->checkedOut = false;
sri->availableCondVar.notify_one();
}
OperationContextSession::OperationContextSession(OperationContext* opCtx, bool checkOutSession)
: _opCtx(opCtx) {
if (!opCtx->getLogicalSessionId()) {
return;
}
if (!checkOutSession) {
// The session may have already been checked out by this operation, so bump the nesting
// level if necessary to avoid resetting the session when this command completes.
if (auto& checkedOutSession = operationSessionDecoration(opCtx)) {
checkedOutSession->checkOutNestingLevel++;
}
return;
}
auto& checkedOutSession = operationSessionDecoration(opCtx);
if (!checkedOutSession) {
auto sessionTransactionTable = SessionCatalog::get(opCtx);
checkedOutSession.emplace(sessionTransactionTable->checkOutSession(opCtx));
}
const auto session = checkedOutSession->scopedSession.get();
invariant(opCtx->getLogicalSessionId() == session->getSessionId());
checkedOutSession->checkOutNestingLevel++;
if (checkedOutSession->checkOutNestingLevel > 1) {
return;
}
checkedOutSession->scopedSession->refreshFromStorageIfNeeded(opCtx);
if (opCtx->getTxnNumber()) {
checkedOutSession->scopedSession->beginTxn(opCtx, *opCtx->getTxnNumber());
}
}
OperationContextSession::~OperationContextSession() {
auto& checkedOutSession = operationSessionDecoration(_opCtx);
if (checkedOutSession) {
invariant(checkedOutSession->checkOutNestingLevel > 0);
if (--checkedOutSession->checkOutNestingLevel == 0) {
checkedOutSession.reset();
}
}
}
Session* OperationContextSession::get(OperationContext* opCtx) {
auto& checkedOutSession = operationSessionDecoration(opCtx);
if (checkedOutSession) {
return checkedOutSession->scopedSession.get();
}
return nullptr;
}
} // namespace mongo