SERVER-43120 SERVER-43121 SERVER-43122 ReadWriteConcernDefaults component, setDefaultRWConcern and getDefaultRWConcern commands, check RWC default suitability

1 files changed, 158 insertions, 0 deletions

diff --git a/src/mongo/db/read_write_concern_defaults.cpp b/src/mongo/db/read_write_concern_defaults.cpp
new file mode 100644
index 00000000000..828160e2e41
--- /dev/null
+++ b/src/mongo/db/read_write_concern_defaults.cpp
@@ -0,0 +1,158 @@
+/**
+ *    Copyright (C) 2019-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/read_write_concern_defaults.h"
+
+#include "mongo/db/logical_clock.h"
+
+namespace mongo {
+
+void ReadWriteConcernDefaults::checkSuitabilityAsDefault(const ReadConcern& rc) {
+    uassert(ErrorCodes::BadValue,
+            str::stream() << "level: '" << ReadConcern::kSnapshotReadConcernStr
+                          << "' is not suitable for the default read concern",
+            rc.getLevel() != repl::ReadConcernLevel::kSnapshotReadConcern);
+    uassert(ErrorCodes::BadValue,
+            str::stream() << "level: '" << ReadConcern::kLinearizableReadConcernStr
+                          << "' is not suitable for the default read concern",
+            rc.getLevel() != repl::ReadConcernLevel::kLinearizableReadConcern);
+    uassert(ErrorCodes::BadValue,
+            str::stream() << "'" << ReadConcern::kAfterOpTimeFieldName
+                          << "' is not suitable for the default read concern",
+            !rc.getArgsOpTime());
+    uassert(ErrorCodes::BadValue,
+            str::stream() << "'" << ReadConcern::kAfterClusterTimeFieldName
+                          << "' is not suitable for the default read concern",
+            !rc.getArgsAfterClusterTime());
+    uassert(ErrorCodes::BadValue,
+            str::stream() << "'" << ReadConcern::kAtClusterTimeFieldName
+                          << "' is not suitable for the default read concern",
+            !rc.getArgsAtClusterTime());
+}
+
+void ReadWriteConcernDefaults::checkSuitabilityAsDefault(const WriteConcern& wc) {
+    uassert(ErrorCodes::BadValue,
+            "Unacknowledged write concern is not suitable for the default write concern",
+            !(wc.wMode.empty() && wc.wNumNodes < 1));
+}
+
+void ReadWriteConcernDefaults::_setDefault(WithLock, RWConcernDefault&& rwc) {
+    _defaults.erase(kReadWriteConcernEntry);
+    _defaults.emplace(kReadWriteConcernEntry, rwc);
+}
+
+RWConcernDefault ReadWriteConcernDefaults::setConcerns(OperationContext* opCtx,
+                                                       const boost::optional<ReadConcern>& rc,
+                                                       const boost::optional<WriteConcern>& wc) {
+    invariant(rc || wc);
+
+    if (rc) {
+        checkSuitabilityAsDefault(*rc);
+    }
+    if (wc) {
+        checkSuitabilityAsDefault(*wc);
+    }
+
+    auto now = opCtx->getServiceContext()->getFastClockSource()->now();
+    auto epoch = LogicalClock::get(opCtx->getServiceContext())->getClusterTime().asTimestamp();
+
+    RWConcernDefault rwc;
+    rwc.setDefaultReadConcern(rc);
+    rwc.setDefaultWriteConcern(wc);
+    rwc.setEpoch(epoch);
+    rwc.setSetTime(now);
+    rwc.setLocalSetTime(now);
+
+    stdx::lock_guard<Latch> lk(_mutex);
+
+    auto current = _getDefault(lk);
+    if (!rc && current) {
+        rwc.setDefaultReadConcern(current->getDefaultReadConcern());
+    }
+    if (!wc && current) {
+        rwc.setDefaultWriteConcern(current->getDefaultWriteConcern());
+    }
+    _setDefault(lk, std::move(rwc));
+    return *_getDefault(lk);
+}
+
+void ReadWriteConcernDefaults::invalidate() {
+    stdx::lock_guard<Latch> lk(_mutex);
+    _defaults.erase(kReadWriteConcernEntry);
+}
+
+boost::optional<RWConcernDefault> ReadWriteConcernDefaults::_getDefault(WithLock) const {
+    if (_defaults.find(kReadWriteConcernEntry) == _defaults.end()) {
+        return boost::none;
+    }
+    return _defaults.at(kReadWriteConcernEntry);
+}
+
+RWConcernDefault ReadWriteConcernDefaults::getDefault() const {
+    auto current = ([&]() {
+        stdx::lock_guard<Latch> lk(_mutex);
+        return _getDefault(lk);
+    })();
+    if (!current) {
+        return RWConcernDefault{};
+    }
+    return *current;
+}
+
+boost::optional<ReadWriteConcernDefaults::ReadConcern>
+ReadWriteConcernDefaults::getDefaultReadConcern() const {
+    auto current = getDefault();
+    return current.getDefaultReadConcern();
+}
+
+boost::optional<ReadWriteConcernDefaults::WriteConcern>
+ReadWriteConcernDefaults::getDefaultWriteConcern() const {
+    auto current = getDefault();
+    return current.getDefaultWriteConcern();
+}
+
+
+namespace {
+
+const auto getReadWriteConcernDefaults =
+    ServiceContext::declareDecoration<ReadWriteConcernDefaults>();
+
+}  // namespace
+
+ReadWriteConcernDefaults& ReadWriteConcernDefaults::get(ServiceContext* service) {
+    return getReadWriteConcernDefaults(service);
+}
+
+ReadWriteConcernDefaults& ReadWriteConcernDefaults::get(ServiceContext& service) {
+    return getReadWriteConcernDefaults(service);
+}
+
+}  // namespace mongo