SERVER-62441 Define a new type mongo::TenantId for tenant id

1 files changed, 152 insertions, 0 deletions

diff --git a/src/mongo/db/tenant_id.h b/src/mongo/db/tenant_id.h
new file mode 100644
index 00000000000..7af08a45d95
--- /dev/null
+++ b/src/mongo/db/tenant_id.h
@@ -0,0 +1,152 @@
+/**
+ *    Copyright (C) 2022-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.
+ */
+
+#pragma once
+
+#include <ostream>
+#include <string>
+
+#include "mongo/base/string_data.h"
+#include "mongo/bson/bsonelement.h"
+#include "mongo/bson/bsonmisc.h"
+#include "mongo/bson/bsonobjbuilder.h"
+#include "mongo/bson/oid.h"
+#include "mongo/bson/util/builder.h"
+
+namespace mongo {
+
+/**
+ *  Representation of a tenant identifier.
+ */
+class TenantId {
+public:
+    /**
+     * kSystemTenantId must be unique across all possible tenant IDs.
+     * Since the first four bytes of an OID are a unix epoch timestamp,
+     * we can simply select a value prior to the inception of MongoDB,
+     * and be guaranteed to never have a collision with a value
+     * produced by OID::gen().
+     */
+    static const TenantId kSystemTenantId;
+
+    explicit TenantId(const OID& oid) : _oid(oid), _idStr(oid.toString()) {}
+
+    TenantId() = delete;
+
+    const std::string& toString() const {
+        return _idStr;
+    }
+
+    /**
+     * Returns -1, 0, or 1 if 'this' is less, equal, or greater than 'other' in
+     * lexicographical order.
+     */
+    int compare(const TenantId& other) const {
+        return _oid.compare(other._oid);
+    }
+
+    std::size_t hash() const {
+        return OID::Hasher()(_oid);
+    }
+
+    /**
+     * Functor compatible with std::hash for std::unordered_{map,set}
+     */
+    struct Hasher {
+        std::size_t operator()(const TenantId& tenantId) const {
+            return tenantId.hash();
+        }
+    };
+
+    /**
+     * Hash function compatible with absl::Hash for absl::unordered_{map,set}
+     */
+    template <typename H>
+    friend H AbslHashValue(H h, const TenantId& tenantId) {
+        return H::combine(std::move(h), tenantId.hash());
+    }
+
+    /**
+     * Parse tenant id from BSON. The function is used by IDL parsers.
+     */
+    static TenantId parseFromBSON(const BSONElement& elem);
+
+    /**
+     * Serialize tenant id to BSON. These functions are used by IDL parsers.
+     */
+    void serializeToBSON(StringData fieldName, BSONObjBuilder* builder) const;
+    void serializeToBSON(BSONArrayBuilder* builder) const;
+
+private:
+    OID _oid;
+    std::string _idStr;
+};
+
+inline bool operator==(const TenantId& lhs, const TenantId& rhs) {
+    return lhs.compare(rhs) == 0;
+}
+
+inline bool operator!=(const TenantId& lhs, const TenantId& rhs) {
+    return !(lhs == rhs);
+}
+
+inline bool operator<(const TenantId& lhs, const TenantId& rhs) {
+    return lhs.compare(rhs) < 0;
+}
+
+inline bool operator>(const TenantId& lhs, const TenantId& rhs) {
+    return rhs < lhs;
+}
+
+inline bool operator<=(const TenantId& lhs, const TenantId& rhs) {
+    return !(lhs > rhs);
+}
+
+inline bool operator>=(const TenantId& lhs, const TenantId& rhs) {
+    return !(lhs < rhs);
+}
+
+inline std::ostream& operator<<(std::ostream& os, const TenantId& tenantId) {
+    return os << tenantId.toString();
+}
+
+template <typename Allocator>
+StringBuilderImpl<Allocator>& operator<<(StringBuilderImpl<Allocator>& stream,
+                                         const TenantId& tenantId) {
+    return stream << tenantId.toString();
+}
+
+/**
+ * Supports use of TenantId with the BSON macro:
+ *     BSON("tenant" << tenantId)
+ */
+template <>
+BSONObjBuilder& BSONObjBuilderValueStream::operator<<<TenantId>(TenantId value);
+
+}  // namespace mongo