SERVER-83485 Fix multikey-path serialization code used during validation

Author: dhly-etc

src/mongo/db/catalog/collection_validation.cpp

@@ -456,35 +456,6 @@ void addErrorIfUnequal(boost::optional<ValidationActionEnum> stored,
                       results);
 }
 
-std::string multikeyPathsToString(MultikeyPaths paths) {
-    str::stream builder;
-    builder << "[";
-    auto pathIt = paths.begin();
-    while (true) {
-        builder << "{";
-
-        auto pathSet = *pathIt;
-        auto setIt = pathSet.begin();
-        while (true) {
-            builder << *setIt++;
-            if (setIt == pathSet.end()) {
-                break;
-            } else {
-                builder << ",";
-            }
-        }
-        builder << "}";
-
-        if (++pathIt == paths.end()) {
-            break;
-        } else {
-            builder << ",";
-        }
-    }
-    builder << "]";
-    return builder;
-}
-
 void _validateCatalogEntry(OperationContext* opCtx,
                            ValidateState* validateState,
                            ValidateResults* results) {

src/mongo/db/index/SConscript

@@ -49,6 +49,7 @@ iamEnv.Library(
         'index_build_interceptor.cpp',
         'index_build_interceptor.idl',
         'index_descriptor.cpp',
+        'multikey_paths.cpp',
         's2_access_method.cpp',
         's2_bucket_access_method.cpp',
         'skipped_record_tracker.cpp',
@@ -125,6 +126,7 @@ indexTestEnv.CppUnitTest(
         'columns_access_method_test.cpp',
         'hash_key_generator_test.cpp',
         'index_build_interceptor_test.cpp',
+        'multikey_paths_test.cpp',
         's2_key_generator_test.cpp',
         's2_bucket_key_generator_test.cpp',
         'sort_key_generator_test.cpp',

src/mongo/db/index/multikey_paths.cpp

@@ -0,0 +1,74 @@
+/**
+ *    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/db/index/multikey_paths.h"
+
+#include "mongo/util/str.h"
+
+namespace mongo {
+
+std::string multikeyPathsToString(MultikeyPaths paths) {
+    str::stream builder;
+    builder << "[";
+    auto pathIt = paths.begin();
+    while (true) {
+        if (pathIt == paths.end()) {
+            break;
+        }
+
+        builder << "{";
+
+        auto pathSet = *pathIt;
+        auto setIt = pathSet.begin();
+        while (true) {
+            if (setIt == pathSet.end()) {
+                break;
+            }
+
+            builder << *setIt;
+            if (++setIt == pathSet.end()) {
+                break;
+            } else {
+                builder << ",";
+            }
+        }
+
+        builder << "}";
+
+        if (++pathIt == paths.end()) {
+            break;
+        } else {
+            builder << ",";
+        }
+    }
+    builder << "]";
+    return builder;
+}
+
+}  // namespace mongo

src/mongo/db/index/multikey_paths.h

@@ -67,4 +67,5 @@ using MultikeyComponents = boost::container::flat_set<
 constexpr std::size_t kFewCompoundIndexFields = 4;
 using MultikeyPaths = boost::container::small_vector<MultikeyComponents, kFewCompoundIndexFields>;
 
+std::string multikeyPathsToString(MultikeyPaths paths);
 }  // namespace mongo

src/mongo/db/index/multikey_paths_test.cpp

@@ -0,0 +1,74 @@
+/**
+ *    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/index/multikey_paths.h"
+#include "mongo/unittest/assert.h"
+#include "mongo/unittest/framework.h"
+
+#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kTest
+
+namespace mongo {
+namespace {
+
+TEST(MultikeyPaths, PrintEmptyPaths) {
+    MultikeyPaths paths;
+    ASSERT_EQ(multikeyPathsToString(paths), "[]");
+}
+
+TEST(MultikeyPaths, PrintEmptySetPaths) {
+    MultikeyPaths paths;
+    paths.resize(1);
+    ASSERT_EQ(multikeyPathsToString(paths), "[{}]");
+}
+
+TEST(MultikeyPaths, PrintEmptySetsPaths) {
+    MultikeyPaths paths;
+    paths.resize(2);
+    ASSERT_EQ(multikeyPathsToString(paths), "[{},{}]");
+}
+
+TEST(MultikeyPaths, PrintNonEmptySetPaths) {
+    MultikeyPaths paths;
+    paths.resize(2);
+    paths[1].insert(2);
+    ASSERT_EQ(multikeyPathsToString(paths), "[{},{2}]");
+}
+
+TEST(MultikeyPaths, PrintNonEmptySetsPaths) {
+    MultikeyPaths paths;
+    paths.resize(4);
+    paths[1].insert(2);
+    paths[3].insert(0);
+    paths[3].insert(1);
+    paths[3].insert(2);
+    ASSERT_EQ(multikeyPathsToString(paths), "[{},{2},{},{0,1,2}]");
+}
+
+}  // namespace
+}  // namespace mongo