SERVER-24563 Fix race in check for DB names that differ in case only

(cherry picked from commit dceaf6bf28fb879eb23f3c022647ee3e8f15c370)

Modifications for backport:
        src/mongo/db/catalog/database_holder.h
        src/mongo/db/catalog/database_holder.cpp
        jstests/concurrency/fsm_all_sharded_replication.js
        jstests/concurrency/fsm_all_sharded_replication_with_balancer.js
        jstests/concurrency/fsm_workloads/create_database.js

3 files changed, 142 insertions, 0 deletions

diff --git a/jstests/concurrency/fsm_all_sharded_replication.js b/jstests/concurrency/fsm_all_sharded_replication.js
index d4068148d47..435277a2a47 100644
--- a/jstests/concurrency/fsm_all_sharded_replication.js
+++ b/jstests/concurrency/fsm_all_sharded_replication.js
@@ -9,6 +9,7 @@ var blacklist = [
     'distinct.js',             // SERVER-13116 distinct isn't sharding aware
     'distinct_noindex.js',     // SERVER-13116 distinct isn't sharding aware
     'distinct_projection.js',  // SERVER-13116 distinct isn't sharding aware
+    'create_database.js',      // SERVER-17397 Drops of sharded namespaces may not fully succeed
     'drop_database.js',        // SERVER-17397 Drops of sharded namespaces may not fully succeed
 
     // Disabled due to SERVER-3645, '.count() can be wrong on sharded collections'.
diff --git a/jstests/concurrency/fsm_all_sharded_replication_with_balancer.js b/jstests/concurrency/fsm_all_sharded_replication_with_balancer.js
index 444f7eab3cb..59d6e0f4a61 100644
--- a/jstests/concurrency/fsm_all_sharded_replication_with_balancer.js
+++ b/jstests/concurrency/fsm_all_sharded_replication_with_balancer.js
@@ -9,6 +9,7 @@ var blacklist = [
     'distinct.js',             // SERVER-13116 distinct isn't sharding aware
     'distinct_noindex.js',     // SERVER-13116 distinct isn't sharding aware
     'distinct_projection.js',  // SERVER-13116 distinct isn't sharding aware
+    'create_database.js',      // SERVER-17397 Drops of sharded namespaces may not fully succeed
     'drop_database.js',        // SERVER-17397 Drops of sharded namespaces may not fully succeed
     'remove_where.js',  // SERVER-14669 Multi-removes that use $where miscount removed documents
 
diff --git a/jstests/concurrency/fsm_workloads/create_database.js b/jstests/concurrency/fsm_workloads/create_database.js
new file mode 100644
index 00000000000..10b619454b4
--- /dev/null
+++ b/jstests/concurrency/fsm_workloads/create_database.js
@@ -0,0 +1,140 @@
+'use strict';
+
+/**
+ * create_database.js
+ *
+ * Repeatedly creates and drops a database, with the focus on creation using different name casing.
+ * Create using all different methods, implicitly by inserting, creating views/indexes etc.
+ *
+ * Each thread uses its own database, though sometimes threads may try to create databases with
+ * names that only differ in case, expecting the appriopriate error code.
+ */
+var $config = (function() {
+
+    var data = {
+        checkCommandResult: function checkCommandResult(mayFailWithDatabaseDifferCase, res) {
+            if (mayFailWithDatabaseDifferCase && !res.ok)
+                assertAlways.commandFailedWithCode(res, ErrorCodes.DatabaseDifferCase);
+            else
+                assertAlways.commandWorked(res);
+            return res;
+        },
+
+        checkWriteResult: function checkWriteResult(mayFailWithDatabaseDifferCase, res) {
+            if (mayFailWithDatabaseDifferCase && res.hasWriteError()) {
+                assertAlways.eq(res.getWriteError().code, ErrorCodes.DatabaseDifferCase);
+            } else
+                assertAlways.writeOK(res);
+            return res;
+        }
+    };
+
+    var states = (function() {
+        function init(db, collName) {
+            var uniqueNr = this.tid;
+            var semiUniqueNr = Math.floor(uniqueNr / 2);
+
+            // The semiUniqueDBName may clash and result in a DatabaseDifferCas error on
+            // creation,
+            // while the uniqueDBName does not clash. The unique and created variables track
+            // this.
+            this.semiUniqueDBName =
+                (this.tid % 2 ? 'create_database' : 'CREATE_DATABASE') + semiUniqueNr;
+            this.uniqueDBName = 'CreateDatabase' + uniqueNr;
+            this.myDB = db.getSiblingDB(this.uniqueDBName);
+            this.created = false;
+            this.unique = true;
+        }
+
+        function useSemiUniqueDBName(db, collName) {
+            this.myDB = db.getSiblingDB(this.semiUniqueDBName);
+            this.unique = false;
+        }
+
+        function createCollection(db, collName) {
+            this.created =
+                this.checkCommandResult(!this.unique, this.myDB.createCollection(collName)).ok;
+        }
+
+        function createIndex(db, collName) {
+            var background = Math.random > 0.5;
+            var res = this.myDB.getCollection(collName).createIndex({x: 1}, {background});
+            this.created |=
+                this.checkCommandResult(!this.unique, res).createdCollectionAutomatically;
+        }
+
+        function insert(db, collName) {
+            this.created |= this.checkWriteResult(!this.created && !this.unique,
+                                                  this.myDB.getCollection(collName).insert({x: 1}))
+                                .nInserted == 1;
+        }
+
+        function upsert(db, collName) {
+            this.created |= this.checkWriteResult(!this.created && !this.unique,
+                                                  this.myDB.getCollection(collName).update(
+                                                      {x: 1}, {x: 2}, {upsert: 1})).nUpserted == 1;
+        }
+
+        function drop(db, collName) {
+            if (this.created)
+                assertAlways(this.myDB.getCollection(collName).drop());
+        }
+
+        function dropDatabase(db, collName) {
+            if (this.created)
+                assertAlways.commandWorked(this.myDB.dropDatabase());
+        }
+
+        function listDatabases(db, collName) {
+            for (var database of db.adminCommand({listDatabases: 1}).databases) {
+                var res = db.getSiblingDB(database.name).runCommand({listCollections: 1});
+                assertAlways.commandWorked(res);
+                assertAlways.neq(database.name, this.myDB.toString(), "this DB shouldn't exist");
+            }
+        }
+
+        return {
+            init: init,
+            useSemiUniqueDBName: useSemiUniqueDBName,
+            createCollection: createCollection,
+            createIndex: createIndex,
+            insert: insert,
+            upsert: upsert,
+            drop: drop,
+            dropDatabase: dropDatabase,
+            listDatabases: listDatabases,
+        };
+    })();
+
+    var transitions = {
+        init: {
+            useSemiUniqueDBName: 0.25,
+            createCollection: 0.375,
+            createIndex: 0.125,
+            insert: 0.125,
+            upsert: 0.125
+        },
+        useSemiUniqueDBName: {createCollection: 1.00},
+        createCollection: {dropDatabase: 0.25, createIndex: 0.25, insert: 0.25, upsert: 0.25},
+        createIndex: {insert: 0.25, upsert: 0.25, dropDatabase: 0.5},
+        insert: {dropDatabase: 0.2, drop: 0.05, insert: 0.5, upsert: 0.25},
+        upsert: {dropDatabase: 0.2, drop: 0.05, insert: 0.25, upsert: 0.5},
+        drop: {dropDatabase: 0.75, init: 0.25},  // OK to leave the empty database behind sometimes
+        dropDatabase: {init: 0.75, listDatabases: 0.25},
+        listDatabases: {init: 0.75, listDatabases: 0.25},
+    };
+
+    return {
+        data: data,
+        // We only run a few iterations to reduce the amount of data cumulatively
+        // written to disk by mmapv1. For example, setting 10 threads and 180
+        // iterations (with an expected 6 transitions per create/drop roundtrip)
+        // causes this workload to write at least 32MB (.ns and .0 files) * 10 threads
+        // * 30 iterations worth of data to disk, or about 10GB, which can be slow on
+        // test hosts.
+        threadCount: 10,
+        iterations: 180,
+        states: states,
+        transitions: transitions,
+    };
+})();