SERVER-49561 Add resharding fields to config.collections

11 files changed, 131 insertions, 5 deletions

diff --git a/src/mongo/db/s/SConscript b/src/mongo/db/s/SConscript
index 1299619916c..12904d41747 100644
--- a/src/mongo/db/s/SConscript
+++ b/src/mongo/db/s/SConscript
@@ -87,7 +87,6 @@ env.Library(
         'start_chunk_clone_request.cpp',
         env.Idlc('migration_coordinator_document.idl')[0],
         env.Idlc('range_deletion_task.idl')[0],
-        env.Idlc('resharding/common_types.idl')[0],
         env.Idlc('resharding/coordinator_document.idl')[0],
         env.Idlc('resharding/donor_document.idl')[0],
         env.Idlc('resharding/recipient_document.idl')[0],
diff --git a/src/mongo/db/s/resharding/coordinator_document.idl b/src/mongo/db/s/resharding/coordinator_document.idl
index e1c97b1760f..761e55fb6b2 100644
--- a/src/mongo/db/s/resharding/coordinator_document.idl
+++ b/src/mongo/db/s/resharding/coordinator_document.idl
@@ -33,7 +33,7 @@ global:
     cpp_namespace: "mongo"
 
 imports:
-    - "mongo/db/s/resharding/common_types.idl"
+    - "mongo/s/resharding/common_types.idl"
 
 structs:
     DonorShardEntry:
diff --git a/src/mongo/db/s/resharding/donor_document.idl b/src/mongo/db/s/resharding/donor_document.idl
index 7716c7a77f8..7febc85192b 100644
--- a/src/mongo/db/s/resharding/donor_document.idl
+++ b/src/mongo/db/s/resharding/donor_document.idl
@@ -33,7 +33,7 @@ global:
     cpp_namespace: "mongo"
 
 imports:
-    - "mongo/db/s/resharding/common_types.idl"
+    - "mongo/s/resharding/common_types.idl"
 
 structs:
     ReshardingDonorDocument:
diff --git a/src/mongo/db/s/resharding/recipient_document.idl b/src/mongo/db/s/resharding/recipient_document.idl
index f3946c5cf1b..3040f2ad681 100644
--- a/src/mongo/db/s/resharding/recipient_document.idl
+++ b/src/mongo/db/s/resharding/recipient_document.idl
@@ -33,7 +33,7 @@ global:
     cpp_namespace: "mongo"
 
 imports:
-    - "mongo/db/s/resharding/common_types.idl"
+    - "mongo/s/resharding/common_types.idl"
 
 structs:
     DonorShardMirroringEntry:
diff --git a/src/mongo/s/SConscript b/src/mongo/s/SConscript
index 70400e57ed0..89b1572754d 100644
--- a/src/mongo/s/SConscript
+++ b/src/mongo/s/SConscript
@@ -181,6 +181,8 @@ env.Library(
         env.Idlc('request_types/reshard_collection.idl')[0],
         env.Idlc('resharded_chunk.idl')[0],
         env.Idlc('request_types/wait_for_fail_point.idl')[0],
+        env.Idlc('resharding/common_types.idl')[0],
+        env.Idlc('resharding/type_collection_fields.idl')[0],
     ],
     LIBDEPS=[
         '$BUILD_DIR/mongo/client/connection_string',
diff --git a/src/mongo/s/catalog/type_collection.cpp b/src/mongo/s/catalog/type_collection.cpp
index 3ff95150dfc..0141ecdc4a7 100644
--- a/src/mongo/s/catalog/type_collection.cpp
+++ b/src/mongo/s/catalog/type_collection.cpp
@@ -56,6 +56,7 @@ const BSONField<BSONObj> CollectionType::defaultCollation("defaultCollation");
 const BSONField<bool> CollectionType::unique("unique");
 const BSONField<UUID> CollectionType::uuid("uuid");
 const BSONField<std::string> CollectionType::distributionMode("distributionMode");
+const BSONField<ReshardingFields> CollectionType::reshardingFields("reshardingFields");
 
 StatusWith<CollectionType> CollectionType::fromBSON(const BSONObj& source) {
     CollectionType coll;
@@ -200,6 +201,15 @@ StatusWith<CollectionType> CollectionType::fromBSON(const BSONObj& source) {
         }
     }
 
+    {
+        const auto reshardingFieldsElem = source.getField(reshardingFields.name());
+        if (reshardingFieldsElem) {
+            coll._reshardingFields =
+                ReshardingFields::parse(IDLParserErrorContext("TypeCollectionReshardingFields"),
+                                        reshardingFieldsElem.Obj());
+        }
+    }
+
     return StatusWith<CollectionType>(coll);
 }
 
@@ -283,6 +293,10 @@ BSONObj CollectionType::toBSON() const {
         }
     }
 
+    if (_reshardingFields) {
+        builder.append(reshardingFields.name(), _reshardingFields->toBSON());
+    }
+
     return builder.obj();
 }
 
@@ -308,6 +322,10 @@ void CollectionType::setKeyPattern(const KeyPattern& keyPattern) {
     _keyPattern = keyPattern;
 }
 
+void CollectionType::setReshardingFields(const ReshardingFields& reshardingFields) {
+    _reshardingFields = reshardingFields;
+}
+
 bool CollectionType::hasSameOptions(const CollectionType& other) const {
     // The relevant options must have been set on this CollectionType.
     invariant(_fullNs && _keyPattern && _unique);
diff --git a/src/mongo/s/catalog/type_collection.h b/src/mongo/s/catalog/type_collection.h
index dd40380453f..47190ee216a 100644
--- a/src/mongo/s/catalog/type_collection.h
+++ b/src/mongo/s/catalog/type_collection.h
@@ -35,6 +35,7 @@
 #include "mongo/db/jsobj.h"
 #include "mongo/db/keypattern.h"
 #include "mongo/db/namespace_string.h"
+#include "mongo/s/resharding/type_collection_fields_gen.h"
 #include "mongo/util/uuid.h"
 
 namespace mongo {
@@ -43,6 +44,7 @@ class Status;
 template <typename T>
 class StatusWith;
 
+using ReshardingFields = TypeCollectionReshardingFields;
 
 /**
  * This class represents the layout and contents of documents contained in the config server's
@@ -65,6 +67,24 @@ class StatusWith;
  *      "uuid" : UUID,
  *      "noBalance" : false,
  *      "distributionMode" : "unsharded|sharded",
+ *      // Only populated if the collection is currently undergoing a resharding operation.
+ *      "reshardingFields" : {
+ *          "uuid" : UUID,
+ *          "state" : CoordinatorState<kInitialized>,
+ *          // Only populated if the collection is currently undergoing a resharding operation,
+ *          // and this collection is the original sharded collection.
+ *          "donorFields" : {
+ *              "reshardingKey" : {
+ *                  "_notTheID" : 1
+ *              }
+ *          },
+ *          // Only populated if this collection is the temporary resharding collection in a
+ *          // resharding operation.
+ *          "recipientFields" : {
+ *              "fetchTimestamp" : Timestamp(3, 4),
+ *              "originalNamespace" : "foo.bar",
+ *          }
+ *      }
  *   }
  *
  */
@@ -81,6 +101,7 @@ public:
     static const BSONField<bool> unique;
     static const BSONField<UUID> uuid;
     static const BSONField<std::string> distributionMode;
+    static const BSONField<ReshardingFields> reshardingFields;
 
     /**
      * Constructs a new CollectionType object from BSON. Also does validation of the contents.
@@ -173,6 +194,12 @@ public:
         return _distributionMode.get_value_or(DistributionMode::kSharded);
     }
 
+    void setReshardingFields(const ReshardingFields& reshardingFields);
+
+    boost::optional<ReshardingFields> getReshardingFields() const {
+        return _reshardingFields;
+    }
+
     bool hasSameOptions(const CollectionType& other) const;
 
 private:
@@ -206,6 +233,9 @@ private:
 
     // Optional whether balancing is allowed for this collection. If missing, implies true.
     boost::optional<bool> _allowBalance;
+
+    // Fields on the collection entry specific to resharding.
+    boost::optional<ReshardingFields> _reshardingFields;
 };
 
 }  // namespace mongo
diff --git a/src/mongo/s/catalog/type_collection_test.cpp b/src/mongo/s/catalog/type_collection_test.cpp
index 9b4c9367cb3..92b70442e9c 100644
--- a/src/mongo/s/catalog/type_collection_test.cpp
+++ b/src/mongo/s/catalog/type_collection_test.cpp
@@ -74,13 +74,19 @@ TEST(CollectionType, Basic) {
 TEST(CollectionType, AllFieldsPresent) {
     const OID oid = OID::gen();
     const auto uuid = UUID::gen();
+    const auto reshardingUuid = UUID::gen();
+
+    ReshardingFields reshardingFields;
+    reshardingFields.setUuid(reshardingUuid);
+
     StatusWith<CollectionType> status = CollectionType::fromBSON(BSON(
         CollectionType::fullNs("db.coll")
         << CollectionType::epoch(oid) << CollectionType::updatedAt(Date_t::fromMillisSinceEpoch(1))
         << CollectionType::keyPattern(BSON("a" << 1))
         << CollectionType::defaultCollation(BSON("locale"
                                                  << "fr_CA"))
-        << CollectionType::unique(true) << CollectionType::uuid() << uuid));
+        << CollectionType::unique(true) << CollectionType::uuid() << uuid
+        << CollectionType::reshardingFields() << reshardingFields.toBSON()));
     ASSERT_TRUE(status.isOK());
 
     CollectionType coll = status.getValue();
@@ -97,6 +103,8 @@ TEST(CollectionType, AllFieldsPresent) {
     ASSERT_EQUALS(coll.getDropped(), false);
     ASSERT_TRUE(coll.getUUID());
     ASSERT_EQUALS(*coll.getUUID(), uuid);
+    ASSERT(coll.getReshardingFields()->getState() == CoordinatorStateEnum::kUnused);
+    ASSERT(coll.getReshardingFields()->getUuid() == reshardingUuid);
 }
 
 TEST(CollectionType, EmptyDefaultCollationFailsToParse) {
diff --git a/src/mongo/db/s/resharding/common_types.idl b/src/mongo/s/resharding/common_types.idl
index 6eed708138e..6eed708138e 100644
--- a/src/mongo/db/s/resharding/common_types.idl
+++ b/src/mongo/s/resharding/common_types.idl
diff --git a/src/mongo/s/resharding/type_collection_fields.idl b/src/mongo/s/resharding/type_collection_fields.idl
new file mode 100644
index 00000000000..460a2111d35
--- /dev/null
+++ b/src/mongo/s/resharding/type_collection_fields.idl
@@ -0,0 +1,68 @@
+# Copyright (C) 2020-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.
+#
+
+# This file defines the format of resharding-related fields stored in a config.collections entry.
+
+global:
+    cpp_namespace: "mongo"
+
+imports:
+    - "mongo/db/keypattern.idl"
+    - "mongo/s/resharding/common_types.idl"
+
+structs:
+    TypeCollectionDonorFields:
+        description: "Resharding-related fields specific to donor shards."
+        fields:
+            reshardingKey:
+                type: KeyPattern
+
+    TypeCollectionRecipientFields:
+        description: "Resharding-related fields specific to recipient shards."
+        inline_chained_structs: true
+        chained_structs:
+            FetchTimestamp: FetchTimestampStruct
+        fields:
+            originalNamespace:
+                type: namespacestring
+
+    TypeCollectionReshardingFields:
+        description: "Resharding-related fields meant to be stored in a config.collections
+                      document."
+        fields:
+            uuid:
+                type: uuid
+            state:
+                type: CoordinatorState
+                default: kUnused
+            donorFields:
+                type: TypeCollectionDonorFields
+                optional: true
+            recipientFields:
+                type: TypeCollectionRecipientFields
+                optional: true
diff --git a/src/mongo/util/uuid.h b/src/mongo/util/uuid.h
index 4330eee758e..c5abb1cad7f 100644
--- a/src/mongo/util/uuid.h
+++ b/src/mongo/util/uuid.h
@@ -95,6 +95,7 @@ class UUID {
     friend class ShardsvrRenameCollection;
     friend class TenantMigrationDonorDocument;
     friend class TenantMigrationRecipientDocument;
+    friend class TypeCollectionReshardingFields;
     friend class VoteCommitIndexBuild;