From db2e46857ce1c2bf90fda9842287cc5940fce81c Mon Sep 17 00:00:00 2001
From: Max Hirschhorn <max.hirschhorn@mongodb.com>
Date: Mon, 8 Mar 2021 22:37:40 +0000
Subject: SERVER-54980 Split donor and recipent documents into im/mutable
 state.

Removes the unused strictConsistencyTimestamp field from the recipient
document.

Also explicitly sets strict:true and strict:false for all of
resharding's IDL types.
---
 .../db/s/resharding/resharding_recipient_service.h | 38 +++++++++++++++-------
 1 file changed, 26 insertions(+), 12 deletions(-)

(limited to 'src/mongo/db/s/resharding/resharding_recipient_service.h')

diff --git a/src/mongo/db/s/resharding/resharding_recipient_service.h b/src/mongo/db/s/resharding/resharding_recipient_service.h
index 59e41df7b63..a5fab606b8b 100644
--- a/src/mongo/db/s/resharding/resharding_recipient_service.h
+++ b/src/mongo/db/s/resharding/resharding_recipient_service.h
@@ -133,6 +133,8 @@ public:
                                     const ReshardingRecipientDocument& recipientDoc);
 
 private:
+    RecipientStateMachine(const ReshardingRecipientDocument& recipientDoc);
+
     // The following functions correspond to the actions to take at a particular recipient state.
     ExecutorFuture<void> _awaitAllDonorsPreparedToDonateThenTransitionToCreatingCollection(
         const std::shared_ptr<executor::ScopedTaskExecutor>& executor);
@@ -153,17 +155,26 @@ private:
 
     void _renameTemporaryReshardingCollection();
 
-    // Transitions the state on-disk and in-memory to 'endState'.
-    void _transitionState(RecipientStateEnum endState,
-                          boost::optional<Timestamp> fetchTimestamp = boost::none,
-                          boost::optional<Status> abortReason = boost::none);
+    // Transitions the on-disk and in-memory state to 'newState'.
+    void _transitionState(RecipientStateEnum newState);
+
+    void _transitionState(RecipientShardContext&& newRecipientCtx,
+                          boost::optional<Timestamp>&& fetchTimestamp);
+
+    // Transitions the on-disk and in-memory state to RecipientStateEnum::kCreatingCollection.
+    void _transitionToCreatingCollection(Timestamp fetchTimestamp);
+
+    // Transitions the on-disk and in-memory state to RecipientStateEnum::kError.
+    void _transitionToError(Status abortReason);
 
     void _updateCoordinator();
 
-    // Updates the recipient document on-disk and in-memory with the 'replacementDoc.'
-    void _updateRecipientDocument(ReshardingRecipientDocument&& replacementDoc);
+    // Updates the mutable portion of the on-disk and in-memory recipient document with
+    // 'newRecipientCtx' and 'fetchTimestamp'.
+    void _updateRecipientDocument(RecipientShardContext&& newRecipientCtx,
+                                  boost::optional<Timestamp>&& fetchTimestamp);
 
-    // Removes the local recipient document from disk and clears the in-memory state.
+    // Removes the local recipient document from disk.
     void _removeRecipientDocument();
 
     // Removes any docs from the oplog applier progress and txn applier progress collections that
@@ -180,12 +191,15 @@ private:
     // (abort resharding).
     void _onAbortOrStepdown(WithLock, Status status);
 
-    // The in-memory representation of the underlying document in
+    // The in-memory representation of the immutable portion of the document in
     // config.localReshardingOperations.recipient.
-    ReshardingRecipientDocument _recipientDoc;
+    const CommonReshardingMetadata _metadata;
+    const std::vector<ShardId> _donorShardIds;
 
-    // The id both for the resharding operation and for the primary-only-service instance.
-    const UUID _id;
+    // The in-memory representation of the mutable portion of the document in
+    // config.localReshardingOperations.recipient.
+    RecipientShardContext _recipientCtx;
+    boost::optional<Timestamp> _fetchTimestamp;
 
     std::unique_ptr<ReshardingCollectionCloner> _collectionCloner;
     std::vector<std::unique_ptr<ReshardingTxnCloner>> _txnCloners;
@@ -200,7 +214,7 @@ private:
     std::vector<ExecutorFuture<void>> _oplogFetcherFutures;
 
     // Protects the promises below
-    Mutex _mutex = MONGO_MAKE_LATCH("ReshardingRecipient::_mutex");
+    Mutex _mutex = MONGO_MAKE_LATCH("RecipientStateMachine::_mutex");
 
     boost::optional<ReshardingCriticalSection> _critSec;
 
-- 
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