SERVER-58466 Minor optimization on the CatalogCache

10 files changed, 58 insertions, 43 deletions

diff --git a/src/mongo/db/s/balancer/balance_stats_test.cpp b/src/mongo/db/s/balancer/balance_stats_test.cpp
index a4c2f2b00bf..9381e0a2da6 100644
--- a/src/mongo/db/s/balancer/balance_stats_test.cpp
+++ b/src/mongo/db/s/balancer/balance_stats_test.cpp
@@ -67,7 +67,8 @@ public:
 
         return ChunkManager(_shardPrimary,
                             _dbVersion,
-                            RoutingTableHistoryValueHandle(std::move(routingTableHistory)),
+                            RoutingTableHistoryValueHandle(std::make_shared<RoutingTableHistory>(
+                                std::move(routingTableHistory))),
                             boost::none);
     }
 
diff --git a/src/mongo/db/s/resharding/resharding_data_replication_test.cpp b/src/mongo/db/s/resharding/resharding_data_replication_test.cpp
index b33c3487be9..9be48c3c59d 100644
--- a/src/mongo/db/s/resharding/resharding_data_replication_test.cpp
+++ b/src/mongo/db/s/resharding/resharding_data_replication_test.cpp
@@ -102,7 +102,8 @@ private:
     RoutingTableHistoryValueHandle makeStandaloneRoutingTableHistory(RoutingTableHistory rt) {
         const auto version = rt.getVersion();
         return RoutingTableHistoryValueHandle(
-            std::move(rt), ComparableChunkVersion::makeComparableChunkVersion(version));
+            std::make_shared<RoutingTableHistory>(std::move(rt)),
+            ComparableChunkVersion::makeComparableChunkVersion(version));
     }
 
     const StringData _currentShardKey = "sk";
diff --git a/src/mongo/db/s/resharding/resharding_oplog_batch_applier_test.cpp b/src/mongo/db/s/resharding/resharding_oplog_batch_applier_test.cpp
index c72b4a2122a..2e741189743 100644
--- a/src/mongo/db/s/resharding/resharding_oplog_batch_applier_test.cpp
+++ b/src/mongo/db/s/resharding/resharding_oplog_batch_applier_test.cpp
@@ -324,7 +324,8 @@ private:
     RoutingTableHistoryValueHandle makeStandaloneRoutingTableHistory(RoutingTableHistory rt) {
         const auto version = rt.getVersion();
         return RoutingTableHistoryValueHandle(
-            std::move(rt), ComparableChunkVersion::makeComparableChunkVersion(version));
+            std::make_shared<RoutingTableHistory>(std::move(rt)),
+            ComparableChunkVersion::makeComparableChunkVersion(version));
     }
 
     const StringData _currentShardKey = "sk";
diff --git a/src/mongo/db/s/resharding/resharding_oplog_crud_application_test.cpp b/src/mongo/db/s/resharding/resharding_oplog_crud_application_test.cpp
index 4be2c87a008..ad8df37a2b8 100644
--- a/src/mongo/db/s/resharding/resharding_oplog_crud_application_test.cpp
+++ b/src/mongo/db/s/resharding/resharding_oplog_crud_application_test.cpp
@@ -311,7 +311,8 @@ private:
     RoutingTableHistoryValueHandle makeStandaloneRoutingTableHistory(RoutingTableHistory rt) {
         const auto version = rt.getVersion();
         return RoutingTableHistoryValueHandle(
-            std::move(rt), ComparableChunkVersion::makeComparableChunkVersion(version));
+            std::make_shared<RoutingTableHistory>(std::move(rt)),
+            ComparableChunkVersion::makeComparableChunkVersion(version));
     }
 
     const StringData _currentShardKey = "sk";
diff --git a/src/mongo/db/s/resharding/resharding_recipient_service_test.cpp b/src/mongo/db/s/resharding/resharding_recipient_service_test.cpp
index 5ec1423036c..5d69b790321 100644
--- a/src/mongo/db/s/resharding/resharding_recipient_service_test.cpp
+++ b/src/mongo/db/s/resharding/resharding_recipient_service_test.cpp
@@ -139,7 +139,8 @@ private:
     RoutingTableHistoryValueHandle _makeStandaloneRoutingTableHistory(RoutingTableHistory rt) {
         const auto version = rt.getVersion();
         return RoutingTableHistoryValueHandle(
-            std::move(rt), ComparableChunkVersion::makeComparableChunkVersion(version));
+            std::make_shared<RoutingTableHistory>(std::move(rt)),
+            ComparableChunkVersion::makeComparableChunkVersion(version));
     }
 
     const StringData _currentShardKey = "oldKey";
diff --git a/src/mongo/db/s/sharding_write_router_bm.cpp b/src/mongo/db/s/sharding_write_router_bm.cpp
index 8d354b1198c..d090a015946 100644
--- a/src/mongo/db/s/sharding_write_router_bm.cpp
+++ b/src/mongo/db/s/sharding_write_router_bm.cpp
@@ -81,7 +81,8 @@ ChunkRange getRangeForChunk(int i, int nChunks) {
 RoutingTableHistoryValueHandle makeStandaloneRoutingTableHistory(RoutingTableHistory rt) {
     const auto version = rt.getVersion();
     return RoutingTableHistoryValueHandle(
-        std::move(rt), ComparableChunkVersion::makeComparableChunkVersion(version));
+        std::make_shared<RoutingTableHistory>(std::move(rt)),
+        ComparableChunkVersion::makeComparableChunkVersion(version));
 }
 
 std::pair<std::vector<mongo::ChunkType>, mongo::ChunkManager> createChunks(
diff --git a/src/mongo/s/catalog_cache.cpp b/src/mongo/s/catalog_cache.cpp
index 933ecbd0df1..9e3eea4a5a4 100644
--- a/src/mongo/s/catalog_cache.cpp
+++ b/src/mongo/s/catalog_cache.cpp
@@ -654,6 +654,43 @@ CatalogCache::CollectionCache::LookupResult CatalogCache::CollectionCache::_look
 
         auto collectionAndChunks = _catalogCacheLoader.getChunksSince(nss, lookupVersion).get();
 
+        // If a refresh doesn't find new information -> re-use the existing RoutingTableHistory
+        if (isIncremental && collectionAndChunks.changedChunks.size() == 1 &&
+            collectionAndChunks.changedChunks[0].getVersion() ==
+                existingHistory->optRt->getVersion()) {
+
+            invariant(
+                collectionAndChunks.allowMigrations == existingHistory->optRt->allowMigrations(),
+                str::stream() << "allowMigrations field of " << nss
+                              << " collection changed without changing the collection version "
+                              << existingHistory->optRt->getVersion().toString()
+                              << ". Old value: " << existingHistory->optRt->allowMigrations()
+                              << ", new value: " << collectionAndChunks.allowMigrations);
+
+
+            const auto& oldReshardingFields = existingHistory->optRt->getReshardingFields();
+            const auto& newReshardingFields = collectionAndChunks.reshardingFields;
+
+            invariant(
+                [&] {
+                    if (oldReshardingFields && newReshardingFields)
+                        return oldReshardingFields->toBSON().woCompare(
+                                   newReshardingFields->toBSON()) == 0;
+                    else
+                        return !oldReshardingFields && !newReshardingFields;
+                }(),
+                str::stream() << "reshardingFields field of " << nss
+                              << " collection changed without changing the collection version "
+                              << existingHistory->optRt->getVersion().toString()
+                              << ". Old value: " << oldReshardingFields->toBSON()
+                              << ", new value: " << newReshardingFields->toBSON());
+
+            // Despite we didn't find new info, we must update the time of this entry on the cache
+            newComparableVersion.setChunkVersion(collectionAndChunks.changedChunks[0].getVersion());
+            return LookupResult(OptionalRoutingTableHistory(existingHistory->optRt),
+                                std::move(newComparableVersion));
+        }
+
         const auto maxChunkSize = [&]() -> boost::optional<uint64_t> {
             if (!collectionAndChunks.allowAutoSplit) {
                 // maxChunkSize = 0 is an invalid chunkSize so we use it to detect noAutoSplit
@@ -715,27 +752,8 @@ CatalogCache::CollectionCache::LookupResult CatalogCache::CollectionCache::_look
         }
 
         const ChunkVersion newVersion = newRoutingHistory.getVersion();
-
         newComparableVersion.setChunkVersion(newVersion);
 
-        if (isIncremental && existingHistory->optRt->getVersion() == newVersion) {
-            invariant(newRoutingHistory.sameAllowMigrations(*existingHistory->optRt),
-                      str::stream()
-                          << "allowMigrations field of " << nss
-                          << " collection changed without changing the collection version "
-                          << newVersion.toString()
-                          << ". Old value: " << existingHistory->optRt->allowMigrations()
-                          << ", new value: " << newRoutingHistory.allowMigrations());
-
-            invariant(newRoutingHistory.sameReshardingFields(*existingHistory->optRt),
-                      str::stream()
-                          << "reshardingFields field of " << nss
-                          << " collection changed without changing the collection version "
-                          << newVersion.toString() << ". Old value: "
-                          << existingHistory->optRt->getReshardingFields()->toBSON()
-                          << ", new value: " << newRoutingHistory.getReshardingFields()->toBSON());
-        }
-
         LOGV2_FOR_CATALOG_REFRESH(4619901,
                                   isIncremental || newComparableVersion != previousVersion ? 0 : 1,
                                   "Refreshed cached collection",
@@ -746,7 +764,8 @@ CatalogCache::CollectionCache::LookupResult CatalogCache::CollectionCache::_look
                                   "duration"_attr = Milliseconds(t.millis()));
         _updateRefreshesStats(isIncremental, false);
 
-        return LookupResult(OptionalRoutingTableHistory(std::move(newRoutingHistory)),
+        return LookupResult(OptionalRoutingTableHistory(std::make_shared<RoutingTableHistory>(
+                                std::move(newRoutingHistory))),
                             std::move(newComparableVersion));
     } catch (const DBException& ex) {
         _stats.countFailedRefreshes.addAndFetch(1);
diff --git a/src/mongo/s/chunk_manager.h b/src/mongo/s/chunk_manager.h
index 9d48ccfb9eb..dca4d973ace 100644
--- a/src/mongo/s/chunk_manager.h
+++ b/src/mongo/s/chunk_manager.h
@@ -290,18 +290,6 @@ public:
         return _uuid && *_uuid == uuid;
     }
 
-    bool sameAllowMigrations(const RoutingTableHistory& other) const {
-        return _allowMigrations == other._allowMigrations;
-    }
-
-    bool sameReshardingFields(const RoutingTableHistory& other) const {
-        if (_reshardingFields && other._reshardingFields) {
-            return _reshardingFields->toBSON().woCompare(other._reshardingFields->toBSON()) == 0;
-        } else {
-            return !_reshardingFields && !other._reshardingFields;
-        }
-    }
-
     boost::optional<UUID> getUUID() const {
         return _uuid;
     }
@@ -484,10 +472,10 @@ struct OptionalRoutingTableHistory {
     OptionalRoutingTableHistory() = default;
 
     // SHARDED collection constructor
-    OptionalRoutingTableHistory(RoutingTableHistory&& rt) : optRt(std::move(rt)) {}
+    OptionalRoutingTableHistory(std::shared_ptr<RoutingTableHistory> rt) : optRt(std::move(rt)) {}
 
-    // If boost::none, the collection is UNSHARDED, otherwise it is SHARDED
-    boost::optional<RoutingTableHistory> optRt;
+    // If nullptr, the collection is UNSHARDED, otherwise it is SHARDED
+    std::shared_ptr<RoutingTableHistory> optRt;
 };
 
 using RoutingTableHistoryCache =
diff --git a/src/mongo/s/chunk_manager_refresh_bm.cpp b/src/mongo/s/chunk_manager_refresh_bm.cpp
index 611b7826c7c..4aec67285e1 100644
--- a/src/mongo/s/chunk_manager_refresh_bm.cpp
+++ b/src/mongo/s/chunk_manager_refresh_bm.cpp
@@ -46,7 +46,8 @@ const NamespaceString kNss("test", "foo");
 RoutingTableHistoryValueHandle makeStandaloneRoutingTableHistory(RoutingTableHistory rt) {
     const auto version = rt.getVersion();
     return RoutingTableHistoryValueHandle(
-        std::move(rt), ComparableChunkVersion::makeComparableChunkVersion(version));
+        std::make_shared<RoutingTableHistory>(std::move(rt)),
+        ComparableChunkVersion::makeComparableChunkVersion(version));
 }
 
 ChunkRange getRangeForChunk(int i, int nChunks) {
diff --git a/src/mongo/s/sharding_test_fixture_common.cpp b/src/mongo/s/sharding_test_fixture_common.cpp
index 12ef4fd5006..f136cadc42c 100644
--- a/src/mongo/s/sharding_test_fixture_common.cpp
+++ b/src/mongo/s/sharding_test_fixture_common.cpp
@@ -68,7 +68,8 @@ RoutingTableHistoryValueHandle ShardingTestFixtureCommon::makeStandaloneRoutingT
     RoutingTableHistory rt) {
     const auto version = rt.getVersion();
     return RoutingTableHistoryValueHandle(
-        std::move(rt), ComparableChunkVersion::makeComparableChunkVersion(version));
+        std::make_shared<RoutingTableHistory>(std::move(rt)),
+        ComparableChunkVersion::makeComparableChunkVersion(version));
 }
 
 void ShardingTestFixtureCommon::onCommand(NetworkTestEnv::OnCommandFunction func) {