SERVER-27382 Get rid of DBConfig::getChunkManagerOrPrimary

(cherry picked from commit 7f71474649f01b8914b4284be44cbe325c1458d0)

5 files changed, 36 insertions, 91 deletions

diff --git a/src/mongo/s/chunk_manager_targeter.cpp b/src/mongo/s/chunk_manager_targeter.cpp
index d8304521175..7771fa31db5 100644
--- a/src/mongo/s/chunk_manager_targeter.cpp
+++ b/src/mongo/s/chunk_manager_targeter.cpp
@@ -289,13 +289,14 @@ ChunkManagerTargeter::ChunkManagerTargeter(const NamespaceString& nss, TargeterS
 
 
 Status ChunkManagerTargeter::init(OperationContext* txn) {
-    auto dbStatus = ScopedShardDatabase::getOrCreate(txn, _nss.db());
-    if (!dbStatus.isOK()) {
-        return dbStatus.getStatus();
+    auto scopedCMStatus = ScopedChunkManager::getOrCreate(txn, _nss);
+    if (!scopedCMStatus.isOK()) {
+        return scopedCMStatus.getStatus();
     }
 
-    auto scopedDb = std::move(dbStatus.getValue());
-    scopedDb.db()->getChunkManagerOrPrimary(txn, _nss.ns(), _manager, _primary);
+    const auto& scopedCM = scopedCMStatus.getValue();
+    _manager = scopedCM.cm();
+    _primary = scopedCM.primary();
 
     return Status::OK();
 }
@@ -702,13 +703,14 @@ Status ChunkManagerTargeter::refreshIfNeeded(OperationContext* txn, bool* wasCha
     shared_ptr<ChunkManager> lastManager = _manager;
     shared_ptr<Shard> lastPrimary = _primary;
 
-    auto dbStatus = ScopedShardDatabase::getOrCreate(txn, _nss.db());
-    if (!dbStatus.isOK()) {
-        return dbStatus.getStatus();
+    auto scopedCMStatus = ScopedChunkManager::getOrCreate(txn, _nss);
+    if (!scopedCMStatus.isOK()) {
+        return scopedCMStatus.getStatus();
     }
 
-    auto scopedDb = std::move(dbStatus.getValue());
-    scopedDb.db()->getChunkManagerOrPrimary(txn, _nss.ns(), _manager, _primary);
+    const auto& scopedCM = scopedCMStatus.getValue();
+    _manager = scopedCM.cm();
+    _primary = scopedCM.primary();
 
     // We now have the latest metadata from the cache.
 
@@ -770,25 +772,17 @@ Status ChunkManagerTargeter::refreshNow(OperationContext* txn, RefreshType refre
     // Try not to spam the configs
     refreshBackoff();
 
-    auto dbStatus = ScopedShardDatabase::getOrCreate(txn, _nss.db());
-    if (!dbStatus.isOK()) {
-        return dbStatus.getStatus();
-    }
-
-    const auto& scopedDb = dbStatus.getValue();
+    ScopedChunkManager::refreshAndGet(txn, _nss);
 
-    // TODO: Improve synchronization and make more explicit
-    if (refreshType == RefreshType_RefreshChunkManager) {
-        try {
-            // Forces a remote check of the collection info, synchronization between threads happens
-            // internally
-            scopedDb.db()->getChunkManagerIfExists(txn, _nss.ns(), true);
-        } catch (const DBException& ex) {
-            return Status(ErrorCodes::UnknownError, ex.toString());
-        }
+    auto scopedCMStatus = ScopedChunkManager::get(txn, _nss);
+    if (!scopedCMStatus.isOK()) {
+        return scopedCMStatus.getStatus();
     }
 
-    scopedDb.db()->getChunkManagerOrPrimary(txn, _nss.ns(), _manager, _primary);
+    const auto& scopedCM = scopedCMStatus.getValue();
+
+    _manager = scopedCM.cm();
+    _primary = scopedCM.primary();
 
     return Status::OK();
 }
diff --git a/src/mongo/s/commands/cluster_write.cpp b/src/mongo/s/commands/cluster_write.cpp
index 217c37e273b..b3b68e3af04 100644
--- a/src/mongo/s/commands/cluster_write.cpp
+++ b/src/mongo/s/commands/cluster_write.cpp
@@ -37,15 +37,12 @@
 #include "mongo/db/lasterror.h"
 #include "mongo/db/write_concern_options.h"
 #include "mongo/s/balancer_configuration.h"
-#include "mongo/s/catalog/catalog_cache.h"
 #include "mongo/s/catalog/sharding_catalog_client.h"
 #include "mongo/s/catalog/type_collection.h"
 #include "mongo/s/chunk.h"
-#include "mongo/s/chunk_manager.h"
 #include "mongo/s/chunk_manager_targeter.h"
 #include "mongo/s/client/dbclient_multi_command.h"
 #include "mongo/s/client/shard_registry.h"
-#include "mongo/s/config.h"
 #include "mongo/s/config_server_client.h"
 #include "mongo/s/grid.h"
 #include "mongo/s/shard_util.h"
@@ -176,34 +173,30 @@ BSONObj findExtremeKeyForShard(OperationContext* txn,
  * Splits the chunks touched based from the targeter stats if needed.
  */
 void splitIfNeeded(OperationContext* txn, const NamespaceString& nss, const TargeterStats& stats) {
-    auto status = Grid::get(txn)->catalogCache()->getDatabase(txn, nss.db().toString());
-    if (!status.isOK()) {
-        warning() << "failed to get database config for " << nss
-                  << " while checking for auto-split: " << status.getStatus();
+    auto scopedCMStatus = ScopedChunkManager::get(txn, nss);
+    if (!scopedCMStatus.isOK()) {
+        warning() << "failed to get collection information for " << nss
+                  << " while checking for auto-split" << causedBy(scopedCMStatus.getStatus());
         return;
     }
 
-    auto config = status.getValue();
+    const auto& scopedCM = scopedCMStatus.getValue();
 
-    std::shared_ptr<ChunkManager> chunkManager;
-    std::shared_ptr<Shard> dummyShard;
-    config->getChunkManagerOrPrimary(txn, nss.ns(), chunkManager, dummyShard);
-
-    if (!chunkManager) {
+    if (!scopedCM.cm()) {
         return;
     }
 
     for (auto it = stats.chunkSizeDelta.cbegin(); it != stats.chunkSizeDelta.cend(); ++it) {
         std::shared_ptr<Chunk> chunk;
         try {
-            chunk = chunkManager->findIntersectingChunkWithSimpleCollation(txn, it->first);
+            chunk = scopedCM.cm()->findIntersectingChunkWithSimpleCollation(txn, it->first);
         } catch (const AssertionException& ex) {
             warning() << "could not find chunk while checking for auto-split: "
                       << causedBy(redact(ex));
             return;
         }
 
-        updateChunkWriteStatsAndSplitIfNeeded(txn, chunkManager.get(), chunk.get(), it->second);
+        updateChunkWriteStatsAndSplitIfNeeded(txn, scopedCM.cm().get(), chunk.get(), it->second);
     }
 }
 
diff --git a/src/mongo/s/config.cpp b/src/mongo/s/config.cpp
index 7ab8766877e..fea546c14a4 100644
--- a/src/mongo/s/config.cpp
+++ b/src/mongo/s/config.cpp
@@ -42,7 +42,6 @@
 #include "mongo/s/catalog/type_database.h"
 #include "mongo/s/chunk_manager.h"
 #include "mongo/s/chunk_version.h"
-#include "mongo/s/client/shard_registry.h"
 #include "mongo/s/grid.h"
 #include "mongo/stdx/memory.h"
 #include "mongo/util/log.h"
@@ -80,36 +79,6 @@ void DBConfig::markNSNotSharded(const std::string& ns) {
     }
 }
 
-void DBConfig::getChunkManagerOrPrimary(OperationContext* txn,
-                                        const std::string& ns,
-                                        std::shared_ptr<ChunkManager>& manager,
-                                        std::shared_ptr<Shard>& primary) {
-    manager.reset();
-    primary.reset();
-
-    const auto shardRegistry = Grid::get(txn)->shardRegistry();
-
-    stdx::lock_guard<stdx::mutex> lk(_lock);
-
-    auto it = _collections.find(ns);
-
-    if (it == _collections.end()) {
-        // If we don't know about this namespace, it's unsharded by default
-        auto shardStatus = shardRegistry->getShard(txn, _primaryId);
-        if (!shardStatus.isOK()) {
-            uasserted(40371,
-                      str::stream() << "The primary shard for collection " << ns
-                                    << " could not be loaded due to error "
-                                    << shardStatus.getStatus().toString());
-        }
-
-        primary = std::move(shardStatus.getValue());
-    } else {
-        const auto& ci = it->second;
-        manager = ci.cm;
-    }
-}
-
 std::shared_ptr<ChunkManager> DBConfig::getChunkManagerIfExists(OperationContext* txn,
                                                                 const std::string& ns,
                                                                 bool shouldReload,
diff --git a/src/mongo/s/config.h b/src/mongo/s/config.h
index 52b9afe9aa3..acc0c4968c3 100644
--- a/src/mongo/s/config.h
+++ b/src/mongo/s/config.h
@@ -33,7 +33,7 @@
 
 #include "mongo/db/repl/optime.h"
 #include "mongo/platform/atomic_word.h"
-#include "mongo/s/client/shard.h"
+#include "mongo/s/shard_id.h"
 #include "mongo/stdx/mutex.h"
 
 namespace mongo {
@@ -81,13 +81,6 @@ public:
      */
     bool isSharded(const std::string& ns);
 
-    // Atomically returns *either* the chunk manager *or* the primary shard for the collection,
-    // neither if the collection doesn't exist.
-    void getChunkManagerOrPrimary(OperationContext* txn,
-                                  const std::string& ns,
-                                  std::shared_ptr<ChunkManager>& manager,
-                                  std::shared_ptr<Shard>& primary);
-
     std::shared_ptr<ChunkManager> getChunkManager(OperationContext* txn,
                                                   const std::string& ns,
                                                   bool reload = false,
diff --git a/src/mongo/s/query/cluster_find.cpp b/src/mongo/s/query/cluster_find.cpp
index ab5b15b0f49..c1d32e5c6be 100644
--- a/src/mongo/s/query/cluster_find.cpp
+++ b/src/mongo/s/query/cluster_find.cpp
@@ -320,23 +320,19 @@ StatusWith<CursorId> ClusterFind::runQuery(OperationContext* txn,
     // Re-target and re-send the initial find command to the shards until we have established the
     // shard version.
     for (size_t retries = 1; retries <= kMaxStaleConfigRetries; ++retries) {
-        auto dbConfigStatus = ScopedShardDatabase::getExisting(txn, query.nss().db());
-        if (dbConfigStatus == ErrorCodes::NamespaceNotFound) {
+        auto scopedCMStatus = ScopedChunkManager::get(txn, query.nss());
+        if (scopedCMStatus == ErrorCodes::NamespaceNotFound) {
             // If the database doesn't exist, we successfully return an empty result set without
             // creating a cursor.
             return CursorId(0);
-        } else if (!dbConfigStatus.isOK()) {
-            return dbConfigStatus.getStatus();
+        } else if (!scopedCMStatus.isOK()) {
+            return scopedCMStatus.getStatus();
         }
 
-        const auto& dbConfig = dbConfigStatus.getValue();
-
-        std::shared_ptr<ChunkManager> chunkManager;
-        std::shared_ptr<Shard> primary;
-        dbConfig.db()->getChunkManagerOrPrimary(txn, query.nss().ns(), chunkManager, primary);
+        const auto& scopedCM = scopedCMStatus.getValue();
 
         auto cursorId = runQueryWithoutRetrying(
-            txn, query, readPref, chunkManager.get(), std::move(primary), results, viewDefinition);
+            txn, query, readPref, scopedCM.cm().get(), scopedCM.primary(), results, viewDefinition);
         if (cursorId.isOK()) {
             return cursorId;
         }
@@ -357,7 +353,7 @@ StatusWith<CursorId> ClusterFind::runQuery(OperationContext* txn,
         if (status == ErrorCodes::StaleEpoch) {
             Grid::get(txn)->catalogCache()->invalidate(query.nss().db().toString());
         } else {
-            dbConfig.db()->getChunkManagerIfExists(txn, query.nss().ns(), true);
+            scopedCM.db()->getChunkManagerIfExists(txn, query.nss().ns(), true);
         }
     }