Revert "SERVER-21366 Periodically yield when applying migration deletions"

This reverts commit 934c5a5241edd01df270065831646d78ed5a80c1.

3 files changed, 14 insertions, 71 deletions

diff --git a/src/mongo/db/client.cpp b/src/mongo/db/client.cpp
index 142dd1f40bb..b357c317c33 100644
--- a/src/mongo/db/client.cpp
+++ b/src/mongo/db/client.cpp
@@ -200,13 +200,6 @@ Client::Context::Context(OperationContext* txn, const string& ns, bool doVersion
 AutoGetDb::AutoGetDb(OperationContext* txn, const StringData& ns, LockMode mode)
     : _dbLock(txn->lockState(), ns, mode), _db(dbHolder().get(txn, ns)) {}
 
-AutoGetCollection::AutoGetCollection(OperationContext* txn,
-                                     const NamespaceString& nss,
-                                     LockMode mode)
-    : _autoDb(txn, nss.db(), mode),
-      _collLock(txn->lockState(), nss.ns(), mode),
-      _coll(_autoDb.getDb() ? _autoDb.getDb()->getCollection(nss) : nullptr) {}
-
 AutoGetOrCreateDb::AutoGetOrCreateDb(OperationContext* txn, const StringData& ns, LockMode mode)
     : _transaction(txn, MODE_IX),
       _dbLock(txn->lockState(), ns, mode),
diff --git a/src/mongo/db/client.h b/src/mongo/db/client.h
index 0ddbd2df084..61e82acc01f 100644
--- a/src/mongo/db/client.h
+++ b/src/mongo/db/client.h
@@ -89,33 +89,6 @@ private:
 };
 
 /**
- * RAII-style class, which acquires a locks on the specified database and collection in the
- * requested mode and obtains references to both.
- *
- * It is guaranteed that locks will be released when this object goes out of scope, therefore
- * the database and the collection references returned by this class should not be retained.
- */
-class AutoGetCollection {
-    MONGO_DISALLOW_COPYING(AutoGetCollection);
-
-public:
-    AutoGetCollection(OperationContext* txn, const NamespaceString& nss, LockMode mode);
-
-    Database* getDb() const {
-        return _autoDb.getDb();
-    }
-
-    Collection* getCollection() const {
-        return _coll;
-    }
-
-private:
-    const AutoGetDb _autoDb;
-    const Lock::CollectionLock _collLock;
-    Collection* const _coll;
-};
-
-/**
  * RAII-style class, which acquires a lock on the specified database in the requested mode and
  * obtains a reference to the database, creating it was non-existing. Used as a shortcut for
  * calls to dbHolder().openDb(), taking care of locking details. The requested mode must be
diff --git a/src/mongo/s/d_migrate.cpp b/src/mongo/s/d_migrate.cpp
index 080a877454d..77beca54897 100644
--- a/src/mongo/s/d_migrate.cpp
+++ b/src/mongo/s/d_migrate.cpp
@@ -1897,7 +1897,7 @@ public:
                 _errmsg = "UNKNOWN ERROR";
             }
 
-            severe() << "migrate failed with unknown exception" << migrateLog;
+            error() << "migrate failed with unknown exception" << migrateLog;
         }
 
         if (getState() != DONE) {
@@ -2385,54 +2385,33 @@ public:
         bool didAnything = false;
 
         if (xfer["deleted"].isABSONObj()) {
-            scoped_ptr<Helpers::RemoveSaver> removeSaver;
-            if (serverGlobalParams.moveParanoia) {
-                removeSaver.reset(new Helpers::RemoveSaver("moveChunk", ns, "removedDuring"));
-            }
-
-            scoped_ptr<ScopedTransaction> autoXact;
-            scoped_ptr<AutoGetCollection> autoColl;
-
-            const int maxItersBeforeYield =
-                std::max(static_cast<int>(internalQueryExecYieldIterations), 1);
-            int opCounter = 0;
+            ScopedTransaction transaction(txn, MODE_IX);
+            Lock::DBLock dlk(txn->lockState(), nsToDatabaseSubstring(ns), MODE_IX);
+            Helpers::RemoveSaver rs("moveChunk", ns, "removedDuring");
 
             BSONObjIterator i(xfer["deleted"].Obj());
             while (i.more()) {
-                if (opCounter % maxItersBeforeYield == 0) {
-                    autoXact.reset();
-                    autoColl.reset();
-                    autoXact.reset(new ScopedTransaction(txn, MODE_IX));
-                    autoColl.reset(new AutoGetCollection(txn, NamespaceString(ns), MODE_X));
-                }
-
-                // If the collection does not exist there won't be any documents to remove. This
-                // condition can only happen if deletions are happening for an empty chunk or in the
-                // unlikely event that someone manually deleted the collection.
-                if (!autoColl->getCollection()) {
-                    break;
-                }
+                Lock::CollectionLock clk(txn->lockState(), ns, MODE_X);
+                Client::Context ctx(txn, ns);
 
                 BSONObj id = i.next().Obj();
 
-                // Increment the counter before doing either the read or delete, so we yield the WT
-                // snapshot more aggressively
-                opCounter++;
-
                 // do not apply deletes if they do not belong to the chunk being migrated
                 BSONObj fullObj;
-                if (Helpers::findById(txn, autoColl->getDb(), ns.c_str(), id, fullObj)) {
+                if (Helpers::findById(txn, ctx.db(), ns.c_str(), id, fullObj)) {
                     if (!isInRange(fullObj, min, max, shardKeyPattern)) {
+                        log() << "not applying out of range deletion: " << fullObj << migrateLog;
+
                         continue;
                     }
                 }
 
-                if (removeSaver) {
-                    removeSaver->goingToDelete(fullObj);
+                if (serverGlobalParams.moveParanoia) {
+                    rs.goingToDelete(fullObj);
                 }
 
                 deleteObjects(txn,
-                              autoColl->getDb(),
+                              ctx.db(),
                               ns,
                               id,
                               PlanExecutor::YIELD_MANUAL,
@@ -2441,7 +2420,7 @@ public:
                               false /* god */,
                               true /* fromMigrate */);
 
-                *lastOpApplied = txn->getClient()->getLastOp().asDate();
+                *lastOpApplied = ctx.getClient()->getLastOp().asDate();
                 didAnything = true;
             }
         }
@@ -2657,9 +2636,7 @@ void migrateThread(std::string ns,
                    std::string fromShard,
                    OID epoch,
                    WriteConcernOptions writeConcern) {
-    const std::string migrateThreadName(str::stream() << "migrateThread-" << ns);
-    Client::initThread(migrateThreadName.c_str());
-
+    Client::initThread("migrateThread");
     OperationContextImpl txn;
     if (getGlobalAuthorizationManager()->isAuthEnabled()) {
         ShardedConnectionInfo::addHook();