Add TransactionDB::SingleDelete()

Summary:
Looks like the API is simply missing. Adding it.
Closes https://github.com/facebook/rocksdb/pull/2937

Differential Revision: D5919955

Pulled By: yiwu-arbug

fbshipit-source-id: 6e2e9c96c29882b0bb4113d1f8efb72bffc57878

include/rocksdb/utilities/transaction.h

@@ -344,6 +344,10 @@ class Transaction {
   virtual Status DeleteUntracked(ColumnFamilyHandle* column_family,
                                  const SliceParts& key) = 0;
   virtual Status DeleteUntracked(const SliceParts& key) = 0;
+  virtual Status SingleDeleteUntracked(ColumnFamilyHandle* column_family,
+                                       const Slice& key) = 0;
+
+  virtual Status SingleDeleteUntracked(const Slice& key) = 0;
 
   // Similar to WriteBatch::PutLogData
   virtual void PutLogData(const Slice& blob) = 0;

utilities/transactions/pessimistic_transaction_db.cc

@@ -396,6 +396,28 @@ Status PessimisticTransactionDB::Delete(const WriteOptions& wopts,
   return s;
 }
 
+Status PessimisticTransactionDB::SingleDelete(const WriteOptions& wopts,
+                                              ColumnFamilyHandle* column_family,
+                                              const Slice& key) {
+  Status s;
+
+  Transaction* txn = BeginInternalTransaction(wopts);
+  txn->DisableIndexing();
+
+  // Since the client didn't create a transaction, they don't care about
+  // conflict checking for this write.  So we just need to do
+  // SingleDeleteUntracked().
+  s = txn->SingleDeleteUntracked(column_family, key);
+
+  if (s.ok()) {
+    s = txn->Commit();
+  }
+
+  delete txn;
+
+  return s;
+}
+
 Status PessimisticTransactionDB::Merge(const WriteOptions& options,
                                        ColumnFamilyHandle* column_family,
                                        const Slice& key, const Slice& value) {

utilities/transactions/pessimistic_transaction_db.h

@@ -50,6 +50,11 @@ class PessimisticTransactionDB : public TransactionDB {
                         ColumnFamilyHandle* column_family,
                         const Slice& key) override;
 
+  using StackableDB::SingleDelete;
+  virtual Status SingleDelete(const WriteOptions& wopts,
+                              ColumnFamilyHandle* column_family,
+                              const Slice& key) override;
+
   using StackableDB::Merge;
   virtual Status Merge(const WriteOptions& options,
                        ColumnFamilyHandle* column_family, const Slice& key,

utilities/transactions/transaction_base.cc

@@ -471,6 +471,21 @@ Status TransactionBaseImpl::DeleteUntracked(ColumnFamilyHandle* column_family,
   return s;
 }
 
+Status TransactionBaseImpl::SingleDeleteUntracked(
+    ColumnFamilyHandle* column_family, const Slice& key) {
+  Status s = TryLock(column_family, key, false /* read_only */,
+                     true /* exclusive */, true /* untracked */);
+
+  if (s.ok()) {
+    s = GetBatchForWrite()->SingleDelete(column_family, key);
+    if (s.ok()) {
+      num_deletes_++;
+    }
+  }
+
+  return s;
+}
+
 void TransactionBaseImpl::PutLogData(const Slice& blob) {
   write_batch_.PutLogData(blob);
 }

utilities/transactions/transaction_base.h

@@ -170,6 +170,12 @@ class TransactionBaseImpl : public Transaction {
     return DeleteUntracked(nullptr, key);
   }
 
+  Status SingleDeleteUntracked(ColumnFamilyHandle* column_family,
+                               const Slice& key) override;
+  Status SingleDeleteUntracked(const Slice& key) override {
+    return SingleDeleteUntracked(nullptr, key);
+  }
+
   void PutLogData(const Slice& blob) override;
 
   WriteBatchWithIndex* GetWriteBatch() override;