remove tailing_iter.h/cc

Summary: as title

Test Plan:
make all check
ran db_bench and saw seek stats at the end

Reviewers: yhchiang, igor, sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D21651

Author: Lei Jin

Makefile

@@ -116,7 +116,8 @@ TESTS = \
 	table_test \
 	thread_local_test \
 	geodb_test \
- 	rate_limiter_test \
+	rate_limiter_test \
+	cuckoo_table_builder_test \
 	options_test \
 	cuckoo_table_builder_test \
 	cuckoo_table_reader_test \
@@ -235,7 +236,7 @@ valgrind_check: all $(PROGRAMS) $(TESTS)
 		echo $$t $$((etime - stime)) >> $(VALGRIND_DIR)/valgrind_tests_times; \
 	done
 
-unity.cc:	
+unity.cc:
 	$(shell (export ROCKSDB_ROOT="$(CURDIR)"; "$(CURDIR)/build_tools/unity" "$(CURDIR)/unity.cc"))
 
 unity: unity.cc unity.o

db/db_impl.cc

@@ -35,7 +35,6 @@
 #include "db/merge_helper.h"
 #include "db/table_cache.h"
 #include "db/table_properties_collector.h"
-#include "db/tailing_iter.h"
 #include "db/forward_iterator.h"
 #include "db/transaction_log_impl.h"
 #include "db/version_set.h"
@@ -3704,7 +3703,10 @@ Status DBImpl::NewIterators(
 #else
     for (auto cfh : column_families) {
       auto cfd = reinterpret_cast<ColumnFamilyHandleImpl*>(cfh)->cfd();
-      iterators->push_back(new TailingIterator(env_, this, options, cfd));
+      auto iter = new ForwardIterator(this, options, cfd);
+      iterators->push_back(
+          NewDBIterator(env_, *cfd->options(), cfd->user_comparator(), iter,
+                        kMaxSequenceNumber));
     }
 #endif
   } else {