Separeate main from bench functionality to allow cusomizations

Summary: Isolate db_bench functionality from main so custom benchmark code can be written and managed

Test Plan:
Tested commands
./build_tools/regression_build_test.sh
./db_bench --db=/tmp/rocksdbtest-12321/dbbench --stats_interval_seconds=1 --num=1000
./db_bench --db=/tmp/rocksdbtest-12321/dbbench --stats_interval_seconds=1 --num=1000 --reads=500 --writes=500
./db_bench --db=/tmp/rocksdbtest-12321/dbbench --stats_interval_seconds=1 --num=1000 --merge_keys=100 --numdistinct=100 --num_column_families=3 --num_hot_column_families=1
./db_bench --stats_interval_seconds=1 --num=1000 --bloom_locality=1 --seed=5 --threads=5
./db_bench --duration=60 --value_size=50 --seek_nexts=10 --reverse_iterator=true --usee_uint64_comparator=true --batch-size=5
./db_bench --duration=60 --value_size=50 --seek_nexts=10 --reverse_iterator=true --use_uint64_comparator=true --batch_size=5
./db_bench --duration=60 --value_size=50 --seek_nexts=10 --reverse_iterator=true --usee_uint64_comparator=true --batch-size=5

Test Results - https://phabricator.fb.com/P56130387

Additional tests for:
./db_bench --duration=60 --value_size=50 --seek_nexts=10 --reverse_iterator=true --use_uint64_comparator=true --batch_size=5 --key_size=8 --merge_operator=put
./db_bench --stats_interval_seconds=1 --num=1000 --bloom_locality=1 --seed=5 --threads=5 --merge_operator=uint64add

Results: https://phabricator.fb.com/P56130607

Reviewers: yhchiang, sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D53991

Makefile

@@ -242,6 +242,8 @@ VALGRIND_VER := $(join $(VALGRIND_VER),valgrind)
 
 VALGRIND_OPTS = --error-exitcode=$(VALGRIND_ERROR) --leak-check=full
 
+BENCHTOOLOBJECTS = $(BENCH_SOURCES:.cc=.o) $(LIBOBJECTS) $(TESTUTIL)
+
 TESTS = \
 	db_test \
 	db_iter_test \
@@ -713,7 +715,7 @@ $(LIBRARY): $(LIBOBJECTS)
 	$(AM_V_AR)rm -f $@
 	$(AM_V_at)$(AR) $(ARFLAGS) $@ $(LIBOBJECTS)
 
-db_bench: db/db_bench.o $(LIBOBJECTS) $(TESTUTIL)
+db_bench: tools/db_bench.o $(BENCHTOOLOBJECTS)
 	$(AM_LINK)
 
 cache_bench: util/cache_bench.o $(LIBOBJECTS) $(TESTUTIL)

include/rocksdb/db_bench_tool.h

@@ -0,0 +1,9 @@
+// Copyright (c) 2013-present, Facebook, Inc.  All rights reserved.
+// This source code is licensed under the BSD-style license found in the
+// LICENSE file in the root directory of this source tree. An additional grant
+// of patent rights can be found in the PATENTS file in the same directory.
+#pragma once
+
+namespace rocksdb {
+int db_bench_tool(int argc, char** argv);
+}  // namespace rocksdb

src.mk

@@ -179,6 +179,9 @@ MOCK_SOURCES = \
   table/mock_table.cc \
   util/mock_env.cc
 
+BENCH_SOURCES = \
+  tools/db_bench_tool.cc
+
 TEST_BENCH_SOURCES =                                                    \
   third-party/gtest-1.7.0/fused-src/gtest/gtest-all.cc                  \
   db/auto_roll_logger_test.cc                                           \
@@ -189,7 +192,7 @@ TEST_BENCH_SOURCES =                                                    \
   db/comparator_db_test.cc                                              \
   db/corruption_test.cc                                                 \
   db/cuckoo_table_db_test.cc                                            \
-  db/db_bench.cc                                                        \
+  tools/db_bench_tool.cc                                                \
   db/dbformat_test.cc                                                   \
   db/db_iter_test.cc                                                    \
   db/db_test.cc                                                         \

tools/db_bench.cc

@@ -0,0 +1,23 @@
+//  Copyright (c) 2013-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under the BSD-style license found in the
+//  LICENSE file in the root directory of this source tree. An additional grant
+//  of patent rights can be found in the PATENTS file in the same directory.
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#ifndef __STDC_FORMAT_MACROS
+#define __STDC_FORMAT_MACROS
+#endif
+
+#ifndef GFLAGS
+#include <cstdio>
+int main() {
+  fprintf(stderr, "Please install gflags to run rocksdb tools\n");
+  return 1;
+}
+#else
+#include <rocksdb/db_bench_tool.h>
+int main(int argc, char** argv) { rocksdb::db_bench_tool(argc, argv); }
+#endif  // GFLAGS

tools/db_bench_tool.cc

@@ -11,14 +11,6 @@
 #define __STDC_FORMAT_MACROS
 #endif
 
-#ifndef GFLAGS
-#include <cstdio>
-int main() {
-  fprintf(stderr, "Please install gflags to run rocksdb tools\n");
-  return 1;
-}
-#else
-
 #ifdef NUMA
 #include <numa.h>
 #include <numaif.h>
@@ -76,6 +68,7 @@ int main() {
 #include <io.h>  // open/close
 #endif
 
+namespace {
 using GFLAGS::ParseCommandLineFlags;
 using GFLAGS::RegisterFlagValidator;
 using GFLAGS::SetUsageMessage;
@@ -521,7 +514,6 @@ DEFINE_uint64(transaction_lock_timeout, 100,
 DEFINE_bool(compaction_measure_io_stats, false,
             "Measure times spents on I/Os while in compactions. ");
 
-namespace {
 enum rocksdb::CompressionType StringToCompressionType(const char* ctype) {
   assert(ctype);
 
@@ -541,7 +533,7 @@ enum rocksdb::CompressionType StringToCompressionType(const char* ctype) {
     return rocksdb::kZSTDNotFinalCompression;
 
   fprintf(stdout, "Cannot parse compression type '%s'\n", ctype);
-  return rocksdb::kSnappyCompression; //default value
+  return rocksdb::kSnappyCompression;  // default value
 }
 
 std::string ColumnFamilyName(size_t i) {
@@ -553,7 +545,6 @@ std::string ColumnFamilyName(size_t i) {
     return std::string(name);
   }
 }
-}  // namespace
 
 DEFINE_string(compression_type, "snappy",
               "Algorithm to use to compress the database");
@@ -764,7 +755,6 @@ enum RepFactory {
   kCuckoo
 };
 
-namespace {
 enum RepFactory StringToRepFactory(const char* ctype) {
   assert(ctype);
 
@@ -782,7 +772,6 @@ enum RepFactory StringToRepFactory(const char* ctype) {
   fprintf(stdout, "Cannot parse memreptable %s\n", ctype);
   return kSkipList;
 }
-}  // namespace
 
 static enum RepFactory FLAGS_rep_factory;
 DEFINE_string(memtablerep, "skip_list", "");
@@ -834,6 +823,7 @@ static const bool FLAGS_deletepercent_dummy __attribute__((unused)) =
 static const bool FLAGS_table_cache_numshardbits_dummy __attribute__((unused)) =
     RegisterFlagValidator(&FLAGS_table_cache_numshardbits,
                           &ValidateTableCacheNumshardbits);
+}  // namespace
 
 namespace rocksdb {
 
@@ -2249,7 +2239,7 @@ class Benchmark {
       count++;
       thread->stats.FinishedOps(nullptr, nullptr, 1, kOthers);
     }
-    if (ptr == nullptr) exit(1); // Disable unused variable warning.
+    if (ptr == nullptr) exit(1);  // Disable unused variable warning.
   }
 
   void Compress(ThreadState *thread) {
@@ -4072,9 +4062,7 @@ class Benchmark {
   }
 };
 
-}  // namespace rocksdb
+int db_bench_tool(int argc, char** argv) {
-
-int main(int argc, char** argv) {
   rocksdb::port::InstallStackTraceHandler();
   SetUsageMessage(std::string("\nUSAGE:\n") + std::string(argv[0]) +
                   " [OPTIONS]...");
@@ -4143,5 +4131,4 @@ int main(int argc, char** argv) {
   benchmark.Run();
   return 0;
 }
-
+}  // namespace rocksdb
-#endif  // GFLAGS