IOStatsContext::ToString() add option to exclude zero counters

Summary: similar to D52809 add option to exclude zero counters.

Test Plan:
[yiwu@dev4504.prn1 ~/rocksdb] ./iostats_context_test
[==========] Running 1 test from 1 test case.
[----------] Global test environment set-up.
[----------] 1 test from IOStatsContextTest
[ RUN      ] IOStatsContextTest.ToString
[       OK ] IOStatsContextTest.ToString (0 ms)
[----------] 1 test from IOStatsContextTest (0 ms total)

[----------] Global test environment tear-down
[==========] 1 test from 1 test case ran. (0 ms total)
[  PASSED  ] 1 test.

Reviewers: anthony, yhchiang, andrewkr, IslamAbdelRahman, kradhakrishnan, sdong

Reviewed By: sdong

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D54591

CMakeLists.txt

@@ -391,6 +391,7 @@ set(TESTS
         util/file_reader_writer_test.cc
         util/heap_test.cc
         util/histogram_test.cc
+        util/iostats_context_test.cc
         util/memenv_test.cc
         util/mock_env_test.cc
         util/options_test.cc

Makefile

@@ -340,7 +340,8 @@ TESTS = \
 	compact_on_deletion_collector_test \
 	compaction_job_stats_test \
 	transaction_test \
-	ldb_cmd_test
+	ldb_cmd_test \
+	iostats_context_test
 
 SUBSET :=  $(shell echo $(TESTS) |sed s/^.*$(ROCKSDBTESTS_START)/$(ROCKSDBTESTS_START)/)
 
@@ -1045,6 +1046,9 @@ ldb_cmd_test: tools/ldb_cmd_test.o $(LIBOBJECTS) $(TESTHARNESS)
 ldb: tools/ldb.o $(LIBOBJECTS)
 	$(AM_LINK)
 
+iostats_context_test: util/iostats_context_test.o $(LIBOBJECTS) $(TESTHARNESS)
+	$(AM_V_CCLD)$(CXX) $^ $(EXEC_LDFLAGS) -o $@ $(LDFLAGS)
+
 #-------------------------------------------------
 # make install related stuff
 INSTALL_PATH ?= /usr/local

include/rocksdb/iostats_context.h

@@ -18,7 +18,7 @@ struct IOStatsContext {
   // reset all io-stats counter to zero
   void Reset();
 
-  std::string ToString() const;
+  std::string ToString(bool exclude_zero_counters = false) const;
 
   // the thread pool id
   uint64_t thread_pool_id;

src.mk

@@ -269,6 +269,7 @@ TEST_BENCH_SOURCES =                                                    \
   utilities/transactions/transaction_test.cc                            \
   utilities/ttl/ttl_test.cc                                             \
   utilities/write_batch_with_index/write_batch_with_index_test.cc       \
+	util/iostats_context_test.cc																					\
   util/log_write_bench.cc                                               \
   util/memenv_test.cc                                                   \
   util/mock_env_test.cc                                                 \

util/iostats_context.cc

@@ -31,21 +31,24 @@ void IOStatsContext::Reset() {
   logger_nanos = 0;
 }
 
-#define IOSTATS_CONTEXT_OUTPUT(counter) #counter << " = " << counter << ", "
+#define IOSTATS_CONTEXT_OUTPUT(counter)         \
+  if (!exclude_zero_counters || counter > 0) {  \
+    ss << #counter << " = " << counter << ", "; \
+  }
 
-std::string IOStatsContext::ToString() const {
+std::string IOStatsContext::ToString(bool exclude_zero_counters) const {
   std::ostringstream ss;
-  ss << IOSTATS_CONTEXT_OUTPUT(thread_pool_id)
-     << IOSTATS_CONTEXT_OUTPUT(bytes_read)
-     << IOSTATS_CONTEXT_OUTPUT(bytes_written)
-     << IOSTATS_CONTEXT_OUTPUT(open_nanos)
-     << IOSTATS_CONTEXT_OUTPUT(allocate_nanos)
-     << IOSTATS_CONTEXT_OUTPUT(write_nanos)
-     << IOSTATS_CONTEXT_OUTPUT(read_nanos)
-     << IOSTATS_CONTEXT_OUTPUT(range_sync_nanos)
-     << IOSTATS_CONTEXT_OUTPUT(fsync_nanos)
-     << IOSTATS_CONTEXT_OUTPUT(prepare_write_nanos)
-     << IOSTATS_CONTEXT_OUTPUT(logger_nanos);
+  IOSTATS_CONTEXT_OUTPUT(thread_pool_id);
+  IOSTATS_CONTEXT_OUTPUT(bytes_read);
+  IOSTATS_CONTEXT_OUTPUT(bytes_written);
+  IOSTATS_CONTEXT_OUTPUT(open_nanos);
+  IOSTATS_CONTEXT_OUTPUT(allocate_nanos);
+  IOSTATS_CONTEXT_OUTPUT(write_nanos);
+  IOSTATS_CONTEXT_OUTPUT(read_nanos);
+  IOSTATS_CONTEXT_OUTPUT(range_sync_nanos);
+  IOSTATS_CONTEXT_OUTPUT(fsync_nanos);
+  IOSTATS_CONTEXT_OUTPUT(prepare_write_nanos);
+  IOSTATS_CONTEXT_OUTPUT(logger_nanos);
 
   return ss.str();
 }

util/iostats_context_test.cc

@@ -0,0 +1,29 @@
+// Copyright (c) 2011-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.
+
+#include "rocksdb/iostats_context.h"
+#include "util/testharness.h"
+
+namespace rocksdb {
+
+TEST(IOStatsContextTest, ToString) {
+  iostats_context.Reset();
+  iostats_context.bytes_read = 12345;
+
+  std::string zero_included = iostats_context.ToString();
+  ASSERT_NE(std::string::npos, zero_included.find("= 0"));
+  ASSERT_NE(std::string::npos, zero_included.find("= 12345"));
+
+  std::string zero_excluded = iostats_context.ToString(true);
+  ASSERT_EQ(std::string::npos, zero_excluded.find("= 0"));
+  ASSERT_NE(std::string::npos, zero_excluded.find("= 12345"));
+}
+
+}  // namespace rocksdb
+
+int main(int argc, char** argv) {
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}