Remove multiple declarations o kMicrosInSecond.

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/5526

Test Plan:
OPT=-g V=1 make J=1 unity_test -j32
make clean && make -j32

Differential Revision: D16079315

Pulled By: HaoyuHuang

fbshipit-source-id: 294ab439cf0db8dd5da44e30eabf0cbb2bb8c4f6

db/db_impl/db_impl.cc

@@ -101,7 +101,6 @@ namespace rocksdb {
 const std::string kDefaultColumnFamilyName("default");
 const std::string kPersistentStatsColumnFamilyName(
     "___rocksdb_stats_history___");
-const int kMicrosInSecond = 1000 * 1000;
 void DumpRocksDBBuildVersion(Logger* log);
 
 CompressionType GetCompressionFlush(

tools/block_cache_trace_analyzer_test.cc

@@ -91,7 +91,7 @@ class BlockCacheTracerTest : public testing::Test {
     assert(writer);
     for (uint32_t i = 0; i < nblocks; i++) {
       uint32_t key_id = from_key_id + i;
-      uint32_t timestamp = (key_id + 1) * kMicrosInSecond;
+      uint64_t timestamp = (key_id + 1) * kMicrosInSecond;
       BlockCacheTraceRecord record;
       record.block_type = block_type;
       record.block_size = kBlockSize + key_id;

tools/db_bench_tool.cc

@@ -1547,7 +1547,6 @@ class ReporterAgent {
  private:
   std::string Header() const { return "secs_elapsed,interval_qps"; }
   void SleepAndReport() {
-    uint64_t kMicrosInSecond = 1000 * 1000;
     auto time_started = env_->NowMicros();
     while (true) {
       {

trace_replay/block_cache_tracer.cc

@@ -28,6 +28,7 @@ bool ShouldTrace(const Slice& block_key, const TraceOptions& trace_options) {
 }
 }  // namespace
 
+const uint64_t kMicrosInSecond = 1000 * 1000;
 const std::string BlockCacheTraceHelper::kUnknownColumnFamilyName =
     "UnknownColumnFamily";
 

trace_replay/block_cache_tracer.h

@@ -16,6 +16,8 @@
 
 namespace rocksdb {
 
+extern const uint64_t kMicrosInSecond;
+
 // Lookup context for tracing block cache accesses.
 // We trace block accesses at five places:
 // 1. BlockBasedTable::GetFilter

utilities/simulator_cache/cache_simulator.h

@@ -10,8 +10,6 @@
 
 namespace rocksdb {
 
-const uint64_t kMicrosInSecond = 1000000;
-
 // A cache configuration provided by user.
 struct CacheConfiguration {
   std::string cache_name;  // LRU.