Log GetCurrentTime failures during Flush and Compaction

Summary:
`GetCurrentTime()` is used to populate `creation_time` table property during flushes and compactions. It is safe to ignore `GetCurrentTime()` failures here but they should be logged.

(Note that `creation_time` property was introduced as part of TTL-based FIFO compaction in #2480.)

Tes Plan:
`make check`
Closes https://github.com/facebook/rocksdb/pull/3231

Differential Revision: D6501935

Pulled By: sagar0

fbshipit-source-id: 376adcf4ab801d3a43ec4453894b9a10909c8eb6

db/compaction_job.cc

@@ -1325,7 +1325,15 @@ Status CompactionJob::OpenCompactionOutputFile(
       sub_compact->compaction->MaxInputFileCreationTime();
   if (output_file_creation_time == 0) {
     int64_t _current_time = 0;
-    db_options_.env->GetCurrentTime(&_current_time);  // ignore error
+    auto status = db_options_.env->GetCurrentTime(&_current_time);
+    // Safe to proceed even if GetCurrentTime fails. So, log and proceed.
+    if (!status.ok()) {
+      ROCKS_LOG_WARN(
+          db_options_.info_log,
+          "Failed to get current time to populate creation_time property. "
+          "Status: %s",
+          status.ToString().c_str());
+    }
     output_file_creation_time = static_cast<uint64_t>(_current_time);
   }
 

db/flush_job.cc

@@ -299,7 +299,15 @@ Status FlushJob::WriteLevel0Table() {
       TEST_SYNC_POINT_CALLBACK("FlushJob::WriteLevel0Table:output_compression",
                                &output_compression_);
       int64_t _current_time = 0;
-      db_options_.env->GetCurrentTime(&_current_time);  // ignore error
+      auto status = db_options_.env->GetCurrentTime(&_current_time);
+      // Safe to proceed even if GetCurrentTime fails. So, log and proceed.
+      if (!status.ok()) {
+        ROCKS_LOG_WARN(
+            db_options_.info_log,
+            "Failed to get current time to populate creation_time property. "
+            "Status: %s",
+            status.ToString().c_str());
+      }
       const uint64_t current_time = static_cast<uint64_t>(_current_time);
 
       uint64_t oldest_key_time =