Dedup IsFileSectorAligned() to fix unity build. (#5812)

Summary:
Unity build fails because of name conflict of IsFileSectorAligned() after recent refactoring. Consolidate the function.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5812

Test Plan: make unity. At least the failure goes away. Also "make all", "make release" and see no regression in normal cases.

Differential Revision: D17411403

fbshipit-source-id: 09d5653471ae2c3a4d898e120a024f7dd08d9c9d

file/read_write_util.cc

@@ -58,4 +58,9 @@ bool ReadOneLine(std::istringstream* iss, SequentialFile* seq_file,
   return *has_data || has_complete_line;
 }
 
+#ifndef NDEBUG
+bool IsFileSectorAligned(const size_t off, size_t sector_size) {
+  return off % sector_size == 0;
+}
+#endif  // NDEBUG
 }  // namespace rocksdb

file/read_write_util.h

@@ -26,4 +26,7 @@ extern Status NewWritableFile(Env* env, const std::string& fname,
 bool ReadOneLine(std::istringstream* iss, SequentialFile* seq_file,
                  std::string* output, bool* has_data, Status* result);
 
+#ifndef NDEBUG
+bool IsFileSectorAligned(const size_t off, size_t sector_size);
+#endif  // NDEBUG
 }  // namespace rocksdb

file/readahead_raf.cc

@@ -11,19 +11,11 @@
 
 #include <algorithm>
 #include <mutex>
+#include "file/read_write_util.h"
 #include "util/aligned_buffer.h"
 #include "util/rate_limiter.h"
 
 namespace rocksdb {
-
-#ifndef NDEBUG
-namespace {
-bool IsFileSectorAligned(const size_t off, size_t sector_size) {
-  return off % sector_size == 0;
-}
-}  // namespace
-#endif
-
 namespace {
 class ReadaheadRandomAccessFile : public RandomAccessFile {
  public:

file/sequence_file_reader.cc

@@ -12,6 +12,7 @@
 #include <algorithm>
 #include <mutex>
 
+#include "file/read_write_util.h"
 #include "monitoring/histogram.h"
 #include "monitoring/iostats_context_imp.h"
 #include "port/port.h"
@@ -21,15 +22,6 @@
 #include "util/rate_limiter.h"
 
 namespace rocksdb {
-
-#ifndef NDEBUG
-namespace {
-bool IsFileSectorAligned(const size_t off, size_t sector_size) {
-  return off % sector_size == 0;
-}
-}  // namespace
-#endif
-
 Status SequentialFileReader::Read(size_t n, Slice* result, char* scratch) {
   Status s;
   if (use_direct_io()) {