message: Add VLOG statements for each main function call
diff: @@ -185,6 +185,7 @@ class S3RandomAccessFile : public RandomAccessFile {
  Status Read(uint64 offset, size_t n, StringPiece* result,
  char* scratch) const override {
  + VLOG(1) << "ReadFilefromS3 s3://" << bucket_ << "/" << object_ << " from " << offset << " for n:" << n;
  Aws::S3::Model::GetObjectRequest getObjectRequest;
  getObjectRequest.WithBucket(bucket_.c_str()).WithKey(object_.c_str());
  string bytes = strings::StrCat("bytes=", offset, "-", offset + n - 1);
  @@ -260,6 +261,7 @@ class S3WritableFile : public WritableFile {
  if (!sync_needed_) {
  return Status::OK();
  }
  + VLOG(1) << "WriteFileToS3: s3://" << bucket_ << "/" << object_;
  Aws::S3::Model::PutObjectRequest putObjectRequest;
  putObjectRequest.WithBucket(bucket_.c_str()).WithKey(object_.c_str());
  long offset = outfile_->tellp();
  @@ -405,6 +407,7 @@ Status S3FileSystem::FileExists(const string& fname) {
  Status S3FileSystem::GetChildren(const string& dir,
  std::vector<string>* result) {
  + VLOG(1) << "GetChildren for path: " << dir;
  string bucket, prefix;
  TF_RETURN_IF_ERROR(ParseS3Path(dir, true, &bucket, &prefix));
  @@ -452,6 +455,7 @@ Status S3FileSystem::GetChildren(const string& dir,
  }
  Status S3FileSystem::Stat(const string& fname, FileStatistics* stats) {
  + VLOG(1) << "Stat on path: " << fname;
  string bucket, object;
  TF_RETURN_IF_ERROR(ParseS3Path(fname, true, &bucket, &object));
  @@ -513,6 +517,7 @@ Status S3FileSystem::GetMatchingPaths(const string& pattern,
  }
  Status S3FileSystem::DeleteFile(const string& fname) {
  + VLOG(1) << "DeleteFile: " << fname;
  string bucket, object;
  TF_RETURN_IF_ERROR(ParseS3Path(fname, false, &bucket, &object));
  @@ -529,6 +534,7 @@ Status S3FileSystem::DeleteFile(const string& fname) {
  }
  Status S3FileSystem::CreateDir(const string& dirname) {
  + VLOG(1) << "CreateDir: " << dirname;
  string bucket, object;
  TF_RETURN_IF_ERROR(ParseS3Path(dirname, true, &bucket, &object));
  @@ -552,6 +558,7 @@ Status S3FileSystem::CreateDir(const string& dirname) {
  }
  Status S3FileSystem::DeleteDir(const string& dirname) {
  + VLOG(1) << "DeleteDir: " << dirname;
  string bucket, object;
  TF_RETURN_IF_ERROR(ParseS3Path(dirname, false, &bucket, &object));
  @@ -592,6 +599,7 @@ Status S3FileSystem::GetFileSize(const string& fname, uint64* file_size) {
  }
  Status S3FileSystem::RenameFile(const string& src, const string& target) {
  + VLOG(1) << "RenameFile from: " << src << " to: " << target;
  string src_bucket, src_object, target_bucket, target_object;
  TF_RETURN_IF_ERROR(ParseS3Path(src, false, &src_bucket, &src_object));
  TF_RETURN_IF_ERROR(
  