feat: Support o_direct flag for read file (facebookincubator#12138)

Summary: Pull Request resolved: facebookincubator#12138

Reviewed By: yuandagits

Differential Revision: D68468301

velox/common/caching/SsdFile.cpp

@@ -118,9 +118,9 @@ SsdFile::SsdFile(const Config& config)
   process::TraceContext trace("SsdFile::SsdFile");
   filesystems::FileOptions fileOptions;
   fileOptions.shouldThrowOnFileAlreadyExists = false;
-  fileOptions.bufferWrite = !FLAGS_ssd_odirect;
+  fileOptions.bufferIo = !FLAGS_ssd_odirect;
   writeFile_ = fs_->openFileForWrite(fileName_, fileOptions);
-  readFile_ = fs_->openFileForRead(fileName_);
+  readFile_ = fs_->openFileForRead(fileName_, fileOptions);
 
   const uint64_t size = writeFile_->size();
   numRegions_ = std::min<int32_t>(size / kRegionSize, maxRegions_);

velox/common/file/File.cpp

@@ -129,8 +129,15 @@ uint64_t InMemoryWriteFile::size() const {
   return file_->size();
 }
 
-LocalReadFile::LocalReadFile(std::string_view path) : path_(path) {
-  fd_ = open(path_.c_str(), O_RDONLY);
+LocalReadFile::LocalReadFile(std::string_view path, bool bufferIo)
+    : path_(path) {
+  int32_t flags = O_RDONLY;
+#ifdef linux
+  if (!bufferIo) {
+    flags |= O_DIRECT;
+  }
+#endif // linux
+  fd_ = open(path_.c_str(), flags);
   if (fd_ < 0) {
     if (errno == ENOENT) {
       VELOX_FILE_NOT_FOUND_ERROR("No such file or directory: {}", path);
@@ -259,7 +266,7 @@ LocalWriteFile::LocalWriteFile(
     std::string_view path,
     bool shouldCreateParentDirectories,
     bool shouldThrowOnFileAlreadyExists,
-    bool bufferWrite)
+    bool bufferIo)
     : path_(path) {
   const auto dir = fs::path(path_).parent_path();
   if (shouldCreateParentDirectories && !fs::exists(dir)) {
@@ -274,7 +281,7 @@ LocalWriteFile::LocalWriteFile(
     flags |= O_EXCL;
   }
 #ifdef linux
-  if (!bufferWrite) {
+  if (!bufferIo) {
     flags |= O_DIRECT;
   }
 #endif // linux

velox/common/file/File.h

@@ -266,7 +266,7 @@ class InMemoryWriteFile final : public WriteFile {
 /// files match against any filepath starting with '/'.
 class LocalReadFile final : public ReadFile {
  public:
-  explicit LocalReadFile(std::string_view path);
+  explicit LocalReadFile(std::string_view path, bool bufferIo = true);
 
   /// TODO: deprecate this after creating local file all through velox fs
   /// interface.
@@ -327,7 +327,7 @@ class LocalWriteFile final : public WriteFile {
       std::string_view path,
       bool shouldCreateParentDirectories = false,
       bool shouldThrowOnFileAlreadyExists = true,
-      bool bufferWrite = true);
+      bool bufferIo = true);
 
   ~LocalWriteFile();
 

velox/common/file/FileSystems.cpp

@@ -97,8 +97,8 @@ class LocalFileSystem : public FileSystem {
 
   std::unique_ptr<ReadFile> openFileForRead(
       std::string_view path,
-      const FileOptions& /*unused*/) override {
-    return std::make_unique<LocalReadFile>(extractPath(path));
+      const FileOptions& options) override {
+    return std::make_unique<LocalReadFile>(extractPath(path), options.bufferIo);
   }
 
   std::unique_ptr<WriteFile> openFileForWrite(
@@ -108,7 +108,7 @@ class LocalFileSystem : public FileSystem {
         extractPath(path),
         options.shouldCreateParentDirectories,
         options.shouldThrowOnFileAlreadyExists,
-        options.bufferWrite);
+        options.bufferIo);
   }
 
   void remove(std::string_view path) override {

velox/common/file/FileSystems.h

@@ -58,12 +58,10 @@ struct FileOptions {
   /// NOTE: this only applies for write open file.
   bool shouldThrowOnFileAlreadyExists{true};
 
-  /// Whether to buffer the write data in file system client or not. For local
+  /// Whether to buffer the data in file system client or not. For local
   /// filesystem on Unix-like operating system, this corresponds to the direct
   /// IO mode if set.
-  ///
-  /// NOTE: this only applies for write open file.
-  bool bufferWrite{true};
+  bool bufferIo{true};
 };
 
 /// Defines directory options