Add AppendWithVerify and PositionedAppendWithVerify to Env and FileSy…

…stem (#7419)

Summary:
Add new AppendWithVerify and PositionedAppendWithVerify APIs to Env and FileSystem to bring the data verification information (data checksum information) from upper layer (e.g., WritableFileWriter) to the storage layer. This PR only include the API definition, no functional codes are added to unblock other developers which depend on these APIs.

Pull Request resolved: facebook/rocksdb#7419

Test Plan: make -j32

Reviewed By: pdillinger

Differential Revision: D23883196

Pulled By: zhichao-cao

fbshipit-source-id: 94676c26bc56144cc32e3661f84f21eccd790411
Signed-off-by: Changlong Chen <levisonchen@live.cn>

include/rocksdb/file_system.h

@@ -702,6 +702,13 @@ class FSRandomAccessFile {
   // RandomAccessFileWrapper too.
 };
 
+// A data structure brings the data verification information, which is
+// used togther with data being written to a file.
+struct DataVerificationInfo {
+  // checksum of the data being written.
+  Slice checksum;
+};
+
 // A file abstraction for sequential writing.  The implementation
 // must provide buffering since callers may append small fragments
 // at a time to the file.
@@ -729,6 +736,16 @@ class FSWritableFile {
   virtual IOStatus Append(const Slice& data, const IOOptions& options,
                           IODebugContext* dbg) = 0;
 
+  // EXPERIMENTAL / CURRENTLY UNUSED
+  // Append data with verification information
+  // Note that this API change is experimental and it might be changed in
+  // the future. Currently, RocksDB does not use this API.
+  virtual IOStatus Append(const Slice& data, const IOOptions& options,
+                          const DataVerificationInfo& /* verification_info */,
+                          IODebugContext* dbg) {
+    return Append(data, options, dbg);
+  }
+
   // PositionedAppend data to the specified offset. The new EOF after append
   // must be larger than the previous EOF. This is to be used when writes are
   // not backed by OS buffers and hence has to always start from the start of
@@ -756,6 +773,18 @@ class FSWritableFile {
     return IOStatus::NotSupported();
   }
 
+  // EXPERIMENTAL / CURRENTLY UNUSED
+  // PositionedAppend data with verification information.
+  // Note that this API change is experimental and it might be changed in
+  // the future. Currently, RocksDB does not use this API.
+  virtual IOStatus PositionedAppend(
+      const Slice& /* data */, uint64_t /* offset */,
+      const IOOptions& /*options*/,
+      const DataVerificationInfo& /* verification_info */,
+      IODebugContext* /*dbg*/) {
+    return IOStatus::NotSupported();
+  }
+
   // Truncate is necessary to trim the file to the correct size
   // before closing. It is not always possible to keep track of the file
   // size due to whole pages writes. The behavior is undefined if called
@@ -1286,11 +1315,23 @@ class FSWritableFileWrapper : public FSWritableFile {
                   IODebugContext* dbg) override {
     return target_->Append(data, options, dbg);
   }
+  IOStatus Append(const Slice& data, const IOOptions& options,
+                  const DataVerificationInfo& verification_info,
+                  IODebugContext* dbg) override {
+    return target_->Append(data, options, verification_info, dbg);
+  }
   IOStatus PositionedAppend(const Slice& data, uint64_t offset,
                             const IOOptions& options,
                             IODebugContext* dbg) override {
     return target_->PositionedAppend(data, offset, options, dbg);
   }
+  IOStatus PositionedAppend(const Slice& data, uint64_t offset,
+                            const IOOptions& options,
+                            const DataVerificationInfo& verification_info,
+                            IODebugContext* dbg) override {
+    return target_->PositionedAppend(data, offset, options, verification_info,
+                                     dbg);
+  }
   IOStatus Truncate(uint64_t size, const IOOptions& options,
                     IODebugContext* dbg) override {
     return target_->Truncate(size, options, dbg);