niyue commented on a change in pull request #11486:
URL: https://github.com/apache/arrow/pull/11486#discussion_r740216701
##########
File path: cpp/src/arrow/ipc/reader.cc
##########
@@ -1358,6 +1398,62 @@ Future<std::shared_ptr<RecordBatchFileReader>>
RecordBatchFileReader::OpenAsync(
.Then([=]() -> Result<std::shared_ptr<RecordBatchFileReader>> { return
result; });
}
+Result<int64_t> IoRecordedRandomAccessFile::GetSize() { return file_size_; }
+
+Result<int64_t> IoRecordedRandomAccessFile::ReadAt(int64_t position, int64_t
nbytes,
+ void* out) {
+ auto num_bytes_read = std::min(file_size_, position + nbytes) - position;
+
+ if (!recorded_reads_.empty() &&
+ position == recorded_reads_.back().offset +
recorded_reads_.back().length) {
+ // merge continuous IOs into one if possible
+ recorded_reads_.back().length += num_bytes_read;
+ } else {
+ // no real IO is performed, it is only saved into a vector for replaying
later
+ recorded_reads_.emplace_back(io::ReadRange{position, num_bytes_read});
+ }
+ return num_bytes_read;
+}
+
+Result<std::shared_ptr<Buffer>> IoRecordedRandomAccessFile::ReadAt(int64_t
position,
+ int64_t
nbytes) {
+ std::shared_ptr<Buffer> out;
+ auto result = ReadAt(position, nbytes, &out);
+ return out;
+}
+
+Status IoRecordedRandomAccessFile::Close() {
+ closed_ = true;
+ return Status::OK();
+}
+
+Status IoRecordedRandomAccessFile::Abort() { return Status::OK(); }
+
+Result<int64_t> IoRecordedRandomAccessFile::Tell() const { return position_; }
+
+bool IoRecordedRandomAccessFile::closed() const { return closed_; }
+
+Status IoRecordedRandomAccessFile::Seek(int64_t position) {
+ position_ = position;
+ return Status::OK();
+}
+
+Result<int64_t> IoRecordedRandomAccessFile::Read(int64_t nbytes, void* out) {
+ return ReadAt(position_, nbytes, out);
+}
+
+Result<std::shared_ptr<Buffer>> IoRecordedRandomAccessFile::Read(int64_t
nbytes) {
+ return ReadAt(position_, nbytes);
+}
+
+const io::IOContext& IoRecordedRandomAccessFile::io_context() const {
+ return io_context_;
+}
+
+const std::vector<io::ReadRange>&
IoRecordedRandomAccessFile::GetRecordedReads() const {
Review comment:
I find arrow has a class `io::ReadRange` with offset/length in it, and
its semantics fit this API very well, so I re-use this class in the API instead
of `std::pair<int64_t, int64_t>`
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