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Posted to github@arrow.apache.org by GitBox <gi...@apache.org> on 2020/10/21 08:06:46 UTC
[GitHub] [arrow] rdettai commented on a change in pull request #8300: ARROW-10135: [Rust] [Parquet] Refactor file module to help adding sources
rdettai commented on a change in pull request #8300:
URL: https://github.com/apache/arrow/pull/8300#discussion_r509071560
##########
File path: rust/parquet/src/util/cursor.rs
##########
@@ -0,0 +1,203 @@
+// Licensed to the Apache Software Foundation (ASF) under one
Review comment:
this is intended
##########
File path: rust/parquet/src/file/serialized_reader.rs
##########
@@ -0,0 +1,747 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+//! Contains file reader implementations and provides methods to access file metadata, row group
Review comment:
I'll try to come up with something more explicit!
##########
File path: rust/parquet/src/file/reader.rs
##########
@@ -18,35 +18,37 @@
//! Contains file reader API and provides methods to access file metadata, row group
//! readers to read individual column chunks, or access record iterator.
-use std::{
- convert::TryFrom,
- fs::File,
- io::{BufReader, Cursor, Read, Seek, SeekFrom},
- path::Path,
- rc::Rc,
-};
+use std::{boxed::Box, io::Read, rc::Rc};
-use byteorder::{ByteOrder, LittleEndian};
-use parquet_format::{
- ColumnOrder as TColumnOrder, FileMetaData as TFileMetaData, PageHeader, PageType,
-};
-use thrift::protocol::TCompactInputProtocol;
-
-use crate::basic::{ColumnOrder, Compression, Encoding, Type};
use crate::column::page::PageIterator;
-use crate::column::{
- page::{Page, PageReader},
- reader::{ColumnReader, ColumnReaderImpl},
-};
-use crate::compression::{create_codec, Codec};
+use crate::column::{page::PageReader, reader::ColumnReader};
use crate::errors::{ParquetError, Result};
-use crate::file::{metadata::*, statistics, FOOTER_SIZE, PARQUET_MAGIC};
+use crate::file::metadata::*;
+pub use crate::file::serialized_reader::{SerializedFileReader, SerializedPageReader};
use crate::record::reader::RowIter;
-use crate::record::Row;
-use crate::schema::types::{
- self, ColumnDescPtr, SchemaDescPtr, SchemaDescriptor, Type as SchemaType,
-};
-use crate::util::{io::FileSource, memory::ByteBufferPtr};
+use crate::schema::types::{ColumnDescPtr, SchemaDescPtr, Type as SchemaType};
+
+use crate::basic::Type;
+
+use crate::column::reader::ColumnReaderImpl;
+
+/// Length should return the total number of bytes in the input source.
+/// It's mainly used to read the metadata, which is at the end of the source.
+#[allow(clippy::len_without_is_empty)]
+pub trait Length {
+ /// Returns the amount of bytes of the inner source.
+ fn len(&self) -> u64;
+}
+
+/// The ChunkReader trait generates readers of chunks of a source.
+/// For a file system reader, each chunk might contain a clone of File bounded on a given range.
+/// For an object store reader, each read can be mapped to a range request.
+pub trait ChunkReader: Length {
Review comment:
I used *Reader* because it does not implem `Read` but generates things that implem `Read`. But I admit that I'm not 100% happy with `ChunkReader` and it would be nice to have something more explicit as this is a very public part of the API.
##########
File path: rust/parquet/src/util/cursor.rs
##########
@@ -0,0 +1,203 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+use std::cmp;
+use std::io::{self, Error, ErrorKind, Read, Seek, SeekFrom};
+use std::rc::Rc;
+
+/// This is object to use if your file is already in memory.
+/// The sliceable cursor is similar to std::io::Cursor, except that it makes it easy to create "cursor slices".
+/// To achieve this, it uses Rc instead of shared references. Indeed reference fields are painfull
Review comment:
This is not a new feature but an adaptation of what we had before. Without `SliceableCursor` their is now way to read from RAM the way it was done with `Cursor`. It is just that instead of directly implementing the new `ChunkReader` trait for `Cursor` and having the same problem of copying the data all over the place as we did before, I tweeked the Cursor a bit to share its data between the `Read` slices.
##########
File path: rust/parquet/src/file/reader.rs
##########
@@ -18,35 +18,37 @@
//! Contains file reader API and provides methods to access file metadata, row group
//! readers to read individual column chunks, or access record iterator.
-use std::{
- convert::TryFrom,
- fs::File,
- io::{BufReader, Cursor, Read, Seek, SeekFrom},
- path::Path,
- rc::Rc,
-};
+use std::{boxed::Box, io::Read, rc::Rc};
-use byteorder::{ByteOrder, LittleEndian};
-use parquet_format::{
- ColumnOrder as TColumnOrder, FileMetaData as TFileMetaData, PageHeader, PageType,
-};
-use thrift::protocol::TCompactInputProtocol;
-
-use crate::basic::{ColumnOrder, Compression, Encoding, Type};
use crate::column::page::PageIterator;
-use crate::column::{
- page::{Page, PageReader},
- reader::{ColumnReader, ColumnReaderImpl},
-};
-use crate::compression::{create_codec, Codec};
+use crate::column::{page::PageReader, reader::ColumnReader};
use crate::errors::{ParquetError, Result};
-use crate::file::{metadata::*, statistics, FOOTER_SIZE, PARQUET_MAGIC};
+use crate::file::metadata::*;
+pub use crate::file::serialized_reader::{SerializedFileReader, SerializedPageReader};
use crate::record::reader::RowIter;
-use crate::record::Row;
-use crate::schema::types::{
- self, ColumnDescPtr, SchemaDescPtr, SchemaDescriptor, Type as SchemaType,
-};
-use crate::util::{io::FileSource, memory::ByteBufferPtr};
+use crate::schema::types::{ColumnDescPtr, SchemaDescPtr, Type as SchemaType};
+
+use crate::basic::Type;
+
+use crate::column::reader::ColumnReaderImpl;
+
+/// Length should return the total number of bytes in the input source.
+/// It's mainly used to read the metadata, which is at the end of the source.
+#[allow(clippy::len_without_is_empty)]
+pub trait Length {
Review comment:
I think not because because it is also used by `ChunkReader` and io.rs contains internal implementations. But I admit that I still don't have it very clear how modules should be structured in Rust 😄
##########
File path: rust/parquet/src/file/footer.rs
##########
@@ -0,0 +1,266 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+//! Contains file reader API and provides methods to access file metadata, row group
Review comment:
Thanks, slipped away.
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