fqaiser94 commented on code in PR #765: URL: https://github.com/apache/iceberg-rust/pull/765#discussion_r1885103610
########## crates/iceberg/src/puffin/metadata.rs: ########## @@ -0,0 +1,809 @@ +// 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::collections::{HashMap, HashSet}; + +use bytes::Bytes; +use once_cell::sync::Lazy; +use serde::{Deserialize, Serialize}; + +use crate::io::{FileRead, InputFile}; +use crate::puffin::compression::CompressionCodec; +use crate::{Error, ErrorKind, Result}; + +/// Human-readable identification of the application writing the file, along with its version. +/// Example: "Trino version 381" +pub(crate) const CREATED_BY_PROPERTY: &str = "created-by"; + +#[derive(Debug, PartialEq, Eq, Serialize, Deserialize, Clone)] +#[serde(rename_all = "kebab-case")] +/// Metadata about a blob. +/// For more information, see: https://iceberg.apache.org/puffin-spec/#blobmetadata +pub(crate) struct BlobMetadata { + /// See blob types: https://iceberg.apache.org/puffin-spec/#blob-types + pub(crate) r#type: String, + /// List of field IDs the blob was computed for; the order of items is used to compute sketches stored in the blob. + #[serde(rename = "fields")] + pub(crate) input_fields: Vec<i32>, + /// ID of the Iceberg table's snapshot the blob was computed from + pub(crate) snapshot_id: i64, + /// Sequence number of the Iceberg table's snapshot the blob was computed from + pub(crate) sequence_number: i64, + /// The offset in the file where the blob contents start + pub(crate) offset: u64, + /// The length of the blob stored in the file (after compression, if compressed) + pub(crate) length: usize, + /// The compression codec used to compress the data + #[serde(skip_serializing_if = "CompressionCodec::is_none")] + #[serde(default)] + pub(crate) compression_codec: CompressionCodec, + /// Arbitrary meta-information about the blob + #[serde(skip_serializing_if = "HashMap::is_empty")] + #[serde(default)] + pub(crate) properties: HashMap<String, String>, +} + +#[derive(Clone, PartialEq, Eq, Hash, Debug)] +pub(crate) enum Flag { + FooterPayloadCompressed, +} + +#[derive(PartialEq, Eq, Hash)] +pub(crate) struct ByteNumber(pub u8); + +#[derive(PartialEq, Eq, Hash)] +pub(crate) struct BitNumber(pub u8); + +static FLAGS_BY_BYTE_AND_BIT: Lazy<HashMap<(ByteNumber, BitNumber), Flag>> = Lazy::new(|| { + let mut m = HashMap::new(); + m.insert( + ( + Flag::FooterPayloadCompressed.byte_number(), + Flag::FooterPayloadCompressed.bit_number(), + ), + Flag::FooterPayloadCompressed, + ); + m +}); + +impl Flag { + pub(crate) fn byte_number(&self) -> ByteNumber { + match self { + Flag::FooterPayloadCompressed => ByteNumber(0), + } + } + + pub(crate) fn bit_number(&self) -> BitNumber { + match self { + Flag::FooterPayloadCompressed => BitNumber(0), + } + } + + fn from(byte_and_bit: &(ByteNumber, BitNumber)) -> Option<Flag> { + FLAGS_BY_BYTE_AND_BIT.get(byte_and_bit).cloned() + } +} + +#[derive(Debug, PartialEq, Eq, Serialize, Deserialize, Clone)] +/// Metadata about a puffin file. +/// For more information, see: https://iceberg.apache.org/puffin-spec/#filemetadata +pub(crate) struct FileMetadata { + /// Metadata about blobs in file + pub(crate) blobs: Vec<BlobMetadata>, + #[serde(skip_serializing_if = "HashMap::is_empty")] + #[serde(default)] + /// Arbitrary meta-information, like writer identification/version. + pub(crate) properties: HashMap<String, String>, +} + +impl FileMetadata { + pub(crate) const MAGIC_LENGTH: u8 = 4; + pub(crate) const MAGIC: [u8; FileMetadata::MAGIC_LENGTH as usize] = [0x50, 0x46, 0x41, 0x31]; + + // We use the term FOOTER_STRUCT to refer to the fixed-length portion of the Footer, as illustrated below. + // + // Footer + // | + // ------------------------------------------------- + // | | + // Magic FooterPayload FooterPayloadLength Flags Magic + // | | + // ----------------------------- + // | + // FOOTER_STRUCT + + const FOOTER_STRUCT_PAYLOAD_LENGTH_OFFSET: u8 = 0; + const FOOTER_STRUCT_PAYLOAD_LENGTH_LENGTH: u8 = 4; + const FOOTER_STRUCT_FLAGS_OFFSET: u8 = FileMetadata::FOOTER_STRUCT_PAYLOAD_LENGTH_OFFSET + + FileMetadata::FOOTER_STRUCT_PAYLOAD_LENGTH_LENGTH; + pub(crate) const FOOTER_STRUCT_FLAGS_LENGTH: u8 = 4; + const FOOTER_STRUCT_MAGIC_OFFSET: u8 = + FileMetadata::FOOTER_STRUCT_FLAGS_OFFSET + FileMetadata::FOOTER_STRUCT_FLAGS_LENGTH; + pub(crate) const FOOTER_STRUCT_LENGTH: u8 = + FileMetadata::FOOTER_STRUCT_MAGIC_OFFSET + FileMetadata::MAGIC_LENGTH; + + fn check_magic(bytes: &[u8]) -> Result<()> { + if bytes != FileMetadata::MAGIC { + Err(Error::new( + ErrorKind::DataInvalid, + format!( + "Bad magic value: {:?} should be {:?}", + bytes, + FileMetadata::MAGIC + ), + )) + } else { + Ok(()) + } + } + + async fn read_footer_payload_length( + file_read: &dyn FileRead, + input_file_length: u64, + ) -> Result<u32> { + let start = input_file_length - u64::from(FileMetadata::FOOTER_STRUCT_LENGTH); Review Comment: I can make this change if you insist but my understanding is that [`as` can be dangerous](https://www.reddit.com/r/rust/comments/w8nxi9/should_as_casts_be_avoided/) and for that reason I would prefer to avoid. -- This is an automated message from the Apache Git Service. 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