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. The majority of the `from` calls in here are safe/loss-less conversions but there are a couple that are not (where I use `try_from`) and I like being able to see that clearly in the code. Also, the `from` calls provide compile-time safety which is useful in case anyone decides to change the type of any of these constants in the future which could result in an unsafe/lossy cast if we use `as`. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@iceberg.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@iceberg.apache.org For additional commands, e-mail: issues-h...@iceberg.apache.org
