vortex_file/footer/
mod.rs

1// SPDX-License-Identifier: Apache-2.0
2// SPDX-FileCopyrightText: Copyright the Vortex contributors
3
4//! Vortex file footer metadata.
5//!
6//! A footer contains the root layout, file-level statistics, the segment map, and the read contexts
7//! needed to resolve array/layout encoding ids during deserialization.
8//!
9//! The byte-level footer and postscript layout is part of the file-format spec; this module exposes
10//! the structured Rust representation and serializer/deserializer state machine.
11mod field_sizes;
12mod file_layout;
13mod file_statistics;
14mod postscript;
15mod segment;
16
17use std::sync::Arc;
18
19mod serializer;
20pub use serializer::*;
21mod deserializer;
22pub use deserializer::*;
23pub use field_sizes::CompressedFieldSizes;
24pub use file_statistics::FileStatistics;
25use flatbuffers::root;
26use itertools::Itertools;
27pub use segment::*;
28use vortex_array::ArrayId;
29use vortex_array::dtype::DType;
30use vortex_buffer::ByteBuffer;
31use vortex_error::VortexResult;
32use vortex_error::vortex_bail;
33use vortex_error::vortex_err;
34use vortex_flatbuffers::FlatBuffer;
35use vortex_flatbuffers::footer as fb;
36use vortex_layout::LayoutEncodingId;
37use vortex_layout::LayoutRef;
38use vortex_layout::layout_from_flatbuffer_with_options;
39use vortex_session::VortexSession;
40use vortex_session::registry::ReadContext;
41
42/// Captures the layout information of a Vortex file.
43#[derive(Debug, Clone)]
44pub struct Footer {
45    root_layout: LayoutRef,
46    segments: Arc<[SegmentSpec]>,
47    statistics: Option<FileStatistics>,
48    // The specific arrays used within the file, in the order they were registered.
49    array_read_ctx: ReadContext,
50    // The approximate size of the footer in bytes, used for caching and memory management.
51    approx_byte_size: Option<usize>,
52}
53
54impl Footer {
55    pub fn new(
56        root_layout: LayoutRef,
57        segments: Arc<[SegmentSpec]>,
58        statistics: Option<FileStatistics>,
59        array_read_ctx: ReadContext,
60    ) -> Self {
61        Self {
62            root_layout,
63            segments,
64            statistics,
65            array_read_ctx,
66            approx_byte_size: None,
67        }
68    }
69
70    pub(crate) fn with_approx_byte_size(mut self, approx_byte_size: usize) -> Self {
71        self.approx_byte_size = Some(approx_byte_size);
72        self
73    }
74
75    /// Read the [`Footer`] from a flatbuffer.
76    pub(crate) fn from_flatbuffer(
77        footer_bytes: FlatBuffer,
78        layout_bytes: FlatBuffer,
79        dtype: DType,
80        statistics: Option<FileStatistics>,
81        session: &VortexSession,
82    ) -> VortexResult<Self> {
83        let approx_byte_size = footer_bytes.len() + layout_bytes.len();
84        let fb_footer = root::<fb::Footer>(&footer_bytes)?;
85
86        // Create a LayoutContext from the registry.
87        let layout_specs = fb_footer.layout_specs();
88        #[expect(clippy::disallowed_methods, reason = "interning a dynamic id")]
89        let layout_ids: Arc<[_]> = layout_specs
90            .iter()
91            .flat_map(|e| e.iter())
92            .map(|encoding| LayoutEncodingId::new(encoding.id()))
93            .collect();
94        let layout_read_ctx = ReadContext::new(layout_ids);
95
96        // Create an ArrayContext from the registry.
97        let array_specs = fb_footer.array_specs();
98        #[expect(clippy::disallowed_methods, reason = "interning a dynamic id")]
99        let array_ids: Arc<[_]> = array_specs
100            .iter()
101            .flat_map(|e| e.iter())
102            .map(|encoding| ArrayId::new(encoding.id()))
103            .collect();
104        let array_read_ctx = ReadContext::new(array_ids);
105
106        let root_layout = layout_from_flatbuffer_with_options(
107            layout_bytes,
108            &dtype,
109            &layout_read_ctx,
110            &array_read_ctx,
111            session,
112            session.allows_unknown(),
113        )?;
114
115        let segments: Arc<[SegmentSpec]> = fb_footer
116            .segment_specs()
117            .ok_or_else(|| vortex_err!("FileLayout missing segment specs"))?
118            .iter()
119            .map(SegmentSpec::try_from)
120            .try_collect()?;
121
122        // Note this assertion is `<=` since we allow zero-length segments
123        if !segments.is_sorted_by_key(|segment| segment.offset) {
124            vortex_bail!("Segment offsets are not ordered");
125        }
126
127        Ok(Self {
128            root_layout,
129            segments,
130            statistics,
131            array_read_ctx,
132            approx_byte_size: Some(approx_byte_size),
133        })
134    }
135
136    /// Returns the root [`LayoutRef`] of the file.
137    pub fn layout(&self) -> &LayoutRef {
138        &self.root_layout
139    }
140
141    /// Returns the segment map of the file.
142    pub fn segment_map(&self) -> &Arc<[SegmentSpec]> {
143        &self.segments
144    }
145
146    /// Returns the statistics of the file.
147    pub fn statistics(&self) -> Option<&FileStatistics> {
148        self.statistics.as_ref()
149    }
150
151    /// Computes the compressed size in bytes of every field in the file, keyed by field path.
152    ///
153    /// Sizes are derived by attributing each segment in the [segment map][Self::segment_map] to a
154    /// field in the [layout tree][Self::layout]; see [`CompressedFieldSizes`] for the exact
155    /// attribution semantics. No IO is performed.
156    pub fn compressed_field_sizes(&self) -> VortexResult<CompressedFieldSizes> {
157        CompressedFieldSizes::try_new(&self.root_layout, &self.segments)
158    }
159
160    /// Returns the [`DType`] of the file.
161    pub fn dtype(&self) -> &DType {
162        self.root_layout.dtype()
163    }
164
165    /// Returns the approximate size of the footer in bytes, used for caching and memory management.
166    pub fn approx_byte_size(&self) -> Option<usize> {
167        self.approx_byte_size
168    }
169
170    /// Returns the number of rows in the file.
171    pub fn row_count(&self) -> u64 {
172        self.root_layout.row_count()
173    }
174
175    /// Returns a serializer for this footer.
176    pub fn into_serializer(self) -> FooterSerializer {
177        FooterSerializer::new(self)
178    }
179
180    /// Create a deserializer for a Vortex file footer.
181    pub fn deserializer(eof_buffer: ByteBuffer, session: VortexSession) -> FooterDeserializer {
182        FooterDeserializer::new(eof_buffer, session)
183    }
184}
vortex_file/footer/mod.rs

vortex_file/footer/
mod.rs
