Make file reading thread-safe, by having SubFile use read_at/seek_read rather than seek and read.

src/data/iterators.rs

@@ -1,4 +1,4 @@
-use std::{fmt::Display, fs::File};
+use std::fmt::Display;
 
 use chrono::{DateTime, NaiveDate, Utc};
 
@@ -241,14 +241,11 @@ impl Iterator for Vectors {
 #[derive(Debug)]
 pub struct GenericBoundaries<T: NumberType> {
     value: BoundaryValues<T>,
-    inclusive: SimpleIter<bool, SubFile<File>>,
+    inclusive: SimpleIter<bool, SubFile>,
 }
 
 impl<T: NumberType> GenericBoundaries<T> {
-    pub fn new(
-        value: SimpleIter<T, SubFile<File>>,
-        inclusive: SimpleIter<bool, SubFile<File>>,
-    ) -> Self {
+    pub fn new(value: SimpleIter<T, SubFile>, inclusive: SimpleIter<bool, SubFile>) -> Self {
         Self {
             value: BoundaryValues::new(value),
             inclusive,

src/data/read_checks.rs

@@ -1,4 +1,4 @@
-use std::{collections::HashSet, fs::File};
+use std::collections::HashSet;
 
 use crate::{
     array::Constraint,
@@ -18,12 +18,12 @@ use super::{
 /// When used for tensor block model sizes this checks that all sizes are greater than zero.
 #[derive(Debug)]
 pub struct GenericScalars<T: FloatType> {
-    inner: SimpleIter<T, SubFile<File>>,
+    inner: SimpleIter<T, SubFile>,
     is_size: bool,
 }
 
 impl<T: FloatType> GenericScalars<T> {
-    pub(crate) fn new(inner: SimpleIter<T, SubFile<File>>, constraint: &Constraint) -> Self {
+    pub(crate) fn new(inner: SimpleIter<T, SubFile>, constraint: &Constraint) -> Self {
         Self {
             inner,
             is_size: matches!(constraint, Constraint::Size),
@@ -55,12 +55,12 @@ impl<T: FloatType> Iterator for GenericScalars<T> {
 /// Checks that all indices are within range.
 #[derive(Debug)]
 pub struct Indices {
-    inner: NullableIter<u32, SubFile<File>>,
+    inner: NullableIter<u32, SubFile>,
     category_count: u64,
 }
 
 impl Indices {
-    pub(crate) fn new(inner: NullableIter<u32, SubFile<File>>, constraint: &Constraint) -> Self {
+    pub(crate) fn new(inner: NullableIter<u32, SubFile>, constraint: &Constraint) -> Self {
         let &Constraint::Index(category_count) = constraint else {
             panic!("invalid constraint");
         };
@@ -95,12 +95,12 @@ impl Iterator for Indices {
 /// Checks that all vertex indices are within range.
 #[derive(Debug)]
 pub struct GenericPrimitives<const N: usize> {
-    inner: MultiIter<u32, SubFile<File>, N>,
+    inner: MultiIter<u32, SubFile, N>,
     vertex_count: u64,
 }
 
 impl<const N: usize> GenericPrimitives<N> {
-    pub(crate) fn new(inner: MultiIter<u32, SubFile<File>, N>, constraint: &Constraint) -> Self {
+    pub(crate) fn new(inner: MultiIter<u32, SubFile, N>, constraint: &Constraint) -> Self {
         let vertex_count = match constraint {
             Constraint::Segment(n) | Constraint::Triangle(n) => *n,
             _ => panic!("invalid constraint"),
@@ -138,12 +138,12 @@ impl<const N: usize> Iterator for GenericPrimitives<N> {
 /// Checks that the values are increasing.
 #[derive(Debug)]
 pub(super) struct BoundaryValues<T: NumberType> {
-    inner: SimpleIter<T, SubFile<File>>,
+    inner: SimpleIter<T, SubFile>,
     previous: Option<T>,
 }
 
 impl<T: NumberType> BoundaryValues<T> {
-    pub(crate) fn new(inner: SimpleIter<T, SubFile<File>>) -> Self {
+    pub(crate) fn new(inner: SimpleIter<T, SubFile>) -> Self {
         Self {
             inner,
             previous: None,
@@ -170,15 +170,15 @@ impl<T: NumberType> Iterator for BoundaryValues<T> {
 /// Checks that the parent index and corners are all valid.
 #[derive(Debug)]
 pub struct GenericFreeformSubblocks<T: FloatType> {
-    parents: MultiIter<u32, SubFile<File>, 3>,
-    corners: MultiIter<T, SubFile<File>, 6>,
+    parents: MultiIter<u32, SubFile, 3>,
+    corners: MultiIter<T, SubFile, 6>,
     block_count: [u32; 3],
 }
 
 impl<T: FloatType> GenericFreeformSubblocks<T> {
     pub(crate) fn new(
-        parents: MultiIter<u32, SubFile<File>, 3>,
-        corners: MultiIter<T, SubFile<File>, 6>,
+        parents: MultiIter<u32, SubFile, 3>,
+        corners: MultiIter<T, SubFile, 6>,
         constraint: &Constraint,
     ) -> Self {
         let block_count = match constraint {
@@ -219,17 +219,17 @@ impl<T: FloatType> Iterator for GenericFreeformSubblocks<T> {
 /// Checks that the parent index and corners are all valid.
 #[derive(Debug)]
 pub struct RegularSubblocks {
-    parents: MultiIter<u32, SubFile<File>, 3>,
-    corners: MultiIter<u32, SubFile<File>, 6>,
+    parents: MultiIter<u32, SubFile, 3>,
+    corners: MultiIter<u32, SubFile, 6>,
     block_count: [u32; 3],
     subblock_count: [u32; 3],
     mode: Option<(SubblockMode, HashSet<[u32; 3]>)>,
 }
 
 impl RegularSubblocks {
     pub(crate) fn new(
-        parents: MultiIter<u32, SubFile<File>, 3>,
-        corners: MultiIter<u32, SubFile<File>, 6>,
+        parents: MultiIter<u32, SubFile, 3>,
+        corners: MultiIter<u32, SubFile, 6>,
         constraint: &Constraint,
     ) -> Self {
         let &Constraint::RegularSubblock {
@@ -350,7 +350,7 @@ fn check_freeform_corners<T: FloatType>(corners: [T; 6]) -> Result<(), Error> {
 
 /// Iterator for reading numbers, supporting `f32`, `f64`, `i64`, date, and date-time generically.
 #[derive(Debug)]
-pub struct GenericNumbers<T: NumberType>(pub(crate) NullableIter<T, SubFile<File>>);
+pub struct GenericNumbers<T: NumberType>(pub(crate) NullableIter<T, SubFile>);
 
 impl<T: NumberType> Iterator for GenericNumbers<T> {
     type Item = Result<Option<T>, Error>;
@@ -362,7 +362,7 @@ impl<T: NumberType> Iterator for GenericNumbers<T> {
 
 /// Iterator for reading small fixed-size arrays, like vertices and texture coordinates.
 #[derive(Debug)]
-pub struct GenericArrays<T: NumberType, const N: usize>(pub(crate) MultiIter<T, SubFile<File>, N>);
+pub struct GenericArrays<T: NumberType, const N: usize>(pub(crate) MultiIter<T, SubFile, N>);
 
 impl<T: NumberType, const N: usize> Iterator for GenericArrays<T, N> {
     type Item = Result<[T; N], Error>;
@@ -374,7 +374,7 @@ impl<T: NumberType, const N: usize> Iterator for GenericArrays<T, N> {
 
 /// Iterator for reading non-nullable colors, such as category legends.
 #[derive(Debug)]
-pub struct Gradient(pub(crate) MultiIter<u8, SubFile<File>, 4>);
+pub struct Gradient(pub(crate) MultiIter<u8, SubFile, 4>);
 
 impl Iterator for Gradient {
     type Item = Result<[u8; 4], Error>;
@@ -387,7 +387,7 @@ impl Iterator for Gradient {
 /// Iterator for reading small optional fixed-size arrays, like 2D and 3D vectors.
 #[derive(Debug)]
 pub struct GenericOptionalArrays<T: NumberType, const N: usize>(
-    pub(crate) NullableGroupIter<T, SubFile<File>, N>,
+    pub(crate) NullableGroupIter<T, SubFile, N>,
 );
 
 impl<T: NumberType, const N: usize> Iterator for GenericOptionalArrays<T, N> {
@@ -400,7 +400,7 @@ impl<T: NumberType, const N: usize> Iterator for GenericOptionalArrays<T, N> {
 
 /// Iterator for reading nullable colors.
 #[derive(Debug)]
-pub struct Colors(pub(crate) NullableGroupIter<u8, SubFile<File>, 4>);
+pub struct Colors(pub(crate) NullableGroupIter<u8, SubFile, 4>);
 
 impl Iterator for Colors {
     type Item = Result<Option<[u8; 4]>, Error>;
@@ -412,7 +412,7 @@ impl Iterator for Colors {
 
 /// Iterator for reading nullable booleans.
 #[derive(Debug)]
-pub struct Booleans(pub(crate) NullableIter<bool, SubFile<File>>);
+pub struct Booleans(pub(crate) NullableIter<bool, SubFile>);
 
 impl Iterator for Booleans {
     type Item = Result<Option<bool>, Error>;
@@ -424,7 +424,7 @@ impl Iterator for Booleans {
 
 /// Iterator for reading non-nullable strings, such as category names.
 #[derive(Debug)]
-pub struct Names(pub(crate) SimpleIter<String, SubFile<File>>);
+pub struct Names(pub(crate) SimpleIter<String, SubFile>);
 
 impl Iterator for Names {
     type Item = Result<String, Error>;
@@ -436,7 +436,7 @@ impl Iterator for Names {
 
 /// Iterator for reading nullable strings.
 #[derive(Debug)]
-pub struct Text(pub(crate) NullableIter<String, SubFile<File>>);
+pub struct Text(pub(crate) NullableIter<String, SubFile>);
 
 impl Iterator for Text {
     type Item = Result<Option<String>, Error>;

src/file/parquet/reader.rs

@@ -1,5 +1,3 @@
-use std::fs::File;
-
 use crate::{
     array_type,
     data::*,
@@ -12,10 +10,7 @@ use crate::{
 use super::{super::Reader, schemas};
 
 impl Reader {
-    fn array_reader(
-        &self,
-        array: &Array<impl ArrayType>,
-    ) -> Result<PqArrayReader<SubFile<File>>, Error> {
+    fn array_reader(&self, array: &Array<impl ArrayType>) -> Result<PqArrayReader<SubFile>, Error> {
         let f = self.array_bytes_reader(array)?;
         let reader = PqArrayReader::new(f)?;
         if array.item_count() != reader.len() {

src/file/parquet/schemas.rs

@@ -1,4 +1,4 @@
-use std::{fs::File, sync::OnceLock};
+use std::sync::OnceLock;
 
 use crate::{
     file::SubFile,
@@ -23,7 +23,7 @@ macro_rules! declare_schema {
             }
 
             pub fn check(
-                reader: &PqArrayReader<SubFile<File>>,
+                reader: &PqArrayReader<SubFile>,
             ) -> Result<$name, crate::error::Error> {
                 reader.matches(Self::matcher())
             }

src/file/reader.rs

@@ -86,7 +86,6 @@ impl Default for Limits {
 /// > where data is maliciously crafted to expand to an excessive size when decompressed,
 /// > leading to a potential denial of service attack.
 /// > Use the limits provided check arrays sizes before allocating memory.
-
 pub struct Reader {
     archive: Archive,
     version: [u32; 2],
@@ -175,7 +174,7 @@ impl Reader {
     pub fn array_bytes_reader(
         &self,
         array: &array::Array<impl array::ArrayType>,
-    ) -> Result<SubFile<File>, Error> {
+    ) -> Result<SubFile, Error> {
         array.constraint(); // Check that validation has been done.
         self.archive.open(array.filename())
     }