feat: Add support for IO[bytes] and bytes in scan_{...} functions

crates/polars-io/src/csv/read/mod.rs

@@ -26,7 +26,7 @@ mod splitfields;
 mod utils;
 
 pub use options::{CommentPrefix, CsvEncoding, CsvParseOptions, CsvReadOptions, NullValues};
-pub use parser::count_rows;
+pub use parser::{count_rows, count_rows_from_slice};
 pub use read_impl::batched::{BatchedCsvReader, OwnedBatchedCsvReader};
 pub use reader::CsvReader;
 pub use schema_inference::infer_file_schema;

crates/polars-io/src/csv/read/parser.rs

@@ -1,9 +1,10 @@
-use std::path::PathBuf;
+use std::path::Path;
 
 use memchr::memchr2_iter;
 use num_traits::Pow;
 use polars_core::prelude::*;
 use polars_core::{config, POOL};
+use polars_error::feature_gated;
 use polars_utils::index::Bounded;
 use polars_utils::slice::GetSaferUnchecked;
 use rayon::prelude::*;
@@ -18,71 +19,80 @@ use crate::utils::maybe_decompress_bytes;
 /// Read the number of rows without parsing columns
 /// useful for count(*) queries
 pub fn count_rows(
-    path: &PathBuf,
+    path: &Path,
     separator: u8,
     quote_char: Option<u8>,
     comment_prefix: Option<&CommentPrefix>,
     eol_char: u8,
     has_header: bool,
 ) -> PolarsResult<usize> {
     let file = if is_cloud_url(path) || config::force_async() {
-        #[cfg(feature = "cloud")]
-        {
+        feature_gated!("cloud", {
             crate::file_cache::FILE_CACHE
                 .get_entry(path.to_str().unwrap())
                 // Safety: This was initialized by schema inference.
                 .unwrap()
                 .try_open_assume_latest()?
-        }
-        #[cfg(not(feature = "cloud"))]
-        {
-            panic!("required feature `cloud` is not enabled")
-        }
+        })
     } else {
         polars_utils::open_file(path)?
     };
 
     let mmap = unsafe { memmap::Mmap::map(&file).unwrap() };
     let owned = &mut vec![];
-    let mut reader_bytes = maybe_decompress_bytes(mmap.as_ref(), owned)?;
+    let reader_bytes = maybe_decompress_bytes(mmap.as_ref(), owned)?;
 
-    for _ in 0..reader_bytes.len() {
-        if reader_bytes[0] != eol_char {
+    count_rows_from_slice(
+        reader_bytes,
+        separator,
+        quote_char,
+        comment_prefix,
+        eol_char,
+        has_header,
+    )
+}
+
+/// Read the number of rows without parsing columns
+/// useful for count(*) queries
+pub fn count_rows_from_slice(
+    mut bytes: &[u8],
+    separator: u8,
+    quote_char: Option<u8>,
+    comment_prefix: Option<&CommentPrefix>,
+    eol_char: u8,
+    has_header: bool,
+) -> PolarsResult<usize> {
+    for _ in 0..bytes.len() {
+        if bytes[0] != eol_char {
             break;
         }
 
-        reader_bytes = &reader_bytes[1..];
+        bytes = &bytes[1..];
     }
 
     const MIN_ROWS_PER_THREAD: usize = 1024;
     let max_threads = POOL.current_num_threads();
 
     // Determine if parallelism is beneficial and how many threads
     let n_threads = get_line_stats(
-        reader_bytes,
+        bytes,
         MIN_ROWS_PER_THREAD,
         eol_char,
         None,
         separator,
         quote_char,
     )
     .map(|(mean, std)| {
-        let n_rows = (reader_bytes.len() as f32 / (mean - 0.01 * std)) as usize;
+        let n_rows = (bytes.len() as f32 / (mean - 0.01 * std)) as usize;
         (n_rows / MIN_ROWS_PER_THREAD).clamp(1, max_threads)
     })
     .unwrap_or(1);
 
-    let file_chunks: Vec<(usize, usize)> = get_file_chunks(
-        reader_bytes,
-        n_threads,
-        None,
-        separator,
-        quote_char,
-        eol_char,
-    );
+    let file_chunks: Vec<(usize, usize)> =
+        get_file_chunks(bytes, n_threads, None, separator, quote_char, eol_char);
 
     let iter = file_chunks.into_par_iter().map(|(start, stop)| {
-        let local_bytes = &reader_bytes[start..stop];
+        let local_bytes = &bytes[start..stop];
         let row_iterator = SplitLines::new(local_bytes, quote_char.unwrap_or(b'"'), eol_char);
         if comment_prefix.is_some() {
             Ok(row_iterator

crates/polars-io/src/ipc/ipc_file.rs

@@ -51,9 +51,7 @@ use crate::RowIndex;
 
 #[derive(Clone, Debug, PartialEq, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
-pub struct IpcScanOptions {
-    pub memory_map: bool,
-}
+pub struct IpcScanOptions;
 
 /// Read Arrows IPC format into a DataFrame
 ///

crates/polars-io/src/ipc/mmap.rs

@@ -3,9 +3,10 @@ use arrow::io::ipc::read::{Dictionaries, FileMetadata};
 use arrow::mmap::{mmap_dictionaries_unchecked, mmap_unchecked};
 use arrow::record_batch::RecordBatch;
 use polars_core::prelude::*;
+use polars_utils::mmap::MMapSemaphore;
 
 use super::ipc_file::IpcReader;
-use crate::mmap::{MMapSemaphore, MmapBytesReader};
+use crate::mmap::MmapBytesReader;
 use crate::predicates::PhysicalIoExpr;
 use crate::shared::{finish_reader, ArrowReader};
 use crate::utils::{apply_projection, columns_to_projection};
@@ -15,17 +16,9 @@ impl<R: MmapBytesReader> IpcReader<R> {
         &mut self,
         predicate: Option<Arc<dyn PhysicalIoExpr>>,
     ) -> PolarsResult<DataFrame> {
-        #[cfg(target_family = "unix")]
-        use std::os::unix::fs::MetadataExt;
         match self.reader.to_file() {
             Some(file) => {
-                #[cfg(target_family = "unix")]
-                let metadata = file.metadata()?;
-                let mmap = unsafe { memmap::Mmap::map(file).unwrap() };
-                #[cfg(target_family = "unix")]
-                let semaphore = MMapSemaphore::new(metadata.dev(), metadata.ino(), mmap);
-                #[cfg(not(target_family = "unix"))]
-                let semaphore = MMapSemaphore::new(mmap);
+                let semaphore = MMapSemaphore::new_from_file(file)?;
                 let metadata =
                     read::read_file_metadata(&mut std::io::Cursor::new(semaphore.as_ref()))?;
 

crates/polars-io/src/mmap.rs

@@ -1,84 +1,9 @@
-#[cfg(target_family = "unix")]
-use std::collections::btree_map::Entry;
-#[cfg(target_family = "unix")]
-use std::collections::BTreeMap;
 use std::fs::File;
 use std::io::{BufReader, Cursor, Read, Seek};
 use std::sync::Arc;
-#[cfg(target_family = "unix")]
-use std::sync::Mutex;
 
-use memmap::Mmap;
-#[cfg(target_family = "unix")]
-use once_cell::sync::Lazy;
 use polars_core::config::verbose;
-#[cfg(target_family = "unix")]
-use polars_error::polars_bail;
-use polars_error::PolarsResult;
-use polars_utils::mmap::MemSlice;
-
-// Keep track of memory mapped files so we don't write to them while reading
-// Use a btree as it uses less memory than a hashmap and this thing never shrinks.
-// Write handle in Windows is exclusive, so this is only necessary in Unix.
-#[cfg(target_family = "unix")]
-static MEMORY_MAPPED_FILES: Lazy<Mutex<BTreeMap<(u64, u64), u32>>> =
-    Lazy::new(|| Mutex::new(Default::default()));
-
-pub(crate) struct MMapSemaphore {
-    #[cfg(target_family = "unix")]
-    key: (u64, u64),
-    mmap: Mmap,
-}
-
-impl MMapSemaphore {
-    #[cfg(target_family = "unix")]
-    pub(super) fn new(dev: u64, ino: u64, mmap: Mmap) -> Self {
-        let mut guard = MEMORY_MAPPED_FILES.lock().unwrap();
-        let key = (dev, ino);
-        guard.insert(key, 1);
-        Self { key, mmap }
-    }
-
-    #[cfg(not(target_family = "unix"))]
-    pub(super) fn new(mmap: Mmap) -> Self {
-        Self { mmap }
-    }
-}
-
-impl AsRef<[u8]> for MMapSemaphore {
-    #[inline]
-    fn as_ref(&self) -> &[u8] {
-        self.mmap.as_ref()
-    }
-}
-
-#[cfg(target_family = "unix")]
-impl Drop for MMapSemaphore {
-    fn drop(&mut self) {
-        let mut guard = MEMORY_MAPPED_FILES.lock().unwrap();
-        if let Entry::Occupied(mut e) = guard.entry(self.key) {
-            let v = e.get_mut();
-            *v -= 1;
-
-            if *v == 0 {
-                e.remove_entry();
-            }
-        }
-    }
-}
-
-pub fn ensure_not_mapped(#[allow(unused)] file: &File) -> PolarsResult<()> {
-    #[cfg(target_family = "unix")]
-    {
-        use std::os::unix::fs::MetadataExt;
-        let guard = MEMORY_MAPPED_FILES.lock().unwrap();
-        let metadata = file.metadata()?;
-        if guard.contains_key(&(metadata.dev(), metadata.ino())) {
-            polars_bail!(ComputeError: "cannot write to file: already memory mapped");
-        }
-    }
-    Ok(())
-}
+use polars_utils::mmap::{MMapSemaphore, MemSlice};
 
 /// Trait used to get a hold to file handler or to the underlying bytes
 /// without performing a Read.
@@ -104,6 +29,12 @@ impl MmapBytesReader for BufReader<File> {
     }
 }
 
+impl MmapBytesReader for BufReader<&File> {
+    fn to_file(&self) -> Option<&File> {
+        Some(self.get_ref())
+    }
+}
+
 impl<T> MmapBytesReader for Cursor<T>
 where
     T: AsRef<[u8]> + Send + Sync,
@@ -137,7 +68,7 @@ impl<T: MmapBytesReader> MmapBytesReader for &mut T {
 pub enum ReaderBytes<'a> {
     Borrowed(&'a [u8]),
     Owned(Vec<u8>),
-    Mapped(memmap::Mmap, &'a File),
+    Mapped(MMapSemaphore, &'a File),
 }
 
 impl std::ops::Deref for ReaderBytes<'_> {
@@ -146,7 +77,7 @@ impl std::ops::Deref for ReaderBytes<'_> {
         match self {
             Self::Borrowed(ref_bytes) => ref_bytes,
             Self::Owned(vec) => vec,
-            Self::Mapped(mmap, _) => mmap,
+            Self::Mapped(mmap, _) => mmap.as_ref(),
         }
     }
 }
@@ -174,7 +105,7 @@ impl<'a, T: 'a + MmapBytesReader> From<&'a mut T> for ReaderBytes<'a> {
             None => {
                 if let Some(f) = m.to_file() {
                     let f = unsafe { std::mem::transmute::<&File, &'a File>(f) };
-                    let mmap = unsafe { memmap::Mmap::map(f).unwrap() };
+                    let mmap = MMapSemaphore::new_from_file(f).unwrap();
                     ReaderBytes::Mapped(mmap, f)
                 } else {
                     if verbose() {

crates/polars-io/src/path_utils/mod.rs

@@ -88,7 +88,7 @@ pub fn expand_paths(
     paths: &[PathBuf],
     glob: bool,
     #[allow(unused_variables)] cloud_options: Option<&CloudOptions>,
-) -> PolarsResult<Arc<Vec<PathBuf>>> {
+) -> PolarsResult<Arc<[PathBuf]>> {
     expand_paths_hive(paths, glob, cloud_options, false).map(|x| x.0)
 }
 
@@ -129,7 +129,7 @@ pub fn expand_paths_hive(
     glob: bool,
     #[allow(unused_variables)] cloud_options: Option<&CloudOptions>,
     check_directory_level: bool,
-) -> PolarsResult<(Arc<Vec<PathBuf>>, usize)> {
+) -> PolarsResult<(Arc<[PathBuf]>, usize)> {
     let Some(first_path) = paths.first() else {
         return Ok((vec![].into(), 0));
     };
@@ -361,7 +361,7 @@ pub fn expand_paths_hive(
         out_paths
     };
 
-    Ok((Arc::new(out_paths), hive_idx_tracker.idx))
+    Ok((out_paths.into(), hive_idx_tracker.idx))
 }
 
 /// Ignores errors from `std::fs::create_dir_all` if the directory exists.

crates/polars-io/src/utils/byte_source.rs

@@ -1,7 +1,7 @@
 use std::ops::Range;
 use std::sync::Arc;
 
-use polars_error::{to_compute_err, PolarsResult};
+use polars_error::PolarsResult;
 use polars_utils::_limit_path_len_io_err;
 use polars_utils::mmap::MemSlice;
 
@@ -34,9 +34,8 @@ impl MemSliceByteSource {
                 .into_std()
                 .await,
         );
-        let mmap = Arc::new(unsafe { memmap::Mmap::map(file.as_ref()) }.map_err(to_compute_err)?);
 
-        Ok(Self(MemSlice::from_mmap(mmap)))
+        Ok(Self(MemSlice::from_file(file.as_ref())?))
     }
 }
 

crates/polars-io/src/utils/other.rs

@@ -7,6 +7,7 @@ use polars_core::prelude::*;
 #[cfg(any(feature = "ipc_streaming", feature = "parquet"))]
 use polars_core::utils::{accumulate_dataframes_vertical_unchecked, split_df_as_ref};
 use polars_error::to_compute_err;
+use polars_utils::mmap::MMapSemaphore;
 use regex::{Regex, RegexBuilder};
 
 use crate::mmap::{MmapBytesReader, ReaderBytes};
@@ -21,12 +22,15 @@ pub fn get_reader_bytes<'a, R: Read + MmapBytesReader + ?Sized>(
         .ok()
         .and_then(|offset| Some((reader.to_file()?, offset)))
     {
-        let mmap = unsafe { memmap::MmapOptions::new().offset(offset).map(file)? };
+        let mut options = memmap::MmapOptions::new();
+        options.offset(offset);
 
         // somehow bck thinks borrows alias
         // this is sound as file was already bound to 'a
         use std::fs::File;
+
         let file = unsafe { std::mem::transmute::<&File, &'a File>(file) };
+        let mmap = MMapSemaphore::new_from_file_with_options(file, options)?;
         Ok(ReaderBytes::Mapped(mmap, file))
     } else {
         // we can get the bytes for free

crates/polars-lazy/src/lib.rs

@@ -206,6 +206,7 @@ pub mod dsl;
 pub mod frame;
 pub mod physical_plan;
 pub mod prelude;
+
 mod scan;
 #[cfg(test)]
 mod tests;