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0.18 primitive: rename crate::io::Writer → WritebackFile

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The type's job is the bounded-cache writeback pipeline (sync_file_range
+ posix_fadvise(DONTNEED)) — not generic writing. The 0.17 name was
ambiguous; reading `Writer::new(file)` gave no hint about what was
special. New name makes the role obvious at every call site.

Adds `WritebackFile::create(path)` and `WritebackFile::open(path)`
constructors so callers don't have to assemble a `File` first.

No alias kept; this is a clean 0.18 rename. See
freemkv-private/memory/0_18_redesign.md.

Single contributor: MattJackson.
This commit is contained in:
matthew
2026-05-09 08:53:17 -07:00
parent 40fd44e63a
commit d42c7d17be
6 changed files with 141 additions and 115 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/disc/mod.rs
+9 -11
View File
@@ -1418,10 +1418,11 @@ impl Disc {
f
};
// Wrap the raw `File` in our bounded-cache writer (drains
// dirty pages continuously instead of bursting; see
// `crate::io`). The Writer moves into the consumer thread.
let file = crate::io::Writer::new(file).map_err(|e| Error::IoError { source: e })?;
// Wrap the raw `File` in our bounded-cache `WritebackFile`
// (drains dirty pages continuously instead of bursting; see
// `crate::io`). The `WritebackFile` moves into the consumer
// thread.
let file = crate::io::WritebackFile::new(file).map_err(|e| Error::IoError { source: e })?;
let batch: u16 = match opts.batch_sectors {
Some(b) => b,
None if opts.skip_on_error => ecc_sectors(self.format),
@@ -1435,7 +1436,7 @@ impl Disc {
// sweep finishes are the patch pass's job.
let regions: Vec<(u64, u64)> = map.ranges_with(&[mapfile::SectorStatus::NonTried]);
// Spawn the consumer. It owns Writer + Mapfile; the producer
// Spawn the consumer. It owns WritebackFile + Mapfile; the producer
// (this thread) keeps `reader`, `read_ctx`, halt + set_speed.
let (work_tx, prog_rx, consumer_handle) = spawn_consumer(ConsumerInputs {
file,
@@ -1978,14 +1979,11 @@ impl Disc {
let is_regular = std::fs::metadata(path)
.map(|m| m.file_type().is_file())
.unwrap_or(false);
let file = std::fs::OpenOptions::new()
.write(true)
.open(path)
.map_err(|e| Error::IoError { source: e })?;
// Same bounded-cache writeback wrapper sweep uses, so patch's
// Same bounded-cache `WritebackFile` sweep uses, so patch's
// recovery writes (sparse but can be many across a damaged region)
// get the burst-flush protection on slow / NFS-backed staging.
let mut file = crate::io::Writer::new(file).map_err(|e| Error::IoError { source: e })?;
let mut file =
crate::io::WritebackFile::open(path).map_err(|e| Error::IoError { source: e })?;
// Log ISO file size at patch start for write monitoring
if let Ok(metadata) = std::fs::metadata(path) {
src/disc/sweep_pipeline.rs
+3 -3
View File
@@ -9,7 +9,7 @@
//! both costs.
//!
//! This module decouples them. A consumer thread owns the
//! [`crate::io::Writer`] (the ISO file) and the
//! [`crate::io::WritebackFile`] (the ISO file) and the
//! [`super::mapfile::Mapfile`]. The producer thread (the caller of
//! `Disc::sweep`) keeps the [`crate::sector::SectorReader`], the
//! [`super::read_error`] state machine, and decrypt — so what enters
@@ -112,7 +112,7 @@ pub(super) struct ConsumerSummary {
/// happens on the producer side before send, so the consumer never
/// sees keys.
pub(super) struct ConsumerInputs {
pub file: crate::io::Writer,
pub file: crate::io::WritebackFile,
pub map: Mapfile,
/// `sync_all`-on-failure-is-an-error iff the output is a regular
/// file. `/dev/null` and pipes always fail `sync_all`; that's not
@@ -279,7 +279,7 @@ fn apply_item(
.file
.seek(SeekFrom::Start(pos))
.map_err(|e| Error::IoError { source: e })?;
// Subsequent writes are sequential; `crate::io::Writer`'s
// Subsequent writes are sequential; `crate::io::WritebackFile`'s
// seek-elision keeps them on the writeback pipeline path.
let mut filled = 0u64;
while filled < len {
src/io/mod.rs
+11 -11
View File
@@ -1,16 +1,16 @@
//! File I/O helpers that bound kernel cache pressure on big writes.
//!
//! `Writer` is a drop-in wrapper around `std::fs::File` for any call
//! site that performs large sequential writes (sweep, mux, etc.). It
//! implements `Write` and `Seek` so existing code paths can swap
//! `File` for `Writer` with no body changes. Internally it drives a
//! `WritebackPipeline` that, on Linux, drains dirty pages continuously
//! at 32 MB granularity to avoid the kernel's accumulate-then-burst
//! flush behaviour. macOS and Windows use a no-op pipeline — their
//! default cache policies have not been shown to exhibit the same
//! pathology for this access pattern.
//! `WritebackFile` is a drop-in wrapper around `std::fs::File` for any
//! call site that performs large sequential writes (sweep, patch, mux,
//! etc.). It implements `Write` and `Seek` so existing code paths can
//! swap `File` for `WritebackFile` with no body changes. Internally it
//! drives a `WritebackPipeline` that, on Linux, drains dirty pages
//! continuously at 32 MB granularity to avoid the kernel's
//! accumulate-then-burst flush behaviour. macOS and Windows use a
//! no-op pipeline — their default cache policies have not been shown
//! to exhibit the same pathology for this access pattern.
mod writeback;
mod writer;
mod writeback_file;
pub(crate) use writer::Writer;
pub(crate) use writeback_file::WritebackFile;
src/io/writeback_file.rs
+112
View File
@@ -0,0 +1,112 @@
//! `WritebackFile` — a `File` wrapper whose reason for existing is the
//! bounded-cache writeback pipeline.
//!
//! Why: large sequential writes (sweep, patch, mux on UHD-scale output)
//! left to the kernel's default writeback policy accumulate hundreds of
//! megabytes of dirty pages and then burst-flush, stalling subsequent
//! writes for seconds at a time. `WritebackFile` drives a continuous
//! [`super::writeback::WritebackPipeline`] that on Linux issues
//! incremental `sync_file_range` + `posix_fadvise(DONTNEED)` calls at
//! 32 MB granularity so dirty pages drain at the same rate they're
//! produced. macOS and Windows fall through to a no-op pipeline — their
//! default cache policies have not been shown to exhibit the same
//! pathology for this access pattern.
//!
//! It implements `Write` and `Seek` so any call site that wrote to a
//! plain `File` through those traits (sweep, patch, mux) can swap in
//! `WritebackFile` without touching the body of the loop. The wrapper
//! also tracks the current file position to feed the pipeline with
//! progress + seek boundaries.
//!
//! See `super::writeback::linux` for the underlying pathology and the
//! strategy.
use std::fs::{File, OpenOptions};
use std::io::{self, Seek, SeekFrom, Write};
use std::path::Path;
use super::writeback::WritebackPipeline;
const CHUNK_BYTES: u64 = 32 * 1024 * 1024;
pub(crate) struct WritebackFile {
file: File,
pipeline: WritebackPipeline,
pos: u64,
}
impl WritebackFile {
/// Wrap an open `File`. The current OS file position is queried
/// once so the pipeline starts tracking from wherever the file
/// already is (typically 0 for fresh files; non-zero for resumed
/// or appended files).
pub(crate) fn new(mut file: File) -> io::Result<Self> {
let pos = file.stream_position()?;
let pipeline = WritebackPipeline::new(&file, pos, CHUNK_BYTES);
Ok(Self {
file,
pipeline,
pos,
})
}
/// Create a new file at `path` (truncating any existing contents)
/// and wrap it. Convenience for the common
/// `File::create(path)` + `WritebackFile::new(file)` pair so callers
/// don't have to assemble a `File` first.
pub(crate) fn create(path: &Path) -> io::Result<Self> {
let file = File::create(path)?;
Self::new(file)
}
/// Open an existing file at `path` for writing (no truncation) and
/// wrap it. Mirrors `File::open` semantics for the writable case
/// — used by patch / resume paths that mutate an existing ISO in
/// place.
pub(crate) fn open(path: &Path) -> io::Result<Self> {
let file = OpenOptions::new().write(true).open(path)?;
Self::new(file)
}
/// Drain in-flight writeback then issue a full fsync. Use this in
/// place of `File::sync_all`.
pub(crate) fn sync_all(&mut self) -> io::Result<()> {
self.pipeline.finalize();
self.file.sync_all()
}
}
impl Write for WritebackFile {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
let n = self.file.write(buf)?;
self.pos += n as u64;
self.pipeline.note_progress(self.pos);
Ok(n)
}
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
self.file.write_all(buf)?;
self.pos += buf.len() as u64;
self.pipeline.note_progress(self.pos);
Ok(())
}
fn flush(&mut self) -> io::Result<()> {
self.file.flush()
}
}
impl Seek for WritebackFile {
fn seek(&mut self, from: SeekFrom) -> io::Result<u64> {
let p = self.file.seek(from)?;
// Only treat seeks that actually move the position as
// boundaries — sweep does a redundant `seek(Current(pos))`
// before every write, and we don't want that to drain the
// pipeline on every iteration.
if p != self.pos {
self.pipeline.handle_seek(p);
self.pos = p;
}
Ok(p)
}
}
src/io/writer.rs
-84
View File
@@ -1,84 +0,0 @@
//! `Writer` — a drop-in `File` wrapper that keeps the kernel page
//! cache bounded during large sequential output.
//!
//! Implements `Write` and `Seek`, so any call site that uses `File`
//! through those traits (sweep, mux, patch) can swap to `Writer`
//! without touching the body of the loop. The wrapper tracks the
//! current file position and forwards each write to a
//! [`super::writeback::WritebackPipeline`], which on Linux schedules
//! incremental `sync_file_range` + `posix_fadvise(DONTNEED)` calls
//! to drain dirty pages continuously instead of letting the kernel
//! burst-flush hundreds of MB at a time.
//!
//! See `super::writeback::linux` for the pathology and the strategy.
use std::fs::File;
use std::io::{self, Seek, SeekFrom, Write};
use super::writeback::WritebackPipeline;
const CHUNK_BYTES: u64 = 32 * 1024 * 1024;
pub(crate) struct Writer {
file: File,
pipeline: WritebackPipeline,
pos: u64,
}
impl Writer {
/// Wrap an open `File`. The current OS file position is queried
/// once so the pipeline starts tracking from wherever the file
/// already is (typically 0 for fresh files; non-zero for resumed
/// or appended files).
pub(crate) fn new(mut file: File) -> io::Result<Self> {
let pos = file.stream_position()?;
let pipeline = WritebackPipeline::new(&file, pos, CHUNK_BYTES);
Ok(Self {
file,
pipeline,
pos,
})
}
/// Drain in-flight writeback then issue a full fsync. Use this in
/// place of `File::sync_all`.
pub(crate) fn sync_all(&mut self) -> io::Result<()> {
self.pipeline.finalize();
self.file.sync_all()
}
}
impl Write for Writer {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
let n = self.file.write(buf)?;
self.pos += n as u64;
self.pipeline.note_progress(self.pos);
Ok(n)
}
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
self.file.write_all(buf)?;
self.pos += buf.len() as u64;
self.pipeline.note_progress(self.pos);
Ok(())
}
fn flush(&mut self) -> io::Result<()> {
self.file.flush()
}
}
impl Seek for Writer {
fn seek(&mut self, from: SeekFrom) -> io::Result<u64> {
let p = self.file.seek(from)?;
// Only treat seeks that actually move the position as
// boundaries — sweep does a redundant `seek(Current(pos))`
// before every write, and we don't want that to drain the
// pipeline on every iteration.
if p != self.pos {
self.pipeline.handle_seek(p);
self.pos = p;
}
Ok(p)
}
}
src/mux/resolve.rs
+6 -6
View File
@@ -242,23 +242,23 @@ pub fn output(
match parsed {
StreamUrl::Mkv { ref path } => {
validate_file_path(path, "mkv")?;
// Wrap the raw `File` in `crate::io::Writer` (bounded-cache
// Wrap the output in `crate::io::WritebackFile` (bounded-cache
// writeback) so a UHD-scale MKV mux to slow / network-attached
// staging doesn't hit the dirty-page burst pathology that
// sweep already side-steps. BufWriter sits on top to coalesce
// mux's many small EBML element writes.
let file = std::fs::File::create(path)?;
let writer: Box<dyn super::WriteSeek> = Box::new(std::io::BufWriter::with_capacity(
IO_BUF_SIZE,
crate::io::Writer::new(file)?,
crate::io::WritebackFile::create(path)?,
));
Ok(Box::new(MkvStream::create(writer, title)?))
}
StreamUrl::M2ts { ref path } => {
validate_file_path(path, "m2ts")?;
let file = std::fs::File::create(path)?;
let writer =
std::io::BufWriter::with_capacity(IO_BUF_SIZE, crate::io::Writer::new(file)?);
let writer = std::io::BufWriter::with_capacity(
IO_BUF_SIZE,
crate::io::WritebackFile::create(path)?,
);
Ok(Box::new(M2tsStream::create(writer, title)?))
}
StreamUrl::Network { ref addr } => {