job skel

src/job.rs

@@ -1,7 +1,39 @@
 use super::*;
 use std::fs::{
-    File, Metadata,    
+    File, Metadata, OpenOptions,   
 };
+use std::convert::TryFrom;
+use std::path::Path;
+use std::io::{
+    self,
+    Read,
+};
+
+#[derive(Debug)]
+pub struct Prelude
+{
+    file: File,
+    stat: Metadata,
+    offset: usize,
+}
+
+impl Prelude{
+    pub fn len(&self) -> usize
+    {
+	usize::try_from(self.stat.len()).expect("Failed to fit file size into pointer size")
+    }
+
+    /// Convert this job prelude into a job, assigning it this state
+    pub fn start(self, state: state::State) -> Job
+    {
+	Job {
+	    fd: self.file,
+	    stat: self.stat,
+	    offset: self.offset,
+	    state,
+	}
+    }
+}
 
 #[derive(Debug)]
 pub struct Job
@@ -16,3 +48,68 @@ pub struct Job
 }
 
 //TODO: job's work :^)
+
+impl Job
+{
+    pub fn state(&self) -> &state::State
+    {
+	&self.state
+    }
+
+    pub fn info(&self) -> (&File, &Metadata)
+    {
+	(&self.fd, &self.stat)
+    }
+    
+    pub fn len(&self) -> usize
+    {
+	usize::try_from(self.stat.len()).expect("Failed to fit file size into pointer size")
+    }
+    
+    pub fn start(&self) -> usize
+    {
+	self.offset
+    }
+    pub fn end(&self) -> usize
+    {
+	self.len() + self.offset
+    }
+
+    /// Get the output slice for this job.
+    pub fn output_slice<'a, 'b>(&'a mut self) -> &'b mut [u8]
+	where 'a: 'b
+    {
+	unsafe {
+	    self.state.slice(self.start() .. self.end())
+	}
+    }
+}
+
+impl Read for Job
+{
+    #[inline] fn read(&mut self, buf: &mut [u8]) -> io::Result<usize>
+    {
+	self.fd.read(buf)
+    }
+}
+
+/// Create a job description for this file.
+///
+/// `sz` is the offset of the *end* of the last job. (or 0 for the first).
+/// `sz` is then updated with this file's size for this method to be used again on the next file.
+pub fn create_from_file(file: impl AsRef<Path>, sz: &mut usize) -> io::Result<Prelude>
+{
+    let file = OpenOptions::new()
+	.read(true)
+	.open(file.as_ref())?;
+    
+    let stat = file.metadata()?;
+    let offset = *sz;
+    
+    let prelude = Prelude {
+	file, stat, offset,
+    };
+    *sz += prelude.len();
+
+    Ok(prelude)
+}

src/main.rs

@@ -1,10 +1,10 @@
-
 #![allow(dead_code)]
 
 mod state;
 mod pool;
 mod map;
 mod job;
+mod work;
 
 fn main() {
     println!("Hello, world!");

src/pool.rs

@@ -12,9 +12,9 @@ use std::iter::FromIterator;
 
 fn work(recv: state::PendingReceiver<Job>) -> Result<(), Box<dyn std::error::Error>>
 {
-    while let Some(job) = recv.recv()?
+    while let Some(mut job) = recv.recv()?
     {
-	//todo: work on job
+	work::work_on(&mut job)?;
     }
 
     Ok(())

src/work.rs

@@ -0,0 +1,13 @@
+use super::*;
+use job::Job;
+use std::io::Read;
+
+pub fn work_on(job: &mut Job) -> Result<(), Box<dyn std::error::Error>>
+{
+    let output = job.output_slice();
+    let mut buf = [0u8; 4096];
+    while let Ok(read) = job.read(&mut buf) {
+	//TODO: copy from `job`'s file into `output`.
+    }
+    todo!()
+}