[thin_shrink] write test harness

tests/thin_shrink.rs

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+use anyhow::Result;
+use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
+use rand::Rng;
+use std::fs::OpenOptions;
+use std::io::{Cursor, Read, Seek, SeekFrom, Write};
+
+use thinp::file_utils;
+use thinp::thin::xml::{self, Visit};
+
+//------------------------------------
+
+struct ThinBlock {
+    thin_id: u32,
+    thin_block: u64,
+    data_block: u64,
+    block_size: usize,
+}
+
+struct ThinReadRef {
+    pub data: Vec<u8>,
+}
+
+struct ThinWriteRef<'a, W: Write + Seek> {
+    file: &'a mut W,
+    pub data: Vec<u8>,
+}
+
+impl ThinBlock {
+    fn read_ref<R: Read + Seek>(&self, r: &mut R) -> Result<ThinReadRef> {
+        let mut rr = ThinReadRef {
+            data: vec![0; self.block_size],
+        };
+        r.seek(SeekFrom::Start(self.data_block * (self.block_size as u64)))?;
+        r.read_exact(&mut rr.data[0..])?;
+        Ok(rr)
+    }
+
+    fn zero_ref<'a, W: Write + Seek>(&self, w: &'a mut W) -> ThinWriteRef<'a, W> {
+        ThinWriteRef {
+            file: w,
+            data: vec![0; self.block_size],
+        }
+    }
+
+    fn write_ref<'a, W>(&self, w: &'a mut W) -> Result<ThinWriteRef<'a, W>>
+    where
+        W: Read + Write + Seek,
+    {
+        let mut data = vec![0; self.block_size];
+        w.seek(SeekFrom::Start(self.data_block * (self.block_size as u64)))?;
+        w.read_exact(&mut data[0..])?;
+
+        let wr = ThinWriteRef {
+            file: w,
+            data: vec![0; self.block_size],
+        };
+
+        Ok(wr)
+    }
+}
+
+impl<'a, W: Write + Seek> Drop for ThinWriteRef<'a, W> {
+    fn drop(&mut self) {
+        self.file.write_all(&self.data[0..]).unwrap();
+    }
+}
+
+//------------------------------------
+
+trait ThinVisitor {
+    fn thin_block(&mut self, tb: &ThinBlock) -> Result<()>;
+}
+
+struct ThinXmlVisitor<'a, V: ThinVisitor> {
+    inner: &'a mut V,
+    block_size: Option<u32>,
+    thin_id: Option<u32>,
+}
+
+impl<'a, V: ThinVisitor> xml::MetadataVisitor for ThinXmlVisitor<'a, V> {
+    fn superblock_b(&mut self, sb: &xml::Superblock) -> Result<Visit> {
+        self.block_size = Some(sb.data_block_size);
+        Ok(Visit::Continue)
+    }
+
+    fn superblock_e(&mut self) -> Result<Visit> {
+        Ok(Visit::Continue)
+    }
+
+    fn device_b(&mut self, d: &xml::Device) -> Result<Visit> {
+        self.thin_id = Some(d.dev_id);
+        Ok(Visit::Continue)
+    }
+
+    fn device_e(&mut self) -> Result<Visit> {
+        Ok(Visit::Continue)
+    }
+
+    fn map(&mut self, m: &xml::Map) -> Result<Visit> {
+        for i in 0..m.len {
+            let block = ThinBlock {
+                thin_id: self.thin_id.unwrap(),
+                thin_block: m.thin_begin + i,
+                data_block: m.data_begin + i,
+                block_size: self.block_size.unwrap() as usize,
+            };
+            self.inner.thin_block(&block)?;
+        }
+        Ok(Visit::Continue)
+    }
+
+    fn eof(&mut self) -> Result<Visit> {
+        Ok(Visit::Stop)
+    }
+}
+
+fn thin_visit<R, M>(input: R, visitor: &mut M) -> Result<()>
+where
+    R: Read,
+    M: ThinVisitor,
+{
+    let mut xml_visitor = ThinXmlVisitor {
+        inner: visitor,
+        block_size: None,
+        thin_id: None,
+    };
+
+    xml::read(input, &mut xml_visitor)
+}
+
+//------------------------------------
+
+// To test thin_shrink we'd like to stamp a known pattern across the
+// provisioned areas of the thins in the pool, do the shrink, verify
+// the patterns.
+
+// A simple linear congruence generator used to create the data to
+// go into the thin blocks.
+struct Generator {
+    x: u64,
+    a: u64,
+    c: u64,
+}
+
+impl Generator {
+    fn new() -> Generator {
+        Generator {
+            x: 0,
+            a: 6364136223846793005,
+            c: 1442695040888963407,
+        }
+    }
+
+    fn step(&mut self) {
+        self.x = (self.a * self.x) + self.c
+    }
+
+    fn fill_buffer(&mut self, seed: u64, bytes: &mut [u8]) {
+        self.x = seed;
+
+        assert!(bytes.len() % 8 == 64);
+        let nr_words = bytes.len() / 8;
+        let mut out = Cursor::new(bytes);
+
+        for _ in 0..nr_words {
+            out.write_u64::<LittleEndian>(self.x).unwrap();
+            self.step();
+        }
+    }
+
+    fn verify_buffer(&mut self, seed: u64, bytes: &[u8]) {
+        self.x = seed;
+
+        assert!(bytes.len() % 8 == 64);
+        let nr_words = bytes.len() / 8;
+        let mut input = Cursor::new(bytes);
+
+        for _ in 0..nr_words {
+            let w = input.read_u64::<LittleEndian>().unwrap();
+            assert_eq!(w, self.x);
+            self.step();
+        }
+    }
+}
+
+//------------------------------------
+
+struct Stamper<'a, W: Write + Seek> {
+    data_file: &'a mut W,
+    seed: u64,
+}
+
+impl<'a, W: Write + Seek> Stamper<'a, W> {
+    fn new(w: &'a mut W, seed: u64) -> Stamper<'a, W> {
+        Stamper { data_file: w, seed }
+    }
+}
+
+impl<'a, W: Write + Seek> ThinVisitor for Stamper<'a, W> {
+    fn thin_block(&mut self, b: &ThinBlock) -> Result<()> {
+        let mut wr = b.zero_ref(self.data_file);
+        let mut gen = Generator::new();
+        gen.fill_buffer(
+            self.seed ^ (b.thin_id as u64) ^ b.thin_block,
+            &mut wr.data[0..],
+        );
+        Ok(())
+    }
+}
+
+//------------------------------------
+
+struct Verifier<'a, R: Read + Seek> {
+    data_file: &'a mut R,
+    seed: u64,
+}
+
+impl<'a, R: Read + Seek> Verifier<'a, R> {
+    fn new(r: &'a mut R, seed: u64) -> Verifier<'a, R> {
+        Verifier { data_file: r, seed }
+    }
+}
+
+impl<'a, R: Read + Seek> ThinVisitor for Verifier<'a, R> {
+    fn thin_block(&mut self, b: &ThinBlock) -> Result<()> {
+        let rr = b.read_ref(self.data_file)?;
+        let mut gen = Generator::new();
+        gen.verify_buffer(self.seed ^ (b.thin_id as u64) ^ b.thin_block, &rr.data[0..]);
+        Ok(())
+    }
+}
+
+//------------------------------------
+
+fn create_data_file(xml_path: &str) -> Result<std::fs::File> {
+    let input = OpenOptions::new().read(true).write(false).open(xml_path)?;
+
+    let sb = xml::read_superblock(input)?;
+    let nr_blocks = sb.nr_data_blocks as u64;
+    let block_size = sb.data_block_size as u64 * 512;
+
+    let file = file_utils::temp_file_sized(nr_blocks * block_size)?;
+    Ok(file)
+}
+
+fn main(xml_path: &str) -> Result<()> {
+    let mut data_file = create_data_file(xml_path)?;
+    let mut xml_in = OpenOptions::new().read(true).write(false).open(xml_path)?;
+
+    let mut rng = rand::thread_rng();
+    let seed = rng.gen::<u64>();
+
+    let mut stamper = Stamper::new(&mut data_file, seed);
+    thin_visit(&mut xml_in, &mut stamper)?;
+
+    let mut verifier = Verifier::new(&mut data_file, seed);
+    thin_visit(&mut xml_in, &mut verifier)?;
+    Ok(())
+}