Cleanup to allow use of most functions when linking the library, including mounting and creating filesystems

src/disk/cache/mod.rs

@@ -0,0 +1,96 @@
+use std::{cmp, ptr};
+use syscall::error::Result;
+
+use disk::Disk;
+
+use self::lru_cache::LruCache;
+
+mod linked_hash_map;
+mod lru_cache;
+
+fn copy_memory(src: &[u8], dest: &mut [u8]) -> usize {
+    let len = cmp::min(src.len(), dest.len());
+    unsafe { ptr::copy(src.as_ptr(), dest.as_mut_ptr(), len) };
+    len
+}
+
+pub struct DiskCache<T> {
+    inner: T,
+    cache: LruCache<u64, [u8; 512]>,
+}
+
+impl<T: Disk> DiskCache<T> {
+    pub fn new(inner: T) -> Self {
+        DiskCache {
+            inner: inner,
+            cache: LruCache::new(65536) // 32 MB cache
+        }
+    }
+}
+
+impl<T: Disk> Disk for DiskCache<T> {
+    fn read_at(&mut self, block: u64, buffer: &mut [u8]) -> Result<usize> {
+        // println!("Cache read at {}", block);
+
+        let mut read = 0;
+        let mut failed = false;
+        for i in 0..(buffer.len() + 511)/512 {
+            let block_i = block + i as u64;
+
+            let buffer_i = i * 512;
+            let buffer_j = cmp::min(buffer_i + 512, buffer.len());
+            let buffer_slice = &mut buffer[buffer_i .. buffer_j];
+
+            if let Some(cache_buf) = self.cache.get_mut(&block_i) {
+                read += copy_memory(cache_buf, buffer_slice);
+            }else{
+                failed = true;
+                break;
+            }
+        }
+
+        if failed {
+            self.inner.read_at(block, buffer)?;
+
+            read = 0;
+            for i in 0..(buffer.len() + 511)/512 {
+                let block_i = block + i as u64;
+
+                let buffer_i = i * 512;
+                let buffer_j = cmp::min(buffer_i + 512, buffer.len());
+                let buffer_slice = &buffer[buffer_i .. buffer_j];
+
+                let mut cache_buf = [0; 512];
+                read += copy_memory(buffer_slice, &mut cache_buf);
+                self.cache.insert(block_i, cache_buf);
+            }
+        }
+
+        Ok(read)
+    }
+
+    fn write_at(&mut self, block: u64, buffer: &[u8]) -> Result<usize> {
+        // println!("Cache write at {}", block);
+
+        self.inner.write_at(block, buffer)?;
+
+        let mut written = 0;
+        for i in 0..(buffer.len() + 511)/512 {
+            let block_i = block + i as u64;
+
+            let buffer_i = i * 512;
+            let buffer_j = cmp::min(buffer_i + 512, buffer.len());
+            let buffer_slice = &buffer[buffer_i .. buffer_j];
+
+            let mut cache_buf = [0; 512];
+            written += copy_memory(buffer_slice, &mut cache_buf);
+            self.cache.insert(block_i, cache_buf);
+        }
+
+        Ok(written)
+    }
+
+    fn size(&mut self) -> Result<u64> {
+        self.inner.size()
+    }
+}