From d17b55089a78f0d7d5e2a926dc36ee8068785b5f Mon Sep 17 00:00:00 2001
From: Jeremy Soller <jackpot51@gmail.com>
Date: Mon, 16 May 2016 09:49:05 -0600
Subject: [PATCH] More efficient reads
---
src/filesystem.rs | 46 ++++++++++++++++++++++++++++++++++++++++------
1 file changed, 40 insertions(+), 6 deletions(-)
diff --git a/src/filesystem.rs b/src/filesystem.rs
index dd948c8..bbb3e21 100644
--- a/src/filesystem.rs
+++ b/src/filesystem.rs
@@ -1,3 +1,5 @@
+use std::cmp::min;
+
use system::error::{Result, Error, EEXIST, EISDIR, ENOENT, ENOSPC, ENOTDIR, ENOTEMPTY};
use super::{Disk, ExNode, Extent, Header, Node};
@@ -398,19 +400,51 @@ impl FileSystem {
let mut i = 0;
for extent in extents.iter() {
- for (block, size) in extent.blocks() {
+ let mut block = extent.block;
+ let mut length = extent.length;
+
+ if byte_offset > 0 && length > 0 {
let mut sector = [0; 512];
try!(self.read_at(block, &mut sector));
- if byte_offset < size && i < buf.len() {
- for (s_b, mut b) in sector[byte_offset..size].iter().zip(buf[i..].iter_mut()) {
- *b = *s_b;
- i += 1;
- }
+ let sector_size = min(sector.len() as u64, length) as usize;
+ for (s_b, mut b) in sector[byte_offset..sector_size].iter().zip(buf[i..].iter_mut()) {
+ *b = *s_b;
+ i += 1;
}
+ block += 1;
+ length -= sector_size as u64;
+
byte_offset = 0;
}
+
+ let length_aligned = ((min(length, (buf.len() - i) as u64)/512) * 512) as usize;
+
+ if length_aligned > 0 {
+ let extent_buf = &mut buf[i..i + length_aligned];
+ try!(self.read_at(block, extent_buf));
+ i += length_aligned;
+ block += (length_aligned as u64)/512;
+ length -= length_aligned as u64;
+ }
+
+ if length > 0 {
+ let mut sector = [0; 512];
+ try!(self.read_at(block, &mut sector));
+
+ let sector_size = min(sector.len() as u64, length) as usize;
+ for (s_b, mut b) in sector[..sector_size].iter().zip(buf[i..].iter_mut()) {
+ *b = *s_b;
+ i += 1;
+ }
+
+ block += 1;
+ length -= sector_size as u64;
+ }
+
+ assert_eq!(length, 0);
+ assert_eq!(block, extent.block + (extent.length + 511)/512);
}
Ok(i)
--
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