fix: zip read sizing

__test__/utils.spec.mjs

@@ -57,7 +57,7 @@ test("read file", async (t) => {
 
   const dropletHandler = new DropletHandler();
 
-  const stream = dropletHandler.readFile(dirName, "TESTFILE");
+  const stream = dropletHandler.readFile(dirName, "TESTFILE", BigInt(0), BigInt(testString.length));
 
   let finalString = "";
 
@@ -154,11 +154,34 @@ test.skip("zip manifest test", async (t) => {
     )
   );
 
-  const file = manifest[Object.keys(manifest).at(0)];
-  const amount = file.ids.length;
+  for (const [filename, data] of Object.entries(manifest)) {
+    let start = 0;
+    for (const [chunkIndex, length] of data.lengths.entries()) {
+      const stream = (
+        await dropletHandler.readFile(
+          "./assets/TheGame.zip",
+          filename,
+          BigInt(start),
+          BigInt(start + length)
+        )
+      ).getStream();
 
-  if(amount > 20) {
-    return t.fail(`Zip manifest has ${amount} chunks, more than 20`);
+      let streamLength = 0;
+      await stream.pipeTo(
+        new WritableStream({
+          write(chunk) {
+            streamLength += chunk.length;
+          },
+        })
+      );
+
+      if (streamLength != length)
+        return t.fail(
+          `stream length for chunk index ${chunkIndex} was not expected: real: ${streamLength} vs expected: ${length}`
+        );
+
+      start += length;
+    }
   }
 
   t.pass();

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@drop-oss/droplet",
-  "version": "2.1.1",
+  "version": "2.2.0",
   "main": "index.js",
   "types": "index.d.ts",
   "napi": {

src/manifest.rs

@@ -1,9 +1,4 @@
-use std::{
-  collections::HashMap,
-  io::{BufRead, BufReader},
-  sync::Arc,
-  thread,
-};
+use std::{collections::HashMap, sync::Arc, thread};
 
 use napi::{
   threadsafe_function::{ThreadsafeFunction, ThreadsafeFunctionCallMode},
@@ -46,6 +41,14 @@ pub fn generate_manifest<'a>(
     .ok_or(napi::Error::from_reason(
     "Could not create backend for path.",
   ))?;
+
+  // This is unsafe (obviously)
+  // But it's allg as long the DropletHandler doesn't get
+  // dropped while we're generating the manifest.
+  let backend: &'static mut Box<dyn VersionBackend + Send> =
+    unsafe { std::mem::transmute(backend) };
+
+  thread::spawn(move || {
     let files = backend.list_files();
 
     // Filepath to chunk data
@@ -54,9 +57,10 @@ pub fn generate_manifest<'a>(
     let total: i32 = files.len() as i32;
     let mut i: i32 = 0;
 
+    let mut buf = [0u8; 1024 * 16];
+
     for version_file in files {
-      let reader = backend.reader(&version_file).unwrap();
-      let mut reader = BufReader::with_capacity(8128, reader);
+      let mut reader = backend.reader(&version_file, 0, 0).unwrap();
 
       let mut chunk_data = ChunkData {
         permissions: version_file.permission,
@@ -72,25 +76,25 @@ pub fn generate_manifest<'a>(
         let mut file_empty = false;
 
         loop {
-          let read_buf = reader.fill_buf().unwrap();
-          let buf_length = read_buf.len();
+          let read = reader.read(&mut buf).unwrap();
 
-          length += buf_length;
+          length += read;
 
           if length >= CHUNK_SIZE {
             break;
           }
 
           // If we're out of data, add this chunk and then move onto the next file
-          if buf_length == 0 {
+          if read == 0 {
             file_empty = true;
             break;
           }
 
-          buffer.extend_from_slice(read_buf);
-          reader.consume(length);
+          buffer.extend_from_slice(&buf[..read]);
         }
 
+        println!("created chunk of size {}", length);
+
         let chunk_id = Uuid::new_v4();
         let checksum = md5::compute(buffer).0;
         let checksum_string = hex::encode(checksum);
@@ -124,6 +128,7 @@ pub fn generate_manifest<'a>(
       Ok(json!(chunks).to_string()),
       ThreadsafeFunctionCallMode::Blocking,
     );
+  });
 
   Ok(())
 }

src/version/backends.rs

@@ -2,7 +2,7 @@
 use std::os::unix::fs::PermissionsExt;
 use std::{
   fs::{self, metadata, File},
-  io::{self, Read, Sink},
+  io::{self, Read, Seek, SeekFrom, Sink},
   path::{Path, PathBuf},
   sync::Arc,
 };
@@ -12,7 +12,7 @@ use rawzip::{
   FileReader, ZipArchive, ZipArchiveEntryWayfinder, ZipEntry, ZipReader, RECOMMENDED_BUFFER_SIZE,
 };
 
-use crate::version::types::{MinimumFileObject, Skippable, VersionBackend, VersionFile};
+use crate::version::types::{MinimumFileObject, VersionBackend, VersionFile};
 
 pub fn _list_files(vec: &mut Vec<PathBuf>, path: &Path) {
   if metadata(path).unwrap().is_dir() {
@@ -52,8 +52,21 @@ impl VersionBackend for PathVersionBackend {
     results
   }
 
-  fn reader(&mut self, file: &VersionFile) -> Option<Box<dyn MinimumFileObject + 'static>> {
-    let file = File::open(self.base_dir.join(file.relative_filename.clone())).ok()?;
+  fn reader(
+    &mut self,
+    file: &VersionFile,
+    start: u64,
+    end: u64,
+  ) -> Option<Box<dyn MinimumFileObject + 'static>> {
+    let mut file = File::open(self.base_dir.join(file.relative_filename.clone())).ok()?;
+
+    if start != 0 {
+      file.seek(SeekFrom::Start(start)).ok()?;
+    }
+
+    if end != 0 {
+      return Some(Box::new(file.take(end - start)));
+    }
 
     return Some(Box::new(file));
   }
@@ -103,28 +116,53 @@ impl ZipVersionBackend {
   pub fn new_entry<'archive>(
     &self,
     entry: ZipEntry<'archive, FileReader>,
+    start: u64,
+    end: u64,
   ) -> ZipFileWrapper<'archive> {
-    let deflater = DeflateDecoder::new(entry.reader());
-    ZipFileWrapper { reader: deflater }
+    let mut deflater = DeflateDecoder::new(entry.reader());
+    if start != 0 {
+      io::copy(&mut (&mut deflater).take(start), &mut Sink::default()).unwrap();
+    }
+    ZipFileWrapper {
+      reader: deflater,
+      limit: (end - start) as usize,
+      current: 0,
+    }
   }
 }
 
 pub struct ZipFileWrapper<'archive> {
   reader: DeflateDecoder<ZipReader<'archive, FileReader>>,
+  limit: usize,
+  current: usize,
 }
 
+/**
+ * This read implemention is a result of debugging hell
+ * It should probably be replaced with a .take() call.
+ */
 impl<'a> Read for ZipFileWrapper<'a> {
   fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
+    let has_limit = self.limit != 0;
+
+    // End this stream if the read is the right size
+    if has_limit {
+      if self.current >= self.limit {
+        return Ok(0);
+      }
+    }
+
     let read = self.reader.read(buf)?;
-    Ok(read)
+    if self.limit != 0 {
+      self.current += read;
+      if self.current > self.limit {
+        let over = self.current - self.limit;
+        return Ok(read - over);
+      }
+    }
+    return Ok(read);
   }
 }
-impl<'a> Skippable for ZipFileWrapper<'a> {
-  fn skip(&mut self, amount: u64) {
-    io::copy(&mut self.take(amount), &mut Sink::default()).unwrap();
-  }
-}
-impl<'a> MinimumFileObject for ZipFileWrapper<'a> {}
 
 impl ZipVersionBackend {
   fn find_wayfinder(&mut self, filename: &str) -> Option<ZipArchiveEntryWayfinder> {
@@ -163,11 +201,16 @@ impl VersionBackend for ZipVersionBackend {
     results
   }
 
-  fn reader(&mut self, file: &VersionFile) -> Option<Box<dyn MinimumFileObject + '_>> {
+  fn reader(
+    &mut self,
+    file: &VersionFile,
+    start: u64,
+    end: u64,
+  ) -> Option<Box<dyn MinimumFileObject + '_>> {
     let wayfinder = self.find_wayfinder(&file.relative_filename)?;
     let local_entry = self.archive.get_entry(wayfinder).unwrap();
 
-    let wrapper = self.new_entry(local_entry);
+    let wrapper = self.new_entry(local_entry, start, end);
 
     Some(Box::new(wrapper))
   }

src/version/types.rs

@@ -1,6 +1,5 @@
 use std::{
-  fmt::Debug,
-  io::{Read, Seek, SeekFrom},
+  fmt::Debug, io::Read
 };
 
 use dyn_clone::DynClone;
@@ -13,36 +12,26 @@ pub struct VersionFile {
   pub size: u64,
 }
 
-pub trait Skippable {
-  fn skip(&mut self, amount: u64);
-}
-impl<T> Skippable for T
-where
-  T: Seek,
-{
-  fn skip(&mut self, amount: u64) {
-    self.seek(SeekFrom::Start(amount)).unwrap();
-  }
-}
-
-pub trait MinimumFileObject: Read + Send + Skippable {}
-impl<T: Read + Send + Seek> MinimumFileObject for T {}
+pub trait MinimumFileObject: Read + Send  {}
+impl<T: Read + Send> MinimumFileObject for T {}
 
 // Intentionally not a generic, because of types in read_file
 pub struct ReadToAsyncRead<'a> {
   pub inner: Box<dyn Read + Send + 'a>,
 }
 
+const ASYNC_READ_BUFFER_SIZE: usize = 8128;
+
 impl<'a> AsyncRead for ReadToAsyncRead<'a> {
   fn poll_read(
     mut self: std::pin::Pin<&mut Self>,
     _cx: &mut std::task::Context<'_>,
     buf: &mut tokio::io::ReadBuf<'_>,
   ) -> std::task::Poll<io::Result<()>> {
-    let mut read_buf = [0u8; 8192];
-    let var_name = self.inner.read(&mut read_buf).unwrap();
-    let amount = var_name.min(buf.remaining());
-    buf.put_slice(&read_buf[0..amount]);
+    let mut read_buf = [0u8; ASYNC_READ_BUFFER_SIZE];
+    let read_size = ASYNC_READ_BUFFER_SIZE.min(buf.remaining());
+    let read = self.inner.read(&mut read_buf[0..read_size]).unwrap();
+    buf.put_slice(&read_buf[0..read]);
     std::task::Poll::Ready(Ok(()))
   }
 }
@@ -50,7 +39,7 @@ impl<'a> AsyncRead for ReadToAsyncRead<'a> {
 pub trait VersionBackend: DynClone {
   fn list_files(&mut self) -> Vec<VersionFile>;
   fn peek_file(&mut self, sub_path: String) -> Option<VersionFile>;
-  fn reader(&mut self, file: &VersionFile) -> Option<Box<dyn MinimumFileObject + '_>>;
+  fn reader(&mut self, file: &VersionFile, start: u64, end: u64) -> Option<Box<dyn MinimumFileObject + '_>>;
 }
 
 dyn_clone::clone_trait_object!(VersionBackend);

src/version/utils.rs

@@ -1,4 +1,6 @@
-use std::{collections::HashMap, fs::File, io::Read, path::Path};
+use std::{
+  collections::HashMap, fs::File, path::Path
+};
 
 use napi::{bindgen_prelude::*, sys::napi_value__, tokio_stream::StreamExt};
 use tokio_util::codec::{BytesCodec, FramedRead};
@@ -115,20 +117,16 @@ impl<'a> DropletHandler<'a> {
         size: 0,       // Shouldn't matter
       };
       // Use `?` operator for cleaner error propagation from `Option`
-      let mut reader = backend.reader(&version_file).ok_or(napi::Error::from_reason("Failed to create reader."))?;
+      let reader = backend
+        .reader(
+          &version_file,
+          start.map(|e| e.get_u64().1).unwrap_or(0),
+          end.map(|e| e.get_u64().1).unwrap_or(0),
+        )
+        .ok_or(napi::Error::from_reason("Failed to create reader."))?;
 
-      if let Some(skip) = start.clone() {
-        reader.skip(skip.get_u64().1.into());
-        // io::copy(&mut reader.by_ref().take(skip.into()), &mut io::sink()).unwrap();
-      }
-
-      let async_reader = if let Some(limit) = end {
-        let amount = limit.get_u64().1 - start.map_or(Some(0), |v| Some(v.get_u64().1)).unwrap();
-        ReadToAsyncRead {
-          inner: Box::new(reader.take(amount.into())),
-        }
-      } else {
-        ReadToAsyncRead { inner: reader }
+      let async_reader = ReadToAsyncRead {
+        inner: reader,
       };
 
       // Create a FramedRead stream with BytesCodec for chunking
@@ -147,9 +145,7 @@ impl<'a> DropletHandler<'a> {
       Ok(ReadableStream::create_with_stream_bytes(&env, stream).unwrap())
     })?;
 
-    Ok(JsDropStreamable {
-      inner: stream,
-    })
+    Ok(JsDropStreamable { inner: stream })
   }
 }
 
@@ -164,4 +160,4 @@ impl JsDropStreamable {
   pub fn get_stream(&self) -> *mut napi_value__ {
     self.inner.raw()
   }
-}
+}