Move to storage folder

crates/librqbit/src/storage/example.rs

@@ -0,0 +1,97 @@
+use std::{collections::HashMap, path::Path};
+
+use anyhow::Context;
+use librqbit_core::lengths::{Lengths, ValidPieceIndex};
+use parking_lot::RwLock;
+
+use crate::type_aliases::FileInfos;
+
+use super::TorrentStorage;
+
+struct InMemoryPiece {
+    bytes: Box<[u8]>,
+}
+
+impl InMemoryPiece {
+    fn new(l: &Lengths) -> Self {
+        let v = vec![0; l.default_piece_length() as usize].into_boxed_slice();
+        Self { bytes: v }
+    }
+}
+
+pub struct InMemoryExampleStorage {
+    lengths: Lengths,
+    file_infos: FileInfos,
+    map: RwLock<HashMap<ValidPieceIndex, InMemoryPiece>>,
+    // TODO: chunk tracker - rename to PieceTracker and extract chunks out of it (only keep pieces)
+    // this sucker here would track chunks, and the storage above too.
+}
+
+impl InMemoryExampleStorage {
+    pub fn new(lengths: Lengths, file_infos: FileInfos) -> anyhow::Result<Self> {
+        // Max memory 128MiB. Make it tunable
+        let max_pieces = 128 * 1024 * 1024 / lengths.default_piece_length();
+        if max_pieces == 0 {
+            anyhow::bail!("pieces too large");
+        }
+
+        Ok(Self {
+            lengths,
+            file_infos,
+            map: RwLock::new(HashMap::new()),
+        })
+    }
+}
+
+impl TorrentStorage for InMemoryExampleStorage {
+    fn pread_exact(&self, file_id: usize, offset: u64, buf: &mut [u8]) -> anyhow::Result<()> {
+        let fi = &self.file_infos[file_id];
+        let abs_offset = fi.offset_in_torrent + offset;
+        let piece_id: u32 = (abs_offset / self.lengths.default_piece_length() as u64).try_into()?;
+        let piece_offset: usize =
+            (abs_offset % self.lengths.default_piece_length() as u64).try_into()?;
+        let piece_id = self.lengths.validate_piece_index(piece_id).context("bug")?;
+
+        let g = self.map.read();
+        let inmp = g.get(&piece_id).context("piece expired")?;
+        buf.copy_from_slice(&inmp.bytes[piece_offset..(piece_offset + buf.len())]);
+        Ok(())
+    }
+
+    fn pwrite_all(&self, file_id: usize, offset: u64, buf: &[u8]) -> anyhow::Result<()> {
+        let fi = &self.file_infos[file_id];
+        let abs_offset = fi.offset_in_torrent + offset;
+        let piece_id: u32 = (abs_offset / self.lengths.default_piece_length() as u64).try_into()?;
+        let piece_offset: usize =
+            (abs_offset % self.lengths.default_piece_length() as u64).try_into()?;
+        let piece_id = self.lengths.validate_piece_index(piece_id).context("bug")?;
+        let mut g = self.map.write();
+        let inmp = g
+            .entry(piece_id)
+            .or_insert_with(|| InMemoryPiece::new(&self.lengths));
+        inmp.bytes[piece_offset..(piece_offset + buf.len())].copy_from_slice(buf);
+        Ok(())
+    }
+
+    fn remove_file(&self, _file_id: usize, _filename: &Path) -> anyhow::Result<()> {
+        Ok(())
+    }
+
+    fn ensure_file_length(&self, _file_id: usize, _length: u64) -> anyhow::Result<()> {
+        Ok(())
+    }
+
+    fn take(&self) -> anyhow::Result<Box<dyn TorrentStorage>> {
+        let map = {
+            let mut g = self.map.write();
+            let mut repl = HashMap::new();
+            std::mem::swap(&mut *g, &mut repl);
+            repl
+        };
+        Ok(Box::new(Self {
+            lengths: self.lengths,
+            map: RwLock::new(map),
+            file_infos: self.file_infos.clone(),
+        }))
+    }
+}