From 816838cdf081ad83242eb478aa8261ffa2c87442 Mon Sep 17 00:00:00 2001
From: Igor Katson <igor.katson@gmail.com>
Date: Thu, 12 Sep 2024 23:59:50 +0100
Subject: [PATCH 1/2] Fastresume: check at least one piece from each file

---
 .../src/torrent_state/initializing.rs         | 55 +++++++++++++++----
 1 file changed, 44 insertions(+), 11 deletions(-)

diff --git a/crates/librqbit/src/torrent_state/initializing.rs b/crates/librqbit/src/torrent_state/initializing.rs
index 868cea6..ed4e228 100644
--- a/crates/librqbit/src/torrent_state/initializing.rs
+++ b/crates/librqbit/src/torrent_state/initializing.rs
@@ -100,27 +100,60 @@ impl TorrentStateInitializing {
 
             use rand::seq::SliceRandom;
 
-            let mut have_pieces = hp
-                .as_slice()
-                .iter_ones()
-                .filter_map(|i| self.shared.lengths.validate_piece_index(i.try_into().ok()?))
-                .collect_vec();
-            have_pieces.shuffle(&mut rand::thread_rng());
+            let mut to_validate = BF::from_boxed_slice(
+                vec![0u8; self.shared.lengths.piece_bitfield_bytes()].into_boxed_slice(),
+            );
+            let mut queue = hp.as_slice().to_owned();
 
-            // Validate a certain threshold of fastresume pieces with decreasing probability of actual disk reads.
-            for (tmp_id, hpiece) in have_pieces.iter().enumerate() {
+            // Validate at least one piece from each file, if we claim we have it.
+            for fi in self.shared.file_infos.iter() {
+                let prange = fi.piece_range_usize();
+                let offset = prange.start;
+                for piece_id in hp
+                    .as_slice()
+                    .get(fi.piece_range_usize())
+                    .into_iter()
+                    .flat_map(|s| s.iter_ones())
+                    .map(|pid| pid + offset)
+                    .take(1)
+                {
+                    to_validate.set(piece_id, true);
+                    queue.set(piece_id, false);
+                }
+            }
+
+            // For all the remaining pieces we claim we have, validate them with decreasing probability.
+            let mut queue = queue.iter_ones().collect_vec();
+            queue.shuffle(&mut rand::thread_rng());
+            for (tmp_id, piece_id) in queue.into_iter().enumerate() {
                 let denom: u32 = (tmp_id + 1).min(50).try_into().unwrap();
-                if rand::thread_rng().gen_ratio(1, denom) && fo.check_piece(*hpiece).is_err() {
+                if rand::thread_rng().gen_ratio(1, denom) {
+                    to_validate.set(piece_id, true);
+                }
+            }
+
+            let to_validate_count = to_validate.count_ones();
+            for (id, piece_id) in to_validate
+                .iter_ones()
+                .filter_map(|id| {
+                    self.shared
+                        .lengths
+                        .validate_piece_index(id.try_into().ok()?)
+                })
+                .enumerate()
+            {
+                if fo.check_piece(piece_id).is_err() {
                     return true;
                 }
 
                 #[allow(clippy::cast_possible_truncation)]
                 let progress = (self.shared.lengths.total_length() as f64
-                    / have_pieces.len() as f64
-                    * (tmp_id + 1) as f64) as u64;
+                    / to_validate_count as f64
+                    * (id + 1) as f64) as u64;
                 let progress = progress.min(self.shared.lengths.total_length());
                 self.checked_bytes.store(progress, Ordering::Relaxed);
             }
+
             false
         });
 

From 00daae97eda70cf444ad44b27625f71a9f60cadc Mon Sep 17 00:00:00 2001
From: Igor Katson <igor.katson@gmail.com>
Date: Fri, 13 Sep 2024 00:20:37 +0100
Subject: [PATCH 2/2] Reorder removal so that mmap is removed before storage

---
 crates/librqbit/src/bitv.rs    |  7 +++++++
 crates/librqbit/src/session.rs | 16 ++++++++--------
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/crates/librqbit/src/bitv.rs b/crates/librqbit/src/bitv.rs
index f3c0129..38ce994 100644
--- a/crates/librqbit/src/bitv.rs
+++ b/crates/librqbit/src/bitv.rs
@@ -8,6 +8,7 @@ use bitvec::{
     vec::BitVec,
     view::{AsBits, AsMutBits},
 };
+use tracing::trace;
 
 pub trait BitV: Send + Sync {
     fn as_slice(&self) -> &BitSlice<u8, Msb0>;
@@ -24,6 +25,12 @@ pub struct MmapBitV {
     mmap: memmap2::MmapMut,
 }
 
+impl Drop for MmapBitV {
+    fn drop(&mut self) {
+        trace!("dropping MmapBitV, this should unmap the .bitv file")
+    }
+}
+
 impl MmapBitV {
     pub fn new(file: File) -> anyhow::Result<Self> {
         let mmap =
diff --git a/crates/librqbit/src/session.rs b/crates/librqbit/src/session.rs
index 0522b7b..0ddf83e 100644
--- a/crates/librqbit/src/session.rs
+++ b/crates/librqbit/src/session.rs
@@ -1251,14 +1251,6 @@ impl Session {
             debug!("error pausing torrent before deletion: {e:?}")
         }
 
-        if let Some(p) = self.persistence.as_ref() {
-            if let Err(e) = p.delete(id).await {
-                error!(error=?e, "error deleting torrent from persistence database");
-            } else {
-                debug!(?id, "deleted torrent from persistence database")
-            }
-        }
-
         let storage = removed
             .with_state_mut(|s| match s.take() {
                 ManagedTorrentState::Initializing(p) => p.files.take().ok(),
@@ -1277,6 +1269,14 @@ impl Session {
             .map(Ok)
             .unwrap_or_else(|| removed.shared.storage_factory.create(removed.shared()));
 
+        if let Some(p) = self.persistence.as_ref() {
+            if let Err(e) = p.delete(id).await {
+                error!(error=?e, "error deleting torrent from persistence database");
+            } else {
+                debug!(?id, "deleted torrent from persistence database")
+            }
+        }
+
         match (storage, delete_files) {
             (Err(e), true) => return Err(e).context("torrent deleted, but could not delete files"),
             (Ok(storage), true) => {