diff --git a/src/ack.rs b/src/ack.rs
new file mode 100644
index 0000000..17f27bb
--- /dev/null
+++ b/src/ack.rs
@@ -0,0 +1,76 @@
+use std::time::Duration;
+
+use lapin::{options::{BasicAckOptions, BasicNackOptions}, types::DeliveryTag, Channel};
+use tokio::{select, sync::mpsc::{unbounded_channel, UnboundedReceiver, UnboundedSender}, time::{sleep_until, Instant}};
+
+use crate::range_map::RangeMap;
+
+pub type AckResult = Result<(), bool>;
+
+pub struct AckBatcher {
+    max_wait: Duration,
+    chan: Channel,
+    recv: UnboundedReceiver<(DeliveryTag, AckResult)>,
+    pending: RangeMap<DeliveryTag, AckResult>,
+    acked: DeliveryTag,
+}
+
+static ACK_BUFFER_LEN: usize = 1_000;
+
+impl AckBatcher {
+    pub fn new(max_wait: Duration, chan: Channel) -> (UnboundedSender<(DeliveryTag, AckResult)>, Self) {
+        let (send, recv) = unbounded_channel();
+        (send, Self { max_wait, chan, recv, pending: Default::default(), acked: 0 })
+    }
+
+    fn enqueue(&mut self, tag: DeliveryTag, res: AckResult) {
+        self.pending.insert(tag..tag+1, res);
+    }
+
+    fn ready(&self) -> bool {
+        self.pending.peek_first().is_some_and(|(range, _)| range.start == &(self.acked + 1))
+    }
+
+    pub async fn run(mut self) -> lapin::Result<()> {
+        let mut not_before = Instant::now();
+        let mut buffer = Vec::with_capacity(ACK_BUFFER_LEN);
+
+        loop {
+            let mut data_good = false;
+            let mut time_good = false;
+            while !(time_good && data_good) {
+                select! {
+                    num_received = self.recv.recv_many(&mut buffer, ACK_BUFFER_LEN) => {
+                        if num_received == 0 { println!("ack done"); return Ok(()); }
+                        for (tag, result) in buffer.drain(..) {
+                            //println!("rm.insert({}..{}+1, {:?}); rm.check_invariants();", tag, tag, &result);
+                            self.enqueue(tag, result);
+                            data_good = data_good || tag == self.acked + 1;
+                        }
+                    }
+                    _ = sleep_until(not_before), if !time_good => time_good = true
+                }
+            }
+
+            println!("ack status {:?}", self.pending);
+            loop {
+                let (ack_range, res) = self.pending.peek_first().unwrap();
+                let ack_to = ack_range.end - 1;
+                let res = *res;
+                self.pending.drop_first();
+
+                println!("ack sending {} {:?}", ack_to, res);
+                //println!("rm.drop_first(); rm.check_invariants();");
+                match res {
+                    Ok(()) => self.chan.basic_ack(ack_to, BasicAckOptions { multiple: true }).await,
+                    Err(requeue) => self.chan.basic_nack(ack_to, BasicNackOptions { multiple: true, requeue }).await,
+                }?;
+
+                self.acked = ack_to;
+                if !self.ready() { break; }
+            }
+            println!("ack sleep");
+            not_before = Instant::now() + self.max_wait;
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index ab76217..0d3929c 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,6 +1,10 @@
 #![feature(async_closure)]
+#![feature(btree_cursors)]
+#![feature(let_chains)]
 
+mod ack;
 mod processor;
+pub mod range_map;
 
 use std::time::Duration;
 
@@ -13,6 +17,7 @@ use tokio::{signal, time::sleep};
 use crate::processor::Processor;
 
 static QUEUE_COUNT: usize = 10;
+static SEND_COUNT: usize = 10;
 
 #[tokio::main]
 async fn main() -> Result<()> {
@@ -68,7 +73,7 @@ async fn broker_connect() -> lapin::Result<Connection> {
 struct Test { int: usize }
 
 async fn sender(conn: Connection, chan: Channel) -> lapin::Result<()> {
-    for int in 0..50_000 {
+    for int in 0..SEND_COUNT {
         if int % 1000 == 0 { println!("Sending {}", int) };
         let payload = Test { int };
         let confirm = chan.basic_publish(
@@ -85,12 +90,12 @@ async fn sender(conn: Connection, chan: Channel) -> lapin::Result<()> {
     Ok(())
 }
 
-async fn process(test: Test, i: usize) -> Result<()> {
+async fn process(_test: Test, _i: usize) -> Result<()> {
     let (dur, fail) = {
         let mut rng = thread_rng();
         (Duration::from_millis(rng.gen_range(1000..10000)), rng.gen_bool(0.01))
     };
     sleep(dur).await;
-    //if fail { println!("{} Fail {} {:?}", i, test.int, dur); }
+    //if fail { println!("{} Fail {} {:?}", _i, _test.int, dur); }
     if fail { Err(anyhow!("oops")) } else { Ok(()) }
 }
diff --git a/src/processor.rs b/src/processor.rs
index 1dd21dc..548b251 100644
--- a/src/processor.rs
+++ b/src/processor.rs
@@ -1,18 +1,20 @@
-use std::{collections::BTreeMap, future::Future, time::Duration};
+use std::{future::Future, time::Duration};
 
 use anyhow::Result;
 use futures_lite::prelude::*;
-use lapin::{options::{BasicAckOptions, BasicCancelOptions, BasicConsumeOptions, BasicNackOptions, BasicQosOptions}, types::{DeliveryTag, FieldTable, ShortString, ShortUInt}, Channel, Connection};
+use lapin::{options::{BasicCancelOptions, BasicConsumeOptions, BasicQosOptions}, types::{DeliveryTag, FieldTable, ShortString, ShortUInt}, Channel, Connection};
 use serde::de::DeserializeOwned;
-use tokio::{select, sync::mpsc::{unbounded_channel, UnboundedReceiver, UnboundedSender}, task::JoinSet, time::{sleep_until, Instant}};
+use tokio::{sync::mpsc::UnboundedSender, task::JoinSet};
 use tokio_util::task::TaskTracker;
 
+use crate::ack::{AckBatcher, AckResult};
+
 pub struct Processor {
     conn: Connection,
     chan: Channel,
     cons_tags: Vec<ShortString>,
     join_set: JoinSet<lapin::Result<()>>,
-    ack_sink: UnboundedSender<(DeliveryTag, Result<(), bool>)>,
+    ack_sink: UnboundedSender<(DeliveryTag, AckResult)>,
 }
 
 impl Processor {
@@ -86,71 +88,3 @@ impl Processor {
         conn.close(0, "").await
     }
 }
-
-struct AckBatcher {
-    max_wait: Duration,
-    chan: Channel,
-    recv: UnboundedReceiver<(DeliveryTag, Result<(), bool>)>,
-    pending: BTreeMap<DeliveryTag, Result<(), bool>>,
-    acked: DeliveryTag,
-}
-
-impl AckBatcher {
-    fn new(max_wait: Duration, chan: Channel) -> (UnboundedSender<(DeliveryTag, Result<(), bool>)>, Self) {
-        let (send, recv) = unbounded_channel();
-        (send, Self { max_wait, chan, recv, pending: Default::default(), acked: 0 })
-    }
-
-    fn enqueue(&mut self, tag: DeliveryTag, res: Result<(), bool>) {
-        let inserted = self.pending.insert(tag, res);
-        debug_assert_eq!(inserted, None);
-    }
-
-    fn ready(&self) -> bool {
-        self.pending.keys().next() == Some(&(self.acked + 1))
-    }
-
-    async fn run(mut self) -> lapin::Result<()> {
-        let mut not_before = Instant::now();
-
-        loop {
-            let mut data_good = false;
-            let mut time_good = false;
-            while !(time_good && data_good) {
-                select! {
-                    next = self.recv.recv() => {
-                        match next {
-                            Some((tag, result)) => {
-                                self.enqueue(tag, result);
-                                data_good = data_good || tag == self.acked + 1;
-                            },
-                            //None => return Ok(()),
-                            None => { println!("ack done"); return Ok(()) },
-                        }
-                    }
-                    _ = sleep_until(not_before), if !time_good => time_good = true
-                }
-            }
-
-            println!("ack status {:?}", self.pending.len());
-            loop {
-                let (mut ack_to, res) = self.pending.pop_first().unwrap();
-                while self.pending.first_key_value() == Some((&(ack_to + 1), &res)) {
-                    self.pending.pop_first();
-                    ack_to += 1;
-                }
-
-                println!("ack sending {} {:?}", ack_to, res);
-                match res {
-                    Ok(()) => self.chan.basic_ack(ack_to, BasicAckOptions { multiple: true }).await,
-                    Err(requeue) => self.chan.basic_nack(ack_to, BasicNackOptions { multiple: true, requeue }).await,
-                }?;
-
-                self.acked = ack_to;
-                if !self.ready() { break; }
-            }
-            println!("ack sleep");
-            not_before = Instant::now() + self.max_wait;
-        }
-    }
-}
diff --git a/src/range_map.rs b/src/range_map.rs
new file mode 100644
index 0000000..ce5ad33
--- /dev/null
+++ b/src/range_map.rs
@@ -0,0 +1,247 @@
+use std::{cmp::Ordering, collections::BTreeMap, fmt::Debug, ops::{Bound, Range}};
+
+#[derive(Clone, Debug)]
+pub struct RangeMap<K, V> {
+    ranges: BTreeMap<K, Option<V>>,
+}
+
+impl<K: Debug + Ord, V: Debug + PartialEq> RangeMap<K, V> {
+    pub fn insert(&mut self, range: Range<K>, val: V) {
+        if range.is_empty() { return; }
+        let Range { start, end } = range;
+
+        let mut curs = self.ranges.upper_bound_mut(Bound::Included(&start));
+        /*
+        print!("{:?} ", curs.peek_prev());
+        print!("{:?} ", curs.key_value());
+        println!("{:?}", curs.peek_next());
+        */
+        if let Some((key, old_val)) = curs.key_value_mut() && key == &start {
+            *old_val = Some(val);
+        } else {
+            curs.insert_after(start, Some(val));
+            curs.move_next();
+        }
+        while curs.as_cursor().peek_prev().map(|(_, v)| v) == curs.value() {
+            curs.remove_current_and_move_back();
+        }
+        curs.move_next();
+
+        /*
+        print!("{:?} ", curs.peek_prev());
+        print!("{:?} ", curs.key_value());
+        println!("{:?}", curs.peek_next());
+        */
+
+        let mut next_val = None;
+        loop {
+            match curs.key().map(|key| key.cmp(&end)) {
+                Some(Ordering::Less) => { // Delete entry but remember value as potential next value
+                    next_val = curs.remove_current().unwrap().1;
+                },
+                Some(Ordering::Equal) => break, // Already correct
+                _ => { // Next entry is missing or beyond end
+                    curs.insert_before(end, next_val);
+                    break;
+                },
+            }
+        }
+
+        while curs.as_cursor().peek_prev().map(|(_, v)| v) == curs.value() {
+            curs.remove_current();
+        }
+    }
+
+    pub fn drop_first(&mut self) {
+        if self.ranges.pop_first().is_some() { // Remove first
+            if self.ranges.iter().next().is_some_and(|(_, val)| val.is_none()) {
+                // Potentially clean up a single empty range after
+                self.ranges.pop_first();
+            }
+        }
+    }
+
+    #[cfg(test)]
+    fn check_invariants(&self) where V: Debug {
+        use std::iter::zip;
+
+        if let Some((_, val)) = self.ranges.first_key_value() {
+            assert!(val.is_some());
+            assert!(self.ranges.len() >= 2);
+
+            let (_, last_val) = self.ranges.last_key_value().unwrap();
+            assert!(last_val.is_none());
+        }
+
+        for (a, b) in zip(self.ranges.values(), self.ranges.values().skip(1)) {
+            assert_ne!(a, b);
+        }
+    }
+}
+
+impl<K, V> RangeMap<K, V> {
+    pub fn peek_first(&self) -> Option<(Range<&K>, &V)> {
+        let mut iter = self.ranges.iter();
+        let (start, val) = iter.next()?;
+        let (end, _) = iter.next().unwrap();
+        Some((start..end, val.as_ref().unwrap()))
+    }
+
+    pub fn clear(&mut self) { self.ranges.clear(); }
+
+    pub fn is_empty(&self) -> bool { self.ranges.is_empty() }
+}
+
+impl<K, V> Default for RangeMap<K, V> {
+    fn default() -> Self {
+        Self { ranges: Default::default() }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn basic() {
+        let mut rm = RangeMap::default();
+
+        for (i, (insert, expected)) in [
+            (None,              None                ),
+            (Some((5..10, 50)), Some((&5..&10, &50))),
+            (None,              None                ),
+            (Some((5..10, 50)), Some((&5..&10, &50))),
+            (Some((1.. 5, 10)), Some((&1..& 5, &10))),
+            (None             , Some((&5..&10, &50))),
+            (Some((1.. 3, 10)), Some((&1..& 3, &10))),
+            (None             , Some((&5..&10, &50))),
+            (Some((1.. 7, 10)), Some((&1..& 7, &10))),
+            (None             , Some((&7..&10, &50))),
+            (Some((1..10, 10)), Some((&1..&10, &10))),
+            (None             , None                ),
+            (Some((5..10, 50)), Some((&5..&10, &50))),
+            (Some((1..12, 10)), Some((&1..&12, &10))),
+            (None             , None                ),
+            (Some((5..10, 50)), Some((&5..&10, &50))),
+        ].into_iter().enumerate() {
+            match insert {
+                Some((k, v)) => rm.insert(k, v),
+                None => rm.drop_first(),
+            }
+            rm.check_invariants();
+            assert_eq!(rm.peek_first(), expected, "Failed at operation {}", i);
+        }
+    }
+
+    #[test]
+    fn generated() {
+        let mut rm = RangeMap::<usize, Result<(), bool>>::default();
+        rm.insert(59..59+1, Ok(())); rm.check_invariants();
+        rm.insert(80..80+1, Ok(())); rm.check_invariants();
+        rm.insert(100..100+1, Ok(())); rm.check_invariants();
+        rm.insert(86..86+1, Ok(())); rm.check_invariants();
+        rm.insert(98..98+1, Ok(())); rm.check_invariants();
+        rm.insert(70..70+1, Ok(())); rm.check_invariants();
+        rm.insert(39..39+1, Ok(())); rm.check_invariants();
+        rm.insert(35..35+1, Ok(())); rm.check_invariants();
+        rm.insert(89..89+1, Ok(())); rm.check_invariants();
+        rm.insert(94..94+1, Ok(())); rm.check_invariants();
+        rm.insert(77..77+1, Ok(())); rm.check_invariants();
+        rm.insert(82..82+1, Ok(())); rm.check_invariants();
+        rm.insert(6..6+1, Ok(())); rm.check_invariants();
+        rm.insert(15..15+1, Ok(())); rm.check_invariants();
+        rm.insert(5..5+1, Ok(())); rm.check_invariants();
+        rm.insert(8..8+1, Ok(())); rm.check_invariants();
+        rm.insert(10..10+1, Ok(())); rm.check_invariants();
+        rm.insert(17..17+1, Ok(())); rm.check_invariants();
+        rm.insert(25..25+1, Ok(())); rm.check_invariants();
+        rm.insert(44..44+1, Ok(())); rm.check_invariants();
+        rm.insert(43..43+1, Ok(())); rm.check_invariants();
+        rm.insert(55..55+1, Ok(())); rm.check_invariants();
+        rm.insert(63..63+1, Ok(())); rm.check_invariants();
+        rm.insert(24..24+1, Ok(())); rm.check_invariants();
+        rm.insert(36..36+1, Ok(())); rm.check_invariants();
+        rm.insert(51..51+1, Ok(())); rm.check_invariants();
+        rm.insert(11..11+1, Ok(())); rm.check_invariants();
+        rm.insert(1..1+1, Ok(())); rm.check_invariants();
+        rm.drop_first(); rm.check_invariants();
+        rm.insert(71..71+1, Ok(())); rm.check_invariants();
+        rm.insert(75..75+1, Ok(())); rm.check_invariants();
+        rm.insert(74..74+1, Ok(())); rm.check_invariants();
+        rm.insert(26..26+1, Ok(())); rm.check_invariants();
+        rm.insert(97..97+1, Ok(())); rm.check_invariants();
+        rm.insert(66..66+1, Ok(())); rm.check_invariants();
+        rm.insert(49..49+1, Ok(())); rm.check_invariants();
+        rm.insert(69..69+1, Ok(())); rm.check_invariants();
+        rm.insert(64..64+1, Ok(())); rm.check_invariants();
+        rm.insert(38..38+1, Ok(())); rm.check_invariants();
+        rm.insert(48..48+1, Ok(())); rm.check_invariants();
+        rm.insert(62..62+1, Ok(())); rm.check_invariants();
+        rm.insert(46..46+1, Ok(())); rm.check_invariants();
+        rm.insert(57..57+1, Ok(())); rm.check_invariants();
+        rm.insert(13..13+1, Ok(())); rm.check_invariants();
+        rm.insert(30..30+1, Ok(())); rm.check_invariants();
+        rm.insert(99..99+1, Ok(())); rm.check_invariants();
+        rm.insert(18..18+1, Ok(())); rm.check_invariants();
+        rm.insert(40..40+1, Ok(())); rm.check_invariants();
+        rm.insert(84..84+1, Ok(())); rm.check_invariants();
+        rm.insert(4..4+1, Ok(())); rm.check_invariants();
+        rm.insert(9..9+1, Ok(())); rm.check_invariants();
+        rm.insert(14..14+1, Ok(())); rm.check_invariants();
+        rm.insert(16..16+1, Ok(())); rm.check_invariants();
+        rm.insert(12..12+1, Ok(())); rm.check_invariants();
+        rm.insert(53..53+1, Ok(())); rm.check_invariants();
+        rm.insert(21..21+1, Ok(())); rm.check_invariants();
+        rm.insert(54..54+1, Ok(())); rm.check_invariants();
+        rm.insert(28..28+1, Ok(())); rm.check_invariants();
+        rm.insert(68..68+1, Ok(())); rm.check_invariants();
+        rm.insert(95..95+1, Ok(())); rm.check_invariants();
+        rm.insert(90..90+1, Ok(())); rm.check_invariants();
+        rm.insert(73..73+1, Ok(())); rm.check_invariants();
+        rm.insert(83..83+1, Ok(())); rm.check_invariants();
+        rm.insert(32..32+1, Ok(())); rm.check_invariants();
+        rm.insert(27..27+1, Ok(())); rm.check_invariants();
+        rm.insert(34..34+1, Ok(())); rm.check_invariants();
+        rm.insert(61..61+1, Ok(())); rm.check_invariants();
+        rm.insert(2..2+1, Ok(())); rm.check_invariants();
+        rm.drop_first(); rm.check_invariants();
+        rm.insert(31..31+1, Ok(())); rm.check_invariants();
+        rm.insert(20..20+1, Ok(())); rm.check_invariants();
+        rm.insert(47..47+1, Ok(())); rm.check_invariants();
+        rm.insert(52..52+1, Ok(())); rm.check_invariants();
+        rm.insert(87..87+1, Ok(())); rm.check_invariants();
+        rm.insert(37..37+1, Ok(())); rm.check_invariants();
+        rm.insert(22..22+1, Ok(())); rm.check_invariants();
+        rm.insert(42..42+1, Ok(())); rm.check_invariants();
+        rm.insert(33..33+1, Ok(())); rm.check_invariants();
+        rm.insert(23..23+1, Ok(())); rm.check_invariants();
+        rm.insert(60..60+1, Ok(())); rm.check_invariants();
+        rm.insert(65..65+1, Ok(())); rm.check_invariants();
+        rm.insert(19..19+1, Ok(())); rm.check_invariants();
+        rm.insert(3..3+1, Ok(())); rm.check_invariants();
+        rm.drop_first(); rm.check_invariants();
+        rm.insert(85..85+1, Ok(())); rm.check_invariants();
+        rm.insert(67..67+1, Ok(())); rm.check_invariants();
+        rm.insert(76..76+1, Ok(())); rm.check_invariants();
+        rm.insert(72..72+1, Ok(())); rm.check_invariants();
+        rm.insert(78..78+1, Ok(())); rm.check_invariants();
+        rm.insert(50..50+1, Ok(())); rm.check_invariants();
+        rm.insert(96..96+1, Ok(())); rm.check_invariants();
+        rm.insert(45..45+1, Ok(())); rm.check_invariants();
+        rm.insert(7..7+1, Ok(())); rm.check_invariants();
+        rm.insert(93..93+1, Ok(())); rm.check_invariants();
+        rm.insert(92..92+1, Ok(())); rm.check_invariants();
+        rm.drop_first(); rm.check_invariants();
+        rm.insert(56..56+1, Ok(())); rm.check_invariants();
+        rm.insert(88..88+1, Ok(())); rm.check_invariants();
+        rm.insert(29..29+1, Ok(())); rm.check_invariants();
+        rm.insert(58..58+1, Ok(())); rm.check_invariants();
+        rm.insert(91..91+1, Ok(())); rm.check_invariants();
+        rm.insert(41..41+1, Ok(())); rm.check_invariants();
+        rm.insert(81..81+1, Ok(())); rm.check_invariants();
+        rm.insert(79..79+1, Ok(())); rm.check_invariants();
+        rm.drop_first(); rm.check_invariants();
+        rm.drop_first(); rm.check_invariants();
+        rm.drop_first(); rm.check_invariants();
+    }
+}