From 58a03bd3c146eaa7390bdcc822abf7ce91393fad Mon Sep 17 00:00:00 2001
From: tison <wander4096@gmail.com>
Date: Wed, 7 May 2025 17:58:04 +0800
Subject: [PATCH 1/6] feat: implmenet bounded pool replenishment

Signed-off-by: tison <wander4096@gmail.com>
---
 examples/postgres/src/main.rs | 11 +++++++--
 fastpool/src/bounded.rs       | 45 +++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+), 2 deletions(-)

diff --git a/examples/postgres/src/main.rs b/examples/postgres/src/main.rs
index e4c225e..bc09b93 100644
--- a/examples/postgres/src/main.rs
+++ b/examples/postgres/src/main.rs
@@ -16,17 +16,17 @@ use std::str::FromStr;
 use std::sync::Arc;
 use std::time::Duration;
 
+use fastpool::ObjectStatus;
 use fastpool::bounded::Object;
 use fastpool::bounded::Pool;
 use fastpool::bounded::PoolConfig;
-use fastpool::ObjectStatus;
 use futures::future::BoxFuture;
-use sqlx::postgres::PgConnectOptions;
 use sqlx::Acquire;
 use sqlx::ConnectOptions;
 use sqlx::Connection;
 use sqlx::PgConnection;
 use sqlx::TransactionManager;
+use sqlx::postgres::PgConnectOptions;
 
 #[derive(Debug, Clone)]
 pub struct ConnectionPool {
@@ -46,6 +46,13 @@ impl ConnectionPool {
                 tokio::time::sleep(REAP_IDLE_INTERVAL).await;
                 if let Some(pool) = weak_pool.upgrade() {
                     pool.retain(|_, m| m.last_used().elapsed() < IDLE_TIMEOUT);
+
+                    let status = pool.status();
+                    let gap = status.max_size - status.current_size;
+                    match pool.replenish(gap).await {
+                        Ok(n) => println!("Replenished {n} connections"),
+                        Err(err) => eprintln!("Failed to replenish connections: {err}"),
+                    }
                 } else {
                     break;
                 }
diff --git a/fastpool/src/bounded.rs b/fastpool/src/bounded.rs
index 13c119c..18e2efc 100644
--- a/fastpool/src/bounded.rs
+++ b/fastpool/src/bounded.rs
@@ -195,6 +195,51 @@ impl<M: ManageObject> Pool<M> {
         })
     }
 
+    /// Replenishes the pool with at most `most` number of new objects.
+    ///
+    /// * Returns `Ok(n)` if successfully replenished `n` objects.
+    /// * Returns `Ok(0)` if no replenishment is needed.
+    /// * Returns `Err(e)` if an error occurred while replenishing.
+    pub async fn replenish(&self, mut most: usize) -> Result<usize, M::Error> {
+        let permit = loop {
+            if most == 0 {
+                return Ok(0);
+            }
+
+            match self.permits.try_acquire(most) {
+                Some(permit) => break permit,
+                None => {
+                    most = most.min(self.permits.available_permits());
+                    continue;
+                }
+            }
+        };
+
+        most = most.saturating_sub(self.slots.lock().deque.len());
+        if most == 0 {
+            return Ok(0);
+        }
+
+        let mut idles = vec![];
+        for _ in 0..most {
+            let object = self.manager.create().await?;
+            let state = ObjectState {
+                o: object,
+                status: ObjectStatus::default(),
+            };
+            idles.push(state);
+        }
+
+        let mut slots = self.slots.lock();
+        slots.deque.extend(idles);
+        slots.current_size += most;
+        drop(slots);
+
+        // ensure the permit is held at this point
+        drop(permit);
+        Ok(most)
+    }
+
     /// Retrieves an [`Object`] from this [`Pool`].
     ///
     /// This method should be called with a pool wrapped in an [`Arc`]. If the pool reaches the

From e272ce337f01305f8a98cb079d985434c8257103 Mon Sep 17 00:00:00 2001
From: tison <wander4096@gmail.com>
Date: Wed, 7 May 2025 18:24:00 +0800
Subject: [PATCH 2/6] fixup

Signed-off-by: tison <wander4096@gmail.com>
---
 examples/postgres/src/main.rs |  5 +---
 fastpool/src/bounded.rs       | 53 ++++++++++++++++++-----------------
 2 files changed, 28 insertions(+), 30 deletions(-)

diff --git a/examples/postgres/src/main.rs b/examples/postgres/src/main.rs
index bc09b93..83fd8c1 100644
--- a/examples/postgres/src/main.rs
+++ b/examples/postgres/src/main.rs
@@ -49,10 +49,7 @@ impl ConnectionPool {
 
                     let status = pool.status();
                     let gap = status.max_size - status.current_size;
-                    match pool.replenish(gap).await {
-                        Ok(n) => println!("Replenished {n} connections"),
-                        Err(err) => eprintln!("Failed to replenish connections: {err}"),
-                    }
+                    pool.replenish(gap).await;
                 } else {
                     break;
                 }
diff --git a/fastpool/src/bounded.rs b/fastpool/src/bounded.rs
index 18e2efc..5cf7137 100644
--- a/fastpool/src/bounded.rs
+++ b/fastpool/src/bounded.rs
@@ -197,47 +197,48 @@ impl<M: ManageObject> Pool<M> {
 
     /// Replenishes the pool with at most `most` number of new objects.
     ///
-    /// * Returns `Ok(n)` if successfully replenished `n` objects.
-    /// * Returns `Ok(0)` if no replenishment is needed.
-    /// * Returns `Err(e)` if an error occurred while replenishing.
-    pub async fn replenish(&self, mut most: usize) -> Result<usize, M::Error> {
-        let permit = loop {
-            if most == 0 {
-                return Ok(0);
-            }
-
-            match self.permits.try_acquire(most) {
-                Some(permit) => break permit,
-                None => {
-                    most = most.min(self.permits.available_permits());
-                    continue;
+    /// Returns `n` where `n` is the number of objects added to the pool.
+    pub async fn replenish(&self, most: usize) -> usize {
+        let permit = {
+            let mut n = most;
+            loop {
+                match self.permits.try_acquire(most) {
+                    Some(permit) => break permit,
+                    None => {
+                        n = n.min(self.permits.available_permits());
+                        continue;
+                    }
                 }
             }
         };
+        if permit.permits() == 0 {
+            return 0;
+        }
 
-        most = most.saturating_sub(self.slots.lock().deque.len());
-        if most == 0 {
-            return Ok(0);
+        let idle_count = self.slots.lock().deque.len();
+        let gap = permit.permits().saturating_sub(idle_count);
+        if gap == 0 {
+            return 0;
         }
 
         let mut idles = vec![];
-        for _ in 0..most {
-            let object = self.manager.create().await?;
-            let state = ObjectState {
-                o: object,
-                status: ObjectStatus::default(),
-            };
-            idles.push(state);
+        for _ in 0..gap {
+            if let Ok(o) = self.manager.create().await {
+                let status = ObjectStatus::default();
+                let state = ObjectState { o, status };
+                idles.push(state);
+            }
         }
+        let replenished = idles.len();
 
         let mut slots = self.slots.lock();
+        slots.current_size += replenished;
         slots.deque.extend(idles);
-        slots.current_size += most;
         drop(slots);
 
         // ensure the permit is held at this point
         drop(permit);
-        Ok(most)
+        replenished
     }
 
     /// Retrieves an [`Object`] from this [`Pool`].

From b32c300b6fc8861f956806fddb82ed9a86a57c87 Mon Sep 17 00:00:00 2001
From: tison <wander4096@gmail.com>
Date: Wed, 7 May 2025 19:40:31 +0800
Subject: [PATCH 3/6] more

Signed-off-by: tison <wander4096@gmail.com>
---
 Cargo.lock              |  4 ++--
 fastpool/Cargo.toml     |  2 +-
 fastpool/src/bounded.rs | 16 +++++++++++-----
 3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index c701e53..dbafbab 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -225,9 +225,9 @@ dependencies = [
 
 [[package]]
 name = "mea"
-version = "0.3.2"
+version = "0.3.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fb74bfea0c87e63e0c96aa35c2c5251c552f1c935f0e47ddedded0db3f5f373e"
+checksum = "8f95fb3fd830a995cad9668051189c4dcb53ca812e80d58e0781f617e91b4ee2"
 dependencies = [
  "slab",
 ]
diff --git a/fastpool/Cargo.toml b/fastpool/Cargo.toml
index 70a5814..6bb599b 100644
--- a/fastpool/Cargo.toml
+++ b/fastpool/Cargo.toml
@@ -26,7 +26,7 @@ repository.workspace = true
 rust-version.workspace = true
 
 [dependencies]
-mea = { version = "0.3.2" }
+mea = { version = "0.3.6" }
 scopeguard = { version = "1.2.0" }
 
 [dev-dependencies]
diff --git a/fastpool/src/bounded.rs b/fastpool/src/bounded.rs
index 5cf7137..1dfdce1 100644
--- a/fastpool/src/bounded.rs
+++ b/fastpool/src/bounded.rs
@@ -211,15 +211,21 @@ impl<M: ManageObject> Pool<M> {
                 }
             }
         };
+
         if permit.permits() == 0 {
             return 0;
         }
 
-        let idle_count = self.slots.lock().deque.len();
-        let gap = permit.permits().saturating_sub(idle_count);
-        if gap == 0 {
-            return 0;
-        }
+        let (gap, permit) = {
+            let mut permit = permit;
+            let idle_count = self.slots.lock().deque.len();
+            if idle_count >= permit.permits() {
+                return 0;
+            }
+
+            permit.release(idle_count);
+            (permit.permits(), permit)
+        };
 
         let mut idles = vec![];
         for _ in 0..gap {

From d89c4ff55d3af10709a5d306c4fb875bd9966fd1 Mon Sep 17 00:00:00 2001
From: tison <wander4096@gmail.com>
Date: Wed, 7 May 2025 21:06:20 +0800
Subject: [PATCH 4/6] tidy

Signed-off-by: tison <wander4096@gmail.com>
---
 fastpool/src/bounded.rs | 38 ++++++++++++++++++++------------------
 1 file changed, 20 insertions(+), 18 deletions(-)

diff --git a/fastpool/src/bounded.rs b/fastpool/src/bounded.rs
index 1dfdce1..920f332 100644
--- a/fastpool/src/bounded.rs
+++ b/fastpool/src/bounded.rs
@@ -197,9 +197,9 @@ impl<M: ManageObject> Pool<M> {
 
     /// Replenishes the pool with at most `most` number of new objects.
     ///
-    /// Returns `n` where `n` is the number of objects added to the pool.
+    /// Returns the number of objects that are actually replenished to the pool.
     pub async fn replenish(&self, most: usize) -> usize {
-        let permit = {
+        let mut permit = {
             let mut n = most;
             loop {
                 match self.permits.try_acquire(most) {
@@ -216,34 +216,36 @@ impl<M: ManageObject> Pool<M> {
             return 0;
         }
 
-        let (gap, permit) = {
-            let mut permit = permit;
-            let idle_count = self.slots.lock().deque.len();
-            if idle_count >= permit.permits() {
+        let gap = {
+            let idles = self.slots.lock().deque.len();
+            if idles >= permit.permits() {
                 return 0;
             }
 
-            permit.release(idle_count);
-            (permit.permits(), permit)
+            // exclude idle objects that already exists
+            permit.release(idles);
+            permit.permits()
         };
 
-        let mut idles = vec![];
+        let mut replenished = 0;
         for _ in 0..gap {
             if let Ok(o) = self.manager.create().await {
                 let status = ObjectStatus::default();
                 let state = ObjectState { o, status };
-                idles.push(state);
+
+                let mut slots = self.slots.lock();
+                slots.current_size += 1;
+                slots.deque.push_back(state);
+                drop(slots);
+
+                replenished += 1;
+                permit.release(1);
+            } else {
+                // always release one permit to unblock other waiters
+                permit.release(1);
             }
         }
-        let replenished = idles.len();
-
-        let mut slots = self.slots.lock();
-        slots.current_size += replenished;
-        slots.deque.extend(idles);
-        drop(slots);
 
-        // ensure the permit is held at this point
-        drop(permit);
         replenished
     }
 

From 4859eef0b74e4c805f31e454b5886bfdff0c6eef Mon Sep 17 00:00:00 2001
From: tison <wander4096@gmail.com>
Date: Wed, 7 May 2025 21:24:47 +0800
Subject: [PATCH 5/6] test and fix

Signed-off-by: tison <wander4096@gmail.com>
---
 fastpool/src/bounded.rs           |  9 ++--
 fastpool/tests/replenish_tests.rs | 75 +++++++++++++++++++++++++++++++
 2 files changed, 79 insertions(+), 5 deletions(-)
 create mode 100644 fastpool/tests/replenish_tests.rs

diff --git a/fastpool/src/bounded.rs b/fastpool/src/bounded.rs
index 920f332..115cbac 100644
--- a/fastpool/src/bounded.rs
+++ b/fastpool/src/bounded.rs
@@ -202,7 +202,7 @@ impl<M: ManageObject> Pool<M> {
         let mut permit = {
             let mut n = most;
             loop {
-                match self.permits.try_acquire(most) {
+                match self.permits.try_acquire(n) {
                     Some(permit) => break permit,
                     None => {
                         n = n.min(self.permits.available_permits());
@@ -239,11 +239,10 @@ impl<M: ManageObject> Pool<M> {
                 drop(slots);
 
                 replenished += 1;
-                permit.release(1);
-            } else {
-                // always release one permit to unblock other waiters
-                permit.release(1);
             }
+
+            // always release one permit to unblock other waiters
+            permit.release(1);
         }
 
         replenished
diff --git a/fastpool/tests/replenish_tests.rs b/fastpool/tests/replenish_tests.rs
new file mode 100644
index 0000000..b35cd9a
--- /dev/null
+++ b/fastpool/tests/replenish_tests.rs
@@ -0,0 +1,75 @@
+// Copyright 2025 FastLabs Developers
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::convert::Infallible;
+use std::sync::Arc;
+
+use fastpool::ManageObject;
+use fastpool::ObjectStatus;
+use fastpool::bounded::Pool;
+use fastpool::bounded::PoolConfig;
+
+#[tokio::test]
+async fn test_simple_replenish() {
+    #[derive(Default)]
+    struct Manager;
+
+    impl ManageObject for Manager {
+        type Object = ();
+        type Error = Infallible;
+
+        async fn create(&self) -> Result<Self::Object, Self::Error> {
+            Ok(())
+        }
+
+        async fn is_recyclable(
+            &self,
+            _o: &mut Self::Object,
+            _status: &ObjectStatus,
+        ) -> Result<(), Self::Error> {
+            Ok(())
+        }
+    }
+
+    const MAX_SIZE: usize = 2;
+
+    fn make_default() -> Arc<Pool<Manager>> {
+        Pool::new(PoolConfig::new(MAX_SIZE), Manager)
+    }
+
+    for i in 0..5 {
+        let pool = make_default();
+        let n = pool.replenish(i).await;
+        assert_eq!(n, i.min(MAX_SIZE));
+    }
+
+    // stage one idle object
+    {
+        let pool = make_default();
+        pool.get().await.unwrap();
+        let n = pool.replenish(2).await;
+        assert_eq!(n, 1);
+    }
+
+    // stage two idle objects
+    {
+        let pool = make_default();
+        let o1 = pool.get().await.unwrap();
+        let o2 = pool.get().await.unwrap();
+        drop((o1, o2));
+
+        let n = pool.replenish(2).await;
+        assert_eq!(n, 0);
+    }
+}

From 41a7caf5239f768ece2180cf36630684e133f7f5 Mon Sep 17 00:00:00 2001
From: tison <wander4096@gmail.com>
Date: Wed, 7 May 2025 21:51:17 +0800
Subject: [PATCH 6/6] catch up

Signed-off-by: tison <wander4096@gmail.com>
---
 Cargo.lock                        | 80 +++++++++++++++----------------
 fastpool/Cargo.toml               |  2 +-
 fastpool/src/bounded.rs           | 23 +++++++--
 fastpool/tests/replenish_tests.rs |  2 +-
 4 files changed, 61 insertions(+), 46 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index dbafbab..a6e9e17 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -75,9 +75,9 @@ checksum = "ace50bade8e6234aa140d9a2f552bbee1db4d353f69b8217bc503490fc1a9f26"
 
 [[package]]
 name = "backtrace"
-version = "0.3.74"
+version = "0.3.75"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8d82cb332cdfaed17ae235a638438ac4d4839913cc2af585c3c6746e8f8bee1a"
+checksum = "6806a6321ec58106fea15becdad98371e28d92ccbc7c8f1b3b6dd724fe8f1002"
 dependencies = [
  "addr2line",
  "cfg-if",
@@ -108,9 +108,9 @@ checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
 [[package]]
 name = "clap"
-version = "4.5.31"
+version = "4.5.37"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "027bb0d98429ae334a8698531da7077bdf906419543a35a55c2cb1b66437d767"
+checksum = "eccb054f56cbd38340b380d4a8e69ef1f02f1af43db2f0cc817a4774d80ae071"
 dependencies = [
  "clap_builder",
  "clap_derive",
@@ -118,9 +118,9 @@ dependencies = [
 
 [[package]]
 name = "clap_builder"
-version = "4.5.31"
+version = "4.5.37"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5589e0cba072e0f3d23791efac0fd8627b49c829c196a492e88168e6a669d863"
+checksum = "efd9466fac8543255d3b1fcad4762c5e116ffe808c8a3043d4263cd4fd4862a2"
 dependencies = [
  "anstream",
  "anstyle",
@@ -130,9 +130,9 @@ dependencies = [
 
 [[package]]
 name = "clap_derive"
-version = "4.5.28"
+version = "4.5.32"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bf4ced95c6f4a675af3da73304b9ac4ed991640c36374e4b46795c49e17cf1ed"
+checksum = "09176aae279615badda0765c0c0b3f6ed53f4709118af73cf4655d85d1530cd7"
 dependencies = [
  "heck",
  "proc-macro2",
@@ -166,9 +166,9 @@ checksum = "c7f84e12ccf0a7ddc17a6c41c93326024c42920d7ee630d04950e6926645c0fe"
 
 [[package]]
 name = "errno"
-version = "0.3.10"
+version = "0.3.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "33d852cb9b869c2a9b3df2f71a3074817f01e1844f839a144f5fcef059a4eb5d"
+checksum = "976dd42dc7e85965fe702eb8164f21f450704bdde31faefd6471dba214cb594e"
 dependencies = [
  "libc",
  "windows-sys 0.59.0",
@@ -203,15 +203,15 @@ checksum = "7943c866cc5cd64cbc25b2e01621d07fa8eb2a1a23160ee81ce38704e97b8ecf"
 
 [[package]]
 name = "libc"
-version = "0.2.170"
+version = "0.2.172"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "875b3680cb2f8f71bdcf9a30f38d48282f5d3c95cbf9b3fa57269bb5d5c06828"
+checksum = "d750af042f7ef4f724306de029d18836c26c1765a54a6a3f094cbd23a7267ffa"
 
 [[package]]
 name = "linux-raw-sys"
-version = "0.4.15"
+version = "0.9.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d26c52dbd32dccf2d10cac7725f8eae5296885fb5703b261f7d0a0739ec807ab"
+checksum = "cd945864f07fe9f5371a27ad7b52a172b4b499999f1d97574c9fa68373937e12"
 
 [[package]]
 name = "lock_api"
@@ -225,9 +225,9 @@ dependencies = [
 
 [[package]]
 name = "mea"
-version = "0.3.6"
+version = "0.3.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8f95fb3fd830a995cad9668051189c4dcb53ca812e80d58e0781f617e91b4ee2"
+checksum = "3dd4c034214a0a3656fafe3a600d6ea4f9329ec9a35168126ff548af33375fc0"
 dependencies = [
  "slab",
 ]
@@ -240,9 +240,9 @@ checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
 
 [[package]]
 name = "miniz_oxide"
-version = "0.8.5"
+version = "0.8.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8e3e04debbb59698c15bacbb6d93584a8c0ca9cc3213cb423d31f760d8843ce5"
+checksum = "3be647b768db090acb35d5ec5db2b0e1f1de11133ca123b9eacf5137868f892a"
 dependencies = [
  "adler2",
 ]
@@ -269,9 +269,9 @@ dependencies = [
 
 [[package]]
 name = "once_cell"
-version = "1.20.3"
+version = "1.21.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "945462a4b81e43c4e3ba96bd7b49d834c6f61198356aa858733bc4acf3cbe62e"
+checksum = "42f5e15c9953c5e4ccceeb2e7382a716482c34515315f7b03532b8b4e8393d2d"
 
 [[package]]
 name = "parking_lot"
@@ -304,27 +304,27 @@ checksum = "3b3cff922bd51709b605d9ead9aa71031d81447142d828eb4a6eba76fe619f9b"
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.94"
+version = "1.0.95"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a31971752e70b8b2686d7e46ec17fb38dad4051d94024c88df49b667caea9c84"
+checksum = "02b3e5e68a3a1a02aad3ec490a98007cbc13c37cbe84a3cd7b8e406d76e7f778"
 dependencies = [
  "unicode-ident",
 ]
 
 [[package]]
 name = "quote"
-version = "1.0.39"
+version = "1.0.40"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c1f1914ce909e1658d9907913b4b91947430c7d9be598b15a1912935b8c04801"
+checksum = "1885c039570dc00dcb4ff087a89e185fd56bae234ddc7f056a945bf36467248d"
 dependencies = [
  "proc-macro2",
 ]
 
 [[package]]
 name = "redox_syscall"
-version = "0.5.10"
+version = "0.5.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0b8c0c260b63a8219631167be35e6a988e9554dbd323f8bd08439c8ed1302bd1"
+checksum = "928fca9cf2aa042393a8325b9ead81d2f0df4cb12e1e24cef072922ccd99c5af"
 dependencies = [
  "bitflags",
 ]
@@ -337,9 +337,9 @@ checksum = "719b953e2095829ee67db738b3bfa9fa368c94900df327b3f07fe6e794d2fe1f"
 
 [[package]]
 name = "rustix"
-version = "0.38.44"
+version = "1.0.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fdb5bc1ae2baa591800df16c9ca78619bf65c0488b41b96ccec5d11220d8c154"
+checksum = "c71e83d6afe7ff64890ec6b71d6a69bb8a610ab78ce364b3352876bb4c801266"
 dependencies = [
  "bitflags",
  "errno",
@@ -356,9 +356,9 @@ checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
 
 [[package]]
 name = "signal-hook-registry"
-version = "1.4.2"
+version = "1.4.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a9e9e0b4211b72e7b8b6e85c807d36c212bdb33ea8587f7569562a84df5465b1"
+checksum = "9203b8055f63a2a00e2f593bb0510367fe707d7ff1e5c872de2f537b339e5410"
 dependencies = [
  "libc",
 ]
@@ -374,15 +374,15 @@ dependencies = [
 
 [[package]]
 name = "smallvec"
-version = "1.14.0"
+version = "1.15.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7fcf8323ef1faaee30a44a340193b1ac6814fd9b7b4e88e9d4519a3e4abe1cfd"
+checksum = "8917285742e9f3e1683f0a9c4e6b57960b7314d0b08d30d1ecd426713ee2eee9"
 
 [[package]]
 name = "socket2"
-version = "0.5.8"
+version = "0.5.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c970269d99b64e60ec3bd6ad27270092a5394c4e309314b18ae3fe575695fbe8"
+checksum = "4f5fd57c80058a56cf5c777ab8a126398ece8e442983605d280a44ce79d0edef"
 dependencies = [
  "libc",
  "windows-sys 0.52.0",
@@ -396,9 +396,9 @@ checksum = "7da8b5736845d9f2fcb837ea5d9e2628564b3b043a70948a3f0b778838c5fb4f"
 
 [[package]]
 name = "syn"
-version = "2.0.99"
+version = "2.0.101"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e02e925281e18ffd9d640e234264753c43edc62d64b2d4cf898f1bc5e75f3fc2"
+checksum = "8ce2b7fc941b3a24138a0a7cf8e858bfc6a992e7978a068a5c760deb0ed43caf"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -407,9 +407,9 @@ dependencies = [
 
 [[package]]
 name = "tokio"
-version = "1.43.0"
+version = "1.45.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3d61fa4ffa3de412bfea335c6ecff681de2b609ba3c77ef3e00e521813a9ed9e"
+checksum = "2513ca694ef9ede0fb23fe71a4ee4107cb102b9dc1930f6d0fd77aae068ae165"
 dependencies = [
  "backtrace",
  "bytes",
@@ -454,9 +454,9 @@ checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
 
 [[package]]
 name = "which"
-version = "7.0.2"
+version = "7.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2774c861e1f072b3aadc02f8ba886c26ad6321567ecc294c935434cad06f1283"
+checksum = "24d643ce3fd3e5b54854602a080f34fb10ab75e0b813ee32d00ca2b44fa74762"
 dependencies = [
  "either",
  "env_home",
diff --git a/fastpool/Cargo.toml b/fastpool/Cargo.toml
index 6bb599b..fc16b53 100644
--- a/fastpool/Cargo.toml
+++ b/fastpool/Cargo.toml
@@ -26,7 +26,7 @@ repository.workspace = true
 rust-version.workspace = true
 
 [dependencies]
-mea = { version = "0.3.6" }
+mea = { version = "0.3.7" }
 scopeguard = { version = "1.2.0" }
 
 [dev-dependencies]
diff --git a/fastpool/src/bounded.rs b/fastpool/src/bounded.rs
index 115cbac..3e3e521 100644
--- a/fastpool/src/bounded.rs
+++ b/fastpool/src/bounded.rs
@@ -222,8 +222,18 @@ impl<M: ManageObject> Pool<M> {
                 return 0;
             }
 
-            // exclude idle objects that already exists
-            permit.release(idles);
+            match permit.split(idles) {
+                None => unreachable!(
+                    "idles ({}) should be less than permits ({})",
+                    idles,
+                    permit.permits()
+                ),
+                Some(p) => {
+                    // reduced by existing idle objects and release the corresponding permits
+                    drop(p);
+                }
+            }
+
             permit.permits()
         };
 
@@ -241,8 +251,13 @@ impl<M: ManageObject> Pool<M> {
                 replenished += 1;
             }
 
-            // always release one permit to unblock other waiters
-            permit.release(1);
+            match permit.split(1) {
+                None => unreachable!("permit must be greater than 0 at this point"),
+                Some(p) => {
+                    // always release one permit to unblock other waiters
+                    drop(p);
+                }
+            }
         }
 
         replenished
diff --git a/fastpool/tests/replenish_tests.rs b/fastpool/tests/replenish_tests.rs
index b35cd9a..0b2ddc6 100644
--- a/fastpool/tests/replenish_tests.rs
+++ b/fastpool/tests/replenish_tests.rs
@@ -21,7 +21,7 @@ use fastpool::bounded::Pool;
 use fastpool::bounded::PoolConfig;
 
 #[tokio::test]
-async fn test_simple_replenish() {
+async fn test_replenish() {
     #[derive(Default)]
     struct Manager;