From 20aa85037dfa15f45d16e1a91c13f80dfb10a91f Mon Sep 17 00:00:00 2001
From: Nedyalko Dyakov <nedyalko.dyakov@gmail.com>
Date: Mon, 10 Nov 2025 16:22:56 +0200
Subject: [PATCH] address linter and tests

---
 internal/pool/conn_state.go | 23 +++++++++++++----------
 internal/semaphore.go       |  6 ------
 2 files changed, 13 insertions(+), 16 deletions(-)

diff --git a/internal/pool/conn_state.go b/internal/pool/conn_state.go
index a3c3a57f..2050a742 100644
--- a/internal/pool/conn_state.go
+++ b/internal/pool/conn_state.go
@@ -218,17 +218,20 @@ func (sm *ConnStateMachine) AwaitAndTransition(
 	targetState ConnState,
 ) (ConnState, error) {
 	// Fast path: try immediate transition with CAS to prevent race conditions
-	for _, fromState := range validFromStates {
-		// Check if we're already in target state
-		if fromState == targetState && sm.GetState() == targetState {
-			return targetState, nil
-		}
+	// BUT: only if there are no waiters in the queue (to maintain FIFO ordering)
+	if sm.waiterCount.Load() == 0 {
+		for _, fromState := range validFromStates {
+			// Check if we're already in target state
+			if fromState == targetState && sm.GetState() == targetState {
+				return targetState, nil
+			}
 
-		// Try to atomically swap from fromState to targetState
-		if sm.state.CompareAndSwap(uint32(fromState), uint32(targetState)) {
-			// Success! We transitioned atomically
-			sm.notifyWaiters()
-			return targetState, nil
+			// Try to atomically swap from fromState to targetState
+			if sm.state.CompareAndSwap(uint32(fromState), uint32(targetState)) {
+				// Success! We transitioned atomically
+				sm.notifyWaiters()
+				return targetState, nil
+			}
 		}
 	}
 
diff --git a/internal/semaphore.go b/internal/semaphore.go
index 4c681482..a1dfca5f 100644
--- a/internal/semaphore.go
+++ b/internal/semaphore.go
@@ -14,12 +14,6 @@ var semTimers = sync.Pool{
 	},
 }
 
-// waiter represents a goroutine waiting for a token.
-type waiter struct {
-	ready chan struct{}
-	next  *waiter
-}
-
 // FastSemaphore is a channel-based semaphore optimized for performance.
 // It uses a fast path that avoids timer allocation when tokens are available.
 // The channel is pre-filled with tokens: Acquire = receive, Release = send.