From 1227fa7a04bec9d3d6b3260f79b7dacf33b35842 Mon Sep 17 00:00:00 2001
From: Nuno Cruces <ncruces@users.noreply.github.com>
Date: Fri, 13 Dec 2024 16:04:37 +0000
Subject: [PATCH] Skip sleeping if blocked.

---
 conn.go         | 14 +++++++++-----
 vfs/os_linux.go | 16 +---------------
 2 files changed, 10 insertions(+), 20 deletions(-)

diff --git a/conn.go b/conn.go
index 45c294bb..d1ce3055 100644
--- a/conn.go
+++ b/conn.go
@@ -36,7 +36,8 @@ type Conn struct {
 	rollback   func()
 	arena      arena
 
-	kickoff time.Time
+	busy1st time.Time
+	busylst time.Time
 	handle  uint32
 }
 
@@ -394,12 +395,15 @@ func timeoutCallback(ctx context.Context, mod api.Module, count, tmout int32) (r
 	if c, ok := ctx.Value(connKey{}).(*Conn); ok && c.interrupt.Err() == nil {
 		switch {
 		case count == 0:
-			c.kickoff = time.Now()
-		case time.Since(c.kickoff) >= time.Duration(tmout)*time.Millisecond:
+			c.busy1st = time.Now()
+		case time.Since(c.busy1st) >= time.Duration(tmout)*time.Millisecond:
 			return 0
 		}
-		const sleepIncrement = 4*1024*1024 - 1 // power of two, ~4ms
-		time.Sleep(time.Duration(rand.Int63() & sleepIncrement))
+		if time.Since(c.busylst) < time.Millisecond {
+			const sleepIncrement = 2*1024*1024 - 1 // power of two, ~2ms
+			time.Sleep(time.Duration(rand.Int63() & sleepIncrement))
+		}
+		c.busylst = time.Now()
 		return 1
 	}
 	return 0
diff --git a/vfs/os_linux.go b/vfs/os_linux.go
index 0db6b276..6199c7b0 100644
--- a/vfs/os_linux.go
+++ b/vfs/os_linux.go
@@ -3,7 +3,6 @@
 package vfs
 
 import (
-	"math/rand"
 	"os"
 	"time"
 
@@ -38,23 +37,10 @@ func osLock(file *os.File, typ int16, start, len int64, timeout time.Duration, d
 	}
 	var err error
 	switch {
-	case timeout == 0:
-		err = unix.FcntlFlock(file.Fd(), unix.F_OFD_SETLK, &lock)
 	case timeout < 0:
 		err = unix.FcntlFlock(file.Fd(), unix.F_OFD_SETLKW, &lock)
 	default:
-		before := time.Now()
-		for {
-			err = unix.FcntlFlock(file.Fd(), unix.F_OFD_SETLK, &lock)
-			if errno, _ := err.(unix.Errno); errno != unix.EAGAIN {
-				break
-			}
-			if time.Since(before) > timeout {
-				break
-			}
-			const sleepIncrement = 1024*1024 - 1 // power of two, ~1ms
-			time.Sleep(time.Duration(rand.Int63() & sleepIncrement))
-		}
+		err = unix.FcntlFlock(file.Fd(), unix.F_OFD_SETLK, &lock)
 	}
 	return osLockErrorCode(err, def)
 }