From b931868863003f7998eed5dfe2274dca5d21c292 Mon Sep 17 00:00:00 2001
From: zjx158094 <zjx158094@alibaba-inc.com>
Date: Fri, 17 Sep 2021 20:11:56 +0800
Subject: [PATCH] introducing cbList to replace list.List

---
 aio_generic.go |  4 +---
 cblist.go      | 20 ++++++++++++++++++++
 watcher.go     | 43 +++++++++++++++++++------------------------
 3 files changed, 40 insertions(+), 27 deletions(-)
 create mode 100644 cblist.go

diff --git a/aio_generic.go b/aio_generic.go
index 6a4b924..e8ce065 100644
--- a/aio_generic.go
+++ b/aio_generic.go
@@ -1,7 +1,6 @@
 package gaio
 
 import (
-	"container/list"
 	"errors"
 	"net"
 	"time"
@@ -110,8 +109,7 @@ type OpResult struct {
 
 // aiocb contains all info for a single request
 type aiocb struct {
-	l          *list.List // list where this request belongs to
-	elem       *list.Element
+	l          *cbList // list where this request belongs to
 	ctx        interface{} // user context associated with this request
 	ptr        uintptr     // pointer to conn
 	op         OpType      // read or write
diff --git a/cblist.go b/cblist.go
new file mode 100644
index 0000000..211ce20
--- /dev/null
+++ b/cblist.go
@@ -0,0 +1,20 @@
+package gaio
+
+type cbList []*aiocb
+
+func (l *cbList) PushBack(cb *aiocb) {
+	*l = append(*l, cb)
+}
+
+func (l *cbList) Remove(cb *aiocb) {
+	for idx, v := range *l {
+		if v == cb {
+			*l = append((*l)[:idx], (*l)[idx+1:]...)
+			return
+		}
+	}
+}
+
+func (l *cbList) RemoveHeadN(n int) {
+	*l = append((*l)[:0], (*l)[n:]...)
+}
diff --git a/watcher.go b/watcher.go
index 6c04ed7..95202c2 100644
--- a/watcher.go
+++ b/watcher.go
@@ -8,7 +8,6 @@ package gaio
 
 import (
 	"container/heap"
-	"container/list"
 	"io"
 	"net"
 	"reflect"
@@ -31,8 +30,8 @@ func init() {
 
 // fdDesc contains all data structures associated to fd
 type fdDesc struct {
-	readers list.List // all read/write requests
-	writers list.List
+	readers cbList // all read/write requests
+	writers cbList
 	ptr     uintptr // pointer to net.Conn
 	r_armed bool
 	w_armed bool
@@ -385,15 +384,13 @@ func (w *watcher) tryWrite(fd int, pcb *aiocb) bool {
 func (w *watcher) releaseConn(ident int) {
 	if desc, ok := w.descs[ident]; ok {
 		// delete from heap
-		for e := desc.readers.Front(); e != nil; e = e.Next() {
-			tcb := e.Value.(*aiocb)
+		for _, tcb := range desc.readers {
 			// notify caller
 			tcb.err = io.ErrClosedPipe
 			w.deliver(tcb)
 		}
 
-		for e := desc.writers.Front(); e != nil; e = e.Next() {
-			tcb := e.Value.(*aiocb)
+		for _, tcb := range desc.writers {
 			tcb.err = io.ErrClosedPipe
 			w.deliver(tcb)
 		}
@@ -447,7 +444,7 @@ func (w *watcher) loop() {
 					// ErrDeadline
 					pcb.err = ErrDeadline
 					// remove from list
-					pcb.l.Remove(pcb.elem)
+					pcb.l.Remove(pcb)
 					w.deliver(pcb)
 				} else {
 					w.timer.Reset(pcb.deadline.Sub(now))
@@ -538,7 +535,7 @@ func (w *watcher) handlePending(pending []*aiocb) {
 		switch pcb.op {
 		case OpRead:
 			// try immediately queue is empty
-			if desc.readers.Len() == 0 {
+			if len(desc.readers) == 0 {
 				if w.tryRead(ident, pcb) {
 					w.deliver(pcb)
 					continue
@@ -546,13 +543,13 @@ func (w *watcher) handlePending(pending []*aiocb) {
 			}
 			// enqueue for poller events
 			pcb.l = &desc.readers
-			pcb.elem = pcb.l.PushBack(pcb)
+			pcb.l.PushBack(pcb)
 
 			if !desc.r_armed {
 				desc.r_armed = true
 			}
 		case OpWrite:
-			if desc.writers.Len() == 0 {
+			if len(desc.writers) == 0 {
 				if w.tryWrite(ident, pcb) {
 					w.deliver(pcb)
 					continue
@@ -560,7 +557,7 @@ func (w *watcher) handlePending(pending []*aiocb) {
 			}
 
 			pcb.l = &desc.writers
-			pcb.elem = pcb.l.PushBack(pcb)
+			pcb.l.PushBack(pcb)
 
 			if !desc.w_armed {
 				desc.w_armed = true
@@ -595,38 +592,36 @@ func (w *watcher) handleEvents(pe pollerEvents) {
 		if desc, ok := w.descs[e.ident]; ok {
 			if e.ev&EV_READ != 0 {
 				desc.r_armed = false
-				var next *list.Element
-				for elem := desc.readers.Front(); elem != nil; elem = next {
-					next = elem.Next()
-					pcb := elem.Value.(*aiocb)
+				count := 0
+				for _, pcb := range desc.readers {
 					if w.tryRead(e.ident, pcb) {
 						w.deliver(pcb)
-						desc.readers.Remove(elem)
+						count++
 					} else {
 						break
 					}
 				}
+				desc.readers.RemoveHeadN(count)
 
-				if desc.readers.Len() > 0 {
+				if len(desc.readers) > 0 {
 					desc.r_armed = true
 				}
 			}
 
 			if e.ev&EV_WRITE != 0 {
 				desc.w_armed = false
-				var next *list.Element
-				for elem := desc.writers.Front(); elem != nil; elem = next {
-					next = elem.Next()
-					pcb := elem.Value.(*aiocb)
+				count := 0
+				for _, pcb := range desc.writers {
 					if w.tryWrite(e.ident, pcb) {
 						w.deliver(pcb)
-						desc.writers.Remove(elem)
+						count++
 					} else {
 						break
 					}
 				}
+				desc.writers.RemoveHeadN(count)
 
-				if desc.writers.Len() > 0 {
+				if len(desc.writers) > 0 {
 					desc.w_armed = true
 				}
 			}