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replace some utils.Semaphore with (*sync.Mutex).TryLock

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See #1994
This commit is contained in:
Shivaram Lingamneni 2022-09-02 04:00:38 -04:00
parent 531a1d6864
commit 746309e386
3 changed files with 39 additions and 46 deletions
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19
irc/socket.go
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@ -8,8 +8,6 @@ import (
"errors"
"io"
"sync"
"github.com/ergochat/ergo/irc/utils"
)
var (
@ -27,7 +25,7 @@ type Socket struct {
maxSendQBytes int
// this is a trylock enforcing that only one goroutine can write to `conn` at a time
writerSemaphore utils.Semaphore
writeLock sync.Mutex
buffers [][]byte
totalLength int
@ -40,9 +38,8 @@ type Socket struct {
// NewSocket returns a new Socket.
func NewSocket(conn IRCConn, maxSendQBytes int) *Socket {
result := Socket{
conn: conn,
maxSendQBytes: maxSendQBytes,
writerSemaphore: utils.NewSemaphore(1),
conn: conn,
maxSendQBytes: maxSendQBytes,
}
return &result
}
@ -128,8 +125,8 @@ func (socket *Socket) BlockingWrite(data []byte) (err error) {
}()
// blocking acquire of the trylock
socket.writerSemaphore.Acquire()
defer socket.writerSemaphore.Release()
socket.writeLock.Lock()
defer socket.writeLock.Unlock()
// first, flush any buffered data, to preserve the ordering guarantees
closed := socket.performWrite()
@ -146,7 +143,7 @@ func (socket *Socket) BlockingWrite(data []byte) (err error) {
// wakeWriter starts the goroutine that actually performs the write, without blocking
func (socket *Socket) wakeWriter() {
if socket.writerSemaphore.TryAcquire() {
if socket.writeLock.TryLock() {
// acquired the trylock; send() will release it
go socket.send()
}
@ -182,12 +179,12 @@ func (socket *Socket) send() {
socket.performWrite()
// surrender the trylock, avoiding a race where a write comes in after we've
// checked readyToWrite() and it returned false, but while we still hold the trylock:
socket.writerSemaphore.Release()
socket.writeLock.Unlock()
// check if more data came in while we held the trylock:
if !socket.readyToWrite() {
return
}
if !socket.writerSemaphore.TryAcquire() {
if !socket.writeLock.TryLock() {
// failed to acquire; exit and wait for the holder to observe readyToWrite()
// after releasing it
return