From 1a02c374ce329e47a6c83bd6cf6f9d796682460a Mon Sep 17 00:00:00 2001
From: Dima Krasner <dima@dimakrasner.com>
Date: Wed, 25 Dec 2024 17:13:01 +0200
Subject: [PATCH] drop the golang.org/x/sync/semaphore dependency

---
 fed/resolve.go      | 12 ++++++------
 fed/resolve_test.go |  2 +-
 go.mod              |  1 -
 go.sum              |  2 --
 lock/lock.go        | 42 ++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 49 insertions(+), 10 deletions(-)
 create mode 100644 lock/lock.go

diff --git a/fed/resolve.go b/fed/resolve.go
index ff2cc8d6..5e7b8090 100644
--- a/fed/resolve.go
+++ b/fed/resolve.go
@@ -26,7 +26,7 @@ import (
 	"github.com/dimkr/tootik/cfg"
 	"github.com/dimkr/tootik/data"
 	"github.com/dimkr/tootik/httpsig"
-	"golang.org/x/sync/semaphore"
+	"github.com/dimkr/tootik/lock"
 	"hash/crc32"
 	"io"
 	"log/slog"
@@ -53,7 +53,7 @@ type Resolver struct {
 	sender
 	BlockedDomains *BlockList
 	db             *sql.DB
-	locks          []*semaphore.Weighted
+	locks          []lock.Lock
 }
 
 var (
@@ -78,10 +78,10 @@ func NewResolver(blockedDomains *BlockList, domain string, cfg *cfg.Config, clie
 		},
 		BlockedDomains: blockedDomains,
 		db:             db,
-		locks:          make([]*semaphore.Weighted, cfg.MaxResolverRequests),
+		locks:          make([]lock.Lock, cfg.MaxResolverRequests),
 	}
 	for i := 0; i < len(r.locks); i++ {
-		r.locks[i] = semaphore.NewWeighted(1)
+		r.locks[i] = lock.New()
 	}
 
 	return &r
@@ -190,10 +190,10 @@ func (r *Resolver) tryResolve(ctx context.Context, key httpsig.Key, host, name s
 
 	if !isLocal && flags&ap.Offline == 0 {
 		lock := r.locks[crc32.ChecksumIEEE([]byte(host+name))%uint32(len(r.locks))]
-		if err := lock.Acquire(ctx, 1); err != nil {
+		if err := lock.Lock(ctx); err != nil {
 			return nil, nil, err
 		}
-		defer lock.Release(1)
+		defer lock.Unlock()
 	}
 
 	var tmp ap.Actor
diff --git a/fed/resolve_test.go b/fed/resolve_test.go
index 22ea4b05..6683d904 100644
--- a/fed/resolve_test.go
+++ b/fed/resolve_test.go
@@ -536,7 +536,7 @@ func TestResolve_FederatedActorFirstTimeCancelled(t *testing.T) {
 	resolver := NewResolver(&blockList, "localhost.localdomain", &cfg, &client, db)
 
 	for i := range resolver.locks {
-		assert.NoError(resolver.locks[i].Acquire(context.Background(), 1))
+		assert.NoError(resolver.locks[i].Lock(context.Background()))
 	}
 
 	ctx, cancel := context.WithCancel(context.Background())
diff --git a/go.mod b/go.mod
index 01a34b3f..4bf3ce8c 100644
--- a/go.mod
+++ b/go.mod
@@ -7,7 +7,6 @@ require (
 	github.com/mattn/go-sqlite3 v1.14.24
 	github.com/stretchr/testify v1.10.0
 	golang.org/x/image v0.23.0
-	golang.org/x/sync v0.10.0
 )
 
 require (
diff --git a/go.sum b/go.sum
index c8b437aa..0644a40a 100644
--- a/go.sum
+++ b/go.sum
@@ -10,8 +10,6 @@ github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOf
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 golang.org/x/image v0.23.0 h1:HseQ7c2OpPKTPVzNjG5fwJsOTCiiwS4QdsYi5XU6H68=
 golang.org/x/image v0.23.0/go.mod h1:wJJBTdLfCCf3tiHa1fNxpZmUI4mmoZvwMCPP0ddoNKY=
-golang.org/x/sync v0.10.0 h1:3NQrjDixjgGwUOCaF8w2+VYHv0Ve/vGYSbdkTa98gmQ=
-golang.org/x/sync v0.10.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
 golang.org/x/sys v0.15.0 h1:h48lPFYpsTvQJZF4EKyI4aLHaev3CxivZmv7yZig9pc=
 golang.org/x/sys v0.15.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
diff --git a/lock/lock.go b/lock/lock.go
new file mode 100644
index 00000000..3fae73ee
--- /dev/null
+++ b/lock/lock.go
@@ -0,0 +1,42 @@
+/*
+Copyright 2024 Dima Krasner
+
+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.
+*/
+
+// Package lock provides synchronization primitives.
+package lock
+
+import "context"
+
+// Lock is similar to [sync.Mutex] but locking is cancellable through a [context.Context].
+type Lock chan struct{}
+
+func New() Lock {
+	c := make(chan struct{}, 1)
+	c <- struct{}{}
+	return c
+}
+
+func (l Lock) Lock(ctx context.Context) error {
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case <-l:
+		return nil
+	}
+}
+
+func (l Lock) Unlock() {
+	l <- struct{}{}
+}