From d28e60d19f9315a494f6d252f19698420f2823a1 Mon Sep 17 00:00:00 2001
From: NiseVoid <nisevoid@gmail.com>
Date: Thu, 6 Aug 2020 11:41:26 +0200
Subject: [PATCH] Initial commit

---
 waitfor.go      | 25 +++++++++++++++++++++
 waitfor_test.go | 58 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 83 insertions(+)
 create mode 100644 waitfor.go
 create mode 100644 waitfor_test.go

diff --git a/waitfor.go b/waitfor.go
new file mode 100644
index 0000000..d9f6410
--- /dev/null
+++ b/waitfor.go
@@ -0,0 +1,25 @@
+package waitfor
+
+import (
+	"net"
+	"time"
+)
+
+func Try(network, address string, interval, limit time.Duration) bool {
+	start := time.Now()
+	for {
+		if limit >= 0 && time.Since(start) > limit {
+			return false
+		}
+
+		attempt := time.Now()
+		conn, err := net.DialTimeout(network, address, interval)
+		if err != nil {
+			time.Sleep(time.Until(attempt.Add(interval)))
+			continue
+		}
+
+		conn.Close()
+		return true
+	}
+}
diff --git a/waitfor_test.go b/waitfor_test.go
new file mode 100644
index 0000000..4094728
--- /dev/null
+++ b/waitfor_test.go
@@ -0,0 +1,58 @@
+package waitfor
+
+import (
+	"net"
+	"testing"
+	"time"
+
+	"git.fuyu.moe/Fuyu/assert"
+)
+
+func TestDeadline(t *testing.T) {
+	assert := assert.New(t)
+
+	start := time.Now()
+	ok := Try(`tcp`, `127.0.0.1:65398`, time.Microsecond*100, time.Millisecond)
+
+	assert.False(ok)
+	assert.Eq(int64(1), time.Since(start).Milliseconds())
+
+	start = time.Now()
+	ok = Try(`tcp`, `127.0.0.1:65398`, time.Microsecond*100, 0)
+
+	assert.False(ok)
+	assert.Eq(int64(0), time.Since(start).Milliseconds())
+}
+
+func TestSuccess(t *testing.T) {
+	assert := assert.New(t)
+
+	conn, err := net.Listen(`tcp`, `127.0.0.1:65398`)
+	assert.NoError(err)
+	defer conn.Close()
+
+	start := time.Now()
+	ok := Try(`tcp`, `127.0.0.1:65398`, time.Microsecond*100, time.Millisecond*10)
+
+	assert.True(ok)
+	assert.True(time.Since(start).Milliseconds() < 10)
+}
+
+func TestInfiniteLimit(t *testing.T) {
+	assert := assert.New(t)
+
+	var conn net.Listener
+	go func() {
+		time.Sleep(time.Millisecond)
+		var err error
+		conn, err = net.Listen(`tcp`, `127.0.0.1:65398`)
+		assert.NoError(err)
+	}()
+
+	start := time.Now()
+	ok := Try(`tcp`, `127.0.0.1:65398`, time.Microsecond*100, time.Millisecond*-1)
+
+	assert.True(ok)
+	assert.True(time.Since(start).Milliseconds() < 2)
+	conn.Close()
+}