Prevent apps with the same folder name from colliding (#270)

before this commit if two symlinks were targeting distinct folders having the same name the app were considered to be the same

cmd/puma-dev/main_test.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"crypto/sha1"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -237,8 +238,12 @@ func runPlatformAgnosticTestScenarios(t *testing.T) {
 			panic(err)
 		}
 
-		assert.NoError(t, pollForEvent(t, "rack-hi-puma", "killing_app", "restart.txt touched"))
-		assert.NoError(t, pollForEvent(t, "rack-hi-puma", "shutdown", ""))
+		appRoot := filepath.Join(ProjectRoot, "etc", "rack-hi-puma")
+		h := sha1.New()
+		h.Write([]byte(appRoot))
+		appName := fmt.Sprintf("rack-hi-puma-%.4x", h.Sum(nil))
+		assert.NoError(t, pollForEvent(t, appName, "killing_app", "restart.txt touched"))
+		assert.NoError(t, pollForEvent(t, appName, "shutdown", ""))
 	})
 
 	t.Run("unknown app", func(t *testing.T) {

dev/app.go

@@ -3,6 +3,7 @@ package dev
 import (
 	"bufio"
 	"bytes"
+	"crypto/sha1"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -514,8 +515,10 @@ func (a *AppPool) App(name string) (*App, error) {
 	destStat, err := os.Stat(destPath)
 	if err == nil {
 		destName := destStat.Name()
-		if destName != canonicalName {
-			canonicalName = destName
+		if destName != name {
+			h := sha1.New()
+			h.Write([]byte(destPath))
+			canonicalName = fmt.Sprintf("%s-%.4x", destStat.Name(), h.Sum(nil))
 			aliasName = name
 		}
 	}