Rework

okhttp/src/main/kotlin/okhttp3/internal/cache/CacheLock.kt

@@ -1,3 +1,18 @@
+/*
+ * Copyright (C) 2023 Block, Inc.
+ *
+ * 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 okhttp3.internal.cache
 
 import android.annotation.SuppressLint
@@ -7,14 +22,15 @@ import java.nio.file.StandardOpenOption
 import java.util.Collections
 import okhttp3.internal.platform.Platform
 import okio.FileSystem
+import okio.IOException
 import okio.Path
 
 internal object CacheLock {
   private val openCaches = Collections.synchronizedMap(mutableMapOf<Path, Exception>())
 
   fun openLock(fileSystem: FileSystem, directory: Path): Closeable {
     return if (fileSystem == FileSystem.SYSTEM && !Platform.isAndroid) {
-      fileSystemLock(directory)
+      fileSystemLock(inMemoryLock(directory), directory)
     } else {
       inMemoryLock(directory)
     }
@@ -33,11 +49,15 @@ internal object CacheLock {
   }
 
   @SuppressLint("NewApi")
-  fun fileSystemLock(directory: Path): Closeable {
+  fun fileSystemLock(memoryLock: Closeable, directory: Path): Closeable {
     val lockFile = directory / "lock"
+    lockFile.toFile().createNewFile()
     val channel = FileChannel.open(lockFile.toNioPath(), StandardOpenOption.APPEND)
 
+    channel.tryLock() ?: throw IOException("Cache $directory is locked by another process")
+
     return okio.Closeable {
+      memoryLock.close()
       channel.close()
     }
   }