Fix conditional cache updates on Windows filesystems

okhttp/src/commonJvmAndroid/kotlin/okhttp3/Cache.kt

@@ -263,7 +263,7 @@ class Cache internal constructor(
     val snapshot = (cached.body as CacheResponseBody).snapshot
     var editor: DiskLruCache.Editor? = null
     try {
-      editor = snapshot.edit() ?: return // edit() returns null if snapshot is not current.
+      editor = snapshot.editMetadata() ?: return // editMetadata() returns null if snapshot is not current.
       entry.writeTo(editor)
       editor.commit()
     } catch (_: IOException) {

okhttp/src/commonJvmAndroid/kotlin/okhttp3/internal/cache/DiskLruCache.kt

@@ -479,6 +479,14 @@ class DiskLruCache(
   fun edit(
     key: String,
     expectedSequenceNumber: Long = ANY_SEQUENCE_NUMBER,
+  ): Editor? = edit(key, expectedSequenceNumber, allowSourceLocks = false)
+
+  @Synchronized
+  @Throws(IOException::class)
+  private fun edit(
+    key: String,
+    expectedSequenceNumber: Long,
+    allowSourceLocks: Boolean,
   ): Editor? {
     initialize()
 
@@ -495,7 +503,7 @@ class DiskLruCache(
       return null // Another edit is in progress.
     }
 
-    if (entry != null && entry.lockingSourceCount != 0) {
+    if (!allowSourceLocks && entry != null && entry.lockingSourceCount != 0) {
       return null // We can't write this file because a reader is still reading it.
     }
 
@@ -855,6 +863,9 @@ class DiskLruCache(
     @Throws(IOException::class)
     fun edit(): Editor? = this@DiskLruCache.edit(key, sequenceNumber)
 
+    @Throws(IOException::class)
+    internal fun editMetadata(): Editor? = this@DiskLruCache.edit(key, sequenceNumber, allowSourceLocks = true)
+
     /** Returns the unbuffered stream with the value for [index]. */
     fun getSource(index: Int): Source = sources[index]
 

okhttp/src/jvmTest/kotlin/okhttp3/CacheTest.kt

@@ -3138,6 +3138,16 @@ class CacheTest {
 
   @Test
   fun conditionalHitUpdatesCache() {
+    assertConditionalHitUpdatesCache()
+  }
+
+  @Test
+  fun conditionalHitUpdatesCacheOnWindowsFileSystem() {
+    fileSystem.emulateWindows()
+    assertConditionalHitUpdatesCache()
+  }
+
+  private fun assertConditionalHitUpdatesCache() {
     server.enqueue(
       MockResponse
         .Builder()