Change to discardOldestFileIfNeeded sorting

CHANGELOG.md

@@ -7,6 +7,9 @@
 * Allow the metadata in `leaveBreadcrumb` to be null rather than enforcing non-null, aligning `bugsnag-android` with our other SDKs
   [#2180](https://github.com/bugsnag/bugsnag-android/pull/2180)
 
+* Added deterministic sorting for `discardOldestFileIfNeeded` method to avoid potential crashes where mutliple files have the same last modified time
+  [#2181](https://github.com/bugsnag/bugsnag-android/pull/2189)
+
 ## 6.13.0 (2025-04-15)
 
 ### Enhancements

bugsnag-android-core/src/main/java/com/bugsnag/android/FileStore.kt

@@ -114,10 +114,21 @@ internal abstract class FileStore(
         if (isStorageDirValid(storageDir)) {
             val listFiles = storageDir.listFiles() ?: return
             if (listFiles.size < maxStoreCount) return
-            val sortedListFiles = listFiles.sortedBy { it.lastModified() }
+
+            // Store lastModified to ensure it doesn't change between sorting
+            val fileMeta = listFiles.map { file ->
+                FileWithTimestamp(file, file.lastModified())
+            }
+
+            // Sort by cached lastModified timesstamps
+            val sortedListFiles = fileMeta
+                .sorted()
+                .map(FileWithTimestamp::file)
+
             // Number of files to discard takes into account that a new file may need to be written
             val numberToDiscard = listFiles.size - maxStoreCount + 1
             var discardedCount = 0
+
             for (file in sortedListFiles) {
                 if (discardedCount == numberToDiscard) {
                     return
@@ -188,3 +199,15 @@ internal abstract class FileStore(
         }
     }
 }
+
+/**
+ * A data holder for associating a {@link File} with its last modified timestamp.
+ *
+ * @param file The file to associate with a timestamp.
+ * @param timestamp The last modified time of the file, cached to ensure consistent ordering.
+ */
+private data class FileWithTimestamp(val file: File, val timestamp: Long) : Comparable<FileWithTimestamp> {
+    override fun compareTo(other: FileWithTimestamp): Int {
+        return timestamp.compareTo(other.timestamp)
+    }
+}