From c67efb88f3600b9a4f4784bd156c8ac15c3a8a93 Mon Sep 17 00:00:00 2001
From: Nikolay Edigaryev <edigaryev@gmail.com>
Date: Fri, 14 Oct 2022 01:43:37 +0400
Subject: [PATCH] Fix tart prune --cache-budget logic (#272)

---
 Sources/tart/Commands/Prune.swift | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/Sources/tart/Commands/Prune.swift b/Sources/tart/Commands/Prune.swift
index 4836c7c..8b978e9 100644
--- a/Sources/tart/Commands/Prune.swift
+++ b/Sources/tart/Commands/Prune.swift
@@ -63,21 +63,25 @@ struct Prune: AsyncParsableCommand {
     let prunableStorages: [PrunableStorage] = [VMStorageOCI(), try IPSWCache()]
     let prunables: [Prunable] = try prunableStorages
             .flatMap { try $0.prunables() }
-            .sorted { try $0.accessDate() < $1.accessDate() }
+            .sorted { try $0.accessDate() > $1.accessDate() }
 
-    let cacheUsedBytes = try prunables.map { try $0.sizeBytes() }.reduce(0, +)
-    var cacheReclaimedBytes: Int = 0
+    var cacheBudgetBytes = cacheBudgetBytes
+    var prunablesToDelete: [Prunable] = []
 
-    var it = prunables.makeIterator()
+    for prunable in prunables {
+      let prunableSizeBytes = UInt64(try prunable.sizeBytes())
 
-    while (cacheUsedBytes - cacheReclaimedBytes) > cacheBudgetBytes {
-      guard let prunable = it.next() else {
-        break
+      if prunableSizeBytes <= cacheBudgetBytes {
+        // Don't mark for deletion as
+        // there's a budget available
+        cacheBudgetBytes -= prunableSizeBytes
+      } else {
+        // Mark for deletion
+        prunablesToDelete.append(prunable)
       }
-
-      cacheReclaimedBytes -= try prunable.sizeBytes()
-      try prunable.delete()
     }
+
+    try prunablesToDelete.forEach { try $0.delete() }
   }
 
   static func pruneReclaim(reclaimBytes: UInt64) throws {