GC avoidance and tmpDeterminstic (#570)

* GC avoidance and tmpDeterminstic

* change tmpDeterministic to use hashing

- temporaryDeterministic() now takes in a key and hashes it
- creates directory with the hash

* Update Sources/tart/VMStorageOCI.swift

Co-authored-by: Fedor Korotkov <fedor.korotkov@gmail.com>

---------

Co-authored-by: Fedor Korotkov <fedor.korotkov@gmail.com>

Sources/tart/Root.swift

@@ -81,10 +81,12 @@ struct Root: AsyncParsableCommand {
       var command = try parseAsRoot()
 
       // Run garbage-collection before each command (shouldn't take too long)
-      do {
-        try Config().gc()
-      } catch {
-        fputs("Failed to perform garbage collection!\n\(error)\n", stderr)
+      if type(of: command) != type(of: Pull()) && type(of: command) != type(of: Clone()){
+        do {
+          try Config().gc()
+        } catch {
+          fputs("Failed to perform garbage collection!\n\(error)\n", stderr)
+        }
       }
 
       if var asyncCommand = command as? AsyncParsableCommand {

Sources/tart/VMDirectory.swift

@@ -1,5 +1,6 @@
 import Foundation
 import Virtualization
+import CryptoKit
 
 struct VMDirectory: Prunable {
   var baseURL: URL
@@ -59,6 +60,17 @@ struct VMDirectory: Prunable {
     return VMDirectory(baseURL: tmpDir)
   }
 
+  //Create tmp directory with hashing
+  static func temporaryDeterministic(key: String) throws -> VMDirectory {
+    let keyData = Data(key.utf8)
+    let hash = Insecure.MD5.hash(data: keyData)
+    // Convert hash to string
+    let hashString = hash.compactMap { String(format: "%02x", $0) }.joined()
+    let tmpDir = try Config().tartTmpDir.appendingPathComponent(hashString)
+    try FileManager.default.createDirectory(at: tmpDir, withIntermediateDirectories: true)
+    return VMDirectory(baseURL: tmpDir)
+  }
+
   var initialized: Bool {
     FileManager.default.fileExists(atPath: configURL.path) &&
       FileManager.default.fileExists(atPath: diskURL.path) &&

Sources/tart/VMStorageOCI.swift

@@ -170,7 +170,7 @@ class VMStorageOCI: PrunableStorage {
 
     if !exists(digestName) {
       let transaction = SentrySDK.startTransaction(name: name.description, operation: "pull", bindToScope: true)
-      let tmpVMDir = try VMDirectory.temporary()
+      let tmpVMDir = try VMDirectory.temporaryDeterministic(key: name.description)
 
       // Lock the temporary VM directory to prevent it's garbage collection
       let tmpVMDirLock = try FileLock(lockURL: tmpVMDir.baseURL)