Use borrows for the buffer when flagging a dirty line gives us

a 4.1% throughput improvement in the

Author: migueldeicaza

Sources/SwiftTerm/Terminal.swift

@@ -1008,7 +1008,7 @@ open class Terminal {
         let buffer = self.buffer
         readingBuffer.prepare(data)
 
-        updateRange (buffer.y)
+        updateRange(borrowing: buffer, buffer.y)
         while readingBuffer.hasNext() {
             var ch: Character = " "
             var chWidth: Int = 0
@@ -1165,7 +1165,7 @@ open class Terminal {
                                     }
                                 }
                                 existingLine [lastx] = cd
-                                updateRange (last.y)
+                                updateRange(borrowing: buffer, last.y)
                                 continue
                             }
                         }
@@ -1183,7 +1183,7 @@ open class Terminal {
             let charData = makeCharData (attribute: curAttr, char: ch, size: Int8 (chWidth))
             buffer.insertCharacter(charData)
         }
-        updateRange (buffer.y)
+        updateRange(borrowing: buffer, buffer.y)
         readingBuffer.done ()
     }
 
@@ -4605,7 +4605,31 @@ open class Terminal {
             }
         }
     }
-    
+
+    func updateRange (borrowing buffer: borrowing Buffer, _ y: Int, scrolling: Bool = false)
+    {
+        if !scrolling {
+            let effectiveY = buffer._yDisp + y
+            if effectiveY >= 0 {
+                if effectiveY < scrollInvariantRefreshStart {
+                    scrollInvariantRefreshStart = effectiveY
+                }
+                if effectiveY > scrollInvariantRefreshEnd {
+                    scrollInvariantRefreshEnd = effectiveY
+                }
+            }
+        }
+
+        if y >= 0 {
+            if y < refreshStart {
+                refreshStart = y
+            }
+            if y > refreshEnd {
+                refreshEnd = y
+            }
+        }
+    }
+
     func updateRange (startLine: Int, endLine: Int, scrolling: Bool = false)
     {
         updateRange (startLine, scrolling: scrolling)

Tests/SwiftTermTests/PerformanceTest.swift

@@ -77,6 +77,9 @@ final class PerformaceTests {
     }
 
     @Test func repeatBigBlob() {
+        // This file is generated with:
+        // vtebench:
+        // target/release/vtebench --max-samples 1 -b benchmarks/medium_cells/
         guard let d = try? Data(contentsOf: URL(filePath: "/Users/miguel/cvs/vtebench/x")) else {
             print("Skipping test, we do not have the data")
             return