From 024468cdddaa716b8c549af729dfd17c812a1c47 Mon Sep 17 00:00:00 2001
From: Peter Tang <petersktang@gmail.com>
Date: Mon, 18 Sep 2023 21:54:45 +0800
Subject: [PATCH] threadsafe protect CTFontCreateWithGraphicsFont

---
 Sources/SwiftMath/MathBundle/MathFont.swift | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/Sources/SwiftMath/MathBundle/MathFont.swift b/Sources/SwiftMath/MathBundle/MathFont.swift
index 0b509cd..4bfd2b4 100644
--- a/Sources/SwiftMath/MathBundle/MathFont.swift
+++ b/Sources/SwiftMath/MathBundle/MathFont.swift
@@ -156,11 +156,15 @@ private class BundleManager {
         }
         //Note: ctfont creation and caching is now threadsafe.
         guard threadSafeQueue.sync(execute: { ctFonts[fontSizePair] }) == nil else { return ctFonts[fontSizePair]! }
-        let newCTFont = CTFontCreateWithGraphicsFont(cgFont, size, nil, nil)
-        threadSafeQueue.sync(flags: .barrier) {
-            ctFonts[fontSizePair] = newCTFont
-        }
-        return newCTFont
+        return threadSafeQueue.sync(flags: .barrier, execute: {
+            if let ctfont = ctFonts[fontSizePair] {
+                return ctfont
+            } else {
+                let result = CTFontCreateWithGraphicsFont(cgFont, size, nil, nil)
+                ctFonts[fontSizePair] = result
+                return result
+            }
+        })
     }
     fileprivate func obtainRawMathTable(font: MathFont) -> NSDictionary {
         onDemandRegistration(mathFont: font)