Add some notes

README.org

@@ -1,6 +1,7 @@
 #+title: Calkin-Wilf trees
 #+author: Aryadev Chavali
 #+date: 2024-07-27
+#+filetags: cpp cw_tree
 
 A graphical visualisation of
 [[https://en.wikipedia.org/wiki/Calkin%E2%80%93Wilf_tree][Calkin-Wilf
@@ -19,12 +20,30 @@ This was done just for fun really, but it's quite fun to see it
 generate a dense number line over many iterations.
 * TODOs
 ** TODO Multithreading
+SCHEDULED: <2025-11-18 Tue>
 Currently single threaded.  A multithreaded implementation could have
 multiple nodes generated at once, which would speed up the
 implementation.
 
 Might need to study my current implementation to see if it could be
 done better.
+
+2025-11-17: Notes:
+- Mutex on the queue [[file:src/main.cpp::std::queue<word_t>
+  iteration_queue;][the queue]] and the allocator will be necessary.
+- Perhaps we could do two mutexes, one per structure?
+- We'd need to lock for [[file:src/numerics.cpp::std::tuple<Fraction,
+  Fraction, Fraction> iterate(std::queue<word_t> &queue,][iterate]]
+- Locking scheme could be:
+  - Lock queue when popping a value as root, then unlock.
+  - Leave queue and allocator unlocked while getting root/left/right
+    values (readonly) and computing (but not setting/allocating) the
+    left and right node values
+  - Allocator Lock when allocating the left/right values, setting the
+    root's left and right, then unlock.
+  - Queue lock when pushing the left and right fractions for further
+    processing, then unlock
+  - Unlock all when returning relevant values
 ** TODO Prettify code base
 It's a big blob of code currently in the graphics portion.  Not very
 pretty but it gets the job done.  Try modularisation.

src/main.cpp

@@ -33,7 +33,7 @@
 #define LINE_TOP    (7 * HEIGHT / 16)
 #define LINE_BOTTOM (9 * HEIGHT / 16)
 
-std::pair<std::string, int> get_fraction_drawable(Fraction f)
+std::pair<std::string, int> fraction_to_string(Fraction f)
 {
   std::string s{to_string(f)};
   int width = MeasureText(s.c_str(), FONT_SIZE);
@@ -44,7 +44,7 @@ void draw_fraction(Fraction f, word_t x, word_t y)
 {
   std::string s;
   int width;
-  std::tie(s, width) = get_fraction_drawable(f);
+  std::tie(s, width) = fraction_to_string(f);
   // Centered at (x, y)
   DrawText(s.c_str(), x - width / 2, y - FONT_SIZE, FONT_SIZE, WHITE);
 }