From d9089c4348ce69c2bbb61c162e4ee4a3a90c1db5 Mon Sep 17 00:00:00 2001
From: PowerUser64 <blake@blakenorth.net>
Date: Tue, 19 Nov 2024 15:28:19 -0800
Subject: [PATCH] mutex: comments and name clarity

---
 main.cpp | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/main.cpp b/main.cpp
index 4ff5749..2912aad 100644
--- a/main.cpp
+++ b/main.cpp
@@ -18,10 +18,10 @@ typedef void *(*ThreadTask)(const struct thread_data &);
 typedef void *(*PthreadFun)(void *arg);
 
 struct thread_group {
-  bool wants_mutex[NUM_THREADS] = {0};
-  bool has_mutex[NUM_THREADS] = {0};
-  bool manager_took_mutex[NUM_THREADS] = {0};
-  bool threads_finished[NUM_THREADS] = {0};
+  bool wants_mutex[NUM_THREADS] = {0};       // set by the thread
+  bool has_mutex[NUM_THREADS] = {0};         // set by us, read by thread
+  bool can_ask_for_mutex[NUM_THREADS] = {1}; // set by us, read by thread
+  bool threads_finished[NUM_THREADS] = {0};  // set by thread
   ThreadTask task;
   size_t total_threads;
   void *data;
@@ -31,7 +31,7 @@ struct thread_data {
   size_t id;
   bool *wants_mutex;
   const bool *has_mutex;
-  const bool *manager_took_mutex;
+  const bool *can_ask_for_mutex;
   bool *is_finished;
   void *data;
 };
@@ -56,7 +56,7 @@ void *thread_task_increment(const struct thread_data &thread) {
     {
 
       // wait for permission to ask for the mutex
-      while (!*thread.manager_took_mutex)
+      while (!*thread.can_ask_for_mutex)
         ;
       // say we want the mutex
       (*thread.wants_mutex) = true;
@@ -105,8 +105,8 @@ void do_threading(struct thread_group threads) {
          threads.total_threads * sizeof(*threads.threads_finished));
 
   // at the start, we have the mutex and haven't given it
-  memset(threads.manager_took_mutex, 1,
-         threads.total_threads * sizeof(*threads.manager_took_mutex));
+  memset(threads.can_ask_for_mutex, 1,
+         threads.total_threads * sizeof(*threads.can_ask_for_mutex));
 
   // create thread data
   for (size_t tid = 0; tid < threads.total_threads; ++tid) {
@@ -114,7 +114,7 @@ void do_threading(struct thread_group threads) {
         .id = tid,
         .wants_mutex = &threads.wants_mutex[tid],
         .has_mutex = &threads.has_mutex[tid],
-        .manager_took_mutex = &threads.manager_took_mutex[tid],
+        .can_ask_for_mutex = &threads.can_ask_for_mutex[tid],
         .is_finished = &threads.threads_finished[tid],
         .data = threads.data,
     };
@@ -154,9 +154,9 @@ void do_threading(struct thread_group threads) {
 
               // take the mutex from the thread that has it
               threads.has_mutex[tid_has] = false;
-              threads.manager_took_mutex[tid_has] = true;
+              threads.can_ask_for_mutex[tid_has] = true;
               // give the mutex to the thread that wants it
-              threads.manager_took_mutex[tid_wants] = false;
+              threads.can_ask_for_mutex[tid_wants] = false;
               threads.has_mutex[tid_wants] = true;
             }