index-pack: drop type_cas mutex

The type_cas lock lost all of its callers in f08cbf60fe (index-pack: make quantum of work smaller, 2020-09-08), so we can safely delete it. The compiler didn't alert us that the variable became unused, because we still call pthread_mutex_init() and pthread_mutex_destroy() on it. It's worth considering also whether that commit was in error to remove the use of the lock. Why don't we need it now, if we did before, as described in ab791dd138 (index-pack: fix race condition with duplicate bases, 2014-08-29)? I think the answer is that we now look at and assign the child_obj->real_type field in the main thread while holding the work_lock(). So we don't have to worry about racing with the worker threads. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Jeff King committed Oct 7, 2020 at 14:19 UTC bebe1719470078b000950b0cca520d3e533996a9

1 file changed -6

builtin/index-pack.c

-6

@@ -159,10 +159,6 @@ static pthread_mutex_t deepest_delta_mutex;

159 #define deepest_delta_lock() lock_mutex(&deepest_delta_mutex)

160 #define deepest_delta_unlock() unlock_mutex(&deepest_delta_mutex)

161

162 -static pthread_mutex_t type_cas_mutex;

163 -#define type_cas_lock() lock_mutex(&type_cas_mutex)

164 -#define type_cas_unlock() unlock_mutex(&type_cas_mutex)

165 -

162 static pthread_key_t key;

163

164 static inline void lock_mutex(pthread_mutex_t *mutex)

@@ -186,7 +182,6 @@ static void init_thread(void)

182 init_recursive_mutex(&read_mutex);

183 pthread_mutex_init(&counter_mutex, NULL);

184 pthread_mutex_init(&work_mutex, NULL);

189 - pthread_mutex_init(&type_cas_mutex, NULL);

185 if (show_stat)

186 pthread_mutex_init(&deepest_delta_mutex, NULL);

187 pthread_key_create(&key, NULL);

@@ -209,7 +204,6 @@ static void cleanup_thread(void)

204 pthread_mutex_destroy(&read_mutex);

205 pthread_mutex_destroy(&counter_mutex);

206 pthread_mutex_destroy(&work_mutex);

212 - pthread_mutex_destroy(&type_cas_mutex);

207 if (show_stat)

208 pthread_mutex_destroy(&deepest_delta_mutex);

209 for (i = 0; i < nr_threads; i++)