Ensure worker threads actually exit when it is time

This includes a small refactoring to use a new enum (workqueue_reply_t)
for the return values instead of just ints.

2 files changed, 21 insertions, 19 deletions

diff --git a/src/common/workqueue.c b/src/common/workqueue.c
index b0b004dc25..c467bdf43b 100644
--- a/src/common/workqueue.c
+++ b/src/common/workqueue.c
@@ -25,7 +25,7 @@ struct threadpool_s {
   unsigned generation;
 
   /** Function that should be run for updates on each thread. */
-  int (*update_fn)(void *, void *);
+  workqueue_reply_t (*update_fn)(void *, void *);
   /** Function to free update arguments if they can't be run. */
   void (*free_update_arg_fn)(void *);
   /** Array of n_threads update arguments. */
@@ -56,7 +56,7 @@ struct workqueue_entry_s {
   /** True iff this entry is waiting for a worker to start processing it. */
   uint8_t pending;
   /** Function to run in the worker thread. */
-  int (*fn)(void *state, void *arg);
+  workqueue_reply_t (*fn)(void *state, void *arg);
   /** Function to run while processing the reply queue. */
   void (*reply_fn)(void *arg);
   /** Argument for the above functions. */
@@ -96,7 +96,7 @@ static void queue_reply(replyqueue_t *queue, workqueue_entry_t *work);
  * <b>fn</b> in the worker thread, and <b>reply_fn</b> in the main
  * thread. See threadpool_queue_work() for full documentation. */
 static workqueue_entry_t *
-workqueue_entry_new(int (*fn)(void*, void*),
+workqueue_entry_new(workqueue_reply_t (*fn)(void*, void*),
                     void (*reply_fn)(void*),
                     void *arg)
 {
@@ -172,7 +172,7 @@ worker_thread_main(void *thread_)
   workerthread_t *thread = thread_;
   threadpool_t *pool = thread->in_pool;
   workqueue_entry_t *work;
-  int result;
+  workqueue_reply_t result;
 
   tor_mutex_acquire(&pool->lock);
   while (1) {
@@ -182,13 +182,14 @@ worker_thread_main(void *thread_)
       if (thread->in_pool->generation != thread->generation) {
         void *arg = thread->in_pool->update_args[thread->index];
         thread->in_pool->update_args[thread->index] = NULL;
-        int (*update_fn)(void*,void*) = thread->in_pool->update_fn;
+        workqueue_reply_t (*update_fn)(void*,void*) =
+            thread->in_pool->update_fn;
         thread->generation = thread->in_pool->generation;
         tor_mutex_release(&pool->lock);
 
-        int r = update_fn(thread->state, arg);
+        workqueue_reply_t r = update_fn(thread->state, arg);
 
-        if (r < 0) {
+        if (r != WQ_RPL_REPLY) {
           return;
         }
 
@@ -208,7 +209,7 @@ worker_thread_main(void *thread_)
       queue_reply(thread->reply_queue, work);
 
       /* We may need to exit the thread. */
-      if (result >= WQ_RPL_ERROR) {
+      if (result != WQ_RPL_REPLY) {
         return;
       }
       tor_mutex_acquire(&pool->lock);
@@ -281,7 +282,7 @@ workerthread_new(void *state, threadpool_t *pool, replyqueue_t *replyqueue)
  */
 workqueue_entry_t *
 threadpool_queue_work(threadpool_t *pool,
-                      int (*fn)(void *, void *),
+                      workqueue_reply_t (*fn)(void *, void *),
                       void (*reply_fn)(void *),
                       void *arg)
 {
@@ -318,7 +319,7 @@ threadpool_queue_work(threadpool_t *pool,
 int
 threadpool_queue_update(threadpool_t *pool,
                          void *(*dup_fn)(void *),
-                         int (*fn)(void *, void *),
+                         workqueue_reply_t (*fn)(void *, void *),
                          void (*free_fn)(void *),
                          void *arg)
 {
diff --git a/src/common/workqueue.h b/src/common/workqueue.h
index 92e82b8a48..9ce1eadafc 100644
--- a/src/common/workqueue.h
+++ b/src/common/workqueue.h
@@ -15,21 +15,22 @@ typedef struct threadpool_s threadpool_t;
  * pool. */
 typedef struct workqueue_entry_s workqueue_entry_t;
 
-/** Possible return value from a work function: indicates success. */
-#define WQ_RPL_REPLY    0
-/** Possible return value from a work function: indicates fatal error */
-#define WQ_RPL_ERROR    1
-/** Possible return value from a work function: indicates thread is shutting
- * down. */
-#define WQ_RPL_SHUTDOWN 2
+/** Possible return value from a work function: */
+typedef enum {
+  WQ_RPL_REPLY = 0, /** indicates success */
+  WQ_RPL_ERROR = 1, /** indicates fatal error */
+  WQ_RPL_SHUTDOWN = 2, /** indicates thread is shutting down */
+} workqueue_reply_t;
 
 workqueue_entry_t *threadpool_queue_work(threadpool_t *pool,
-                                         int (*fn)(void *, void *),
+                                         workqueue_reply_t (*fn)(void *,
+                                                                 void *),
                                          void (*reply_fn)(void *),
                                          void *arg);
+
 int threadpool_queue_update(threadpool_t *pool,
                             void *(*dup_fn)(void *),
-                            int (*fn)(void *, void *),
+                            workqueue_reply_t (*fn)(void *, void *),
                             void (*free_fn)(void *),
                             void *arg);
 void *workqueue_entry_cancel(workqueue_entry_t *pending_work);