pthreadpool: add pthreadpool_max_threads() and pthreadpool_queued_jobs() helpers

These can be used to implement some kind of flow control in the caller.
E.g. unless pthreadpool_queued_jobs() is lower than
pthreadpool_max_threads() is good to prepare new jobs.

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>

lib/pthreadpool/pthreadpool.c

@@ -196,6 +196,29 @@ int pthreadpool_init(unsigned max_threads, struct pthreadpool **presult,
 	return 0;
 }
 
+size_t pthreadpool_max_threads(struct pthreadpool *pool)
+{
+	return pool->max_threads;
+}
+
+size_t pthreadpool_queued_jobs(struct pthreadpool *pool)
+{
+	int res;
+	int unlock_res;
+	size_t ret;
+
+	res = pthread_mutex_lock(&pool->mutex);
+	if (res != 0) {
+		return 0;
+	}
+
+	ret = pool->num_jobs;
+
+	unlock_res = pthread_mutex_unlock(&pool->mutex);
+	assert(unlock_res == 0);
+	return ret;
+}
+
 static void pthreadpool_prepare_pool(struct pthreadpool *pool)
 {
 	int ret;

lib/pthreadpool/pthreadpool.h

@@ -50,6 +50,27 @@ int pthreadpool_init(unsigned max_threads, struct pthreadpool **presult,
 				      void *private_data),
 		     void *signal_fn_private_data);
 
+/**
+ * @brief Get the max threads value of pthreadpool
+ *
+ * @note This can be 0 for strict sync processing.
+ *
+ * @param[in]	pool		The pool
+ * @return			number of possible threads
+ */
+size_t pthreadpool_max_threads(struct pthreadpool *pool);
+
+/**
+ * @brief The number of queued jobs of pthreadpool
+ *
+ * This is the number of jobs added by pthreadpool_add_job(),
+ * which are not yet processed by a thread.
+ *
+ * @param[in]	pool		The pool
+ * @return			The number of jobs
+ */
+size_t pthreadpool_queued_jobs(struct pthreadpool *pool);
+
 /**
  * @brief Destroy a pthreadpool
  *

lib/pthreadpool/pthreadpool_sync.c

@@ -52,6 +52,16 @@ int pthreadpool_init(unsigned max_threads, struct pthreadpool **presult,
 	return 0;
 }
 
+size_t pthreadpool_max_threads(struct pthreadpool *pool)
+{
+	return 0;
+}
+
+size_t pthreadpool_queued_jobs(struct pthreadpool *pool)
+{
+	return 0;
+}
+
 int pthreadpool_add_job(struct pthreadpool *pool, int job_id,
 			void (*fn)(void *private_data), void *private_data)
 {