Removing old redundant code from bio.c (#11136)

* Remove redundant array bio_pending[]. Value at index i identically reflects the
length of list bio_jobs[i]. Better use listLength() instead and discard this array.
(no critical section issues to concern about).

changed returned value of bioPendingJobsOfType() from "long long" to "long".

Remove unused API. Maybe we will use this API later.

src/bio.c

@@ -64,15 +64,7 @@
 static pthread_t bio_threads[BIO_NUM_OPS];
 static pthread_mutex_t bio_mutex[BIO_NUM_OPS];
 static pthread_cond_t bio_newjob_cond[BIO_NUM_OPS];
-static pthread_cond_t bio_step_cond[BIO_NUM_OPS];
 static list *bio_jobs[BIO_NUM_OPS];
-/* The following array is used to hold the number of pending jobs for every
- * OP type. This allows us to export the bioPendingJobsOfType() API that is
- * useful when the main thread wants to perform some operation that may involve
- * objects shared with the background thread. The main thread will just wait
- * that there are no longer jobs of this type to be executed before performing
- * the sensible operation. This data is also useful for reporting. */
-static unsigned long long bio_pending[BIO_NUM_OPS];
 
 /* This structure represents a background Job. It is only used locally to this
  * file as the API does not expose the internals at all. */
@@ -107,9 +99,7 @@ void bioInit(void) {
     for (j = 0; j < BIO_NUM_OPS; j++) {
         pthread_mutex_init(&bio_mutex[j],NULL);
         pthread_cond_init(&bio_newjob_cond[j],NULL);
-        pthread_cond_init(&bio_step_cond[j],NULL);
         bio_jobs[j] = listCreate();
-        bio_pending[j] = 0;
     }
 
     /* Set the stack size as by default it may be small in some system */
@@ -135,7 +125,6 @@ void bioInit(void) {
 void bioSubmitJob(int type, bio_job *job) {
     pthread_mutex_lock(&bio_mutex[type]);
     listAddNodeTail(bio_jobs[type],job);
-    bio_pending[type]++;
     pthread_cond_signal(&bio_newjob_cond[type]);
     pthread_mutex_unlock(&bio_mutex[type]);
 }
@@ -257,40 +246,14 @@ void *bioProcessBackgroundJobs(void *arg) {
          * jobs to process we'll block again in pthread_cond_wait(). */
         pthread_mutex_lock(&bio_mutex[type]);
         listDelNode(bio_jobs[type],ln);
-        bio_pending[type]--;
-
-        /* Unblock threads blocked on bioWaitStepOfType() if any. */
-        pthread_cond_broadcast(&bio_step_cond[type]);
     }
 }
 
 /* Return the number of pending jobs of the specified type. */
-unsigned long long bioPendingJobsOfType(int type) {
+unsigned long bioPendingJobsOfType(int type) {
     unsigned long long val;
     pthread_mutex_lock(&bio_mutex[type]);
-    val = bio_pending[type];
+    val = listLength(bio_jobs[type]);
-    pthread_mutex_unlock(&bio_mutex[type]);
-    return val;
-}
-
-/* If there are pending jobs for the specified type, the function blocks
- * and waits that the next job was processed. Otherwise the function
- * does not block and returns ASAP.
- *
- * The function returns the number of jobs still to process of the
- * requested type.
- *
- * This function is useful when from another thread, we want to wait
- * a bio.c thread to do more work in a blocking way.
- */
-unsigned long long bioWaitStepOfType(int type) {
-    unsigned long long val;
-    pthread_mutex_lock(&bio_mutex[type]);
-    val = bio_pending[type];
-    if (val != 0) {
-        pthread_cond_wait(&bio_step_cond[type],&bio_mutex[type]);
-        val = bio_pending[type];
-    }
     pthread_mutex_unlock(&bio_mutex[type]);
     return val;
 }

src/bio.h

@@ -34,8 +34,7 @@ typedef void lazy_free_fn(void *args[]);
 
 /* Exported API */
 void bioInit(void);
-unsigned long long bioPendingJobsOfType(int type);
+unsigned long bioPendingJobsOfType(int type);
-unsigned long long bioWaitStepOfType(int type);
 void bioKillThreads(void);
 void bioCreateCloseJob(int fd, int need_fsync);
 void bioCreateFsyncJob(int fd);

src/server.c

@@ -5600,7 +5600,7 @@ sds genRedisInfoString(dict *section_dict, int all_sections, int everything) {
                 "aof_base_size:%lld\r\n"
                 "aof_pending_rewrite:%d\r\n"
                 "aof_buffer_length:%zu\r\n"
-                "aof_pending_bio_fsync:%llu\r\n"
+                "aof_pending_bio_fsync:%lu\r\n"
                 "aof_delayed_fsync:%lu\r\n",
                 (long long) server.aof_current_size,
                 (long long) server.aof_rewrite_base_size,