gc: some renames

GC module is responsible not only for garbage collection, but also for
tracking consumers and making checkpoints. Soon it will also incorporate
the checkpoint daemon. Let's prefix all members related to the cleanup
procedure accordingly to avoid confusion.

src/box/gc.c

@@ -59,7 +59,7 @@
 struct gc_state gc;
 
 static int
-gc_fiber_f(va_list);
+gc_cleanup_fiber_f(va_list);
 
 /**
  * Comparator used for ordering gc_consumer objects by signature
@@ -107,13 +107,13 @@ gc_init(void)
 	vclock_create(&gc.vclock);
 	rlist_create(&gc.checkpoints);
 	gc_tree_new(&gc.consumers);
-	fiber_cond_create(&gc.cond);
+	fiber_cond_create(&gc.cleanup_cond);
 
-	gc.fiber = fiber_new("gc", gc_fiber_f);
-	if (gc.fiber == NULL)
+	gc.cleanup_fiber = fiber_new("gc", gc_cleanup_fiber_f);
+	if (gc.cleanup_fiber == NULL)
 		panic("failed to start garbage collection fiber");
 
-	fiber_start(gc.fiber);
+	fiber_start(gc.cleanup_fiber);
 }
 
 void
@@ -147,7 +147,7 @@ gc_free(void)
  * this function is specified by box.cfg.checkpoint_count.
  */
 static void
-gc_run(void)
+gc_run_cleanup(void)
 {
 	bool run_wal_gc = false;
 	bool run_engine_gc = false;
@@ -209,20 +209,20 @@ gc_run(void)
 }
 
 static int
-gc_fiber_f(va_list ap)
+gc_cleanup_fiber_f(va_list ap)
 {
 	(void)ap;
 	while (!fiber_is_cancelled()) {
-		int delta = gc.scheduled - gc.completed;
+		int delta = gc.cleanup_scheduled - gc.cleanup_completed;
 		if (delta == 0) {
 			/* No pending garbage collection. */
 			fiber_sleep(TIMEOUT_INFINITY);
 			continue;
 		}
 		assert(delta > 0);
-		gc_run();
-		gc.completed += delta;
-		fiber_cond_signal(&gc.cond);
+		gc_run_cleanup();
+		gc.cleanup_completed += delta;
+		fiber_cond_signal(&gc.cleanup_cond);
 	}
 	return 0;
 }
@@ -231,7 +231,7 @@ gc_fiber_f(va_list ap)
  * Trigger asynchronous garbage collection.
  */
 static void
-gc_schedule(void)
+gc_schedule_cleanup(void)
 {
 	/*
 	 * Do not wake up the background fiber if it's executing
@@ -241,8 +241,8 @@ gc_schedule(void)
 	 * then - it will rerun garbage collection as soon as
 	 * the current round completes.
 	 */
-	if (gc.scheduled++ == gc.completed)
-		fiber_wakeup(gc.fiber);
+	if (gc.cleanup_scheduled++ == gc.cleanup_completed)
+		fiber_wakeup(gc.cleanup_fiber);
 }
 
 /**
@@ -250,11 +250,11 @@ gc_schedule(void)
  * to this point to complete.
  */
 static void
-gc_wait(void)
+gc_wait_cleanup(void)
 {
-	unsigned scheduled = gc.scheduled;
-	while (gc.completed < scheduled)
-		fiber_cond_wait(&gc.cond);
+	unsigned scheduled = gc.cleanup_scheduled;
+	while (gc.cleanup_completed < scheduled)
+		fiber_cond_wait(&gc.cleanup_cond);
 }
 
 void
@@ -284,7 +284,7 @@ gc_advance(const struct vclock *vclock)
 
 		consumer = next;
 	}
-	gc_schedule();
+	gc_schedule_cleanup();
 }
 
 void
@@ -305,7 +305,7 @@ gc_add_checkpoint(const struct vclock *vclock)
 		 * Rerun the garbage collector in this case, just
 		 * in case box.cfg.checkpoint_count has changed.
 		 */
-		gc_schedule();
+		gc_schedule_cleanup();
 		return;
 	}
 	assert(last_checkpoint == NULL ||
@@ -324,7 +324,7 @@ gc_add_checkpoint(const struct vclock *vclock)
 	rlist_add_tail_entry(&gc.checkpoints, checkpoint, in_checkpoints);
 	gc.checkpoint_count++;
 
-	gc_schedule();
+	gc_schedule_cleanup();
 }
 
 int
@@ -381,7 +381,7 @@ gc_checkpoint(void)
 	 * files have been removed.
 	 */
 	if (rc == 0)
-		gc_wait();
+		gc_wait_cleanup();
 
 	return rc;
 }
@@ -402,7 +402,7 @@ void
 gc_unref_checkpoint(struct gc_checkpoint_ref *ref)
 {
 	rlist_del_entry(ref, in_refs);
-	gc_schedule();
+	gc_schedule_cleanup();
 }
 
 struct gc_consumer *
@@ -430,7 +430,7 @@ gc_consumer_unregister(struct gc_consumer *consumer)
 {
 	if (!consumer->is_inactive) {
 		gc_tree_remove(&gc.consumers, consumer);
-		gc_schedule();
+		gc_schedule_cleanup();
 	}
 	gc_consumer_delete(consumer);
 }
@@ -464,7 +464,7 @@ gc_consumer_advance(struct gc_consumer *consumer, const struct vclock *vclock)
 	if (update_tree)
 		gc_tree_insert(&gc.consumers, consumer);
 
-	gc_schedule();
+	gc_schedule_cleanup();
 }
 
 struct gc_consumer *

src/box/gc.h

@@ -123,13 +123,13 @@ struct gc_state {
 	/** Registered consumers, linked by gc_consumer::node. */
 	gc_tree_t consumers;
 	/** Fiber that removes old files in the background. */
-	struct fiber *fiber;
+	struct fiber *cleanup_fiber;
 	/**
-	 * Condition variable signaled by the background fiber
+	 * Condition variable signaled by the cleanup fiber
 	 * whenever it completes a round of garbage collection.
 	 * Used to wait for garbage collection to complete.
 	 */
-	struct fiber_cond cond;
+	struct fiber_cond cleanup_cond;
 	/**
 	 * The following two members are used for scheduling
 	 * background garbage collection and waiting for it to
@@ -141,7 +141,7 @@ struct gc_state {
 	 * sleep until @completed reaches the value of @scheduled
 	 * taken at that moment of time.
 	 */
-	unsigned completed, scheduled;
+	unsigned cleanup_completed, cleanup_scheduled;
 	/**
 	 * Set if there's a fiber making a checkpoint right now.
 	 */