MDEV-17441 - InnoDB transition to C++11 atomics

buf_page_t::buf_fix_count transition to Atomic_counter.

Author: svoj

include/my_counter.h

@@ -28,6 +28,8 @@ template <typename Type> class Atomic_counter
   Type sub(Type i) { return m_counter.fetch_sub(i, std::memory_order_relaxed); }
 
 public:
+  Atomic_counter(const Atomic_counter<Type> &rhs)
+  { m_counter.store(rhs, std::memory_order_relaxed); }
   Atomic_counter(Type val): m_counter(val) {}
   Atomic_counter() {}
 

storage/innobase/buf/buf0buf.cc

@@ -3404,7 +3404,7 @@ buf_pool_watch_set(
 		}
 
 		/* Add to an existing watch. */
-		buf_block_fix(bpage);
+		bpage->fix();
 		return(NULL);
 	}
 
@@ -3544,7 +3544,7 @@ void buf_pool_watch_unset(const page_id_t page_id)
 	increments buf_fix_count. */
 	bpage = buf_page_hash_get_low(buf_pool, page_id);
 
-	if (buf_block_unfix(bpage) == 0
+	if (bpage->unfix() == 0
 	    && buf_pool_watch_is_sentinel(buf_pool, bpage)) {
 		buf_pool_watch_remove(buf_pool, bpage);
 	}
@@ -3777,7 +3777,7 @@ buf_page_get_zip(
 
 	case BUF_BLOCK_ZIP_PAGE:
 	case BUF_BLOCK_ZIP_DIRTY:
-		buf_block_fix(bpage);
+		bpage->fix();
 		block_mutex = &buf_pool->zip_mutex;
 		mutex_enter(block_mutex);
 		goto got_block;
@@ -4296,10 +4296,10 @@ buf_page_get_gen(
 						= buf_page_get_mutex(
 							&fix_block->page);
 					mutex_enter(fix_mutex);
-					buf_block_fix(fix_block);
+					fix_block->fix();
 					mutex_exit(fix_mutex);
 				} else {
-					buf_block_fix(fix_block);
+					fix_block->fix();
 				}
 
 				/* Now safe to release page_hash mutex */
@@ -4406,10 +4406,10 @@ buf_page_get_gen(
 		BPageMutex*	fix_mutex = buf_page_get_mutex(
 			&fix_block->page);
 		mutex_enter(fix_mutex);
-		buf_block_fix(fix_block);
+		fix_block->fix();
 		mutex_exit(fix_mutex);
 	} else {
-		buf_block_fix(fix_block);
+		fix_block->fix();
 	}
 
 	/* Now safe to release page_hash mutex */
@@ -4432,7 +4432,7 @@ buf_page_get_gen(
 			/* The page is being read to buffer pool,
 			but we cannot wait around for the read to
 			complete. */
-			buf_block_unfix(fix_block);
+			fix_block->unfix();
 
 			return(NULL);
 		}
@@ -4448,7 +4448,7 @@ buf_page_get_gen(
 			/* This suggests that the page is being flushed.
 			Avoid returning reference to this page.
 			Instead wait for the flush action to complete. */
-			buf_block_unfix(fix_block);
+			fix_block->unfix();
 			os_thread_sleep(WAIT_FOR_WRITE);
 			goto loop;
 		}
@@ -4457,7 +4457,7 @@ buf_page_get_gen(
 evict_from_pool:
 			ut_ad(!fix_block->page.oldest_modification);
 			buf_pool_mutex_enter(buf_pool);
-			buf_block_unfix(fix_block);
+			fix_block->unfix();
 
 			if (!buf_LRU_free_page(&fix_block->page, true)) {
 				ut_ad(0);
@@ -4475,7 +4475,7 @@ buf_page_get_gen(
 			adaptive hash index.  There cannot be an
 			adaptive hash index for a compressed-only
 			page, so do not bother decompressing the page. */
-			buf_block_unfix(fix_block);
+			fix_block->unfix();
 
 			return(NULL);
 		}
@@ -4489,7 +4489,7 @@ buf_page_get_gen(
 			/* This condition often occurs when the buffer
 			is not buffer-fixed, but I/O-fixed by
 			buf_page_init_for_read(). */
-			buf_block_unfix(fix_block);
+			fix_block->unfix();
 
 			/* The block is buffer-fixed or I/O-fixed.
 			Try again later. */
@@ -4518,7 +4518,7 @@ buf_page_get_gen(
 		/* Buffer-fixing prevents the page_hash from changing. */
 		ut_ad(bpage == buf_page_hash_get_low(buf_pool, page_id));
 
-		buf_block_unfix(fix_block);
+		fix_block->unfix();
 
 		buf_page_mutex_enter(block);
 		mutex_enter(&buf_pool->zip_mutex);
@@ -4610,7 +4610,7 @@ buf_page_get_gen(
 				buf_page_mutex_exit(fix_block);
 
 				--buf_pool->n_pend_unzip;
-				buf_block_unfix(fix_block);
+				fix_block->unfix();
 				buf_pool_mutex_exit(buf_pool);
 				rw_lock_x_unlock(&fix_block->lock);
 
@@ -4673,7 +4673,7 @@ buf_page_get_gen(
 
 		buf_pool_mutex_enter(buf_pool);
 
-		buf_block_unfix(fix_block);
+		fix_block->unfix();
 
 		/* Now we are only holding the buf_pool->mutex,
 		not block->mutex or hash_lock. Blocks cannot be
@@ -4732,7 +4732,7 @@ buf_page_get_gen(
 
 		buf_page_mutex_exit(fix_block);
 
-		buf_block_fix(fix_block);
+		fix_block->fix();
 
 		/* Failed to evict the page; change it directly */
 
@@ -5233,7 +5233,7 @@ buf_page_init(
 
 		ut_a(buf_fix_count > 0);
 
-		my_atomic_add32((int32*) &block->page.buf_fix_count, buf_fix_count);
+		block->page.buf_fix_count += buf_fix_count;
 
 		buf_pool_watch_remove(buf_pool, hash_page);
 	} else {
@@ -5474,7 +5474,7 @@ buf_page_init_for_read(
 
 			ut_a(buf_fix_count > 0);
 
-			my_atomic_add32((int32*) &bpage->buf_fix_count, buf_fix_count);
+			bpage->buf_fix_count += buf_fix_count;
 
 			ut_ad(buf_pool_watch_is_sentinel(buf_pool, watch_page));
 			buf_pool_watch_remove(buf_pool, watch_page);

storage/innobase/buf/buf0lru.cc

@@ -2459,7 +2459,7 @@ buf_LRU_print_instance(
 
 		if (bpage->buf_fix_count) {
 			fprintf(stderr, "buffix count %u ",
-				bpage->buf_fix_count);
+				uint32_t(bpage->buf_fix_count));
 		}
 
 		if (buf_page_get_io_fix(bpage)) {

storage/innobase/include/buf0buf.h

@@ -665,37 +665,6 @@ buf_block_buf_fix_inc_func(
 	buf_block_t*	block)	/*!< in/out: block to bufferfix */
 	MY_ATTRIBUTE((nonnull));
 
-/** Increments the bufferfix count.
-@param[in,out]	bpage	block to bufferfix
-@return the count */
-UNIV_INLINE
-ulint
-buf_block_fix(
-	buf_page_t*	bpage);
-
-/** Increments the bufferfix count.
-@param[in,out]	block	block to bufferfix
-@return the count */
-UNIV_INLINE
-ulint
-buf_block_fix(
-	buf_block_t*	block);
-
-/** Decrements the bufferfix count.
-@param[in,out]	bpage	block to bufferunfix
-@return	the remaining buffer-fix count */
-UNIV_INLINE
-ulint
-buf_block_unfix(
-	buf_page_t*	bpage);
-/** Decrements the bufferfix count.
-@param[in,out]	block	block to bufferunfix
-@return	the remaining buffer-fix count */
-UNIV_INLINE
-ulint
-buf_block_unfix(
-	buf_block_t*	block);
-
 # ifdef UNIV_DEBUG
 /** Increments the bufferfix count.
 @param[in,out]	b	block to bufferfix
@@ -1490,7 +1459,7 @@ class buf_page_t {
 	page_size_t	size;
 
 	/** Count of how manyfold this block is currently bufferfixed. */
-	ib_uint32_t	buf_fix_count;
+	Atomic_counter<uint32_t>	buf_fix_count;
 
 	/** type of pending I/O operation; also protected by
 	buf_pool->mutex for writes only */
@@ -1645,6 +1614,14 @@ class buf_page_t {
 					protected by buf_pool->zip_mutex
 					or buf_block_t::mutex. */
 # endif /* UNIV_DEBUG */
+
+  void fix() { buf_fix_count++; }
+  uint32_t unfix()
+  {
+    uint32_t count= buf_fix_count--;
+    ut_ad(count != 0);
+    return count - 1;
+  }
 };
 
 /** The buffer control block structure */
@@ -1808,6 +1785,9 @@ struct buf_block_t{
 					and accessed; we introduce this new
 					mutex in InnoDB-5.1 to relieve
 					contention on the buffer pool mutex */
+
+  void fix() { page.fix(); }
+  uint32_t unfix() { return page.unfix(); }
 };
 
 /** Check if a buf_block_t object is in a valid state

storage/innobase/include/buf0buf.ic

@@ -945,28 +945,6 @@ buf_block_get_modify_clock(
 	return(block->modify_clock);
 }
 
-/** Increments the bufferfix count.
-@param[in,out]	bpage	block to bufferfix
-@return the count */
-UNIV_INLINE
-ulint
-buf_block_fix(
-	buf_page_t*	bpage)
-{
-	return uint32(my_atomic_add32((int32*) &bpage->buf_fix_count, 1) + 1);
-}
-
-/** Increments the bufferfix count.
-@param[in,out]	block	block to bufferfix
-@return the count */
-UNIV_INLINE
-ulint
-buf_block_fix(
-	buf_block_t*	block)
-{
-	return(buf_block_fix(&block->page));
-}
-
 /*******************************************************************//**
 Increments the bufferfix count. */
 UNIV_INLINE
@@ -990,32 +968,7 @@ buf_block_buf_fix_inc_func(
 	}
 #endif /* UNIV_DEBUG */
 
-	buf_block_fix(block);
-}
-
-/** Decrements the bufferfix count.
-@param[in,out]	bpage	block to bufferunfix
-@return	the remaining buffer-fix count */
-UNIV_INLINE
-ulint
-buf_block_unfix(
-	buf_page_t*	bpage)
-{
-	uint32	count = uint32(my_atomic_add32((int32*) &bpage->buf_fix_count,
-					       -1));
-	ut_ad(count != 0);
-	return count - 1;
-}
-
-/** Decrements the bufferfix count.
-@param[in,out]	block	block to bufferunfix
-@return the remaining buffer-fix count */
-UNIV_INLINE
-ulint
-buf_block_unfix(
-	buf_block_t*	block)
-{
-	return(buf_block_unfix(&block->page));
+	block->fix();
 }
 
 /*******************************************************************//**
@@ -1026,7 +979,7 @@ buf_block_buf_fix_dec(
 /*==================*/
 	buf_block_t*	block)	/*!< in/out: block to bufferunfix */
 {
-	buf_block_unfix(block);
+	block->unfix();
 
 #ifdef UNIV_DEBUG
 	/* No debug latch is acquired if block belongs to system temporary.
@@ -1283,7 +1236,7 @@ buf_page_release_zip(
 		/* Fall through */
 	case BUF_BLOCK_ZIP_PAGE:
 	case BUF_BLOCK_ZIP_DIRTY:
-		buf_block_unfix(reinterpret_cast<buf_block_t*>(bpage));
+		reinterpret_cast<buf_block_t*>(bpage)->unfix();
 		return;
 
 	case BUF_BLOCK_POOL_WATCH:

storage/innobase/include/mtr0mtr.ic

@@ -170,7 +170,7 @@ mtr_t::release_block_at_savepoint(
 
 	ut_a(slot->object == block);
 
-	buf_block_unfix(reinterpret_cast<buf_block_t*>(block));
+	reinterpret_cast<buf_block_t*>(block)->unfix();
 
 	buf_page_release_latch(block, slot->type);
 

storage/innobase/mtr/mtr0mtr.cc

@@ -191,7 +191,7 @@ memo_slot_release(mtr_memo_slot_t* slot)
 
 		block = reinterpret_cast<buf_block_t*>(slot->object);
 
-		buf_block_unfix(block);
+		block->unfix();
 		buf_page_release_latch(block, slot->type);
 		break;
 	}
@@ -228,7 +228,7 @@ memo_block_unfix(mtr_memo_slot_t* slot)
 	case MTR_MEMO_PAGE_S_FIX:
 	case MTR_MEMO_PAGE_X_FIX:
 	case MTR_MEMO_PAGE_SX_FIX: {
-		buf_block_unfix(reinterpret_cast<buf_block_t*>(slot->object));
+		reinterpret_cast<buf_block_t*>(slot->object)->unfix();
 		break;
 	}