Re: [tarantool-patches] Re: [PATCH v2 1/1] box: create bigrefs for tuples

[Vladislav Shpilevoy <v.shpilevoy@tarantool.org>]

Thanks for the patch, Mergen! Please look at my 5 comments.

Vova, please, take a look on the patch. I have pasted it at the end
of the letter.

On 04/06/2018 17:21, Imeev Mergen wrote:
> 
> 
> On 06/04/2018 02:21 PM, Vladislav Shpilevoy wrote:
>> Hello. Thanks for the patch! It is almost perfect! See 6 comments
>> below.
>>
>> On 01/06/2018 18:41, imeevma@tarantool.org wrote:
>>> Due to limitation of reference counters for tuple being only
>>> 65535 it was possible to reach this limitation. This patch
>>> increases capacity of reference counters to 4 billions.
>>>
>>> Closes #3224
>>> ---
>>> Branch: https://github.com/tarantool/tarantool/tree/imeevma/gh-3224-tuple-bigrefs
>>> Issue: https://github.com/tarantool/tarantool/issues/3224
>>>
> 
> commit 7b7965f6c5462142a607d9db542d698fc94fbbbe
> Author: Mergen Imeev <imeevma@gmail.com>
> Date:   Mon May 28 19:17:51 2018 +0300
> 
>      box: create bigrefs for tuples
> 
>      Due to limitation of reference counters for tuple being only
>      65535 it was possible to reach this limitation. This patch
>      increases capacity of reference counters to 4 billions.
> 
>      Closes #3224
> 
> diff --git a/src/box/tuple.c b/src/box/tuple.c
> index 014f374..6e63433 100644
> --- a/src/box/tuple.c
> +++ b/src/box/tuple.c
> @@ -48,6 +48,26 @@ enum {
>       OBJSIZE_MIN = 16,
>   };
> 
> +/**
> + * Container for big reference counters. Contains array of big
> + * reference counters, size of this array and number of non-zero
> + * big reference counters. When reference counter of tuple becomes
> + * more than 32767, field refs of this tuple becomes index of big
> + * reference counter in big reference counter array and field
> + * is_bigref is set true. The moment big reference becomes equal
> + * 32767 it is set to 0, refs of the tuple becomes 32767 and
> + * is_bigref becomes false. Big reference counter can be equal to
> + * 0 or be more than 32767.
> + */
> +struct bigref_list {
> +    /** Array of big reference counters */
> +    uint32_t *refs;
> +    /** Number of non-zero elements in the array */
> +    uint16_t size;
> +    /** Capacity of the array */
> +    uint16_t capacity;
> +};

1. Instead of

     struct name {
         ...
     };
     static struct name name;

you can do this

     static struct name {
         ...
     } name;

> +
>   static const double ALLOC_FACTOR = 1.05;
> 
>   /**
> @@ -151,6 +177,15 @@ tuple_validate_raw(struct tuple_format *format, const char *tuple)
>       return 0;
>   }
> 
> +/** Initialize big references container. */
> +static inline void
> +bigref_list_create()
> +{
> +    bigref_list.size = 0;
> +    bigref_list.refs = NULL;
> +    bigref_list.capacity = 0;

2. Memset is faster than per-member resetting. We with
Vladimir Davydov have benched it.

> +/**
> + * Return index for new big reference counter and allocate memory
> + * if needed.
> + * @retval index for new big reference counter.
> + */
> +static inline uint16_t
> +tuple_bigref_retrieve()
> +{
> +    if (bigref_list.size < bigref_list.capacity) {
> +        uint16_t vacant_index = 0;
> +        while (bigref_list.refs[vacant_index] != 0)
> +            ++vacant_index;
> +        return vacant_index;
> +    }
> +    /* Extend the array. */
> +    uint16_t capacity = bigref_list.capacity;
> +    if (capacity == 0) {
> +        capacity = TUPLE_BIGREF_MIN_CAPACITY;
> +    } else {
> +        capacity *= TUPLE_BIGREF_FACTOR;
> +        if (capacity >= TUPLE_BIGREF_MAX_CAPACITY)

3. By such check you have limited the capacity with 16384 bigrefs instead of
32k. Capacity here is always a power of 2. TUPLE_BIGREF_MAX_CAPACITY is
2^15. So here after 2^14 you get overflow. 2^14 = 16384. I have fixed it on
the branch.

> +            panic("Too many big references");
> +    }
> +    uint32_t *refs = (uint32_t *) realloc(bigref_list.refs, capacity *
> +                          sizeof(*bigref_list.refs));
> +    if (refs == NULL) {
> +        panic("failed to reallocate %zu bytes: Cannot allocate"\
> +              " memory.", capacity * sizeof(*bigref_list.refs));
> +    }
> +    bigref_list.refs = refs;
> +    memset(bigref_list.refs + bigref_list.capacity, 0, capacity -
> +           bigref_list.capacity);
> +    bigref_list.capacity = capacity;
> +    return bigref_list.size++;
> +}
> +
> +/**
> + * Try to decrease allocated memory if it is possible. Free memory
> + * when size == 0.
> + */
> +static inline void
> +bigref_list_compact()
> +{
> +    if (bigref_list.size == 0) {
> +        bigref_list_destroy();
> +        return;
> +    }
> +    if (bigref_list.capacity == TUPLE_BIGREF_MIN_CAPACITY ||
> +        bigref_list.size > bigref_list.capacity / TUPLE_BIGREF_FACTOR)
> +        return;
> +    uint16_t capacity = bigref_list.capacity;
> +    while (bigref_list.refs[capacity - 1] == 0)
> +        capacity--;
> +    if (capacity < TUPLE_BIGREF_MIN_CAPACITY)
> +        capacity = TUPLE_BIGREF_MIN_CAPACITY;
> +    if (capacity > bigref_list.capacity / TUPLE_BIGREF_FACTOR)
> +        return;
> +    /* Round up capacity to the next highest power of 2*/
> +    capacity--;
> +    capacity |= capacity >> 1;
> +    capacity |= capacity >> 2;
> +    capacity |= capacity >> 4;
> +    capacity |= capacity >> 8;
> +    capacity |= capacity >> 16;

4. This is because blind copy and paste is bad. The algorithm implementation
I provided to you was for 32 bit unsigned integers, but here you have 16 bits
only, so capacity >> 16 is always 0.

> +    capacity++;
> +    uint32_t *refs = (uint32_t *) realloc(bigref_list.refs, capacity *
> +                          sizeof(*bigref_list.refs));
> +    if (refs == NULL)
> +        panic("failed to reallocate %zu bytes: Cannot allocate"\
> +              " memory.", capacity * sizeof(*bigref_list.refs));
> +    bigref_list.refs = refs;
> +    bigref_list.capacity = capacity;
> +}
> +

5. I have removed tuple_bless == NULL checks from all the code.

Here the patch:

============================================================================

commit 9d82fa9f9ae24c7dc91cf9dd7a416ec533fb8147
Author: Mergen Imeev <imeevma@gmail.com>
Date:   Mon May 28 19:17:51 2018 +0300

     box: create bigrefs for tuples
     
     Due to limitation of reference counters for tuple being only
     65535 it was possible to reach this limitation. This patch
     increases capacity of reference counters to 4 billions.
     
     Closes #3224

diff --git a/src/box/box.cc b/src/box/box.cc
index c728a4c53..42578613d 100644
--- a/src/box/box.cc
+++ b/src/box/box.cc
@@ -174,20 +174,22 @@ process_rw(struct request *request, struct space *space, struct tuple **result)
  		txn_rollback_stmt();
  		return -1;
  	}
+	if (result == NULL)
+		return txn_commit_stmt(txn, request);
+	*result = tuple;
+	if (tuple == NULL)
+		return txn_commit_stmt(txn, request);
  	/*
  	 * Pin the tuple locally before the commit,
  	 * otherwise it may go away during yield in
  	 * when WAL is written in autocommit mode.
  	 */
-	TupleRefNil ref(tuple);
-	if (txn_commit_stmt(txn, request) != 0)
-		return -1;
-	if (result != NULL) {
-		if (tuple != NULL && tuple_bless(tuple) == NULL)
-			return -1;
-		*result = tuple;
-	}
-	return 0;
+	tuple_ref(tuple);
+	int rc = txn_commit_stmt(txn, request);
+	if (rc == 0)
+		tuple_bless(tuple);
+	tuple_unref(tuple);
+	return rc;
  }
  
  void
diff --git a/src/box/errcode.h b/src/box/errcode.h
index a0759f8f4..e009524ad 100644
--- a/src/box/errcode.h
+++ b/src/box/errcode.h
@@ -138,7 +138,7 @@ struct errcode_record {
  	/* 83 */_(ER_ROLE_EXISTS,		"Role '%s' already exists") \
  	/* 84 */_(ER_CREATE_ROLE,		"Failed to create role '%s': %s") \
  	/* 85 */_(ER_INDEX_EXISTS,		"Index '%s' already exists") \
-	/* 86 */_(ER_TUPLE_REF_OVERFLOW,	"Tuple reference counter overflow") \
+	/* 86 */_(ER_UNUSED6,			"") \
  	/* 87 */_(ER_ROLE_LOOP,			"Granting role '%s' to role '%s' would create a loop") \
  	/* 88 */_(ER_GRANT,			"Incorrect grant arguments: %s") \
  	/* 89 */_(ER_PRIV_GRANTED,		"User '%s' already has %s access on %s '%s'") \
diff --git a/src/box/index.cc b/src/box/index.cc
index 3c62ec1cc..f992bc94c 100644
--- a/src/box/index.cc
+++ b/src/box/index.cc
@@ -220,8 +220,8 @@ box_index_random(uint32_t space_id, uint32_t index_id, uint32_t rnd,
  	/* No tx management, random() is for approximation anyway. */
  	if (index_random(index, rnd, result) != 0)
  		return -1;
-	if (*result != NULL && tuple_bless(*result) == NULL)
-		return -1;
+	if (*result != NULL)
+		tuple_bless(*result);
  	return 0;
  }
  
@@ -253,8 +253,8 @@ box_index_get(uint32_t space_id, uint32_t index_id, const char *key,
  	txn_commit_ro_stmt(txn);
  	/* Count statistics. */
  	rmean_collect(rmean_box, IPROTO_SELECT, 1);
-	if (*result != NULL && tuple_bless(*result) == NULL)
-		return -1;
+	if (*result != NULL)
+		tuple_bless(*result);
  	return 0;
  }
  
@@ -285,8 +285,8 @@ box_index_min(uint32_t space_id, uint32_t index_id, const char *key,
  		return -1;
  	}
  	txn_commit_ro_stmt(txn);
-	if (*result != NULL && tuple_bless(*result) == NULL)
-		return -1;
+	if (*result != NULL)
+		tuple_bless(*result);
  	return 0;
  }
  
@@ -317,8 +317,8 @@ box_index_max(uint32_t space_id, uint32_t index_id, const char *key,
  		return -1;
  	}
  	txn_commit_ro_stmt(txn);
-	if (*result != NULL && tuple_bless(*result) == NULL)
-		return -1;
+	if (*result != NULL)
+		tuple_bless(*result);
  	return 0;
  }
  
@@ -397,8 +397,8 @@ box_iterator_next(box_iterator_t *itr, box_tuple_t **result)
  	assert(result != NULL);
  	if (iterator_next(itr, result) != 0)
  		return -1;
-	if (*result != NULL && tuple_bless(*result) == NULL)
-		return -1;
+	if (*result != NULL)
+		tuple_bless(*result);
  	return 0;
  }
  
diff --git a/src/box/lua/tuple.c b/src/box/lua/tuple.c
index 80573313d..22fe69611 100644
--- a/src/box/lua/tuple.c
+++ b/src/box/lua/tuple.c
@@ -496,10 +496,7 @@ luaT_pushtuple(struct lua_State *L, box_tuple_t *tuple)
  		luaL_pushcdata(L, CTID_CONST_STRUCT_TUPLE_REF);
  	*ptr = tuple;
  	/* The order is important - first reference tuple, next set gc */
-	if (box_tuple_ref(tuple) != 0) {
-		luaT_error(L);
-		return;
-	}
+	box_tuple_ref(tuple);
  	lua_pushcfunction(L, lbox_tuple_gc);
  	luaL_setcdatagc(L, -2);
  }
diff --git a/src/box/port.c b/src/box/port.c
index 03f6be79d..9b6b8580c 100644
--- a/src/box/port.c
+++ b/src/box/port.c
@@ -45,8 +45,7 @@ port_tuple_add(struct port *base, struct tuple *tuple)
  	struct port_tuple *port = port_tuple(base);
  	struct port_tuple_entry *e;
  	if (port->size == 0) {
-		if (tuple_ref(tuple) != 0)
-			return -1;
+		tuple_ref(tuple);
  		e = &port->first_entry;
  		port->first = port->last = e;
  	} else {
@@ -55,10 +54,7 @@ port_tuple_add(struct port *base, struct tuple *tuple)
  			diag_set(OutOfMemory, sizeof(*e), "mempool_alloc", "e");
  			return -1;
  		}
-		if (tuple_ref(tuple) != 0) {
-			mempool_free(&port_tuple_entry_pool, e);
-			return -1;
-		}
+		tuple_ref(tuple);
  		port->last->next = e;
  		port->last = e;
  	}
diff --git a/src/box/tuple.c b/src/box/tuple.c
index 014f37406..5fc1c1283 100644
--- a/src/box/tuple.c
+++ b/src/box/tuple.c
@@ -48,6 +48,26 @@ enum {
  	OBJSIZE_MIN = 16,
  };
  
+/**
+ * Container for big reference counters. Contains array of big
+ * reference counters, size of this array and number of non-zero
+ * big reference counters. When reference counter of tuple becomes
+ * more than 32767, field refs of this tuple becomes index of big
+ * reference counter in big reference counter array and field
+ * is_bigref is set true. The moment big reference becomes equal
+ * 32767 it is set to 0, refs of the tuple becomes 32767 and
+ * is_bigref becomes false. Big reference counter can be equal to
+ * 0 or be more than 32767.
+ */
+static struct bigref_list {
+	/** Array of big reference counters. */
+	uint32_t *refs;
+	/** Number of non-zero elements in the array. */
+	uint16_t size;
+	/** Capacity of the array. */
+	uint16_t capacity;
+} bigref_list;
+
  static const double ALLOC_FACTOR = 1.05;
  
  /**
@@ -151,6 +171,13 @@ tuple_validate_raw(struct tuple_format *format, const char *tuple)
  	return 0;
  }
  
+/** Initialize big references container. */
+static inline void
+bigref_list_create()
+{
+	memset(&bigref_list, 0, sizeof(bigref_list));
+}
+
  /**
   * Incremented on every snapshot and is used to distinguish tuples
   * which were created after start of a snapshot (these tuples can
@@ -211,6 +238,8 @@ tuple_init(field_name_hash_f hash)
  
  	box_tuple_last = NULL;
  
+	bigref_list_create();
+
  	if (coll_id_cache_init() != 0)
  		return -1;
  
@@ -244,6 +273,131 @@ tuple_arena_create(struct slab_arena *arena, struct quota *quota,
  	}
  }
  
+enum {
+	BIGREF_FACTOR = 2,
+	BIGREF_MAX = UINT32_MAX,
+	BIGREF_MIN_CAPACITY = 16,
+	/**
+	 * Only 15 bits are available for bigref list index in
+	 * struct tuple.
+	 */
+	BIGREF_MAX_CAPACITY = UINT16_MAX >> 1
+};
+
+/** Destroy big references and free memory that was allocated. */
+static inline void
+bigref_list_destroy()
+{
+	free(bigref_list.refs);
+	bigref_list_create();
+}
+
+/**
+ * Return index for new big reference counter and allocate memory
+ * if needed.
+ * @retval index for new big reference counter.
+ */
+static inline uint16_t
+bigref_list_new_index()
+{
+	if (bigref_list.size < bigref_list.capacity) {
+		uint16_t vacant_index = 0;
+		while (bigref_list.refs[vacant_index] != 0)
+			++vacant_index;
+		return vacant_index;
+	}
+	/* Extend the array. */
+	uint16_t capacity = bigref_list.capacity;
+	if (capacity == 0)
+		capacity = BIGREF_MIN_CAPACITY;
+	else if (capacity < BIGREF_MAX_CAPACITY)
+		capacity = MIN(capacity * BIGREF_FACTOR, BIGREF_MAX_CAPACITY);
+	else
+		panic("Too many big references");
+	uint32_t *refs = (uint32_t *) realloc(bigref_list.refs, capacity *
+					      sizeof(*bigref_list.refs));
+	if (refs == NULL) {
+		panic("failed to reallocate %zu bytes: Cannot allocate "\
+		      "memory.", capacity * sizeof(*bigref_list.refs));
+	}
+	bigref_list.refs = refs;
+	memset(bigref_list.refs + bigref_list.capacity, 0, capacity -
+	       bigref_list.capacity);
+	bigref_list.capacity = capacity;
+	return bigref_list.size++;
+}
+
+void
+tuple_ref_slow(struct tuple *tuple)
+{
+	assert(tuple->is_bigref || tuple->refs == TUPLE_REF_MAX);
+	if (! tuple->is_bigref) {
+		tuple->ref_index = bigref_list_new_index();
+		tuple->is_bigref = true;
+		bigref_list.refs[tuple->ref_index] = TUPLE_REF_MAX;
+	} else if (bigref_list.refs[tuple->ref_index] == BIGREF_MAX) {
+		panic("Tuple big reference counter overflow");
+	}
+	bigref_list.refs[tuple->ref_index]++;
+}
+
+/**
+ * Try to decrease allocated memory if it is possible. Free memory
+ * when size == 0.
+ */
+static inline void
+bigref_list_delete_index(uint16_t index)
+{
+	bigref_list.refs[index] = 0;
+	if (--bigref_list.size == 0) {
+		bigref_list_destroy();
+		return;
+	}
+	if (bigref_list.capacity == BIGREF_MIN_CAPACITY ||
+	    bigref_list.size > bigref_list.capacity / BIGREF_FACTOR)
+		return;
+
+	uint16_t top_index = bigref_list.capacity - 1;
+	while (bigref_list.refs[top_index] == 0)
+		top_index--;
+
+	uint16_t needed_capacity = top_index + 1;
+	if (needed_capacity < BIGREF_MIN_CAPACITY)
+		needed_capacity = BIGREF_MIN_CAPACITY;
+	if (needed_capacity > bigref_list.capacity / BIGREF_FACTOR)
+		return;
+	/* Round up capacity to the next highest power of 2. */
+	assert(sizeof(needed_capacity) == sizeof(uint16_t));
+	needed_capacity--;
+	needed_capacity |= needed_capacity >> 1;
+	needed_capacity |= needed_capacity >> 2;
+	needed_capacity |= needed_capacity >> 4;
+	needed_capacity |= needed_capacity >> 8;
+	assert(needed_capacity < UINT16_MAX);
+	needed_capacity++;
+	uint32_t *refs =
+		(uint32_t *) realloc(bigref_list.refs, needed_capacity *
+				     sizeof(*bigref_list.refs));
+	if (refs == NULL) {
+		panic("failed to reallocate %zu bytes: Cannot allocate "\
+		      "memory.", needed_capacity * sizeof(*bigref_list.refs));
+	}
+	bigref_list.refs = refs;
+	bigref_list.capacity = needed_capacity;
+}
+
+void
+tuple_unref_slow(struct tuple *tuple)
+{
+	assert(tuple->is_bigref &&
+	       bigref_list.refs[tuple->ref_index] > TUPLE_REF_MAX);
+	if(--bigref_list.refs[tuple->ref_index] == TUPLE_REF_MAX) {
+		bigref_list_delete_index(tuple->ref_index);
+		tuple->ref_index = TUPLE_REF_MAX;
+		tuple->is_bigref = false;
+	}
+}
+
  void
  tuple_arena_destroy(struct slab_arena *arena)
  {
@@ -265,6 +419,8 @@ tuple_free(void)
  	tuple_format_free();
  
  	coll_id_cache_destroy();
+
+	bigref_list_destroy();
  }
  
  box_tuple_format_t *
@@ -288,7 +444,8 @@ int
  box_tuple_ref(box_tuple_t *tuple)
  {
  	assert(tuple != NULL);
-	return tuple_ref(tuple);
+	tuple_ref(tuple);
+	return 0;
  }
  
  void
@@ -357,10 +514,7 @@ box_tuple_iterator(box_tuple_t *tuple)
  			 "mempool", "new slab");
  		return NULL;
  	}
-	if (tuple_ref(tuple) != 0) {
-		mempool_free(&tuple_iterator_pool, it);
-		return NULL;
-	}
+	tuple_ref(tuple);
  	tuple_rewind(it, tuple);
  	return it;
  }
@@ -451,7 +605,6 @@ box_tuple_new(box_tuple_format_t *format, const char *data, const char *end)
  	struct tuple *ret = tuple_new(format, data, end);
  	if (ret == NULL)
  		return NULL;
-	/* Can't fail on zero refs. */
  	return tuple_bless(ret);
  }
  
diff --git a/src/box/tuple.h b/src/box/tuple.h
index e2384dda0..14dbd4094 100644
--- a/src/box/tuple.h
+++ b/src/box/tuple.h
@@ -105,8 +105,7 @@ typedef struct tuple box_tuple_t;
   * tuple will leak.
   *
   * \param tuple a tuple
- * \retval -1 on error (check box_error_last())
- * \retval 0 on success
+ * \retval 0 always
   * \sa box_tuple_unref()
   */
  int
@@ -269,8 +268,7 @@ box_tuple_next(box_tuple_iterator_t *it);
   * Use box_tuple_format_default() to create space-independent tuple.
   * \param data tuple data in MsgPack Array format ([field1, field2, ...]).
   * \param end the end of \a data
- * \retval NULL on out of memory
- * \retval tuple otherwise
+ * \retval tuple
   * \pre data, end is valid MsgPack Array
   * \sa \code box.tuple.new(data) \endcode
   */
@@ -307,9 +305,17 @@ box_tuple_upsert(const box_tuple_t *tuple, const char *expr, const
   */
  struct PACKED tuple
  {
-	/** reference counter */
-	uint16_t refs;
-	/** format identifier */
+	union {
+		/** Reference counter. */
+		uint16_t refs;
+		struct {
+			/** Index of big reference counter. */
+			uint16_t ref_index : 15;
+			/** Big reference flag. */
+			bool is_bigref : 1;
+		};
+	};
+	/** Format identifier. */
  	uint16_t format_id;
  	/**
  	 * Length of the MessagePack data in raw part of the
@@ -774,25 +780,35 @@ tuple_field_uuid(const struct tuple *tuple, int fieldno,
  	return 0;
  }
  
-enum { TUPLE_REF_MAX = UINT16_MAX };
+enum { TUPLE_REF_MAX = UINT16_MAX >> 1 };
+
+/**
+ * Increase tuple big reference counter.
+ * @param tuple Tuple to reference.
+ */
+void
+tuple_ref_slow(struct tuple *tuple);
  
  /**
   * Increment tuple reference counter.
   * @param tuple Tuple to reference.
- * @retval  0 Success.
- * @retval -1 Too many refs error.
   */
-static inline int
+static inline void
  tuple_ref(struct tuple *tuple)
  {
-	if (tuple->refs + 1 > TUPLE_REF_MAX) {
-		diag_set(ClientError, ER_TUPLE_REF_OVERFLOW);
-		return -1;
-	}
-	tuple->refs++;
-	return 0;
+	if (unlikely(tuple->refs >= TUPLE_REF_MAX))
+		tuple_ref_slow(tuple);
+	else
+		tuple->refs++;
  }
  
+/**
+ * Decrease tuple big reference counter.
+ * @param tuple Tuple to reference.
+ */
+void
+tuple_unref_slow(struct tuple *tuple);
+
  /**
   * Decrement tuple reference counter. If it has reached zero, free the tuple.
   *
@@ -802,10 +818,9 @@ static inline void
  tuple_unref(struct tuple *tuple)
  {
  	assert(tuple->refs - 1 >= 0);
-
-	tuple->refs--;
-
-	if (tuple->refs == 0)
+	if (unlikely(tuple->is_bigref))
+		tuple_unref_slow(tuple);
+	else if (--tuple->refs == 0)
  		tuple_delete(tuple);
  }
  
@@ -813,25 +828,18 @@ extern struct tuple *box_tuple_last;
  
  /**
   * Convert internal `struct tuple` to public `box_tuple_t`.
- * \retval tuple on success
- * \retval NULL on error, check diag
+ * \retval tuple
   * \post \a tuple ref counted until the next call.
- * \post tuple_ref() doesn't fail at least once
   * \sa tuple_ref
   */
  static inline box_tuple_t *
  tuple_bless(struct tuple *tuple)
  {
  	assert(tuple != NULL);
-	/* Ensure tuple can be referenced at least once after return */
-	if (tuple->refs + 2 > TUPLE_REF_MAX) {
-		diag_set(ClientError, ER_TUPLE_REF_OVERFLOW);
-		return NULL;
-	}
-	tuple->refs++;
+	tuple_ref(tuple);
  	/* Remove previous tuple */
  	if (likely(box_tuple_last != NULL))
-		tuple_unref(box_tuple_last); /* do not throw */
+		tuple_unref(box_tuple_last);
  	/* Remember current tuple */
  	box_tuple_last = tuple;
  	return tuple;
@@ -849,41 +857,6 @@ tuple_to_buf(const struct tuple *tuple, char *buf, size_t size);
  #include "tuple_update.h"
  #include "errinj.h"
  
-/**
- * \copydoc tuple_ref()
- * \throws if overflow detected.
- */
-static inline void
-tuple_ref_xc(struct tuple *tuple)
-{
-	if (tuple_ref(tuple))
-		diag_raise();
-}
-
-/**
- * \copydoc tuple_bless
- * \throw ER_TUPLE_REF_OVERFLOW
- */
-static inline box_tuple_t *
-tuple_bless_xc(struct tuple *tuple)
-{
-	box_tuple_t *blessed = tuple_bless(tuple);
-	if (blessed == NULL)
-		diag_raise();
-	return blessed;
-}
-
-/** Make tuple references exception-friendly in absence of @finally. */
-struct TupleRefNil {
-	struct tuple *tuple;
-	TupleRefNil (struct tuple *arg) :tuple(arg)
-	{ if (tuple) tuple_ref_xc(tuple); }
-	~TupleRefNil() { if (tuple) tuple_unref(tuple); }
-
-	TupleRefNil(const TupleRefNil&) = delete;
-	void operator=(const TupleRefNil&) = delete;
-};
-
  /* @copydoc tuple_field_with_type() */
  static inline const char *
  tuple_field_with_type_xc(const struct tuple *tuple, uint32_t fieldno,
diff --git a/src/box/vinyl.c b/src/box/vinyl.c
index f0d26874e..dc0d02054 100644
--- a/src/box/vinyl.c
+++ b/src/box/vinyl.c
@@ -3822,7 +3822,6 @@ vinyl_iterator_primary_next(struct iterator *base, struct tuple **ret)
  	assert(base->next = vinyl_iterator_primary_next);
  	struct vinyl_iterator *it = (struct vinyl_iterator *)base;
  	assert(it->lsm->index_id == 0);
-	struct tuple *tuple;
  
  	if (it->tx == NULL) {
  		diag_set(ClientError, ER_CURSOR_NO_TRANSACTION);
@@ -3833,18 +3832,15 @@ vinyl_iterator_primary_next(struct iterator *base, struct tuple **ret)
  		goto fail;
  	}
  
-	if (vy_read_iterator_next(&it->iterator, &tuple) != 0)
+	if (vy_read_iterator_next(&it->iterator, ret) != 0)
  		goto fail;
-
-	if (tuple == NULL) {
+	if (*ret == NULL) {
  		/* EOF. Close the iterator immediately. */
  		vinyl_iterator_close(it);
-		*ret = NULL;
-		return 0;
+	} else {
+		tuple_bless(*ret);
  	}
-	*ret = tuple_bless(tuple);
-	if (*ret != NULL)
-		return 0;
+	return 0;
  fail:
  	vinyl_iterator_close(it);
  	return -1;
@@ -3890,11 +3886,10 @@ next:
  	 * Note, there's no need in vy_tx_track() as the
  	 * tuple is already tracked in the secondary index.
  	 */
-	struct tuple *full_tuple;
  	if (vy_point_lookup(it->lsm->pk, it->tx, vy_tx_read_view(it->tx),
-			    tuple, &full_tuple) != 0)
+			    tuple, ret) != 0)
  		goto fail;
-	if (full_tuple == NULL) {
+	if (*ret == NULL) {
  		/*
  		 * All indexes of a space must be consistent, i.e.
  		 * if a tuple is present in one index, it must be
@@ -3908,10 +3903,9 @@ next:
  			 vy_lsm_name(it->lsm), vy_stmt_str(tuple));
  		goto next;
  	}
-	*ret = tuple_bless(full_tuple);
-	tuple_unref(full_tuple);
-	if (*ret != NULL)
-		return 0;
+	tuple_bless(*ret);
+	tuple_unref(*ret);
+	return 0;
  fail:
  	vinyl_iterator_close(it);
  	return -1;
@@ -3997,16 +3991,12 @@ vinyl_index_get(struct index *index, const char *key,
  	const struct vy_read_view **rv = (tx != NULL ? vy_tx_read_view(tx) :
  					  &env->xm->p_global_read_view);
  
-	struct tuple *tuple;
-	if (vy_lsm_full_by_key(lsm, tx, rv, key, part_count, &tuple) != 0)
+	if (vy_lsm_full_by_key(lsm, tx, rv, key, part_count, ret) != 0)
  		return -1;
-
-	if (tuple != NULL) {
-		*ret = tuple_bless(tuple);
-		tuple_unref(tuple);
-		return *ret == NULL ? -1 : 0;
+	if (*ret != NULL) {
+		tuple_bless(*ret);
+		tuple_unref(*ret);
  	}
-	*ret = NULL;
  	return 0;
  }
  
diff --git a/test/box/misc.result b/test/box/misc.result
index 8f94f5513..f7703ba8d 100644
--- a/test/box/misc.result
+++ b/test/box/misc.result
@@ -332,7 +332,6 @@ t;
    - 'box.error.UNKNOWN_UPDATE_OP : 28'
    - 'box.error.WRONG_COLLATION_OPTIONS : 151'
    - 'box.error.CURSOR_NO_TRANSACTION : 80'
-  - 'box.error.TUPLE_REF_OVERFLOW : 86'
    - 'box.error.ALTER_SEQUENCE : 143'
    - 'box.error.INVALID_XLOG_NAME : 75'
    - 'box.error.SAVEPOINT_EMPTY_TX : 60'
@@ -360,7 +359,7 @@ t;
    - 'box.error.VINYL_MAX_TUPLE_SIZE : 139'
    - 'box.error.LOAD_FUNCTION : 99'
    - 'box.error.INVALID_XLOG : 74'
-  - 'box.error.PRIV_NOT_GRANTED : 91'
+  - 'box.error.READ_VIEW_ABORTED : 130'
    - 'box.error.TRANSACTION_CONFLICT : 97'
    - 'box.error.GUEST_USER_PASSWORD : 96'
    - 'box.error.PROC_C : 102'
@@ -405,7 +404,7 @@ t;
    - 'box.error.injection : table: <address>
    - 'box.error.NULLABLE_MISMATCH : 153'
    - 'box.error.LAST_DROP : 15'
-  - 'box.error.NO_SUCH_ROLE : 82'
+  - 'box.error.TUPLE_FORMAT_LIMIT : 16'
    - 'box.error.DECOMPRESSION : 124'
    - 'box.error.CREATE_SEQUENCE : 142'
    - 'box.error.CREATE_USER : 43'
@@ -414,66 +413,66 @@ t;
    - 'box.error.SEQUENCE_OVERFLOW : 147'
    - 'box.error.SYSTEM : 115'
    - 'box.error.KEY_PART_IS_TOO_LONG : 118'
-  - 'box.error.TUPLE_FORMAT_LIMIT : 16'
-  - 'box.error.BEFORE_REPLACE_RET : 53'
+  - 'box.error.INJECTION : 8'
+  - 'box.error.INVALID_MSGPACK : 20'
    - 'box.error.NO_SUCH_SAVEPOINT : 61'
    - 'box.error.TRUNCATE_SYSTEM_SPACE : 137'
    - 'box.error.VY_QUOTA_TIMEOUT : 135'
    - 'box.error.WRONG_INDEX_OPTIONS : 108'
    - 'box.error.INVALID_VYLOG_FILE : 133'
    - 'box.error.INDEX_FIELD_COUNT_LIMIT : 127'
-  - 'box.error.READ_VIEW_ABORTED : 130'
+  - 'box.error.PRIV_NOT_GRANTED : 91'
    - 'box.error.USER_MAX : 56'
-  - 'box.error.PROTOCOL : 104'
+  - 'box.error.BEFORE_REPLACE_RET : 53'
    - 'box.error.TUPLE_NOT_ARRAY : 22'
    - 'box.error.KEY_PART_COUNT : 31'
    - 'box.error.ALTER_SPACE : 12'
    - 'box.error.ACTIVE_TRANSACTION : 79'
    - 'box.error.EXACT_FIELD_COUNT : 38'
    - 'box.error.DROP_SEQUENCE : 144'
-  - 'box.error.INVALID_MSGPACK : 20'
    - 'box.error.MORE_THAN_ONE_TUPLE : 41'
-  - 'box.error.RTREE_RECT : 101'
-  - 'box.error.SUB_STMT_MAX : 121'
+  - 'box.error.UPSERT_UNIQUE_SECONDARY_KEY : 105'
    - 'box.error.UNKNOWN_REQUEST_TYPE : 48'
-  - 'box.error.SPACE_EXISTS : 10'
+  - 'box.error.SUB_STMT_MAX : 121'
    - 'box.error.PROC_LUA : 32'
+  - 'box.error.SPACE_EXISTS : 10'
    - 'box.error.ROLE_NOT_GRANTED : 92'
+  - 'box.error.UNSUPPORTED : 5'
    - 'box.error.NO_SUCH_SPACE : 36'
    - 'box.error.WRONG_INDEX_PARTS : 107'
-  - 'box.error.DROP_SPACE : 11'
    - 'box.error.MIN_FIELD_COUNT : 39'
    - 'box.error.REPLICASET_UUID_MISMATCH : 63'
    - 'box.error.UPDATE_FIELD : 29'
+  - 'box.error.INDEX_EXISTS : 85'
    - 'box.error.COMPRESSION : 119'
    - 'box.error.INVALID_ORDER : 68'
-  - 'box.error.INDEX_EXISTS : 85'
    - 'box.error.SPLICE : 25'
    - 'box.error.UNKNOWN : 0'
+  - 'box.error.IDENTIFIER : 70'
    - 'box.error.DROP_PRIMARY_KEY : 17'
    - 'box.error.NULLABLE_PRIMARY : 152'
    - 'box.error.NO_SUCH_SEQUENCE : 145'
    - 'box.error.RELOAD_CFG : 58'
    - 'box.error.INVALID_UUID : 64'
-  - 'box.error.INJECTION : 8'
+  - 'box.error.DROP_SPACE : 11'
    - 'box.error.TIMEOUT : 78'
-  - 'box.error.IDENTIFIER : 70'
    - 'box.error.ITERATOR_TYPE : 72'
    - 'box.error.REPLICA_MAX : 73'
+  - 'box.error.NO_SUCH_ROLE : 82'
    - 'box.error.MISSING_REQUEST_FIELD : 69'
    - 'box.error.MISSING_SNAPSHOT : 93'
    - 'box.error.WRONG_SPACE_OPTIONS : 111'
    - 'box.error.READONLY : 7'
-  - 'box.error.UNSUPPORTED : 5'
    - 'box.error.UPDATE_INTEGER_OVERFLOW : 95'
+  - 'box.error.RTREE_RECT : 101'
    - 'box.error.NO_CONNECTION : 77'
    - 'box.error.INVALID_XLOG_ORDER : 76'
-  - 'box.error.UPSERT_UNIQUE_SECONDARY_KEY : 105'
-  - 'box.error.ROLLBACK_IN_SUB_STMT : 123'
    - 'box.error.WRONG_SCHEMA_VERSION : 109'
-  - 'box.error.UNSUPPORTED_INDEX_FEATURE : 112'
-  - 'box.error.INDEX_PART_TYPE_MISMATCH : 24'
+  - 'box.error.ROLLBACK_IN_SUB_STMT : 123'
+  - 'box.error.PROTOCOL : 104'
    - 'box.error.INVALID_XLOG_TYPE : 125'
+  - 'box.error.INDEX_PART_TYPE_MISMATCH : 24'
+  - 'box.error.UNSUPPORTED_INDEX_FEATURE : 112'
  ...
  test_run:cmd("setopt delimiter ''");
  ---
diff --git a/test/box/select.result b/test/box/select.result
index 4aed70630..6e6ccade1 100644
--- a/test/box/select.result
+++ b/test/box/select.result
@@ -619,6 +619,11 @@ collectgarbage('collect')
  ---
  - 0
  ...
+-- gh-3224 resurrect tuple bigrefs
+collectgarbage('stop')
+---
+- 0
+...
  s = box.schema.space.create('select', { temporary = true })
  ---
  ...
@@ -628,22 +633,37 @@ index = s:create_index('primary', { type = 'tree' })
  a = s:insert{0}
  ---
  ...
-lots_of_links = {}
+lots_of_links = setmetatable({}, {__mode = 'v'})
+---
+...
+ref_count = 0
+---
+...
+while (ref_count < 100000) do table.insert(lots_of_links, s:get{0}) ref_count = ref_count + 1 end
  ---
  ...
+ref_count
+---
+- 100000
+...
  ref_count = 0
  ---
  ...
-while (true) do table.insert(lots_of_links, s:get{0}) ref_count = ref_count + 1 end
+for k, v in pairs(lots_of_links) do ref_count = ref_count + 1 end
  ---
-- error: Tuple reference counter overflow
  ...
  ref_count
  ---
-- 65531
+- 100000
+...
+-- check that tuples are deleted after gc is activated
+collectgarbage('collect')
+---
+- 0
  ...
-lots_of_links = {}
+lots_of_links
  ---
+- []
  ...
  s:drop()
  ---
diff --git a/test/box/select.test.lua b/test/box/select.test.lua
index 54c2ecc1c..f15c6e275 100644
--- a/test/box/select.test.lua
+++ b/test/box/select.test.lua
@@ -124,12 +124,21 @@ test.random(s.index[0], 48)
  s:drop()
  
  collectgarbage('collect')
+
+-- gh-3224 resurrect tuple bigrefs
+
+collectgarbage('stop')
  s = box.schema.space.create('select', { temporary = true })
  index = s:create_index('primary', { type = 'tree' })
  a = s:insert{0}
-lots_of_links = {}
+lots_of_links = setmetatable({}, {__mode = 'v'})
  ref_count = 0
-while (true) do table.insert(lots_of_links, s:get{0}) ref_count = ref_count + 1 end
+while (ref_count < 100000) do table.insert(lots_of_links, s:get{0}) ref_count = ref_count + 1 end
  ref_count
-lots_of_links = {}
+ref_count = 0
+for k, v in pairs(lots_of_links) do ref_count = ref_count + 1 end
+ref_count
+-- check that tuples are deleted after gc is activated
+collectgarbage('collect')
+lots_of_links
  s:drop()