[tarantool-patches] Re: [PATCH v2 1/2] box: create bigrefs for tuples

[Imeev Mergen <imeevma@tarantool.org>]

On 06/08/2018 12:24 AM, Vladislav Shpilevoy wrote:
> Hello. Thanks for the patch! I have pushed some minor fixes. Look at
> them, squash. See the rest 3 comments below.
>
>> diff --git a/test/unit/tuple_bigref.c b/test/unit/tuple_bigref.c
>> new file mode 100644
>> index 0000000..fd166fd
>> --- /dev/null
>> +++ b/test/unit/tuple_bigref.c
>> @@ -0,0 +1,156 @@
>> +#include "vy_iterators_helper.h"
>> +#include "memory.h"
>> +#include "fiber.h"
>> +#include "unit.h"
>> +#include <msgpuck.h>
>> +#include "trivia/util.h"
>> +
>> +enum
>> +{
>> +    BIGREF_DIFF = 10,
>> +    BIGREF_COUNT = 100003,
>
> 1. Please, reduce the count to 70k for example. There is no
> difference 100k or 70k for bigref list, but the test will be
> faster.
Done.
>
>> +    BIGREF_CAPACITY = 107,
>> +};
>> +
>> +/**
>> + * This test checks that indexes are given as intended.
>
> 2. Actually this test works exactly like the first one. See the
> comments below.
>> + */
>> +static int
>> +test_bigrefs_3()
>> +{
>> +    struct tuple **tuples = (struct tuple **) malloc(BIGREF_CAPACITY *
>> +                             sizeof(*tuples));
>> +    for(int i = 0; i < BIGREF_CAPACITY; ++i) {
>> +        tuples[i] = create_tuple();
>> +        tuple_ref(tuples[i]);
>> +    }
>> +    for(int i = 0; i < BIGREF_CAPACITY; ++i) {
>> +        assert(tuples[i]->refs == 1);
>> +        for(int j = 1; j < BIGREF_COUNT; ++j)
>> +            box_tuple_ref(tuples[i]);
>> +        assert(tuples[i]->is_bigref);
>> +        if(i % BIGREF_DIFF == 0) {
>> +            for(int j = 1; j < BIGREF_COUNT; ++j)
>> +                box_tuple_unref(tuples[i]);
>> +        }
>
> 3. Here when i % BIGREF_DIFF, you had added the tuple to bigref list,
> and then have deleted it immediately. So the list has no gaps and works
> exactly like in the first test.
>
> Please, rework this test to test a list with gaps. You should fill it,
> then remove some of tuples, for example, each BIGREF_DIFF, and check,
> that other tuples are not destroyed. And that new tuples occupy the
> gaps.
Changed test_bigrefs_3, added gaps in creating and in destroying. New 
received
indexes should be equal to index of tuple with refilled refs.
> And please, use gcov to check coverage of tuple bigrefs. I have run
> gcov, and saw this:
>
>         -:  362:static inline void
>         -:  363:bigref_list_delete_index(uint16_t index)
>         -:  364:{
>       648:  365:    bigref_list.refs[index] = 0;
>       648:  366:    if (--bigref_list.size == 0) {
>        15:  367:        bigref_list_reset();
>        15:  368:        return;
>         -:  369:    }
>         -:  370:    /* Drop the 'take' hint. */
>       633:  371:    bigref_list.hint_index_to_take = 0;
>      1263:  372:    if (bigref_list.capacity == BIGREF_MIN_CAPACITY ||
>       630:  373:        bigref_list.size > bigref_list.capacity / 
> BIGREF_FACTOR)
>       249:  374:        return;
>         -:  375:
>       384:  376:    uint16_t top_index = bigref_list.hint_index_to_free;
>      1086:  377:    while (bigref_list.refs[top_index] == 0)
>       159:  378:        top_index--;
>       384:  379:    bigref_list.hint_index_to_free = top_index;
>         -:  380:
>       384:  381:    uint16_t needed_capacity = top_index + 1;
>       384:  382:    if (needed_capacity < BIGREF_MIN_CAPACITY)
>     #####:  383:        needed_capacity = BIGREF_MIN_CAPACITY;
>       384:  384:    if (needed_capacity > bigref_list.capacity / 
> BIGREF_FACTOR)
>       384:  385:        return;
>         -:  386:    /* Round up capacity to the next highest power of 
> 2. */
>         -:  387:    assert(sizeof(needed_capacity) == sizeof(uint16_t));
>     #####:  388:    needed_capacity--;
>     #####:  389:    needed_capacity |= needed_capacity >> 1;
>     #####:  390:    needed_capacity |= needed_capacity >> 2;
>     #####:  391:    needed_capacity |= needed_capacity >> 4;
>     #####:  392:    needed_capacity |= needed_capacity >> 8;
>     #####:  393:    assert(needed_capacity < UINT16_MAX);
>     #####:  394:    needed_capacity++;
>     #####:  395:    uint32_t *refs =
>     #####:  396:        (uint32_t *) realloc(bigref_list.refs, 
> needed_capacity *
>         -:  397:                     sizeof(*bigref_list.refs));
>     #####:  398:    if (refs == NULL) {
>     #####:  399:        panic("failed to reallocate %zu bytes: Cannot 
> allocate "\
>         -:  400:              "memory.", needed_capacity * 
> sizeof(*bigref_list.refs));
>         -:  401:    }
>     #####:  402:    bigref_list.refs = refs;
>     #####:  403:    bigref_list.capacity = needed_capacity;
>       648:  404:}
>
Done. All lines but the ones that contain panic() are used.
>
> ##### means this line had never been executed. You should write such a 
> test, that
> will cover these lines.
>
> To use gcov you can build Tarantool with ENABLE_GCOV:
>
>     cmake . -DENABLE_GCOV=1
>     make -j
>
> Then you run the test:
>
>     ./test/unit/tuple_bigref.test
>
> Then you convert .gcda/.gcno files to .gcov files:
>
>     gcov src/box/tuple.c -o src/box/CMakeFiles/tuple.dir/tuple.c.gcno
>
> Now tuple.c.gcov stores the coverage info.
> These commands work on Mac. Maybe on Linux it differs. If cmake 
> ENABLE_GCOV
> does not work, then try this:
>
>     @@ -4,10 +4,7 @@ set(ENABLE_GCOV_DEFAULT OFF)
>      option(ENABLE_GCOV "Enable integration with gcov, a code coverage 
> program" ${ENABLE_GCOV_DEFAULT})
>
>      if (ENABLE_GCOV)
>     -    if (NOT HAVE_GCOV)
>     -    message (FATAL_ERROR
>     -         "ENABLE_GCOV option requested but gcov library is not 
> found")
>     -    endif()
>
> and run cmake again.
>

commit d7e3481f71882ff02f08f3f66175e6bb3830b6e0
Author: Mergen Imeev <imeevma@gmail.com>
Date: Mon, 28 May 2018 19:17:51 +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 c728a4c..4257861 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 a0759f8..e009524 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 3c62ec1..f992bc9 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 8057331..22fe696 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 03f6be7..9b6b858 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 014f374..68540f4 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 +273,132 @@ 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_reset()
+{
+    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;
+        ++bigref_list.size;
+        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) * sizeof(*bigref_list.refs));
+    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_reset();
+        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 +420,8 @@ tuple_free(void)
      tuple_format_free();

      coll_id_cache_destroy();
+
+    bigref_list_reset();
  }

  box_tuple_format_t *
@@ -288,7 +445,8 @@ int
  box_tuple_ref(box_tuple_t *tuple)
  {
      assert(tuple != NULL);
-    return tuple_ref(tuple);
+    tuple_ref(tuple);
+    return 0;
  }

  void
@@ -357,10 +515,7 @@ 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 +606,6 @@ 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 e2384dd..14dbd40 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
@@ -774,26 +780,36 @@ 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.
   *
   * @pre tuple->refs + count >= 0
@@ -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 f0d2687..dc0d020 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 8f94f55..f7703ba 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 4aed706..b3ee6cd 100644
--- a/test/box/select.result
+++ b/test/box/select.result
@@ -619,31 +619,62 @@ collectgarbage('collect')
  ---
  - 0
  ...
+-- gh-3224 resurrect tuple bigrefs
+collectgarbage('stop')
+---
+- 0
+...
  s = box.schema.space.create('select', { temporary = true })
  ---
  ...
  index = s:create_index('primary', { type = 'tree' })
  ---
  ...
-a = s:insert{0}
+_ = s:insert{0}
+---
+...
+_ = s:insert{1}
+---
+...
+_ = s:insert{2}
+---
+...
+_ = s:insert{3}
+---
+...
+lots_of_links = setmetatable({}, {__mode = 'v'})
  ---
  ...
-lots_of_links = {}
+i = 0
+---
+...
+while (i < 33000) do table.insert(lots_of_links, s:get{0}) i = i + 1 end
+---
+...
+while (i < 66000) do table.insert(lots_of_links, s:get{1}) i = i + 1 end
+---
+...
+while (i < 100000) do table.insert(lots_of_links, s:get{2}) i = i + 1 end
  ---
  ...
  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
  ...
-lots_of_links = {}
+-- check that tuples are deleted after gc is activated
+collectgarbage('collect')
  ---
+- 0
+...
+lots_of_links
+---
+- []
  ...
  s:drop()
  ---
diff --git a/test/box/select.test.lua b/test/box/select.test.lua
index 54c2ecc..3400bda 100644
--- a/test/box/select.test.lua
+++ b/test/box/select.test.lua
@@ -124,12 +124,25 @@ 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 = {}
+_ = s:insert{0}
+_ = s:insert{1}
+_ = s:insert{2}
+_ = s:insert{3}
+lots_of_links = setmetatable({}, {__mode = 'v'})
+i = 0
+while (i < 33000) do table.insert(lots_of_links, s:get{0}) i = i + 1 end
+while (i < 66000) do table.insert(lots_of_links, s:get{1}) i = i + 1 end
+while (i < 100000) do table.insert(lots_of_links, s:get{2}) i = i + 1 end
  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
  ref_count
-lots_of_links = {}
+-- check that tuples are deleted after gc is activated
+collectgarbage('collect')
+lots_of_links
  s:drop()
diff --git a/test/unit/CMakeLists.txt b/test/unit/CMakeLists.txt
index dbc02cd..aef5316 100644
--- a/test/unit/CMakeLists.txt
+++ b/test/unit/CMakeLists.txt
@@ -192,3 +192,6 @@ target_link_libraries(vy_cache.test 
${ITERATOR_TEST_LIBS})

  add_executable(coll.test coll.cpp)
  target_link_libraries(coll.test core unit ${ICU_LIBRARIES} misc)
+
+add_executable(tuple_bigref.test tuple_bigref.c)
+target_link_libraries(tuple_bigref.test tuple unit)
diff --git a/test/unit/tuple_bigref.c b/test/unit/tuple_bigref.c
new file mode 100644
index 0000000..a24ab91
--- /dev/null
+++ b/test/unit/tuple_bigref.c
@@ -0,0 +1,174 @@
+#include "vy_iterators_helper.h"
+#include "memory.h"
+#include "fiber.h"
+#include "unit.h"
+#include <msgpuck.h>
+#include "trivia/util.h"
+
+enum {
+    BIGREF_DIFF = 10,
+    BIGREF_COUNT = 70003,
+    BIGREF_CAPACITY = 107,
+};
+
+static char tuple_buf[64];
+static char *tuple_end = tuple_buf;
+
+/**
+ * This function creates new tuple with refs == 1.
+ */
+static inline struct tuple *
+create_tuple()
+{
+    struct tuple *ret =
+        tuple_new(box_tuple_format_default(), tuple_buf, tuple_end);
+    tuple_ref(ret);
+    return ret;
+}
+
+/**
+ * This test performs overall check of bigrefs.
+ * What it checks:
+ * 1) Till refs <= TUPLE_REF_MAX it shows number of refs
+ * of tuple and it isn't a bigref.
+ * 2) When refs > TUPLE_REF_MAX first 15 bits of it becomes
+ * index of bigref and the last bit becomes true which
+ * shows that it is bigref.
+ * 3) Each of tuple has its own number of refs, but all
+ * these numbers more than it is needed for getting a bigref.
+ * 4) Indexes of bigrefs are given sequentially.
+ * 5) After some tuples are sequentially deleted all of
+ * others bigrefs are fine. In this test BIGREF_CAPACITY
+ * tuples created and each of their ref counter increased
+ * to (BIGREF_COUNT - index of tuple). Tuples are created
+ * consistently.
+ */
+static int
+test_bigrefs_1()
+{
+    struct tuple **tuples = (struct tuple **) malloc(BIGREF_CAPACITY *
+                             sizeof(*tuples));
+    for(int i = 0; i < BIGREF_CAPACITY; ++i)
+        tuples[i] = create_tuple();
+    for(int i = 0; i < BIGREF_CAPACITY; ++i) {
+        assert(tuples[i]->refs == 1);
+        for(int j = 1; j < TUPLE_REF_MAX; ++j)
+            tuple_ref(tuples[i]);
+        assert(! tuples[i]->is_bigref);
+        tuple_ref(tuples[i]);
+        assert(tuples[i]->is_bigref);
+        for(int j = TUPLE_REF_MAX + 1; j < BIGREF_COUNT - i; ++j)
+            tuple_ref(tuples[i]);
+        assert(tuples[i]->is_bigref && tuples[i]->ref_index == i);
+    }
+    for(int i = 0; i < BIGREF_CAPACITY; ++i) {
+        for(int j = 1; j < BIGREF_COUNT - i; ++j)
+            tuple_unref(tuples[i]);
+        assert(tuples[i]->refs == 1);
+        tuple_unref(tuples[i]);
+    }
+    free(tuples);
+    return 0;
+}
+
+/**
+ * This test checks that bigrefs works fine after being
+ * created and destroyed BIGREF_DIFF times.
+ */
+static int
+test_bigrefs_2()
+{
+    struct tuple *tuple = create_tuple();
+    for(int i = 0; i < 2; ++i) {
+        assert(tuple->refs == 1);
+        for(int j = 1; j < BIGREF_COUNT; ++j)
+            tuple_ref(tuple);
+        assert(tuple->is_bigref && tuple->ref_index == 0);
+        for(int j = 1; j < BIGREF_COUNT; ++j)
+            tuple_unref(tuple);
+        assert(!tuple->is_bigref && tuple->refs == 1);
+    }
+    tuple_unref(tuple);
+    return 0;
+}
+
+/**
+ * This test checks that indexes are given and free as
+ * intended.
+ */
+static int
+test_bigrefs_3()
+{
+    struct tuple **tuples = (struct tuple **) malloc(BIGREF_CAPACITY *
+                             sizeof(*tuples));
+    for(int i = 0; i < BIGREF_CAPACITY; ++i)
+        tuples[i] = create_tuple();
+    for(int i = 0; i < BIGREF_CAPACITY; ++i) {
+        assert(tuples[i]->refs == 1);
+        for(int j = 1; j < BIGREF_COUNT; ++j)
+            tuple_ref(tuples[i]);
+        assert(tuples[i]->is_bigref);
+    }
+    /** Checks that indexes are given consistently */
+    for(int i = 0; i < BIGREF_CAPACITY; i = i + BIGREF_DIFF) {
+        for(int j = 1; j < BIGREF_COUNT; ++j)
+            tuple_unref(tuples[i]);
+        assert(!tuples[i]->is_bigref);
+    }
+    for(int i = 0; i < BIGREF_CAPACITY; i = i + BIGREF_DIFF) {
+        assert(tuples[i]->refs == 1);
+        for(int j = 1; j < BIGREF_COUNT; ++j)
+            tuple_ref(tuples[i]);
+        assert(tuples[i]->is_bigref && tuples[i]->ref_index == i);
+    }
+
+    /**
+     * Checks that capacity of bigref_list decreased
+     * as intended (for gcov and gdb checks because
+     * capacity cannot be seen outside of tuple.c).
+     */
+    int tmp_indexes[] = {1, 10, 20, 100};
+    for(int i = BIGREF_CAPACITY - 1; i >= 0; --i) {
+        if(i == tmp_indexes[0] || i == tmp_indexes[1] ||
+           i == tmp_indexes[2] || i == tmp_indexes[3])
+            continue;
+        for(int j = 1; j < BIGREF_COUNT; ++j)
+            tuple_unref(tuples[i]);
+        assert(tuples[i]->refs == 1);
+        tuple_unref(tuples[i]);
+    }
+    for(int i = 3; i >= 0; --i) {
+        assert(tuples[tmp_indexes[i]]->ref_index == tmp_indexes[i]);
+        for(int j = 1; j < BIGREF_COUNT; ++j)
+            tuple_unref(tuples[tmp_indexes[i]]);
+        assert(tuples[tmp_indexes[i]]->refs == 1);
+        tuple_unref(tuples[tmp_indexes[i]]);
+    }
+    free(tuples);
+    return 0;
+}
+
+int
+main()
+{
+    header();
+    plan(3);
+
+    memory_init();
+    fiber_init(fiber_c_invoke);
+    tuple_init(NULL);
+
+    tuple_end = mp_encode_array(tuple_end, 1);
+    tuple_end = mp_encode_uint(tuple_end, 2);
+
+    ok(test_bigrefs_1() == 0, "Overall test passed.");
+    ok(test_bigrefs_2() == 0, "Create/destroy test passed.");
+    ok(test_bigrefs_3() == 0, "Non-consistent indexes test passed.");
+
+    tuple_free();
+    fiber_free();
+    memory_free();
+
+    footer();
+    check_plan();
+}
diff --git a/test/unit/tuple_bigref.result b/test/unit/tuple_bigref.result
new file mode 100644
index 0000000..91b9a0f
--- /dev/null
+++ b/test/unit/tuple_bigref.result
@@ -0,0 +1,6 @@
+    *** main ***
+1..3
+ok 1 - Overall test passed.
+ok 2 - Create/destroy test passed.
+ok 3 - Non-consistent indexes test passed.
+    *** main: done ***
-- 
2.7.4