From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp58.i.mail.ru (smtp58.i.mail.ru [217.69.128.38]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dev.tarantool.org (Postfix) with ESMTPS id A51C346970E for ; Wed, 5 Feb 2020 01:53:50 +0300 (MSK) From: Vladislav Shpilevoy Date: Tue, 4 Feb 2020 23:53:44 +0100 Message-Id: <1a28ebaa58b81f4cbc3a1656cf364f281919ade9.1580856721.git.v.shpilevoy@tarantool.org> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [Tarantool-patches] [PATCH v2 1/4] tuple: don't truncate float in :update() List-Id: Tarantool development patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: tarantool-patches@dev.tarantool.org, kostja.osipov@gmail.com, imun@tarantool.org, korablev@tarantool.org Before the patch there were the rules: * float +/- double = double * double +/- double = double * float +/- float = float The rules were applied regardless of values. That led to a problem when float + float exceeding maximal float value could fit into double, but was stored as an infinity. The patch makes so that if a floating point arithmetic operation result fits into float, it is stored as float. Otherwise as double. Regardless of initial types. This alongside saves some memory for cases when doubles can be stored as floats, and therefore takes 4 less bytes. Although these cases are rare, because any not integer value stored in a double may have a long garbage tail in its fraction. Closes #4701 --- src/box/xrow_update_field.c | 10 ++++-- test/box/update.result | 65 +++++++++++++++++++++++++++++++++++++ test/box/update.test.lua | 45 +++++++++++++++++++++++++ 3 files changed, 117 insertions(+), 3 deletions(-) diff --git a/src/box/xrow_update_field.c b/src/box/xrow_update_field.c index 7c0f5fb5e..6ac29de5d 100644 --- a/src/box/xrow_update_field.c +++ b/src/box/xrow_update_field.c @@ -32,6 +32,8 @@ #include "tuple_format.h" #include "mp_extension_types.h" +#include + /* {{{ Error helpers. */ /** Take a string identifier of a field being updated by @a op. */ @@ -400,13 +402,15 @@ xrow_update_arith_make(struct xrow_update_op *op, unreachable(); break; } - if (lowest_type == XUPDATE_TYPE_DOUBLE) { + float fc = (float) c; + if ((lowest_type == XUPDATE_TYPE_DOUBLE && c != (double) fc) || + (lowest_type == XUPDATE_TYPE_FLOAT && + (c >= FLT_MAX || c <= -FLT_MAX))) { ret->type = XUPDATE_TYPE_DOUBLE; ret->dbl = c; } else { - assert(lowest_type == XUPDATE_TYPE_FLOAT); ret->type = XUPDATE_TYPE_FLOAT; - ret->flt = (float)c; + ret->flt = fc; } } else { decimal_t a, b, c; diff --git a/test/box/update.result b/test/box/update.result index 28ba47831..dfbd8714f 100644 --- a/test/box/update.result +++ b/test/box/update.result @@ -1647,3 +1647,68 @@ t:update({{'=', '[2].d.g', 6000}, {'#', '[2].d.old.old', 1}}) s:drop() --- ... +-- +-- gh-4701: arith operations should not truncate result when +-- float + float fits double. +-- +msgpackffi = require('msgpackffi') +--- +... +mp_array_1 = 0x91 +--- +... +mp_double = 0xcb +--- +... +mp_float = 0xca +--- +... +flt_max = 3.402823466e+38 +--- +... +uint_max = 18446744073709551615ULL +--- +... +-- Double + double is float if result fits. \ +-- Double + double is double if result does not fit float. \ +-- Double + float is float if result fits. \ +-- Double + float is double if result does not fit float. \ +-- Float + float is float when no overflow. \ +-- Float + float is double when overflow. \ +-- Float + int is float when fits the float range. \ +-- Precision matters too. Double is used when need to avoid \ +-- precision loss. \ +tests = { \ + {{'double', 1}, {'double', 1}, mp_float}, \ + {{'double', flt_max}, {'double', flt_max}, mp_double}, \ + {{'double', 1}, {'float', 1}, mp_float}, \ + {{'double', flt_max}, {'float', flt_max}, mp_double}, \ + {{'float', 1}, {'float', 1}, mp_float}, \ + {{'float', flt_max}, {'float', flt_max}, mp_double}, \ + {{'float', -flt_max}, {'float', -flt_max}, mp_double}, \ + {{'float', 1}, {'int', 1}, mp_float}, \ + {{'float', flt_max}, {'uint64_t', uint_max}, mp_double}, \ + {{'float', 1.0001}, {'double', 1.0000000000001}, mp_double}, \ +} +--- +... +err = nil +--- +... +for i, test in pairs(tests) do \ + local val1 = ffi.cast(test[1][1], test[1][2]) \ + local val2 = ffi.cast(test[2][1], test[2][2]) \ + local t = box.tuple.new({val1}) \ + t = t:update({{'+', 1, val2}}) \ + local m = msgpackffi.encode(t) \ + if m:byte(1) ~= mp_array_1 or m:byte(2) ~= test[3] then \ + err = {i, test, t, m:byte(1), m:byte(2)} \ + break \ + end \ +end +--- +... +err +--- +- null +... diff --git a/test/box/update.test.lua b/test/box/update.test.lua index 314ebef05..74f9c62e2 100644 --- a/test/box/update.test.lua +++ b/test/box/update.test.lua @@ -597,3 +597,48 @@ t:update({{'=', '[2].d.g', 6000}, {'=', '[2].d.new.new', -1}}) t:update({{'=', '[2].d.g', 6000}, {'#', '[2].d.old.old', 1}}) s:drop() + +-- +-- gh-4701: arith operations should not truncate result when +-- float + float fits double. +-- +msgpackffi = require('msgpackffi') +mp_array_1 = 0x91 +mp_double = 0xcb +mp_float = 0xca +flt_max = 3.402823466e+38 +uint_max = 18446744073709551615ULL +tests = { \ +-- Double + double is float if result fits. \ + {{'double', 1}, {'double', 1}, mp_float}, \ +-- Double + double is double if result does not fit float. \ + {{'double', flt_max}, {'double', flt_max}, mp_double}, \ +-- Double + float is float if result fits. \ + {{'double', 1}, {'float', 1}, mp_float}, \ +-- Double + float is double if result does not fit float. \ + {{'double', flt_max}, {'float', flt_max}, mp_double}, \ +-- Float + float is float when no overflow. \ + {{'float', 1}, {'float', 1}, mp_float}, \ +-- Float + float is double when overflow. \ + {{'float', flt_max}, {'float', flt_max}, mp_double}, \ + {{'float', -flt_max}, {'float', -flt_max}, mp_double}, \ +-- Float + int is float when fits the float range. \ + {{'float', 1}, {'int', 1}, mp_float}, \ + {{'float', flt_max}, {'uint64_t', uint_max}, mp_double}, \ +-- Precision matters too. Double is used when need to avoid \ +-- precision loss. \ + {{'float', 1.0001}, {'double', 1.0000000000001}, mp_double}, \ +} +err = nil +for i, test in pairs(tests) do \ + local val1 = ffi.cast(test[1][1], test[1][2]) \ + local val2 = ffi.cast(test[2][1], test[2][2]) \ + local t = box.tuple.new({val1}) \ + t = t:update({{'+', 1, val2}}) \ + local m = msgpackffi.encode(t) \ + if m:byte(1) ~= mp_array_1 or m:byte(2) ~= test[3] then \ + err = {i, test, t, m:byte(1), m:byte(2)} \ + break \ + end \ +end +err -- 2.21.1 (Apple Git-122.3)