[PATCH v2] box: allow vinyl_memory set to 0 in config

[Serge Petrenko <sergepetrenko@tarantool.org>]

Sorry, forgot to post diff.

In 1.9 it was possible to have a vinylless configuration with
vinyl_memory=0, allow to do this in 1.10 by adjusting sanity
checks for vinyl_memory and memtx_memory. Now banning only
negative values.
memtx_memory check was changed for consistency, trying to
set memtx_memory to 0 fails anyways.
Also added a test to check that vinyl_memory can actually
be set to 0.

Closes: #3468
---
https://github.com/tarantool/tarantool/tree/sergepetrenko/gh-3468-allow-0-vinyl-memory
https://github.com/tarantool/tarantool/issues/3468

Changes in v2:
- added a test case to check vinyl_memory=0 is legal.


 src/box/box.cc            | 8 ++++----
 test/box-tap/cfg.test.lua | 8 +++++++-
 test/box/cfg.result       | 4 ++--
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/src/box/box.cc b/src/box/box.cc
index dcbf52e10..7d6dfc8f6 100644
--- a/src/box/box.cc
+++ b/src/box/box.cc
@@ -495,9 +495,9 @@ box_check_wal_max_size(int64_t wal_max_size)
 static int64_t
 box_check_memtx_memory(int64_t memory)
 {
-	if (memory <= 0) {
+	if (memory < 0) {
 		tnt_raise(ClientError, ER_CFG, "memtx_memory",
-			  "must be greater than 0");
+			  "must not be less than 0");
 	}
 	return memory;
 }
@@ -505,9 +505,9 @@ box_check_memtx_memory(int64_t memory)
 static int64_t
 box_check_vinyl_memory(int64_t memory)
 {
-	if (memory <= 0) {
+	if (memory < 0) {
 		tnt_raise(ClientError, ER_CFG, "vinyl_memory",
-			  "must be greater than 0");
+			  "must not be less than 0");
 	}
 	return memory;
 }
diff --git a/test/box-tap/cfg.test.lua b/test/box-tap/cfg.test.lua
index b93a21f35..764fade93 100755
--- a/test/box-tap/cfg.test.lua
+++ b/test/box-tap/cfg.test.lua
@@ -6,7 +6,7 @@ local socket = require('socket')
 local fio = require('fio')
 local uuid = require('uuid')
 local msgpack = require('msgpack')
-test:plan(91)
+test:plan(93)
 
 --------------------------------------------------------------------------------
 -- Invalid values
@@ -82,9 +82,15 @@ os.execute("rm -rf vinyl")
 box.cfg{
     log="tarantool.log",
     memtx_memory=104857600,
+    vinyl_memory=0,
     wal_mode = "", -- "" means default value
 }
 
+status, result = pcall(testfun)
+test:ok(status  and result == "table", "allow vinyl_memory set to 0 in box.cfg")
+test:is(box.cfg.vinyl_memory, 0, "vinyl_memory actually set to 0")
+
+box.cfg{vinyl_memory=128 * 1024 * 1024}
 -- gh-678: vinyl engine creates vinyl dir with empty 'snapshot' file
 test:isnil(io.open("vinyl", 'r'), 'vinyl_dir is not auto-created')
 
diff --git a/test/box/cfg.result b/test/box/cfg.result
index 7604f61dc..6debb564b 100644
--- a/test/box/cfg.result
+++ b/test/box/cfg.result
@@ -240,11 +240,11 @@ box.cfg{memtx_memory = "100500"}
 ...
 box.cfg{memtx_memory = -1}
 ---
-- error: 'Incorrect value for option ''memtx_memory'': must be greater than 0'
+- error: 'Incorrect value for option ''memtx_memory'': must not be less than 0'
 ...
 box.cfg{vinyl_memory = -1}
 ---
-- error: 'Incorrect value for option ''vinyl_memory'': must be greater than 0'
+- error: 'Incorrect value for option ''vinyl_memory'': must not be less than 0'
 ...
 box.cfg{vinyl = "vinyl"}
 ---
-- 
2.15.2 (Apple Git-101.1)