stats: resolve space name from id

`crud.len` supports using space id instead of name. After this patch,
stats wrapper support mapping id to name.

Since using space id is a questionable pattern (see #255), this commit
may be reverted later.

Part of #224

crud/stats/init.lua

@@ -6,6 +6,8 @@ local clock = require('clock')
 local checks = require('checks')
 local fiber = require('fiber')
 local fun = require('fun')
+local log = require('log')
+local vshard = require('vshard')
 
 local dev_checks = require('crud.common.dev_checks')
 local stash = require('crud.common.stash')
@@ -109,6 +111,22 @@ function stats.get(space_name)
     return registry.get(space_name)
 end
 
+local function resolve_space_name(space_id)
+    local replicasets = vshard.router.routeall()
+    if next(replicasets) == nil then
+        log.warn('Failed to resolve space name for stats: no replicasets found')
+        return nil
+    end
+
+    local space = utils.get_space(space_id, replicasets)
+    if space == nil then
+        log.warn('Failed to resolve space name for stats: no space found for id %d', space_id)
+        return nil
+    end
+
+    return space.name
+end
+
 -- Hack to set __gc for a table in Lua 5.1
 -- See https://stackoverflow.com/questions/27426704/lua-5-1-workaround-for-gc-metamethod-for-tables
 -- or https://habr.com/ru/post/346892/
@@ -177,11 +195,24 @@ local function wrap_pairs_gen(build_latency, space_name, op, gen, param, state)
 end
 
 local function wrap_tail(space_name, op, pairs, start_time, call_status, ...)
-    dev_checks('string', 'string', 'boolean', 'number', 'boolean')
+    dev_checks('string|number', 'string', 'boolean', 'number', 'boolean')
 
     local finish_time = clock.monotonic()
     local latency = finish_time - start_time
 
+    -- If space id is provided instead of name, try to resolve name.
+    -- If resolve have failed, use id as string to observe space.
+    -- If using space id will be deprecated, remove this code as well,
+    -- see https://github.com/tarantool/crud/issues/255
+    if type(space_name) ~= 'string' then
+        local name = resolve_space_name(space_name)
+        if name ~= nil then
+            space_name = name
+        else
+            space_name = tostring(space_name)
+        end
+    end
+
     if call_status == false then
         registry.observe(latency, space_name, op, 'error')
         error((...), 2)

test/entrypoint/srv_stats.lua

@@ -23,6 +23,7 @@ package.preload['customers-storage'] = function()
                 },
                 if_not_exists = true,
                 engine = engine,
+                id = 542,
             })
             -- primary index
             customers_space:create_index('id_index', {

test/integration/stats_test.lua

@@ -7,7 +7,9 @@ local stats_registry_utils = require('crud.stats.registry_utils')
 local g = t.group('stats_integration')
 local helpers = require('test.helper')
 
+local space_id = 542
 local space_name = 'customers'
+local non_existing_space_id = 100500
 local non_existing_space_name = 'non_existing_space'
 local new_space_name = 'newspace'
 
@@ -567,6 +569,24 @@ for name, case in pairs(select_cases) do
 end
 
 
+g.test_resolve_name_from_id = function(g)
+    local op = 'len'
+    g.router:call('crud.len', { space_id })
+
+    local stats = g:get_stats(space_name)
+    t.assert_not_equals(stats[op], nil, "Statistics is filled by name")
+end
+
+
+g.test_resolve_nonexisting_space_from_id = function(g)
+    local op = 'len'
+    g.router:call('crud.len', { non_existing_space_id })
+
+    local stats = g:get_stats(tostring(non_existing_space_id))
+    t.assert_not_equals(stats[op], nil, "Statistics is filled by id as string")
+end
+
+
 g.before_test(
     'test_role_reload_do_not_reset_observations',
     generate_stats)