Log potentially long count calls

Potentially long count calls on user spaces tend to be dangerous.

A critical log entry containing the current stack traceback is created
upon potentially long count calls — a user can explicitly request a
full scan though by passing fullscan = true to count's options table
argument in which a case a log entry will not be created.

Closes #276

Author: oleg-jukovec

CHANGELOG.md

@@ -10,10 +10,11 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Added
 
 ### Changed
-* Behaviour of potentially long `select` calls: a critical log entry containing
-  the current stack traceback is created upon such function calls — an user can
-  explicitly request a full scan through by passing `fullscan=true` to `select`
-  options table argument in which a case a log entry will not be created (#276).
+* Behaviour of potentially long `select` and `count` calls: a critical log entry
+  containing the current stack traceback is created upon such function calls —
+  an user can explicitly request a full scan through by passing `fullscan=true`
+  to `select` or `count` options table argument in which a case a log entry will
+  not be created (#276).
 
 ### Fixed
 

README.md

@@ -690,6 +690,8 @@ where:
   * `force_map_call` (`?boolean`) - if `true`
     then the map call is performed without any optimizations even,
     default value is `false`
+  * `fullscan` (`?boolean`) - if `true` then a critical log entry will be skipped
+    on potentially long `count`, see [avoiding full scan](doc/select.md#avoiding-full-scan).
   * `mode` (`?string`, `read` or `write`) - if `write` is specified then `count` is
     performed on master, default value is `read`
   * `prefer_replica` (`?boolean`) - if `true` then the preferred target is one of
@@ -699,9 +701,9 @@ where:
     default value is `false`
 
 ```lua
-crud.count('customers', {{'<=', 'age', 35}})
+crud.count('customers', {{'==', 'age', 35}})
 ---
-- 5
+- 1
 ...
 ```
 

crud/count.lua

@@ -10,6 +10,7 @@ local sharding = require('crud.common.sharding')
 local filters = require('crud.compare.filters')
 local count_plan = require('crud.compare.plan')
 local dev_checks = require('crud.common.dev_checks')
+local ratelimit = require('crud.ratelimit')
 local schema = require('crud.common.schema')
 local sharding_metadata_module = require('crud.common.sharding.sharding_metadata')
 
@@ -90,6 +91,22 @@ function count.init()
     _G._crud.count_on_storage = count_on_storage
 end
 
+local check_count_safety_rl = ratelimit.new()
+local function check_count_safety(space_name, plan, opts)
+    if opts.fullscan == true then
+        return
+    end
+
+    local iter = plan.tarantool_iter
+    if iter == box.index.EQ or iter == box.index.REQ then
+        return
+    end
+
+    local rl = check_count_safety_rl
+    local traceback = debug.traceback()
+    rl:log_crit("Potentially long count from space '%s'\n %s", space_name, traceback)
+end
+
 -- returns result, err, need_reload
 -- need_reload indicates if reloading schema could help
 -- see crud.common.schema.wrap_func_reload()
@@ -98,6 +115,7 @@ local function call_count_on_router(space_name, user_conditions, opts)
         timeout = '?number',
         bucket_id = '?number|cdata',
         force_map_call = '?boolean',
+        fullscan = '?boolean',
         yield_every = '?number',
         prefer_replica = '?boolean',
         balance = '?boolean',
@@ -147,6 +165,7 @@ local function call_count_on_router(space_name, user_conditions, opts)
     if err ~= nil then
         return nil, CountError:new("Failed to plan count: %s", err), const.NEED_SCHEMA_RELOAD
     end
+    check_count_safety(space_name, plan, opts)
 
     -- set replicasets to count from
     local replicasets_to_count = replicasets
@@ -297,6 +316,7 @@ function count.call(space_name, user_conditions, opts)
         timeout = '?number',
         bucket_id = '?number|cdata',
         force_map_call = '?boolean',
+        fullscan = '?boolean',
         yield_every = '?number',
         prefer_replica = '?boolean',
         balance = '?boolean',

test/helper.lua

@@ -509,4 +509,17 @@ function helpers.assert_timeout_error(value, message)
     error(err, 2)
 end
 
+function helpers.fflush_main_server_stdout(cluster, capture)
+    -- Sometimes we have a delay here. This hack helps to wait for the end of
+    -- the output. It shouldn't take much time.
+    cluster.main_server.net_box:eval([[
+        require('log').error("crud fflush stdout message")
+    ]])
+    local captured = ""
+    while not string.find(captured, "crud fflush stdout message", 1, true) do
+        captured = captured .. (capture:flush().stdout or "")
+    end
+    return captured
+end
+
 return helpers

test/integration/count_test.lua

@@ -2,6 +2,7 @@ local fio = require('fio')
 local clock = require('clock')
 
 local t = require('luatest')
+local luatest_capture = require('luatest.capture')
 
 local helpers = require('test.helper')
 
@@ -26,6 +27,9 @@ pgroup.before_all(function(g)
     g.cluster:server('router').net_box:eval([[
         require('crud').cfg{ stats = true }
     ]])
+    g.cluster:server('router').net_box:eval([[
+        require('crud.ratelimit').disable()
+    ]])
 end)
 
 pgroup.after_all(function(g) helpers.stop_cluster(g.cluster) end)
@@ -37,14 +41,14 @@ pgroup.before_each(function(g)
 end)
 
 pgroup.test_count_non_existent_space = function(g)
-    local result, err = g.cluster.main_server.net_box:call('crud.count', {'non_existent_space'})
+    local result, err = g.cluster.main_server.net_box:call('crud.count', {'non_existent_space', nil, {fullscan = true}})
 
     t.assert_equals(result, nil)
     t.assert_str_contains(err.err, "Space \"non_existent_space\" doesn't exist")
 end
 
 pgroup.test_count_empty_space = function(g)
-    local result, err = g.cluster.main_server.net_box:call('crud.count', {'customers'})
+    local result, err = g.cluster.main_server.net_box:call('crud.count', {'customers', nil, {fullscan = true}})
 
     t.assert_equals(err, nil)
     t.assert_equals(result, 0)
@@ -69,7 +73,7 @@ pgroup.test_not_valid_operation = function(g)
     }
 
     local result, err = g.cluster.main_server.net_box:call('crud.count',
-            {'customers', conditions}
+            {'customers', conditions, {fullscan = true}}
     )
 
     t.assert_equals(result, nil)
@@ -89,6 +93,79 @@ pgroup.test_conditions_with_non_existed_field = function(g)
     t.assert_equals(result, 0)
 end
 
+
+local count_safety_cases = {
+    nil_and_nil_opts = {
+        has_crit = true,
+        user_conditions = nil,
+        opts = nil,
+    },
+    fullscan_false = {
+        has_crit = true,
+        user_conditions = nil,
+        opts = {fullscan = false},
+    },
+    fullscan_true = {
+        has_crit = false,
+        user_conditions = nil,
+        opts = {fullscan = true},
+    },
+    non_equal_conditions = {
+        has_crit = true,
+        user_conditions = {
+            {'>=', 'last_name', 'A'},
+            {'<=', 'last_name', 'Z'},
+            {'>', 'age', 20},
+            {'<', 'age', 30},
+        },
+        opts = nil,
+    },
+    equal_condition = {
+        has_crit = false,
+        user_conditions = {
+            {'>=', 'last_name', 'A'},
+            {'<=', 'last_name', 'Z'},
+            {'=', 'age', 25},
+        },
+        opts = nil,
+    },
+    equal_condition2 = {
+        has_crit = false,
+        user_conditions = {
+            {'>=', 'last_name', 'A'},
+            {'<=', 'last_name', 'Z'},
+            {'==', 'age', 25},
+        },
+        opts = nil,
+    },
+}
+
+for name, case in pairs(count_safety_cases) do
+    local space = 'customers'
+    local crit_log = "C> Potentially long count from space '" .. space .. "'"
+    local test_name = ('test_count_safety_%s'):format(name)
+
+    pgroup[test_name] = function(g)
+        local uc = case.user_conditions
+        local opts = case.opts
+        local capture = luatest_capture:new()
+        capture:enable()
+
+        local _, err = g.cluster.main_server.net_box:call('crud.count', {space, uc, opts})
+        t.assert_equals(err, nil)
+
+        local captured = helpers.fflush_main_server_stdout(g.cluster, capture)
+
+        if case.has_crit then
+            t.assert_str_contains(captured, crit_log)
+        else
+            t.assert_equals(string.find(captured, crit_log, 1, true), nil)
+        end
+
+        capture:disable()
+    end
+end
+
 pgroup.test_count_all = function(g)
     -- let's insert five tuples on different replicasets
     -- (two tuples on one replica and three on the other)
@@ -118,7 +195,7 @@ pgroup.test_count_all = function(g)
     })
 
     local result, err = g.cluster.main_server.net_box:call('crud.count',
-            {'customers'}
+            {'customers', nil, {fullscan = true}}
     )
 
     t.assert_equals(err, nil)
@@ -154,7 +231,7 @@ pgroup.test_count_all_with_yield_every = function(g)
     })
 
     local result, err = g.cluster.main_server.net_box:call('crud.count',
-            {'customers', nil, {yield_every = 1}}
+            {'customers', nil, {yield_every = 1, fullscan = true}}
     )
 
     t.assert_equals(err, nil)
@@ -190,7 +267,7 @@ pgroup.test_count_all_with_yield_every_0 = function(g)
     })
 
     local result, err = g.cluster.main_server.net_box:call('crud.count',
-            {'customers', nil, {yield_every = 0}}
+            {'customers', nil, {yield_every = 0, fullscan = true}}
     )
 
     t.assert_equals(result, nil)
@@ -312,7 +389,7 @@ pgroup.test_ge_condition_with_index = function(g)
     local expected_len = 3
 
     local result, err = g.cluster.main_server.net_box:call('crud.count',
-            {'customers', conditions}
+            {'customers', conditions, {fullscan = true}}
     )
 
     t.assert_equals(err, nil)
@@ -354,7 +431,7 @@ pgroup.test_gt_condition_with_index = function(g)
     local expected_len = 1
 
     local result, err = g.cluster.main_server.net_box:call('crud.count',
-            {'customers', conditions}
+            {'customers', conditions, {fullscan = true}}
     )
 
     t.assert_equals(err, nil)
@@ -396,7 +473,7 @@ pgroup.test_le_condition_with_index = function(g)
     local expected_len = 4
 
     local result, err = g.cluster.main_server.net_box:call('crud.count',
-            {'customers', conditions}
+            {'customers', conditions, {fullscan = true}}
     )
 
     t.assert_equals(err, nil)
@@ -438,7 +515,7 @@ pgroup.test_lt_condition_with_index = function(g)
     local expected_len = 2
 
     local result, err = g.cluster.main_server.net_box:call('crud.count',
-            {'customers', conditions}
+            {'customers', conditions, {fullscan = true}}
     )
 
     t.assert_equals(err, nil)
@@ -543,6 +620,7 @@ pgroup.test_opts_not_damaged = function(g)
         mode = 'read',
         prefer_replica = false,
         balance = false,
+        fullscan = true
     }
     local new_count_opts, err = g.cluster.main_server:eval([[
          local crud = require('crud')
@@ -586,7 +664,7 @@ pgroup.test_count_no_map_reduce = function(g)
     local result, err = g.cluster.main_server.net_box:call('crud.count', {
         'customers',
         nil,
-        {bucket_id = 2804, timeout = 1},
+        {bucket_id = 2804, timeout = 1, fullscan = true},
     })
     t.assert_equals(err, nil)
     t.assert_equals(result, 1)
@@ -647,7 +725,7 @@ pgroup.test_count_timeout = function(g)
     local begin = clock.proc()
 
     local result, err = g.cluster.main_server.net_box:call('crud.count',
-            {'customers', conditions, {timeout = timeout}}
+            {'customers', conditions, {timeout = timeout, fullscan = true}}
     )
 
     t.assert_equals(err, nil)
@@ -688,7 +766,7 @@ pgroup.test_composite_index = function(g)
     }
 
     -- no after
-    local result, err = g.cluster.main_server.net_box:call('crud.count', {'customers', conditions})
+    local result, err = g.cluster.main_server.net_box:call('crud.count', {'customers', conditions}, {fullscan = true})
 
     t.assert_equals(err, nil)
     t.assert_equals(result, 4)

test/integration/read_calls_strategies_test.lua

@@ -111,7 +111,8 @@ pgroup.test_count = function(g)
     local _, err = g.cluster.main_server.net_box:call('crud.count', {'customers', nil, {
         mode = g.params.mode,
         balance = g.params.balance,
-        prefer_replica = g.params.prefer_replica
+        prefer_replica = g.params.prefer_replica,
+        fullscan = true
     }})
     t.assert_equals(err, nil)
     local vshard_calls = g.get_vshard_calls('call_impl')

test/integration/select_test.lua

@@ -174,15 +174,7 @@ for name, case in pairs(select_safety_cases) do
         local _, err = g.cluster.main_server.net_box:call('crud.select', {space, uc, opts})
         t.assert_equals(err, nil)
 
-        -- We have a delay here. This hack helps to wait for the end of the output.
-        -- It shouldn't take much time.
-        g.cluster:server('router').net_box:eval([[
-            require('log').error("end of test_select_nil case")
-        ]])
-        local captured = ""
-        while not string.find(captured, "end of test_select_nil case", 1, true) do
-            captured = captured .. (capture:flush().stdout or "")
-        end
+        local captured = helpers.fflush_main_server_stdout(g.cluster, capture)
 
         if case.has_crit then
             t.assert_str_contains(captured, crit_log)