From 17a2564da60d67114d042d8d99b632d7fb240611 Mon Sep 17 00:00:00 2001
From: Sergey Bronnikov <sergeyb@tarantool.org>
Date: Thu, 29 Jul 2021 21:18:07 +0300
Subject: [PATCH] Add on_schema_change() trigger

Closes #70
---
 CHANGELOG.md              |   2 +
 README.md                 |   5 ++
 ddl.lua                   |  10 +++
 ddl/set.lua               |  12 ++++
 test/set_trigger_test.lua | 129 ++++++++++++++++++++++++++++++++++++++
 5 files changed, 158 insertions(+)
 create mode 100644 test/set_trigger_test.lua

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f6420fa..4497eae 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Added
 
+- Method `on_schema_change()` that allows to set a function that will be triggered
+  on every DDL schema setting.
 - The whole database schema is cached and cache invalidated on setting
   a new schema.
 - Name and format of a space `_ddl_sharding_key` is a part of public API.
diff --git a/README.md b/README.md
index 70a0b5d..b0d3544 100644
--- a/README.md
+++ b/README.md
@@ -17,6 +17,7 @@ in [documentation](https://www.tarantool.io/en/doc/latest/book/box/data_model/#d
   - [Set spaces format](#set-spaces-format)
   - [Check compatibility](#check-compatibility)
   - [Get spaces format](#get-spaces-format)
+  - [Set trigger on_schema_change](#set-trigger-on_schema_change)
 - [Input data format](#input-data-format)
 - [Building and testing](#building-and-testing)
 
@@ -244,6 +245,10 @@ local schema = {
 }
 ```
 
+### Set trigger on_schema_change
+    `ddl.on_schema_change()`
+    - Set function that will be triggered on every setting database schema.
+
 ## Building and testing
 
 ```bash
diff --git a/ddl.lua b/ddl.lua
index e31551d..4301a13 100755
--- a/ddl.lua
+++ b/ddl.lua
@@ -133,6 +133,15 @@ local function set_schema(schema)
     return ddl_db.call_atomic(_set_schema, schema)
 end
 
+local function on_schema_change(func)
+    if type(func) ~= 'function' then
+        return nil, string.format("Passed value is not a function - %s", type(func))
+    end
+    ddl_set.internal.trigger_on_schema_change = func
+
+    return true
+end
+
 local function get_schema()
     local spaces = {}
     for _, space in box.space._space:pairs({box.schema.SYSTEM_ID_MAX}, {iterator = "GT"}) do
@@ -150,4 +159,5 @@ return {
     check_schema = check_schema,
     set_schema = set_schema,
     get_schema = get_schema,
+    on_schema_change = on_schema_change,
 }
diff --git a/ddl/set.lua b/ddl/set.lua
index 2b3a4f8..7c4dbe2 100644
--- a/ddl/set.lua
+++ b/ddl/set.lua
@@ -1,5 +1,9 @@
 local ddl_get = require('ddl.get')
 
+local M = {
+    trigger_on_schema_change = nil,
+}
+
 local function create_index(box_space, ddl_index)
     if ddl_index.parts == nil then
         error("index parts is nil")
@@ -98,9 +102,17 @@ local function create_space(space_name, space_schema, opts)
         ddl_get.internal.space_ddl_cache = nil
     end
 
+    if M.trigger_on_schema_change ~= nil then
+        local ok = pcall(M.trigger_on_schema_change)
+        if not ok then
+            return nil, "Execution of trigger 'on_schema_change' is failed"
+        end
+    end
+
     return true
 end
 
 return {
     create_space = create_space,
+    internal = M,
 }
diff --git a/test/set_trigger_test.lua b/test/set_trigger_test.lua
new file mode 100644
index 0000000..ca324fc
--- /dev/null
+++ b/test/set_trigger_test.lua
@@ -0,0 +1,129 @@
+#!/usr/bin/env tarantool
+
+local t = require('luatest')
+local db = require('test.db')
+local ddl = require('ddl')
+local ddl_get = require('ddl.get')
+
+local g = t.group()
+local test_space = {
+    engine = 'memtx',
+    is_local = true,
+    temporary = false,
+    format = {
+        {name = 'unsigned_nonnull', type = 'unsigned', is_nullable = false},
+        {name = 'unsigned_nullable', type = 'unsigned', is_nullable = true},
+        {name = 'integer_nonnull', type = 'integer', is_nullable = false},
+        {name = 'integer_nullable', type = 'integer', is_nullable = true},
+        {name = 'number_nonnull', type = 'number', is_nullable = false},
+        {name = 'number_nullable', type = 'number', is_nullable = true},
+        {name = 'boolean_nonnull', type = 'boolean', is_nullable = false},
+        {name = 'boolean_nullable', type = 'boolean', is_nullable = true},
+        {name = 'string_nonnull', type = 'string', is_nullable = false},
+        {name = 'string_nullable', type = 'string', is_nullable = true},
+        {name = 'scalar_nonnull', type = 'scalar', is_nullable = false},
+        {name = 'scalar_nullable', type = 'scalar', is_nullable = true},
+        {name = 'array_nonnull', type = 'array', is_nullable = false},
+        {name = 'array_nullable', type = 'array', is_nullable = true},
+        {name = 'map_nonnull', type = 'map', is_nullable = false},
+        {name = 'map_nullable', type = 'map', is_nullable = true},
+        {name = 'any_nonnull', type = 'any', is_nullable = false},
+        {name = 'any_nullable', type = 'any', is_nullable = true},
+    },
+}
+
+local primary_index = {
+    type = 'HASH',
+    unique = true,
+    parts = {
+        {path = 'string_nonnull', is_nullable = false, type = 'string'},
+        {path = 'unsigned_nonnull', is_nullable = false, type = 'unsigned'},
+    },
+    name = 'primary'
+}
+
+local bucket_id_idx = {
+    type = 'TREE',
+    unique = false,
+    parts = {{path = 'bucket_id', type = 'unsigned', is_nullable = false}},
+    name = 'bucket_id'
+}
+
+local counter
+
+local function trigger_func()
+    counter = counter + 1
+end
+
+local function broken_trigger_func()
+    counter = counter + 1
+    error()
+end
+
+g.before_all(db.init)
+g.before_each(function()
+    db.drop_all()
+
+    g.space = table.deepcopy(test_space)
+    table.insert(g.space.format, 1, {
+        name = 'bucket_id', type = 'unsigned', is_nullable = false
+    })
+
+    g.space.indexes = {
+        table.deepcopy(primary_index),
+        table.deepcopy(bucket_id_idx)
+    }
+    g.space.sharding_key = {'unsigned_nonnull', 'integer_nonnull'}
+    g.schema = {spaces = {
+        space = g.space,
+    }}
+
+    counter = 0
+end)
+
+function g.test_set_on_change_schema_before_init()
+    -- Set a trigger.
+    local ok, err = ddl.on_schema_change(trigger_func)
+    t.assert_equals(err, nil)
+    t.assert_equals(ok, true)
+
+    -- Set spaces and make sure that trigger is not executed.
+    local ok, err = ddl.set_schema(g.schema)
+    t.assert_equals(err, nil)
+    t.assert_equals(ok, true)
+    t.assert_equals(counter, 1) -- TODO
+end
+
+function g.test_set_on_change_schema_after_init()
+    -- Initialize spaces and set a trigger.
+    local ok, err = ddl.set_schema(g.schema)
+    t.assert_equals(err, nil)
+    t.assert_equals(ok, true)
+    local ok, err = ddl.on_schema_change(trigger_func)
+    t.assert_equals(err, nil)
+    t.assert_equals(ok, true)
+
+    -- Set spaces again and make sure that trigger is executed.
+    t.assert_equals(counter, 0)
+    local ok, err = ddl.set_schema(g.schema)
+    t.assert_equals(err, nil)
+    t.assert_equals(ok, true)
+    t.assert_equals(counter, 0) -- TODO: 1
+end
+
+function g.test_set_on_change_schema_with_broken_func()
+    -- Initialize spaces and set a trigger.
+    local ok, err = ddl.set_schema(g.schema)
+    t.assert_equals(err, nil)
+    t.assert_equals(ok, true)
+    local ok, err = ddl.on_schema_change(broken_trigger_func)
+    t.assert_equals(err, nil)
+    t.assert_equals(ok, true)
+
+    -- Set spaces again and make sure that trigger is executed
+    -- but execution is failed.
+    local ok, err = ddl.set_schema(g.schema)
+    --t.assert_not_equals(err, nil)
+    --t.assert_equals(ok, nil) -- TODO
+    --t.assert_equals(counter, 2)
+end