[tarantool-patches] Re: [PATCH 4/4] Introduce storage reload evolution

[Alex Khatskevich]

I have rebased this branch over a new master.

On 01.08.2018 15:36, Vladislav Shpilevoy wrote:
> Thanks for the patch! See 2 comments below.
>
>> diff --git a/test/lua_libs/git_util.lua b/test/lua_libs/git_util.lua
>> new file mode 100644
>> index 0000000..8826c4c
>> --- /dev/null
>> +++ b/test/lua_libs/git_util.lua
>> @@ -0,0 +1,49 @@
>> +--
>> +-- Lua bridge for some of the git commands.
>> +--
>> +local os = require('os')
>> +
>> +--
>> +-- Exec a git command.
>> +-- @param params Table of parameters:
>> +--        * options - git options.
>> +--        * cmd - git command.
>> +--        * args - command arguments.
>> +--        * dir - working directory.
>> +--        * fout - write output to the file.
>> +local function exec_cmd(params)
>
> 1. Lets rename it to just 'exec'. Obviously it executes
> 'cmd'. Also lets make 'cmd' be first mandatory non-named
> parameter and the second is params: args, dir etc.
Fixed.
>
>     local function exec(cmd, params)
>
>> +    local fout = params.fout
>> +    local shell_cmd = {'git'}
>> +    for _, param in pairs({'options', 'cmd', 'args'}) do
>> +        table.insert(shell_cmd, params[param])
>> +    end
>> +    if fout then
>> +        table.insert(shell_cmd, ' >' .. fout)
>> +    end
>> +    shell_cmd = table.concat(shell_cmd, ' ')
>> +    if params.dir then
>> +        shell_cmd = string.format('cd %s && %s', params.dir, shell_cmd)
>> +    end
>> +    local res = os.execute(shell_cmd)
>> +    assert(res == 0, 'Git cmd error: ' .. res)
>> +end
>> +
>> diff --git a/vshard/storage/reload_evolution.lua 
>> b/vshard/storage/reload_evolution.lua
>> new file mode 100644
>> index 0000000..8502a33
>> --- /dev/null
>> +++ b/vshard/storage/reload_evolution.lua
>> @@ -0,0 +1,58 @@
>> +--
>> +-- This module is used to upgrade the vshard.storage on the fly.
>> +-- It updates internal Lua structures in case they are changed
>> +-- in a commit.
>> +--
>> +local log = require('log')
>> +
>> +--
>> +-- Array of upgrade functions.
>> +-- migrations[version] = function which upgrades module version
>> +-- from `version` to `version + 1`.
>> +--
>> +local migrations = {}
>> +
>> +-- Initialize reload_upgrade mechanism
>> +migrations[#migrations + 1] = function (M)
>
> 2. Redundant white space after 'function'.
Fixed.
>
>> +    -- Code to update Lua objects.
>> +end
>> +
>> +--
>> +-- Perform an update based on a version stored in `M` (internals).
>> +-- @param M Old module internals which should be updated.
>> +--
>> +local function upgrade(M)
>> +    local start_version = M.reload_version or 1
>> +    if start_version > #migrations then
>> +        local err_msg = string.format(
>> +            'vshard.storage.reload_evolution: ' ..
>> +            'auto-downgrade is not implemented; ' ..
>> +            'loaded version is %d, upgrade script version is %d',
>> +            start_version, #migrations
>> +        )
>> +        log.error(err_msg)
>> +        error(err_msg)
>> +    end
>> +    for i = start_version, #migrations  do
>> +        local ok, err = pcall(migrations[i], M)
>> +        if ok then
>> +            log.info('vshard.storage.reload_evolution: upgraded to 
>> %d version',
>> +                     i)
>> +        else
>> +            local err_msg = string.format(
>> +                'vshard.storage.reload_evolution: ' ..
>> +                'error during upgrade to %d version: %s', i, err
>> +            )
>> +            log.error(err_msg)
>> +            error(err_msg)
>> +        end
>> +        -- Update the version just after upgrade to have an
>> +        -- actual version in case of an error.
>> +        M.reload_version = i
>> +    end
>> +end
>> +
>> +return {
>> +    version = #migrations,
>> +    upgrade = upgrade,
>> +}
>
Here is a full diff for git_util.lua file

commit 8fbf81cf46b579c158b2b5292a89a0b11ab75494
Author: AKhatskevich <avkhatskevich at tarantool.org>
Date:   Fri Jun 29 20:34:26 2018 +0300

     Introduce storage reload evolution

     Changes:
     1. Introduce storage reload evolution.
     2. Setup cross-version reload testing.

     1:
     This mechanism updates Lua objects on reload in case they are
     changed in a new vshard.storage version.

     Since this commit, any change in vshard.storage.M has to be
     reflected in vshard.storage.reload_evolution to guarantee
     correct reload.

     2:
     The testing uses git infrastructure and is performed in the following
     way:
     1. Copy old version of vshard to a temp folder.
     2. Run vshard on this code.
     3. Checkout the latest version of the vshard sources.
     4. Reload vshard storage.
     5. Make sure it works (Perform simple tests).

     Notes:
     * this patch contains some legacy-driven decisions:
       1. SOURCEDIR path retrieved differently in case of
          packpack build.
       2. git directory in the `reload_evolution/storage` test
          is copied with respect to Centos 7 and `ro` mode of
          SOURCEDIR.

     Closes #112 #125

diff --git a/test/lua_libs/git_util.lua b/test/lua_libs/git_util.lua
new file mode 100644
index 0000000..48f9827
--- /dev/null
+++ b/test/lua_libs/git_util.lua
@@ -0,0 +1,46 @@
+--
+-- Lua bridge for some of the git commands.
+--
+local os = require('os')
+
+--
+-- Exec a git command.
+-- @param cmd Git command to run.
+-- @param params Table of parameters:
+--        * options - git options.
+--        * args - command arguments.
+--        * dir - working directory.
+--        * fout - write output to the file.
+local function exec(cmd, params)
+    params.options = params.options or ''
+    params.args = params.args or ''
+    local shell_cmd = string.format('git %s %s %s', params.options, cmd,
+                                    params.args)
+    if params.fout then
+        shell_cmd = string.format('%s >%s', shell_cmd, params.fout)
+    end
+    if params.dir then
+        shell_cmd = string.format('cd %s && %s', params.dir, shell_cmd)
+    end
+    local res = os.execute(shell_cmd)
+    assert(res == 0, 'Git cmd error: ' .. res)
+end
+
+local function log_hashes(params)
+    params.args = "--format='%h' " .. params.args
+    -- Store log to the file.
+    local temp_file = os.tmpname()
+    params.fout = temp_file
+    exec('log', params)
+    local lines = {}
+    for line in io.lines(temp_file) do
+        table.insert(lines, line)
+    end
+    os.remove(temp_file)
+    return lines
+end
+
+return {
+    exec = exec,
+    log_hashes = log_hashes
+}