Module cartridge.twophase

twophase_commit (opts)

Execute the two-phase commit algorithm.

• (upload) If opts.upload_data isn’t nil , spread it across the servers from opts.uri_list .
• (prepare) Run the opts.fn_prepare function.
• (commit) If all the servers do return true , call opts.fn_commit on every server.
• (abort) Otherwise, if at least one server does return nil, err or throws an exception, call opts.fn_abort on servers which were prepared successfully.

Parameters:

• opts:
  • uri_list: ({string,…}) array of URIs for performing twophase commit
  • upload_data: any Lua object to be uploaded
  • activity_name: (optional string) understandable name of activity used for logging(default: “twophase_commit”)
  • fn_prepare: (string)
  • fn_commit: (string)
  • fn_abort: (string)

Returns:

(boolean) true

Or

(nil)

(table) Error description

Usage:

local my_2pc_data = nil

function _G.my_2pc_prepare(upload_id)
    local data = upload.inbox[upload_id]
    upload.inbox[upload_id] = nil
    if my_2pc_data ~= nil then
        error('Two-phase commit is locked')
    end
    my_2pc_data = data
end

function _G.my_2pc_commit()
    -- Apply my_2pc_data
    ...
end

function _G.my_2pc_abort()
    twophase_data = nil
end

require('cartridge.twophase').twophase_commit({
    uri_list = {...},
    upload_data = ...,
    activity_name = 'my_2pc',
    fn_prepare = '_G.my_2pc_prepare',
    fn_commit = '_G.my_2pc_commit',
    fn_abort = '_G.my_2pc_abort',
})

patch_clusterwide (patch)

Edit the clusterwide configuration. Top-level keys are merged with the current configuration. To remove a top-level section, use patch_clusterwide{key = box.NULL} .

The function executes following steps:

1. Patches the current configuration.
2. Validates topology on the current server.

III. Executes two-phase commit on all servers in the cluster excluding expelled and disabled ones.

Parameters:

• patch: (table)

Returns:

(boolean) true

Or

(nil)

(table) Error description

force_reapply (uuids)

Forcefully apply config to the given instances.

In particular:

• Abort two-phase commit (remove config.prepare lock)
• Upload the active config from the current instance.
• Apply it (reconfigure all roles)

(Added in v2.3.0-68)

Parameters:

• uuids: ({string,…})

Returns:

(boolean) true

Or

(nil)

(table) Error description

get_schema ()

Get clusterwide DDL schema.

(Added in v1.2.0-28)

Returns:

(string) Schema in YAML format

Or

(nil)

(table) Error description

set_schema (schema)

Apply clusterwide DDL schema.

(Added in v1.2.0-28)

Parameters:

• schema: (string) in YAML format

Returns:

(string) The same new schema

Or

(nil)

(table) Error description

on_patch (trigger_new, trigger_old)

Set up trigger for for patch_clusterwide.

It will be executed before new new config applied.

If the parameters are (nil, old_trigger) , then the old trigger is deleted.

The trigger function is called with two argument: - conf_new ( ClusterwideConfig ) - conf_old ( ClusterWideConfig )

It is allowed to modify conf_new , but not conf_old . Return values are ignored. If calling a trigger raises an error, patch_clusterwide returns it as nil, err .

(Added in v2.1.0-4)

Parameters:

• trigger_new: (function)
• trigger_old: (function)

Usage:

local function inject_data(conf_new, _)
    local data_yml = yaml.encode({foo = 'bar'})
    conf_new:set_plaintext('data.yml', data_yml)
end)

twophase.on_patch(inject_data) -- set custom patch modifier trigger
twophase.on_patch(nil, inject_data) -- drop trigger

wait_config_release (timeout)

Wait until config won’t released.

Two-phase commit starts with config preparation. It’s just config pin into “vars.prepared_config”. After it using this value we could determine is two-phase commit is started or not. This function allows to wait when two-phase commit will be finished (successfully or not).

Parameters:

• timeout: (number)

Returns:

(boolean) true in case of success and false otherwise

prepare_2pc (upload_id)

Two-phase commit - preparation stage.

Validate the configuration and acquire a lock setting local variable and writing “config.prepare.yml” file. If the validation fails, the lock isn’t acquired and doesn’t have to be aborted.

Parameters:

• upload_id: (string)

Returns:

(boolean) true

Or

(nil)

(table) Error description

commit_2pc ()

Two-phase commit - commit stage.

Back up the active configuration, commit changes to filesystem by renaming prepared file, release the lock, and configure roles. If any errors occur, configuration is not rolled back automatically. Any problem encountered during this call has to be solved manually.

Returns:

(boolean) true

Or

(nil)

(table) Error description

abort_2pc ()

Two-phase commit - abort stage.

Release the lock for further commit attempts.

Returns:

(boolean) true