Scripting examples

Minimal scenario

require("common")

function setup_tables(worker)
    worker:create_random_tables(5)
    worker:generate_initial_data()
end

function main(argv)
    args = argparser:parse(argv)
    conffile = parse_config(args)
    pgconfig = PgConf.new(conffile["default"])

    pgm = PgManager.new(pgconfig)
    pgm:setupAndStartPrimary()
    pgm.primaryNode:init(setup_tables)

    pg1 = pgm:get(1)

    t1 = pgm.primaryNode:initRandomWorkload({ run_seconds = 20, worker_count = 5 })
    t1:run()
    t1:wait_completion()
end

Custom arguments

A complete documentation for argparse is available at https://argparse.readthedocs.io/

-- could also be in main
argparser:option("-f --foo", "A sample option.", "bar")

function main(argv)
    args = argparser:parse(argv)
    info("Foo: " .. inspect(args["foo"]))
end

Simple postgres manager

It is easy and simple to setup (replicated) PostgreSQL using PgManager:

pgconfig = PgConf.new(conffile["default"])

pgm = PgManager.new(pgconfig)
pgm:setupAndStartPrimary()
pgm:setupAndStartAReplica()
-- can start additional replicas

primary = pgm:get(1)
replica = pgm:get(2)
-- ...

Background threads

The following example shows the background thread functionality:

-- global variables shouldn't be used: the values can be different in every thread
var = "foo";

-- functions defined in lua can be called in any thread
function dep()
    info("From dep(): var=" .. var)
end

function bg_thread()
    info("From bgt()")
    dep()

    for i=1,10 do
        -- the receive, receiveIfAny and send functions are special to background threads, 
        -- and used to communication with the creator thread
        msg = receive();

        info("Received message: " .. msg);

        if msg == "exit" then
            break;
        end;
    end
end

function main(argv)

    info("Starting background thread...")

    -- won't be reflected in the thread, do not depend on global state
    var = "bar"

    task = BackgroundThread.run("bglog", "bg_thread")

    info("While background thread running ... ")

    task:send("hey!")
    task:send("foo!")
    task:send("bar!")

    info("While background thread still running ... ")

    task:send("exit")

    task:join()

    info("All done")

end