box.cfg{
    memtx_use_mvcc_engine = true
}

s = box.schema.create_space('s')
s:create_index('pk', {type = 'HASH', parts = {1, 'double'}})

fiber = require('fiber')

function unsigned(v)
    return v
end

function double(v)
    return require('ffi').cast('double', v)
end

function conflicting_fiber(cast_lookup_key, prefix, value)
    box.begin()

    -- This creates point hole items in different positions in the hash table
    -- depending on the cast function.
    print(prefix..'Check if {1} exists.')
    local key_exists = #s:select({cast_lookup_key(1)}) ~= 0

    if not key_exists then
        print(prefix..'No, {1} does not exist. Let others go.')
        fiber.sleep(0.25) -- Enough for WAL write of insert {1}.

        print(prefix..'Insert my unique value to abort on conflict.')
        s:insert({value})
    end

    box.commit()
end

print('[0] Create [1].')
f1 = fiber.new(conflicting_fiber, unsigned, '[1] ', 11)
f1:set_joinable(true)

print('[0] Create [2].')
f2 = fiber.new(conflicting_fiber, double, '[2] ', 22)
f2:set_joinable(true)

print('[0] Let [1] and [2] go.')
fiber.yield()

-- This only finds one point hole (one with double or unsigned key), so it only
-- conflicts one of conflicting fibers (must conflict both though).
print('[0] Inserting {1}...')
s:insert({1})

print('[0] Done, now [1] and [2] must be conflicting. The new space contents:')
print(require('yaml').encode(s:select(nil, {limit = 10})))

ok, result = f1:join() -- [0] must abort on commit.
print('[1]', ok, result)

ok, result = f2:join() -- [1] must abort on commit too, but does not.
print('[2]', ok, result)

os.exit()