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--[[

Let a random number of transaction rollback

As part of the QA we have to verify that applications handle 
rollbacks nicely. To simulate a deadlock we turn client-side COMMITs
into server-side ROLLBACKs and return a ERROR packet to the client
telling it a deadlock happened.

--]]

function read_query(packet) 
	if packet:byte() ~= proxy.COM_QUERY then return end

	-- only care about commits 
	if packet:sub(2):upper() ~= "COMMIT" then return end

	-- let 80% fail
	if math.random(10) <= 5 then return end

	proxy.queries:append(1, string.char(proxy.COM_QUERY) .. "ROLLBACK", { resultset_is_needed = true })

	return proxy.PROXY_SEND_QUERY
end

function read_query_result(inj)
	if inj.id ~= 1 then return end

	proxy.response = {
		type = proxy.MYSQLD_PACKET_ERR,
		errmsg = "Lock wait timeout exceeded; try restarting transaction",
		errno = 1205,
		sqlstate = "HY000"
	}

	return proxy.PROXY_SEND_RESULT
end

