--[[
Copyright (C) 2013-2014 Draios inc.

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License version 2 as
published by the Free Software Foundation.


This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
--]]

-- The number of items to show
HOW_MANY = 10

-- Chisel description
description = "Lists the " .. HOW_MANY .. " system calls that took the longest to return during the capture interval.";
short_description = "Slowest system calls";
category = "Performance";

-- Chisel argument list
args = {}

slow_calls = {}
last_lines = {}

-- Initialization callback
function on_init()
	-- Request the fields
	fevnum = chisel.request_field("evt.num")
	fevtime = chisel.request_field("evt.time")
	fevtype = chisel.request_field("evt.type")
	fevtargs = chisel.request_field("evt.args")
	flatency = chisel.request_field("evt.latency")
	fprname = chisel.request_field("proc.name")
	ftid = chisel.request_field("thread.tid")
	
	return true
end

-- Event parsing callback
function on_event()
	latency = evt.field(flatency)
	tid = evt.field(ftid)
	evtype = evt.field(fevtype)
	
	if evtype == "switch" then
		return true
	end
	
	if latency == 0 then
		prname = evt.field(fprname)
		if prname == nil then
			prname = ""
		end			
		line = string.format("%d) 0.%.9d %s (%d) > %s %s", evt.field(fevnum),
			0,
			prname,
			evt.field(ftid),
			evtype,
			evt.field(fevtargs))
		
		last_lines[tid] = line
	else
		for j = 1, HOW_MANY do
			if slow_calls[j] == nil or latency > slow_calls[j][1] then
				prname = evt.field(fprname)
				if prname == nil then
					prname = ""
				end
				
				line = string.format("%d) %d.%.9d %s (%d) < %s %s", evt.field(fevnum),
					latency / 1000000000,
					latency % 1000000000,
					prname, evt.field(ftid),
					evtype,
					evt.field(fevtargs))

				table.insert(slow_calls, j, {latency, last_lines[tid], line})
				break
			end
		end
		
		if #slow_calls > HOW_MANY then
			table.remove(slow_calls)
		end	
	end
	
	return true
end

-- Called by the engine at the end of the capture (Ctrl-C)
function on_capture_end()
	for j = 1, #slow_calls do
		print(slow_calls[j][2])
		print(slow_calls[j][3])
	end

	return true
end
