--
-- http://lua-users.org/wiki/PepperfishProfiler
--
-- == Introduction ==
--
-- Note that this requires os.clock(), debug.sethook(),
-- and debug.getinfo() or your equivalent replacements to
-- be available if this is an embedded application.
--
-- Example usage:
--
-- profiler = newProfiler()
-- profiler:start()
--
-- < call some functions that take time >
--
-- profiler:stop()
--
-- local outfile = io.open( "profile.txt", "w+" )
-- profiler:report( outfile )
-- outfile:close()
--
-- == Optionally choosing profiling method ==
--
-- The rest of this comment can be ignored if you merely want a good profiler.
--
-- newProfiler(method, sampledelay):
--
-- If method is omitted or "time", will profile based on real performance.
-- optionally, frequency can be provided to control the number of opcodes
-- per profiling tick. By default this is 100000, which (on my system) provides
-- one tick approximately every 2ms and reduces system performance by about 10%.
-- This can be reduced to increase accuracy at the cost of performance, or
-- increased for the opposite effect.
--
-- If method is "call", will profile based on function calls. Frequency is
-- ignored.
--
--
-- "time" may bias profiling somewhat towards large areas with "simple opcodes",
-- as the profiling function (which introduces a certain amount of unavoidable
-- overhead) will be called more often. This can be minimized by using a larger
-- sample delay - the default should leave any error largely overshadowed by
-- statistical noise. With a delay of 1000 I was able to achieve inaccuray of
-- approximately 25%. Increasing the delay to 100000 left inaccuracy below my
-- testing error.
--
-- "call" may bias profiling heavily towards areas with many function calls.
-- Testing found a degenerate case giving a figure inaccurate by approximately
-- 20,000%.  (Yes, a multiple of 200.) This is, however, more directly comparable
-- to common profilers (such as gprof) and also gives accurate function call
-- counts, which cannot be retrieved from "time".
--
-- I strongly recommend "time" mode, and it is now the default.
--
-- == History ==
--
-- 2008-09-16 - Time-based profiling and conversion to Lua 5.1
-- by Ben Wilhelm ( zorba-pepperfish@pavlovian.net ).
-- Added the ability to optionally choose profiling methods, along with a new
-- profiling method.
--
-- Converted to Lua 5, a few improvements, and
-- additional documentation by Tom Spilman ( tom@sickheadgames.com )
--
-- Additional corrections and tidying by original author
-- Daniel Silverstone ( dsilvers@pepperfish.net )
--
-- == Status ==
--
-- Daniel Silverstone is no longer using this code, and judging by how long it's
-- been waiting for Lua 5.1 support, I don't think Tom Spilman is either. I'm
-- perfectly willing to take on maintenance, so if you have problems or
-- questions, go ahead and email me :)
-- -- Ben Wilhelm ( zorba-pepperfish@pavlovian.net ) '
--
-- == Copyright ==
--
-- Lua profiler - Copyright Pepperfish 2002,2003,2004
--
-- Permission is hereby granted, free of charge, to any person obtaining a copy
-- of this software and associated documentation files (the "Software"), to
-- deal in the Software without restriction, including without limitation the
-- rights to use, copy, modify, merge, publish, distribute, and/or sell copies
-- of the Software, and to permit persons to whom the Software is furnished to
-- do so, subject to the following conditions:
--
-- The above copyright notice and this permission notice shall be included in
-- all copies or substantial portions of the Software.
--
-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
-- FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
-- IN THE SOFTWARE.
--

--
-- All profiler related stuff is stored in the top level table '_profiler'
--
_profiler = {}


--
-- newProfiler() creates a new profiler object for managing
-- the profiler and storing state.  Note that only one profiler
-- object can be executing at one time.
--
function newProfiler(variant, sampledelay)
	if _profiler.running then
		print("Profiler already running.")
		return
	end

	variant = variant or "time"

	if variant ~= "time" and variant ~= "call" then
		print("Profiler method must be 'time' or 'call'.")
		return
	end

	local newprof = {}
	for k,v in pairs(_profiler) do
		newprof[k] = v
	end
	newprof.variant = variant
	newprof.sampledelay = sampledelay or 100000
	return newprof
end


--
-- This function starts the profiler.  It will do nothing
-- if this (or any other) profiler is already running.
--
function _profiler.start(self)
	if _profiler.running then
		return
	end
	-- Start the profiler. This begins by setting up internal profiler state
	_profiler.running = self
	self.rawstats = {}
	self.callstack = {}
	if self.variant == "time" then
		self.lastclock = os.clock()
		debug.sethook( _profiler_hook_wrapper_by_time, "", self.sampledelay )
	elseif self.variant == "call" then
		debug.sethook( _profiler_hook_wrapper_by_call, "cr" )
	else
		print("Profiler method must be 'time' or 'call'.")
		sys.exit(1)
	end
end


--
-- This function stops the profiler.  It will do nothing
-- if a profiler is not running, and nothing if it isn't
-- the currently running profiler.
--
function _profiler.stop(self)
	if _profiler.running ~= self then
		return
	end
	-- Stop the profiler.
	debug.sethook( nil )
	_profiler.running = nil
end


--
-- Simple wrapper to handle the hook.  You should not
-- be calling this directly. Duplicated to reduce overhead.
--
function _profiler_hook_wrapper_by_call(action)
	if _profiler.running == nil then
		debug.sethook( nil )
	end
	_profiler.running:_internal_profile_by_call(action)
end
function _profiler_hook_wrapper_by_time(action)
	if _profiler.running == nil then
		debug.sethook( nil )
	end
	_profiler.running:_internal_profile_by_time(action)
end


--
-- This is the main by-function-call function of the profiler and should not
-- be called except by the hook wrapper
--
function _profiler._internal_profile_by_call(self,action)
	-- Since we can obtain the 'function' for the item we've had call us, we
	-- can use that...
	local caller_info = debug.getinfo( 3 )
	if caller_info == nil then
		print "No caller_info"
		return
	end

	--SHG_LOG("[_profiler._internal_profile] "..(caller_info.name or "<nil>"))

	-- Retrieve the most recent activation record...
	local latest_ar = nil
	if table.getn(self.callstack) > 0 then
		latest_ar = self.callstack[table.getn(self.callstack)]
	end

	-- Are we allowed to profile this function?
	local should_not_profile = 0
	for k,v in pairs(self.prevented_functions) do
		if k == caller_info.func then
			should_not_profile = v
		end
	end
	-- Also check the top activation record...
	if latest_ar then
		if latest_ar.should_not_profile == 2 then
			should_not_profile = 2
		end
	end

	-- Now then, are we in 'call' or 'return' ?
	-- print("Profile:", caller_info.name, "SNP:", should_not_profile,
	--       "Action:", action )
	if action == "call" then
		-- Making a call...
		local this_ar = {}
		this_ar.should_not_profile = should_not_profile
		this_ar.parent_ar = latest_ar
		this_ar.anon_child = 0
		this_ar.name_child = 0
		this_ar.children = {}
		this_ar.children_time = {}
		this_ar.clock_start = os.clock()
		-- Last thing to do on a call is to insert this onto the ar stack...
		table.insert( self.callstack, this_ar )
	else
		local this_ar = latest_ar
		if this_ar == nil then
			return -- No point in doing anything if no upper activation record
		end

		-- Right, calculate the time in this function...
		this_ar.clock_end = os.clock()
		this_ar.this_time = this_ar.clock_end - this_ar.clock_start

		-- Now, if we have a parent, update its call info...
		if this_ar.parent_ar then
			this_ar.parent_ar.children[caller_info.func] =
			(this_ar.parent_ar.children[caller_info.func] or 0) + 1
			this_ar.parent_ar.children_time[caller_info.func] =
			(this_ar.parent_ar.children_time[caller_info.func] or 0 ) +
			this_ar.this_time
			if caller_info.name == nil then
				this_ar.parent_ar.anon_child =
				this_ar.parent_ar.anon_child + this_ar.this_time
			else
				this_ar.parent_ar.name_child =
				this_ar.parent_ar.name_child + this_ar.this_time
			end
		end
		-- Now if we're meant to record information about ourselves, do so...
		if this_ar.should_not_profile == 0 then
			local inforec = self:_get_func_rec(caller_info.func,1)
			inforec.count = inforec.count + 1
			inforec.time = inforec.time + this_ar.this_time
			inforec.anon_child_time = inforec.anon_child_time + this_ar.anon_child
			inforec.name_child_time = inforec.name_child_time + this_ar.name_child
			inforec.func_info = caller_info
			for k,v in pairs(this_ar.children) do
				inforec.children[k] = (inforec.children[k] or 0) + v
				inforec.children_time[k] =
				(inforec.children_time[k] or 0) + this_ar.children_time[k]
			end
		end

		-- Last thing to do on return is to drop the last activation record...
		table.remove( self.callstack, table.getn( self.callstack ) )
	end
end


--
-- This is the main by-time internal function of the profiler and should not
-- be called except by the hook wrapper
--
function _profiler._internal_profile_by_time(self,action)
	-- we do this first so we add the minimum amount of extra time to this call
	local timetaken = os.clock() - self.lastclock

	local depth = 3
	local at_top = true
	local last_caller
	local caller = debug.getinfo(depth)
	while caller do
		if not caller.func then caller.func = "(tail call)" end
		if self.prevented_functions[caller.func] == nil then
			local info = self:_get_func_rec(caller.func, 1, caller)
			info.count = info.count + 1
			info.time = info.time + timetaken
			if last_caller then
				-- we're not the head, so update the "children" times also
				if last_caller.name then
					info.name_child_time = info.name_child_time + timetaken
				else
					info.anon_child_time = info.anon_child_time + timetaken
				end
				info.children[last_caller.func] =
				(info.children[last_caller.func] or 0) + 1
				info.children_time[last_caller.func] =
				(info.children_time[last_caller.func] or 0) + timetaken
			end
		end
		depth = depth + 1
		last_caller = caller
		caller = debug.getinfo(depth)
	end

	self.lastclock = os.clock()
end


--
-- This returns a (possibly empty) function record for
-- the specified function. It is for internal profiler use.
--
function _profiler._get_func_rec(self,func,force,info)
	-- Find the function ref for 'func' (if force and not present, create one)
	local ret = self.rawstats[func]
	if ret == nil and force ~= 1 then
		return nil
	end
	if ret == nil then
		-- Build a new function statistics table
		ret = {}
		ret.func = func
		ret.count = 0
		ret.time = 0
		ret.anon_child_time = 0
		ret.name_child_time = 0
		ret.children = {}
		ret.children_time = {}
		ret.func_info = info
		self.rawstats[func] = ret
	end
	return ret
end


--
-- This writes a profile report to the output file object.  If
-- sort_by_total_time is nil or false the output is sorted by
-- the function time minus the time in it's children.
--
function _profiler.report( self, outfile, sort_by_total_time )

	outfile:write
	[[Lua Profile output created by profiler.lua. Copyright Pepperfish 2002+

	]]

	-- This is pretty awful.
	local terms = {}
	if self.variant == "time" then
		terms.capitalized = "Sample"
		terms.single = "sample"
		terms.pastverb = "sampled"
	elseif self.variant == "call" then
		terms.capitalized = "Call"
		terms.single = "call"
		terms.pastverb = "called"
	else
		assert(false)
	end

	local total_time = 0
	local ordering = {}
	for func,record in pairs(self.rawstats) do
		table.insert(ordering, func)
	end

	if sort_by_total_time then
		table.sort( ordering,
		function(a,b) return self.rawstats[a].time > self.rawstats[b].time end
		)
	else
		table.sort( ordering,
		function(a,b)
			local arec = self.rawstats[a]
			local brec = self.rawstats[b]
			local atime = arec.time - (arec.anon_child_time + arec.name_child_time)
			local btime = brec.time - (brec.anon_child_time + brec.name_child_time)
			return atime > btime
		end
		)
	end

	for i=1,#ordering do
		local func = ordering[i]
		local record = self.rawstats[func]
		local thisfuncname = " " .. self:_pretty_name(func) .. " "
		if string.len( thisfuncname ) < 42 then
			thisfuncname = string.rep( "-", math.floor((42 - string.len(thisfuncname))/2) ) .. thisfuncname
			thisfuncname = thisfuncname .. string.rep( "-", 42 - string.len(thisfuncname) )
		end

		total_time = total_time + ( record.time - ( record.anon_child_time +
		record.name_child_time ) )
		outfile:write( string.rep( "-", 19 ) .. thisfuncname ..
		string.rep( "-", 19 ) .. "\n" )
		outfile:write( terms.capitalized.." count:         " ..
		string.format( "%4d", record.count ) .. "\n" )
		outfile:write( "Time spend total:       " ..
		string.format( "%4.3f", record.time ) .. "s\n" )
		outfile:write( "Time spent in children: " ..
		string.format("%4.3f",record.anon_child_time+record.name_child_time) ..
		"s\n" )
		local timeinself =
		record.time - (record.anon_child_time + record.name_child_time)
		outfile:write( "Time spent in self:     " ..
		string.format("%4.3f", timeinself) .. "s\n" )
		outfile:write( "Time spent per " .. terms.single .. ":  " ..
		string.format("%4.5f", record.time/record.count) ..
		"s/" .. terms.single .. "\n" )
		outfile:write( "Time spent in self per "..terms.single..": " ..
		string.format( "%4.5f", timeinself/record.count ) .. "s/" ..
		terms.single.."\n" )

		-- Report on each child in the form
		-- Child  <funcname> called n times and took a.bs
		local added_blank = 0
		for k,v in pairs(record.children) do
			if self.prevented_functions[k] == nil or
				self.prevented_functions[k] == 0
				then
					if added_blank == 0 then
						outfile:write( "\n" ) -- extra separation line
						added_blank = 1
					end
					outfile:write( "Child " .. self:_pretty_name(k) ..
					string.rep( " ", 41-string.len(self:_pretty_name(k)) ) .. " " ..
					terms.pastverb.." " .. string.format("%6d", v) )
					outfile:write( " times. Took " ..
					string.format("%4.2f", record.children_time[k] ) .. "s\n" )
				end
			end

			outfile:write( "\n" ) -- extra separation line
			outfile:flush()
		end
		outfile:write( "\n\n" )
		outfile:write( "Total time spent in profiled functions: " ..
		string.format("%5.3g",total_time) .. "s\n" )
		outfile:write( [[

	END
	]] )
	outfile:flush()
end


--
-- This writes the profile to the output file object as
-- loadable Lua source.
--
function _profiler.lua_report(self,outfile)
	-- Purpose: Write out the entire raw state in a cross-referenceable form.
	local ordering = {}
	local functonum = {}
	for func,record in pairs(self.rawstats) do
		table.insert(ordering, func)
		functonum[func] = table.getn(ordering)
	end

	outfile:write(
	"-- Profile generated by profiler.lua Copyright Pepperfish 2002+\n\n" )
	outfile:write( "-- Function names\nfuncnames = {}\n" )
	for i=1,table.getn(ordering) do
		local thisfunc = ordering[i]
		outfile:write( "funcnames[" .. i .. "] = " ..
		string.format("%q", self:_pretty_name(thisfunc)) .. "\n" )
	end
	outfile:write( "\n" )
	outfile:write( "-- Function times\nfunctimes = {}\n" )
	for i=1,table.getn(ordering) do
		local thisfunc = ordering[i]
		local record = self.rawstats[thisfunc]
		outfile:write( "functimes[" .. i .. "] = { " )
		outfile:write( "tot=" .. record.time .. ", " )
		outfile:write( "achild=" .. record.anon_child_time .. ", " )
		outfile:write( "nchild=" .. record.name_child_time .. ", " )
		outfile:write( "count=" .. record.count .. " }\n" )
	end
	outfile:write( "\n" )
	outfile:write( "-- Child links\nchildren = {}\n" )
	for i=1,table.getn(ordering) do
		local thisfunc = ordering[i]
		local record = self.rawstats[thisfunc]
		outfile:write( "children[" .. i .. "] = { " )
		for k,v in pairs(record.children) do
			if functonum[k] then -- non-recorded functions will be ignored now
				outfile:write( functonum[k] .. ", " )
			end
		end
		outfile:write( "}\n" )
	end
	outfile:write( "\n" )
	outfile:write( "-- Child call counts\nchildcounts = {}\n" )
	for i=1,table.getn(ordering) do
		local thisfunc = ordering[i]
		local record = self.rawstats[thisfunc]
		outfile:write( "children[" .. i .. "] = { " )
		for k,v in record.children do
			if functonum[k] then -- non-recorded functions will be ignored now
				outfile:write( v .. ", " )
			end
		end
		outfile:write( "}\n" )
	end
	outfile:write( "\n" )
	outfile:write( "-- Child call time\nchildtimes = {}\n" )
	for i=1,table.getn(ordering) do
		local thisfunc = ordering[i]
		local record = self.rawstats[thisfunc];
		outfile:write( "children[" .. i .. "] = { " )
		for k,v in pairs(record.children) do
			if functonum[k] then -- non-recorded functions will be ignored now
				outfile:write( record.children_time[k] .. ", " )
			end
		end
		outfile:write( "}\n" )
	end
	outfile:write( "\n\n-- That is all.\n\n" )
	outfile:flush()
end

-- Internal function to calculate a pretty name for the profile output
function _profiler._pretty_name(self,func)

	-- Only the data collected during the actual
	-- run seems to be correct.... why?
	local info = self.rawstats[ func ].func_info
	-- local info = debug.getinfo( func )

	local name = ""
	if info.what == "Lua" then
		name = "L:"
	end
	if info.what == "C" then
		name = "C:"
	end
	if info.what == "main" then
		name = " :"
	end

	if info.name == nil then
		name = name .. "<"..tostring(func) .. ">"
	else
		name = name .. info.name
	end

	if info.source then
		name = name
	else
		if info.what == "C" then
			name = name .. "@?"
		else
			name = name .. "@<string>"
		end
	end
	name = name .. ":"
	if info.what == "C" then
		name = name .. "?"
	else
		name = name .. info.linedefined
	end

	return name
end


--
-- This allows you to specify functions which you do
-- not want profiled.  Setting level to 1 keeps the
-- function from being profiled.  Setting level to 2
-- keeps both the function and its children from
-- being profiled.
--
-- BUG: 2 will probably act exactly like 1 in "time" mode.
-- If anyone cares, let me (zorba) know and it can be fixed.
--
function _profiler.prevent(self, func, level)
	self.prevented_functions[func] = (level or 1)
end


_profiler.prevented_functions = {
	[_profiler.start] = 2,
	[_profiler.stop] = 2,
	[_profiler._internal_profile_by_time] = 2,
	[_profiler._internal_profile_by_call] = 2,
	[_profiler_hook_wrapper_by_time] = 2,
	[_profiler_hook_wrapper_by_call] = 2,
	[_profiler.prevent] = 2,
	[_profiler._get_func_rec] = 2,
	[_profiler.report] = 2,
	[_profiler.lua_report] = 2,
	[_profiler._pretty_name] = 2
}
