%%
%% %CopyrightBegin%
%% 
  Copyright Ericsson AB 1996 - 2009 . All Rights Reserved .
%% 
  The contents of this file are subject to the Erlang Public License ,
  Version 1.1 , ( the " License " ) ; you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at /.
%% 
  Software distributed under the License is distributed on an " AS IS "
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%% 
%% %CopyrightEnd%
%%
-module(memsup).
-behaviour(gen_server).

%% API
-export([start_link/0]). % for supervisor
-export([get_memory_data/0, get_system_memory_data/0,
	 get_check_interval/0, set_check_interval/1,
	 get_procmem_high_watermark/0, set_procmem_high_watermark/1,
	 get_sysmem_high_watermark/0, set_sysmem_high_watermark/1,
	 get_helper_timeout/0, set_helper_timeout/1,
	 get_os_wordsize/0]).
-export([dummy_reply/1, param_type/2, param_default/1]).

%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
	 terminate/2, code_change/3]).

%% Other exports
-export([format_status/2]).

-include("memsup.hrl").

-record(state,
	{os,                  % {OSfamily,OSname} | OSfamily
	 port_mode,           % bool()

  undefined | { Alloc , Total }
  undefined | { Pid , Alloc }

	 sys_only,            % bool()  memsup_system_only
	 timeout,             % int()   memory_check_interval, ms
	 helper_timeout,      % int()   memsup_helper_timeout, ms
	 sys_mem_watermark,   % float() system_memory_high_watermark, %
  float ( )  , %

	 pid,                 % undefined | pid()
	 wd_timer,            % undefined | TimerRef
	 ext_wd_timer,        % undefined | TimerRef
	 pending = [],        % [reg | {reg,From} | {ext,From}]
	 ext_pending = []     % [{ext,From}]
	}).

%%----------------------------------------------------------------------
%% API
%%----------------------------------------------------------------------

start_link() ->
    gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).

get_os_wordsize() ->
    os_mon:call(memsup, get_os_wordsize, infinity).

get_memory_data() ->
    os_mon:call(memsup, get_memory_data, infinity).

get_system_memory_data() ->
    os_mon:call(memsup, get_system_memory_data, infinity).

get_check_interval() ->
    os_mon:call(memsup, get_check_interval, infinity).
set_check_interval(Minutes) ->
    case param_type(memory_check_interval, Minutes) of
	true ->
	    MS = minutes_to_ms(Minutes), % for backwards compatibility
	    os_mon:call(memsup, {set_check_interval, MS}, infinity);
	false ->
	    erlang:error(badarg)
    end.

get_procmem_high_watermark() ->
    os_mon:call(memsup, get_procmem_high_watermark, infinity).
set_procmem_high_watermark(Float) ->
    case param_type(process_memory_high_watermark, Float) of
	true ->
	    os_mon:call(memsup, {set_procmem_high_watermark, Float},
			infinity);
	false ->
	    erlang:error(badarg)
    end.

get_sysmem_high_watermark() ->
    os_mon:call(memsup, get_sysmem_high_watermark, infinity).
set_sysmem_high_watermark(Float) ->
    case param_type(system_memory_high_watermark, Float) of
	true ->
	    os_mon:call(memsup, {set_sysmem_high_watermark, Float},
			infinity);
	false ->
	    erlang:error(badarg)
    end.

get_helper_timeout() ->
    os_mon:call(memsup, get_helper_timeout, infinity).
set_helper_timeout(Seconds) ->
    case param_type(memsup_helper_timeout, Seconds) of
	true ->
	    os_mon:call(memsup, {set_helper_timeout, Seconds});
	false ->
	    erlang:error(badarg)
    end.

dummy_reply(get_memory_data) ->
    dummy_reply(get_memory_data,
		os_mon:get_env(memsup, memsup_system_only));
dummy_reply(get_system_memory_data) ->
    [];
dummy_reply(get_os_wordsize) ->
    0;
dummy_reply(get_check_interval) ->
    minutes_to_ms(os_mon:get_env(memsup, memory_check_interval));
dummy_reply({set_check_interval, _}) ->
    ok;
dummy_reply(get_procmem_high_watermark) ->
    trunc(100 * os_mon:get_env(memsup, process_memory_high_watermark));
dummy_reply({set_procmem_high_watermark, _}) ->
    ok;
dummy_reply(get_sysmem_high_watermark) ->
    trunc(100 * os_mon:get_env(memsup, system_memory_high_watermark));
dummy_reply({set_sysmem_high_watermark, _}) ->
    ok;
dummy_reply(get_helper_timeout) ->
    os_mon:get_env(memsup, memsup_helper_timeout);
dummy_reply({set_helper_timeout, _}) ->
    ok.
dummy_reply(get_memory_data, true) ->
    {0,0,undefined};
dummy_reply(get_memory_data, false) ->
    {0,0,{self(),0}}.

param_type(memsup_system_only, Val) when Val==true; Val==false -> true;
param_type(memory_check_interval, Val) when is_integer(Val),
                                            Val>0 -> true;
param_type(memsup_helper_timeout, Val) when is_integer(Val),
                                            Val>0 -> true;
param_type(system_memory_high_watermark, Val) when is_number(Val),
						   0=<Val,
						   Val=<1 -> true;
param_type(process_memory_high_watermark, Val) when is_number(Val),
						    0=<Val,
						    Val=<1 -> true;
param_type(_Param, _Val) -> false.

param_default(memsup_system_only) -> false;
param_default(memory_check_interval) -> 1;
param_default(memsup_helper_timeout) -> 30;
param_default(system_memory_high_watermark) -> 0.80;
param_default(process_memory_high_watermark) -> 0.05.

%%----------------------------------------------------------------------
%% gen_server callbacks
%%----------------------------------------------------------------------

init([]) ->
    process_flag(trap_exit, true),
    process_flag(priority, low),

    OS = os:type(),
    PortMode = case OS of
		   {unix, darwin} -> false;
		   {unix, freebsd} -> false;
		   % Linux supports this.
		   {unix, linux} -> true;
		   {unix, openbsd} -> true;
		   {unix, irix64} -> true;
		   {unix, irix} -> true;
		   {unix, sunos} -> true;
		   {win32, _OSname} -> false;
		   vxworks -> true;
		   _ ->
		       exit({unsupported_os, OS})
	       end,
    Pid = if
	      PortMode ->
		  spawn_link(fun() -> port_init() end);
	      not PortMode ->
		  undefined
	  end,

    %% Read the values of some configuration parameters
    SysOnly = os_mon:get_env(memsup, memsup_system_only),
    Timeout = os_mon:get_env(memsup, memory_check_interval),
    HelperTimeout = os_mon:get_env(memsup, memsup_helper_timeout),
    SysMem = os_mon:get_env(memsup, system_memory_high_watermark),
    ProcMem = os_mon:get_env(memsup, process_memory_high_watermark),

    %% Initiate first data collection
    self() ! time_to_collect,

    {ok, #state{os=OS, port_mode=PortMode,

		sys_only           = SysOnly,
		timeout            = minutes_to_ms(Timeout),
		helper_timeout     = sec_to_ms(HelperTimeout),
		sys_mem_watermark  = SysMem,
		proc_mem_watermark = ProcMem,

		pid=Pid}}.

handle_call(get_os_wordsize, _From, State) ->
    Wordsize = get_os_wordsize(State#state.os),
    {reply, Wordsize, State};
handle_call(get_memory_data, From, State) ->
    %% Return result of latest memory check
    case State#state.mem_usage of
	{Alloc, Total} ->
	    Worst = State#state.worst_mem_user,
	    {reply, {Total, Alloc, Worst}, State};
	
	%% Special case: get_memory_data called before any memory data
	%% has been collected
	undefined ->
	    case State#state.wd_timer of
		undefined ->
		    WDTimer = erlang:send_after(State#state.timeout,
						self(),
						reg_collection_timeout),
		    Pending = [{reg,From}],
		    if
			State#state.port_mode ->
			    State#state.pid ! {self(), collect_sys},
			    {noreply, State#state{wd_timer=WDTimer,
						  pending=Pending}};
			true ->
			    OS = State#state.os,
			    Self = self(),
			    Pid = spawn_link(fun() ->
						     MU = get_memory_usage(OS),
						     Self ! {collected_sys,MU}
					     end),
			    {noreply, State#state{pid=Pid,
						  wd_timer=WDTimer,
						  pending=Pending}}
		    end;
		_TimerRef ->
		    Pending = [{reg,From} | State#state.pending],
		    {noreply, State#state{pending=Pending}}
	    end
    end;

handle_call(get_system_memory_data,From,#state{port_mode=true}=State) ->
    %% When using a port, the extensive memory collection is slightly
  different than a regular one
    case State#state.ext_wd_timer of
	undefined ->
	    WDTimer = erlang:send_after(State#state.helper_timeout,
					self(),
					ext_collection_timeout),
	    State#state.pid ! {self(), collect_ext_sys},
	    {noreply, State#state{ext_wd_timer=WDTimer,
				  ext_pending=[{ext,From}]}};
	_TimerRef ->
	    Pending = [{ext,From} | State#state.ext_pending],
	    {noreply, State#state{ext_pending=Pending}}
    end;
handle_call(get_system_memory_data, From, State) ->
    %% When not using a port, the regular memory collection is used
    %% for extensive memory data as well
    case State#state.wd_timer of
	undefined ->
	    WDTimer = erlang:send_after(State#state.helper_timeout,
					self(),
					reg_collection_timeout),
	    OS = State#state.os,
	    Self = self(),
	    Pid = spawn_link(fun() ->
				     MemUsage = get_memory_usage(OS),
				     Self ! {collected_sys, MemUsage}
			     end),
	    {noreply, State#state{pid=Pid, wd_timer=WDTimer,
				  pending=[{ext,From}]}};
	_TimerRef ->
	    Pending = [{ext,From} | State#state.pending],
	    {noreply, State#state{pending=Pending}}
    end;

handle_call(get_check_interval, _From, State) ->
    {reply, State#state.timeout, State};
handle_call({set_check_interval, MS}, _From, State) ->
    {reply, ok, State#state{timeout=MS}};

handle_call(get_procmem_high_watermark, _From, State) ->
    {reply, trunc(100 * State#state.proc_mem_watermark), State};
handle_call({set_procmem_high_watermark, Float}, _From, State) ->
    {reply, ok, State#state{proc_mem_watermark=Float}};

handle_call(get_sysmem_high_watermark, _From, State) ->
    {reply, trunc(100 * State#state.sys_mem_watermark), State};
handle_call({set_sysmem_high_watermark, Float}, _From, State) ->
    {reply, ok, State#state{sys_mem_watermark=Float}};

handle_call(get_helper_timeout, _From, State) ->
    {reply, ms_to_sec(State#state.helper_timeout), State};
handle_call({set_helper_timeout, Seconds}, _From, State) ->
    {reply, ok, State#state{helper_timeout=sec_to_ms(Seconds)}};

  The following are only for test purposes ( whitebox testing ) .
handle_call({set_sys_hw, HW}, _From, State) ->
    {reply, ok, State#state{sys_mem_watermark=HW}};
handle_call({set_pid_hw, HW}, _From, State) ->
    {reply, ok, State#state{proc_mem_watermark=HW}};
handle_call(get_state, _From, State) ->
    {reply, State, State}.

handle_cast(_Msg, State) ->
    {noreply, State}.

%% It's time to check memory
handle_info(time_to_collect, State) ->
    case State#state.wd_timer of
	undefined ->
	    WDTimer = erlang:send_after(State#state.helper_timeout,
					self(),
					reg_collection_timeout),
	    if
		State#state.port_mode ->
		    State#state.pid ! {self(), collect_sys},
		    {noreply, State#state{wd_timer=WDTimer,
					  pending=[reg]}};
		true ->
		    OS = State#state.os,
		    Self = self(),
		    Pid = spawn_link(fun() ->
					     MU = get_memory_usage(OS),
					     Self ! {collected_sys,MU}
				     end),
		    {noreply, State#state{pid=Pid, wd_timer=WDTimer,
					  pending=[reg]}}
	    end;
	_TimerRef ->
	    {noreply, State#state{pending=[reg|State#state.pending]}}
    end;

%% Memory data collected
handle_info({collected_sys, {Alloc,Total}}, State) ->

  Cancel watchdog timer ( and as a security measure ,
    %% also flush any reg_collection_timeout message)
    TimeSpent = case erlang:cancel_timer(State#state.wd_timer) of
		    false ->
			State#state.helper_timeout;
		    TimeLeft ->
			State#state.helper_timeout-TimeLeft
		end,
    flush(reg_collection_timeout),

  First check if this is the result of a periodic memory check
  and update alarms and State if this is the case
    State2 =
	case lists:member(reg, State#state.pending) of
	    true ->

		%% Check if system alarm should be set/cleared
		if
		    Alloc > State#state.sys_mem_watermark*Total ->
			set_alarm(system_memory_high_watermark, []);
		    true ->
			clear_alarm(system_memory_high_watermark)
		end,

		%% Check if process data should be collected
		case State#state.sys_only of
		    false ->
			{Pid, Bytes} = get_worst_memory_user(),
			Threshold= State#state.proc_mem_watermark*Total,

			%% Check if process alarm should be set/cleared
			if
			    Bytes > Threshold ->
				set_alarm(process_memory_high_watermark,
					  Pid);
			    true ->
				clear_alarm(process_memory_high_watermark)
			end,
			
			State#state{mem_usage={Alloc, Total},
				    worst_mem_user={Pid, Bytes}};
		    true ->
			State#state{mem_usage={Alloc, Total}}
		end;
	    false ->
		State
	end,

    %% Then send a reply to all waiting clients, in preserved time order
    Worst = State2#state.worst_mem_user,
    SysMemUsage = get_ext_memory_usage(State2#state.os, {Alloc,Total}),
    reply(State2#state.pending, {Total,Alloc,Worst}, SysMemUsage),

    %% Last, if this was a periodic check, start a timer for the next
    %% one. New timeout = interval-time spent collecting,
    case lists:member(reg, State#state.pending) of
	true ->
	    Time = case State2#state.timeout - TimeSpent of
		       MS when MS<0 ->
			   0;
		       MS ->
			   MS
		   end,
	    erlang:send_after(Time, self(), time_to_collect);
	false ->
	    ignore
    end,
    {noreply, State2#state{wd_timer=undefined, pending=[]}};
handle_info({'EXIT', Pid, normal}, State) when is_pid(Pid) ->
  Temporary pid terminating when job is done
    {noreply, State};

  Timeout during data collection
handle_info(reg_collection_timeout, State) ->

  Cancel memory collection ( and as a security measure ,
  also flush any collected_sys message )
    if
	State#state.port_mode -> State#state.pid ! cancel;
	true -> exit(State#state.pid, cancel)
    end,
    flush(collected_sys),

    %% Issue a warning message
    Str = "OS_MON (memsup) timeout, no data collected~n",
    error_logger:warning_msg(Str),

    %% Send a dummy reply to all waiting clients, preserving time order
    reply(State#state.pending,
	  dummy_reply(get_memory_data, State#state.sys_only),
	  dummy_reply(get_system_memory_data)),

    %% If it is a periodic check which has timed out, start a timer for
  the next one
    %% New timeout = interval-helper timeout
    case lists:member(reg, State#state.pending) of
	true ->
	    Time =
		case State#state.timeout-State#state.helper_timeout of
		    MS when MS<0 -> 0;
		    MS -> MS
		end,
	    erlang:send_after(Time, self(), time_to_collect);
	false ->
	    ignore
    end,
    {noreply, State#state{wd_timer=undefined, pending=[]}};
handle_info({'EXIT', Pid, cancel}, State) when is_pid(Pid) ->
  Temporary pid terminating as ordered
    {noreply, State};

%% Extensive memory data collected (port_mode==true only)
handle_info({collected_ext_sys, SysMemUsage}, State) ->

  Cancel watchdog timer ( and as a security mearure ,
    %% also flush any ext_collection_timeout message)
    erlang:cancel_timer(State#state.ext_wd_timer),
    flush(ext_collection_timeout),

    %% Send the reply to all waiting clients, preserving time order
    reply(State#state.ext_pending, undef, SysMemUsage),

    {noreply, State#state{ext_wd_timer=undefined, ext_pending=[]}};

  Timeout during ext memory data collection ( port_mode==true only )
handle_info(ext_collection_timeout, State) ->

  Cancel memory collection ( and as a security measure ,
    %% also flush any collected_ext_sys message)
    State#state.pid ! ext_cancel,
    flush(collected_ext_sys),

    %% Issue a warning message
    Str = "OS_MON (memsup) timeout, no data collected~n",
    error_logger:warning_msg(Str),

    %% Send a dummy reply to all waiting clients, preserving time order
    SysMemUsage = dummy_reply(get_system_memory_data),
    reply(State#state.ext_pending, undef, SysMemUsage),

    {noreply, State#state{ext_wd_timer=undefined, ext_pending=[]}};

%% Error in data collecting (port connected or temporary) process
handle_info({'EXIT', Pid, Reason}, State) when is_pid(Pid) ->
    {stop, Reason, State};
	    
handle_info(_Info, State) ->
    {noreply, State}.

terminate(_Reason, State) ->
    if
	State#state.port_mode -> State#state.pid ! close;
	true -> ok
    end,
    clear_alarms(),
    ok.

%% os_mon-2.0.1
%% For live downgrade to/upgrade from os_mon-1.8[.1] and -2.0
code_change(Vsn, PrevState, "1.8") ->
    case Vsn of

	%% Downgrade from this version
	{down, _Vsn} ->

	    %% Kill the helper process, if there is one,
	    %% and flush messages from it
	    case PrevState#state.pid of
		Pid when is_pid(Pid) ->
  to prevent ' EXIT ' message
		    exit(Pid, cancel);
		undefined -> ignore
	    end,
	    flush(collected_sys),
	    flush(collected_ext_sys),

	    %% Cancel timers, flush timeout messages
	    %% and send dummy replies to any pending clients
	    case PrevState#state.wd_timer of
		undefined ->
		    ignore;
		TimerRef1 ->
		    erlang:cancel_timer(TimerRef1),
		    SysOnly = PrevState#state.sys_only,
		    MemUsage = dummy_reply(get_memory_data, SysOnly),
		    SysMemUsage1 = dummy_reply(get_system_memory_data),
		    reply(PrevState#state.pending,MemUsage,SysMemUsage1)
	    end,
	    case PrevState#state.ext_wd_timer of
		undefined ->
		    ignore;
		TimerRef2 ->
		    erlang:cancel_timer(TimerRef2),
		    SysMemUsage2 = dummy_reply(get_system_memory_data),
		    reply(PrevState#state.pending, undef, SysMemUsage2)
	    end,
	    flush(reg_collection_timeout),
	    flush(ext_collection_timeout),

	    %% Downgrade to old state record
	    State = {state,
		     PrevState#state.timeout,
		     PrevState#state.mem_usage,
		     PrevState#state.worst_mem_user,
		     PrevState#state.sys_mem_watermark,
		     PrevState#state.proc_mem_watermark,
  collect_procmem
		     undefined, % wd_timer
		     [],        % pending
		     undefined, % ext_wd_timer
		     [],        % ext_pending
		     PrevState#state.helper_timeout},
	    {ok, State};

	%% Upgrade to this version
	_Vsn ->

	    %% Old state record
	    {state,
	     Timeout, MemUsage, WorstMemUser,
	     SysMemWatermark, ProcMemWatermark, CollProc,
	     WDTimer, Pending, ExtWDTimer, ExtPending,
	     HelperTimeout} = PrevState,
	    SysOnly = not CollProc,

	    %% Flush memsup_helper messages
	    flush(collected_sys),
	    flush(collected_proc),
	    flush(collected_ext_sys),
		     
	    %% Cancel timers, flush timeout messages
	    %% and send dummy replies to any pending clients
	    case WDTimer of
		undefined ->
		    ignore;
		TimerRef1 ->
		    erlang:cancel_timer(TimerRef1),
		    MemUsage = dummy_reply(get_memory_data, SysOnly),
		    Pending2 = lists:map(fun(From) -> {reg,From} end,
					 Pending),
		    reply(Pending2, MemUsage, undef)
	    end,
	    case ExtWDTimer of
		undefined ->
		    ignore;
		TimerRef2 ->
		    erlang:cancel_timer(TimerRef2),
		    SysMemUsage = dummy_reply(get_system_memory_data),
		    ExtPending2 = lists:map(fun(From) -> {ext,From} end,
					    ExtPending),
		    reply(ExtPending2, undef, SysMemUsage)
	    end,
	    flush(reg_collection_timeout),
	    flush(ext_collection_timeout),

	    OS = os:type(),
	    PortMode = case OS of
			   {unix, darwin} -> false;
			   {unix, freebsd} -> false;
			   {unix, linux} -> false;
			   {unix, openbsd} -> true;
			   {unix, sunos} -> true;
			   {win32, _OSname} -> false;
			   vxworks -> true
		       end,
	    Pid = if
		      PortMode -> spawn_link(fun() -> port_init() end);
		      not PortMode -> undefined
		  end,

	    %% Upgrade to this state record
	    State = #state{os = OS,
			   port_mode = PortMode,
			   mem_usage = MemUsage,
			   worst_mem_user = WorstMemUser,
			   sys_only  = SysOnly,
			   timeout         = Timeout,
			   helper_timeout  = HelperTimeout,
			   sys_mem_watermark = SysMemWatermark,
			   proc_mem_watermark = ProcMemWatermark,
			   pid                = Pid,
			   wd_timer           = undefined,
			   ext_wd_timer       = undefined,
			   pending            = [],
			   ext_pending        = []},
	    {ok, State}
    end;
code_change(_Vsn, State, "2.0") ->

    %% Restart the port process (it must use new memsup code)
    Pid = case State#state.port_mode of
	      true ->
		  State#state.pid ! close,
		  spawn_link(fun() -> port_init() end);
	      false ->
		  State#state.pid
	  end,
    {ok, State#state{pid=Pid}};
	  
code_change(_OldVsn, State, _Extra) ->
    {ok, State}.

%%----------------------------------------------------------------------
%% Other exports
%%----------------------------------------------------------------------

format_status(_Opt, [_PDict, #state{timeout=Timeout, mem_usage=MemUsage,
				    worst_mem_user=WorstMemUser}]) ->
    {Allocated, Total} = MemUsage,
    WorstMemFormat = case WorstMemUser of
			 {Pid, Mem} ->
			     [{"Pid", Pid}, {"Memory", Mem}];
			 undefined ->
			     undefined
		     end,
    [{data, [{"Timeout", Timeout}]},
     {items, {"Memory Usage", [{"Allocated", Allocated},
			       {"Total", Total}]}},
     {items, {"Worst Memory User", WorstMemFormat}}].


%%----------------------------------------------------------------------
  Internal functions
%%----------------------------------------------------------------------

%%-- Fetching kernel bit support ---------------------------------------

get_os_wordsize({unix, sunos}) ->
    String = clean_string(os:cmd("isainfo -b")),
    erlang:list_to_integer(String);
get_os_wordsize({unix, irix64})  -> 64;
get_os_wordsize({unix, irix})    -> 32;
get_os_wordsize({unix, linux})   -> get_os_wordsize_with_uname();
get_os_wordsize({unix, darwin})  -> get_os_wordsize_with_uname();
get_os_wordsize({unix, netbsd})  -> get_os_wordsize_with_uname();
get_os_wordsize({unix, freebsd}) -> get_os_wordsize_with_uname();
get_os_wordsize({unix, openbsd}) -> get_os_wordsize_with_uname();
get_os_wordsize(_)               -> unsupported_os.

get_os_wordsize_with_uname() ->
    String = clean_string(os:cmd("uname -m")),
    case String of
	"x86_64"  -> 64;
	"sparc64" -> 64;
	_         -> 32
    end.

clean_string(String) -> lists:flatten(string:tokens(String,"\r\n\t ")).
    

%%--Replying to pending clients-----------------------------------------

reply(Pending, MemUsage, SysMemUsage) ->
    lists:foreach(fun(reg) ->
			  ignore;
		     ({reg, From}) ->
			  gen_server:reply(From, MemUsage);
		     ({ext, From}) ->
			  gen_server:reply(From, SysMemUsage)
		  end,
		  lists:reverse(Pending)).

%%--Collect memory data, no port----------------------------------------

%% get_memory_usage(OS) -> {Alloc, Total}

   :
%% Uses vm_stat command. This appears to lie about the page size in
  Mac OS X 10.2.2 - the pages given are based on 4000 bytes , but
  the vm_stat command tells us that it is 4096 ...
get_memory_usage({unix,darwin}) ->
    Str = os:cmd("/usr/bin/vm_stat"),
    {ok, [Free],Str2} = io_lib:fread("Pages free:~d.",skip_to_eol(Str)),
    {ok, [Active],Str3} =
	io_lib:fread("Pages active:~d.", skip_to_eol(Str2)),
    {ok, [Inactive],Str4} =
	io_lib:fread("Pages inactive:~d.", skip_to_eol(Str3)),
    {ok, [Wired],_} =
	io_lib:fread("Pages wired down:~d.", skip_to_eol(Str4)),
    NMemUsed  = (Wired + Active + Inactive) * 4000,
    NMemTotal = NMemUsed + Free * 4000,
    {NMemUsed,NMemTotal};

%% FreeBSD: Look in /usr/include/sys/vmmeter.h for the format of struct
%% vmmeter
get_memory_usage({unix,freebsd}) ->
    PageSize  = freebsd_sysctl("vm.stats.vm.v_page_size"),
    PageCount = freebsd_sysctl("vm.stats.vm.v_page_count"),
    FreeCount = freebsd_sysctl("vm.stats.vm.v_free_count"),
    NMemUsed  = (PageCount - FreeCount) * PageSize,
    NMemTotal = PageCount * PageSize,
    {NMemUsed, NMemTotal};

%% Win32: Find out how much memory is in use by asking
%% the os_mon_sysinfo process.
get_memory_usage({win32,_OSname}) ->
    [Result|_] = os_mon_sysinfo:get_mem_info(),
    {ok, [_MemLoad, TotPhys, AvailPhys,
	  _TotPage, _AvailPage, _TotV, _AvailV], _RestStr} =
	io_lib:fread("~d~d~d~d~d~d~d", Result),
    {TotPhys-AvailPhys, TotPhys}.

skip_to_eol([]) ->
    [];
skip_to_eol([$\n | T]) ->
    T;
skip_to_eol([_ | T]) ->
    skip_to_eol(T).

freebsd_sysctl(Def) ->
    list_to_integer(os:cmd("/sbin/sysctl -n " ++ Def) -- "\n").

  get_ext_memory_usage(OS , { Alloc , Total } ) - > [ { Tag , Bytes } ]
get_ext_memory_usage(OS, {Alloc, Total}) ->
    case OS of
	{win32, _} ->
	    [{total_memory, Total}, {free_memory, Total-Alloc},
	     {system_total_memory, Total}];
	{unix, linux} ->
	    [{total_memory, Total}, {free_memory, Total-Alloc},
	     %% corr. unless setrlimit() set
	     {system_total_memory, Total}];
	{unix, freebsd} ->
	    [{total_memory, Total}, {free_memory, Total-Alloc},
	     {system_total_memory, Total}];
	{unix, darwin} ->
	    [{total_memory, Total}, {free_memory, Total-Alloc},
	     {system_total_memory, Total}];
	_ -> % OSs using a port
	    dummy % not sent anyway
    end.

%%--Collect memory data, using port-------------------------------------

port_init() ->
    process_flag(trap_exit, true),
    Port = start_portprogram(),
    port_idle(Port).

start_portprogram() ->
    Command = filename:join([code:priv_dir(os_mon), "bin", "memsup"]),
    open_port({spawn, Command}, [{packet, 1}]).

%% The connected process loops are a bit awkward (several different
%% functions doing almost the same thing) as
%%   a) strategies for receiving regular memory data and extensive
%%      memory data are different
%%   b) memory collection can be cancelled, in which case the process
%%      should still wait for port response (which should come
%%      eventually!) but not receive any requests or cancellations
%%      meanwhile to prevent getting out of synch.
port_idle(Port) ->
    receive
	{Memsup, collect_sys} ->
	    Port ! {self(), {command, [?SHOW_MEM]}},
	    get_memory_usage(Port, undefined, Memsup);
	{Memsup, collect_ext_sys} ->
	    Port ! {self(), {command, [?SHOW_SYSTEM_MEM]}},
	    get_ext_memory_usage(Port, [], Memsup);
	cancel ->
	    %% Received after reply already has been delivered...
	    port_idle(Port);
	ext_cancel ->
	    %% Received after reply already has been delivered...
	    port_idle(Port);
	close ->
	    port_close(Port);
	{Port, {data, Data}} ->
	    exit({port_error, Data});
	{'EXIT', Port, Reason} ->
	    exit({port_died, Reason});
	{'EXIT', _Memsup, _Reason} ->
	    port_close(Port)
    end.

get_memory_usage(Port, Alloc, Memsup) ->
    receive
	{Port, {data, Data}} when Alloc==undefined ->
	    get_memory_usage(Port, erlang:list_to_integer(Data, 16), Memsup);
	{Port, {data, Data}} ->
	    Total = erlang:list_to_integer(Data, 16),
	    Memsup ! {collected_sys, {Alloc, Total}},
	    port_idle(Port);
	cancel ->
	    get_memory_usage_cancelled(Port, Alloc);
	close ->
	    port_close(Port);
	{'EXIT', Port, Reason} ->
	    exit({port_died, Reason});
	{'EXIT', _Memsup, _Reason} ->
	    port_close(Port)
    end.
get_memory_usage_cancelled(Port, Alloc) ->
    receive
	{Port, {data, _Data}} when Alloc==undefined ->
	    get_memory_usage_cancelled(Port, 0);
	{Port, {data, _Data}} ->
	    port_idle(Port);
	close ->
	    port_close(Port);
	{'EXIT', Port, Reason} ->
	    exit({port_died, Reason});
	{'EXIT', _Memsup, _Reason} ->
	    port_close(Port)
    end.

get_ext_memory_usage(Port, Accum, Memsup) ->
    Tab = [
	    {?MEM_SYSTEM_TOTAL,   system_total_memory},
	    {?MEM_TOTAL,          total_memory},
	    {?MEM_FREE,           free_memory},
	    {?MEM_BUFFERS,        buffered_memory},
	    {?MEM_CACHED,         cached_memory},
	    {?MEM_SHARED,         shared_memory},
	    {?MEM_LARGEST_FREE,   largest_free},
	    {?MEM_NUMBER_OF_FREE, number_of_free},
	    {?SWAP_TOTAL,	  total_swap},
	    {?SWAP_FREE,	  free_swap}
	],
    receive
	{Port, {data, [?SHOW_SYSTEM_MEM_END]}} ->
	    Memsup ! {collected_ext_sys, Accum},
	    port_idle(Port);
	{Port, {data, [Tag]}} ->
	    case lists:keysearch(Tag, 1, Tab) of
		{value, {Tag, ATag}} ->
		    get_ext_memory_usage(ATag, Port, Accum, Memsup);
		_ ->
		    exit({memsup_port_error, {Port,[Tag]}})
	    end;
	ext_cancel ->
	    get_ext_memory_usage_cancelled(Port);
	close ->
	    port_close(Port);
	{'EXIT', Port, Reason} ->
	    exit({port_died, Reason});
	{'EXIT', _Memsup, _Reason} ->
	    port_close(Port)
    end.
get_ext_memory_usage_cancelled(Port) ->
    Tab = [
	    {?MEM_SYSTEM_TOTAL,   system_total_memory},
	    {?MEM_TOTAL,          total_memory},
	    {?MEM_FREE,           free_memory},
	    {?MEM_BUFFERS,        buffered_memory},
	    {?MEM_CACHED,         cached_memory},
	    {?MEM_SHARED,         shared_memory},
	    {?MEM_LARGEST_FREE,   largest_free},
	    {?MEM_NUMBER_OF_FREE, number_of_free},
	    {?SWAP_TOTAL,	  total_swap},
	    {?SWAP_FREE,	  free_swap}
	],
    receive
	{Port, {data, [?SHOW_SYSTEM_MEM_END]}} ->
	    port_idle(Port);
	{Port, {data, [Tag]}} ->
	    case lists:keysearch(Tag, 1, Tab) of
		{value, {Tag, ATag}} ->
		    get_ext_memory_usage_cancelled(ATag, Port);
		_ ->
		    exit({memsup_port_error, {Port,[Tag]}})
	    end;
	close ->
	    port_close(Port);
	{'EXIT', Port, Reason} ->
	    exit({port_died, Reason});
	{'EXIT', _Memsup, _Reason} ->
	    port_close(Port)
    end.

get_ext_memory_usage(ATag, Port, Accum0, Memsup) ->
    receive
	{Port, {data, Data}} ->
	    Accum = [{ATag,erlang:list_to_integer(Data, 16)}|Accum0],
	    get_ext_memory_usage(Port, Accum, Memsup);
	cancel ->
	    get_ext_memory_usage_cancelled(ATag, Port);
	close ->
	    port_close(Port);
	{'EXIT', Port, Reason} ->
	    exit({port_died, Reason});
	{'EXIT', _Memsup, _Reason} ->
	    port_close(Port)
    end.
get_ext_memory_usage_cancelled(_ATag, Port) ->
    receive
	{Port, {data, _Data}} ->
	    get_ext_memory_usage_cancelled(Port);
	close ->
	    port_close(Port);
	{'EXIT', Port, Reason} ->
	    exit({port_died, Reason});
	{'EXIT', _Memsup, _Reason} ->
	    port_close(Port)
    end.

%%--Collect process data------------------------------------------------

  get_worst_memory_user ( ) - > { Pid , Bytes }
get_worst_memory_user()  ->
    get_worst_memory_user(processes(), self(), 0).

get_worst_memory_user([Pid|Pids], MaxPid, MaxMemBytes) ->
    case process_memory(Pid) of
	undefined ->
	    get_worst_memory_user(Pids, MaxPid, MaxMemBytes);
	MemoryBytes when MemoryBytes>MaxMemBytes ->
	    get_worst_memory_user(Pids, Pid, MemoryBytes);
	_MemoryBytes ->
	    get_worst_memory_user(Pids, MaxPid, MaxMemBytes)
    end;
get_worst_memory_user([], MaxPid, MaxMemBytes) ->
    {MaxPid, MaxMemBytes}.

process_memory(Pid) ->
    case process_info(Pid, memory) of
	{memory, Bytes} ->
	    Bytes;
  Pid must have died
	    undefined
    end.

 

set_alarm(AlarmId, AlarmDescr) ->
    case get(AlarmId) of
	set ->
	    ok;
	undefined ->
	    alarm_handler:set_alarm({AlarmId, AlarmDescr}),
	    put(AlarmId, set)
    end.

clear_alarm(AlarmId) ->
    case get(AlarmId) of
	set ->
	    alarm_handler:clear_alarm(AlarmId),
	    erase(AlarmId);
	_ ->
	    ok
    end.

clear_alarms() ->
    lists:foreach(fun({system_memory_high_watermark = Id, set}) ->
			  alarm_handler:clear_alarm(Id);
		     ({process_memory_high_watermark = Id, set}) ->
			  alarm_handler:clear_alarm(Id);
		     (_Other) ->
			  ignore
		  end,
		  get()).

%%--Auxiliary-----------------------------------------------------------

%% Type conversions
minutes_to_ms(Minutes) -> trunc(60000*Minutes).
sec_to_ms(Sec) -> trunc(1000*Sec).
ms_to_sec(MS) -> MS div 1000.

flush(Msg) ->
    receive
	{Msg, _} -> true;
	Msg -> true
    after 0 ->
	    true
    end.


 %CopyrightBegin%
 
 
 compliance with the License. You should have received a copy of the
 Erlang Public License along with this software. If not, it can be
 retrieved online at /.
 
 basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 the License for the specific language governing rights and limitations
 under the License.
 
 %CopyrightEnd%

 API
 for supervisor
 gen_server callbacks
 Other exports
 {OSfamily,OSname} | OSfamily
 bool()
 bool()  memsup_system_only
 int()   memory_check_interval, ms
 int()   memsup_helper_timeout, ms
 float() system_memory_high_watermark, %

 undefined | pid()
 undefined | TimerRef
 undefined | TimerRef
 [reg | {reg,From} | {ext,From}]
 [{ext,From}]
----------------------------------------------------------------------
 API
----------------------------------------------------------------------
 for backwards compatibility
----------------------------------------------------------------------
 gen_server callbacks
----------------------------------------------------------------------
 Linux supports this.
 Read the values of some configuration parameters
 Initiate first data collection
 Return result of latest memory check
 Special case: get_memory_data called before any memory data
 has been collected
 When using a port, the extensive memory collection is slightly
 When not using a port, the regular memory collection is used
 for extensive memory data as well
 It's time to check memory
 Memory data collected
 also flush any reg_collection_timeout message)
 Check if system alarm should be set/cleared
 Check if process data should be collected
 Check if process alarm should be set/cleared
 Then send a reply to all waiting clients, in preserved time order
 Last, if this was a periodic check, start a timer for the next
 one. New timeout = interval-time spent collecting,
 Issue a warning message
 Send a dummy reply to all waiting clients, preserving time order
 If it is a periodic check which has timed out, start a timer for
 New timeout = interval-helper timeout
 Extensive memory data collected (port_mode==true only)
 also flush any ext_collection_timeout message)
 Send the reply to all waiting clients, preserving time order
 also flush any collected_ext_sys message)
 Issue a warning message
 Send a dummy reply to all waiting clients, preserving time order
 Error in data collecting (port connected or temporary) process
 os_mon-2.0.1
 For live downgrade to/upgrade from os_mon-1.8[.1] and -2.0
 Downgrade from this version
 Kill the helper process, if there is one,
 and flush messages from it
 Cancel timers, flush timeout messages
 and send dummy replies to any pending clients
 Downgrade to old state record
 wd_timer
 pending
 ext_wd_timer
 ext_pending
 Upgrade to this version
 Old state record
 Flush memsup_helper messages
 Cancel timers, flush timeout messages
 and send dummy replies to any pending clients
 Upgrade to this state record
 Restart the port process (it must use new memsup code)
----------------------------------------------------------------------
 Other exports
----------------------------------------------------------------------
----------------------------------------------------------------------
----------------------------------------------------------------------
-- Fetching kernel bit support ---------------------------------------
--Replying to pending clients-----------------------------------------
--Collect memory data, no port----------------------------------------
 get_memory_usage(OS) -> {Alloc, Total}
 Uses vm_stat command. This appears to lie about the page size in
 FreeBSD: Look in /usr/include/sys/vmmeter.h for the format of struct
 vmmeter
 Win32: Find out how much memory is in use by asking
 the os_mon_sysinfo process.
 corr. unless setrlimit() set
 OSs using a port
 not sent anyway
--Collect memory data, using port-------------------------------------
 The connected process loops are a bit awkward (several different
 functions doing almost the same thing) as
   a) strategies for receiving regular memory data and extensive
      memory data are different
   b) memory collection can be cancelled, in which case the process
      should still wait for port response (which should come
      eventually!) but not receive any requests or cancellations
      meanwhile to prevent getting out of synch.
 Received after reply already has been delivered...
 Received after reply already has been delivered...
--Collect process data------------------------------------------------
--Auxiliary-----------------------------------------------------------
 Type conversions
  Copyright Ericsson AB 1996 - 2009 . All Rights Reserved .
  The contents of this file are subject to the Erlang Public License ,
  Version 1.1 , ( the " License " ) ; you may not use this file except in
  Software distributed under the License is distributed on an " AS IS "
-module(memsup).
-behaviour(gen_server).

-export([get_memory_data/0, get_system_memory_data/0,
	 get_check_interval/0, set_check_interval/1,
	 get_procmem_high_watermark/0, set_procmem_high_watermark/1,
	 get_sysmem_high_watermark/0, set_sysmem_high_watermark/1,
	 get_helper_timeout/0, set_helper_timeout/1,
	 get_os_wordsize/0]).
-export([dummy_reply/1, param_type/2, param_default/1]).

-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
	 terminate/2, code_change/3]).

-export([format_status/2]).

-include("memsup.hrl").

-record(state,

  undefined | { Alloc , Total }
  undefined | { Pid , Alloc }


	}).


start_link() ->
    gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).

get_os_wordsize() ->
    os_mon:call(memsup, get_os_wordsize, infinity).

get_memory_data() ->
    os_mon:call(memsup, get_memory_data, infinity).

get_system_memory_data() ->
    os_mon:call(memsup, get_system_memory_data, infinity).

get_check_interval() ->
    os_mon:call(memsup, get_check_interval, infinity).
set_check_interval(Minutes) ->
    case param_type(memory_check_interval, Minutes) of
	true ->
	    os_mon:call(memsup, {set_check_interval, MS}, infinity);
	false ->
	    erlang:error(badarg)
    end.

get_procmem_high_watermark() ->
    os_mon:call(memsup, get_procmem_high_watermark, infinity).
set_procmem_high_watermark(Float) ->
    case param_type(process_memory_high_watermark, Float) of
	true ->
	    os_mon:call(memsup, {set_procmem_high_watermark, Float},
			infinity);
	false ->
	    erlang:error(badarg)
    end.

get_sysmem_high_watermark() ->
    os_mon:call(memsup, get_sysmem_high_watermark, infinity).
set_sysmem_high_watermark(Float) ->
    case param_type(system_memory_high_watermark, Float) of
	true ->
	    os_mon:call(memsup, {set_sysmem_high_watermark, Float},
			infinity);
	false ->
	    erlang:error(badarg)
    end.

get_helper_timeout() ->
    os_mon:call(memsup, get_helper_timeout, infinity).
set_helper_timeout(Seconds) ->
    case param_type(memsup_helper_timeout, Seconds) of
	true ->
	    os_mon:call(memsup, {set_helper_timeout, Seconds});
	false ->
	    erlang:error(badarg)
    end.

dummy_reply(get_memory_data) ->
    dummy_reply(get_memory_data,
		os_mon:get_env(memsup, memsup_system_only));
dummy_reply(get_system_memory_data) ->
    [];
dummy_reply(get_os_wordsize) ->
    0;
dummy_reply(get_check_interval) ->
    minutes_to_ms(os_mon:get_env(memsup, memory_check_interval));
dummy_reply({set_check_interval, _}) ->
    ok;
dummy_reply(get_procmem_high_watermark) ->
    trunc(100 * os_mon:get_env(memsup, process_memory_high_watermark));
dummy_reply({set_procmem_high_watermark, _}) ->
    ok;
dummy_reply(get_sysmem_high_watermark) ->
    trunc(100 * os_mon:get_env(memsup, system_memory_high_watermark));
dummy_reply({set_sysmem_high_watermark, _}) ->
    ok;
dummy_reply(get_helper_timeout) ->
    os_mon:get_env(memsup, memsup_helper_timeout);
dummy_reply({set_helper_timeout, _}) ->
    ok.
dummy_reply(get_memory_data, true) ->
    {0,0,undefined};
dummy_reply(get_memory_data, false) ->
    {0,0,{self(),0}}.

param_type(memsup_system_only, Val) when Val==true; Val==false -> true;
param_type(memory_check_interval, Val) when is_integer(Val),
                                            Val>0 -> true;
param_type(memsup_helper_timeout, Val) when is_integer(Val),
                                            Val>0 -> true;
param_type(system_memory_high_watermark, Val) when is_number(Val),
						   0=<Val,
						   Val=<1 -> true;
param_type(process_memory_high_watermark, Val) when is_number(Val),
						    0=<Val,
						    Val=<1 -> true;
param_type(_Param, _Val) -> false.

param_default(memsup_system_only) -> false;
param_default(memory_check_interval) -> 1;
param_default(memsup_helper_timeout) -> 30;
param_default(system_memory_high_watermark) -> 0.80;
param_default(process_memory_high_watermark) -> 0.05.


init([]) ->
    process_flag(trap_exit, true),
    process_flag(priority, low),

    OS = os:type(),
    PortMode = case OS of
		   {unix, darwin} -> false;
		   {unix, freebsd} -> false;
		   {unix, linux} -> true;
		   {unix, openbsd} -> true;
		   {unix, irix64} -> true;
		   {unix, irix} -> true;
		   {unix, sunos} -> true;
		   {win32, _OSname} -> false;
		   vxworks -> true;
		   _ ->
		       exit({unsupported_os, OS})
	       end,
    Pid = if
	      PortMode ->
		  spawn_link(fun() -> port_init() end);
	      not PortMode ->
		  undefined
	  end,

    SysOnly = os_mon:get_env(memsup, memsup_system_only),
    Timeout = os_mon:get_env(memsup, memory_check_interval),
    HelperTimeout = os_mon:get_env(memsup, memsup_helper_timeout),
    SysMem = os_mon:get_env(memsup, system_memory_high_watermark),
    ProcMem = os_mon:get_env(memsup, process_memory_high_watermark),

    self() ! time_to_collect,

    {ok, #state{os=OS, port_mode=PortMode,

		sys_only           = SysOnly,
		timeout            = minutes_to_ms(Timeout),
		helper_timeout     = sec_to_ms(HelperTimeout),
		sys_mem_watermark  = SysMem,
		proc_mem_watermark = ProcMem,

		pid=Pid}}.

handle_call(get_os_wordsize, _From, State) ->
    Wordsize = get_os_wordsize(State#state.os),
    {reply, Wordsize, State};
handle_call(get_memory_data, From, State) ->
    case State#state.mem_usage of
	{Alloc, Total} ->
	    Worst = State#state.worst_mem_user,
	    {reply, {Total, Alloc, Worst}, State};
	
	undefined ->
	    case State#state.wd_timer of
		undefined ->
		    WDTimer = erlang:send_after(State#state.timeout,
						self(),
						reg_collection_timeout),
		    Pending = [{reg,From}],
		    if
			State#state.port_mode ->
			    State#state.pid ! {self(), collect_sys},
			    {noreply, State#state{wd_timer=WDTimer,
						  pending=Pending}};
			true ->
			    OS = State#state.os,
			    Self = self(),
			    Pid = spawn_link(fun() ->
						     MU = get_memory_usage(OS),
						     Self ! {collected_sys,MU}
					     end),
			    {noreply, State#state{pid=Pid,
						  wd_timer=WDTimer,
						  pending=Pending}}
		    end;
		_TimerRef ->
		    Pending = [{reg,From} | State#state.pending],
		    {noreply, State#state{pending=Pending}}
	    end
    end;

handle_call(get_system_memory_data,From,#state{port_mode=true}=State) ->
  different than a regular one
    case State#state.ext_wd_timer of
	undefined ->
	    WDTimer = erlang:send_after(State#state.helper_timeout,
					self(),
					ext_collection_timeout),
	    State#state.pid ! {self(), collect_ext_sys},
	    {noreply, State#state{ext_wd_timer=WDTimer,
				  ext_pending=[{ext,From}]}};
	_TimerRef ->
	    Pending = [{ext,From} | State#state.ext_pending],
	    {noreply, State#state{ext_pending=Pending}}
    end;
handle_call(get_system_memory_data, From, State) ->
    case State#state.wd_timer of
	undefined ->
	    WDTimer = erlang:send_after(State#state.helper_timeout,
					self(),
					reg_collection_timeout),
	    OS = State#state.os,
	    Self = self(),
	    Pid = spawn_link(fun() ->
				     MemUsage = get_memory_usage(OS),
				     Self ! {collected_sys, MemUsage}
			     end),
	    {noreply, State#state{pid=Pid, wd_timer=WDTimer,
				  pending=[{ext,From}]}};
	_TimerRef ->
	    Pending = [{ext,From} | State#state.pending],
	    {noreply, State#state{pending=Pending}}
    end;

handle_call(get_check_interval, _From, State) ->
    {reply, State#state.timeout, State};
handle_call({set_check_interval, MS}, _From, State) ->
    {reply, ok, State#state{timeout=MS}};

handle_call(get_procmem_high_watermark, _From, State) ->
    {reply, trunc(100 * State#state.proc_mem_watermark), State};
handle_call({set_procmem_high_watermark, Float}, _From, State) ->
    {reply, ok, State#state{proc_mem_watermark=Float}};

handle_call(get_sysmem_high_watermark, _From, State) ->
    {reply, trunc(100 * State#state.sys_mem_watermark), State};
handle_call({set_sysmem_high_watermark, Float}, _From, State) ->
    {reply, ok, State#state{sys_mem_watermark=Float}};

handle_call(get_helper_timeout, _From, State) ->
    {reply, ms_to_sec(State#state.helper_timeout), State};
handle_call({set_helper_timeout, Seconds}, _From, State) ->
    {reply, ok, State#state{helper_timeout=sec_to_ms(Seconds)}};

  The following are only for test purposes ( whitebox testing ) .
handle_call({set_sys_hw, HW}, _From, State) ->
    {reply, ok, State#state{sys_mem_watermark=HW}};
handle_call({set_pid_hw, HW}, _From, State) ->
    {reply, ok, State#state{proc_mem_watermark=HW}};
handle_call(get_state, _From, State) ->
    {reply, State, State}.

handle_cast(_Msg, State) ->
    {noreply, State}.

handle_info(time_to_collect, State) ->
    case State#state.wd_timer of
	undefined ->
	    WDTimer = erlang:send_after(State#state.helper_timeout,
					self(),
					reg_collection_timeout),
	    if
		State#state.port_mode ->
		    State#state.pid ! {self(), collect_sys},
		    {noreply, State#state{wd_timer=WDTimer,
					  pending=[reg]}};
		true ->
		    OS = State#state.os,
		    Self = self(),
		    Pid = spawn_link(fun() ->
					     MU = get_memory_usage(OS),
					     Self ! {collected_sys,MU}
				     end),
		    {noreply, State#state{pid=Pid, wd_timer=WDTimer,
					  pending=[reg]}}
	    end;
	_TimerRef ->
	    {noreply, State#state{pending=[reg|State#state.pending]}}
    end;

handle_info({collected_sys, {Alloc,Total}}, State) ->

  Cancel watchdog timer ( and as a security measure ,
    TimeSpent = case erlang:cancel_timer(State#state.wd_timer) of
		    false ->
			State#state.helper_timeout;
		    TimeLeft ->
			State#state.helper_timeout-TimeLeft
		end,
    flush(reg_collection_timeout),

  First check if this is the result of a periodic memory check
  and update alarms and State if this is the case
    State2 =
	case lists:member(reg, State#state.pending) of
	    true ->

		if
		    Alloc > State#state.sys_mem_watermark*Total ->
			set_alarm(system_memory_high_watermark, []);
		    true ->
			clear_alarm(system_memory_high_watermark)
		end,

		case State#state.sys_only of
		    false ->
			{Pid, Bytes} = get_worst_memory_user(),
			Threshold= State#state.proc_mem_watermark*Total,

			if
			    Bytes > Threshold ->
				set_alarm(process_memory_high_watermark,
					  Pid);
			    true ->
				clear_alarm(process_memory_high_watermark)
			end,
			
			State#state{mem_usage={Alloc, Total},
				    worst_mem_user={Pid, Bytes}};
		    true ->
			State#state{mem_usage={Alloc, Total}}
		end;
	    false ->
		State
	end,

    Worst = State2#state.worst_mem_user,
    SysMemUsage = get_ext_memory_usage(State2#state.os, {Alloc,Total}),
    reply(State2#state.pending, {Total,Alloc,Worst}, SysMemUsage),

    case lists:member(reg, State#state.pending) of
	true ->
	    Time = case State2#state.timeout - TimeSpent of
		       MS when MS<0 ->
			   0;
		       MS ->
			   MS
		   end,
	    erlang:send_after(Time, self(), time_to_collect);
	false ->
	    ignore
    end,
    {noreply, State2#state{wd_timer=undefined, pending=[]}};
handle_info({'EXIT', Pid, normal}, State) when is_pid(Pid) ->
  Temporary pid terminating when job is done
    {noreply, State};

  Timeout during data collection
handle_info(reg_collection_timeout, State) ->

  Cancel memory collection ( and as a security measure ,
  also flush any collected_sys message )
    if
	State#state.port_mode -> State#state.pid ! cancel;
	true -> exit(State#state.pid, cancel)
    end,
    flush(collected_sys),

    Str = "OS_MON (memsup) timeout, no data collected~n",
    error_logger:warning_msg(Str),

    reply(State#state.pending,
	  dummy_reply(get_memory_data, State#state.sys_only),
	  dummy_reply(get_system_memory_data)),

  the next one
    case lists:member(reg, State#state.pending) of
	true ->
	    Time =
		case State#state.timeout-State#state.helper_timeout of
		    MS when MS<0 -> 0;
		    MS -> MS
		end,
	    erlang:send_after(Time, self(), time_to_collect);
	false ->
	    ignore
    end,
    {noreply, State#state{wd_timer=undefined, pending=[]}};
handle_info({'EXIT', Pid, cancel}, State) when is_pid(Pid) ->
  Temporary pid terminating as ordered
    {noreply, State};

handle_info({collected_ext_sys, SysMemUsage}, State) ->

  Cancel watchdog timer ( and as a security mearure ,
    erlang:cancel_timer(State#state.ext_wd_timer),
    flush(ext_collection_timeout),

    reply(State#state.ext_pending, undef, SysMemUsage),

    {noreply, State#state{ext_wd_timer=undefined, ext_pending=[]}};

  Timeout during ext memory data collection ( port_mode==true only )
handle_info(ext_collection_timeout, State) ->

  Cancel memory collection ( and as a security measure ,
    State#state.pid ! ext_cancel,
    flush(collected_ext_sys),

    Str = "OS_MON (memsup) timeout, no data collected~n",
    error_logger:warning_msg(Str),

    SysMemUsage = dummy_reply(get_system_memory_data),
    reply(State#state.ext_pending, undef, SysMemUsage),

    {noreply, State#state{ext_wd_timer=undefined, ext_pending=[]}};

handle_info({'EXIT', Pid, Reason}, State) when is_pid(Pid) ->
    {stop, Reason, State};
	    
handle_info(_Info, State) ->
    {noreply, State}.

terminate(_Reason, State) ->
    if
	State#state.port_mode -> State#state.pid ! close;
	true -> ok
    end,
    clear_alarms(),
    ok.

code_change(Vsn, PrevState, "1.8") ->
    case Vsn of

	{down, _Vsn} ->

	    case PrevState#state.pid of
		Pid when is_pid(Pid) ->
  to prevent ' EXIT ' message
		    exit(Pid, cancel);
		undefined -> ignore
	    end,
	    flush(collected_sys),
	    flush(collected_ext_sys),

	    case PrevState#state.wd_timer of
		undefined ->
		    ignore;
		TimerRef1 ->
		    erlang:cancel_timer(TimerRef1),
		    SysOnly = PrevState#state.sys_only,
		    MemUsage = dummy_reply(get_memory_data, SysOnly),
		    SysMemUsage1 = dummy_reply(get_system_memory_data),
		    reply(PrevState#state.pending,MemUsage,SysMemUsage1)
	    end,
	    case PrevState#state.ext_wd_timer of
		undefined ->
		    ignore;
		TimerRef2 ->
		    erlang:cancel_timer(TimerRef2),
		    SysMemUsage2 = dummy_reply(get_system_memory_data),
		    reply(PrevState#state.pending, undef, SysMemUsage2)
	    end,
	    flush(reg_collection_timeout),
	    flush(ext_collection_timeout),

	    State = {state,
		     PrevState#state.timeout,
		     PrevState#state.mem_usage,
		     PrevState#state.worst_mem_user,
		     PrevState#state.sys_mem_watermark,
		     PrevState#state.proc_mem_watermark,
  collect_procmem
		     PrevState#state.helper_timeout},
	    {ok, State};

	_Vsn ->

	    {state,
	     Timeout, MemUsage, WorstMemUser,
	     SysMemWatermark, ProcMemWatermark, CollProc,
	     WDTimer, Pending, ExtWDTimer, ExtPending,
	     HelperTimeout} = PrevState,
	    SysOnly = not CollProc,

	    flush(collected_sys),
	    flush(collected_proc),
	    flush(collected_ext_sys),
		     
	    case WDTimer of
		undefined ->
		    ignore;
		TimerRef1 ->
		    erlang:cancel_timer(TimerRef1),
		    MemUsage = dummy_reply(get_memory_data, SysOnly),
		    Pending2 = lists:map(fun(From) -> {reg,From} end,
					 Pending),
		    reply(Pending2, MemUsage, undef)
	    end,
	    case ExtWDTimer of
		undefined ->
		    ignore;
		TimerRef2 ->
		    erlang:cancel_timer(TimerRef2),
		    SysMemUsage = dummy_reply(get_system_memory_data),
		    ExtPending2 = lists:map(fun(From) -> {ext,From} end,
					    ExtPending),
		    reply(ExtPending2, undef, SysMemUsage)
	    end,
	    flush(reg_collection_timeout),
	    flush(ext_collection_timeout),

	    OS = os:type(),
	    PortMode = case OS of
			   {unix, darwin} -> false;
			   {unix, freebsd} -> false;
			   {unix, linux} -> false;
			   {unix, openbsd} -> true;
			   {unix, sunos} -> true;
			   {win32, _OSname} -> false;
			   vxworks -> true
		       end,
	    Pid = if
		      PortMode -> spawn_link(fun() -> port_init() end);
		      not PortMode -> undefined
		  end,

	    State = #state{os = OS,
			   port_mode = PortMode,
			   mem_usage = MemUsage,
			   worst_mem_user = WorstMemUser,
			   sys_only  = SysOnly,
			   timeout         = Timeout,
			   helper_timeout  = HelperTimeout,
			   sys_mem_watermark = SysMemWatermark,
			   proc_mem_watermark = ProcMemWatermark,
			   pid                = Pid,
			   wd_timer           = undefined,
			   ext_wd_timer       = undefined,
			   pending            = [],
			   ext_pending        = []},
	    {ok, State}
    end;
code_change(_Vsn, State, "2.0") ->

    Pid = case State#state.port_mode of
	      true ->
		  State#state.pid ! close,
		  spawn_link(fun() -> port_init() end);
	      false ->
		  State#state.pid
	  end,
    {ok, State#state{pid=Pid}};
	  
code_change(_OldVsn, State, _Extra) ->
    {ok, State}.


format_status(_Opt, [_PDict, #state{timeout=Timeout, mem_usage=MemUsage,
				    worst_mem_user=WorstMemUser}]) ->
    {Allocated, Total} = MemUsage,
    WorstMemFormat = case WorstMemUser of
			 {Pid, Mem} ->
			     [{"Pid", Pid}, {"Memory", Mem}];
			 undefined ->
			     undefined
		     end,
    [{data, [{"Timeout", Timeout}]},
     {items, {"Memory Usage", [{"Allocated", Allocated},
			       {"Total", Total}]}},
     {items, {"Worst Memory User", WorstMemFormat}}].


  Internal functions


get_os_wordsize({unix, sunos}) ->
    String = clean_string(os:cmd("isainfo -b")),
    erlang:list_to_integer(String);
get_os_wordsize({unix, irix64})  -> 64;
get_os_wordsize({unix, irix})    -> 32;
get_os_wordsize({unix, linux})   -> get_os_wordsize_with_uname();
get_os_wordsize({unix, darwin})  -> get_os_wordsize_with_uname();
get_os_wordsize({unix, netbsd})  -> get_os_wordsize_with_uname();
get_os_wordsize({unix, freebsd}) -> get_os_wordsize_with_uname();
get_os_wordsize({unix, openbsd}) -> get_os_wordsize_with_uname();
get_os_wordsize(_)               -> unsupported_os.

get_os_wordsize_with_uname() ->
    String = clean_string(os:cmd("uname -m")),
    case String of
	"x86_64"  -> 64;
	"sparc64" -> 64;
	_         -> 32
    end.

clean_string(String) -> lists:flatten(string:tokens(String,"\r\n\t ")).
    


reply(Pending, MemUsage, SysMemUsage) ->
    lists:foreach(fun(reg) ->
			  ignore;
		     ({reg, From}) ->
			  gen_server:reply(From, MemUsage);
		     ({ext, From}) ->
			  gen_server:reply(From, SysMemUsage)
		  end,
		  lists:reverse(Pending)).



   :
  Mac OS X 10.2.2 - the pages given are based on 4000 bytes , but
  the vm_stat command tells us that it is 4096 ...
get_memory_usage({unix,darwin}) ->
    Str = os:cmd("/usr/bin/vm_stat"),
    {ok, [Free],Str2} = io_lib:fread("Pages free:~d.",skip_to_eol(Str)),
    {ok, [Active],Str3} =
	io_lib:fread("Pages active:~d.", skip_to_eol(Str2)),
    {ok, [Inactive],Str4} =
	io_lib:fread("Pages inactive:~d.", skip_to_eol(Str3)),
    {ok, [Wired],_} =
	io_lib:fread("Pages wired down:~d.", skip_to_eol(Str4)),
    NMemUsed  = (Wired + Active + Inactive) * 4000,
    NMemTotal = NMemUsed + Free * 4000,
    {NMemUsed,NMemTotal};

get_memory_usage({unix,freebsd}) ->
    PageSize  = freebsd_sysctl("vm.stats.vm.v_page_size"),
    PageCount = freebsd_sysctl("vm.stats.vm.v_page_count"),
    FreeCount = freebsd_sysctl("vm.stats.vm.v_free_count"),
    NMemUsed  = (PageCount - FreeCount) * PageSize,
    NMemTotal = PageCount * PageSize,
    {NMemUsed, NMemTotal};

get_memory_usage({win32,_OSname}) ->
    [Result|_] = os_mon_sysinfo:get_mem_info(),
    {ok, [_MemLoad, TotPhys, AvailPhys,
	  _TotPage, _AvailPage, _TotV, _AvailV], _RestStr} =
	io_lib:fread("~d~d~d~d~d~d~d", Result),
    {TotPhys-AvailPhys, TotPhys}.

skip_to_eol([]) ->
    [];
skip_to_eol([$\n | T]) ->
    T;
skip_to_eol([_ | T]) ->
    skip_to_eol(T).

freebsd_sysctl(Def) ->
    list_to_integer(os:cmd("/sbin/sysctl -n " ++ Def) -- "\n").

  get_ext_memory_usage(OS , { Alloc , Total } ) - > [ { Tag , Bytes } ]
get_ext_memory_usage(OS, {Alloc, Total}) ->
    case OS of
	{win32, _} ->
	    [{total_memory, Total}, {free_memory, Total-Alloc},
	     {system_total_memory, Total}];
	{unix, linux} ->
	    [{total_memory, Total}, {free_memory, Total-Alloc},
	     {system_total_memory, Total}];
	{unix, freebsd} ->
	    [{total_memory, Total}, {free_memory, Total-Alloc},
	     {system_total_memory, Total}];
	{unix, darwin} ->
	    [{total_memory, Total}, {free_memory, Total-Alloc},
	     {system_total_memory, Total}];
    end.


port_init() ->
    process_flag(trap_exit, true),
    Port = start_portprogram(),
    port_idle(Port).

start_portprogram() ->
    Command = filename:join([code:priv_dir(os_mon), "bin", "memsup"]),
    open_port({spawn, Command}, [{packet, 1}]).

port_idle(Port) ->
    receive
	{Memsup, collect_sys} ->
	    Port ! {self(), {command, [?SHOW_MEM]}},
	    get_memory_usage(Port, undefined, Memsup);
	{Memsup, collect_ext_sys} ->
	    Port ! {self(), {command, [?SHOW_SYSTEM_MEM]}},
	    get_ext_memory_usage(Port, [], Memsup);
	cancel ->
	    port_idle(Port);
	ext_cancel ->
	    port_idle(Port);
	close ->
	    port_close(Port);
	{Port, {data, Data}} ->
	    exit({port_error, Data});
	{'EXIT', Port, Reason} ->
	    exit({port_died, Reason});
	{'EXIT', _Memsup, _Reason} ->
	    port_close(Port)
    end.

get_memory_usage(Port, Alloc, Memsup) ->
    receive
	{Port, {data, Data}} when Alloc==undefined ->
	    get_memory_usage(Port, erlang:list_to_integer(Data, 16), Memsup);
	{Port, {data, Data}} ->
	    Total = erlang:list_to_integer(Data, 16),
	    Memsup ! {collected_sys, {Alloc, Total}},
	    port_idle(Port);
	cancel ->
	    get_memory_usage_cancelled(Port, Alloc);
	close ->
	    port_close(Port);
	{'EXIT', Port, Reason} ->
	    exit({port_died, Reason});
	{'EXIT', _Memsup, _Reason} ->
	    port_close(Port)
    end.
get_memory_usage_cancelled(Port, Alloc) ->
    receive
	{Port, {data, _Data}} when Alloc==undefined ->
	    get_memory_usage_cancelled(Port, 0);
	{Port, {data, _Data}} ->
	    port_idle(Port);
	close ->
	    port_close(Port);
	{'EXIT', Port, Reason} ->
	    exit({port_died, Reason});
	{'EXIT', _Memsup, _Reason} ->
	    port_close(Port)
    end.

get_ext_memory_usage(Port, Accum, Memsup) ->
    Tab = [
	    {?MEM_SYSTEM_TOTAL,   system_total_memory},
	    {?MEM_TOTAL,          total_memory},
	    {?MEM_FREE,           free_memory},
	    {?MEM_BUFFERS,        buffered_memory},
	    {?MEM_CACHED,         cached_memory},
	    {?MEM_SHARED,         shared_memory},
	    {?MEM_LARGEST_FREE,   largest_free},
	    {?MEM_NUMBER_OF_FREE, number_of_free},
	    {?SWAP_TOTAL,	  total_swap},
	    {?SWAP_FREE,	  free_swap}
	],
    receive
	{Port, {data, [?SHOW_SYSTEM_MEM_END]}} ->
	    Memsup ! {collected_ext_sys, Accum},
	    port_idle(Port);
	{Port, {data, [Tag]}} ->
	    case lists:keysearch(Tag, 1, Tab) of
		{value, {Tag, ATag}} ->
		    get_ext_memory_usage(ATag, Port, Accum, Memsup);
		_ ->
		    exit({memsup_port_error, {Port,[Tag]}})
	    end;
	ext_cancel ->
	    get_ext_memory_usage_cancelled(Port);
	close ->
	    port_close(Port);
	{'EXIT', Port, Reason} ->
	    exit({port_died, Reason});
	{'EXIT', _Memsup, _Reason} ->
	    port_close(Port)
    end.
get_ext_memory_usage_cancelled(Port) ->
    Tab = [
	    {?MEM_SYSTEM_TOTAL,   system_total_memory},
	    {?MEM_TOTAL,          total_memory},
	    {?MEM_FREE,           free_memory},
	    {?MEM_BUFFERS,        buffered_memory},
	    {?MEM_CACHED,         cached_memory},
	    {?MEM_SHARED,         shared_memory},
	    {?MEM_LARGEST_FREE,   largest_free},
	    {?MEM_NUMBER_OF_FREE, number_of_free},
	    {?SWAP_TOTAL,	  total_swap},
	    {?SWAP_FREE,	  free_swap}
	],
    receive
	{Port, {data, [?SHOW_SYSTEM_MEM_END]}} ->
	    port_idle(Port);
	{Port, {data, [Tag]}} ->
	    case lists:keysearch(Tag, 1, Tab) of
		{value, {Tag, ATag}} ->
		    get_ext_memory_usage_cancelled(ATag, Port);
		_ ->
		    exit({memsup_port_error, {Port,[Tag]}})
	    end;
	close ->
	    port_close(Port);
	{'EXIT', Port, Reason} ->
	    exit({port_died, Reason});
	{'EXIT', _Memsup, _Reason} ->
	    port_close(Port)
    end.

get_ext_memory_usage(ATag, Port, Accum0, Memsup) ->
    receive
	{Port, {data, Data}} ->
	    Accum = [{ATag,erlang:list_to_integer(Data, 16)}|Accum0],
	    get_ext_memory_usage(Port, Accum, Memsup);
	cancel ->
	    get_ext_memory_usage_cancelled(ATag, Port);
	close ->
	    port_close(Port);
	{'EXIT', Port, Reason} ->
	    exit({port_died, Reason});
	{'EXIT', _Memsup, _Reason} ->
	    port_close(Port)
    end.
get_ext_memory_usage_cancelled(_ATag, Port) ->
    receive
	{Port, {data, _Data}} ->
	    get_ext_memory_usage_cancelled(Port);
	close ->
	    port_close(Port);
	{'EXIT', Port, Reason} ->
	    exit({port_died, Reason});
	{'EXIT', _Memsup, _Reason} ->
	    port_close(Port)
    end.


  get_worst_memory_user ( ) - > { Pid , Bytes }
get_worst_memory_user()  ->
    get_worst_memory_user(processes(), self(), 0).

get_worst_memory_user([Pid|Pids], MaxPid, MaxMemBytes) ->
    case process_memory(Pid) of
	undefined ->
	    get_worst_memory_user(Pids, MaxPid, MaxMemBytes);
	MemoryBytes when MemoryBytes>MaxMemBytes ->
	    get_worst_memory_user(Pids, Pid, MemoryBytes);
	_MemoryBytes ->
	    get_worst_memory_user(Pids, MaxPid, MaxMemBytes)
    end;
get_worst_memory_user([], MaxPid, MaxMemBytes) ->
    {MaxPid, MaxMemBytes}.

process_memory(Pid) ->
    case process_info(Pid, memory) of
	{memory, Bytes} ->
	    Bytes;
  Pid must have died
	    undefined
    end.

 

set_alarm(AlarmId, AlarmDescr) ->
    case get(AlarmId) of
	set ->
	    ok;
	undefined ->
	    alarm_handler:set_alarm({AlarmId, AlarmDescr}),
	    put(AlarmId, set)
    end.

clear_alarm(AlarmId) ->
    case get(AlarmId) of
	set ->
	    alarm_handler:clear_alarm(AlarmId),
	    erase(AlarmId);
	_ ->
	    ok
    end.

clear_alarms() ->
    lists:foreach(fun({system_memory_high_watermark = Id, set}) ->
			  alarm_handler:clear_alarm(Id);
		     ({process_memory_high_watermark = Id, set}) ->
			  alarm_handler:clear_alarm(Id);
		     (_Other) ->
			  ignore
		  end,
		  get()).


minutes_to_ms(Minutes) -> trunc(60000*Minutes).
sec_to_ms(Sec) -> trunc(1000*Sec).
ms_to_sec(MS) -> MS div 1000.

flush(Msg) ->
    receive
	{Msg, _} -> true;
	Msg -> true
    after 0 ->
	    true
    end.
