1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
|
% Licensed under the Apache License, Version 2.0 (the "License"); you may not
% use this file except in compliance with the License. You may obtain a copy of
% the License at
%
% http://www.apache.org/licenses/LICENSE-2.0
%
% Unless required by applicable law or agreed to in writing, software
% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
% License for the specific language governing permissions and limitations under
% the License.
-module(couch_os_process).
-behaviour(gen_server).
-export([start_link/1, start_link/2, start_link/3, stop/1]).
-export([set_timeout/2, prompt/2, prompt_many/2]).
-export([send/2, writeline/2, readline/1, writejson/2, readjson/1]).
-export([init/1, terminate/2, handle_call/3, handle_cast/2, handle_info/2, code_change/3]).
-include("couch_db.hrl").
-define(PORT_OPTIONS, [stream, {line, 4096}, binary, exit_status, hide]).
-record(os_proc,
{command,
port,
writer,
reader,
timeout=5000
}).
start_link(Command) ->
start_link(Command, []).
start_link(Command, Options) ->
start_link(Command, Options, ?PORT_OPTIONS).
start_link(Command, Options, PortOptions) ->
gen_server:start_link(couch_os_process, [Command, Options, PortOptions], []).
stop(Pid) ->
gen_server:cast(Pid, stop).
% Read/Write API
set_timeout(Pid, TimeOut) when is_integer(TimeOut) ->
ok = gen_server:call(Pid, {set_timeout, TimeOut}, infinity).
% Used by couch_db_update_notifier.erl
send(Pid, Data) ->
gen_server:cast(Pid, {send, Data}).
prompt(Pid, Data) ->
case gen_server:call(Pid, {prompt, Data}, infinity) of
{ok, Result} ->
Result;
Error ->
?LOG_ERROR("OS Process Error ~p :: ~p",[Pid,Error]),
throw(Error)
end.
prompt_many(Pid, DataList) ->
OsProc = gen_server:call(Pid, get_os_proc, infinity),
true = port_connect(OsProc#os_proc.port, self()),
try
send_many(OsProc, DataList),
receive_many(length(DataList), OsProc, [])
after
% Can throw badarg error, when OsProc Pid is dead or port was closed
% by the readline function on error/timeout.
(catch port_connect(OsProc#os_proc.port, Pid)),
unlink(OsProc#os_proc.port),
drop_port_messages(OsProc#os_proc.port)
end.
send_many(_OsProc, []) ->
ok;
send_many(#os_proc{writer = Writer} = OsProc, [Data | Rest]) ->
Writer(OsProc, Data),
send_many(OsProc, Rest).
receive_many(0, _OsProc, Acc) ->
{ok, lists:reverse(Acc)};
receive_many(N, #os_proc{reader = Reader} = OsProc, Acc) ->
Line = Reader(OsProc),
receive_many(N - 1, OsProc, [Line | Acc]).
drop_port_messages(Port) ->
receive
{Port, _} ->
drop_port_messages(Port)
after 0 ->
ok
end.
% Utility functions for reading and writing
% in custom functions
writeline(OsProc, Data) when is_record(OsProc, os_proc) ->
port_command(OsProc#os_proc.port, [Data, $\n]).
readline(#os_proc{} = OsProc) ->
readline(OsProc, []).
readline(#os_proc{port = Port} = OsProc, Acc) ->
receive
{Port, {data, {noeol, Data}}} when is_binary(Acc) ->
readline(OsProc, <<Acc/binary,Data/binary>>);
{Port, {data, {noeol, Data}}} when is_binary(Data) ->
readline(OsProc, Data);
{Port, {data, {noeol, Data}}} ->
readline(OsProc, [Data|Acc]);
{Port, {data, {eol, <<Data/binary>>}}} when is_binary(Acc) ->
[<<Acc/binary,Data/binary>>];
{Port, {data, {eol, Data}}} when is_binary(Data) ->
[Data];
{Port, {data, {eol, Data}}} ->
lists:reverse(Acc, Data);
{Port, Err} ->
catch port_close(Port),
throw({os_process_error, Err})
after OsProc#os_proc.timeout ->
catch port_close(Port),
throw({os_process_error, "OS process timed out."})
end.
% Standard JSON functions
writejson(OsProc, Data) when is_record(OsProc, os_proc) ->
JsonData = ?JSON_ENCODE(Data),
?LOG_DEBUG("OS Process ~p Input :: ~s", [OsProc#os_proc.port, JsonData]),
true = writeline(OsProc, JsonData).
readjson(OsProc) when is_record(OsProc, os_proc) ->
Line = iolist_to_binary(readline(OsProc)),
?LOG_DEBUG("OS Process ~p Output :: ~s", [OsProc#os_proc.port, Line]),
try
% Don't actually parse the whole JSON. Just try to see if it's
% a command or a doc map/reduce/filter/show/list/update output.
% If it's a command then parse the whole JSON and execute the
% command, otherwise return the raw JSON line to the caller.
pick_command(Line)
catch
throw:abort ->
{json, Line};
throw:{cmd, _Cmd} ->
case ?JSON_DECODE(Line) of
[<<"log">>, Msg] when is_binary(Msg) ->
% we got a message to log. Log it and continue
?LOG_INFO("OS Process ~p Log :: ~s", [OsProc#os_proc.port, Msg]),
readjson(OsProc);
[<<"error">>, Id, Reason] ->
throw({error, {couch_util:to_existing_atom(Id),Reason}});
[<<"fatal">>, Id, Reason] ->
?LOG_INFO("OS Process ~p Fatal Error :: ~s ~p",
[OsProc#os_proc.port, Id, Reason]),
throw({couch_util:to_existing_atom(Id),Reason});
_Result ->
{json, Line}
end
end.
pick_command(Line) ->
json_stream_parse:events(Line, fun pick_command0/1).
pick_command0(array_start) ->
fun pick_command1/1;
pick_command0(_) ->
throw(abort).
pick_command1(<<"log">> = Cmd) ->
throw({cmd, Cmd});
pick_command1(<<"error">> = Cmd) ->
throw({cmd, Cmd});
pick_command1(<<"fatal">> = Cmd) ->
throw({cmd, Cmd});
pick_command1(_) ->
throw(abort).
% gen_server API
init([Command, Options, PortOptions]) ->
PrivDir = couch_util:priv_dir(),
Spawnkiller = filename:join(PrivDir, "couchspawnkillable"),
BaseProc = #os_proc{
command=Command,
port=open_port({spawn, Spawnkiller ++ " " ++ Command}, PortOptions),
writer=fun writejson/2,
reader=fun readjson/1
},
KillCmd = iolist_to_binary(readline(BaseProc)),
Pid = self(),
?LOG_DEBUG("OS Process Start :: ~p", [BaseProc#os_proc.port]),
spawn(fun() ->
% this ensure the real os process is killed when this process dies.
erlang:monitor(process, Pid),
receive _ -> ok end,
os:cmd(?b2l(iolist_to_binary(KillCmd)))
end),
OsProc =
lists:foldl(fun(Opt, Proc) ->
case Opt of
{writer, Writer} when is_function(Writer) ->
Proc#os_proc{writer=Writer};
{reader, Reader} when is_function(Reader) ->
Proc#os_proc{reader=Reader};
{timeout, TimeOut} when is_integer(TimeOut) ->
Proc#os_proc{timeout=TimeOut}
end
end, BaseProc, Options),
{ok, OsProc}.
terminate(_Reason, #os_proc{port=Port}) ->
catch port_close(Port),
ok.
handle_call(get_os_proc, _From, OsProc) ->
{reply, OsProc, OsProc};
handle_call({set_timeout, TimeOut}, _From, OsProc) ->
{reply, ok, OsProc#os_proc{timeout=TimeOut}};
handle_call({prompt, Data}, _From, OsProc) ->
#os_proc{writer=Writer, reader=Reader} = OsProc,
try
Writer(OsProc, Data),
{reply, {ok, Reader(OsProc)}, OsProc}
catch
throw:{error, OsError} ->
{reply, OsError, OsProc};
throw:OtherError ->
{stop, normal, OtherError, OsProc}
end.
handle_cast({send, Data}, #os_proc{writer=Writer}=OsProc) ->
try
Writer(OsProc, Data),
{noreply, OsProc}
catch
throw:OsError ->
?LOG_ERROR("Failed sending data: ~p -> ~p", [Data, OsError]),
{stop, normal, OsProc}
end;
handle_cast(stop, OsProc) ->
{stop, normal, OsProc};
handle_cast(Msg, OsProc) ->
?LOG_DEBUG("OS Proc: Unknown cast: ~p", [Msg]),
{noreply, OsProc}.
handle_info({Port, {exit_status, 0}}, #os_proc{port=Port}=OsProc) ->
?LOG_INFO("OS Process terminated normally", []),
{stop, normal, OsProc};
handle_info({Port, {exit_status, Status}}, #os_proc{port=Port}=OsProc) ->
?LOG_ERROR("OS Process died with status: ~p", [Status]),
{stop, {exit_status, Status}, OsProc}.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
|
