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
|
% 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, write/2, read/1, prompt/2, async/3]).
-export([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, 1024}, binary, exit_status, hide]).
-record(os_proc,
{command,
port,
writer,
reader,
timeout
}).
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}).
write(Pid, Data) ->
gen_server:call(Pid, {write, Data}).
read(Pid) ->
gen_server:call(Pid, read).
prompt(Pid, Data) ->
gen_server:call(Pid, {prompt, Data}).
async(Pid, Data, CallBack) ->
gen_server:cast(Pid, {async, Data, CallBack}).
% 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(OsProc) when is_record(OsProc, os_proc) ->
readline(OsProc, []).
readline(OsProc, Acc) when is_record(OsProc, os_proc) ->
#os_proc{port=Port} = OsProc,
receive
{Port, {data, {noeol, Data}}} ->
readline(OsProc, [Data|Acc]);
{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) ->
true = writeline(OsProc, ?JSON_ENCODE(Data)).
readjson(OsProc) when is_record(OsProc, os_proc) ->
Line = readline(OsProc),
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 Log Message: ~s", [Msg]),
readjson(OsProc);
{[{<<"error">>, Id}, {<<"reason">>, Reason}]} ->
throw({list_to_atom(binary_to_list(Id)),Reason});
{[{<<"reason">>, Reason}, {<<"error">>, Id}]} ->
throw({list_to_atom(binary_to_list(Id)),Reason});
Result ->
Result
end.
% gen_server API
init([Command, Options, PortOptions]) ->
BaseProc = #os_proc{
command=Command,
port=open_port({spawn, Command}, PortOptions),
writer=fun writejson/2,
reader=fun readjson/1,
timeout=5000
},
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=nil}) ->
ok;
terminate(_Reason, #os_proc{port=Port}) ->
catch port_close(Port),
ok.
handle_call({set_timeout, TimeOut}, _From, OsProc) ->
{reply, ok, OsProc#os_proc{timeout=TimeOut}};
handle_call({write, Data}, _From, OsProc) ->
Writer = OsProc#os_proc.writer,
{reply, Writer(OsProc, Data), OsProc};
handle_call(read, _From, OsProc) ->
Reader = OsProc#os_proc.reader,
{reply, Reader(OsProc), OsProc};
handle_call({prompt, Data}, _From, OsProc) ->
#os_proc{writer=Writer, reader=Reader} = OsProc,
Writer(OsProc, Data),
{reply, Reader(OsProc), OsProc}.
handle_cast({async, Data, CallBack}, OsProc) ->
#os_proc{writer=Writer, reader=Reader} = OsProc,
Writer(OsProc, Data),
CallBack(Reader(OsProc)),
{noreply, OsProc};
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, Status}}, #os_proc{port=Port}=OsProc) ->
?LOG_ERROR("OS Process died with status: ~p", [Status]),
{stop, error, OsProc};
handle_info(Msg, OsProc) ->
?LOG_DEBUG("OS Proc: Unknown info: ~p", [Msg]),
{noreply, OsProc}.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
|
