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Comparing AnyEvent-SNMP/SNMP.pm (file contents):
Revision 1.2 by root, Fri Apr 10 06:50:16 2009 UTC vs.
Revision 1.3 by root, Sat Apr 18 10:17:53 2009 UTC

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43This module does not export anything and does not require you to do 43This module does not export anything and does not require you to do
44anything special apart from loading it I<before doing any non-blocking 44anything special apart from loading it I<before doing any non-blocking
45requests with Net::SNMP>. It is recommended but not required to load this 45requests with Net::SNMP>. It is recommended but not required to load this
46module before C<Net::SNMP>. 46module before C<Net::SNMP>.
47 47
48=head1 GLOBAL VARIABLES
49
50=over 4
51
52=item $AnyEvent::SNMP::MAX_OUTSTANDING (default: C<50>, dynamic)
53
54Use this package variable to restrict the number of outstanding SNMP
55requests at any point in time.
56
57Net::SNMP is very fast at creating and sending SNMP requests, but much
58slower at parsing (big, bulk) responses. This makes it easy to request a
59lot of data that can take many seconds to parse.
60
61In the best case, this can lead to unnecessary delays (and even time-outs,
62as the data has been received but not yet processed) and in the worst
63case, this can lead to packet loss, when the receive queue overflows and
64the kernel can no longer accept new packets.
65
66To avoid this, you can (and should) limit the number of outstanding requests
67to a number low enough so that parsing time doesn't introduce noticable delays.
68
69Unfortunately, this number depends not only on processing speed and load
70of the machine running Net::SNMP, but also on the network latency and the
71speed of your SNMP agents.
72
73AnyEvent::SNMP tries to dynamically adjust this number dynamically upwards
74and downwards.
75
76Note that you can use L<Net::SNMP::XS> to speed up parsing of responses
77considerably.
78
79=item $AnyEvent::SNMP::MIN_RECVQUEUE (default: C<4>)
80
81=item $AnyEvent::SNMP::MAX_RECVQUEUE (default: C<64>)
82
83These values specify the minimum and maximum receive queue length (in
84units of one response packet).
85
86When AnyEvent::SNMP handles $MAX_RECVQUEUE or more packets per iteration
87it will reduce $MAX_OUTSTANDING. If it handles less than $MIN_RECVQUEUE,
88it increases $MAX_OUTSTANDING.
89
90This has the result of adjusting the number of outstanding requests so that
91the recv queue is between the minimum and maximu, usually.
92
93This algorithm works reasonably well as long as the responses, response
94latencies and processing times are the same size per packet on average.
95
96=back
97
98=head1 COMPATIBILITY
99
100This module may be used as a drop in replacement for the
101Net::SNMP::Dispatcher in existing programs. You can still call
102C<snmp_dispatcher> to start the event-loop, but then you loose the benefit
103of mixing Net::SNMP events with other events.
104
105 use AnyEvent::SNMP;
106 use Net::SNMP;
107
108 # just use Net::SNMP as before
109
110 # ... start non-blocking snmp request(s)...
111 Net::SNMP->session (
112 -hostname => "127.0.0.1",
113 -community => "public",
114 -nonblocking => 1,
115 )->get_request (-callback => sub { ... });
116
117 snmp_dispatcher;
118
48=cut 119=cut
49 120
50package AnyEvent::SNMP; 121package AnyEvent::SNMP;
51 122
52no warnings; 123no warnings;
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61} 132}
62 133
63use Net::SNMP (); 134use Net::SNMP ();
64use AnyEvent (); 135use AnyEvent ();
65 136
66our $VERSION = '0.11'; 137our $VERSION = '0.2';
67 138
68$Net::SNMP::DISPATCHER = instance Net::SNMP::Dispatcher; 139$Net::SNMP::DISPATCHER = instance Net::SNMP::Dispatcher;
69 140
70our $MESSAGE_PROCESSING = $Net::SNMP::Dispatcher::MESSAGE_PROCESSING; 141our $MESSAGE_PROCESSING = $Net::SNMP::Dispatcher::MESSAGE_PROCESSING;
71 142
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73my $timer = sub { shift->timer (@_) }; 144my $timer = sub { shift->timer (@_) };
74AnyEvent::post_detect { $timer = AnyEvent->can ("timer") }; 145AnyEvent::post_detect { $timer = AnyEvent->can ("timer") };
75 146
76our $BUSY; 147our $BUSY;
77our %TRANSPORT; # address => [count, watcher] 148our %TRANSPORT; # address => [count, watcher]
149our @QUEUE;
150our $MAX_OUTSTANDING = 50;
151our $MIN_RECVQUEUE = 4;
152our $MAX_RECVQUEUE = 64;
153
154sub kick_job;
78 155
79sub _send_pdu { 156sub _send_pdu {
80 my ($pdu, $retries) = @_; 157 my ($pdu, $retries) = @_;
81 158
82 # mostly copied from Net::SNMP::Dispatch 159 # mostly copied from Net::SNMP::Dispatch
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85 # create the new outgoing message. 162 # create the new outgoing message.
86 my $msg = $MESSAGE_PROCESSING->prepare_outgoing_msg ($pdu); 163 my $msg = $MESSAGE_PROCESSING->prepare_outgoing_msg ($pdu);
87 164
88 if (!defined $msg) { 165 if (!defined $msg) {
89 --$BUSY; 166 --$BUSY;
167 kick_job;
90 # Inform the command generator about the Message Processing error. 168 # Inform the command generator about the Message Processing error.
91 $pdu->status_information ($MESSAGE_PROCESSING->error); 169 $pdu->status_information ($MESSAGE_PROCESSING->error);
92 return; 170 return;
93 } 171 }
94 172
… …
103 undef $retry_w; 181 undef $retry_w;
104 _send_pdu ($pdu, $retries); 182 _send_pdu ($pdu, $retries);
105 }); 183 });
106 } else { 184 } else {
107 --$BUSY; 185 --$BUSY;
186 kick_job;
108 } 187 }
109 188
110 # Inform the command generator about the send() error. 189 # Inform the command generator about the send() error.
111 $pdu->status_information ($msg->error); 190 $pdu->status_information ($msg->error);
112 return; 191 return;
… …
117 my $transport = $msg->transport; 196 my $transport = $msg->transport;
118 197
119 # register the transport 198 # register the transport
120 unless ($TRANSPORT{$transport+0}[0]++) { 199 unless ($TRANSPORT{$transport+0}[0]++) {
121 $TRANSPORT{$transport+0}[1] = AnyEvent->io (fh => $transport->socket, poll => 'r', cb => sub { 200 $TRANSPORT{$transport+0}[1] = AnyEvent->io (fh => $transport->socket, poll => 'r', cb => sub {
201 for my $count (1..$MAX_RECVQUEUE) { # handle up to this many requests in one go
122 # Create a new Message object to receive the response 202 # Create a new Message object to receive the response
123 my ($msg, $error) = Net::SNMP::Message->new (-transport => $transport); 203 my ($msg, $error) = Net::SNMP::Message->new (-transport => $transport);
124 204
125 if (!defined $msg) { 205 if (!defined $msg) {
126 die sprintf 'Failed to create Message object [%s]', $error; 206 die sprintf 'Failed to create Message object [%s]', $error;
207 }
208
209 # Read the message from the Transport Layer
210 if (!defined $msg->recv) {
211 if ($transport->connectionless) {
212 if ($count < $MIN_RECVQUEUE && @QUEUE) {
213 ++$MAX_OUTSTANDING;
214 kick_job;
215 }
216 } else {
217 # for some reason, connected-oriented transports seem to need this
218 delete $TRANSPORT{$transport+0}
219 unless --$TRANSPORT{$transport+0}[0];
220 }
221
222 $msg->error;
223 return;
224 }
225
226 # For connection-oriented Transport Domains, it is possible to
227 # "recv" an empty buffer if reassembly is required.
228 if (!$msg->length) {
229 return;
230 }
231
232 # Hand the message over to Message Processing.
233 if (!defined $MESSAGE_PROCESSING->prepare_data_elements ($msg)) {
234 $MESSAGE_PROCESSING->error;
235 return;
236 }
237
238 # Set the error if applicable.
239 $msg->error ($MESSAGE_PROCESSING->error) if $MESSAGE_PROCESSING->error;
240
241 # Notify the command generator to process the response.
242 $msg->process_response_pdu;
243
244 # Cancel the timeout.
245 my $rtimeout_w = $msg->timeout_id;
246 if ($$rtimeout_w) {
247 undef $$rtimeout_w;
248
249 --$BUSY;
250 kick_job;
251
252 unless (--$TRANSPORT{$transport+0}[0]) {
253 delete $TRANSPORT{$transport+0};
254 return;
255 }
256 }
127 } 257 }
128 258
129 # Read the message from the Transport Layer 259 $MAX_OUTSTANDING = (int $MAX_OUTSTANDING * 0.9) || 1;
130 if (!defined $msg->recv) {
131 # for some reason, connected-oriented transports seem to need this
132 unless ($transport->connectionless) {
133 delete $TRANSPORT{$transport+0}
134 unless --$TRANSPORT{$transport+0}[0];
135 }
136
137 $msg->error;
138 return;
139 }
140
141 # For connection-oriented Transport Domains, it is possible to
142 # "recv" an empty buffer if reassembly is required.
143 if (!$msg->length) {
144 return;
145 }
146
147 # Hand the message over to Message Processing.
148 if (!defined $MESSAGE_PROCESSING->prepare_data_elements ($msg)) {
149 $MESSAGE_PROCESSING->error;
150 return;
151 }
152
153 # Set the error if applicable.
154 $msg->error ($MESSAGE_PROCESSING->error) if $MESSAGE_PROCESSING->error;
155
156 # Cancel the timeout.
157 my $rtimeout_w = $msg->timeout_id;
158 if ($$rtimeout_w) {
159 undef $$rtimeout_w;
160 delete $TRANSPORT{$transport+0}
161 unless --$TRANSPORT{$transport+0}[0];
162
163 --$BUSY;
164 }
165
166 # Notify the command generator to process the response.
167 $msg->process_response_pdu;
168 }); 260 });
169 } 261 }
170 262
171 #####d# timeout_id, wtf?
172 $msg->timeout_id (\(my $rtimeout_w = 263 $msg->timeout_id (\(my $rtimeout_w =
173 AnyEvent->$timer (after => $pdu->timeout, cb => sub { 264 AnyEvent->$timer (after => $pdu->timeout, cb => sub {
174 my $rtimeout_w = $msg->timeout_id; 265 my $rtimeout_w = $msg->timeout_id;
175 if ($$rtimeout_w) { 266 if ($$rtimeout_w) {
176 undef $$rtimeout_w; 267 undef $$rtimeout_w;
… …
179 } 270 }
180 271
181 if ($retries--) { 272 if ($retries--) {
182 _send_pdu ($pdu, $retries); 273 _send_pdu ($pdu, $retries);
183 } else { 274 } else {
184 --$BUSY;
185 $MESSAGE_PROCESSING->msg_handle_delete ($pdu->msg_id); 275 $MESSAGE_PROCESSING->msg_handle_delete ($pdu->msg_id);
186 $pdu->status_information ("No response from remote host '%s'", $pdu->hostname); 276 $pdu->status_information ("No response from remote host '%s'", $pdu->hostname);
277
278 --$BUSY;
279 kick_job;
187 } 280 }
188 }) 281 })
189 )); 282 ));
190 } else { 283 } else {
191 --$BUSY; 284 --$BUSY;
285 kick_job;
192 } 286 }
193} 287}
194 288
289sub kick_job {
290 while ($BUSY < $MAX_OUTSTANDING) {
291 my $pdu = shift @QUEUE
292 or last;
293
294 ++$BUSY;
295
296 _send_pdu $pdu, $pdu->retries;
297 }
298}
195sub send_pdu($$$) { 299sub send_pdu($$$) {
196 my (undef, $pdu, $delay) = @_; 300 my (undef, $pdu, $delay) = @_;
197 301
198 ++$BUSY; 302 # $delay is not very sensibly implemented by AnyEvent::SNMP,
199 303 # but apparently it is not a very sensible feature.
200 if ($delay > 0) { 304 if ($delay > 0) {
305 ++$BUSY;
201 my $delay_w; $delay_w = AnyEvent->$timer (after => $delay, cb => sub { 306 my $delay_w; $delay_w = AnyEvent->$timer (after => $delay, cb => sub {
202 undef $delay_w; 307 undef $delay_w;
203 _send_pdu ($pdu, $pdu->retries); 308 --$BUSY;
309 push @QUEUE, $pdu;
310 kick_job;
204 }); 311 });
205 return 1; 312 return 1;
206 } 313 }
207 314
208 _send_pdu $pdu, $pdu->retries; 315 push @QUEUE, $pdu;
316 kick_job;
317
209 1 318 1
210} 319}
211 320
212sub activate($) { 321sub activate($) {
213 AnyEvent->one_event while $BUSY; 322 AnyEvent->one_event while $BUSY;
214} 323}
215 324
216sub one_event($) { 325sub one_event($) {
217 die; 326 AnyEvent->one_event;
218} 327}
219 328
220=head1 SEE ALSO 329=head1 SEE ALSO
221 330
222L<AnyEvent>, L<Net::SNMP>, L<Net::SNMP::EV>. 331L<AnyEvent>, L<Net::SNMP>, L<Net::SNMP::XS>, L<Net::SNMP::EV>.
223 332
224=head1 AUTHOR 333=head1 AUTHOR
225 334
226 Marc Lehmann <schmorp@schmorp.de> 335 Marc Lehmann <schmorp@schmorp.de>
227 http://home.schmorp.de/ 336 http://home.schmorp.de/

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