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43 | This module does not export anything and does not require you to do |
43 | This module does not export anything and does not require you to do |
44 | anything special apart from loading it I<before doing any non-blocking |
44 | anything special apart from loading it I<before doing any non-blocking |
45 | requests with Net::SNMP>. It is recommended but not required to load this |
45 | requests with Net::SNMP>. It is recommended but not required to load this |
46 | module before C<Net::SNMP>. |
46 | module before C<Net::SNMP>. |
47 | |
47 | |
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48 | =head1 GLOBAL VARIABLES |
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49 | |
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50 | =over 4 |
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51 | |
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52 | =item $AnyEvent::SNMP::MAX_OUTSTANDING (default: C<50>, dynamic) |
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53 | |
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54 | Use this package variable to restrict the number of outstanding SNMP |
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55 | requests at any point in time. |
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56 | |
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57 | Net::SNMP is very fast at creating and sending SNMP requests, but much |
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58 | slower at parsing (big, bulk) responses. This makes it easy to request a |
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59 | lot of data that can take many seconds to parse. |
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60 | |
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61 | In the best case, this can lead to unnecessary delays (and even time-outs, |
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62 | as the data has been received but not yet processed) and in the worst |
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63 | case, this can lead to packet loss, when the receive queue overflows and |
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64 | the kernel can no longer accept new packets. |
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65 | |
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66 | To avoid this, you can (and should) limit the number of outstanding requests |
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67 | to a number low enough so that parsing time doesn't introduce noticable delays. |
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68 | |
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69 | Unfortunately, this number depends not only on processing speed and load |
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70 | of the machine running Net::SNMP, but also on the network latency and the |
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71 | speed of your SNMP agents. |
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72 | |
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73 | AnyEvent::SNMP tries to dynamically adjust this number dynamically upwards |
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74 | and downwards. |
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75 | |
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76 | Note that you can use L<Net::SNMP::XS> to speed up parsing of responses |
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77 | considerably. |
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78 | |
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79 | =item $AnyEvent::SNMP::MIN_RECVQUEUE (default: C<4>) |
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80 | |
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81 | =item $AnyEvent::SNMP::MAX_RECVQUEUE (default: C<64>) |
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82 | |
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83 | These values specify the minimum and maximum receive queue length (in |
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84 | units of one response packet). |
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85 | |
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86 | When AnyEvent::SNMP handles $MAX_RECVQUEUE or more packets per iteration |
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87 | it will reduce $MAX_OUTSTANDING. If it handles less than $MIN_RECVQUEUE, |
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88 | it increases $MAX_OUTSTANDING. |
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89 | |
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90 | This has the result of adjusting the number of outstanding requests so that |
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91 | the recv queue is between the minimum and maximu, usually. |
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92 | |
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93 | This algorithm works reasonably well as long as the responses, response |
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94 | latencies and processing times are the same size per packet on average. |
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95 | |
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96 | =back |
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97 | |
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98 | =head1 COMPATIBILITY |
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99 | |
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100 | This module may be used as a drop in replacement for the |
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101 | Net::SNMP::Dispatcher in existing programs. You can still call |
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102 | C<snmp_dispatcher> to start the event-loop, but then you loose the benefit |
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103 | of mixing Net::SNMP events with other events. |
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104 | |
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105 | use AnyEvent::SNMP; |
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106 | use Net::SNMP; |
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107 | |
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108 | # just use Net::SNMP as before |
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109 | |
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110 | # ... start non-blocking snmp request(s)... |
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111 | Net::SNMP->session ( |
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112 | -hostname => "127.0.0.1", |
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113 | -community => "public", |
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114 | -nonblocking => 1, |
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115 | )->get_request (-callback => sub { ... }); |
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116 | |
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117 | snmp_dispatcher; |
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118 | |
48 | =cut |
119 | =cut |
49 | |
120 | |
50 | package AnyEvent::SNMP; |
121 | package AnyEvent::SNMP; |
51 | |
122 | |
52 | no warnings; |
123 | no warnings; |
… | |
… | |
61 | } |
132 | } |
62 | |
133 | |
63 | use Net::SNMP (); |
134 | use Net::SNMP (); |
64 | use AnyEvent (); |
135 | use AnyEvent (); |
65 | |
136 | |
66 | our $VERSION = '0.1'; |
137 | our $VERSION = '0.2'; |
67 | |
138 | |
68 | $Net::SNMP::DISPATCHER = instance Net::SNMP::Dispatcher; |
139 | $Net::SNMP::DISPATCHER = instance Net::SNMP::Dispatcher; |
69 | |
140 | |
70 | our $MESSAGE_PROCESSING = $Net::SNMP::Dispatcher::MESSAGE_PROCESSING; |
141 | our $MESSAGE_PROCESSING = $Net::SNMP::Dispatcher::MESSAGE_PROCESSING; |
71 | |
142 | |
… | |
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73 | my $timer = sub { shift->timer (@_) }; |
144 | my $timer = sub { shift->timer (@_) }; |
74 | AnyEvent::post_detect { $timer = AnyEvent->can ("timer") }; |
145 | AnyEvent::post_detect { $timer = AnyEvent->can ("timer") }; |
75 | |
146 | |
76 | our $BUSY; |
147 | our $BUSY; |
77 | our %TRANSPORT; # address => [count, watcher] |
148 | our %TRANSPORT; # address => [count, watcher] |
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149 | our @QUEUE; |
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150 | our $MAX_OUTSTANDING = 50; |
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151 | our $MIN_RECVQUEUE = 4; |
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152 | our $MAX_RECVQUEUE = 64; |
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153 | |
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154 | sub kick_job; |
78 | |
155 | |
79 | sub _send_pdu { |
156 | sub _send_pdu { |
80 | my ($pdu, $retries) = @_; |
157 | my ($pdu, $retries) = @_; |
81 | |
158 | |
82 | # mostly copied from Net::SNMP::Dispatch |
159 | # mostly copied from Net::SNMP::Dispatch |
… | |
… | |
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; |
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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 | |
… | |
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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; |
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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; |
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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 { |
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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; |
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207 | } |
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208 | |
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209 | # Read the message from the Transport Layer |
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210 | if (!defined $msg->recv) { |
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211 | if ($transport->connectionless) { |
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212 | # if we handled very few replies and we have queued work, try |
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213 | # to increase the parallelity as we probably can handle more. |
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214 | if ($count < $MIN_RECVQUEUE && @QUEUE) { |
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215 | ++$MAX_OUTSTANDING; |
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216 | kick_job; |
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217 | } |
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218 | } else { |
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219 | # for some reason, connected-oriented transports seem to need this |
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220 | delete $TRANSPORT{$transport+0} |
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221 | unless --$TRANSPORT{$transport+0}[0]; |
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222 | } |
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223 | |
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224 | $msg->error; |
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225 | return; |
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226 | } |
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227 | |
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228 | # For connection-oriented Transport Domains, it is possible to |
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229 | # "recv" an empty buffer if reassembly is required. |
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230 | if (!$msg->length) { |
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231 | return; |
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232 | } |
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233 | |
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234 | # Hand the message over to Message Processing. |
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235 | if (!defined $MESSAGE_PROCESSING->prepare_data_elements ($msg)) { |
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236 | $MESSAGE_PROCESSING->error; |
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237 | return; |
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238 | } |
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239 | |
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240 | # Set the error if applicable. |
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241 | $msg->error ($MESSAGE_PROCESSING->error) if $MESSAGE_PROCESSING->error; |
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242 | |
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243 | # Notify the command generator to process the response. |
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244 | $msg->process_response_pdu; |
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245 | |
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246 | # Cancel the timeout. |
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247 | my $rtimeout_w = $msg->timeout_id; |
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248 | if ($$rtimeout_w) { |
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249 | undef $$rtimeout_w; |
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250 | |
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251 | --$BUSY; |
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252 | kick_job; |
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253 | |
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254 | unless (--$TRANSPORT{$transport+0}[0]) { |
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255 | delete $TRANSPORT{$transport+0}; |
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256 | return; |
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257 | } |
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258 | } |
127 | } |
259 | } |
128 | |
260 | |
129 | # Read the message from the Transport Layer |
261 | # when we end up here, we successfully handled $MAX_RECVQUEUE |
130 | if (!defined $msg->recv) { |
262 | # replies in one iteration, so assume we are overloaded |
131 | # for some reason, connected-oriented transports seem to need this |
263 | # and reduce the amount of parallelity. |
132 | unless ($transport->connectionless) { |
264 | $MAX_OUTSTANDING = (int $MAX_OUTSTANDING * 0.9) || 1; |
133 | delete $TRANSPORT{$transport+0} |
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134 | unless --$TRANSPORT{$transport+0}[0]; |
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135 | } |
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136 | |
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137 | $msg->error; |
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138 | return; |
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139 | } |
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140 | |
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141 | # For connection-oriented Transport Domains, it is possible to |
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142 | # "recv" an empty buffer if reassembly is required. |
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143 | if (!$msg->length) { |
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144 | return; |
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145 | } |
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146 | |
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147 | # Hand the message over to Message Processing. |
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148 | if (!defined $MESSAGE_PROCESSING->prepare_data_elements ($msg)) { |
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149 | $MESSAGE_PROCESSING->error; |
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150 | return; |
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151 | } |
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152 | |
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153 | # Set the error if applicable. |
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154 | $msg->error ($MESSAGE_PROCESSING->error) if $MESSAGE_PROCESSING->error; |
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155 | |
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156 | # Cancel the timeout. |
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157 | my $rtimeout_w = $msg->timeout_id; |
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158 | if ($$rtimeout_w) { |
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159 | undef $$rtimeout_w; |
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160 | delete $TRANSPORT{$transport+0} |
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161 | unless --$TRANSPORT{$transport+0}[0]; |
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162 | |
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163 | --$BUSY; |
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164 | } |
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165 | |
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166 | # Notify the command generator to process the response. |
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167 | $msg->process_response_pdu; |
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168 | }); |
265 | }); |
169 | } |
266 | } |
170 | |
267 | |
171 | #####d# timeout_id, wtf? |
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172 | $msg->timeout_id (\(my $rtimeout_w = |
268 | $msg->timeout_id (\(my $rtimeout_w = |
173 | AnyEvent->$timer (after => $pdu->timeout, cb => sub { |
269 | AnyEvent->$timer (after => $pdu->timeout, cb => sub { |
174 | my $rtimeout_w = $msg->timeout_id; |
270 | my $rtimeout_w = $msg->timeout_id; |
175 | if ($$rtimeout_w) { |
271 | if ($$rtimeout_w) { |
176 | undef $$rtimeout_w; |
272 | undef $$rtimeout_w; |
… | |
… | |
179 | } |
275 | } |
180 | |
276 | |
181 | if ($retries--) { |
277 | if ($retries--) { |
182 | _send_pdu ($pdu, $retries); |
278 | _send_pdu ($pdu, $retries); |
183 | } else { |
279 | } else { |
184 | --$BUSY; |
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185 | $MESSAGE_PROCESSING->msg_handle_delete ($pdu->msg_id); |
280 | $MESSAGE_PROCESSING->msg_handle_delete ($pdu->msg_id); |
186 | $pdu->status_information ("No response from remote host '%s'", $pdu->hostname); |
281 | $pdu->status_information ("No response from remote host '%s'", $pdu->hostname); |
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282 | |
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283 | --$BUSY; |
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284 | kick_job; |
187 | } |
285 | } |
188 | }) |
286 | }) |
189 | )); |
287 | )); |
190 | } else { |
288 | } else { |
191 | --$BUSY; |
289 | --$BUSY; |
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290 | kick_job; |
192 | } |
291 | } |
193 | } |
292 | } |
194 | |
293 | |
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294 | sub kick_job { |
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295 | while ($BUSY < $MAX_OUTSTANDING) { |
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296 | my $pdu = shift @QUEUE |
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297 | or last; |
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298 | |
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299 | ++$BUSY; |
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300 | |
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301 | _send_pdu $pdu, $pdu->retries; |
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302 | } |
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303 | } |
195 | sub send_pdu($$$) { |
304 | sub send_pdu($$$) { |
196 | my (undef, $pdu, $delay) = @_; |
305 | my (undef, $pdu, $delay) = @_; |
197 | |
306 | |
198 | ++$BUSY; |
307 | # $delay is not very sensibly implemented by AnyEvent::SNMP, |
199 | |
308 | # but apparently it is not a very sensible feature. |
200 | if ($delay > 0) { |
309 | if ($delay > 0) { |
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310 | ++$BUSY; |
201 | my $delay_w; $delay_w = AnyEvent->$timer (after => $delay, cb => sub { |
311 | my $delay_w; $delay_w = AnyEvent->$timer (after => $delay, cb => sub { |
202 | undef $delay_w; |
312 | undef $delay_w; |
203 | _send_pdu ($pdu, $pdu->retries); |
313 | --$BUSY; |
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314 | push @QUEUE, $pdu; |
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315 | kick_job; |
204 | }); |
316 | }); |
205 | return 1; |
317 | return 1; |
206 | } |
318 | } |
207 | |
319 | |
208 | _send_pdu $pdu, $pdu->retries; |
320 | push @QUEUE, $pdu; |
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321 | kick_job; |
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322 | |
209 | 1 |
323 | 1 |
210 | } |
324 | } |
211 | |
325 | |
212 | sub activate($) { |
326 | sub activate($) { |
213 | AnyEvent->one_event while $BUSY; |
327 | AnyEvent->one_event while $BUSY; |
214 | } |
328 | } |
215 | |
329 | |
216 | sub one_event($) { |
330 | sub one_event($) { |
217 | die; |
331 | AnyEvent->one_event; |
218 | } |
332 | } |
219 | |
333 | |
220 | =head1 SEE ALSO |
334 | =head1 SEE ALSO |
221 | |
335 | |
222 | L<AnyEvent>, L<Net::SNMP>, L<Net::SNMP::EV>. |
336 | L<AnyEvent>, L<Net::SNMP>, L<Net::SNMP::XS>, L<Net::SNMP::EV>. |
223 | |
337 | |
224 | =head1 AUTHOR |
338 | =head1 AUTHOR |
225 | |
339 | |
226 | Marc Lehmann <schmorp@schmorp.de> |
340 | Marc Lehmann <schmorp@schmorp.de> |
227 | http://home.schmorp.de/ |
341 | http://home.schmorp.de/ |