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| 124 | =back |
124 | =back |
| 125 | |
125 | |
| 126 | For libev, you would typically use an C<ev_async> watcher: the |
126 | For libev, you would typically use an C<ev_async> watcher: the |
| 127 | C<want_poll> callback would invoke C<ev_async_send> to wake up the event |
127 | C<want_poll> callback would invoke C<ev_async_send> to wake up the event |
| 128 | loop. Inside the callback set for the watcher, one would call C<eio_poll |
128 | loop. Inside the callback set for the watcher, one would call C<eio_poll |
| 129 | ()> (followed by C<ev_async_send> again if C<eio_poll> indicates that not |
129 | ()>. |
| 130 | all requests have been handled yet). The race is taken care of because |
130 | |
| 131 | libev resets/rearms the async watcher before calling your callback, |
131 | If C<eio_poll ()> is configured to not handle all results in one go |
| 132 | and therefore, before calling C<eio_poll>. This might result in (some) |
132 | (i.e. it returns C<-1>) then you should start an idle watcher that calls |
| 133 | spurious wake-ups, but is generally harmless. |
133 | C<eio_poll> until it returns something C<!= -1>. |
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134 | |
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135 | A full-featured wrapper would look as follows (if C<eio_poll> is handling |
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136 | all requests, it can of course be simplified a lot by removing the idle |
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137 | watcher logic): |
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138 | |
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139 | static struct ev_loop *loop; |
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140 | static ev_idle repeat_watcher; |
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141 | static ev_async ready_watcher; |
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142 | |
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143 | /* idle watcher callback, only used when eio_poll */ |
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144 | /* didn't handle all results in one call */ |
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145 | static void |
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146 | repeat (EV_P_ ev_idle *w, int revents) |
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147 | { |
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148 | if (eio_poll () != -1) |
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149 | ev_idle_stop (EV_A_ w); |
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150 | } |
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151 | |
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152 | /* eio has some results, process them */ |
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153 | static void |
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154 | ready (EV_P_ ev_async *w, int revents) |
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155 | { |
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156 | if (eio_poll () == -1) |
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157 | ev_idle_start (EV_A_ &repeat_watcher); |
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158 | } |
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159 | |
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160 | /* wake up the event loop */ |
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161 | static void |
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162 | want_poll (void) |
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163 | { |
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164 | ev_async_send (loop, &ready_watcher) |
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165 | } |
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166 | |
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167 | void |
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168 | my_init_eio () |
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169 | { |
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170 | loop = EV_DEFAULT; |
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171 | |
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172 | ev_idle_init (&repeat_watcher, repeat); |
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173 | ev_async_init (&ready_watcher, ready); |
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174 | ev_async_start (loop &watcher); |
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175 | |
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176 | eio_init (want_poll, 0); |
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177 | } |
| 134 | |
178 | |
| 135 | For most other event loops, you would typically use a pipe - the event |
179 | For most other event loops, you would typically use a pipe - the event |
| 136 | loop should be told to wait for read readiness on the read end. In |
180 | loop should be told to wait for read readiness on the read end. In |
| 137 | C<want_poll> you would write a single byte, in C<done_poll> you would try |
181 | C<want_poll> you would write a single byte, in C<done_poll> you would try |
| 138 | to read that byte, and in the callback for the read end, you would call |
182 | to read that byte, and in the callback for the read end, you would call |
