Commit | Line | Data |
---|---|---|
7f918cf1 CE |
1 | <!DOCTYPE html>\r |
2 | <html lang="en">\r | |
3 | <head>\r | |
4 | <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">\r | |
5 | <meta name="generator" content="AsciiDoc 8.6.9">\r | |
6 | <title>MLtonSignal</title>\r | |
7 | <link rel="stylesheet" href="./asciidoc.css" type="text/css">\r | |
8 | <link rel="stylesheet" href="./pygments.css" type="text/css">\r | |
9 | \r | |
10 | \r | |
11 | <script type="text/javascript" src="./asciidoc.js"></script>\r | |
12 | <script type="text/javascript">\r | |
13 | /*<![CDATA[*/\r | |
14 | asciidoc.install();\r | |
15 | /*]]>*/\r | |
16 | </script>\r | |
17 | <link rel="stylesheet" href="./mlton.css" type="text/css">\r | |
18 | </head>\r | |
19 | <body class="article">\r | |
20 | <div id="banner">\r | |
21 | <div id="banner-home">\r | |
22 | <a href="./Home">MLton 20180207</a>\r | |
23 | </div>\r | |
24 | </div>\r | |
25 | <div id="header">\r | |
26 | <h1>MLtonSignal</h1>\r | |
27 | </div>\r | |
28 | <div id="content">\r | |
29 | <div id="preamble">\r | |
30 | <div class="sectionbody">\r | |
31 | <div class="listingblock">\r | |
32 | <div class="content"><div class="highlight"><pre><span class="k">signature</span><span class="w"> </span><span class="n">MLTON_SIGNAL</span><span class="w"> </span><span class="p">=</span><span class="w"></span>\r | |
33 | <span class="w"> </span><span class="k">sig</span><span class="w"></span>\r | |
34 | <span class="w"> </span><span class="k">type</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">Posix</span><span class="p">.</span><span class="n">Signal</span><span class="p">.</span><span class="n">signal</span><span class="w"></span>\r | |
35 | <span class="w"> </span><span class="k">type</span><span class="w"> </span><span class="n">signal</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">t</span><span class="w"></span>\r | |
36 | \r | |
37 | <span class="w"> </span><span class="k">structure</span><span class="w"> </span><span class="n">Handler</span><span class="p">:</span><span class="w"></span>\r | |
38 | <span class="w"> </span><span class="k">sig</span><span class="w"></span>\r | |
39 | <span class="w"> </span><span class="k">type</span><span class="w"> </span><span class="n">t</span><span class="w"></span>\r | |
40 | \r | |
41 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">default</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"></span>\r | |
42 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">handler</span><span class="p">:</span><span class="w"> </span><span class="p">(</span><span class="n">Thread</span><span class="p">.</span><span class="n">Runnable</span><span class="p">.</span><span class="n">t</span><span class="w"> </span><span class="p">-></span><span class="w"> </span><span class="n">Thread</span><span class="p">.</span><span class="n">Runnable</span><span class="p">.</span><span class="n">t</span><span class="p">)</span><span class="w"> </span><span class="p">-></span><span class="w"> </span><span class="n">t</span><span class="w"></span>\r | |
43 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">ignore</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"></span>\r | |
44 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">isDefault</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">-></span><span class="w"> </span><span class="n">bool</span><span class="w"></span>\r | |
45 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">isIgnore</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">-></span><span class="w"> </span><span class="n">bool</span><span class="w"></span>\r | |
46 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">simple</span><span class="p">:</span><span class="w"> </span><span class="p">(</span><span class="n">unit</span><span class="w"> </span><span class="p">-></span><span class="w"> </span><span class="n">unit</span><span class="p">)</span><span class="w"> </span><span class="p">-></span><span class="w"> </span><span class="n">t</span><span class="w"></span>\r | |
47 | <span class="w"> </span><span class="k">end</span><span class="w"></span>\r | |
48 | \r | |
49 | <span class="w"> </span><span class="k">structure</span><span class="w"> </span><span class="n">Mask</span><span class="p">:</span><span class="w"></span>\r | |
50 | <span class="w"> </span><span class="k">sig</span><span class="w"></span>\r | |
51 | <span class="w"> </span><span class="k">type</span><span class="w"> </span><span class="n">t</span><span class="w"></span>\r | |
52 | \r | |
53 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">all</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"></span>\r | |
54 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">allBut</span><span class="p">:</span><span class="w"> </span><span class="n">signal</span><span class="w"> </span><span class="n">list</span><span class="w"> </span><span class="p">-></span><span class="w"> </span><span class="n">t</span><span class="w"></span>\r | |
55 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">block</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">-></span><span class="w"> </span><span class="n">unit</span><span class="w"></span>\r | |
56 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">getBlocked</span><span class="p">:</span><span class="w"> </span><span class="n">unit</span><span class="w"> </span><span class="p">-></span><span class="w"> </span><span class="n">t</span><span class="w"></span>\r | |
57 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">isMember</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="n">*</span><span class="w"> </span><span class="n">signal</span><span class="w"> </span><span class="p">-></span><span class="w"> </span><span class="n">bool</span><span class="w"></span>\r | |
58 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">none</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"></span>\r | |
59 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">setBlocked</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">-></span><span class="w"> </span><span class="n">unit</span><span class="w"></span>\r | |
60 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">some</span><span class="p">:</span><span class="w"> </span><span class="n">signal</span><span class="w"> </span><span class="n">list</span><span class="w"> </span><span class="p">-></span><span class="w"> </span><span class="n">t</span><span class="w"></span>\r | |
61 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">unblock</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">-></span><span class="w"> </span><span class="n">unit</span><span class="w"></span>\r | |
62 | <span class="w"> </span><span class="k">end</span><span class="w"></span>\r | |
63 | \r | |
64 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">getHandler</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">-></span><span class="w"> </span><span class="n">Handler</span><span class="p">.</span><span class="n">t</span><span class="w"></span>\r | |
65 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">handled</span><span class="p">:</span><span class="w"> </span><span class="n">unit</span><span class="w"> </span><span class="p">-></span><span class="w"> </span><span class="n">Mask</span><span class="p">.</span><span class="n">t</span><span class="w"></span>\r | |
66 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">prof</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"></span>\r | |
67 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">restart</span><span class="p">:</span><span class="w"> </span><span class="n">bool</span><span class="w"> </span><span class="n">ref</span><span class="w"></span>\r | |
68 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">setHandler</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="n">*</span><span class="w"> </span><span class="n">Handler</span><span class="p">.</span><span class="n">t</span><span class="w"> </span><span class="p">-></span><span class="w"> </span><span class="n">unit</span><span class="w"></span>\r | |
69 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">suspend</span><span class="p">:</span><span class="w"> </span><span class="n">Mask</span><span class="p">.</span><span class="n">t</span><span class="w"> </span><span class="p">-></span><span class="w"> </span><span class="n">unit</span><span class="w"></span>\r | |
70 | <span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">vtalrm</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"></span>\r | |
71 | <span class="w"> </span><span class="k">end</span><span class="w"></span>\r | |
72 | </pre></div></div></div>\r | |
73 | <div class="paragraph"><p>Signals handlers are functions from (runnable) threads to (runnable)\r | |
74 | threads. When a signal arrives, the corresponding signal handler is\r | |
75 | invoked, its argument being the thread that was interrupted by the\r | |
76 | signal. The signal handler runs asynchronously, in its own thread.\r | |
77 | The signal handler returns the thread that it would like to resume\r | |
78 | execution (this is often the thread that it was passed). It is an\r | |
79 | error for a signal handler to raise an exception that is not handled\r | |
80 | within the signal handler itself.</p></div>\r | |
81 | <div class="paragraph"><p>A signal handler is never invoked while the running thread is in a\r | |
82 | critical section (see <a href="MLtonThread">MLtonThread</a>). Invoking a signal handler\r | |
83 | implicitly enters a critical section and the normal return of a signal\r | |
84 | handler implicitly exits the critical section; hence, a signal handler\r | |
85 | is never interrupted by another signal handler.</p></div>\r | |
86 | <div class="ulist"><ul>\r | |
87 | <li>\r | |
88 | <p>\r | |
89 | <span class="monospaced">type t</span>\r | |
90 | </p>\r | |
91 | <div class="paragraph"><p>the type of signals.</p></div>\r | |
92 | </li>\r | |
93 | <li>\r | |
94 | <p>\r | |
95 | <span class="monospaced">type Handler.t</span>\r | |
96 | </p>\r | |
97 | <div class="paragraph"><p>the type of signal handlers.</p></div>\r | |
98 | </li>\r | |
99 | <li>\r | |
100 | <p>\r | |
101 | <span class="monospaced">Handler.default</span>\r | |
102 | </p>\r | |
103 | <div class="paragraph"><p>handles the signal with the default action.</p></div>\r | |
104 | </li>\r | |
105 | <li>\r | |
106 | <p>\r | |
107 | <span class="monospaced">Handler.handler f</span>\r | |
108 | </p>\r | |
109 | <div class="paragraph"><p>returns a handler <span class="monospaced">h</span> such that when a signal <span class="monospaced">s</span> is handled by <span class="monospaced">h</span>,\r | |
110 | <span class="monospaced">f</span> will be passed the thread that was interrupted by <span class="monospaced">s</span> and should\r | |
111 | return the thread that will resume execution.</p></div>\r | |
112 | </li>\r | |
113 | <li>\r | |
114 | <p>\r | |
115 | <span class="monospaced">Handler.ignore</span>\r | |
116 | </p>\r | |
117 | <div class="paragraph"><p>is a handler that will ignore the signal.</p></div>\r | |
118 | </li>\r | |
119 | <li>\r | |
120 | <p>\r | |
121 | <span class="monospaced">Handler.isDefault</span>\r | |
122 | </p>\r | |
123 | <div class="paragraph"><p>returns true if the handler is the default handler.</p></div>\r | |
124 | </li>\r | |
125 | <li>\r | |
126 | <p>\r | |
127 | <span class="monospaced">Handler.isIgnore</span>\r | |
128 | </p>\r | |
129 | <div class="paragraph"><p>returns true if the handler is the ignore handler.</p></div>\r | |
130 | </li>\r | |
131 | <li>\r | |
132 | <p>\r | |
133 | <span class="monospaced">Handler.simple f</span>\r | |
134 | </p>\r | |
135 | <div class="paragraph"><p>returns a handler that executes <span class="monospaced">f ()</span> and does not switch threads.</p></div>\r | |
136 | </li>\r | |
137 | <li>\r | |
138 | <p>\r | |
139 | <span class="monospaced">type Mask.t</span>\r | |
140 | </p>\r | |
141 | <div class="paragraph"><p>the type of signal masks, which are sets of blocked signals.</p></div>\r | |
142 | </li>\r | |
143 | <li>\r | |
144 | <p>\r | |
145 | <span class="monospaced">Mask.all</span>\r | |
146 | </p>\r | |
147 | <div class="paragraph"><p>a mask of all signals.</p></div>\r | |
148 | </li>\r | |
149 | <li>\r | |
150 | <p>\r | |
151 | <span class="monospaced">Mask.allBut l</span>\r | |
152 | </p>\r | |
153 | <div class="paragraph"><p>a mask of all signals except for those in <span class="monospaced">l</span>.</p></div>\r | |
154 | </li>\r | |
155 | <li>\r | |
156 | <p>\r | |
157 | <span class="monospaced">Mask.block m</span>\r | |
158 | </p>\r | |
159 | <div class="paragraph"><p>blocks all signals in <span class="monospaced">m</span>.</p></div>\r | |
160 | </li>\r | |
161 | <li>\r | |
162 | <p>\r | |
163 | <span class="monospaced">Mask.getBlocked ()</span>\r | |
164 | </p>\r | |
165 | <div class="paragraph"><p>gets the signal mask <span class="monospaced">m</span>, i.e. a signal is blocked if and only if it\r | |
166 | is in <span class="monospaced">m</span>.</p></div>\r | |
167 | </li>\r | |
168 | <li>\r | |
169 | <p>\r | |
170 | <span class="monospaced">Mask.isMember (m, s)</span>\r | |
171 | </p>\r | |
172 | <div class="paragraph"><p>returns true if the signal <span class="monospaced">s</span> is in <span class="monospaced">m</span>.</p></div>\r | |
173 | </li>\r | |
174 | <li>\r | |
175 | <p>\r | |
176 | <span class="monospaced">Mask.none</span>\r | |
177 | </p>\r | |
178 | <div class="paragraph"><p>a mask of no signals.</p></div>\r | |
179 | </li>\r | |
180 | <li>\r | |
181 | <p>\r | |
182 | <span class="monospaced">Mask.setBlocked m</span>\r | |
183 | </p>\r | |
184 | <div class="paragraph"><p>sets the signal mask to <span class="monospaced">m</span>, i.e. a signal is blocked if and only if\r | |
185 | it is in <span class="monospaced">m</span>.</p></div>\r | |
186 | </li>\r | |
187 | <li>\r | |
188 | <p>\r | |
189 | <span class="monospaced">Mask.some l</span>\r | |
190 | </p>\r | |
191 | <div class="paragraph"><p>a mask of the signals in <span class="monospaced">l</span>.</p></div>\r | |
192 | </li>\r | |
193 | <li>\r | |
194 | <p>\r | |
195 | <span class="monospaced">Mask.unblock m</span>\r | |
196 | </p>\r | |
197 | <div class="paragraph"><p>unblocks all signals in <span class="monospaced">m</span>.</p></div>\r | |
198 | </li>\r | |
199 | <li>\r | |
200 | <p>\r | |
201 | <span class="monospaced">getHandler s</span>\r | |
202 | </p>\r | |
203 | <div class="paragraph"><p>returns the current handler for signal <span class="monospaced">s</span>.</p></div>\r | |
204 | </li>\r | |
205 | <li>\r | |
206 | <p>\r | |
207 | <span class="monospaced">handled ()</span>\r | |
208 | </p>\r | |
209 | <div class="paragraph"><p>returns the signal mask <span class="monospaced">m</span> corresponding to the currently handled\r | |
210 | signals; i.e., a signal is handled if and only if it is in <span class="monospaced">m</span>.</p></div>\r | |
211 | </li>\r | |
212 | <li>\r | |
213 | <p>\r | |
214 | <span class="monospaced">prof</span>\r | |
215 | </p>\r | |
216 | <div class="paragraph"><p><span class="monospaced">SIGPROF</span>, the profiling signal.</p></div>\r | |
217 | </li>\r | |
218 | <li>\r | |
219 | <p>\r | |
220 | <span class="monospaced">restart</span>\r | |
221 | </p>\r | |
222 | <div class="paragraph"><p>dynamically determines the behavior of interrupted system calls; when\r | |
223 | <span class="monospaced">true</span>, interrupted system calls are restarted; when <span class="monospaced">false</span>,\r | |
224 | interrupted system calls raise <span class="monospaced">OS.SysError</span>.</p></div>\r | |
225 | </li>\r | |
226 | <li>\r | |
227 | <p>\r | |
228 | <span class="monospaced">setHandler (s, h)</span>\r | |
229 | </p>\r | |
230 | <div class="paragraph"><p>sets the handler for signal <span class="monospaced">s</span> to <span class="monospaced">h</span>.</p></div>\r | |
231 | </li>\r | |
232 | <li>\r | |
233 | <p>\r | |
234 | <span class="monospaced">suspend m</span>\r | |
235 | </p>\r | |
236 | <div class="paragraph"><p>temporarily sets the signal mask to <span class="monospaced">m</span> and suspends until an unmasked\r | |
237 | signal is received and handled, at which point <span class="monospaced">suspend</span> resets the\r | |
238 | mask and returns.</p></div>\r | |
239 | </li>\r | |
240 | <li>\r | |
241 | <p>\r | |
242 | <span class="monospaced">vtalrm</span>\r | |
243 | </p>\r | |
244 | <div class="paragraph"><p><span class="monospaced">SIGVTALRM</span>, the signal for virtual timers.</p></div>\r | |
245 | </li>\r | |
246 | </ul></div>\r | |
247 | </div>\r | |
248 | </div>\r | |
249 | <div class="sect1">\r | |
250 | <h2 id="_interruptible_system_calls">Interruptible System Calls</h2>\r | |
251 | <div class="sectionbody">\r | |
252 | <div class="paragraph"><p>Signal handling interacts in a non-trivial way with those functions in\r | |
253 | the <a href="BasisLibrary">Basis Library</a> that correspond directly to\r | |
254 | interruptible system calls (a subset of those functions that may raise\r | |
255 | <span class="monospaced">OS.SysError</span>). The desire is that these functions should have\r | |
256 | predictable semantics. The principal concerns are:</p></div>\r | |
257 | <div class="olist arabic"><ol class="arabic">\r | |
258 | <li>\r | |
259 | <p>\r | |
260 | System calls that are interrupted by signals should, by default, be\r | |
261 | restarted; the alternative is to raise\r | |
262 | </p>\r | |
263 | <div class="listingblock">\r | |
264 | <div class="content"><div class="highlight"><pre><span class="n">OS</span><span class="p">.</span><span class="n">SysError</span><span class="w"> </span><span class="p">(</span><span class="n">Posix</span><span class="p">.</span><span class="n">Error</span><span class="p">.</span><span class="n">errorMsg</span><span class="w"> </span><span class="n">Posix</span><span class="p">.</span><span class="n">Error</span><span class="p">.</span><span class="n">intr</span><span class="p">,</span><span class="w"></span>\r | |
265 | <span class="w"> </span><span class="n">SOME</span><span class="w"> </span><span class="n">Posix</span><span class="p">.</span><span class="n">Error</span><span class="p">.</span><span class="n">intr</span><span class="p">)</span><span class="w"></span>\r | |
266 | </pre></div></div></div>\r | |
267 | <div class="paragraph"><p>This behavior is determined dynamically by the value of <span class="monospaced">Signal.restart</span>.</p></div>\r | |
268 | </li>\r | |
269 | <li>\r | |
270 | <p>\r | |
271 | Signal handlers should always get a chance to run (when outside a\r | |
272 | critical region). If a system call is interrupted by a signal, then\r | |
273 | the signal handler will run before the call is restarted or\r | |
274 | <span class="monospaced">OS.SysError</span> is raised; that is, before the <span class="monospaced">Signal.restart</span> check.\r | |
275 | </p>\r | |
276 | </li>\r | |
277 | <li>\r | |
278 | <p>\r | |
279 | A system call that must be restarted while in a critical section\r | |
280 | will be restarted with the handled signals blocked (and the previously\r | |
281 | blocked signals remembered). This encourages the system call to\r | |
282 | complete, allowing the program to make progress towards leaving the\r | |
283 | critical section where the signal can be handled. If the system call\r | |
284 | completes, the set of blocked signals are restored to those previously\r | |
285 | blocked.\r | |
286 | </p>\r | |
287 | </li>\r | |
288 | </ol></div>\r | |
289 | </div>\r | |
290 | </div>\r | |
291 | </div>\r | |
292 | <div id="footnotes"><hr></div>\r | |
293 | <div id="footer">\r | |
294 | <div id="footer-text">\r | |
295 | </div>\r | |
296 | <div id="footer-badges">\r | |
297 | </div>\r | |
298 | </div>\r | |
299 | </body>\r | |
300 | </html>\r |