<p>laforge <strong>submitted</strong> this change.</p><p><a href="https://gerrit.osmocom.org/c/libosmocore/+/24544">View Change</a></p><div style="white-space:pre-wrap">Approvals:
laforge: Looks good to me, approved
pespin: Looks good to me, but someone else must approve
Jenkins Builder: Verified
</div><pre style="font-family: monospace,monospace; white-space: pre-wrap;">osmo_select_shutdown_request(): allow finishing pending writes on SIGTERM<br><br>Allow telling osmo_select_main* to only service pending writes (shutdown<br>mode). Introduce API fuctions to indicate a shutdown request, and find<br>out whether shutdown is complete.<br><br>Some osmo programs have a curious sleep of few seconds upon receiving<br>SIGTERM. The idea presumably was to finish off pending writes before<br>halting the program. But a sleep() on program exit is annoying,<br>especially when there usually are no pending writes, and when osmo-bsc<br>is launched numerous times for tests.<br><br>Change-Id: Ib94d4316924103459577087c2214188679db2227<br>---<br>M include/osmocom/core/select.h<br>M src/select.c<br>2 files changed, 72 insertions(+), 1 deletion(-)<br><br></pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;"><span>diff --git a/include/osmocom/core/select.h b/include/osmocom/core/select.h</span><br><span>index b410199..e9f19a5 100644</span><br><span>--- a/include/osmocom/core/select.h</span><br><span>+++ b/include/osmocom/core/select.h</span><br><span>@@ -105,5 +105,8 @@</span><br><span> struct osmo_signalfd *</span><br><span> osmo_signalfd_setup(void *ctx, sigset_t set, osmo_signalfd_cb *cb, void *data);</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+void osmo_select_shutdown_request();</span><br><span style="color: hsl(120, 100%, 40%);">+int osmo_select_shutdown_requested();</span><br><span style="color: hsl(120, 100%, 40%);">+bool osmo_select_shutdown_done();</span><br><span> </span><br><span> /*! @} */</span><br><span>diff --git a/src/select.c b/src/select.c</span><br><span>index 71ee7f6..f7eb5ea 100644</span><br><span>--- a/src/select.c</span><br><span>+++ b/src/select.c</span><br><span>@@ -69,6 +69,11 @@</span><br><span> static __thread struct poll_state g_poll;</span><br><span> #endif /* FORCE_IO_SELECT */</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+/*! See osmo_select_shutdown_request() */</span><br><span style="color: hsl(120, 100%, 40%);">+static int _osmo_select_shutdown_requested = 0;</span><br><span style="color: hsl(120, 100%, 40%);">+/*! See osmo_select_shutdown_request() */</span><br><span style="color: hsl(120, 100%, 40%);">+static bool _osmo_select_shutdown_done = false;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> /*! Set up an osmo-fd. Will not register it.</span><br><span> * \param[inout] ofd Osmo FD to be set-up</span><br><span> * \param[in] fd OS-level file descriptor number</span><br><span>@@ -316,6 +321,7 @@</span><br><span> struct osmo_fd *ufd;</span><br><span> unsigned int i;</span><br><span> int work = 0;</span><br><span style="color: hsl(120, 100%, 40%);">+ int shutdown_pending_writes = 0;</span><br><span> </span><br><span> for (i = 0; i < n_fd; i++) {</span><br><span> struct pollfd *p = &g_poll.poll[i];</span><br><span>@@ -340,6 +346,11 @@</span><br><span> /* make sure we never report more than the user requested */</span><br><span> flags &= ufd->when;</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+ if (_osmo_select_shutdown_requested > 0) {</span><br><span style="color: hsl(120, 100%, 40%);">+ if (ufd->when & OSMO_FD_WRITE)</span><br><span style="color: hsl(120, 100%, 40%);">+ shutdown_pending_writes++;</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> if (flags) {</span><br><span> work = 1;</span><br><span> /* make sure to clear any log context before processing the next incoming message</span><br><span>@@ -351,6 +362,9 @@</span><br><span> }</span><br><span> }</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+ if (_osmo_select_shutdown_requested > 0 && !shutdown_pending_writes)</span><br><span style="color: hsl(120, 100%, 40%);">+ _osmo_select_shutdown_done = true;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> return work;</span><br><span> }</span><br><span> </span><br><span>@@ -370,7 +384,8 @@</span><br><span> return 0;</span><br><span> </span><br><span> /* fire timers */</span><br><span style="color: hsl(0, 100%, 40%);">- osmo_timers_update();</span><br><span style="color: hsl(120, 100%, 40%);">+ if (!_osmo_select_shutdown_requested)</span><br><span style="color: hsl(120, 100%, 40%);">+ osmo_timers_update();</span><br><span> </span><br><span> OSMO_ASSERT(osmo_ctx->select);</span><br><span> </span><br><span>@@ -596,6 +611,59 @@</span><br><span> </span><br><span> #endif /* HAVE_SYS_SIGNALFD_H */</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+/*! Request osmo_select_* to only service pending OSMO_FD_WRITE requests. Once all writes are done,</span><br><span style="color: hsl(120, 100%, 40%);">+ * osmo_select_shutdown_done() returns true. This allows for example to send all outbound packets before terminating the</span><br><span style="color: hsl(120, 100%, 40%);">+ * process.</span><br><span style="color: hsl(120, 100%, 40%);">+ *</span><br><span style="color: hsl(120, 100%, 40%);">+ * Usage example:</span><br><span style="color: hsl(120, 100%, 40%);">+ *</span><br><span style="color: hsl(120, 100%, 40%);">+ * static void signal_handler(int signum)</span><br><span style="color: hsl(120, 100%, 40%);">+ * {</span><br><span style="color: hsl(120, 100%, 40%);">+ * fprintf(stdout, "signal %u received\n", signum);</span><br><span style="color: hsl(120, 100%, 40%);">+ *</span><br><span style="color: hsl(120, 100%, 40%);">+ * switch (signum) {</span><br><span style="color: hsl(120, 100%, 40%);">+ * case SIGINT:</span><br><span style="color: hsl(120, 100%, 40%);">+ * case SIGTERM:</span><br><span style="color: hsl(120, 100%, 40%);">+ * // If the user hits Ctrl-C the third time, just terminate immediately.</span><br><span style="color: hsl(120, 100%, 40%);">+ * if (osmo_select_shutdown_requested() >= 2)</span><br><span style="color: hsl(120, 100%, 40%);">+ * exit(-1);</span><br><span style="color: hsl(120, 100%, 40%);">+ * // Request write-only mode in osmo_select_main_ctx()</span><br><span style="color: hsl(120, 100%, 40%);">+ * osmo_select_shutdown_request();</span><br><span style="color: hsl(120, 100%, 40%);">+ * break;</span><br><span style="color: hsl(120, 100%, 40%);">+ * [...]</span><br><span style="color: hsl(120, 100%, 40%);">+ * }</span><br><span style="color: hsl(120, 100%, 40%);">+ *</span><br><span style="color: hsl(120, 100%, 40%);">+ * main()</span><br><span style="color: hsl(120, 100%, 40%);">+ * {</span><br><span style="color: hsl(120, 100%, 40%);">+ * signal(SIGINT, &signal_handler);</span><br><span style="color: hsl(120, 100%, 40%);">+ * signal(SIGTERM, &signal_handler);</span><br><span style="color: hsl(120, 100%, 40%);">+ *</span><br><span style="color: hsl(120, 100%, 40%);">+ * [...]</span><br><span style="color: hsl(120, 100%, 40%);">+ *</span><br><span style="color: hsl(120, 100%, 40%);">+ * // After the signal_handler issued osmo_select_shutdown_request(), osmo_select_shutdown_done() returns true</span><br><span style="color: hsl(120, 100%, 40%);">+ * // as soon as all write queues are empty.</span><br><span style="color: hsl(120, 100%, 40%);">+ * while (!osmo_select_shutdown_done()) {</span><br><span style="color: hsl(120, 100%, 40%);">+ * osmo_select_main_ctx(0);</span><br><span style="color: hsl(120, 100%, 40%);">+ * }</span><br><span style="color: hsl(120, 100%, 40%);">+ * }</span><br><span style="color: hsl(120, 100%, 40%);">+ */</span><br><span style="color: hsl(120, 100%, 40%);">+void osmo_select_shutdown_request()</span><br><span style="color: hsl(120, 100%, 40%);">+{</span><br><span style="color: hsl(120, 100%, 40%);">+ _osmo_select_shutdown_requested++;</span><br><span style="color: hsl(120, 100%, 40%);">+};</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+/*! Return the number of times osmo_select_shutdown_request() was called before. */</span><br><span style="color: hsl(120, 100%, 40%);">+int osmo_select_shutdown_requested()</span><br><span style="color: hsl(120, 100%, 40%);">+{</span><br><span style="color: hsl(120, 100%, 40%);">+ return _osmo_select_shutdown_requested;</span><br><span style="color: hsl(120, 100%, 40%);">+};</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+/*! Return true after osmo_select_shutdown_requested() was called, and after an osmo_select poll loop found no more</span><br><span style="color: hsl(120, 100%, 40%);">+ * pending OSMO_FD_WRITE on any registered socket. */</span><br><span style="color: hsl(120, 100%, 40%);">+bool osmo_select_shutdown_done() {</span><br><span style="color: hsl(120, 100%, 40%);">+ return _osmo_select_shutdown_done;</span><br><span style="color: hsl(120, 100%, 40%);">+};</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> /*! @} */</span><br><span> </span><br><span> #endif /* _HAVE_SYS_SELECT_H */</span><br><span></span><br></pre><p>To view, visit <a href="https://gerrit.osmocom.org/c/libosmocore/+/24544">change 24544</a>. 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<div style="display:none"> Gerrit-Project: libosmocore </div>
<div style="display:none"> Gerrit-Branch: master </div>
<div style="display:none"> Gerrit-Change-Id: Ib94d4316924103459577087c2214188679db2227 </div>
<div style="display:none"> Gerrit-Change-Number: 24544 </div>
<div style="display:none"> Gerrit-PatchSet: 4 </div>
<div style="display:none"> Gerrit-Owner: neels <nhofmeyr@sysmocom.de> </div>
<div style="display:none"> Gerrit-Reviewer: Jenkins Builder </div>
<div style="display:none"> Gerrit-Reviewer: laforge <laforge@osmocom.org> </div>
<div style="display:none"> Gerrit-Reviewer: pespin <pespin@sysmocom.de> </div>
<div style="display:none"> Gerrit-MessageType: merged </div>