dc9a03e855 — curl

Subject

multi: multi_wait fixes after #20832

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Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

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Commit Diff GitHub →

lib/multi.c +40 -40

lib/multi.c+40 -40

@@ -254,6 +254,10 @@ struct Curl_multi *Curl_multi_handle(uint32_t xfer_table_size,
	multi->multiplexing = TRUE;
	multi->max_concurrent_streams = 100;
	multi->last_timeout_ms = -1;
+	#ifdef ENABLE_WAKEUP
+	multi->wakeup_pair[0] = CURL_SOCKET_BAD;
+	multi->wakeup_pair[1] = CURL_SOCKET_BAD;
+	#endif

	if(Curl_mntfy_resize(multi) \|\|
	Curl_uint32_bset_resize(&multi->process, xfer_table_size) \|\|
@@ -296,10 +300,10 @@ struct Curl_multi *Curl_multi_handle(uint32_t xfer_table_size,
	goto error;
	#endif
	#ifdef ENABLE_WAKEUP
-	if(Curl_wakeup_init(multi->wakeup_pair, TRUE) < 0) {
-	multi->wakeup_pair[0] = CURL_SOCKET_BAD;
-	multi->wakeup_pair[1] = CURL_SOCKET_BAD;
-	}
+	/* When enabled, rely on this to work. We ignore this in previous
+	* versions, but that seems an unnecessary complication. */
+	if(Curl_wakeup_init(multi->wakeup_pair, TRUE) < 0)
+	goto error;
	#endif

	#ifdef USE_IPV6
@@ -345,6 +349,9 @@ error:
	Curl_uint32_bset_destroy(&multi->pending);
	Curl_uint32_bset_destroy(&multi->msgsent);
	Curl_uint32_tbl_destroy(&multi->xfers);
+	#ifdef ENABLE_WAKEUP
+	Curl_wakeup_destroy(multi->wakeup_pair);
+	#endif

	curlx_free(multi);
	return NULL;
@@ -1135,8 +1142,7 @@ CURLMcode Curl_multi_pollset(struct Curl_easy *data,
	/* The admin handle always listens on the wakeup socket when there
	* are transfers alive. */
	if(data->multi && (data == data->multi->admin) &&
-	data->multi->xfers_alive &&
-	(data->multi->wakeup_pair[0] != CURL_SOCKET_BAD)) {
+	data->multi->xfers_alive) {
	result = Curl_pollset_add_in(data, ps, data->multi->wakeup_pair[0]);
	}
	#endif
@@ -1365,7 +1371,7 @@ static CURLMcode multi_winsock_select(struct Curl_multi *multi,
	struct curl_waitfd extra_fds[],
	unsigned int extra_nfds,
	int timeout_ms,
-	bool wait_on_nop,
+	bool extrawait,
	int *pnevents)
	{
	CURLMcode mresult = CURLM_OK;
@@ -1394,7 +1400,7 @@ static CURLMcode multi_winsock_select(struct Curl_multi *multi,
	}
	}

-	if(cpfds->n \|\| wait_on_nop) {
+	if(cpfds->n \|\| extrawait) {
	int pollrc = 0;

	if(cpfds->n) { /* pre-check with Winsock */
@@ -1475,13 +1481,14 @@ static CURLMcode multi_posix_poll(struct Curl_multi *multi,
	struct curl_waitfd extra_fds[],
	unsigned int extra_nfds,
	int timeout_ms,
-	bool wait_on_nop,
+	bool extrawait,
	int *pnevents)
	{
	CURLMcode mresult = CURLM_OK;
	int nevents = 0;
	size_t i;

+	(void)multi;
	if(cpfds->n) {
	int pollrc = Curl_poll(cpfds->pfds, cpfds->n, timeout_ms); /* wait... */
	if(pollrc < 0) {
@@ -1505,21 +1512,11 @@ static CURLMcode multi_posix_poll(struct Curl_multi *multi,
	extra_fds[i].revents = (short)mask;
	}
	}
-	else if(wait_on_nop) {
-	struct curltime expire_time;
-	long sleep_ms = 0;
-
-	/* Avoid busy-looping when there is nothing particular to wait for */
-	multi_timeout(multi, &expire_time, &sleep_ms);
-	if(sleep_ms) {
-	if(sleep_ms > timeout_ms)
-	sleep_ms = timeout_ms;
-	/* when there are no easy handles in the multi, this holds a -1
-	timeout */
-	else if(sleep_ms < 0)
-	sleep_ms = timeout_ms;
-	curlx_wait_ms(sleep_ms);
-	}
+	else if(extrawait) {
+	/* No fds to poll, but asked to obey timeout_ms anyway. We cannot
+	* use Curl_poll() as it, on some platforms, returns immediately
+	* without fds. */
+	curlx_wait_ms(timeout_ms);
	}

	out:
@@ -1536,8 +1533,7 @@ static CURLMcode multi_wait(struct Curl_multi *multi,
	unsigned int extra_nfds,
	int timeout_ms,
	int *ret,
-	bool wait_on_nop) /* spend time, even if there
-	* is nothing to monitor */
+	bool extrawait) /* when no socket, wait */
	{
	size_t i;
	struct curltime expire_time;
@@ -1590,7 +1586,11 @@ static CURLMcode multi_wait(struct Curl_multi *multi,
	}

	#ifdef ENABLE_WAKEUP
-	if(wait_on_nop && multi->wakeup_pair[0] != CURL_SOCKET_BAD) {
+	/* If `extrawait` is TRUE or we have `extra_fds`to poll or we
+	* have transfer sockets to poll, we obey `timeout_ms`.
+	* Then we need to also monitor the multi's wakeup
+	* socket to catch calls to `curl_multi_wakeup()` during the wait. */
+	if(extrawait \|\| cpfds.n \|\| extra_nfds) {
	wakeup_idx = cpfds.n;
	if(Curl_pollfds_add_sock(&cpfds, multi->wakeup_pair[0], POLLIN)) {
	mresult = CURLM_OUT_OF_MEMORY;
@@ -1618,7 +1618,9 @@ static CURLMcode multi_wait(struct Curl_multi *multi,
	/* We check the internal timeout AFTER we collected all sockets to
	* poll. Collecting the sockets may install new timers by protocols
	* and connection filters.
-	* Use the shorter one of the internal and the caller requested timeout. */
+	* Use the shorter one of the internal and the caller requested timeout.
+	* If we are called with `!extrawait` and multi_timeout() reports no
+	* timeouts exist, do not wait. */
	multi_timeout(multi, &expire_time, &timeout_internal);
	if((timeout_internal >= 0) && (timeout_internal < (long)timeout_ms))
	timeout_ms = (int)timeout_internal;
@@ -1630,11 +1632,11 @@ static CURLMcode multi_wait(struct Curl_multi *multi,
	#ifdef USE_WINSOCK
	mresult = multi_winsock_select(multi, &cpfds, curl_nfds,
	extra_fds, extra_nfds,
-	timeout_ms, wait_on_nop, &nevents);
+	timeout_ms, extrawait, &nevents);
	#else
	mresult = multi_posix_poll(multi, &cpfds, curl_nfds,
	extra_fds, extra_nfds,
-	timeout_ms, wait_on_nop, &nevents);
+	timeout_ms, extrawait, &nevents);
	#endif

	#ifdef ENABLE_WAKEUP
@@ -1679,26 +1681,24 @@ CURLMcode curl_multi_wakeup(CURLM *m)
	it has to be careful only to access parts of the
	Curl_multi struct that are constant */
	struct Curl_multi *multi = m;
+	CURLMcode mresult = CURLM_WAKEUP_FAILURE;

	/* GOOD_MULTI_HANDLE can be safely called */
	if(!GOOD_MULTI_HANDLE(multi))
	return CURLM_BAD_HANDLE;

-	#ifdef USE_WINSOCK
-	if(WSASetEvent(multi->wsa_event))
-	return CURLM_OK;
-	#endif
	#ifdef ENABLE_WAKEUP
	/* the wakeup_pair variable is only written during init and cleanup,
	making it safe to access from another thread after the init part
	and before cleanup */
-	if(multi->wakeup_pair[1] != CURL_SOCKET_BAD) {
-	if(Curl_wakeup_signal(multi->wakeup_pair))
-	return CURLM_WAKEUP_FAILURE;
-	return CURLM_OK;
-	}
+	if(!Curl_wakeup_signal(multi->wakeup_pair))
+	mresult = CURLM_OK;
	#endif
-	return CURLM_WAKEUP_FAILURE;
+	#ifdef USE_WINSOCK
+	if(WSASetEvent(multi->wsa_event))
+	mresult = CURLM_OK;
+	#endif
+	return mresult;
	}

	/*