mirror of
https://github.com/isc-projects/bind9.git
synced 2026-06-09 09:42:06 -04:00
clarify fctx_cancelquery() behavior
Cleaned up dereferencing of query objects, and added a comment explaining it better.
This commit is contained in:
Evan Hunt
parent
931779b3f6
commit
5948aa7766
1 changed files with 45 additions and 30 deletions
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@ -1214,8 +1214,9 @@ update_edns_stats(resquery_t *query) {
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}
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static void
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fctx_cancelquery(resquery_t *query, isc_time_t *finish, bool no_response,
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fctx_cancelquery(resquery_t **queryp, isc_time_t *finish, bool no_response,
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bool age_untried) {
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resquery_t *query = NULL;
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fetchctx_t *fctx = NULL;
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unsigned int rtt, rttms;
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unsigned int factor;
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@ -1223,6 +1224,9 @@ fctx_cancelquery(resquery_t *query, isc_time_t *finish, bool no_response,
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dns_adbaddrinfo_t *addrinfo;
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isc_stdtime_t now;
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REQUIRE(queryp != NULL);
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query = *queryp;
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fctx = query->fctx;
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FCTXTRACE("cancelquery");
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@ -1401,7 +1405,7 @@ fctx_cancelquery(resquery_t *query, isc_time_t *finish, bool no_response,
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ISC_LIST_UNLINK(fctx->queries, query, link);
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}
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resquery_detach(&query);
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resquery_detach(queryp);
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}
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static void
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@ -1451,7 +1455,7 @@ fctx_cancelqueries(fetchctx_t *fctx, bool no_response, bool age_untried) {
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for (query = ISC_LIST_HEAD(fctx->queries); query != NULL;
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query = next_query) {
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next_query = ISC_LIST_NEXT(query, link);
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fctx_cancelquery(query, NULL, no_response, age_untried);
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fctx_cancelquery(&query, NULL, no_response, age_untried);
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}
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}
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@ -1725,6 +1729,7 @@ fctx_done(fetchctx_t *fctx, isc_result_t result, int line) {
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static void
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resquery_senddone(isc_result_t eresult, isc_region_t *region, void *arg) {
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resquery_t *query = (resquery_t *)arg;
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resquery_t *copy = query;
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fetchctx_t *fctx = NULL;
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QTRACE("senddone");
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@ -1737,6 +1742,10 @@ resquery_senddone(isc_result_t eresult, isc_region_t *region, void *arg) {
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goto detach;
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}
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/*
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* See the note in resquery_connected() about reference
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* counting on error conditions.
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*/
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switch (eresult) {
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case ISC_R_SUCCESS:
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case ISC_R_CANCELED:
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@ -1748,17 +1757,13 @@ resquery_senddone(isc_result_t eresult, isc_region_t *region, void *arg) {
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case ISC_R_NOPERM:
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case ISC_R_ADDRNOTAVAIL:
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case ISC_R_CONNREFUSED:
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/* No route to remote. */
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FCTXTRACE3("query canceled in resquery_senddone(): "
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"no route to host; no response",
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eresult);
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/*
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* No route to remote.
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*/
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add_bad(fctx, query->rmessage, query->addrinfo, eresult,
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badns_unreachable);
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fctx_cancelquery(query, NULL, true, false);
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fctx_cancelquery(©, NULL, true, false);
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FCTX_ATTR_CLR(fctx, FCTX_ATTR_ADDRWAIT);
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fctx_try(fctx, true, false);
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break;
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@ -1767,7 +1772,7 @@ resquery_senddone(isc_result_t eresult, isc_region_t *region, void *arg) {
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FCTXTRACE3("query canceled in resquery_senddone() "
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"due to unexpected result; responding",
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eresult);
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fctx_cancelquery(query, NULL, false, false);
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fctx_cancelquery(©, NULL, false, false);
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fctx_done(fctx, eresult, __LINE__);
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break;
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}
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@ -2744,6 +2749,7 @@ cleanup_temps:
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static void
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resquery_connected(isc_result_t eresult, isc_region_t *region, void *arg) {
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resquery_t *query = (resquery_t *)arg;
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resquery_t *copy = query;
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isc_result_t result;
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fetchctx_t *fctx = NULL;
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dns_resolver_t *res = NULL;
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@ -2766,6 +2772,22 @@ resquery_connected(isc_result_t eresult, isc_region_t *region, void *arg) {
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eresult = ISC_R_SHUTTINGDOWN;
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}
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/*
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* The reference counting of resquery objects is complex:
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*
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* 1. attached in fctx_query()
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* 2. attached prior to dns_dispatch_connect(), detached in
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* resquery_connected()
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* 3. attached prior to dns_dispatch_send(), detached in
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* resquery_senddone()
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* 4. finally detached in fctx_cancelquery()
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*
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* On error conditions, it's necessary to call fctx_cancelquery()
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* from resquery_connected() or _senddone(), detaching twice
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* within the same function. To make it clear that's what's
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* happening, we cancel-and-detach 'copy' and detach 'query',
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* which are both pointing to the same object.
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*/
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switch (eresult) {
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case ISC_R_SUCCESS:
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/*
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@ -2777,7 +2799,7 @@ resquery_connected(isc_result_t eresult, isc_region_t *region, void *arg) {
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FCTXTRACE("query canceled: resquery_send() failed; "
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"responding");
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fctx_cancelquery(query, NULL, false, false);
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fctx_cancelquery(©, NULL, false, false);
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fctx_done(fctx, result, __LINE__);
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break;
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}
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@ -2797,12 +2819,9 @@ resquery_connected(isc_result_t eresult, isc_region_t *region, void *arg) {
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break;
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case ISC_R_CANCELED:
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break;
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case ISC_R_SHUTTINGDOWN:
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FCTXTRACE3("shutdown in resquery_connected(): no response",
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eresult);
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fctx_cancelquery(query, NULL, true, false);
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FCTXTRACE3("shutdown in resquery_connected()", eresult);
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fctx_cancelquery(©, NULL, true, false);
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fctx_done(fctx, eresult, __LINE__);
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break;
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@ -2813,31 +2832,26 @@ resquery_connected(isc_result_t eresult, isc_region_t *region, void *arg) {
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case ISC_R_ADDRNOTAVAIL:
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case ISC_R_CONNECTIONRESET:
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case ISC_R_TIMEDOUT:
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FCTXTRACE3("query canceled in "
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"resquery_connected(): "
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"no route to host; no response",
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eresult);
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/*
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* Do not query this server again in this fetch
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* context if the server is unavailable over
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* TCP.
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* Do not query this server again in this fetch context.
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*/
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FCTXTRACE3("query failed in resquery_connected(): "
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"no response",
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eresult);
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add_bad(fctx, query->rmessage, query->addrinfo, eresult,
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badns_unreachable);
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fctx_cancelquery(query, NULL, true, false);
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fctx_cancelquery(©, NULL, true, false);
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FCTX_ATTR_CLR(fctx, FCTX_ATTR_ADDRWAIT);
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fctx_try(fctx, true, false);
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break;
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default:
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FCTXTRACE3("query canceled in "
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"resquery_connected() "
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FCTXTRACE3("query canceled in resquery_connected() "
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"due to unexpected result; responding",
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eresult);
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fctx_cancelquery(query, NULL, false, false);
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fctx_cancelquery(©, NULL, false, false);
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fctx_done(fctx, eresult, __LINE__);
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break;
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}
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@ -9421,7 +9435,8 @@ rctx_done(respctx_t *rctx, isc_result_t result) {
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if (dns_fuzzing_resolver &&
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(rctx->next_server || rctx->resend || rctx->nextitem))
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{
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fctx_cancelquery(query, rctx->finish, rctx->no_response, false);
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fctx_cancelquery(&query, rctx->finish, rctx->no_response,
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false);
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fctx_done(fctx, DNS_R_SERVFAIL, __LINE__);
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goto detach;
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}
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@ -9438,7 +9453,7 @@ rctx_done(respctx_t *rctx, isc_result_t result) {
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}
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/* Cancel the query */
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fctx_cancelquery(query, rctx->finish, rctx->no_response, false);
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fctx_cancelquery(&query, rctx->finish, rctx->no_response, false);
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/*
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* If nobody's waiting for results, don't resend.
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