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change from isc_nmhandle_ref/unref to isc_nmhandle attach/detach

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Attaching and detaching handle pointers will make it easier to
determine where and why reference counting errors have occurred.

A handle needs to be referenced more than once when multiple
asynchronous operations are in flight, so callers must now maintain
multiple handle pointers for each pending operation. For example,
ns_client objects now contain:

        - reqhandle:    held while waiting for a request callback (query,
                        notify, update)
        - sendhandle:   held while waiting for a send callback
        - fetchhandle:  held while waiting for a recursive fetch to
                        complete
        - updatehandle: held while waiting for an update-forwarding
                        task to complete

control channel connection objects now contain:

        - readhandle: held while waiting for a read callback
        - sendhandle: held while waiting for a send callback
        - cmdhandle:  held while an rndc command is running

httpd connections contain:

        - readhandle: held while waiting for a read callback
        - sendhandle: held while waiting for a send callback
This commit is contained in:
Evan Hunt
2020-09-03 13:31:27 -07:00
parent cfa4ea64bc
commit 57b4dde974
26 changed files with 416 additions and 309 deletions
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31
lib/isc/httpd.c
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@@ -75,7 +75,10 @@ struct isc_httpd {
isc_httpdmgr_t *mgr; /*%< our parent */
ISC_LINK(isc_httpd_t) link;
isc_nmhandle_t *handle;
isc_nmhandle_t *handle; /* Permanent pointer to handle */
isc_nmhandle_t *readhandle; /* Waiting for a read callback */
isc_nmhandle_t *sendhandle; /* Waiting for a send callback */
state_t state;
int flags;
@@ -636,6 +639,7 @@ new_httpd(isc_httpdmgr_t *httpdmgr, isc_nmhandle_t *handle) {
if (httpd->handle == NULL) {
isc_nmhandle_setdata(handle, httpd, httpd_reset, httpd_put);
httpd->handle = handle;
} else {
INSIST(httpd->handle == handle);
}
@@ -663,10 +667,10 @@ new_httpd(isc_httpdmgr_t *httpdmgr, isc_nmhandle_t *handle) {
ISC_LIST_APPEND(httpdmgr->running, httpd, link);
UNLOCK(&httpdmgr->lock);
isc_nmhandle_ref(handle);
isc_nmhandle_attach(handle, &httpd->readhandle);
result = isc_nm_read(handle, httpd_request, httpdmgr);
if (result != ISC_R_SUCCESS) {
isc_nmhandle_unref(handle);
isc_nmhandle_detach(&httpd->readhandle);
}
return (result);
@@ -849,7 +853,7 @@ httpd_request(isc_nmhandle_t *handle, isc_result_t eresult,
REQUIRE(httpd->state == RECV);
if (eresult != ISC_R_SUCCESS) {
goto done;
goto cleanup_readhandle;
}
result = process_request(httpd, region);
@@ -858,9 +862,9 @@ httpd_request(isc_nmhandle_t *handle, isc_result_t eresult,
/* don't unref, continue reading */
return;
}
goto done;
goto cleanup_readhandle;
} else if (result != ISC_R_SUCCESS) {
goto done;
goto cleanup_readhandle;
}
isc_buffer_initnull(&httpd->bodybuffer);
@@ -958,18 +962,18 @@ httpd_request(isc_nmhandle_t *handle, isc_result_t eresult,
isc_nm_pauseread(handle);
httpd->state = SEND;
isc_nmhandle_ref(handle);
isc_nmhandle_attach(handle, &httpd->sendhandle);
result = isc_nm_send(handle, &r, httpd_senddone, httpd);
if (result != ISC_R_SUCCESS) {
isc_nm_resumeread(handle);
isc_nmhandle_unref(handle);
isc_nmhandle_detach(&httpd->sendhandle);
httpd->state = RECV;
isc_nm_resumeread(handle);
}
return;
done:
isc_nmhandle_unref(handle);
cleanup_readhandle:
isc_nmhandle_detach(&httpd->readhandle);
}
void
@@ -990,7 +994,7 @@ isc_httpdmgr_shutdown(isc_httpdmgr_t **httpdmgrp) {
httpd = ISC_LIST_HEAD(httpdmgr->running);
while (httpd != NULL) {
isc_nmhandle_unref(httpd->handle);
isc_nm_cancelread(httpd->readhandle);
httpd = ISC_LIST_NEXT(httpd, link);
}
UNLOCK(&httpdmgr->lock);
@@ -1137,9 +1141,10 @@ httpd_senddone(isc_nmhandle_t *handle, isc_result_t result, void *arg) {
return;
}
isc_nmhandle_detach(&httpd->sendhandle);
httpd->state = RECV;
isc_nm_resumeread(handle);
isc_nmhandle_unref(handle);
}
isc_result_t