free(host->hcps.prlist_val);
host->hcps.prlist_val = NULL;
host->hcps.prlist_len = 0;
- free(host->tmay_caps.Capabilities_val);
- host->tmay_caps.Capabilities_val = NULL;
- host->tmay_caps.Capabilities_len = 0;
DeleteAllCallBacks_r(host, 1);
host->hostFlags &= ~RESETDONE; /* just to be safe */
return 0;
}
-/*
- * The following few functions deal with caching TellMeAboutYourself calls
- * that we issued to clients. Why do we do this? Well:
- *
- * Q: First, why do we need to issue a TMAY against a client on an incoming new
- * Rx connection?
- *
- * A: We must verify that the incoming Rx connection is the same host that
- * we have a 'host' structure for. On new calls for existing connections, we
- * can remember which host corresponds to that connection, but for new
- * connections, we have no way to find what host it is for, except by looking
- * up the host by IP address. Since hosts can change IP addresses, we need to
- * contact the IP address to see if it's the host we think it is.
- *
- * Q: Okay, then why cache the results?
- *
- * A: The TMAY calls to a single host are serialized, because they are issued
- * with the host's host->lock held. If we get 4 Rx calls each on new
- * connections to the same host at the same time, the 1st call will lock the
- * host, and issue a TMAY. Once that's done, the second call will issue a
- * TMAY, then the 3rd and then the 4th. However, the 3rd and 4th calls have
- * been waiting to issue a TMAY since before the 2nd call even _started_ to
- * issue a TMAY. So, we can just effectively give the results of the 2nd
- * call's TMAY to the 3rd and 4th, too. Since it is nondeterministic which of
- * those calls gets to issue a TMAY "first", we can just assume they all got
- * the same result.
- *
- * Note that in the above example, we cannot reuse the results of the 1st TMAY
- * for the 2nd, 3rd, and 4th calls (we only reuse the results of the 2nd).
- * This is because by the time the 2nd call starts waiting for the host lock,
- * it doesn't know how long the 1st TMAY has been running, so the 2nd call
- * might indeed get a different TMAY result (though this probably would be
- * extremely rare).
- *
- * Anyway, so, if we don't cache the results, we are issuing TMAYs that are
- * pure overhead. In an environment with clients that create a lot of
- * connections to a fileserver (keep in mind each new PAG on OpenAFS clients
- * creates a new connection), this can mean a significant amount of overhead.
- * So, we use this "TMAY cache" to avoid this overhead for the common case.
- */
-/**
- * Should we skip calling TellMeAboutYourself on this host, and instead rely
- * on cached TMAY results?
- *
- * @param[in] host The host we are dealing with
- * @param[in] prewait_tmays What the value of host->n_tmays was _before_ we
- * locked 'host'
- * @param[in] prewait_host What the primary IP address for 'host' was before
- * we locked 'host'
- * @param[in] prewait_port What the primary port was for 'host' before we
- * locked 'host'
- *
- * @return Whether we should skip calling TMAY, and instead rely on cached
- * results in host
- */
-static int
-ShouldSkipTMAY(struct host *host, int prewait_tmays, afs_uint32 prewait_host,
- afs_uint16 prewait_port)
-{
- int skiptmay = 0;
- if (host->n_tmays > prewait_tmays + 1) {
- /* while we were waiting for the host lock, the in-progress TMAY
- * call finished, someone else started a new TMAY call, and that
- * finished. so, calling TMAY again won't give us any information
- * or additional guarantees. */
- skiptmay = 1;
- }
- if (host->host != prewait_host || host->port != prewait_port) {
- /* ...but don't skip it if the host has changed */
- skiptmay = 0;
- }
- return skiptmay;
-}
-
-/**
- * If appropriate, simulate a TellMeAboutYourself call on 'host' by extracting
- * cached interfaceAddr and Capabilities information from 'host' itself.
- *
- * @param[in] host The host we're dealing with
- * @param[inout] askiptmay On entering this function, this should contain the
- * result of ShouldSkipTMAY. On return, it is 1 if we
- * actually did use cached TMAY results, or 0 if we
- * did not.
- * @param[out] interf The interfaceAddr result of the simulated TMAY call
- * @param[out] caps The Capabilities result of the simulated TMAY call
- *
- * @return status
- * @retval 0 We used the cached TMAY results; do NOT make a real TMAY request
- * @retval otherwise We did not use cached TMAY results; issue a real TMAY request
- */
-static int
-SimulateTMAY(struct host *host, int *askiptmay, struct interfaceAddr *interf,
- Capabilities *caps)
-{
- size_t capsize;
-
- if (!*askiptmay) {
- /* we're not supposed to skip the actual TMAY call */
- return -1;
- }
-
- *interf = host->tmay_interf;
-
- free(caps->Capabilities_val);
- caps->Capabilities_val = NULL;
- caps->Capabilities_len = 0;
-
- if (!host->tmay_caps.Capabilities_val) {
- return 0;
- }
-
- capsize = sizeof(caps->Capabilities_val[0]) * host->tmay_caps.Capabilities_len;
-
- caps->Capabilities_val = malloc(capsize);
- if (!caps->Capabilities_val) {
- /* we should/did _not_ skip the real TMAY call, since we couldn't
- * alloc memory to use the cached results */
- *askiptmay = 0;
- return -1;
- }
- caps->Capabilities_len = host->tmay_caps.Capabilities_len;
- memcpy(caps->Capabilities_val, host->tmay_caps.Capabilities_val, capsize);
-
- return 0;
-}
-
-/**
- * If appropriate, store the given results from a real TellmeAboutYourself
- * call, and cache them in the given host structure.
- *
- * @param[in] host The host we're dealing with
- * @param[in] skiptmay 1 if we skipped making a real TMAY call, 0 otherwise
- * @param[in] didtmay 1 if we issued a successful real TMAY call, 0 otherwise
- * @param[in] interf The interfaceAddr result from the real TMAY call
- * @param[in] caps The Capabilities result from the real TMAY call
- */
-static void
-CacheTMAY(struct host *host, int skiptmay, int didtmay,
- struct interfaceAddr *interf, Capabilities *caps)
-{
- size_t capsize;
-
- if (skiptmay) {
- /* we simulated the TMAY call, so the state of the world hasn't
- * changed; don't touch anything */
- return;
- }
- if (!didtmay) {
- /* we did not perform a successful TMAY, so we don't have valid
- * results to cache. blow away the existing cache so we don't use
- * stale results */
- goto resetcache;
- }
- if (host->n_tmays == INT_MAX) {
- /* make sure int rollover doesn't screw up our ordering */
- goto resetcache;
- }
- if (host->lock.num_waiting == 0) {
- /* nobody is waiting for this host, so no reason to cache anything */
- goto resetcache;
- }
-
- /* okay, if we got here, everything looks good; let's cache the given
- * 'interf' and 'caps' */
-
- host->tmay_interf = *interf;
-
- if (!caps->Capabilities_val) {
- free(host->tmay_caps.Capabilities_val);
- host->tmay_caps.Capabilities_val = NULL;
- host->tmay_caps.Capabilities_len = 0;
-
- } else {
- if (caps->Capabilities_len != host->tmay_caps.Capabilities_len) {
- free(host->tmay_caps.Capabilities_val);
- host->tmay_caps.Capabilities_val = NULL;
- host->tmay_caps.Capabilities_len = 0;
- }
-
- capsize = sizeof(caps->Capabilities_val[0]) * caps->Capabilities_len;
-
- if (!host->tmay_caps.Capabilities_val) {
- host->tmay_caps.Capabilities_val = malloc(capsize);
- if (!host->tmay_caps.Capabilities_val) {
- goto resetcache;
- }
- }
-
- host->tmay_caps.Capabilities_len = caps->Capabilities_len;
- memcpy(host->tmay_caps.Capabilities_val, caps->Capabilities_val, capsize);
- }
- host->n_tmays++;
- return;
-
- resetcache:
- /* blow away the cached TMAY data; pretend we never saw anything */
- free(host->tmay_caps.Capabilities_val);
- host->tmay_caps.Capabilities_val = NULL;
- host->tmay_caps.Capabilities_len = 0;
- memset(&host->tmay_interf, 0, sizeof(host->tmay_interf));
-
- host->n_tmays = 0;
-}
static int
h_threadquota(int waiting)
* structure for this address. Verify that the identity
* of the caller matches the identity in the host structure.
*/
-
- int didtmay = 0; /* did we make a successful TMAY call against host->host? */
- unsigned int prewait_tmays;
- afs_uint32 prewait_host;
- afs_uint16 prewait_port;
- int skiptmay;
-
if ((host->hostFlags & HWHO_INPROGRESS) &&
h_threadquota(host->lock.num_waiting)) {
h_Release_r(host);
host = NULL;
goto gethost_out;
}
-
- prewait_tmays = host->n_tmays;
- prewait_host = host->host;
- prewait_port = host->port;
-
h_Lock_r(host);
if (!(host->hostFlags & ALTADDR) ||
(host->hostFlags & HOSTDELETED)) {
cb_conn = host->callback_rxcon;
rx_GetConnection(cb_conn);
-
- skiptmay = ShouldSkipTMAY(host, prewait_tmays, prewait_host, prewait_port);
-
H_UNLOCK;
if (haddr == host->host && hport == host->port) {
/* The existing callback connection matches the
* incoming connection so just use it.
*/
-
- if (SimulateTMAY(host, &skiptmay, &interf, &caps) == 0) {
- /* noop; we don't need to call TellMeAboutYourself; we can
- * trust the results from the last TMAY call */
- code = 0;
-
- } else {
- code =
- RXAFSCB_TellMeAboutYourself(cb_conn, &interf, &caps);
- if (code == RXGEN_OPCODE)
- code = RXAFSCB_WhoAreYou(cb_conn, &interf);
- if (code == 0) {
- didtmay = 1;
- }
- }
+ code =
+ RXAFSCB_TellMeAboutYourself(cb_conn, &interf, &caps);
+ if (code == RXGEN_OPCODE)
+ code = RXAFSCB_WhoAreYou(cb_conn, &interf);
} else {
/* We do not have a match. Create a new connection
* for the new addr/port and use multi_Rx to probe
rx_PutConnection(cb_conn);
cb_conn=NULL;
H_LOCK;
-
- CacheTMAY(host, skiptmay, didtmay, &interf, &caps);
-
if ((code == RXGEN_OPCODE) ||
((code == 0) && (afs_uuid_equal(&interf.uuid, &nulluuid)))) {
identP = (struct Identity *)malloc(sizeof(struct Identity));
projects / packages / o / openafs.git / commitdiff