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Commit c573a3d7 authored by Mike Yu's avatar Mike Yu
Browse files

Retrieve the res_stats based on a given list of nameserver addresses 

Similar to aosp/1136436, each independent lookup thread should get
the stats based on its own nameserver address list rather than the
list stored in NetConfig.

With this change, plus aosp/1136436, it's able to populate nameserver
addresses in random order to lookup threads without the worry of
breaking the legacy stats stored in NetConfig.

Bug: 137169582
Test: cd packages/modules/DnsResolver && atest
Change-Id: I8d5c639326d2931bf7e5f5ae668e7aba830e00fb
parent e48f7b54

res_cache.cpp

+23 −6
Original line number Diff line number Diff line
@@ -1786,18 +1786,35 @@ uint32_t resolv_cache_get_subsampling_denom(unsigned netid, int return_code) { 
    return denom;

}



int resolv_cache_get_resolver_stats(unsigned netid, res_params* params, res_stats stats[MAXNS]) {

int resolv_cache_get_resolver_stats(unsigned netid, res_params* params, res_stats stats[MAXNS],

                                    const std::vector<IPSockAddr>& serverSockAddrs) {

    std::lock_guard guard(cache_mutex);

    NetConfig* info = find_netconfig_locked(netid);

    if (info) {

        memcpy(stats, info->nsstats, sizeof(info->nsstats));

        *params = info->params;

        return info->revision_id;

    }

    if (!info) return -1;



    for (size_t i = 0; i < serverSockAddrs.size(); i++) {

        for (size_t j = 0; j < info->nameserverSockAddrs.size(); j++) {

            // Should never happen. Just in case because of the fix-sized array |stats|.

            if (j >= MAXNS) {

                LOG(WARNING) << __func__ << ": unexpected size " << j;

                return -1;

            }



            // It's possible that the server is not found, e.g. when a new list of nameservers

            // is updated to the NetConfig just after this look up thread being populated.

            // Keep the server valid as-is (by means of keeping stats[i] unset), but we should

            // think about if there's a better way.

            if (info->nameserverSockAddrs[j] == serverSockAddrs[i]) {

                stats[i] = info->nsstats[j];

                break;

            }

        }

    }



    *params = info->params;

    return info->revision_id;

}



void resolv_cache_add_resolver_stats_sample(unsigned netid, int revision_id,

                                            const IPSockAddr& serverSockAddr,

                                            const res_sample& sample, int max_samples) {

res_send.cpp

+2 −2
Original line number Diff line number Diff line
@@ -460,9 +460,9 @@ int res_nsend(res_state statp, const uint8_t* buf, int buflen, uint8_t* ans, int 
        }

    }



    res_stats stats[MAXNS];

    res_stats stats[MAXNS]{};

    res_params params;

    int revision_id = resolv_cache_get_resolver_stats(statp->netid, &params, stats);

    int revision_id = resolv_cache_get_resolver_stats(statp->netid, &params, stats, statp->nsaddrs);

    if (revision_id < 0) {

        // TODO: Remove errno once callers stop using it

        errno = ESRCH;

resolv_private.h

+4 −2
Original line number Diff line number Diff line
@@ -120,9 +120,11 @@ struct ResState { 
typedef ResState* res_state;



/* Retrieve a local copy of the stats for the given netid. The buffer must have space for

 * MAXNS __resolver_stats. Returns the revision id of the resolvers used.

 * MAXNS res_stats. Returns the revision id of the resolvers used or -1 on failure.

 */

int resolv_cache_get_resolver_stats(unsigned netid, res_params* params, res_stats stats[MAXNS]);

int resolv_cache_get_resolver_stats(

        unsigned netid, res_params* params, res_stats stats[MAXNS],

        const std::vector<android::netdutils::IPSockAddr>& serverSockAddrs);



/* Add a sample to the shared struct for the given netid and server, provided that the

 * revision_id of the stored servers has not changed.