1/*
2 * Copyright (C) 2016 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef _RESOLVER_STATS_H_
18#define _RESOLVER_STATS_H_
19
20#include <time.h>
21
22namespace android {
23namespace net {
24
25struct ResolverStats {
26    // Offsets into the per-server resolver stats as encoded in vector<int32_t> stats of
27    // getResolverInfo() of Netd's binder interface. The stats are based on data reported by
28    // android_net_res_stats_get_info_for_net(), the usability is calculated by applying
29    // android_net_res_stats_get_usable_servers() to this data.
30    enum ResolverStatsOffsets {
31        STATS_SUCCESSES = 0,    // # successes counted for this server
32        STATS_ERRORS,           // # errors
33        STATS_TIMEOUTS,         // # timeouts
34        STATS_INTERNAL_ERRORS,  // # internal errors
35        STATS_RTT_AVG,          // average round-trip-time
36        STATS_LAST_SAMPLE_TIME, // time in s when the last sample was recorded
37        STATS_USABLE,           // whether the server is considered usable
38        STATS_COUNT             // total count of integers in the per-server data
39    };
40
41    int successes {-1};
42    int errors {-1};
43    int timeouts {-1};
44    int internal_errors {-1};
45    int rtt_avg {-1};
46    time_t last_sample_time {0};
47    bool usable {false};
48
49    // Serialize the resolver stats to the end of |out|.
50    void encode(std::vector<int32_t>* out) const;
51
52    // Read the serialized resolverstats starting at |in[ofs]|.
53    ssize_t decode(const std::vector<int32_t>& in, ssize_t ofs);
54
55    // Serialize the contents of |stats| and append them to the end of |out|. Multiple arrays
56    // can be written to the same output vector in sequence, however, the corresponding call
57    // to decodeAll() will return the combined contents in one vector.
58    static void encodeAll(const std::vector<ResolverStats>& stats, std::vector<int32_t>* out);
59
60    // Decodes the serialized ResolverStats from |in| and appends them to stats.
61    static bool decodeAll(const std::vector<int32_t>& in, std::vector<ResolverStats>* stats);
62};
63
64
65inline void ResolverStats::encode(std::vector<int32_t>* out) const {
66    size_t ofs = out->size();
67    out->resize(ofs + STATS_COUNT);
68    int32_t* cur = &(*out)[ofs];
69    cur[STATS_SUCCESSES] = successes;
70    cur[STATS_ERRORS] = errors;
71    cur[STATS_TIMEOUTS] = timeouts;
72    cur[STATS_INTERNAL_ERRORS] = internal_errors;
73    cur[STATS_RTT_AVG] = rtt_avg;
74    cur[STATS_LAST_SAMPLE_TIME] = last_sample_time;
75    cur[STATS_USABLE] = usable;
76}
77
78    // Read the serialized resolverstats starting at |in[ofs]|.
79inline ssize_t ResolverStats::decode(const std::vector<int32_t>& in, ssize_t ofs) {
80    if (ofs < 0 || static_cast<size_t>(ofs) + STATS_COUNT > in.size()) {
81        return -1;
82    }
83    const int32_t* cur = &in[ofs];
84    successes = cur[STATS_SUCCESSES];
85    errors = cur[STATS_ERRORS];
86    timeouts = cur[STATS_TIMEOUTS];
87    internal_errors = cur[STATS_INTERNAL_ERRORS];
88    rtt_avg = cur[STATS_RTT_AVG];
89    last_sample_time = cur[STATS_LAST_SAMPLE_TIME];
90    usable = cur[STATS_USABLE];
91    return ofs + STATS_COUNT;
92}
93
94inline void ResolverStats::encodeAll(const std::vector<ResolverStats>& stats,
95        std::vector<int32_t>* out) {
96    for (const auto& s : stats) {
97        s.encode(out);
98    }
99}
100
101// TODO: Replace with a better representation, e.g. a Parcelable.
102inline bool ResolverStats::decodeAll(const std::vector<int32_t>& in,
103        std::vector<ResolverStats>* stats) {
104    ssize_t size = in.size();
105    if (size % STATS_COUNT) {
106        return false;
107    }
108    stats->resize(size / STATS_COUNT);
109    ssize_t ofs = 0;
110    for (auto& s : *stats) {
111        ofs = s.decode(in, ofs);
112        if (ofs < 0) {
113            return false;
114        }
115    }
116    return true;
117}
118
119}  // namespace net
120}  // namespace android
121
122#endif /* _RESOLVER_STATS_H_ */
123