1/*
2 *
3 * Copyright 2017, The Android Open Source Project
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 *     http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18#ifndef ANDROID_TYPED_LOGGER_H
19#define ANDROID_TYPED_LOGGER_H
20
21#include <media/nbaio/NBLog.h>
22#include <algorithm>
23
24/*
25Fowler-Noll-Vo (FNV-1a) hash function for the file name.
26Hashes at compile time. FNV-1a iterative function:
27
28hash = offset_basis
29for each byte to be hashed
30        hash = hash xor byte
31        hash = hash * FNV_prime
32return hash
33
34offset_basis and FNV_prime values depend on the size of the hash output
35Following values are defined by FNV and should not be changed arbitrarily
36*/
37
38template<typename T>
39constexpr T offset_basis();
40
41template<typename T>
42constexpr T FNV_prime();
43
44template<>
45constexpr uint32_t offset_basis<uint32_t>() {
46    return 2166136261u;
47}
48
49template<>
50constexpr uint32_t FNV_prime<uint32_t>() {
51    return 16777619u;
52}
53
54template<>
55constexpr uint64_t offset_basis<uint64_t>() {
56    return 14695981039346656037ull;
57}
58
59template<>
60constexpr uint64_t FNV_prime<uint64_t>() {
61    return 1099511628211ull;
62}
63
64template <typename T, size_t n>
65constexpr T fnv1a(const char (&file)[n], int i = n - 1) {
66    return i == -1 ? offset_basis<T>() : (fnv1a<T>(file, i - 1) ^ file[i]) * FNV_prime<T>();
67}
68
69template <size_t n>
70constexpr uint64_t hash(const char (&file)[n], uint32_t line) {
71    // Line numbers over or equal to 2^16 are clamped to 2^16 - 1. This way increases collisions
72    // compared to wrapping around, but is easy to identify because it doesn't produce aliasing.
73    // It's a very unlikely case anyways.
74    return ((fnv1a<uint64_t>(file) << 16) ^ ((fnv1a<uint64_t>(file) >> 32) & 0xFFFF0000)) |
75           std::min(line, 0xFFFFu);
76}
77
78// TODO Permit disabling of logging at compile-time.
79
80// TODO A non-nullptr dummy implementation that is a nop would be faster than checking for nullptr
81//      in the case when logging is enabled at compile-time and enabled at runtime, but it might be
82//      slower than nullptr check when logging is enabled at compile-time and disabled at runtime.
83
84// Write formatted entry to log
85#define LOGT(fmt, ...) do { NBLog::Writer *x = tlNBLogWriter; if (x != nullptr) \
86                                x->logFormat((fmt), hash(__FILE__, __LINE__), ##__VA_ARGS__); } \
87                                while (0)
88
89// Write histogram timestamp entry
90#define LOG_HIST_TS() do { NBLog::Writer *x = tlNBLogWriter; if (x != nullptr) \
91        x->logEventHistTs(NBLog::EVENT_HISTOGRAM_ENTRY_TS, hash(__FILE__, __LINE__)); } while(0)
92
93// Record that audio was turned on/off
94#define LOG_AUDIO_STATE() do { NBLog::Writer *x = tlNBLogWriter; if (x != nullptr) \
95        x->logEventHistTs(NBLog::EVENT_AUDIO_STATE, hash(__FILE__, __LINE__)); } while(0)
96
97namespace android {
98extern "C" {
99extern thread_local NBLog::Writer *tlNBLogWriter;
100}
101} // namespace android
102
103#endif // ANDROID_TYPED_LOGGER_H
104