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1 : : // Copyright (c) 2011 The LevelDB Authors. All rights reserved.
2 : : // Use of this source code is governed by a BSD-style license that can be
3 : : // found in the LICENSE file. See the AUTHORS file for names of contributors.
4 : : //
5 : : // Logger implementation that can be shared by all environments
6 : : // where enough posix functionality is available.
7 : :
8 : : #ifndef STORAGE_LEVELDB_UTIL_POSIX_LOGGER_H_
9 : : #define STORAGE_LEVELDB_UTIL_POSIX_LOGGER_H_
10 : :
11 : : #include <sys/time.h>
12 : :
13 : : #include <cassert>
14 : : #include <cstdarg>
15 : : #include <cstdio>
16 : : #include <ctime>
17 : : #include <sstream>
18 : : #include <thread>
19 : :
20 : : #include "leveldb/env.h"
21 : :
22 : : namespace leveldb {
23 : :
24 : : class PosixLogger final : public Logger {
25 : : public:
26 : : // Creates a logger that writes to the given file.
27 : : //
28 : : // The PosixLogger instance takes ownership of the file handle.
29 [ # # ]: 0 : explicit PosixLogger(std::FILE* fp) : fp_(fp) { assert(fp != nullptr); }
30 : :
31 : 0 : ~PosixLogger() override { std::fclose(fp_); }
32 : :
33 : 0 : void Logv(const char* format, va_list arguments) override {
34 : : // Record the time as close to the Logv() call as possible.
35 : 0 : struct ::timeval now_timeval;
36 : 0 : ::gettimeofday(&now_timeval, nullptr);
37 : 0 : const std::time_t now_seconds = now_timeval.tv_sec;
38 : 0 : struct std::tm now_components;
39 : 0 : ::localtime_r(&now_seconds, &now_components);
40 : :
41 : : // Record the thread ID.
42 : 0 : constexpr const int kMaxThreadIdSize = 32;
43 : 0 : std::ostringstream thread_stream;
44 [ # # ]: 0 : thread_stream << std::this_thread::get_id();
45 [ # # ]: 0 : std::string thread_id = thread_stream.str();
46 [ # # # # ]: 0 : if (thread_id.size() > kMaxThreadIdSize) {
47 [ # # ]: 0 : thread_id.resize(kMaxThreadIdSize);
48 : : }
49 : :
50 : : // We first attempt to print into a stack-allocated buffer. If this attempt
51 : : // fails, we make a second attempt with a dynamically allocated buffer.
52 : : constexpr const int kStackBufferSize = 512;
53 : : char stack_buffer[kStackBufferSize];
54 : : static_assert(sizeof(stack_buffer) == static_cast<size_t>(kStackBufferSize),
55 : : "sizeof(char) is expected to be 1 in C++");
56 : :
57 : : int dynamic_buffer_size = 0; // Computed in the first iteration.
58 [ # # ]: 0 : for (int iteration = 0; iteration < 2; ++iteration) {
59 : 0 : const int buffer_size =
60 [ # # ]: 0 : (iteration == 0) ? kStackBufferSize : dynamic_buffer_size;
61 : 0 : char* const buffer =
62 [ # # ]: 0 : (iteration == 0) ? stack_buffer : new char[dynamic_buffer_size];
63 : :
64 : : // Print the header into the buffer.
65 [ # # ]: 0 : int buffer_offset = snprintf(
66 : : buffer, buffer_size, "%04d/%02d/%02d-%02d:%02d:%02d.%06d %s ",
67 : 0 : now_components.tm_year + 1900, now_components.tm_mon + 1,
68 : : now_components.tm_mday, now_components.tm_hour, now_components.tm_min,
69 [ # # ]: 0 : now_components.tm_sec, static_cast<int>(now_timeval.tv_usec),
70 : : thread_id.c_str());
71 : :
72 : : // The header can be at most 28 characters (10 date + 15 time +
73 : : // 3 delimiters) plus the thread ID, which should fit comfortably into the
74 : : // static buffer.
75 [ # # ]: 0 : assert(buffer_offset <= 28 + kMaxThreadIdSize);
76 : 0 : static_assert(28 + kMaxThreadIdSize < kStackBufferSize,
77 : : "stack-allocated buffer may not fit the message header");
78 [ # # ]: 0 : assert(buffer_offset < buffer_size);
79 : :
80 : : // Print the message into the buffer.
81 : 0 : std::va_list arguments_copy;
82 : 0 : va_copy(arguments_copy, arguments);
83 : 0 : buffer_offset +=
84 [ # # ]: 0 : std::vsnprintf(buffer + buffer_offset, buffer_size - buffer_offset,
85 : : format, arguments_copy);
86 : 0 : va_end(arguments_copy);
87 : :
88 : : // The code below may append a newline at the end of the buffer, which
89 : : // requires an extra character.
90 [ # # ]: 0 : if (buffer_offset >= buffer_size - 1) {
91 : : // The message did not fit into the buffer.
92 [ # # ]: 0 : if (iteration == 0) {
93 : : // Re-run the loop and use a dynamically-allocated buffer. The buffer
94 : : // will be large enough for the log message, an extra newline and a
95 : : // null terminator.
96 : 0 : dynamic_buffer_size = buffer_offset + 2;
97 : 0 : continue;
98 : : }
99 : :
100 : : // The dynamically-allocated buffer was incorrectly sized. This should
101 : : // not happen, assuming a correct implementation of (v)snprintf. Fail
102 : : // in tests, recover by truncating the log message in production.
103 : 0 : assert(false);
104 : : buffer_offset = buffer_size - 1;
105 : : }
106 : :
107 : : // Add a newline if necessary.
108 [ # # ]: 0 : if (buffer[buffer_offset - 1] != '\n') {
109 : 0 : buffer[buffer_offset] = '\n';
110 : 0 : ++buffer_offset;
111 : : }
112 : :
113 [ # # ]: 0 : assert(buffer_offset <= buffer_size);
114 [ # # ]: 0 : std::fwrite(buffer, 1, buffer_offset, fp_);
115 [ # # ]: 0 : std::fflush(fp_);
116 : :
117 [ # # ]: 0 : if (iteration != 0) {
118 [ # # ]: 0 : delete[] buffer;
119 : : }
120 : : break;
121 : : }
122 : 0 : }
123 : :
124 : : private:
125 : : std::FILE* const fp_;
126 : : };
127 : :
128 : : } // namespace leveldb
129 : :
130 : : #endif // STORAGE_LEVELDB_UTIL_POSIX_LOGGER_H_
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