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 <algorithm>
12#include <stdio.h>
13#include <sys/time.h>
14#include <time.h>
15#include "leveldb/env.h"
16
17namespace leveldb {
18
19class PosixLogger : public Logger {
20 private:
21  FILE* file_;
22  uint64_t (*gettid_)();  // Return the thread id for the current thread
23 public:
24  PosixLogger(FILE* f, uint64_t (*gettid)()) : file_(f), gettid_(gettid) { }
25  virtual ~PosixLogger() {
26    fclose(file_);
27  }
28  virtual void Logv(const char* format, va_list ap) {
29    const uint64_t thread_id = (*gettid_)();
30
31    // We try twice: the first time with a fixed-size stack allocated buffer,
32    // and the second time with a much larger dynamically allocated buffer.
33    char buffer[500];
34    for (int iter = 0; iter < 2; iter++) {
35      char* base;
36      int bufsize;
37      if (iter == 0) {
38        bufsize = sizeof(buffer);
39        base = buffer;
40      } else {
41        bufsize = 30000;
42        base = new char[bufsize];
43      }
44      char* p = base;
45      char* limit = base + bufsize;
46
47      struct timeval now_tv;
48      gettimeofday(&now_tv, NULL);
49      const time_t seconds = now_tv.tv_sec;
50      struct tm t;
51      localtime_r(&seconds, &t);
52      p += snprintf(p, limit - p,
53                    "%04d/%02d/%02d-%02d:%02d:%02d.%06d %llx ",
54                    t.tm_year + 1900,
55                    t.tm_mon + 1,
56                    t.tm_mday,
57                    t.tm_hour,
58                    t.tm_min,
59                    t.tm_sec,
60                    static_cast<int>(now_tv.tv_usec),
61                    static_cast<long long unsigned int>(thread_id));
62
63      // Print the message
64      if (p < limit) {
65        va_list backup_ap;
66        va_copy(backup_ap, ap);
67        p += vsnprintf(p, limit - p, format, backup_ap);
68        va_end(backup_ap);
69      }
70
71      // Truncate to available space if necessary
72      if (p >= limit) {
73        if (iter == 0) {
74          continue;       // Try again with larger buffer
75        } else {
76          p = limit - 1;
77        }
78      }
79
80      // Add newline if necessary
81      if (p == base || p[-1] != '\n') {
82        *p++ = '\n';
83      }
84
85      assert(p <= limit);
86      fwrite(base, 1, p - base, file_);
87      fflush(file_);
88      if (base != buffer) {
89        delete[] base;
90      }
91      break;
92    }
93  }
94};
95
96}  // namespace leveldb
97
98#endif  // STORAGE_LEVELDB_UTIL_POSIX_LOGGER_H_
99