third_party/leveldatabase/chromium_logger.h

   1 // Copyright (c) 2012 The Chromium 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.
   4
   5 #ifndef THIRD_PARTY_LEVELDATABASE_CHROMIUM_LOGGER_H_
   6 #define THIRD_PARTY_LEVELDATABASE_CHROMIUM_LOGGER_H_
   7
   8 #include <algorithm>
   9 #include <stdio.h>
  10 #include "base/format_macros.h"
  11 #include "base/strings/string_util.h"
  12 #include "base/time/time.h"
  13 #include "leveldb/env.h"
  14
  15 namespace leveldb {
  16
  17 class ChromiumLogger : public Logger {
  18  public:
  19   ChromiumLogger(FILE* f) : file_(f) { }
  20   virtual ~ChromiumLogger() {
  21     fclose(file_);
  22   }
  23   virtual void Logv(const char* format, va_list ap) {
  24     const long long unsigned int thread_id =
  25         ::base::PlatformThread::CurrentId();
  26
  27     // We try twice: the first time with a fixed-size stack allocated buffer,
  28     // and the second time with a much larger dynamically allocated buffer.
  29     char buffer[500];
  30     for (int iter = 0; iter < 2; iter++) {
  31       char* base;
  32       int bufsize;
  33       if (iter == 0) {
  34         bufsize = sizeof(buffer);
  35         base = buffer;
  36       } else {
  37         bufsize = 30000;
  38         base = new char[bufsize];
  39       }
  40       char* p = base;
  41       char* limit = base + bufsize;
  42
  43       ::base::Time::Exploded t;
  44       ::base::Time::Now().LocalExplode(&t);
  45
  46       p += ::base::snprintf(p, limit - p,
  47                     "%04d/%02d/%02d-%02d:%02d:%02d.%03d %"PRIu64" ",
  48                     t.year,
  49                     t.month,
  50                     t.day_of_month,
  51                     t.hour,
  52                     t.minute,
  53                     t.second,
  54                     t.millisecond,
  55                     thread_id);
  56
  57       // Print the message
  58       if (p < limit) {
  59         va_list backup_ap;
  60         GG_VA_COPY(backup_ap, ap);
  61         p += vsnprintf(p, limit - p, format, backup_ap);
  62         va_end(backup_ap);
  63       }
  64
  65       // Truncate to available space if necessary
  66       if (p >= limit) {
  67         if (iter == 0) {
  68           continue;       // Try again with larger buffer
  69         } else {
  70           p = limit - 1;
  71         }
  72       }
  73
  74       // Add newline if necessary
  75       if (p == base || p[-1] != '\n') {
  76         *p++ = '\n';
  77       }
  78
  79       assert(p <= limit);
  80       fwrite(base, 1, p - base, file_);
  81       fflush(file_);
  82       if (base != buffer) {
  83         delete[] base;
  84       }
  85       break;
  86     }
  87   }
  88  private:
  89   FILE* file_;
  90 };
  91
  92 }  // namespace leveldb
  93
  94 #endif  // THIRD_PARTY_LEVELDATABASE_CHROMIUM_LOGGER_H_