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