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 "base/files/file.h"
   9 #include "base/format_macros.h"
  10 #include "base/strings/string_util.h"
  11 #include "base/time/time.h"
  12 #include "third_party/leveldatabase/src/include/leveldb/env.h"
  13
  14 namespace leveldb {
  15
  16 class ChromiumLogger : public Logger {
  17  public:
  18   explicit ChromiumLogger(base::File* f) : file_(f) {}
  19   virtual ~ChromiumLogger() {}
  20   virtual void Logv(const char* format, va_list ap) {
  21     const base::PlatformThreadId thread_id = base::PlatformThread::CurrentId();
  22
  23     // We try twice: the first time with a fixed-size stack allocated buffer,
  24     // and the second time with a much larger dynamically allocated buffer.
  25     char buffer[500];
  26     for (int iter = 0; iter < 2; iter++) {
  27       char* base;
  28       int bufsize;
  29       if (iter == 0) {
  30         bufsize = sizeof(buffer);
  31         base = buffer;
  32       } else {
  33         bufsize = 30000;
  34         base = new char[bufsize];
  35       }
  36       char* p = base;
  37       char* limit = base + bufsize;
  38
  39       base::Time::Exploded t;
  40       base::Time::Now().LocalExplode(&t);
  41
  42       p += base::snprintf(p, limit - p,
  43                     "%04d/%02d/%02d-%02d:%02d:%02d.%03d %" PRIu64 " ",
  44                     t.year,
  45                     t.month,
  46                     t.day_of_month,
  47                     t.hour,
  48                     t.minute,
  49                     t.second,
  50                     t.millisecond,
  51                     static_cast<uint64>(thread_id));
  52
  53       // Print the message
  54       if (p < limit) {
  55         va_list backup_ap;
  56         va_copy(backup_ap, ap);
  57         p += vsnprintf(p, limit - p, format, backup_ap);
  58         va_end(backup_ap);
  59       }
  60
  61       // Truncate to available space if necessary
  62       if (p >= limit) {
  63         if (iter == 0) {
  64           continue;       // Try again with larger buffer
  65         } else {
  66           p = limit - 1;
  67         }
  68       }
  69
  70       // Add newline if necessary
  71       if (p == base || p[-1] != '\n') {
  72         *p++ = '\n';
  73       }
  74
  75       assert(p <= limit);
  76       file_->WriteAtCurrentPos(base, p - base);
  77       if (base != buffer) {
  78         delete[] base;
  79       }
  80       break;
  81     }
  82   }
  83
  84  private:
  85   scoped_ptr<base::File> file_;
  86 };
  87
  88 }  // namespace leveldb
  89
  90 #endif  // THIRD_PARTY_LEVELDATABASE_CHROMIUM_LOGGER_H_