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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 <algorithm>
     12 #include <stdio.h>
     13 #include <sys/time.h>
     14 #include <time.h>
     15 #include "leveldb/env.h"
     16 
     17 namespace leveldb {
     18 
     19 class 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