neobytes/util/posix_logger.h

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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// Logger implementation that can be shared by all environments
// where enough Posix functionality is available.
#ifndef STORAGE_LEVELDB_UTIL_POSIX_LOGGER_H_
#define STORAGE_LEVELDB_UTIL_POSIX_LOGGER_H_
#include <algorithm>
#include <stdio.h>
#include <sys/time.h>
#include <time.h>
#include "leveldb/env.h"
namespace leveldb {
class PosixLogger : public Logger {
private:
FILE* file_;
uint64_t (*gettid_)(); // Return the thread id for the current thread
public:
PosixLogger(FILE* f, uint64_t (*gettid)()) : file_(f), gettid_(gettid) { }
virtual ~PosixLogger() {
fclose(file_);
}
virtual void Logv(const char* format, va_list ap) {
const uint64_t thread_id = (*gettid_)();
// We try twice: the first time with a fixed-size stack allocated buffer,
// and the second time with a much larger dynamically allocated buffer.
char buffer[500];
for (int iter = 0; iter < 2; iter++) {
char* base;
int bufsize;
if (iter == 0) {
bufsize = sizeof(buffer);
base = buffer;
} else {
bufsize = 30000;
base = new char[bufsize];
}
char* p = base;
char* limit = base + bufsize;
struct timeval now_tv;
gettimeofday(&now_tv, NULL);
const time_t seconds = now_tv.tv_sec;
struct tm t;
localtime_r(&seconds, &t);
p += snprintf(p, limit - p,
"%04d/%02d/%02d-%02d:%02d:%02d.%06d %llx ",
t.tm_year + 1900,
t.tm_mon + 1,
t.tm_mday,
t.tm_hour,
t.tm_min,
t.tm_sec,
static_cast<int>(now_tv.tv_usec),
static_cast<long long unsigned int>(thread_id));
// Print the message
if (p < limit) {
va_list backup_ap;
va_copy(backup_ap, ap);
p += vsnprintf(p, limit - p, format, backup_ap);
va_end(backup_ap);
}
// Truncate to available space if necessary
if (p >= limit) {
if (iter == 0) {
continue; // Try again with larger buffer
} else {
p = limit - 1;
}
}
// Add newline if necessary
if (p == base || p[-1] != '\n') {
*p++ = '\n';
}
assert(p <= limit);
fwrite(base, 1, p - base, file_);
fflush(file_);
if (base != buffer) {
delete[] base;
}
break;
}
}
};
} // namespace leveldb
#endif // STORAGE_LEVELDB_UTIL_POSIX_LOGGER_H_