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logger.cpp
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126 lines (103 loc) · 2.88 KB
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// This file is a part of the IncludeOS unikernel - www.includeos.org
//
// Copyright 2015-2016 Oslo and Akershus University College of Applied Sciences
// and Alfred Bratterud
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <util/logger.hpp>
#include <algorithm>
#include <likely>
Logger::Logger(Log& log, Log::size_type pos)
: log_(log), pos_{&log_, pos}
{
}
void Logger::log(const std::string& str) {
if(UNLIKELY( str.empty() ))
return;
if(UNLIKELY( str.size() + 1 >= (unsigned)log_.size() ))
{
// start at the beginning
pos_ = {&log_, 0};
// calculate offset (with padding)
auto offset = str.size() + 1 - log_.size();
// copy later part into position
std::copy(str.begin() + offset, str.end(), pos_);
// increment position to know where to put padding
pos_ += str.size() - offset;
*pos_ = '\0';
// return to the beginning
++pos_;
return;
}
std::copy(str.begin(), str.end(), pos_);
pos_ += str.size();
// add null terminate padding
auto it = pos_;
while(*it != '\0') {
*it = '\0';
++it;
}
++pos_;
}
std::vector<std::string> Logger::entries() const {
std::vector<std::string> results;
auto head = pos_;
do {
// adjust head
while(*head == '\0') {
++head;
// return results if we went all the way around
if(head == pos_)
return results;
}
std::vector<char> vec;
while(*head != '\0') {
vec.emplace_back(*head);
++head;
}
results.emplace_back(vec.begin(), vec.end());
} while(true);
return results;
}
std::vector<std::string> Logger::entries(size_t n) const {
std::vector<std::string> results;
results.reserve(n);
auto head = pos_;
while(n != 0) {
// adjust head
while(*head == '\0') {
--head;
// return results if we went all the way around
if(head == pos_)
return results;
}
// temporary string
std::vector<char> vec;
do {
// build the string from back to front
vec.emplace_back(*head);
--head;
} while(*head != '\0');
// emplace the string in reverese
results.emplace_back(vec.rbegin(), vec.rend());
// decrement remaining entries
n--;
}
// reverese all the results so it became oldest first
std::reverse(results.begin(), results.end());
return results;
}
void Logger::flush() {
std::fill(log_.begin(), log_.end(), 0);
pos_ = {&log_, 0};
}