tdlight/tdutils/td/utils/MemoryLog.h

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//
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// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2024
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#pragma once
#include "td/utils/common.h"
#include "td/utils/logging.h"
#include "td/utils/Slice.h"
#include <atomic>
#include <cstdio>
#include <cstring>
namespace td {
template <int buffer_size = 32 * (1 << 10)>
class MemoryLog final : public LogInterface {
static constexpr size_t MAX_OUTPUT_SIZE = buffer_size / 16 < (8 << 10) ? buffer_size / 16 : (8 << 10);
static_assert((buffer_size & (buffer_size - 1)) == 0, "Buffer size must be power of 2");
static_assert(buffer_size >= (8 << 10), "Too small buffer size");
public:
MemoryLog() {
std::memset(buffer_, ' ', sizeof(buffer_));
}
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Slice get_buffer() const {
return Slice(buffer_, sizeof(buffer_));
}
size_t get_pos() const {
return pos_ & (buffer_size - 1);
}
private:
void do_append(int log_level, CSlice new_slice) final {
Slice slice = new_slice;
slice.truncate(MAX_OUTPUT_SIZE);
while (!slice.empty() && slice.back() == '\n') {
slice.remove_suffix(1);
}
size_t slice_size = slice.size();
CHECK(slice_size * 3 < buffer_size);
size_t pad_size = ((slice_size + 15) & ~15) - slice_size;
constexpr size_t MAGIC_SIZE = 16;
auto total_size = static_cast<uint32>(slice_size + pad_size + MAGIC_SIZE);
auto real_pos = pos_.fetch_add(total_size, std::memory_order_relaxed);
CHECK((total_size & 15) == 0);
uint32 start_pos = real_pos & (buffer_size - 1);
uint32 end_pos = start_pos + total_size;
if (likely(end_pos <= buffer_size)) {
std::memcpy(&buffer_[start_pos + MAGIC_SIZE], slice.data(), slice_size);
std::memcpy(&buffer_[start_pos + MAGIC_SIZE + slice_size], " ", pad_size);
} else {
size_t first = buffer_size - start_pos - MAGIC_SIZE;
size_t second = slice_size - first;
std::memcpy(&buffer_[start_pos + MAGIC_SIZE], slice.data(), first);
std::memcpy(&buffer_[0], slice.data() + first, second);
std::memcpy(&buffer_[second], " ", pad_size);
}
CHECK((start_pos & 15) == 0);
CHECK(start_pos <= buffer_size - MAGIC_SIZE);
buffer_[start_pos] = '\n';
size_t printed = std::snprintf(&buffer_[start_pos + 1], MAGIC_SIZE - 1, "LOG:%08x: ", real_pos);
CHECK(printed == MAGIC_SIZE - 2);
buffer_[start_pos + MAGIC_SIZE - 1] = ' ';
}
char buffer_[buffer_size];
std::atomic<uint32> pos_{0};
};
} // namespace td