80 lines
2.6 KiB
C++
80 lines
2.6 KiB
C++
//
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// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2021
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#pragma once
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#include "td/utils/common.h"
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#include "td/utils/logging.h"
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#include "td/utils/Slice.h"
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#include <atomic>
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#include <cstdio>
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#include <cstring>
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namespace td {
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template <int buffer_size = 32 * (1 << 10)>
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class MemoryLog final : public LogInterface {
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static constexpr size_t MAX_OUTPUT_SIZE = buffer_size / 16 < (8 << 10) ? buffer_size / 16 : (8 << 10);
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static_assert((buffer_size & (buffer_size - 1)) == 0, "Buffer size must be power of 2");
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static_assert(buffer_size >= (8 << 10), "Too small buffer size");
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public:
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MemoryLog() {
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std::memset(buffer_, ' ', sizeof(buffer_));
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}
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Slice get_buffer() const {
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return Slice(buffer_, sizeof(buffer_));
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}
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size_t get_pos() const {
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return pos_ & (buffer_size - 1);
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}
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private:
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void do_append(int log_level, CSlice new_slice) final {
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Slice slice = new_slice;
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slice.truncate(MAX_OUTPUT_SIZE);
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while (!slice.empty() && slice.back() == '\n') {
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slice.remove_suffix(1);
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}
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size_t slice_size = slice.size();
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CHECK(slice_size * 3 < buffer_size);
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size_t pad_size = ((slice_size + 15) & ~15) - slice_size;
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constexpr size_t MAGIC_SIZE = 16;
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auto total_size = static_cast<uint32>(slice_size + pad_size + MAGIC_SIZE);
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auto real_pos = pos_.fetch_add(total_size, std::memory_order_relaxed);
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CHECK((total_size & 15) == 0);
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uint32 start_pos = real_pos & (buffer_size - 1);
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uint32 end_pos = start_pos + total_size;
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if (likely(end_pos <= buffer_size)) {
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std::memcpy(&buffer_[start_pos + MAGIC_SIZE], slice.data(), slice_size);
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std::memcpy(&buffer_[start_pos + MAGIC_SIZE + slice_size], " ", pad_size);
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} else {
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size_t first = buffer_size - start_pos - MAGIC_SIZE;
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size_t second = slice_size - first;
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std::memcpy(&buffer_[start_pos + MAGIC_SIZE], slice.data(), first);
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std::memcpy(&buffer_[0], slice.data() + first, second);
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std::memcpy(&buffer_[second], " ", pad_size);
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}
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CHECK((start_pos & 15) == 0);
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CHECK(start_pos <= buffer_size - MAGIC_SIZE);
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buffer_[start_pos] = '\n';
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size_t printed = std::snprintf(&buffer_[start_pos + 1], MAGIC_SIZE - 1, "LOG:%08x: ", real_pos);
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CHECK(printed == MAGIC_SIZE - 2);
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buffer_[start_pos + MAGIC_SIZE - 1] = ' ';
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}
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char buffer_[buffer_size];
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std::atomic<uint32> pos_{0};
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};
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} // namespace td
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