114 lines
3.7 KiB
C++
114 lines
3.7 KiB
C++
/*
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* Copyright (C) 2020 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "SerializedLogChunk.h"
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#include <android-base/logging.h>
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#include "CompressionEngine.h"
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SerializedLogChunk::~SerializedLogChunk() {
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CHECK_EQ(reader_ref_count_, 0U);
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}
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void SerializedLogChunk::Compress() {
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if (compressed_log_.size() == 0) {
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CompressionEngine::GetInstance().Compress(contents_, write_offset_, compressed_log_);
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LOG(INFO) << "Compressed Log, buffer max size: " << contents_.size()
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<< " size used: " << write_offset_
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<< " compressed size: " << compressed_log_.size();
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}
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contents_.Resize(0);
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}
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// TODO: Develop a better reference counting strategy to guard against the case where the writer is
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// much faster than the reader, and we needlessly compess / decompress the logs.
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void SerializedLogChunk::IncReaderRefCount() {
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if (++reader_ref_count_ != 1 || writer_active_) {
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return;
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}
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contents_.Resize(write_offset_);
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CompressionEngine::GetInstance().Decompress(compressed_log_, contents_);
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}
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void SerializedLogChunk::DecReaderRefCount(bool compress) {
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CHECK_NE(reader_ref_count_, 0U);
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if (--reader_ref_count_ != 0) {
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return;
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}
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if (compress && !writer_active_) {
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Compress();
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}
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}
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bool SerializedLogChunk::ClearUidLogs(uid_t uid, log_id_t log_id, LogStatistics* stats) {
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CHECK_EQ(reader_ref_count_, 0U);
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if (write_offset_ == 0) {
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return true;
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}
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IncReaderRefCount();
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int read_offset = 0;
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int new_write_offset = 0;
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while (read_offset < write_offset_) {
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const auto* entry = log_entry(read_offset);
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if (entry->uid() == uid) {
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read_offset += entry->total_len();
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if (stats != nullptr) {
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stats->Subtract(entry->ToLogStatisticsElement(log_id));
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}
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continue;
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}
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size_t entry_total_len = entry->total_len();
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if (read_offset != new_write_offset) {
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memmove(contents_.data() + new_write_offset, contents_.data() + read_offset,
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entry_total_len);
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}
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read_offset += entry_total_len;
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new_write_offset += entry_total_len;
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}
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if (new_write_offset == 0) {
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DecReaderRefCount(false);
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return true;
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}
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// Clear the old compressed logs and set write_offset_ appropriately for DecReaderRefCount()
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// to compress the new partially cleared log.
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if (new_write_offset != write_offset_) {
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compressed_log_.Resize(0);
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write_offset_ = new_write_offset;
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}
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DecReaderRefCount(true);
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return false;
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}
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bool SerializedLogChunk::CanLog(size_t len) {
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return write_offset_ + len <= contents_.size();
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}
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SerializedLogEntry* SerializedLogChunk::Log(uint64_t sequence, log_time realtime, uid_t uid,
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pid_t pid, pid_t tid, const char* msg, uint16_t len) {
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auto new_log_address = contents_.data() + write_offset_;
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auto* entry = new (new_log_address) SerializedLogEntry(uid, pid, tid, sequence, realtime, len);
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memcpy(entry->msg(), msg, len);
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write_offset_ += entry->total_len();
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highest_sequence_number_ = sequence;
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return entry;
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} |