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/*
* Copyright (C) 2020 The Android Open Source Project
*
* 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.
*/
#pragma once
#include <sys/types.h>
#include "LogWriter.h"
#include "SerializedData.h"
#include "SerializedLogEntry.h"
class SerializedLogChunk {
public:
explicit SerializedLogChunk(size_t size) : contents_(size) {}
SerializedLogChunk(SerializedLogChunk&& other) noexcept = default;
~SerializedLogChunk();
void Compress();
void IncReaderRefCount();
// Decrease the reader ref count and compress the log if appropriate. `compress` should only be
// set to false in the case that the log buffer will be deleted afterwards.
void DecReaderRefCount(bool compress);
// Must have no readers referencing this. Return true if there are no logs left in this chunk.
bool ClearUidLogs(uid_t uid, log_id_t log_id, LogStatistics* stats);
bool CanLog(size_t len);
SerializedLogEntry* Log(uint64_t sequence, log_time realtime, uid_t uid, pid_t pid, pid_t tid,
const char* msg, uint16_t len);
// If this buffer has been compressed, we only consider its compressed size when accounting for
// memory consumption for pruning. This is since the uncompressed log is only by used by
// readers, and thus not a representation of how much these logs cost to keep in memory.
size_t PruneSize() const {
return sizeof(*this) + (compressed_log_.size() ?: contents_.size());
}
void FinishWriting() {
writer_active_ = false;
if (reader_ref_count_ == 0) {
Compress();
}
}
const SerializedLogEntry* log_entry(int offset) const {
return reinterpret_cast<const SerializedLogEntry*>(data() + offset);
}
const uint8_t* data() const { return contents_.data(); }
int write_offset() const { return write_offset_; }
uint64_t highest_sequence_number() const { return highest_sequence_number_; }
// Exposed for testing
uint32_t reader_ref_count() const { return reader_ref_count_; }
private:
// The decompressed contents of this log buffer. Deallocated when the ref_count reaches 0 and
// writer_active_ is false.
SerializedData contents_;
int write_offset_ = 0;
uint32_t reader_ref_count_ = 0;
bool writer_active_ = true;
uint64_t highest_sequence_number_ = 1;
SerializedData compressed_log_;
};
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