platform_system_core/logd/LogBuffer.h
Tom Cherry 855c7c87a3 logd: create FlushToState class
ChattyLogBuffer::FlushTo() needs an array of pid_t's to differentiate
between deduplication and spam removal chatty messages, but that won't
be useful to other log buffers, so it doesn't deserve its own entry in
the abstruct LogBuffer::FlushTo() function.

Other log buffers may need their own data stored for each reader, so
we create an interface that the reader itself owns and passes to the
log buffer.  It uses a unique_ptr, such that the when the reader is
destroyed, so will this state.

FlushToState will additionally contain the start point, that it will
increment itself and the log mask, which LogBuffers can use to
efficiently keep track of the next elements that will be read during a
call to FlushTo().

Side benefit: this allows ChattyLogBufferTests to correctly report
'identical' instead of 'expired' lines the deduplication tests.

Side benefit #2: This updates LogReaderThread::start() more
aggressively, which should result in readers being disconnected less
often, particularly readers who read only a certain UID.

Test: logging unit tests
Change-Id: I969565eb2996afb1431f20e7ccaaa906fcb8f6d1
2020-06-01 14:45:02 -07:00

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2.3 KiB
C++

/*
* 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 <functional>
#include <log/log.h>
#include <log/log_read.h>
#include "LogWriter.h"
// A mask to represent which log buffers a reader is watching, values are (1 << LOG_ID_MAIN), etc.
using LogMask = uint32_t;
constexpr uint32_t kLogMaskAll = 0xFFFFFFFF;
// State that a LogBuffer may want to persist across calls to FlushTo().
class FlushToState {
public:
FlushToState(uint64_t start, LogMask log_mask) : start_(start), log_mask_(log_mask) {}
virtual ~FlushToState() {}
uint64_t start() const { return start_; }
void set_start(uint64_t start) { start_ = start; }
LogMask log_mask() const { return log_mask_; }
private:
uint64_t start_;
LogMask log_mask_;
};
// Enum for the return values of the `filter` function passed to FlushTo().
enum class FilterResult {
kSkip,
kStop,
kWrite,
};
class LogBuffer {
public:
virtual ~LogBuffer() {}
virtual void Init() = 0;
virtual int Log(log_id_t log_id, log_time realtime, uid_t uid, pid_t pid, pid_t tid,
const char* msg, uint16_t len) = 0;
virtual std::unique_ptr<FlushToState> CreateFlushToState(uint64_t start, LogMask log_mask) = 0;
virtual bool FlushTo(LogWriter* writer, FlushToState& state,
const std::function<FilterResult(log_id_t log_id, pid_t pid,
uint64_t sequence, log_time realtime,
uint16_t dropped_count)>& filter) = 0;
virtual bool Clear(log_id_t id, uid_t uid) = 0;
virtual unsigned long GetSize(log_id_t id) = 0;
virtual int SetSize(log_id_t id, unsigned long size) = 0;
virtual uint64_t sequence() const = 0;
};