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* Copyright (C) 2012-2014 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#ifndef _LOGD_LOG_BUFFER_H__
#define _LOGD_LOG_BUFFER_H__
#include <sys/types.h>
#include <list>
#include <string>
#include <android/log.h>
#include <private/android_filesystem_config.h>
#include <sysutils/SocketClient.h>
#include "LogBufferElement.h"
#include "LogBufferInterface.h"
#include "LogStatistics.h"
#include "LogTags.h"
#include "LogTimes.h"
#include "LogWhiteBlackList.h"
// We are either in 1970ish (MONOTONIC) or 2016+ish (REALTIME) so to
// differentiate without prejudice, we use 1972 to delineate, earlier
// is likely monotonic, later is real. Otherwise we start using a
// dividing line between monotonic and realtime if more than a minute
// difference between them.
namespace android {
static bool isMonotonic(const log_time& mono) {
static const uint32_t EPOCH_PLUS_2_YEARS = 2 * 24 * 60 * 60 * 1461 / 4;
static const uint32_t EPOCH_PLUS_MINUTE = 60;
if (mono.tv_sec >= EPOCH_PLUS_2_YEARS) {
return false;
log_time now(CLOCK_REALTIME);
/* Timezone and ntp time setup? */
if (now.tv_sec >= EPOCH_PLUS_2_YEARS) {
return true;
/* no way to differentiate realtime from monotonic time */
if (now.tv_sec < EPOCH_PLUS_MINUTE) {
return false;
log_time cpu(CLOCK_MONOTONIC);
/* too close to call to differentiate monotonic times from realtime */
if ((cpu.tv_sec + EPOCH_PLUS_MINUTE) >= now.tv_sec) {
return false;
/* dividing line half way between monotonic and realtime */
return mono.tv_sec < ((cpu.tv_sec + now.tv_sec) / 2);
typedef std::list<LogBufferElement*> LogBufferElementCollection;
class LogBuffer : public LogBufferInterface {
LogBufferElementCollection mLogElements;
pthread_rwlock_t mLogElementsLock;
LogStatistics stats;
PruneList mPrune;
// watermark for last per log id
LogBufferElementCollection::iterator mLast[LOG_ID_MAX];
bool mLastSet[LOG_ID_MAX];
// watermark of any worst/chatty uid processing
typedef std::unordered_map<uid_t, LogBufferElementCollection::iterator>
LogBufferIteratorMap mLastWorst[LOG_ID_MAX];
// watermark of any worst/chatty pid of system processing
typedef std::unordered_map<pid_t, LogBufferElementCollection::iterator>
LogBufferPidIteratorMap mLastWorstPidOfSystem[LOG_ID_MAX];
unsigned long mMaxSize[LOG_ID_MAX];
bool monotonic;
LogTags tags;
LogBufferElement* lastLoggedElements[LOG_ID_MAX];
LogBufferElement* droppedElements[LOG_ID_MAX];
void log(LogBufferElement* elem);
LastLogTimes& mTimes;
explicit LogBuffer(LastLogTimes* times);
~LogBuffer() override;
void init();
bool isMonotonic() {
return monotonic;
int log(log_id_t log_id, log_time realtime, uid_t uid, pid_t pid, pid_t tid,
const char* msg, unsigned short len) override;
// lastTid is an optional context to help detect if the last previous
// valid message was from the same source so we can differentiate chatty
// filter types (identical or expired)
log_time flushTo(SocketClient* writer, const log_time& start,
pid_t* lastTid, // &lastTid[LOG_ID_MAX] or nullptr
bool privileged, bool security,
int (*filter)(const LogBufferElement* element,
void* arg) = nullptr,
void* arg = nullptr);
bool clear(log_id_t id, uid_t uid = AID_ROOT);
unsigned long getSize(log_id_t id);
int setSize(log_id_t id, unsigned long size);
unsigned long getSizeUsed(log_id_t id);
std::string formatStatistics(uid_t uid, pid_t pid, unsigned int logMask);
void enableStatistics() {
int initPrune(const char* cp) {
return mPrune.init(cp);
std::string formatPrune() {
return mPrune.format();
std::string formatGetEventTag(uid_t uid, const char* name,
const char* format) {
return tags.formatGetEventTag(uid, name, format);
std::string formatEntry(uint32_t tag, uid_t uid) {
return tags.formatEntry(tag, uid);
const char* tagToName(uint32_t tag) {
return tags.tagToName(tag);
// helper must be protected directly or implicitly by wrlock()/unlock()
const char* pidToName(pid_t pid) {
return stats.pidToName(pid);
virtual uid_t pidToUid(pid_t pid) override {
return stats.pidToUid(pid);
virtual pid_t tidToPid(pid_t tid) override {
return stats.tidToPid(tid);
const char* uidToName(uid_t uid) {
return stats.uidToName(uid);
void wrlock() {
void rdlock() {
void unlock() {
static constexpr size_t minPrune = 4;
static constexpr size_t maxPrune = 256;
static const log_time pruneMargin;
void maybePrune(log_id_t id);
bool isBusy(log_time watermark);
void kickMe(LogTimeEntry* me, log_id_t id, unsigned long pruneRows);
bool prune(log_id_t id, unsigned long pruneRows, uid_t uid = AID_ROOT);
LogBufferElementCollection::iterator erase(
LogBufferElementCollection::iterator it, bool coalesce = false);
#endif // _LOGD_LOG_BUFFER_H__