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platform_system_core/logd/LogBuffer.cpp

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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
*
* 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.
*/
#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <sys/user.h>
#include <time.h>
#include <unistd.h>
#include <unordered_map>
#include <cutils/properties.h>
#include <log/logger.h>
#include "LogBuffer.h"
#include "LogKlog.h"
#include "LogReader.h"
// Default
#define LOG_BUFFER_SIZE (256 * 1024) // Tuned on a per-platform basis here?
#define log_buffer_size(id) mMaxSize[id]
#define LOG_BUFFER_MIN_SIZE (64 * 1024UL)
#define LOG_BUFFER_MAX_SIZE (256 * 1024 * 1024UL)
static bool valid_size(unsigned long value) {
if ((value < LOG_BUFFER_MIN_SIZE) || (LOG_BUFFER_MAX_SIZE < value)) {
return false;
}
long pages = sysconf(_SC_PHYS_PAGES);
if (pages < 1) {
return true;
}
long pagesize = sysconf(_SC_PAGESIZE);
if (pagesize <= 1) {
pagesize = PAGE_SIZE;
}
// maximum memory impact a somewhat arbitrary ~3%
pages = (pages + 31) / 32;
unsigned long maximum = pages * pagesize;
if ((maximum < LOG_BUFFER_MIN_SIZE) || (LOG_BUFFER_MAX_SIZE < maximum)) {
return true;
}
return value <= maximum;
}
static unsigned long property_get_size(const char *key) {
char property[PROPERTY_VALUE_MAX];
property_get(key, property, "");
char *cp;
unsigned long value = strtoul(property, &cp, 10);
switch(*cp) {
case 'm':
case 'M':
value *= 1024;
/* FALLTHRU */
case 'k':
case 'K':
value *= 1024;
/* FALLTHRU */
case '\0':
break;
default:
value = 0;
}
if (!valid_size(value)) {
value = 0;
}
return value;
}
void LogBuffer::init() {
static const char global_tuneable[] = "persist.logd.size"; // Settings App
static const char global_default[] = "ro.logd.size"; // BoardConfig.mk
unsigned long default_size = property_get_size(global_tuneable);
if (!default_size) {
default_size = property_get_size(global_default);
if (!default_size) {
default_size = property_get_bool("ro.config.low_ram",
BOOL_DEFAULT_FALSE)
? LOG_BUFFER_MIN_SIZE // 64K
: LOG_BUFFER_SIZE; // 256K
}
}
log_id_for_each(i) {
char key[PROP_NAME_MAX];
snprintf(key, sizeof(key), "%s.%s",
global_tuneable, android_log_id_to_name(i));
unsigned long property_size = property_get_size(key);
if (!property_size) {
snprintf(key, sizeof(key), "%s.%s",
global_default, android_log_id_to_name(i));
property_size = property_get_size(key);
}
if (!property_size) {
property_size = default_size;
}
if (!property_size) {
property_size = LOG_BUFFER_SIZE;
}
if (setSize(i, property_size)) {
setSize(i, LOG_BUFFER_MIN_SIZE);
}
}
bool lastMonotonic = monotonic;
monotonic = android_log_clockid() == CLOCK_MONOTONIC;
if (lastMonotonic != monotonic) {
//
// Fixup all timestamps, may not be 100% accurate, but better than
// throwing what we have away when we get 'surprised' by a change.
// In-place element fixup so no need to check reader-lock. Entries
// should already be in timestamp order, but we could end up with a
// few out-of-order entries if new monotonics come in before we
// are notified of the reinit change in status. A Typical example would
// be:
// --------- beginning of system
// 10.494082 184 201 D Cryptfs : Just triggered post_fs_data
// --------- beginning of kernel
// 0.000000 0 0 I : Initializing cgroup subsys
// as the act of mounting /data would trigger persist.logd.timestamp to
// be corrected. 1/30 corner case YMMV.
//
pthread_mutex_lock(&mLogElementsLock);
LogBufferElementCollection::iterator it = mLogElements.begin();
while((it != mLogElements.end())) {
LogBufferElement *e = *it;
if (monotonic) {
if (!android::isMonotonic(e->mRealTime)) {
LogKlog::convertRealToMonotonic(e->mRealTime);
}
} else {
if (android::isMonotonic(e->mRealTime)) {
LogKlog::convertMonotonicToReal(e->mRealTime);
}
}
++it;
}
pthread_mutex_unlock(&mLogElementsLock);
}
// We may have been triggered by a SIGHUP. Release any sleeping reader
// threads to dump their current content.
//
// NB: this is _not_ performed in the context of a SIGHUP, it is
// performed during startup, and in context of reinit administrative thread
LogTimeEntry::lock();
LastLogTimes::iterator times = mTimes.begin();
while(times != mTimes.end()) {
LogTimeEntry *entry = (*times);
if (entry->owned_Locked()) {
entry->triggerReader_Locked();
}
times++;
}
LogTimeEntry::unlock();
}
LogBuffer::LogBuffer(LastLogTimes *times):
monotonic(android_log_clockid() == CLOCK_MONOTONIC),
mTimes(*times) {
pthread_mutex_init(&mLogElementsLock, NULL);
init();
}
int LogBuffer::log(log_id_t log_id, log_time realtime,
uid_t uid, pid_t pid, pid_t tid,
const char *msg, unsigned short len) {
if ((log_id >= LOG_ID_MAX) || (log_id < 0)) {
return -EINVAL;
}
LogBufferElement *elem = new LogBufferElement(log_id, realtime,
uid, pid, tid, msg, len);
if (log_id != LOG_ID_SECURITY) {
int prio = ANDROID_LOG_INFO;
const char *tag = NULL;
if (log_id == LOG_ID_EVENTS) {
tag = android::tagToName(elem->getTag());
} else {
prio = *msg;
tag = msg + 1;
}
if (!__android_log_is_loggable(prio, tag, ANDROID_LOG_VERBOSE)) {
// Log traffic received to total
pthread_mutex_lock(&mLogElementsLock);
stats.add(elem);
stats.subtract(elem);
pthread_mutex_unlock(&mLogElementsLock);
delete elem;
return -EACCES;
}
}
pthread_mutex_lock(&mLogElementsLock);
// Insert elements in time sorted order if possible
// NB: if end is region locked, place element at end of list
LogBufferElementCollection::iterator it = mLogElements.end();
LogBufferElementCollection::iterator last = it;
while (last != mLogElements.begin()) {
--it;
if ((*it)->getRealTime() <= realtime) {
break;
}
last = it;
}
if (last == mLogElements.end()) {
mLogElements.push_back(elem);
} else {
uint64_t end = 1;
bool end_set = false;
bool end_always = false;
LogTimeEntry::lock();
LastLogTimes::iterator t = mTimes.begin();
while(t != mTimes.end()) {
LogTimeEntry *entry = (*t);
if (entry->owned_Locked()) {
if (!entry->mNonBlock) {
end_always = true;
break;
}
if (!end_set || (end <= entry->mEnd)) {
end = entry->mEnd;
end_set = true;
}
}
t++;
}
if (end_always
|| (end_set && (end >= (*last)->getSequence()))) {
mLogElements.push_back(elem);
} else {
mLogElements.insert(last,elem);
}
LogTimeEntry::unlock();
}
stats.add(elem);
maybePrune(log_id);
pthread_mutex_unlock(&mLogElementsLock);
return len;
}
// Prune at most 10% of the log entries or maxPrune, whichever is less.
//
// mLogElementsLock must be held when this function is called.
void LogBuffer::maybePrune(log_id_t id) {
size_t sizes = stats.sizes(id);
unsigned long maxSize = log_buffer_size(id);
if (sizes > maxSize) {
size_t sizeOver = sizes - ((maxSize * 9) / 10);
size_t elements = stats.realElements(id);
size_t minElements = elements / 100;
if (minElements < minPrune) {
minElements = minPrune;
}
unsigned long pruneRows = elements * sizeOver / sizes;
if (pruneRows < minElements) {
pruneRows = minElements;
}
if (pruneRows > maxPrune) {
pruneRows = maxPrune;
}
prune(id, pruneRows);
}
}
LogBufferElementCollection::iterator LogBuffer::erase(
LogBufferElementCollection::iterator it, bool coalesce) {
LogBufferElement *e = *it;
log_id_t id = e->getLogId();
LogBufferIteratorMap::iterator f = mLastWorstUid[id].find(e->getUid());
if ((f != mLastWorstUid[id].end()) && (it == f->second)) {
mLastWorstUid[id].erase(f);
}
it = mLogElements.erase(it);
if (coalesce) {
stats.erase(e);
} else {
stats.subtract(e);
}
delete e;
return it;
}
// Define a temporary mechanism to report the last LogBufferElement pointer
// for the specified uid, pid and tid. Used below to help merge-sort when
// pruning for worst UID.
class LogBufferElementKey {
const union {
struct {
uint16_t uid;
uint16_t pid;
uint16_t tid;
uint16_t padding;
} __packed;
uint64_t value;
} __packed;
public:
LogBufferElementKey(uid_t u, pid_t p, pid_t t):uid(u),pid(p),tid(t),padding(0) { }
LogBufferElementKey(uint64_t k):value(k) { }
uint64_t getKey() { return value; }
};
class LogBufferElementLast {
typedef std::unordered_map<uint64_t, LogBufferElement *> LogBufferElementMap;
LogBufferElementMap map;
public:
bool coalesce(LogBufferElement *e, unsigned short dropped) {
LogBufferElementKey key(e->getUid(), e->getPid(), e->getTid());
LogBufferElementMap::iterator it = map.find(key.getKey());
if (it != map.end()) {
LogBufferElement *l = it->second;
unsigned short d = l->getDropped();
if ((dropped + d) > USHRT_MAX) {
map.erase(it);
} else {
l->setDropped(dropped + d);
return true;
}
}
return false;
}
void add(LogBufferElement *e) {
LogBufferElementKey key(e->getUid(), e->getPid(), e->getTid());
map[key.getKey()] = e;
}
inline void clear() {
map.clear();
}
void clear(LogBufferElement *e) {
uint64_t current = e->getRealTime().nsec()
- (EXPIRE_RATELIMIT * NS_PER_SEC);
for(LogBufferElementMap::iterator it = map.begin(); it != map.end();) {
LogBufferElement *l = it->second;
if ((l->getDropped() >= EXPIRE_THRESHOLD)
&& (current > l->getRealTime().nsec())) {
it = map.erase(it);
} else {
++it;
}
}
}
};
// prune "pruneRows" of type "id" from the buffer.
//
// This garbage collection task is used to expire log entries. It is called to
// remove all logs (clear), all UID logs (unprivileged clear), or every
// 256 or 10% of the total logs (whichever is less) to prune the logs.
//
// First there is a prep phase where we discover the reader region lock that
// acts as a backstop to any pruning activity to stop there and go no further.
//
// There are three major pruning loops that follow. All expire from the oldest
// entries. Since there are multiple log buffers, the Android logging facility
// will appear to drop entries 'in the middle' when looking at multiple log
// sources and buffers. This effect is slightly more prominent when we prune
// the worst offender by logging source. Thus the logs slowly loose content
// and value as you move back in time. This is preferred since chatty sources
// invariably move the logs value down faster as less chatty sources would be
// expired in the noise.
//
// The first loop performs blacklisting and worst offender pruning. Falling
// through when there are no notable worst offenders and have not hit the
// region lock preventing further worst offender pruning. This loop also looks
// after managing the chatty log entries and merging to help provide
// statistical basis for blame. The chatty entries are not a notification of
// how much logs you may have, but instead represent how much logs you would
// have had in a virtual log buffer that is extended to cover all the in-memory
// logs without loss. They last much longer than the represented pruned logs
// since they get multiplied by the gains in the non-chatty log sources.
//
// The second loop get complicated because an algorithm of watermarks and
// history is maintained to reduce the order and keep processing time
// down to a minimum at scale. These algorithms can be costly in the face
// of larger log buffers, or severly limited processing time granted to a
// background task at lowest priority.
//
// This second loop does straight-up expiration from the end of the logs
// (again, remember for the specified log buffer id) but does some whitelist
// preservation. Thus whitelist is a Hail Mary low priority, blacklists and
// spam filtration all take priority. This second loop also checks if a region
// lock is causing us to buffer too much in the logs to help the reader(s),
// and will tell the slowest reader thread to skip log entries, and if
// persistent and hits a further threshold, kill the reader thread.
//
// The third thread is optional, and only gets hit if there was a whitelist
// and more needs to be pruned against the backstop of the region lock.
//
// mLogElementsLock must be held when this function is called.
//
bool LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) {
LogTimeEntry *oldest = NULL;
bool busy = false;
bool clearAll = pruneRows == ULONG_MAX;
LogTimeEntry::lock();
// Region locked?
LastLogTimes::iterator t = mTimes.begin();
while(t != mTimes.end()) {
LogTimeEntry *entry = (*t);
if (entry->owned_Locked() && entry->isWatching(id)
&& (!oldest ||
(oldest->mStart > entry->mStart) ||
((oldest->mStart == entry->mStart) &&
(entry->mTimeout.tv_sec || entry->mTimeout.tv_nsec)))) {
oldest = entry;
}
t++;
}
LogBufferElementCollection::iterator it;
if (caller_uid != AID_ROOT) {
// Only here if clearAll condition (pruneRows == ULONG_MAX)
for(it = mLogElements.begin(); it != mLogElements.end();) {
LogBufferElement *e = *it;
if ((e->getLogId() != id) || (e->getUid() != caller_uid)) {
++it;
continue;
}
if (oldest && (oldest->mStart <= e->getSequence())) {
busy = true;
if (oldest->mTimeout.tv_sec || oldest->mTimeout.tv_nsec) {
oldest->triggerReader_Locked();
} else {
oldest->triggerSkip_Locked(id, pruneRows);
}
break;
}
it = erase(it);
pruneRows--;
}
LogTimeEntry::unlock();
return busy;
}
// prune by worst offender by uid
bool hasBlacklist = (id != LOG_ID_SECURITY) && mPrune.naughty();
while (!clearAll && (pruneRows > 0)) {
// recalculate the worst offender on every batched pass
uid_t worst = (uid_t) -1;
size_t worst_sizes = 0;
size_t second_worst_sizes = 0;
if (worstUidEnabledForLogid(id) && mPrune.worstUidEnabled()) {
std::unique_ptr<const UidEntry *[]> sorted = stats.sort(
AID_ROOT, (pid_t)0, 2, id);
if (sorted.get()) {
if (sorted[0] && sorted[1]) {
worst_sizes = sorted[0]->getSizes();
// Calculate threshold as 12.5% of available storage
size_t threshold = log_buffer_size(id) / 8;
if ((worst_sizes > threshold)
// Allow time horizon to extend roughly tenfold, assume
// average entry length is 100 characters.
&& (worst_sizes > (10 * sorted[0]->getDropped()))) {
worst = sorted[0]->getKey();
second_worst_sizes = sorted[1]->getSizes();
if (second_worst_sizes < threshold) {
second_worst_sizes = threshold;
}
}
}
}
}
// skip if we have neither worst nor naughty filters
if ((worst == (uid_t) -1) && !hasBlacklist) {
break;
}
bool kick = false;
bool leading = true;
it = mLogElements.begin();
// Perform at least one mandatory garbage collection cycle in following
// - clear leading chatty tags
// - coalesce chatty tags
// - check age-out of preserved logs
bool gc = pruneRows <= 1;
if (!gc && (worst != (uid_t) -1)) {
LogBufferIteratorMap::iterator f = mLastWorstUid[id].find(worst);
if ((f != mLastWorstUid[id].end())
&& (f->second != mLogElements.end())) {
leading = false;
it = f->second;
}
}
static const timespec too_old = {
EXPIRE_HOUR_THRESHOLD * 60 * 60, 0
};
LogBufferElementCollection::iterator lastt;
lastt = mLogElements.end();
--lastt;
LogBufferElementLast last;
while (it != mLogElements.end()) {
LogBufferElement *e = *it;
if (oldest && (oldest->mStart <= e->getSequence())) {
busy = true;
if (oldest->mTimeout.tv_sec || oldest->mTimeout.tv_nsec) {
oldest->triggerReader_Locked();
}
break;
}
if (e->getLogId() != id) {
++it;
continue;
}
unsigned short dropped = e->getDropped();
// remove any leading drops
if (leading && dropped) {
it = erase(it);
continue;
}
if (dropped && last.coalesce(e, dropped)) {
it = erase(it, true);
continue;
}
if (hasBlacklist && mPrune.naughty(e)) {
last.clear(e);
it = erase(it);
if (dropped) {
continue;
}
pruneRows--;
if (pruneRows == 0) {
break;
}
if (e->getUid() == worst) {
kick = true;
if (worst_sizes < second_worst_sizes) {
break;
}
worst_sizes -= e->getMsgLen();
}
continue;
}
if ((e->getRealTime() < ((*lastt)->getRealTime() - too_old))
|| (e->getRealTime() > (*lastt)->getRealTime())) {
break;
}
if (dropped) {
last.add(e);
if ((!gc && (e->getUid() == worst))
|| (mLastWorstUid[id].find(e->getUid())
== mLastWorstUid[id].end())) {
mLastWorstUid[id][e->getUid()] = it;
}
++it;
continue;
}
if (e->getUid() != worst) {
leading = false;
last.clear(e);
++it;
continue;
}
pruneRows--;
if (pruneRows == 0) {
break;
}
kick = true;
unsigned short len = e->getMsgLen();
// do not create any leading drops
if (leading) {
it = erase(it);
} else {
stats.drop(e);
e->setDropped(1);
if (last.coalesce(e, 1)) {
it = erase(it, true);
} else {
last.add(e);
if (!gc || (mLastWorstUid[id].find(worst)
== mLastWorstUid[id].end())) {
mLastWorstUid[id][worst] = it;
}
++it;
}
}
if (worst_sizes < second_worst_sizes) {
break;
}
worst_sizes -= len;
}
last.clear();
if (!kick || !mPrune.worstUidEnabled()) {
break; // the following loop will ask bad clients to skip/drop
}
}
bool whitelist = false;
bool hasWhitelist = (id != LOG_ID_SECURITY) && mPrune.nice() && !clearAll;
it = mLogElements.begin();
while((pruneRows > 0) && (it != mLogElements.end())) {
LogBufferElement *e = *it;
if (e->getLogId() != id) {
it++;
continue;
}
if (oldest && (oldest->mStart <= e->getSequence())) {
busy = true;
if (whitelist) {
break;
}
if (stats.sizes(id) > (2 * log_buffer_size(id))) {
// kick a misbehaving log reader client off the island
oldest->release_Locked();
} else if (oldest->mTimeout.tv_sec || oldest->mTimeout.tv_nsec) {
oldest->triggerReader_Locked();
} else {
oldest->triggerSkip_Locked(id, pruneRows);
}
break;
}
if (hasWhitelist && !e->getDropped() && mPrune.nice(e)) { // WhiteListed
whitelist = true;
it++;
continue;
}
it = erase(it);
pruneRows--;
}
// Do not save the whitelist if we are reader range limited
if (whitelist && (pruneRows > 0)) {
it = mLogElements.begin();
while((it != mLogElements.end()) && (pruneRows > 0)) {
LogBufferElement *e = *it;
if (e->getLogId() != id) {
++it;
continue;
}
if (oldest && (oldest->mStart <= e->getSequence())) {
busy = true;
if (stats.sizes(id) > (2 * log_buffer_size(id))) {
// kick a misbehaving log reader client off the island
oldest->release_Locked();
} else if (oldest->mTimeout.tv_sec || oldest->mTimeout.tv_nsec) {
oldest->triggerReader_Locked();
} else {
oldest->triggerSkip_Locked(id, pruneRows);
}
break;
}
it = erase(it);
pruneRows--;
}
}
LogTimeEntry::unlock();
return (pruneRows > 0) && busy;
}
// clear all rows of type "id" from the buffer.
bool LogBuffer::clear(log_id_t id, uid_t uid) {
bool busy = true;
// If it takes more than 4 tries (seconds) to clear, then kill reader(s)
for (int retry = 4;;) {
if (retry == 1) { // last pass
// Check if it is still busy after the sleep, we say prune
// one entry, not another clear run, so we are looking for
// the quick side effect of the return value to tell us if
// we have a _blocked_ reader.
pthread_mutex_lock(&mLogElementsLock);
busy = prune(id, 1, uid);
pthread_mutex_unlock(&mLogElementsLock);
// It is still busy, blocked reader(s), lets kill them all!
// otherwise, lets be a good citizen and preserve the slow
// readers and let the clear run (below) deal with determining
// if we are still blocked and return an error code to caller.
if (busy) {
LogTimeEntry::lock();
LastLogTimes::iterator times = mTimes.begin();
while (times != mTimes.end()) {
LogTimeEntry *entry = (*times);
// Killer punch
if (entry->owned_Locked() && entry->isWatching(id)) {
entry->release_Locked();
}
times++;
}
LogTimeEntry::unlock();
}
}
pthread_mutex_lock(&mLogElementsLock);
busy = prune(id, ULONG_MAX, uid);
pthread_mutex_unlock(&mLogElementsLock);
if (!busy || !--retry) {
break;
}
sleep (1); // Let reader(s) catch up after notification
}
return busy;
}
// get the used space associated with "id".
unsigned long LogBuffer::getSizeUsed(log_id_t id) {
pthread_mutex_lock(&mLogElementsLock);
size_t retval = stats.sizes(id);
pthread_mutex_unlock(&mLogElementsLock);
return retval;
}
// set the total space allocated to "id"
int LogBuffer::setSize(log_id_t id, unsigned long size) {
// Reasonable limits ...
if (!valid_size(size)) {
return -1;
}
pthread_mutex_lock(&mLogElementsLock);
log_buffer_size(id) = size;
pthread_mutex_unlock(&mLogElementsLock);
return 0;
}
// get the total space allocated to "id"
unsigned long LogBuffer::getSize(log_id_t id) {
pthread_mutex_lock(&mLogElementsLock);
size_t retval = log_buffer_size(id);
pthread_mutex_unlock(&mLogElementsLock);
return retval;
}
uint64_t LogBuffer::flushTo(
SocketClient *reader, const uint64_t start, bool privileged,
int (*filter)(const LogBufferElement *element, void *arg), void *arg) {
LogBufferElementCollection::iterator it;
uint64_t max = start;
uid_t uid = reader->getUid();
pthread_mutex_lock(&mLogElementsLock);
if (start <= 1) {
// client wants to start from the beginning
it = mLogElements.begin();
} else {
// Client wants to start from some specified time. Chances are
// we are better off starting from the end of the time sorted list.
for (it = mLogElements.end(); it != mLogElements.begin(); /* do nothing */) {
--it;
LogBufferElement *element = *it;
if (element->getSequence() <= start) {
it++;
break;
}
}
}
for (; it != mLogElements.end(); ++it) {
LogBufferElement *element = *it;
if (!privileged && (element->getUid() != uid)) {
continue;
}
if (element->getSequence() <= start) {
continue;
}
// NB: calling out to another object with mLogElementsLock held (safe)
if (filter) {
int ret = (*filter)(element, arg);
if (ret == false) {
continue;
}
if (ret != true) {
break;
}
}
pthread_mutex_unlock(&mLogElementsLock);
// range locking in LastLogTimes looks after us
max = element->flushTo(reader, this, privileged);
if (max == element->FLUSH_ERROR) {
return max;
}
pthread_mutex_lock(&mLogElementsLock);
}
pthread_mutex_unlock(&mLogElementsLock);
return max;
}
std::string LogBuffer::formatStatistics(uid_t uid, pid_t pid,
unsigned int logMask) {
pthread_mutex_lock(&mLogElementsLock);
std::string ret = stats.format(uid, pid, logMask);
pthread_mutex_unlock(&mLogElementsLock);
return ret;
}
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