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platform_system_core/logd/LogBuffer.cpp
Mark Salyzyn 206ed8e2d6 logd: remove start filtration from flushTo (part deux) 
We have already searched for the start point, the start filter check
is paranoia that removes out-of-order entries that we are undoubtably
interested in.  Out-of-order entries occur under reader pressure, as
the writer gets pushed back from in-place sorted order and lands it
at the end for the reader to pick it up.  If this occurred during a
batch run or a logger thread wakeup, the entry could be filtered out
and never output to the reader.

We have to treat exact finds for start in the list as terminal when
we search as they represent restarts, depending on the fact that it
is impossible to have the exact same time reported in two log entries
or requested from a batched reader.  This does break down if a log
entry has xxxxxx000 nanoseconds reported, we fix that by making sure
we never log such a case and slip it by a ns.

Found one case where logcat.tail_time* tests failed which was fixed
with this adjustment.

Test: gTest logd-unit-tests, liblog-unit-tests and logcat-unit-tests
Bug: 38046067
Bug: 37791296
Bug: 38341453
Change-Id: I4dd2e2596dd67b8d602160dd79661e01805227a9
2017-05-19 07:15:38 -07:00

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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.
*/
// for manual checking of stale entries during LogBuffer::erase()
//#define DEBUG_CHECK_FOR_STALE_ENTRIES
#include <ctype.h>
#include <endian.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <sys/cdefs.h>
#include <sys/user.h>
#include <time.h>
#include <unistd.h>
#include <unordered_map>
#include <cutils/properties.h>
#include <private/android_logger.h>
#include "LogBuffer.h"
#include "LogKlog.h"
#include "LogReader.h"
#include "LogUtils.h"
#ifndef __predict_false
#define __predict_false(exp) __builtin_expect((exp) != 0, 0)
#endif
// Default
#define log_buffer_size(id) mMaxSize[id]
const log_time LogBuffer::pruneMargin(3, 0);
void LogBuffer::init() {
log_id_for_each(i) {
mLastSet[i] = false;
mLast[i] = mLogElements.begin();
if (setSize(i, __android_logger_get_buffer_size(i))) {
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.
//
rdlock();
LogBufferElementCollection::iterator it = mLogElements.begin();
while ((it != mLogElements.end())) {
LogBufferElement* e = *it;
if (monotonic) {
if (!android::isMonotonic(e->mRealTime)) {
LogKlog::convertRealToMonotonic(e->mRealTime);
if ((e->mRealTime.tv_nsec % 1000) == 0) {
e->mRealTime.tv_nsec++;
}
}
} else {
if (android::isMonotonic(e->mRealTime)) {
LogKlog::convertMonotonicToReal(e->mRealTime);
if ((e->mRealTime.tv_nsec % 1000) == 0) {
e->mRealTime.tv_nsec++;
}
}
}
++it;
}
unlock();
}
// 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::wrlock();
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_rwlock_init(&mLogElementsLock, nullptr);
log_id_for_each(i) {
lastLoggedElements[i] = nullptr;
droppedElements[i] = nullptr;
}
init();
}
LogBuffer::~LogBuffer() {
log_id_for_each(i) {
delete lastLoggedElements[i];
delete droppedElements[i];
}
}
enum match_type { DIFFERENT, SAME, SAME_LIBLOG };
static enum match_type identical(LogBufferElement* elem,
LogBufferElement* last) {
// is it mostly identical?
// if (!elem) return DIFFERENT;
ssize_t lenl = elem->getMsgLen();
if (lenl <= 0) return DIFFERENT; // value if this represents a chatty elem
// if (!last) return DIFFERENT;
ssize_t lenr = last->getMsgLen();
if (lenr <= 0) return DIFFERENT; // value if this represents a chatty elem
// if (elem->getLogId() != last->getLogId()) return DIFFERENT;
if (elem->getUid() != last->getUid()) return DIFFERENT;
if (elem->getPid() != last->getPid()) return DIFFERENT;
if (elem->getTid() != last->getTid()) return DIFFERENT;
// last is more than a minute old, stop squashing identical messages
if (elem->getRealTime().nsec() >
(last->getRealTime().nsec() + 60 * NS_PER_SEC))
return DIFFERENT;
// Identical message
const char* msgl = elem->getMsg();
const char* msgr = last->getMsg();
if (lenl == lenr) {
if (!fastcmp<memcmp>(msgl, msgr, lenl)) return SAME;
// liblog tagged messages (content gets summed)
if ((elem->getLogId() == LOG_ID_EVENTS) &&
(lenl == sizeof(android_log_event_int_t)) &&
!fastcmp<memcmp>(msgl, msgr, sizeof(android_log_event_int_t) -
sizeof(int32_t)) &&
(elem->getTag() == LIBLOG_LOG_TAG))
return SAME_LIBLOG;
}
// audit message (except sequence number) identical?
if (last->isBinary()) {
if (fastcmp<memcmp>(msgl, msgr, sizeof(android_log_event_string_t) -
sizeof(int32_t)))
return DIFFERENT;
msgl += sizeof(android_log_event_string_t);
lenl -= sizeof(android_log_event_string_t);
msgr += sizeof(android_log_event_string_t);
lenr -= sizeof(android_log_event_string_t);
}
static const char avc[] = "): avc: ";
const char* avcl = android::strnstr(msgl, lenl, avc);
if (!avcl) return DIFFERENT;
lenl -= avcl - msgl;
const char* avcr = android::strnstr(msgr, lenr, avc);
if (!avcr) return DIFFERENT;
lenr -= avcr - msgr;
if (lenl != lenr) return DIFFERENT;
if (fastcmp<memcmp>(avcl + strlen(avc), avcr + strlen(avc),
lenl - strlen(avc))) {
return DIFFERENT;
}
return SAME;
}
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;
}
// Slip the time by 1 nsec if the incoming lands on xxxxxx000 ns.
// This prevents any chance that an outside source can request an
// exact entry with time specified in ms or us precision.
if ((realtime.tv_nsec % 1000) == 0) ++realtime.tv_nsec;
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 = nullptr;
if (log_id == LOG_ID_EVENTS) {
tag = tagToName(elem->getTag());
} else {
prio = *msg;
tag = msg + 1;
}
if (!__android_log_is_loggable(prio, tag, ANDROID_LOG_VERBOSE)) {
// Log traffic received to total
wrlock();
stats.addTotal(elem);
unlock();
delete elem;
return -EACCES;
}
}
wrlock();
LogBufferElement* currentLast = lastLoggedElements[log_id];
if (currentLast) {
LogBufferElement* dropped = droppedElements[log_id];
unsigned short count = dropped ? dropped->getDropped() : 0;
//
// State Init
// incoming:
// dropped = nullptr
// currentLast = nullptr;
// elem = incoming message
// outgoing:
// dropped = nullptr -> State 0
// currentLast = copy of elem
// log elem
// State 0
// incoming:
// count = 0
// dropped = nullptr
// currentLast = copy of last message
// elem = incoming message
// outgoing: if match != DIFFERENT
// dropped = copy of first identical message -> State 1
// currentLast = reference to elem
// break: if match == DIFFERENT
// dropped = nullptr -> State 0
// delete copy of last message (incoming currentLast)
// currentLast = copy of elem
// log elem
// State 1
// incoming:
// count = 0
// dropped = copy of first identical message
// currentLast = reference to last held-back incoming
// message
// elem = incoming message
// outgoing: if match == SAME
// delete copy of first identical message (dropped)
// dropped = reference to last held-back incoming
// message set to chatty count of 1 -> State 2
// currentLast = reference to elem
// outgoing: if match == SAME_LIBLOG
// dropped = copy of first identical message -> State 1
// take sum of currentLast and elem
// if sum overflows:
// log currentLast
// currentLast = reference to elem
// else
// delete currentLast
// currentLast = reference to elem, sum liblog.
// break: if match == DIFFERENT
// delete dropped
// dropped = nullptr -> State 0
// log reference to last held-back (currentLast)
// currentLast = copy of elem
// log elem
// State 2
// incoming:
// count = chatty count
// dropped = chatty message holding count
// currentLast = reference to last held-back incoming
// message.
// dropped = chatty message holding count
// elem = incoming message
// outgoing: if match != DIFFERENT
// delete chatty message holding count
// dropped = reference to last held-back incoming
// message, set to chatty count + 1
// currentLast = reference to elem
// break: if match == DIFFERENT
// log dropped (chatty message)
// dropped = nullptr -> State 0
// log reference to last held-back (currentLast)
// currentLast = copy of elem
// log elem
//
enum match_type match = identical(elem, currentLast);
if (match != DIFFERENT) {
if (dropped) {
// Sum up liblog tag messages?
if ((count == 0) /* at Pass 1 */ && (match == SAME_LIBLOG)) {
android_log_event_int_t* event =
reinterpret_cast<android_log_event_int_t*>(
const_cast<char*>(currentLast->getMsg()));
//
// To unit test, differentiate with something like:
// event->header.tag = htole32(CHATTY_LOG_TAG);
// here, then instead of delete currentLast below,
// log(currentLast) to see the incremental sums form.
//
uint32_t swab = event->payload.data;
unsigned long long total = htole32(swab);
event = reinterpret_cast<android_log_event_int_t*>(
const_cast<char*>(elem->getMsg()));
swab = event->payload.data;
lastLoggedElements[LOG_ID_EVENTS] = elem;
total += htole32(swab);
// check for overflow
if (total >= UINT32_MAX) {
log(currentLast);
unlock();
return len;
}
stats.addTotal(currentLast);
delete currentLast;
swab = total;
event->payload.data = htole32(swab);
unlock();
return len;
}
if (count == USHRT_MAX) {
log(dropped);
count = 1;
} else {
delete dropped;
++count;
}
}
if (count) {
stats.addTotal(currentLast);
currentLast->setDropped(count);
}
droppedElements[log_id] = currentLast;
lastLoggedElements[log_id] = elem;
unlock();
return len;
}
if (dropped) { // State 1 or 2
if (count) { // State 2
log(dropped); // report chatty
} else { // State 1
delete dropped;
}
droppedElements[log_id] = nullptr;
log(currentLast); // report last message in the series
} else { // State 0
delete currentLast;
}
}
lastLoggedElements[log_id] = new LogBufferElement(*elem);
log(elem);
unlock();
return len;
}
// assumes LogBuffer::wrlock() held, owns elem, look after garbage collection
void LogBuffer::log(LogBufferElement* elem) {
// cap on how far back we will sort in-place, otherwise append
static uint32_t too_far_back = 5; // five seconds
// 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;
if (__predict_true(it != mLogElements.begin())) --it;
if (__predict_false(it == mLogElements.begin()) ||
__predict_true((*it)->getRealTime() <= elem->getRealTime()) ||
__predict_false((((*it)->getRealTime().tv_sec - too_far_back) >
elem->getRealTime().tv_sec) &&
(elem->getLogId() != LOG_ID_KERNEL) &&
((*it)->getLogId() != LOG_ID_KERNEL))) {
mLogElements.push_back(elem);
} else {
log_time end = log_time::EPOCH;
bool end_set = false;
bool end_always = false;
LogTimeEntry::rdlock();
LastLogTimes::iterator times = mTimes.begin();
while (times != mTimes.end()) {
LogTimeEntry* entry = (*times);
if (entry->owned_Locked()) {
if (!entry->mNonBlock) {
end_always = true;
break;
}
// it passing mEnd is blocked by the following checks.
if (!end_set || (end <= entry->mEnd)) {
end = entry->mEnd;
end_set = true;
}
}
times++;
}
if (end_always || (end_set && (end > (*it)->getRealTime()))) {
mLogElements.push_back(elem);
} else {
// should be short as timestamps are localized near end()
do {
last = it;
if (__predict_false(it == mLogElements.begin())) {
break;
}
--it;
} while (((*it)->getRealTime() > elem->getRealTime()) &&
(!end_set || (end <= (*it)->getRealTime())));
mLogElements.insert(last, elem);
}
LogTimeEntry::unlock();
}
stats.add(elem);
maybePrune(elem->getLogId());
}
// Prune at most 10% of the log entries or maxPrune, whichever is less.
//
// LogBuffer::wrlock() 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* element = *it;
log_id_t id = element->getLogId();
// Remove iterator references in the various lists that will become stale
// after the element is erased from the main logging list.
{ // start of scope for found iterator
int key = ((id == LOG_ID_EVENTS) || (id == LOG_ID_SECURITY))
? element->getTag()
: element->getUid();
LogBufferIteratorMap::iterator found = mLastWorst[id].find(key);
if ((found != mLastWorst[id].end()) && (it == found->second)) {
mLastWorst[id].erase(found);
}
}
{ // start of scope for pid found iterator
// element->getUid() may not be AID_SYSTEM for next-best-watermark.
// will not assume id != LOG_ID_EVENTS or LOG_ID_SECURITY for KISS and
// long term code stability, find() check should be fast for those ids.
LogBufferPidIteratorMap::iterator found =
mLastWorstPidOfSystem[id].find(element->getPid());
if ((found != mLastWorstPidOfSystem[id].end()) &&
(it == found->second)) {
mLastWorstPidOfSystem[id].erase(found);
}
}
bool setLast[LOG_ID_MAX];
bool doSetLast = false;
log_id_for_each(i) {
doSetLast |= setLast[i] = mLastSet[i] && (it == mLast[i]);
}
#ifdef DEBUG_CHECK_FOR_STALE_ENTRIES
LogBufferElementCollection::iterator bad = it;
int key = ((id == LOG_ID_EVENTS) || (id == LOG_ID_SECURITY))
? element->getTag()
: element->getUid();
#endif
it = mLogElements.erase(it);
if (doSetLast) {
log_id_for_each(i) {
if (setLast[i]) {
if (__predict_false(it == mLogElements.end())) { // impossible
mLastSet[i] = false;
mLast[i] = mLogElements.begin();
} else {
mLast[i] = it; // push down the road as next-best-watermark
}
}
}
}
#ifdef DEBUG_CHECK_FOR_STALE_ENTRIES
log_id_for_each(i) {
for (auto b : mLastWorst[i]) {
if (bad == b.second) {
android::prdebug("stale mLastWorst[%d] key=%d mykey=%d\n", i,
b.first, key);
}
}
for (auto b : mLastWorstPidOfSystem[i]) {
if (bad == b.second) {
android::prdebug("stale mLastWorstPidOfSystem[%d] pid=%d\n", i,
b.first);
}
}
if (mLastSet[i] && (bad == mLast[i])) {
android::prdebug("stale mLast[%d]\n", i);
mLastSet[i] = false;
mLast[i] = mLogElements.begin();
}
}
#endif
if (coalesce) {
stats.erase(element);
} else {
stats.subtract(element);
}
delete element;
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 {
uint32_t uid;
uint16_t pid;
uint16_t tid;
} __packed;
uint64_t value;
} __packed;
public:
LogBufferElementKey(uid_t uid, pid_t pid, pid_t tid)
: uid(uid), pid(pid), tid(tid) {
}
explicit LogBufferElementKey(uint64_t key) : value(key) {
}
uint64_t getKey() {
return value;
}
};
class LogBufferElementLast {
typedef std::unordered_map<uint64_t, LogBufferElement*> LogBufferElementMap;
LogBufferElementMap map;
public:
bool coalesce(LogBufferElement* element, unsigned short dropped) {
LogBufferElementKey key(element->getUid(), element->getPid(),
element->getTid());
LogBufferElementMap::iterator it = map.find(key.getKey());
if (it != map.end()) {
LogBufferElement* found = it->second;
unsigned short moreDropped = found->getDropped();
if ((dropped + moreDropped) > USHRT_MAX) {
map.erase(it);
} else {
found->setDropped(dropped + moreDropped);
return true;
}
}
return false;
}
void add(LogBufferElement* element) {
LogBufferElementKey key(element->getUid(), element->getPid(),
element->getTid());
map[key.getKey()] = element;
}
inline void clear() {
map.clear();
}
void clear(LogBufferElement* element) {
log_time current =
element->getRealTime() - log_time(EXPIRE_RATELIMIT, 0);
for (LogBufferElementMap::iterator it = map.begin(); it != map.end();) {
LogBufferElement* mapElement = it->second;
if ((mapElement->getDropped() >= EXPIRE_THRESHOLD) &&
(current > mapElement->getRealTime())) {
it = map.erase(it);
} else {
++it;
}
}
}
};
// Determine if watermark is within pruneMargin + 1s from the end of the list,
// the caller will use this result to set an internal busy flag indicating
// the prune operation could not be completed because a reader is blocking
// the request.
bool LogBuffer::isBusy(log_time watermark) {
LogBufferElementCollection::iterator ei = mLogElements.end();
--ei;
return watermark < ((*ei)->getRealTime() - pruneMargin - log_time(1, 0));
}
// If the selected reader is blocking our pruning progress, decide on
// what kind of mitigation is necessary to unblock the situation.
void LogBuffer::kickMe(LogTimeEntry* me, log_id_t id, unsigned long pruneRows) {
if (stats.sizes(id) > (2 * log_buffer_size(id))) { // +100%
// A misbehaving or slow reader has its connection
// dropped if we hit too much memory pressure.
me->release_Locked();
} else if (me->mTimeout.tv_sec || me->mTimeout.tv_nsec) {
// Allow a blocked WRAP timeout reader to
// trigger and start reporting the log data.
me->triggerReader_Locked();
} else {
// tell slow reader to skip entries to catch up
me->triggerSkip_Locked(id, pruneRows);
}
}
// 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.
//
// LogBuffer::wrlock() must be held when this function is called.
//
bool LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) {
LogTimeEntry* oldest = nullptr;
bool busy = false;
bool clearAll = pruneRows == ULONG_MAX;
LogTimeEntry::rdlock();
// Region locked?
LastLogTimes::iterator times = mTimes.begin();
while (times != mTimes.end()) {
LogTimeEntry* entry = (*times);
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;
}
times++;
}
log_time watermark(log_time::tv_sec_max, log_time::tv_nsec_max);
if (oldest) watermark = oldest->mStart - pruneMargin;
LogBufferElementCollection::iterator it;
if (__predict_false(caller_uid != AID_ROOT)) { // unlikely
// Only here if clear all request from non system source, so chatty
// filter logistics is not required.
it = mLastSet[id] ? mLast[id] : mLogElements.begin();
while (it != mLogElements.end()) {
LogBufferElement* element = *it;
if ((element->getLogId() != id) ||
(element->getUid() != caller_uid)) {
++it;
continue;
}
if (!mLastSet[id] || ((*mLast[id])->getLogId() != id)) {
mLast[id] = it;
mLastSet[id] = true;
}
if (oldest && (watermark <= element->getRealTime())) {
busy = isBusy(watermark);
if (busy) kickMe(oldest, id, pruneRows);
break;
}
it = erase(it);
if (--pruneRows == 0) {
break;
}
}
LogTimeEntry::unlock();
return busy;
}
// prune by worst offenders; by blacklist, UID, and by PID of system UID
bool hasBlacklist = (id != LOG_ID_SECURITY) && mPrune.naughty();
while (!clearAll && (pruneRows > 0)) {
// recalculate the worst offender on every batched pass
int worst = -1; // not valid for getUid() or getKey()
size_t worst_sizes = 0;
size_t second_worst_sizes = 0;
pid_t worstPid = 0; // POSIX guarantees PID != 0
if (worstUidEnabledForLogid(id) && mPrune.worstUidEnabled()) {
// Calculate threshold as 12.5% of available storage
size_t threshold = log_buffer_size(id) / 8;
if ((id == LOG_ID_EVENTS) || (id == LOG_ID_SECURITY)) {
stats.sortTags(AID_ROOT, (pid_t)0, 2, id)
.findWorst(worst, worst_sizes, second_worst_sizes,
threshold);
// per-pid filter for AID_SYSTEM sources is too complex
} else {
stats.sort(AID_ROOT, (pid_t)0, 2, id)
.findWorst(worst, worst_sizes, second_worst_sizes,
threshold);
if ((worst == AID_SYSTEM) && mPrune.worstPidOfSystemEnabled()) {
stats.sortPids(worst, (pid_t)0, 2, id)
.findWorst(worstPid, worst_sizes, second_worst_sizes);
}
}
}
// skip if we have neither worst nor naughty filters
if ((worst == -1) && !hasBlacklist) {
break;
}
bool kick = false;
bool leading = true;
it = mLastSet[id] ? mLast[id] : 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 != -1)) {
{ // begin scope for worst found iterator
LogBufferIteratorMap::iterator found =
mLastWorst[id].find(worst);
if ((found != mLastWorst[id].end()) &&
(found->second != mLogElements.end())) {
leading = false;
it = found->second;
}
}
if (worstPid) { // begin scope for pid worst found iterator
// FYI: worstPid only set if !LOG_ID_EVENTS and
// !LOG_ID_SECURITY, not going to make that assumption ...
LogBufferPidIteratorMap::iterator found =
mLastWorstPidOfSystem[id].find(worstPid);
if ((found != mLastWorstPidOfSystem[id].end()) &&
(found->second != mLogElements.end())) {
leading = false;
it = found->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* element = *it;
if (oldest && (watermark <= element->getRealTime())) {
busy = isBusy(watermark);
// Do not let chatty eliding trigger any reader mitigation
break;
}
if (element->getLogId() != id) {
++it;
continue;
}
// below this point element->getLogId() == id
if (leading && (!mLastSet[id] || ((*mLast[id])->getLogId() != id))) {
mLast[id] = it;
mLastSet[id] = true;
}
unsigned short dropped = element->getDropped();
// remove any leading drops
if (leading && dropped) {
it = erase(it);
continue;
}
if (dropped && last.coalesce(element, dropped)) {
it = erase(it, true);
continue;
}
int key = ((id == LOG_ID_EVENTS) || (id == LOG_ID_SECURITY))
? element->getTag()
: element->getUid();
if (hasBlacklist && mPrune.naughty(element)) {
last.clear(element);
it = erase(it);
if (dropped) {
continue;
}
pruneRows--;
if (pruneRows == 0) {
break;
}
if (key == worst) {
kick = true;
if (worst_sizes < second_worst_sizes) {
break;
}
worst_sizes -= element->getMsgLen();
}
continue;
}
if ((element->getRealTime() < ((*lastt)->getRealTime() - too_old)) ||
(element->getRealTime() > (*lastt)->getRealTime())) {
break;
}
if (dropped) {
last.add(element);
if (worstPid &&
((!gc && (element->getPid() == worstPid)) ||
(mLastWorstPidOfSystem[id].find(element->getPid()) ==
mLastWorstPidOfSystem[id].end()))) {
// element->getUid() may not be AID_SYSTEM, next best
// watermark if current one empty. id is not LOG_ID_EVENTS
// or LOG_ID_SECURITY because of worstPid check.
mLastWorstPidOfSystem[id][element->getPid()] = it;
}
if ((!gc && !worstPid && (key == worst)) ||
(mLastWorst[id].find(key) == mLastWorst[id].end())) {
mLastWorst[id][key] = it;
}
++it;
continue;
}
if ((key != worst) ||
(worstPid && (element->getPid() != worstPid))) {
leading = false;
last.clear(element);
++it;
continue;
}
// key == worst below here
// If worstPid set, then element->getPid() == worstPid below here
pruneRows--;
if (pruneRows == 0) {
break;
}
kick = true;
unsigned short len = element->getMsgLen();
// do not create any leading drops
if (leading) {
it = erase(it);
} else {
stats.drop(element);
element->setDropped(1);
if (last.coalesce(element, 1)) {
it = erase(it, true);
} else {
last.add(element);
if (worstPid &&
(!gc || (mLastWorstPidOfSystem[id].find(worstPid) ==
mLastWorstPidOfSystem[id].end()))) {
// element->getUid() may not be AID_SYSTEM, next best
// watermark if current one empty. id is not
// LOG_ID_EVENTS or LOG_ID_SECURITY because of worstPid.
mLastWorstPidOfSystem[id][worstPid] = it;
}
if ((!gc && !worstPid) ||
(mLastWorst[id].find(worst) == mLastWorst[id].end())) {
mLastWorst[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 = mLastSet[id] ? mLast[id] : mLogElements.begin();
while ((pruneRows > 0) && (it != mLogElements.end())) {
LogBufferElement* element = *it;
if (element->getLogId() != id) {
it++;
continue;
}
if (!mLastSet[id] || ((*mLast[id])->getLogId() != id)) {
mLast[id] = it;
mLastSet[id] = true;
}
if (oldest && (watermark <= element->getRealTime())) {
busy = isBusy(watermark);
if (!whitelist && busy) kickMe(oldest, id, pruneRows);
break;
}
if (hasWhitelist && !element->getDropped() && mPrune.nice(element)) {
// 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 = mLastSet[id] ? mLast[id] : mLogElements.begin();
while ((it != mLogElements.end()) && (pruneRows > 0)) {
LogBufferElement* element = *it;
if (element->getLogId() != id) {
++it;
continue;
}
if (!mLastSet[id] || ((*mLast[id])->getLogId() != id)) {
mLast[id] = it;
mLastSet[id] = true;
}
if (oldest && (watermark <= element->getRealTime())) {
busy = isBusy(watermark);
if (busy) kickMe(oldest, 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.
wrlock();
busy = prune(id, 1, uid);
unlock();
// 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::wrlock();
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();
}
}
wrlock();
busy = prune(id, ULONG_MAX, uid);
unlock();
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) {
rdlock();
size_t retval = stats.sizes(id);
unlock();
return retval;
}
// set the total space allocated to "id"
int LogBuffer::setSize(log_id_t id, unsigned long size) {
// Reasonable limits ...
if (!__android_logger_valid_buffer_size(size)) {
return -1;
}
wrlock();
log_buffer_size(id) = size;
unlock();
return 0;
}
// get the total space allocated to "id"
unsigned long LogBuffer::getSize(log_id_t id) {
rdlock();
size_t retval = log_buffer_size(id);
unlock();
return retval;
}
log_time LogBuffer::flushTo(SocketClient* reader, const log_time& start,
pid_t* lastTid, bool privileged, bool security,
int (*filter)(const LogBufferElement* element,
void* arg),
void* arg) {
LogBufferElementCollection::iterator it;
uid_t uid = reader->getUid();
rdlock();
if (start == log_time::EPOCH) {
// client wants to start from the beginning
it = mLogElements.begin();
} else {
// 3 second limit to continue search for out-of-order entries.
log_time min = start - pruneMargin;
// Cap to 300 iterations we look back for out-of-order entries.
size_t count = 300;
// Client wants to start from some specified time. Chances are
// we are better off starting from the end of the time sorted list.
LogBufferElementCollection::iterator last;
for (last = it = mLogElements.end(); it != mLogElements.begin();
/* do nothing */) {
--it;
LogBufferElement* element = *it;
if (element->getRealTime() > start) {
last = it;
} else if (element->getRealTime() == start) {
last = ++it;
break;
} else if (!--count || (element->getRealTime() < min)) {
break;
}
}
it = last;
}
log_time curr = start;
LogBufferElement* lastElement = nullptr; // iterator corruption paranoia
static const size_t maxSkip = 4194304; // maximum entries to skip
size_t skip = maxSkip;
for (; it != mLogElements.end(); ++it) {
LogBufferElement* element = *it;
if (!--skip) {
android::prdebug("reader.per: too many elements skipped");
break;
}
if (element == lastElement) {
android::prdebug("reader.per: identical elements");
break;
}
lastElement = element;
if (!privileged && (element->getUid() != uid)) {
continue;
}
if (!security && (element->getLogId() == LOG_ID_SECURITY)) {
continue;
}
// NB: calling out to another object with wrlock() held (safe)
if (filter) {
int ret = (*filter)(element, arg);
if (ret == false) {
continue;
}
if (ret != true) {
break;
}
}
bool sameTid = false;
if (lastTid) {
sameTid = lastTid[element->getLogId()] == element->getTid();
// Dropped (chatty) immediately following a valid log from the
// same source in the same log buffer indicates we have a
// multiple identical squash. chatty that differs source
// is due to spam filter. chatty to chatty of different
// source is also due to spam filter.
lastTid[element->getLogId()] =
(element->getDropped() && !sameTid) ? 0 : element->getTid();
}
unlock();
// range locking in LastLogTimes looks after us
curr = element->flushTo(reader, this, privileged, sameTid);
if (curr == element->FLUSH_ERROR) {
return curr;
}
skip = maxSkip;
rdlock();
}
unlock();
return curr;
}
std::string LogBuffer::formatStatistics(uid_t uid, pid_t pid,
unsigned int logMask) {
wrlock();
std::string ret = stats.format(uid, pid, logMask);
unlock();
return ret;
}
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