Merge changes If6e29418,I6d90838e,Ie488f8ac
* changes:
logd: create SimpleLogBuffer and implement ChattyLogBuffer in terms of it
logd: separate Chatty only vs generic LogBufferTests
logd: move current sequence from LogBufferElement to LogBuffer
diff --git a/logd/Android.bp b/logd/Android.bp
index 5e591d9..1f6ab34 100644
--- a/logd/Android.bp
+++ b/logd/Android.bp
@@ -54,6 +54,7 @@
"LogStatistics.cpp",
"LogWhiteBlackList.cpp",
"LogTags.cpp",
+ "SimpleLogBuffer.cpp",
],
logtags: ["event.logtags"],
@@ -128,6 +129,7 @@
] + event_flag,
srcs: [
+ "ChattyLogBufferTest.cpp",
"logd_test.cpp",
"LogBufferTest.cpp",
],
diff --git a/logd/ChattyLogBuffer.cpp b/logd/ChattyLogBuffer.cpp
index fd2c236..0ba6025 100644
--- a/logd/ChattyLogBuffer.cpp
+++ b/logd/ChattyLogBuffer.cpp
@@ -40,47 +40,15 @@
#define __predict_false(exp) __builtin_expect((exp) != 0, 0)
#endif
-// Default
-#define log_buffer_size(id) mMaxSize[id]
-
-void ChattyLogBuffer::Init() {
- log_id_for_each(i) {
- if (SetSize(i, __android_logger_get_buffer_size(i))) {
- SetSize(i, LOG_BUFFER_MIN_SIZE);
- }
- }
- // Release any sleeping reader threads to dump their current content.
- auto reader_threads_lock = std::lock_guard{reader_list_->reader_threads_lock()};
- for (const auto& reader_thread : reader_list_->reader_threads()) {
- reader_thread->triggerReader_Locked();
- }
-}
-
ChattyLogBuffer::ChattyLogBuffer(LogReaderList* reader_list, LogTags* tags, PruneList* prune,
LogStatistics* stats)
- : reader_list_(reader_list), tags_(tags), prune_(prune), stats_(stats) {
- Init();
-}
+ : SimpleLogBuffer(reader_list, tags, stats), prune_(prune) {}
ChattyLogBuffer::~ChattyLogBuffer() {}
-LogBufferElementCollection::iterator ChattyLogBuffer::GetOldest(log_id_t log_id) {
- auto it = mLogElements.begin();
- if (oldest_[log_id]) {
- it = *oldest_[log_id];
- }
- while (it != mLogElements.end() && it->getLogId() != log_id) {
- it++;
- }
- if (it != mLogElements.end()) {
- oldest_[log_id] = it;
- }
- return it;
-}
-
enum match_type { DIFFERENT, SAME, SAME_LIBLOG };
-static enum match_type identical(LogBufferElement* elem, LogBufferElement* last) {
+static enum match_type Identical(LogBufferElement* elem, LogBufferElement* last) {
// is it mostly identical?
// if (!elem) return DIFFERENT;
ssize_t lenl = elem->getMsgLen();
@@ -135,88 +103,44 @@
return SAME;
}
-bool ChattyLogBuffer::ShouldLog(log_id_t log_id, const char* msg, uint16_t len) {
- if (log_id == LOG_ID_SECURITY) {
- return true;
- }
-
- int prio = ANDROID_LOG_INFO;
- const char* tag = nullptr;
- size_t tag_len = 0;
- if (log_id == LOG_ID_EVENTS || log_id == LOG_ID_STATS) {
- if (len < sizeof(android_event_header_t)) {
- return false;
- }
- int32_t numeric_tag = reinterpret_cast<const android_event_header_t*>(msg)->tag;
- tag = tags_->tagToName(numeric_tag);
- if (tag) {
- tag_len = strlen(tag);
- }
- } else {
- prio = *msg;
- tag = msg + 1;
- tag_len = strnlen(tag, len - 1);
- }
- return __android_log_is_loggable_len(prio, tag, tag_len, ANDROID_LOG_VERBOSE);
-}
-
-int ChattyLogBuffer::Log(log_id_t log_id, log_time realtime, uid_t uid, pid_t pid, pid_t tid,
- const char* msg, uint16_t len) {
- if (log_id >= LOG_ID_MAX) {
- return -EINVAL;
- }
-
- if (!ShouldLog(log_id, msg, len)) {
- // Log traffic received to total
- stats_->AddTotal(log_id, len);
- return -EACCES;
- }
-
- // 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(log_id, realtime, uid, pid, tid, msg, len);
-
+void ChattyLogBuffer::LogInternal(LogBufferElement&& elem) {
// b/137093665: don't coalesce security messages.
- if (log_id == LOG_ID_SECURITY) {
- auto lock = std::lock_guard{lock_};
- Log(std::move(elem));
- return len;
+ if (elem.getLogId() == LOG_ID_SECURITY) {
+ SimpleLogBuffer::LogInternal(std::move(elem));
+ return;
}
+ int log_id = elem.getLogId();
- auto lock = std::lock_guard{lock_};
// Initialize last_logged_elements_ to a copy of elem if logging the first element for a log_id.
if (!last_logged_elements_[log_id]) {
last_logged_elements_[log_id].emplace(elem);
- Log(std::move(elem));
- return len;
+ SimpleLogBuffer::LogInternal(std::move(elem));
+ return;
}
LogBufferElement& current_last = *last_logged_elements_[log_id];
- enum match_type match = identical(&elem, ¤t_last);
+ enum match_type match = Identical(&elem, ¤t_last);
if (match == DIFFERENT) {
if (duplicate_elements_[log_id]) {
// If we previously had 3+ identical messages, log the chatty message.
if (duplicate_elements_[log_id]->getDropped() > 0) {
- Log(std::move(*duplicate_elements_[log_id]));
+ SimpleLogBuffer::LogInternal(std::move(*duplicate_elements_[log_id]));
}
duplicate_elements_[log_id].reset();
// Log the saved copy of the last identical message seen.
- Log(std::move(current_last));
+ SimpleLogBuffer::LogInternal(std::move(current_last));
}
last_logged_elements_[log_id].emplace(elem);
- Log(std::move(elem));
- return len;
+ SimpleLogBuffer::LogInternal(std::move(elem));
+ return;
}
// 2 identical message: set duplicate_elements_ appropriately.
if (!duplicate_elements_[log_id]) {
duplicate_elements_[log_id].emplace(std::move(current_last));
last_logged_elements_[log_id].emplace(std::move(elem));
- return len;
+ return;
}
// 3+ identical LIBLOG event messages: coalesce them into last_logged_elements_.
@@ -230,47 +154,31 @@
int64_t total = current_last_count + elem_count;
if (total > std::numeric_limits<int32_t>::max()) {
- Log(std::move(current_last));
+ SimpleLogBuffer::LogInternal(std::move(current_last));
last_logged_elements_[log_id].emplace(std::move(elem));
- return len;
+ return;
}
- stats_->AddTotal(current_last.getLogId(), current_last.getMsgLen());
+ stats()->AddTotal(current_last.getLogId(), current_last.getMsgLen());
elem_event->payload.data = total;
last_logged_elements_[log_id].emplace(std::move(elem));
- return len;
+ return;
}
// 3+ identical messages (not LIBLOG) messages: increase the drop count.
uint16_t dropped_count = duplicate_elements_[log_id]->getDropped();
if (dropped_count == std::numeric_limits<uint16_t>::max()) {
- Log(std::move(*duplicate_elements_[log_id]));
+ SimpleLogBuffer::LogInternal(std::move(*duplicate_elements_[log_id]));
dropped_count = 0;
}
// We're dropping the current_last log so add its stats to the total.
- stats_->AddTotal(current_last.getLogId(), current_last.getMsgLen());
+ stats()->AddTotal(current_last.getLogId(), current_last.getMsgLen());
// Use current_last for tracking the dropped count to always use the latest timestamp.
current_last.setDropped(dropped_count + 1);
duplicate_elements_[log_id].emplace(std::move(current_last));
last_logged_elements_[log_id].emplace(std::move(elem));
- return len;
}
-void ChattyLogBuffer::Log(LogBufferElement&& elem) {
- log_id_t log_id = elem.getLogId();
- mLogElements.push_back(std::move(elem));
- stats_->Add(&mLogElements.back());
- maybePrune(log_id);
- reader_list_->NotifyNewLog(1 << log_id);
-}
-
-void ChattyLogBuffer::maybePrune(log_id_t id) {
- unsigned long prune_rows;
- if (stats_->ShouldPrune(id, log_buffer_size(id), &prune_rows)) {
- prune(id, prune_rows);
- }
-}
-
-LogBufferElementCollection::iterator ChattyLogBuffer::erase(LogBufferElementCollection::iterator it,
+LogBufferElementCollection::iterator ChattyLogBuffer::Erase(LogBufferElementCollection::iterator it,
bool coalesce) {
LogBufferElement& element = *it;
log_id_t id = element.getLogId();
@@ -297,9 +205,6 @@
}
}
- bool setLast[LOG_ID_MAX];
- bool doSetLast = false;
- log_id_for_each(i) { doSetLast |= setLast[i] = oldest_[i] && it == *oldest_[i]; }
#ifdef DEBUG_CHECK_FOR_STALE_ENTRIES
LogBufferElementCollection::iterator bad = it;
int key =
@@ -307,25 +212,13 @@
#endif
if (coalesce) {
- stats_->Erase(&element);
+ stats()->Erase(&element);
} else {
- stats_->Subtract(&element);
+ stats()->Subtract(&element);
}
- it = mLogElements.erase(it);
+ it = SimpleLogBuffer::Erase(it);
- if (doSetLast) {
- log_id_for_each(i) {
- if (setLast[i]) {
- if (__predict_false(it == mLogElements.end())) {
- oldest_[i] = std::nullopt;
- } else {
- oldest_[i] = it; // Store the next iterator even if it does not correspond to
- // the same log_id, as a starting point for GetOldest().
- }
- }
- }
- }
#ifdef DEBUG_CHECK_FOR_STALE_ENTRIES
log_id_for_each(i) {
for (auto b : mLastWorst[i]) {
@@ -393,27 +286,6 @@
}
};
-// If the selected reader is blocking our pruning progress, decide on
-// what kind of mitigation is necessary to unblock the situation.
-void ChattyLogBuffer::kickMe(LogReaderThread* 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.
- android::prdebug("Kicking blocked reader, %s, from ChattyLogBuffer::kickMe()\n",
- me->name().c_str());
- me->release_Locked();
- } else if (me->deadline().time_since_epoch().count() != 0) {
- // Allow a blocked WRAP deadline reader to trigger and start reporting the log data.
- me->triggerReader_Locked();
- } else {
- // tell slow reader to skip entries to catch up
- android::prdebug(
- "Skipping %lu entries from slow reader, %s, from ChattyLogBuffer::kickMe()\n",
- pruneRows, me->name().c_str());
- 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
@@ -459,15 +331,15 @@
// 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.
//
-bool ChattyLogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) {
+bool ChattyLogBuffer::Prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) {
LogReaderThread* oldest = nullptr;
bool busy = false;
bool clearAll = pruneRows == ULONG_MAX;
- auto reader_threads_lock = std::lock_guard{reader_list_->reader_threads_lock()};
+ auto reader_threads_lock = std::lock_guard{reader_list()->reader_threads_lock()};
// Region locked?
- for (const auto& reader_thread : reader_list_->reader_threads()) {
+ for (const auto& reader_thread : reader_list()->reader_threads()) {
if (!reader_thread->IsWatching(id)) {
continue;
}
@@ -484,7 +356,7 @@
// Only here if clear all request from non system source, so chatty
// filter logistics is not required.
it = GetOldest(id);
- while (it != mLogElements.end()) {
+ while (it != logs().end()) {
LogBufferElement& element = *it;
if (element.getLogId() != id || element.getUid() != caller_uid) {
@@ -494,11 +366,11 @@
if (oldest && oldest->start() <= element.getSequence()) {
busy = true;
- kickMe(oldest, id, pruneRows);
+ KickReader(oldest, id, pruneRows);
break;
}
- it = erase(it);
+ it = Erase(it);
if (--pruneRows == 0) {
break;
}
@@ -517,16 +389,16 @@
if (worstUidEnabledForLogid(id) && prune_->worstUidEnabled()) {
// Calculate threshold as 12.5% of available storage
- size_t threshold = log_buffer_size(id) / 8;
+ size_t threshold = max_size(id) / 8;
if (id == LOG_ID_EVENTS || id == LOG_ID_SECURITY) {
- stats_->WorstTwoTags(threshold, &worst, &worst_sizes, &second_worst_sizes);
+ stats()->WorstTwoTags(threshold, &worst, &worst_sizes, &second_worst_sizes);
// per-pid filter for AID_SYSTEM sources is too complex
} else {
- stats_->WorstTwoUids(id, threshold, &worst, &worst_sizes, &second_worst_sizes);
+ stats()->WorstTwoUids(id, threshold, &worst, &worst_sizes, &second_worst_sizes);
if (worst == AID_SYSTEM && prune_->worstPidOfSystemEnabled()) {
- stats_->WorstTwoSystemPids(id, worst_sizes, &worstPid, &second_worst_sizes);
+ stats()->WorstTwoSystemPids(id, worst_sizes, &worstPid, &second_worst_sizes);
}
}
}
@@ -547,7 +419,7 @@
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()) {
+ if (found != mLastWorst[id].end() && found->second != logs().end()) {
leading = false;
it = found->second;
}
@@ -556,8 +428,7 @@
// 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()) {
+ if (found != mLastWorstPidOfSystem[id].end() && found->second != logs().end()) {
leading = false;
it = found->second;
}
@@ -568,10 +439,10 @@
}
static const log_time too_old{EXPIRE_HOUR_THRESHOLD * 60 * 60, 0};
LogBufferElementCollection::iterator lastt;
- lastt = mLogElements.end();
+ lastt = logs().end();
--lastt;
LogBufferElementLast last;
- while (it != mLogElements.end()) {
+ while (it != logs().end()) {
LogBufferElement& element = *it;
if (oldest && oldest->start() <= element.getSequence()) {
@@ -590,12 +461,12 @@
// remove any leading drops
if (leading && dropped) {
- it = erase(it);
+ it = Erase(it);
continue;
}
if (dropped && last.coalesce(&element, dropped)) {
- it = erase(it, true);
+ it = Erase(it, true);
continue;
}
@@ -604,7 +475,7 @@
if (hasBlacklist && prune_->naughty(&element)) {
last.clear(&element);
- it = erase(it);
+ it = Erase(it);
if (dropped) {
continue;
}
@@ -667,12 +538,12 @@
// do not create any leading drops
if (leading) {
- it = erase(it);
+ it = Erase(it);
} else {
- stats_->Drop(&element);
+ stats()->Drop(&element);
element.setDropped(1);
if (last.coalesce(&element, 1)) {
- it = erase(it, true);
+ it = Erase(it, true);
} else {
last.add(&element);
if (worstPid && (!gc || mLastWorstPidOfSystem[id].find(worstPid) ==
@@ -703,7 +574,7 @@
bool whitelist = false;
bool hasWhitelist = (id != LOG_ID_SECURITY) && prune_->nice() && !clearAll;
it = GetOldest(id);
- while ((pruneRows > 0) && (it != mLogElements.end())) {
+ while ((pruneRows > 0) && (it != logs().end())) {
LogBufferElement& element = *it;
if (element.getLogId() != id) {
@@ -713,7 +584,7 @@
if (oldest && oldest->start() <= element.getSequence()) {
busy = true;
- if (!whitelist) kickMe(oldest, id, pruneRows);
+ if (!whitelist) KickReader(oldest, id, pruneRows);
break;
}
@@ -724,14 +595,14 @@
continue;
}
- it = erase(it);
+ it = Erase(it);
pruneRows--;
}
// Do not save the whitelist if we are reader range limited
if (whitelist && (pruneRows > 0)) {
it = GetOldest(id);
- while ((it != mLogElements.end()) && (pruneRows > 0)) {
+ while ((it != logs().end()) && (pruneRows > 0)) {
LogBufferElement& element = *it;
if (element.getLogId() != id) {
@@ -741,146 +612,14 @@
if (oldest && oldest->start() <= element.getSequence()) {
busy = true;
- kickMe(oldest, id, pruneRows);
+ KickReader(oldest, id, pruneRows);
break;
}
- it = erase(it);
+ it = Erase(it);
pruneRows--;
}
}
return (pruneRows > 0) && busy;
}
-
-// clear all rows of type "id" from the buffer.
-bool ChattyLogBuffer::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.
- {
- auto lock = std::lock_guard{lock_};
- busy = prune(id, 1, uid);
- }
- // 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) {
- auto reader_threads_lock = std::lock_guard{reader_list_->reader_threads_lock()};
- for (const auto& reader_thread : reader_list_->reader_threads()) {
- if (reader_thread->IsWatching(id)) {
- android::prdebug(
- "Kicking blocked reader, %s, from ChattyLogBuffer::clear()\n",
- reader_thread->name().c_str());
- reader_thread->release_Locked();
- }
- }
- }
- }
- {
- auto lock = std::lock_guard{lock_};
- busy = prune(id, ULONG_MAX, uid);
- }
- if (!busy || !--retry) {
- break;
- }
- sleep(1); // Let reader(s) catch up after notification
- }
- return busy;
-}
-
-// set the total space allocated to "id"
-int ChattyLogBuffer::SetSize(log_id_t id, unsigned long size) {
- // Reasonable limits ...
- if (!__android_logger_valid_buffer_size(size)) {
- return -1;
- }
- auto lock = std::lock_guard{lock_};
- log_buffer_size(id) = size;
- return 0;
-}
-
-// get the total space allocated to "id"
-unsigned long ChattyLogBuffer::GetSize(log_id_t id) {
- auto shared_lock = SharedLock{lock_};
- size_t retval = log_buffer_size(id);
- return retval;
-}
-
-uint64_t ChattyLogBuffer::FlushTo(
- LogWriter* writer, uint64_t start, pid_t* lastTid,
- const std::function<FlushToResult(const LogBufferElement* element)>& filter) {
- LogBufferElementCollection::iterator it;
- uid_t uid = writer->uid();
-
- auto shared_lock = SharedLock{lock_};
-
- 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;
- if (it->getSequence() <= start) {
- it++;
- break;
- }
- }
- }
-
- uint64_t curr = start;
-
- for (; it != mLogElements.end(); ++it) {
- LogBufferElement& element = *it;
-
- if (!writer->privileged() && element.getUid() != uid) {
- continue;
- }
-
- if (!writer->can_read_security_logs() && element.getLogId() == LOG_ID_SECURITY) {
- continue;
- }
-
- // NB: calling out to another object with wrlock() held (safe)
- if (filter) {
- FlushToResult ret = filter(&element);
- if (ret == FlushToResult::kSkip) {
- continue;
- }
- if (ret == FlushToResult::kStop) {
- 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();
- }
-
- shared_lock.unlock();
-
- curr = element.getSequence();
- // range locking in LastLogTimes looks after us
- if (!element.FlushTo(writer, stats_, sameTid)) {
- return FLUSH_ERROR;
- }
-
- shared_lock.lock_shared();
- }
- return curr;
-}
diff --git a/logd/ChattyLogBuffer.h b/logd/ChattyLogBuffer.h
index 08c4bff..6f60272 100644
--- a/logd/ChattyLogBuffer.h
+++ b/logd/ChattyLogBuffer.h
@@ -35,13 +35,12 @@
#include "LogTags.h"
#include "LogWhiteBlackList.h"
#include "LogWriter.h"
+#include "SimpleLogBuffer.h"
#include "rwlock.h"
typedef std::list<LogBufferElement> LogBufferElementCollection;
-class ChattyLogBuffer : public LogBuffer {
- LogBufferElementCollection mLogElements GUARDED_BY(lock_);
-
+class ChattyLogBuffer : public SimpleLogBuffer {
// watermark of any worst/chatty uid processing
typedef std::unordered_map<uid_t, LogBufferElementCollection::iterator> LogBufferIteratorMap;
LogBufferIteratorMap mLastWorst[LOG_ID_MAX] GUARDED_BY(lock_);
@@ -49,48 +48,20 @@
typedef std::unordered_map<pid_t, LogBufferElementCollection::iterator> LogBufferPidIteratorMap;
LogBufferPidIteratorMap mLastWorstPidOfSystem[LOG_ID_MAX] GUARDED_BY(lock_);
- unsigned long mMaxSize[LOG_ID_MAX] GUARDED_BY(lock_);
-
public:
ChattyLogBuffer(LogReaderList* reader_list, LogTags* tags, PruneList* prune,
LogStatistics* stats);
~ChattyLogBuffer();
- void Init() override;
- 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) override;
- uint64_t FlushTo(
- LogWriter* writer, uint64_t start, pid_t* lastTid,
- const std::function<FlushToResult(const LogBufferElement* element)>& filter) override;
-
- bool Clear(log_id_t id, uid_t uid = AID_ROOT) override;
- unsigned long GetSize(log_id_t id) override;
- int SetSize(log_id_t id, unsigned long size) override;
+ protected:
+ bool Prune(log_id_t id, unsigned long pruneRows, uid_t uid) REQUIRES(lock_) override;
+ void LogInternal(LogBufferElement&& elem) REQUIRES(lock_) override;
private:
- void maybePrune(log_id_t id) REQUIRES(lock_);
- void kickMe(LogReaderThread* me, log_id_t id, unsigned long pruneRows) REQUIRES_SHARED(lock_);
-
- bool prune(log_id_t id, unsigned long pruneRows, uid_t uid = AID_ROOT) REQUIRES(lock_);
- LogBufferElementCollection::iterator erase(LogBufferElementCollection::iterator it,
+ LogBufferElementCollection::iterator Erase(LogBufferElementCollection::iterator it,
bool coalesce = false) REQUIRES(lock_);
- bool ShouldLog(log_id_t log_id, const char* msg, uint16_t len);
- void Log(LogBufferElement&& elem) REQUIRES(lock_);
- // Returns an iterator to the oldest element for a given log type, or mLogElements.end() if
- // there are no logs for the given log type. Requires mLogElementsLock to be held.
- LogBufferElementCollection::iterator GetOldest(log_id_t log_id) REQUIRES(lock_);
-
- LogReaderList* reader_list_;
- LogTags* tags_;
PruneList* prune_;
- LogStatistics* stats_;
-
- // Keeps track of the iterator to the oldest log message of a given log type, as an
- // optimization when pruning logs. Use GetOldest() to retrieve.
- std::optional<LogBufferElementCollection::iterator> oldest_[LOG_ID_MAX];
-
- RwLock lock_;
// This always contains a copy of the last message logged, for deduplication.
std::optional<LogBufferElement> last_logged_elements_[LOG_ID_MAX] GUARDED_BY(lock_);
diff --git a/logd/ChattyLogBufferTest.cpp b/logd/ChattyLogBufferTest.cpp
new file mode 100644
index 0000000..2e0c947
--- /dev/null
+++ b/logd/ChattyLogBufferTest.cpp
@@ -0,0 +1,202 @@
+/*
+ * 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.
+ */
+
+#include "LogBufferTest.h"
+
+class ChattyLogBufferTest : public LogBufferTest {};
+
+TEST_P(ChattyLogBufferTest, deduplication_simple) {
+ auto make_message = [&](uint32_t sec, const char* tag, const char* msg,
+ bool regex = false) -> LogMessage {
+ logger_entry entry = {
+ .pid = 1, .tid = 1, .sec = sec, .nsec = 1, .lid = LOG_ID_MAIN, .uid = 0};
+ std::string message;
+ message.push_back(ANDROID_LOG_INFO);
+ message.append(tag);
+ message.push_back('\0');
+ message.append(msg);
+ message.push_back('\0');
+ return {entry, message, regex};
+ };
+
+ // clang-format off
+ std::vector<LogMessage> log_messages = {
+ make_message(0, "test_tag", "duplicate"),
+ make_message(1, "test_tag", "duplicate"),
+ make_message(2, "test_tag", "not_same"),
+ make_message(3, "test_tag", "duplicate"),
+ make_message(4, "test_tag", "duplicate"),
+ make_message(5, "test_tag", "not_same"),
+ make_message(6, "test_tag", "duplicate"),
+ make_message(7, "test_tag", "duplicate"),
+ make_message(8, "test_tag", "duplicate"),
+ make_message(9, "test_tag", "not_same"),
+ make_message(10, "test_tag", "duplicate"),
+ make_message(11, "test_tag", "duplicate"),
+ make_message(12, "test_tag", "duplicate"),
+ make_message(13, "test_tag", "duplicate"),
+ make_message(14, "test_tag", "duplicate"),
+ make_message(15, "test_tag", "duplicate"),
+ make_message(16, "test_tag", "not_same"),
+ make_message(100, "test_tag", "duplicate"),
+ make_message(200, "test_tag", "duplicate"),
+ make_message(300, "test_tag", "duplicate"),
+ };
+ // clang-format on
+ FixupMessages(&log_messages);
+ LogMessages(log_messages);
+
+ std::vector<LogMessage> read_log_messages;
+ std::unique_ptr<LogWriter> test_writer(new TestWriter(&read_log_messages, nullptr));
+ log_buffer_->FlushTo(test_writer.get(), 1, nullptr, nullptr);
+
+ std::vector<LogMessage> expected_log_messages = {
+ make_message(0, "test_tag", "duplicate"),
+ make_message(1, "test_tag", "duplicate"),
+ make_message(2, "test_tag", "not_same"),
+ make_message(3, "test_tag", "duplicate"),
+ make_message(4, "test_tag", "duplicate"),
+ make_message(5, "test_tag", "not_same"),
+ // 3 duplicate logs together print the first, a 1 count chatty message, then the last.
+ make_message(6, "test_tag", "duplicate"),
+ make_message(7, "chatty", "uid=0\\([^\\)]+\\) [^ ]+ expire 1 line", true),
+ make_message(8, "test_tag", "duplicate"),
+ make_message(9, "test_tag", "not_same"),
+ // 6 duplicate logs together print the first, a 4 count chatty message, then the last.
+ make_message(10, "test_tag", "duplicate"),
+ make_message(14, "chatty", "uid=0\\([^\\)]+\\) [^ ]+ expire 4 lines", true),
+ make_message(15, "test_tag", "duplicate"),
+ make_message(16, "test_tag", "not_same"),
+ // duplicate logs > 1 minute apart are not deduplicated.
+ make_message(100, "test_tag", "duplicate"),
+ make_message(200, "test_tag", "duplicate"),
+ make_message(300, "test_tag", "duplicate"),
+ };
+ FixupMessages(&expected_log_messages);
+ CompareLogMessages(expected_log_messages, read_log_messages);
+};
+
+TEST_P(ChattyLogBufferTest, deduplication_overflow) {
+ auto make_message = [&](uint32_t sec, const char* tag, const char* msg,
+ bool regex = false) -> LogMessage {
+ logger_entry entry = {
+ .pid = 1, .tid = 1, .sec = sec, .nsec = 1, .lid = LOG_ID_MAIN, .uid = 0};
+ std::string message;
+ message.push_back(ANDROID_LOG_INFO);
+ message.append(tag);
+ message.push_back('\0');
+ message.append(msg);
+ message.push_back('\0');
+ return {entry, message, regex};
+ };
+
+ uint32_t sec = 0;
+ std::vector<LogMessage> log_messages = {
+ make_message(sec++, "test_tag", "normal"),
+ };
+ size_t expired_per_chatty_message = std::numeric_limits<uint16_t>::max();
+ for (size_t i = 0; i < expired_per_chatty_message + 3; ++i) {
+ log_messages.emplace_back(make_message(sec++, "test_tag", "duplicate"));
+ }
+ log_messages.emplace_back(make_message(sec++, "test_tag", "normal"));
+ FixupMessages(&log_messages);
+ LogMessages(log_messages);
+
+ std::vector<LogMessage> read_log_messages;
+ std::unique_ptr<LogWriter> test_writer(new TestWriter(&read_log_messages, nullptr));
+ log_buffer_->FlushTo(test_writer.get(), 1, nullptr, nullptr);
+
+ std::vector<LogMessage> expected_log_messages = {
+ make_message(0, "test_tag", "normal"),
+ make_message(1, "test_tag", "duplicate"),
+ make_message(expired_per_chatty_message + 1, "chatty",
+ "uid=0\\([^\\)]+\\) [^ ]+ expire 65535 lines", true),
+ make_message(expired_per_chatty_message + 2, "chatty",
+ "uid=0\\([^\\)]+\\) [^ ]+ expire 1 line", true),
+ make_message(expired_per_chatty_message + 3, "test_tag", "duplicate"),
+ make_message(expired_per_chatty_message + 4, "test_tag", "normal"),
+ };
+ FixupMessages(&expected_log_messages);
+ CompareLogMessages(expected_log_messages, read_log_messages);
+}
+
+TEST_P(ChattyLogBufferTest, deduplication_liblog) {
+ auto make_message = [&](uint32_t sec, int32_t tag, int32_t count) -> LogMessage {
+ logger_entry entry = {
+ .pid = 1, .tid = 1, .sec = sec, .nsec = 1, .lid = LOG_ID_EVENTS, .uid = 0};
+ android_log_event_int_t liblog_event = {
+ .header.tag = tag, .payload.type = EVENT_TYPE_INT, .payload.data = count};
+ return {entry, std::string(reinterpret_cast<char*>(&liblog_event), sizeof(liblog_event)),
+ false};
+ };
+
+ // LIBLOG_LOG_TAG
+ std::vector<LogMessage> log_messages = {
+ make_message(0, 1234, 1),
+ make_message(1, LIBLOG_LOG_TAG, 3),
+ make_message(2, 1234, 2),
+ make_message(3, LIBLOG_LOG_TAG, 3),
+ make_message(4, LIBLOG_LOG_TAG, 4),
+ make_message(5, 1234, 223),
+ make_message(6, LIBLOG_LOG_TAG, 2),
+ make_message(7, LIBLOG_LOG_TAG, 3),
+ make_message(8, LIBLOG_LOG_TAG, 4),
+ make_message(9, 1234, 227),
+ make_message(10, LIBLOG_LOG_TAG, 1),
+ make_message(11, LIBLOG_LOG_TAG, 3),
+ make_message(12, LIBLOG_LOG_TAG, 2),
+ make_message(13, LIBLOG_LOG_TAG, 3),
+ make_message(14, LIBLOG_LOG_TAG, 5),
+ make_message(15, 1234, 227),
+ make_message(16, LIBLOG_LOG_TAG, 2),
+ make_message(17, LIBLOG_LOG_TAG, std::numeric_limits<int32_t>::max()),
+ make_message(18, LIBLOG_LOG_TAG, 3),
+ make_message(19, LIBLOG_LOG_TAG, 5),
+ make_message(20, 1234, 227),
+ };
+ FixupMessages(&log_messages);
+ LogMessages(log_messages);
+
+ std::vector<LogMessage> read_log_messages;
+ std::unique_ptr<LogWriter> test_writer(new TestWriter(&read_log_messages, nullptr));
+ log_buffer_->FlushTo(test_writer.get(), 1, nullptr, nullptr);
+
+ std::vector<LogMessage> expected_log_messages = {
+ make_message(0, 1234, 1),
+ make_message(1, LIBLOG_LOG_TAG, 3),
+ make_message(2, 1234, 2),
+ make_message(3, LIBLOG_LOG_TAG, 3),
+ make_message(4, LIBLOG_LOG_TAG, 4),
+ make_message(5, 1234, 223),
+ // More than 2 liblog events (3 here), sum their value into the third message.
+ make_message(6, LIBLOG_LOG_TAG, 2),
+ make_message(8, LIBLOG_LOG_TAG, 7),
+ make_message(9, 1234, 227),
+ // More than 2 liblog events (5 here), sum their value into the third message.
+ make_message(10, LIBLOG_LOG_TAG, 1),
+ make_message(14, LIBLOG_LOG_TAG, 13),
+ make_message(15, 1234, 227),
+ // int32_t max is the max for a chatty message, beyond that we must use new messages.
+ make_message(16, LIBLOG_LOG_TAG, 2),
+ make_message(17, LIBLOG_LOG_TAG, std::numeric_limits<int32_t>::max()),
+ make_message(19, LIBLOG_LOG_TAG, 8),
+ make_message(20, 1234, 227),
+ };
+ FixupMessages(&expected_log_messages);
+ CompareLogMessages(expected_log_messages, read_log_messages);
+};
+
+INSTANTIATE_TEST_CASE_P(ChattyLogBufferTests, ChattyLogBufferTest, testing::Values("chatty"));
\ No newline at end of file
diff --git a/logd/LogBuffer.h b/logd/LogBuffer.h
index 6274051..7f1e128 100644
--- a/logd/LogBuffer.h
+++ b/logd/LogBuffer.h
@@ -53,4 +53,6 @@
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;
};
\ No newline at end of file
diff --git a/logd/LogBufferElement.cpp b/logd/LogBufferElement.cpp
index 3bcf11d..c6dbda8 100644
--- a/logd/LogBufferElement.cpp
+++ b/logd/LogBufferElement.cpp
@@ -30,14 +30,12 @@
#include "LogStatistics.h"
#include "LogUtils.h"
-atomic_int_fast64_t LogBufferElement::sequence(1);
-
LogBufferElement::LogBufferElement(log_id_t log_id, log_time realtime, uid_t uid, pid_t pid,
- pid_t tid, const char* msg, uint16_t len)
+ pid_t tid, uint64_t sequence, const char* msg, uint16_t len)
: mUid(uid),
mPid(pid),
mTid(tid),
- mSequence(sequence.fetch_add(1, memory_order_relaxed)),
+ mSequence(sequence),
mRealTime(realtime),
mMsgLen(len),
mLogId(log_id),
diff --git a/logd/LogBufferElement.h b/logd/LogBufferElement.h
index a777970..35252f9 100644
--- a/logd/LogBufferElement.h
+++ b/logd/LogBufferElement.h
@@ -16,7 +16,6 @@
#pragma once
-#include <stdatomic.h>
#include <stdint.h>
#include <stdlib.h>
#include <sys/types.h>
@@ -51,14 +50,12 @@
const uint8_t mLogId;
bool mDropped;
- static atomic_int_fast64_t sequence;
-
// assumption: mDropped == true
size_t populateDroppedMessage(char*& buffer, LogStatistics* parent, bool lastSame);
public:
- LogBufferElement(log_id_t log_id, log_time realtime, uid_t uid, pid_t pid,
- pid_t tid, const char* msg, uint16_t len);
+ LogBufferElement(log_id_t log_id, log_time realtime, uid_t uid, pid_t pid, pid_t tid,
+ uint64_t sequence, const char* msg, uint16_t len);
LogBufferElement(const LogBufferElement& elem);
LogBufferElement(LogBufferElement&& elem);
~LogBufferElement();
@@ -91,7 +88,6 @@
return mDropped ? nullptr : mMsg;
}
uint64_t getSequence() const { return mSequence; }
- static uint64_t getCurrentSequence() { return sequence.load(memory_order_relaxed); }
log_time getRealTime(void) const {
return mRealTime;
}
diff --git a/logd/LogBufferTest.cpp b/logd/LogBufferTest.cpp
index b52ce8f..334d57b 100644
--- a/logd/LogBufferTest.cpp
+++ b/logd/LogBufferTest.cpp
@@ -1,5 +1,5 @@
/*
- * Copyright (C) 2014 The Android Open Source Project
+ * 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.
@@ -14,7 +14,7 @@
* limitations under the License.
*/
-#include "LogBuffer.h"
+#include "LogBufferTest.h"
#include <unistd.h>
@@ -25,14 +25,8 @@
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
-#include <gtest/gtest.h>
-#include "ChattyLogBuffer.h"
-#include "LogReaderList.h"
#include "LogReaderThread.h"
-#include "LogStatistics.h"
-#include "LogTags.h"
-#include "LogWhiteBlackList.h"
#include "LogWriter.h"
using android::base::Join;
@@ -61,15 +55,8 @@
return nullptr;
}
-struct LogMessage {
- logger_entry entry;
- std::string message;
- bool regex_compare = false; // Only set for expected messages, when true 'message' should be
- // interpretted as a regex.
-};
-
-std::vector<std::string> CompareLoggerEntries(const logger_entry& expected,
- const logger_entry& result, bool ignore_len) {
+static std::vector<std::string> CompareLoggerEntries(const logger_entry& expected,
+ const logger_entry& result, bool ignore_len) {
std::vector<std::string> errors;
if (!ignore_len && expected.len != result.len) {
errors.emplace_back(
@@ -106,7 +93,7 @@
return errors;
}
-std::string MakePrintable(std::string in) {
+static std::string MakePrintable(std::string in) {
if (in.size() > 80) {
in = in.substr(0, 80) + "...";
}
@@ -121,7 +108,7 @@
return result;
}
-std::string CompareMessages(const std::string& expected, const std::string& result) {
+static std::string CompareMessages(const std::string& expected, const std::string& result) {
if (expected == result) {
return {};
}
@@ -145,7 +132,7 @@
result_short.c_str());
}
-std::string CompareRegexMessages(const std::string& expected, const std::string& result) {
+static std::string CompareRegexMessages(const std::string& expected, const std::string& result) {
auto expected_pieces = Split(expected, std::string("\0", 1));
auto result_pieces = Split(result, std::string("\0", 1));
@@ -197,54 +184,14 @@
EXPECT_EQ(0U, num_errors);
}
-class TestWriter : public LogWriter {
- public:
- TestWriter(std::vector<LogMessage>* msgs, bool* released)
- : LogWriter(0, true, true), msgs_(msgs), released_(released) {}
- bool Write(const logger_entry& entry, const char* message) override {
- msgs_->emplace_back(LogMessage{entry, std::string(message, entry.len), false});
- return true;
+void FixupMessages(std::vector<LogMessage>* messages) {
+ for (auto& [entry, message, _] : *messages) {
+ entry.hdr_size = sizeof(logger_entry);
+ entry.len = message.size();
}
+}
- void Release() {
- if (released_) *released_ = true;
- }
-
- std::string name() const override { return "test_writer"; }
-
- private:
- std::vector<LogMessage>* msgs_;
- bool* released_;
-};
-
-class LogBufferTest : public testing::Test {
- protected:
- void SetUp() override {
- log_buffer_.reset(new ChattyLogBuffer(&reader_list_, &tags_, &prune_, &stats_));
- }
-
- void FixupMessages(std::vector<LogMessage>* messages) {
- for (auto& [entry, message, _] : *messages) {
- entry.hdr_size = sizeof(logger_entry);
- entry.len = message.size();
- }
- }
-
- void LogMessages(const std::vector<LogMessage>& messages) {
- for (auto& [entry, message, _] : messages) {
- log_buffer_->Log(static_cast<log_id_t>(entry.lid), log_time(entry.sec, entry.nsec),
- entry.uid, entry.pid, entry.tid, message.c_str(), message.size());
- }
- }
-
- LogReaderList reader_list_;
- LogTags tags_;
- PruneList prune_;
- LogStatistics stats_{false};
- std::unique_ptr<LogBuffer> log_buffer_;
-};
-
-TEST_F(LogBufferTest, smoke) {
+TEST_P(LogBufferTest, smoke) {
std::vector<LogMessage> log_messages = {
{{
.pid = 1,
@@ -266,7 +213,7 @@
CompareLogMessages(log_messages, read_log_messages);
}
-TEST_F(LogBufferTest, smoke_with_reader_thread) {
+TEST_P(LogBufferTest, smoke_with_reader_thread) {
std::vector<LogMessage> log_messages = {
{{.pid = 1, .tid = 2, .sec = 10000, .nsec = 20001, .lid = LOG_ID_MAIN, .uid = 0},
"first"},
@@ -358,7 +305,7 @@
return {entry, message};
}
-TEST_F(LogBufferTest, random_messages) {
+TEST_P(LogBufferTest, random_messages) {
srand(1);
std::vector<LogMessage> log_messages;
for (size_t i = 0; i < 1000; ++i) {
@@ -388,183 +335,4 @@
CompareLogMessages(log_messages, read_log_messages);
}
-TEST_F(LogBufferTest, deduplication_simple) {
- auto make_message = [&](uint32_t sec, const char* tag, const char* msg,
- bool regex = false) -> LogMessage {
- logger_entry entry = {
- .pid = 1, .tid = 1, .sec = sec, .nsec = 1, .lid = LOG_ID_MAIN, .uid = 0};
- std::string message;
- message.push_back(ANDROID_LOG_INFO);
- message.append(tag);
- message.push_back('\0');
- message.append(msg);
- message.push_back('\0');
- return {entry, message, regex};
- };
-
- // clang-format off
- std::vector<LogMessage> log_messages = {
- make_message(0, "test_tag", "duplicate"),
- make_message(1, "test_tag", "duplicate"),
- make_message(2, "test_tag", "not_same"),
- make_message(3, "test_tag", "duplicate"),
- make_message(4, "test_tag", "duplicate"),
- make_message(5, "test_tag", "not_same"),
- make_message(6, "test_tag", "duplicate"),
- make_message(7, "test_tag", "duplicate"),
- make_message(8, "test_tag", "duplicate"),
- make_message(9, "test_tag", "not_same"),
- make_message(10, "test_tag", "duplicate"),
- make_message(11, "test_tag", "duplicate"),
- make_message(12, "test_tag", "duplicate"),
- make_message(13, "test_tag", "duplicate"),
- make_message(14, "test_tag", "duplicate"),
- make_message(15, "test_tag", "duplicate"),
- make_message(16, "test_tag", "not_same"),
- make_message(100, "test_tag", "duplicate"),
- make_message(200, "test_tag", "duplicate"),
- make_message(300, "test_tag", "duplicate"),
- };
- // clang-format on
- FixupMessages(&log_messages);
- LogMessages(log_messages);
-
- std::vector<LogMessage> read_log_messages;
- std::unique_ptr<LogWriter> test_writer(new TestWriter(&read_log_messages, nullptr));
- log_buffer_->FlushTo(test_writer.get(), 1, nullptr, nullptr);
-
- std::vector<LogMessage> expected_log_messages = {
- make_message(0, "test_tag", "duplicate"),
- make_message(1, "test_tag", "duplicate"),
- make_message(2, "test_tag", "not_same"),
- make_message(3, "test_tag", "duplicate"),
- make_message(4, "test_tag", "duplicate"),
- make_message(5, "test_tag", "not_same"),
- // 3 duplicate logs together print the first, a 1 count chatty message, then the last.
- make_message(6, "test_tag", "duplicate"),
- make_message(7, "chatty", "uid=0\\([^\\)]+\\) [^ ]+ expire 1 line", true),
- make_message(8, "test_tag", "duplicate"),
- make_message(9, "test_tag", "not_same"),
- // 6 duplicate logs together print the first, a 4 count chatty message, then the last.
- make_message(10, "test_tag", "duplicate"),
- make_message(14, "chatty", "uid=0\\([^\\)]+\\) [^ ]+ expire 4 lines", true),
- make_message(15, "test_tag", "duplicate"),
- make_message(16, "test_tag", "not_same"),
- // duplicate logs > 1 minute apart are not deduplicated.
- make_message(100, "test_tag", "duplicate"),
- make_message(200, "test_tag", "duplicate"),
- make_message(300, "test_tag", "duplicate"),
- };
- FixupMessages(&expected_log_messages);
- CompareLogMessages(expected_log_messages, read_log_messages);
-};
-
-TEST_F(LogBufferTest, deduplication_overflow) {
- auto make_message = [&](uint32_t sec, const char* tag, const char* msg,
- bool regex = false) -> LogMessage {
- logger_entry entry = {
- .pid = 1, .tid = 1, .sec = sec, .nsec = 1, .lid = LOG_ID_MAIN, .uid = 0};
- std::string message;
- message.push_back(ANDROID_LOG_INFO);
- message.append(tag);
- message.push_back('\0');
- message.append(msg);
- message.push_back('\0');
- return {entry, message, regex};
- };
-
- uint32_t sec = 0;
- std::vector<LogMessage> log_messages = {
- make_message(sec++, "test_tag", "normal"),
- };
- size_t expired_per_chatty_message = std::numeric_limits<uint16_t>::max();
- for (size_t i = 0; i < expired_per_chatty_message + 3; ++i) {
- log_messages.emplace_back(make_message(sec++, "test_tag", "duplicate"));
- }
- log_messages.emplace_back(make_message(sec++, "test_tag", "normal"));
- FixupMessages(&log_messages);
- LogMessages(log_messages);
-
- std::vector<LogMessage> read_log_messages;
- std::unique_ptr<LogWriter> test_writer(new TestWriter(&read_log_messages, nullptr));
- log_buffer_->FlushTo(test_writer.get(), 1, nullptr, nullptr);
-
- std::vector<LogMessage> expected_log_messages = {
- make_message(0, "test_tag", "normal"),
- make_message(1, "test_tag", "duplicate"),
- make_message(expired_per_chatty_message + 1, "chatty",
- "uid=0\\([^\\)]+\\) [^ ]+ expire 65535 lines", true),
- make_message(expired_per_chatty_message + 2, "chatty",
- "uid=0\\([^\\)]+\\) [^ ]+ expire 1 line", true),
- make_message(expired_per_chatty_message + 3, "test_tag", "duplicate"),
- make_message(expired_per_chatty_message + 4, "test_tag", "normal"),
- };
- FixupMessages(&expected_log_messages);
- CompareLogMessages(expected_log_messages, read_log_messages);
-}
-
-TEST_F(LogBufferTest, deduplication_liblog) {
- auto make_message = [&](uint32_t sec, int32_t tag, int32_t count) -> LogMessage {
- logger_entry entry = {
- .pid = 1, .tid = 1, .sec = sec, .nsec = 1, .lid = LOG_ID_EVENTS, .uid = 0};
- android_log_event_int_t liblog_event = {
- .header.tag = tag, .payload.type = EVENT_TYPE_INT, .payload.data = count};
- return {entry, std::string(reinterpret_cast<char*>(&liblog_event), sizeof(liblog_event)),
- false};
- };
-
- // LIBLOG_LOG_TAG
- std::vector<LogMessage> log_messages = {
- make_message(0, 1234, 1),
- make_message(1, LIBLOG_LOG_TAG, 3),
- make_message(2, 1234, 2),
- make_message(3, LIBLOG_LOG_TAG, 3),
- make_message(4, LIBLOG_LOG_TAG, 4),
- make_message(5, 1234, 223),
- make_message(6, LIBLOG_LOG_TAG, 2),
- make_message(7, LIBLOG_LOG_TAG, 3),
- make_message(8, LIBLOG_LOG_TAG, 4),
- make_message(9, 1234, 227),
- make_message(10, LIBLOG_LOG_TAG, 1),
- make_message(11, LIBLOG_LOG_TAG, 3),
- make_message(12, LIBLOG_LOG_TAG, 2),
- make_message(13, LIBLOG_LOG_TAG, 3),
- make_message(14, LIBLOG_LOG_TAG, 5),
- make_message(15, 1234, 227),
- make_message(16, LIBLOG_LOG_TAG, 2),
- make_message(17, LIBLOG_LOG_TAG, std::numeric_limits<int32_t>::max()),
- make_message(18, LIBLOG_LOG_TAG, 3),
- make_message(19, LIBLOG_LOG_TAG, 5),
- make_message(20, 1234, 227),
- };
- FixupMessages(&log_messages);
- LogMessages(log_messages);
-
- std::vector<LogMessage> read_log_messages;
- std::unique_ptr<LogWriter> test_writer(new TestWriter(&read_log_messages, nullptr));
- log_buffer_->FlushTo(test_writer.get(), 1, nullptr, nullptr);
-
- std::vector<LogMessage> expected_log_messages = {
- make_message(0, 1234, 1),
- make_message(1, LIBLOG_LOG_TAG, 3),
- make_message(2, 1234, 2),
- make_message(3, LIBLOG_LOG_TAG, 3),
- make_message(4, LIBLOG_LOG_TAG, 4),
- make_message(5, 1234, 223),
- // More than 2 liblog events (3 here), sum their value into the third message.
- make_message(6, LIBLOG_LOG_TAG, 2),
- make_message(8, LIBLOG_LOG_TAG, 7),
- make_message(9, 1234, 227),
- // More than 2 liblog events (5 here), sum their value into the third message.
- make_message(10, LIBLOG_LOG_TAG, 1),
- make_message(14, LIBLOG_LOG_TAG, 13),
- make_message(15, 1234, 227),
- // int32_t max is the max for a chatty message, beyond that we must use new messages.
- make_message(16, LIBLOG_LOG_TAG, 2),
- make_message(17, LIBLOG_LOG_TAG, std::numeric_limits<int32_t>::max()),
- make_message(19, LIBLOG_LOG_TAG, 8),
- make_message(20, 1234, 227),
- };
- FixupMessages(&expected_log_messages);
- CompareLogMessages(expected_log_messages, read_log_messages);
-};
\ No newline at end of file
+INSTANTIATE_TEST_CASE_P(LogBufferTests, LogBufferTest, testing::Values("chatty", "simple"));
diff --git a/logd/LogBufferTest.h b/logd/LogBufferTest.h
new file mode 100644
index 0000000..1659f12
--- /dev/null
+++ b/logd/LogBufferTest.h
@@ -0,0 +1,89 @@
+/*
+ * 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 <string>
+#include <vector>
+
+#include <gtest/gtest.h>
+
+#include "ChattyLogBuffer.h"
+#include "LogReaderList.h"
+#include "LogStatistics.h"
+#include "LogTags.h"
+#include "LogWhiteBlackList.h"
+#include "SimpleLogBuffer.h"
+
+struct LogMessage {
+ logger_entry entry;
+ std::string message;
+ bool regex_compare = false; // Only set for expected messages, when true 'message' should be
+ // interpretted as a regex.
+};
+
+// Compares the ordered list of expected and result, causing a test failure with appropriate
+// information on failure.
+void CompareLogMessages(const std::vector<LogMessage>& expected,
+ const std::vector<LogMessage>& result);
+// Sets hdr_size and len parameters appropriately.
+void FixupMessages(std::vector<LogMessage>* messages);
+
+class TestWriter : public LogWriter {
+ public:
+ TestWriter(std::vector<LogMessage>* msgs, bool* released)
+ : LogWriter(0, true, true), msgs_(msgs), released_(released) {}
+ bool Write(const logger_entry& entry, const char* message) override {
+ msgs_->emplace_back(LogMessage{entry, std::string(message, entry.len), false});
+ return true;
+ }
+
+ void Release() {
+ if (released_) *released_ = true;
+ }
+
+ std::string name() const override { return "test_writer"; }
+
+ private:
+ std::vector<LogMessage>* msgs_;
+ bool* released_;
+};
+
+class LogBufferTest : public testing::TestWithParam<std::string> {
+ protected:
+ void SetUp() override {
+ if (GetParam() == "chatty") {
+ log_buffer_.reset(new ChattyLogBuffer(&reader_list_, &tags_, &prune_, &stats_));
+ } else if (GetParam() == "simple") {
+ log_buffer_.reset(new SimpleLogBuffer(&reader_list_, &tags_, &stats_));
+ } else {
+ FAIL() << "Unknown buffer type selected for test";
+ }
+ }
+
+ void LogMessages(const std::vector<LogMessage>& messages) {
+ for (auto& [entry, message, _] : messages) {
+ log_buffer_->Log(static_cast<log_id_t>(entry.lid), log_time(entry.sec, entry.nsec),
+ entry.uid, entry.pid, entry.tid, message.c_str(), message.size());
+ }
+ }
+
+ LogReaderList reader_list_;
+ LogTags tags_;
+ PruneList prune_;
+ LogStatistics stats_{false};
+ std::unique_ptr<LogBuffer> log_buffer_;
+};
diff --git a/logd/LogReader.cpp b/logd/LogReader.cpp
index 89562a4..234ddc7 100644
--- a/logd/LogReader.cpp
+++ b/logd/LogReader.cpp
@@ -200,7 +200,7 @@
if (nonBlock) {
return false;
}
- sequence = LogBufferElement::getCurrentSequence();
+ sequence = log_buffer_->sequence();
}
}
diff --git a/logd/LogTags.h b/logd/LogTags.h
index e4d165a..cce700c 100644
--- a/logd/LogTags.h
+++ b/logd/LogTags.h
@@ -14,13 +14,13 @@
* limitations under the License.
*/
-#ifndef _LOGD_LOG_TAGS_H__
-#define _LOGD_LOG_TAGS_H__
+#pragma once
#include <string>
#include <unordered_map>
#include <unordered_set>
+#include <private/android_filesystem_config.h>
#include <utils/RWLock.h>
class LogTags {
@@ -120,5 +120,3 @@
std::string formatGetEventTag(uid_t uid, const char* name,
const char* format);
};
-
-#endif // _LOGD_LOG_TAGS_H__
diff --git a/logd/SimpleLogBuffer.cpp b/logd/SimpleLogBuffer.cpp
new file mode 100644
index 0000000..1c83428
--- /dev/null
+++ b/logd/SimpleLogBuffer.cpp
@@ -0,0 +1,337 @@
+/*
+ * 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.
+ */
+
+#include "SimpleLogBuffer.h"
+
+#include "LogBufferElement.h"
+
+SimpleLogBuffer::SimpleLogBuffer(LogReaderList* reader_list, LogTags* tags, LogStatistics* stats)
+ : reader_list_(reader_list), tags_(tags), stats_(stats) {
+ Init();
+}
+
+SimpleLogBuffer::~SimpleLogBuffer() {}
+
+void SimpleLogBuffer::Init() {
+ log_id_for_each(i) {
+ if (SetSize(i, __android_logger_get_buffer_size(i))) {
+ SetSize(i, LOG_BUFFER_MIN_SIZE);
+ }
+ }
+
+ // Release any sleeping reader threads to dump their current content.
+ auto reader_threads_lock = std::lock_guard{reader_list_->reader_threads_lock()};
+ for (const auto& reader_thread : reader_list_->reader_threads()) {
+ reader_thread->triggerReader_Locked();
+ }
+}
+
+std::list<LogBufferElement>::iterator SimpleLogBuffer::GetOldest(log_id_t log_id) {
+ auto it = logs().begin();
+ if (oldest_[log_id]) {
+ it = *oldest_[log_id];
+ }
+ while (it != logs().end() && it->getLogId() != log_id) {
+ it++;
+ }
+ if (it != logs().end()) {
+ oldest_[log_id] = it;
+ }
+ return it;
+}
+
+bool SimpleLogBuffer::ShouldLog(log_id_t log_id, const char* msg, uint16_t len) {
+ if (log_id == LOG_ID_SECURITY) {
+ return true;
+ }
+
+ int prio = ANDROID_LOG_INFO;
+ const char* tag = nullptr;
+ size_t tag_len = 0;
+ if (log_id == LOG_ID_EVENTS || log_id == LOG_ID_STATS) {
+ if (len < sizeof(android_event_header_t)) {
+ return false;
+ }
+ int32_t numeric_tag = reinterpret_cast<const android_event_header_t*>(msg)->tag;
+ tag = tags_->tagToName(numeric_tag);
+ if (tag) {
+ tag_len = strlen(tag);
+ }
+ } else {
+ prio = *msg;
+ tag = msg + 1;
+ tag_len = strnlen(tag, len - 1);
+ }
+ return __android_log_is_loggable_len(prio, tag, tag_len, ANDROID_LOG_VERBOSE);
+}
+
+int SimpleLogBuffer::Log(log_id_t log_id, log_time realtime, uid_t uid, pid_t pid, pid_t tid,
+ const char* msg, uint16_t len) {
+ if (log_id >= LOG_ID_MAX) {
+ return -EINVAL;
+ }
+
+ if (!ShouldLog(log_id, msg, len)) {
+ // Log traffic received to total
+ stats_->AddTotal(log_id, len);
+ return -EACCES;
+ }
+
+ // 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;
+
+ auto lock = std::lock_guard{lock_};
+ auto sequence = sequence_.fetch_add(1, std::memory_order_relaxed);
+ LogInternal(LogBufferElement(log_id, realtime, uid, pid, tid, sequence, msg, len));
+ return len;
+}
+
+void SimpleLogBuffer::LogInternal(LogBufferElement&& elem) {
+ log_id_t log_id = elem.getLogId();
+
+ logs_.emplace_back(std::move(elem));
+ stats_->Add(&logs_.back());
+ MaybePrune(log_id);
+ reader_list_->NotifyNewLog(1 << log_id);
+}
+
+uint64_t SimpleLogBuffer::FlushTo(
+ LogWriter* writer, uint64_t start, pid_t* last_tid,
+ const std::function<FlushToResult(const LogBufferElement* element)>& filter) {
+ auto shared_lock = SharedLock{lock_};
+
+ std::list<LogBufferElement>::iterator it;
+ if (start <= 1) {
+ // client wants to start from the beginning
+ it = logs_.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 = logs_.end(); it != logs_.begin();
+ /* do nothing */) {
+ --it;
+ if (it->getSequence() <= start) {
+ it++;
+ break;
+ }
+ }
+ }
+
+ uint64_t curr = start;
+
+ for (; it != logs_.end(); ++it) {
+ LogBufferElement& element = *it;
+
+ if (!writer->privileged() && element.getUid() != writer->uid()) {
+ continue;
+ }
+
+ if (!writer->can_read_security_logs() && element.getLogId() == LOG_ID_SECURITY) {
+ continue;
+ }
+
+ if (filter) {
+ FlushToResult ret = filter(&element);
+ if (ret == FlushToResult::kSkip) {
+ continue;
+ }
+ if (ret == FlushToResult::kStop) {
+ break;
+ }
+ }
+
+ bool same_tid = false;
+ if (last_tid) {
+ same_tid = last_tid[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.
+ last_tid[element.getLogId()] =
+ (element.getDropped() && !same_tid) ? 0 : element.getTid();
+ }
+
+ shared_lock.unlock();
+
+ // We never prune logs equal to or newer than any LogReaderThreads' `start` value, so the
+ // `element` pointer is safe here without the lock
+ curr = element.getSequence();
+ if (!element.FlushTo(writer, stats_, same_tid)) {
+ return FLUSH_ERROR;
+ }
+
+ shared_lock.lock_shared();
+ }
+
+ return curr;
+}
+
+// clear all rows of type "id" from the buffer.
+bool SimpleLogBuffer::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.
+ {
+ auto lock = std::lock_guard{lock_};
+ busy = Prune(id, 1, uid);
+ }
+ // 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) {
+ auto reader_threads_lock = std::lock_guard{reader_list_->reader_threads_lock()};
+ for (const auto& reader_thread : reader_list_->reader_threads()) {
+ if (reader_thread->IsWatching(id)) {
+ android::prdebug("Kicking blocked reader, %s, from LogBuffer::clear()\n",
+ reader_thread->name().c_str());
+ reader_thread->release_Locked();
+ }
+ }
+ }
+ }
+ {
+ auto lock = std::lock_guard{lock_};
+ busy = Prune(id, ULONG_MAX, uid);
+ }
+
+ if (!busy || !--retry) {
+ break;
+ }
+ sleep(1); // Let reader(s) catch up after notification
+ }
+ return busy;
+}
+
+// get the total space allocated to "id"
+unsigned long SimpleLogBuffer::GetSize(log_id_t id) {
+ auto lock = SharedLock{lock_};
+ size_t retval = max_size_[id];
+ return retval;
+}
+
+// set the total space allocated to "id"
+int SimpleLogBuffer::SetSize(log_id_t id, unsigned long size) {
+ // Reasonable limits ...
+ if (!__android_logger_valid_buffer_size(size)) {
+ return -1;
+ }
+
+ auto lock = std::lock_guard{lock_};
+ max_size_[id] = size;
+ return 0;
+}
+
+void SimpleLogBuffer::MaybePrune(log_id_t id) {
+ unsigned long prune_rows;
+ if (stats_->ShouldPrune(id, max_size_[id], &prune_rows)) {
+ Prune(id, prune_rows, 0);
+ }
+}
+
+bool SimpleLogBuffer::Prune(log_id_t id, unsigned long prune_rows, uid_t caller_uid) {
+ auto reader_threads_lock = std::lock_guard{reader_list_->reader_threads_lock()};
+
+ // Don't prune logs that are newer than the point at which any reader threads are reading from.
+ LogReaderThread* oldest = nullptr;
+ for (const auto& reader_thread : reader_list_->reader_threads()) {
+ if (!reader_thread->IsWatching(id)) {
+ continue;
+ }
+ if (!oldest || oldest->start() > reader_thread->start() ||
+ (oldest->start() == reader_thread->start() &&
+ reader_thread->deadline().time_since_epoch().count() != 0)) {
+ oldest = reader_thread.get();
+ }
+ }
+
+ auto it = GetOldest(id);
+
+ while (it != logs_.end()) {
+ LogBufferElement& element = *it;
+
+ if (element.getLogId() != id) {
+ ++it;
+ continue;
+ }
+
+ if (caller_uid != 0 && element.getUid() != caller_uid) {
+ ++it;
+ continue;
+ }
+
+ if (oldest && oldest->start() <= element.getSequence()) {
+ KickReader(oldest, id, prune_rows);
+ return true;
+ }
+
+ stats_->Subtract(&element);
+ it = Erase(it);
+ if (--prune_rows == 0) {
+ return false;
+ }
+ }
+ return false;
+}
+
+std::list<LogBufferElement>::iterator SimpleLogBuffer::Erase(
+ std::list<LogBufferElement>::iterator it) {
+ bool oldest_is_it[LOG_ID_MAX];
+ log_id_for_each(i) { oldest_is_it[i] = oldest_[i] && it == *oldest_[i]; }
+
+ it = logs_.erase(it);
+
+ log_id_for_each(i) {
+ if (oldest_is_it[i]) {
+ if (__predict_false(it == logs().end())) {
+ oldest_[i] = std::nullopt;
+ } else {
+ oldest_[i] = it; // Store the next iterator even if it does not correspond to
+ // the same log_id, as a starting point for GetOldest().
+ }
+ }
+ }
+
+ return it;
+}
+
+// If the selected reader is blocking our pruning progress, decide on
+// what kind of mitigation is necessary to unblock the situation.
+void SimpleLogBuffer::KickReader(LogReaderThread* reader, log_id_t id, unsigned long prune_rows) {
+ if (stats_->Sizes(id) > (2 * max_size_[id])) { // +100%
+ // A misbehaving or slow reader has its connection
+ // dropped if we hit too much memory pressure.
+ android::prdebug("Kicking blocked reader, %s, from LogBuffer::kickMe()\n",
+ reader->name().c_str());
+ reader->release_Locked();
+ } else if (reader->deadline().time_since_epoch().count() != 0) {
+ // Allow a blocked WRAP deadline reader to trigger and start reporting the log data.
+ reader->triggerReader_Locked();
+ } else {
+ // tell slow reader to skip entries to catch up
+ android::prdebug("Skipping %lu entries from slow reader, %s, from LogBuffer::kickMe()\n",
+ prune_rows, reader->name().c_str());
+ reader->triggerSkip_Locked(id, prune_rows);
+ }
+}
diff --git a/logd/SimpleLogBuffer.h b/logd/SimpleLogBuffer.h
new file mode 100644
index 0000000..9a2d01a
--- /dev/null
+++ b/logd/SimpleLogBuffer.h
@@ -0,0 +1,82 @@
+/*
+ * 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 <atomic>
+#include <list>
+#include <mutex>
+
+#include "LogBuffer.h"
+#include "LogBufferElement.h"
+#include "LogReaderList.h"
+#include "LogStatistics.h"
+#include "LogTags.h"
+#include "rwlock.h"
+
+class SimpleLogBuffer : public LogBuffer {
+ public:
+ SimpleLogBuffer(LogReaderList* reader_list, LogTags* tags, LogStatistics* stats);
+ ~SimpleLogBuffer();
+ void Init() override;
+
+ 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) override;
+ uint64_t FlushTo(
+ LogWriter* writer, uint64_t start, pid_t* lastTid,
+ const std::function<FlushToResult(const LogBufferElement* element)>& filter) override;
+
+ bool Clear(log_id_t id, uid_t uid) override;
+ unsigned long GetSize(log_id_t id) override;
+ int SetSize(log_id_t id, unsigned long size) override;
+
+ uint64_t sequence() const override { return sequence_.load(std::memory_order_relaxed); }
+
+ protected:
+ virtual bool Prune(log_id_t id, unsigned long prune_rows, uid_t uid) REQUIRES(lock_);
+ virtual void LogInternal(LogBufferElement&& elem) REQUIRES(lock_);
+
+ // Returns an iterator to the oldest element for a given log type, or logs_.end() if
+ // there are no logs for the given log type. Requires logs_lock_ to be held.
+ std::list<LogBufferElement>::iterator GetOldest(log_id_t log_id) REQUIRES(lock_);
+ std::list<LogBufferElement>::iterator Erase(std::list<LogBufferElement>::iterator it)
+ REQUIRES(lock_);
+ void KickReader(LogReaderThread* reader, log_id_t id, unsigned long prune_rows)
+ REQUIRES_SHARED(lock_);
+
+ LogStatistics* stats() { return stats_; }
+ LogReaderList* reader_list() { return reader_list_; }
+ unsigned long max_size(log_id_t id) REQUIRES_SHARED(lock_) { return max_size_[id]; }
+ std::list<LogBufferElement>& logs() { return logs_; }
+
+ RwLock lock_;
+
+ private:
+ bool ShouldLog(log_id_t log_id, const char* msg, uint16_t len);
+ void MaybePrune(log_id_t id) REQUIRES(lock_);
+
+ LogReaderList* reader_list_;
+ LogTags* tags_;
+ LogStatistics* stats_;
+
+ std::atomic<uint64_t> sequence_ = 1;
+
+ unsigned long max_size_[LOG_ID_MAX] GUARDED_BY(lock_);
+ std::list<LogBufferElement> logs_ GUARDED_BY(lock_);
+ // Keeps track of the iterator to the oldest log message of a given log type, as an
+ // optimization when pruning logs. Use GetOldest() to retrieve.
+ std::optional<std::list<LogBufferElement>::iterator> oldest_[LOG_ID_MAX] GUARDED_BY(lock_);
+};
diff --git a/logd/main.cpp b/logd/main.cpp
index 1deca72..c2b5a1d 100644
--- a/logd/main.cpp
+++ b/logd/main.cpp
@@ -56,6 +56,7 @@
#include "LogStatistics.h"
#include "LogTags.h"
#include "LogUtils.h"
+#include "SimpleLogBuffer.h"
#define KMSG_PRIORITY(PRI) \
'<', '0' + LOG_MAKEPRI(LOG_DAEMON, LOG_PRI(PRI)) / 10, \
@@ -287,9 +288,13 @@
// entries.
LogReaderList reader_list;
- // LogBuffer is the object which is responsible for holding all
- // log entries.
- LogBuffer* logBuf = new ChattyLogBuffer(&reader_list, &log_tags, &prune_list, &log_statistics);
+ // LogBuffer is the object which is responsible for holding all log entries.
+ LogBuffer* logBuf;
+ if (true) {
+ logBuf = new ChattyLogBuffer(&reader_list, &log_tags, &prune_list, &log_statistics);
+ } else {
+ logBuf = new SimpleLogBuffer(&reader_list, &log_tags, &log_statistics);
+ }
// LogReader listens on /dev/socket/logdr. When a client
// connects, log entries in the LogBuffer are written to the client.