logd: make LogBuffer an interface

We may use different implementations of LogBuffer in the future, so we
make it interface and create a concrete ChattyLogBuffer class that
implements it.

Test: logging unit tests
Change-Id: I5731d6404640664c9acc26b7c677dff3110c6a11
diff --git a/logd/Android.bp b/logd/Android.bp
index 4f1b2b2..80e3cb2 100644
--- a/logd/Android.bp
+++ b/logd/Android.bp
@@ -33,12 +33,12 @@
 
     srcs: [
         "LogCommand.cpp",
+        "ChattyLogBuffer.cpp",
         "CommandListener.cpp",
         "LogListener.cpp",
         "LogReader.cpp",
         "LogReaderList.cpp",
         "LogReaderThread.cpp",
-        "LogBuffer.cpp",
         "LogBufferElement.cpp",
         "LogStatistics.cpp",
         "LogWhiteBlackList.cpp",
diff --git a/logd/LogBuffer.cpp b/logd/ChattyLogBuffer.cpp
similarity index 86%
rename from logd/LogBuffer.cpp
rename to logd/ChattyLogBuffer.cpp
index bb54a5a..fa5bcee 100644
--- a/logd/LogBuffer.cpp
+++ b/logd/ChattyLogBuffer.cpp
@@ -13,9 +13,11 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-// for manual checking of stale entries during LogBuffer::erase()
+// for manual checking of stale entries during ChattyLogBuffer::erase()
 //#define DEBUG_CHECK_FOR_STALE_ENTRIES
 
+#include "ChattyLogBuffer.h"
+
 #include <ctype.h>
 #include <endian.h>
 #include <errno.h>
@@ -32,7 +34,6 @@
 #include <cutils/properties.h>
 #include <private/android_logger.h>
 
-#include "LogBuffer.h"
 #include "LogKlog.h"
 #include "LogReader.h"
 #include "LogUtils.h"
@@ -44,10 +45,10 @@
 // Default
 #define log_buffer_size(id) mMaxSize[id]
 
-void LogBuffer::init() {
+void ChattyLogBuffer::Init() {
     log_id_for_each(i) {
-        if (setSize(i, __android_logger_get_buffer_size(i))) {
-            setSize(i, LOG_BUFFER_MIN_SIZE);
+        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.
@@ -57,8 +58,8 @@
     }
 }
 
-LogBuffer::LogBuffer(LogReaderList* reader_list, LogTags* tags, PruneList* prune,
-                     LogStatistics* stats)
+ChattyLogBuffer::ChattyLogBuffer(LogReaderList* reader_list, LogTags* tags, PruneList* prune,
+                                 LogStatistics* stats)
     : reader_list_(reader_list), tags_(tags), prune_(prune), stats_(stats) {
     pthread_rwlock_init(&mLogElementsLock, nullptr);
 
@@ -67,17 +68,17 @@
         droppedElements[i] = nullptr;
     }
 
-    init();
+    Init();
 }
 
-LogBuffer::~LogBuffer() {
+ChattyLogBuffer::~ChattyLogBuffer() {
     log_id_for_each(i) {
         delete lastLoggedElements[i];
         delete droppedElements[i];
     }
 }
 
-LogBufferElementCollection::iterator LogBuffer::GetOldest(log_id_t log_id) {
+LogBufferElementCollection::iterator ChattyLogBuffer::GetOldest(log_id_t log_id) {
     auto it = mLogElements.begin();
     if (oldest_[log_id]) {
         it = *oldest_[log_id];
@@ -93,8 +94,7 @@
 
 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();
@@ -108,8 +108,7 @@
     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))
+    if (elem->getRealTime().nsec() > (last->getRealTime().nsec() + 60 * NS_PER_SEC))
         return DIFFERENT;
 
     // Identical message
@@ -118,21 +117,17 @@
     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)) {
+        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() &&
-        (lenl > static_cast<ssize_t>(sizeof(android_log_event_string_t))) &&
-        (lenr > static_cast<ssize_t>(sizeof(android_log_event_string_t)))) {
-        if (fastcmp<memcmp>(msgl, msgr, sizeof(android_log_event_string_t) -
-                                            sizeof(int32_t))) {
+    if (last->isBinary() && lenl > static_cast<ssize_t>(sizeof(android_log_event_string_t)) &&
+        lenr > static_cast<ssize_t>(sizeof(android_log_event_string_t))) {
+        if (fastcmp<memcmp>(msgl, msgr, sizeof(android_log_event_string_t) - sizeof(int32_t))) {
             return DIFFERENT;
         }
         msgl += sizeof(android_log_event_string_t);
@@ -148,15 +143,14 @@
     if (!avcr) return DIFFERENT;
     lenr -= avcr - msgr;
     if (lenl != lenr) return DIFFERENT;
-    if (fastcmp<memcmp>(avcl + strlen(avc), avcr + strlen(avc),
-                        lenl - strlen(avc))) {
+    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, uint16_t len) {
+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;
     }
@@ -278,8 +272,7 @@
             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*>(
+                    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:
@@ -290,7 +283,7 @@
                     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()));
+                            const_cast<char*>(elem->getMsg()));
                     swab = event->payload.data;
 
                     lastLoggedElements[LOG_ID_EVENTS] = elem;
@@ -345,24 +338,24 @@
     return len;
 }
 
-// assumes LogBuffer::wrlock() held, owns elem, look after garbage collection
-void LogBuffer::log(LogBufferElement* elem) {
+// assumes ChattyLogBuffer::wrlock() held, owns elem, look after garbage collection
+void ChattyLogBuffer::log(LogBufferElement* elem) {
     mLogElements.push_back(elem);
     stats_->Add(elem);
     maybePrune(elem->getLogId());
     reader_list_->NotifyNewLog(1 << elem->getLogId());
 }
 
-// LogBuffer::wrlock() must be held when this function is called.
-void LogBuffer::maybePrune(log_id_t id) {
+// ChattyLogBuffer::wrlock() must be held when this function is called.
+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 LogBuffer::erase(
-    LogBufferElementCollection::iterator it, bool coalesce) {
+LogBufferElementCollection::iterator ChattyLogBuffer::erase(LogBufferElementCollection::iterator it,
+                                                            bool coalesce) {
     LogBufferElement* element = *it;
     log_id_t id = element->getLogId();
 
@@ -370,9 +363,8 @@
     // 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();
+        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);
@@ -383,10 +375,8 @@
         // 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)) {
+        LogBufferPidIteratorMap::iterator found = mLastWorstPidOfSystem[id].find(element->getPid());
+        if (found != mLastWorstPidOfSystem[id].end() && it == found->second) {
             mLastWorstPidOfSystem[id].erase(found);
         }
     }
@@ -396,9 +386,8 @@
     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 = ((id == LOG_ID_EVENTS) || (id == LOG_ID_SECURITY))
-                  ? element->getTag()
-                  : element->getUid();
+    int key =
+            (id == LOG_ID_EVENTS || id == LOG_ID_SECURITY) ? element->getTag() : element->getUid();
 #endif
     it = mLogElements.erase(it);
     if (doSetLast) {
@@ -417,14 +406,12 @@
     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);
+                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);
+                android::prdebug("stale mLastWorstPidOfSystem[%d] pid=%d\n", i, b.first);
             }
         }
     }
@@ -452,26 +439,20 @@
         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) {
-    }
+  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;
-    }
+    uint64_t getKey() { return value; }
 };
 
 class LogBufferElementLast {
     typedef std::unordered_map<uint64_t, LogBufferElement*> LogBufferElementMap;
     LogBufferElementMap map;
 
-   public:
+  public:
     bool coalesce(LogBufferElement* element, uint16_t dropped) {
-        LogBufferElementKey key(element->getUid(), element->getPid(),
-                                element->getTid());
+        LogBufferElementKey key(element->getUid(), element->getPid(), element->getTid());
         LogBufferElementMap::iterator it = map.find(key.getKey());
         if (it != map.end()) {
             LogBufferElement* found = it->second;
@@ -487,14 +468,11 @@
     }
 
     void add(LogBufferElement* element) {
-        LogBufferElementKey key(element->getUid(), element->getPid(),
-                                element->getTid());
+        LogBufferElementKey key(element->getUid(), element->getPid(), element->getTid());
         map[key.getKey()] = element;
     }
 
-    inline void clear() {
-        map.clear();
-    }
+    void clear() { map.clear(); }
 
     void clear(LogBufferElement* element) {
         uint64_t current = element->getRealTime().nsec() - (EXPIRE_RATELIMIT * NS_PER_SEC);
@@ -512,11 +490,11 @@
 
 // If the selected reader is blocking our pruning progress, decide on
 // what kind of mitigation is necessary to unblock the situation.
-void LogBuffer::kickMe(LogReaderThread* me, log_id_t id, unsigned long pruneRows) {
+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, pid %d, from LogBuffer::kickMe()\n",
+        android::prdebug("Kicking blocked reader, pid %d, from ChattyLogBuffer::kickMe()\n",
                          me->client()->getPid());
         me->release_Locked();
     } else if (me->deadline().time_since_epoch().count() != 0) {
@@ -525,7 +503,7 @@
     } else {
         // tell slow reader to skip entries to catch up
         android::prdebug(
-                "Skipping %lu entries from slow reader, pid %d, from LogBuffer::kickMe()\n",
+                "Skipping %lu entries from slow reader, pid %d, from ChattyLogBuffer::kickMe()\n",
                 pruneRows, me->client()->getPid());
         me->triggerSkip_Locked(id, pruneRows);
     }
@@ -576,9 +554,9 @@
 // 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.
+// ChattyLogBuffer::wrlock() must be held when this function is called.
 //
-bool LogBuffer::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;
@@ -606,8 +584,7 @@
         while (it != mLogElements.end()) {
             LogBufferElement* element = *it;
 
-            if ((element->getLogId() != id) ||
-                (element->getUid() != caller_uid)) {
+            if (element->getLogId() != id || element->getUid() != caller_uid) {
                 ++it;
                 continue;
             }
@@ -666,10 +643,8 @@
         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())) {
+                LogBufferIteratorMap::iterator found = mLastWorst[id].find(worst);
+                if (found != mLastWorst[id].end() && found->second != mLogElements.end()) {
                     leading = false;
                     it = found->second;
                 }
@@ -677,10 +652,9 @@
             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())) {
+                LogBufferPidIteratorMap::iterator found = mLastWorstPidOfSystem[id].find(worstPid);
+                if (found != mLastWorstPidOfSystem[id].end() &&
+                    found->second != mLogElements.end()) {
                     leading = false;
                     it = found->second;
                 }
@@ -689,7 +663,7 @@
         if (leading) {
             it = GetOldest(id);
         }
-        static const timespec too_old = { EXPIRE_HOUR_THRESHOLD * 60 * 60, 0 };
+        static const timespec too_old = {EXPIRE_HOUR_THRESHOLD * 60 * 60, 0};
         LogBufferElementCollection::iterator lastt;
         lastt = mLogElements.end();
         --lastt;
@@ -722,9 +696,8 @@
                 continue;
             }
 
-            int key = ((id == LOG_ID_EVENTS) || (id == LOG_ID_SECURITY))
-                          ? element->getTag()
-                          : element->getUid();
+            int key = (id == LOG_ID_EVENTS || id == LOG_ID_SECURITY) ? element->getTag()
+                                                                     : element->getUid();
 
             if (hasBlacklist && prune_->naughty(element)) {
                 last.clear(element);
@@ -755,10 +728,9 @@
 
             if (dropped) {
                 last.add(element);
-                if (worstPid &&
-                    ((!gc && (element->getPid() == worstPid)) ||
-                     (mLastWorstPidOfSystem[id].find(element->getPid()) ==
-                      mLastWorstPidOfSystem[id].end()))) {
+                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.
@@ -772,8 +744,7 @@
                 continue;
             }
 
-            if ((key != worst) ||
-                (worstPid && (element->getPid() != worstPid))) {
+            if (key != worst || (worstPid && element->getPid() != worstPid)) {
                 leading = false;
                 last.clear(element);
                 ++it;
@@ -801,16 +772,14 @@
                     it = erase(it, true);
                 } else {
                     last.add(element);
-                    if (worstPid &&
-                        (!gc || (mLastWorstPidOfSystem[id].find(worstPid) ==
-                                 mLastWorstPidOfSystem[id].end()))) {
+                    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())) {
+                    if ((!gc && !worstPid) || mLastWorst[id].find(worst) == mLastWorst[id].end()) {
                         mLastWorst[id][worst] = it;
                     }
                     ++it;
@@ -882,7 +851,7 @@
 }
 
 // clear all rows of type "id" from the buffer.
-bool LogBuffer::clear(log_id_t id, uid_t uid) {
+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;;) {
@@ -903,7 +872,7 @@
                 for (const auto& reader_thread : reader_list_->reader_threads()) {
                     if (reader_thread->IsWatching(id)) {
                         android::prdebug(
-                                "Kicking blocked reader, pid %d, from LogBuffer::clear()\n",
+                                "Kicking blocked reader, pid %d, from ChattyLogBuffer::clear()\n",
                                 reader_thread->client()->getPid());
                         reader_thread->release_Locked();
                     }
@@ -922,7 +891,7 @@
 }
 
 // set the total space allocated to "id"
-int LogBuffer::setSize(log_id_t id, unsigned long size) {
+int ChattyLogBuffer::SetSize(log_id_t id, unsigned long size) {
     // Reasonable limits ...
     if (!__android_logger_valid_buffer_size(size)) {
         return -1;
@@ -934,14 +903,14 @@
 }
 
 // get the total space allocated to "id"
-unsigned long LogBuffer::getSize(log_id_t id) {
+unsigned long ChattyLogBuffer::GetSize(log_id_t id) {
     rdlock();
     size_t retval = log_buffer_size(id);
     unlock();
     return retval;
 }
 
-uint64_t LogBuffer::flushTo(
+uint64_t ChattyLogBuffer::FlushTo(
         SocketClient* reader, uint64_t start, pid_t* lastTid, bool privileged, bool security,
         const std::function<FlushToResult(const LogBufferElement* element)>& filter) {
     LogBufferElementCollection::iterator it;
@@ -999,7 +968,7 @@
             // 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();
+                    (element->getDropped() && !sameTid) ? 0 : element->getTid();
         }
 
         unlock();
diff --git a/logd/ChattyLogBuffer.h b/logd/ChattyLogBuffer.h
new file mode 100644
index 0000000..d9cd24f
--- /dev/null
+++ b/logd/ChattyLogBuffer.h
@@ -0,0 +1,97 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <sys/types.h>
+
+#include <list>
+#include <optional>
+#include <string>
+
+#include <android/log.h>
+#include <private/android_filesystem_config.h>
+#include <sysutils/SocketClient.h>
+
+#include "LogBuffer.h"
+#include "LogBufferElement.h"
+#include "LogStatistics.h"
+#include "LogTags.h"
+#include "LogWhiteBlackList.h"
+
+typedef std::list<LogBufferElement*> LogBufferElementCollection;
+
+class LogReaderList;
+class LogReaderThread;
+
+class ChattyLogBuffer : public LogBuffer {
+    LogBufferElementCollection mLogElements;
+    pthread_rwlock_t mLogElementsLock;
+
+    // watermark of any worst/chatty uid processing
+    typedef std::unordered_map<uid_t, LogBufferElementCollection::iterator> LogBufferIteratorMap;
+    LogBufferIteratorMap mLastWorst[LOG_ID_MAX];
+    // watermark of any worst/chatty pid of system processing
+    typedef std::unordered_map<pid_t, LogBufferElementCollection::iterator> LogBufferPidIteratorMap;
+    LogBufferPidIteratorMap mLastWorstPidOfSystem[LOG_ID_MAX];
+
+    unsigned long mMaxSize[LOG_ID_MAX];
+
+    LogBufferElement* lastLoggedElements[LOG_ID_MAX];
+    LogBufferElement* droppedElements[LOG_ID_MAX];
+    void log(LogBufferElement* elem);
+
+  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(
+            SocketClient* writer, uint64_t start, pid_t* lastTid, bool privileged, bool security,
+            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;
+
+  private:
+    void wrlock() { pthread_rwlock_wrlock(&mLogElementsLock); }
+    void rdlock() { pthread_rwlock_rdlock(&mLogElementsLock); }
+    void unlock() { pthread_rwlock_unlock(&mLogElementsLock); }
+
+    void maybePrune(log_id_t id);
+    void kickMe(LogReaderThread* me, log_id_t id, unsigned long pruneRows);
+
+    bool prune(log_id_t id, unsigned long pruneRows, uid_t uid = AID_ROOT);
+    LogBufferElementCollection::iterator erase(LogBufferElementCollection::iterator it,
+                                               bool coalesce = false);
+
+    // 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);
+
+    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];
+};
diff --git a/logd/CommandListener.cpp b/logd/CommandListener.cpp
index 87402ac..0ff19f8 100644
--- a/logd/CommandListener.cpp
+++ b/logd/CommandListener.cpp
@@ -81,7 +81,7 @@
         return 0;
     }
 
-    cli->sendMsg(buf()->clear((log_id_t)id, uid) ? "busy" : "success");
+    cli->sendMsg(buf()->Clear((log_id_t)id, uid) ? "busy" : "success");
     return 0;
 }
 
@@ -99,7 +99,7 @@
         return 0;
     }
 
-    unsigned long size = buf()->getSize((log_id_t)id);
+    unsigned long size = buf()->GetSize((log_id_t)id);
     char buf[512];
     snprintf(buf, sizeof(buf), "%lu", size);
     cli->sendMsg(buf);
@@ -126,7 +126,7 @@
     }
 
     unsigned long size = atol(argv[2]);
-    if (buf()->setSize((log_id_t)id, size)) {
+    if (buf()->SetSize((log_id_t)id, size)) {
         cli->sendMsg("Range Error");
         return 0;
     }
@@ -299,7 +299,7 @@
     setname();
 
     android::prdebug("logd reinit");
-    buf()->init();
+    buf()->Init();
     prune()->init(nullptr);
 
     // This only works on userdebug and eng devices to re-read the
diff --git a/logd/LogAudit.cpp b/logd/LogAudit.cpp
index 520acaf..0ce9796 100644
--- a/logd/LogAudit.cpp
+++ b/logd/LogAudit.cpp
@@ -274,9 +274,8 @@
         memcpy(event->data + str_len - denial_metadata.length(),
                denial_metadata.c_str(), denial_metadata.length());
 
-        rc = logbuf->log(
-            LOG_ID_EVENTS, now, uid, pid, tid, reinterpret_cast<char*>(event),
-            (message_len <= UINT16_MAX) ? (uint16_t)message_len : UINT16_MAX);
+        rc = logbuf->Log(LOG_ID_EVENTS, now, uid, pid, tid, reinterpret_cast<char*>(event),
+                         (message_len <= UINT16_MAX) ? (uint16_t)message_len : UINT16_MAX);
         if (rc >= 0) {
             notify |= 1 << LOG_ID_EVENTS;
         }
@@ -328,9 +327,8 @@
         strncpy(newstr + 1 + str_len + prefix_len + suffix_len,
                 denial_metadata.c_str(), denial_metadata.length());
 
-        rc = logbuf->log(
-            LOG_ID_MAIN, now, uid, pid, tid, newstr,
-            (message_len <= UINT16_MAX) ? (uint16_t)message_len : UINT16_MAX);
+        rc = logbuf->Log(LOG_ID_MAIN, now, uid, pid, tid, newstr,
+                         (message_len <= UINT16_MAX) ? (uint16_t)message_len : UINT16_MAX);
 
         if (rc >= 0) {
             notify |= 1 << LOG_ID_MAIN;
diff --git a/logd/LogBuffer.h b/logd/LogBuffer.h
index efcd2af..887e5f0 100644
--- a/logd/LogBuffer.h
+++ b/logd/LogBuffer.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012-2014 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.
@@ -18,23 +18,12 @@
 
 #include <sys/types.h>
 
-#include <list>
-#include <optional>
-#include <string>
+#include <functional>
 
-#include <android/log.h>
-#include <private/android_filesystem_config.h>
+#include <log/log.h>
 #include <sysutils/SocketClient.h>
 
 #include "LogBufferElement.h"
-#include "LogStatistics.h"
-#include "LogTags.h"
-#include "LogWhiteBlackList.h"
-
-typedef std::list<LogBufferElement*> LogBufferElementCollection;
-
-class LogReaderList;
-class LogReaderThread;
 
 enum class FlushToResult {
     kSkip,
@@ -43,71 +32,23 @@
 };
 
 class LogBuffer {
-    LogBufferElementCollection mLogElements;
-    pthread_rwlock_t mLogElementsLock;
-
-    // watermark of any worst/chatty uid processing
-    typedef std::unordered_map<uid_t, LogBufferElementCollection::iterator>
-        LogBufferIteratorMap;
-    LogBufferIteratorMap mLastWorst[LOG_ID_MAX];
-    // watermark of any worst/chatty pid of system processing
-    typedef std::unordered_map<pid_t, LogBufferElementCollection::iterator>
-        LogBufferPidIteratorMap;
-    LogBufferPidIteratorMap mLastWorstPidOfSystem[LOG_ID_MAX];
-
-    unsigned long mMaxSize[LOG_ID_MAX];
-
-    LogBufferElement* lastLoggedElements[LOG_ID_MAX];
-    LogBufferElement* droppedElements[LOG_ID_MAX];
-    void log(LogBufferElement* elem);
-
   public:
-    LogBuffer(LogReaderList* reader_list, LogTags* tags, PruneList* prune, LogStatistics* stats);
-    ~LogBuffer();
-    void init();
+    virtual ~LogBuffer() {}
 
-    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);
+    virtual void Init() = 0;
+
+    virtual int Log(log_id_t log_id, log_time realtime, uid_t uid, pid_t pid, pid_t tid,
+                    const char* msg, uint16_t len) = 0;
     // lastTid is an optional context to help detect if the last previous
     // valid message was from the same source so we can differentiate chatty
     // filter types (identical or expired)
-    uint64_t flushTo(SocketClient* writer, uint64_t start,
-                     pid_t* lastTid,  // &lastTid[LOG_ID_MAX] or nullptr
-                     bool privileged, bool security,
-                     const std::function<FlushToResult(const LogBufferElement* element)>& filter);
+    virtual uint64_t FlushTo(
+            SocketClient* writer, uint64_t start,
+            pid_t* last_tid,  // nullable
+            bool privileged, bool security,
+            const std::function<FlushToResult(const LogBufferElement* element)>& filter) = 0;
 
-    bool clear(log_id_t id, uid_t uid = AID_ROOT);
-    unsigned long getSize(log_id_t id);
-    int setSize(log_id_t id, unsigned long size);
-
-  private:
-    void wrlock() {
-        pthread_rwlock_wrlock(&mLogElementsLock);
-    }
-    void rdlock() {
-        pthread_rwlock_rdlock(&mLogElementsLock);
-    }
-    void unlock() {
-        pthread_rwlock_unlock(&mLogElementsLock);
-    }
-
-    void maybePrune(log_id_t id);
-    void kickMe(LogReaderThread* me, log_id_t id, unsigned long pruneRows);
-
-    bool prune(log_id_t id, unsigned long pruneRows, uid_t uid = AID_ROOT);
-    LogBufferElementCollection::iterator erase(
-        LogBufferElementCollection::iterator it, bool coalesce = false);
-
-    // 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);
-
-    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];
-};
+    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;
+};
\ No newline at end of file
diff --git a/logd/LogBufferElement.cpp b/logd/LogBufferElement.cpp
index cc68ba4..32f641b 100644
--- a/logd/LogBufferElement.cpp
+++ b/logd/LogBufferElement.cpp
@@ -27,9 +27,9 @@
 #include <log/log_read.h>
 #include <private/android_logger.h>
 
-#include "LogBuffer.h"
 #include "LogCommand.h"
 #include "LogReader.h"
+#include "LogStatistics.h"
 #include "LogUtils.h"
 
 const uint64_t LogBufferElement::FLUSH_ERROR(0);
diff --git a/logd/LogBufferElement.h b/logd/LogBufferElement.h
index 8676cf1..3d0b65e 100644
--- a/logd/LogBufferElement.h
+++ b/logd/LogBufferElement.h
@@ -24,7 +24,6 @@
 #include <log/log.h>
 #include <sysutils/SocketClient.h>
 
-class LogBuffer;
 class LogStatistics;
 
 #define EXPIRE_HOUR_THRESHOLD 24  // Only expire chatty UID logs to preserve
@@ -34,8 +33,6 @@
 #define EXPIRE_RATELIMIT 10  // maximum rate in seconds to report expiration
 
 class __attribute__((packed)) LogBufferElement {
-    friend LogBuffer;
-
     // sized to match reality of incoming log packets
     const uint32_t mUid;
     const uint32_t mPid;
diff --git a/logd/LogKlog.cpp b/logd/LogKlog.cpp
index 5242dc3..1ea87a9 100644
--- a/logd/LogKlog.cpp
+++ b/logd/LogKlog.cpp
@@ -767,7 +767,7 @@
     }
 
     // Log message
-    int rc = logbuf->log(LOG_ID_KERNEL, now, uid, pid, tid, newstr, (uint16_t)n);
+    int rc = logbuf->Log(LOG_ID_KERNEL, now, uid, pid, tid, newstr, (uint16_t)n);
 
     return rc;
 }
diff --git a/logd/LogListener.cpp b/logd/LogListener.cpp
index 2057886..6880dbf 100644
--- a/logd/LogListener.cpp
+++ b/logd/LogListener.cpp
@@ -120,7 +120,7 @@
     // NB: hdr.msg_flags & MSG_TRUNC is not tested, silently passing a
     // truncated message to the logs.
 
-    logbuf_->log(logId, header->realtime, cred->uid, cred->pid, header->tid, msg,
+    logbuf_->Log(logId, header->realtime, cred->uid, cred->pid, header->tid, msg,
                  ((size_t)n <= UINT16_MAX) ? (uint16_t)n : UINT16_MAX);
 }
 
diff --git a/logd/LogReader.cpp b/logd/LogReader.cpp
index cc51542..6f91372 100644
--- a/logd/LogReader.cpp
+++ b/logd/LogReader.cpp
@@ -24,6 +24,7 @@
 #include <chrono>
 
 #include <cutils/sockets.h>
+#include <private/android_filesystem_config.h>
 #include <private/android_logger.h>
 
 #include "LogBuffer.h"
@@ -158,7 +159,7 @@
             return FlushToResult::kSkip;
         };
 
-        log_buffer_->flushTo(cli, sequence, nullptr, privileged, can_read_security, log_find_start);
+        log_buffer_->FlushTo(cli, sequence, nullptr, privileged, can_read_security, log_find_start);
 
         if (!start_time_set) {
             if (nonBlock) {
diff --git a/logd/LogReaderThread.cpp b/logd/LogReaderThread.cpp
index 4889c24..e58e3eb 100644
--- a/logd/LogReaderThread.cpp
+++ b/logd/LogReaderThread.cpp
@@ -84,13 +84,13 @@
         lock.unlock();
 
         if (tail_) {
-            logbuf.flushTo(client, start, nullptr, privileged_, can_read_security_logs_,
+            logbuf.FlushTo(client, start, nullptr, privileged_, can_read_security_logs_,
                            std::bind(&LogReaderThread::FilterFirstPass, this, _1));
             leading_dropped_ =
                     true;  // TODO: Likely a bug, if leading_dropped_ was not true before calling
                            // flushTo(), then it should not be reset to true after.
         }
-        start = logbuf.flushTo(client, start, last_tid_, privileged_, can_read_security_logs_,
+        start = logbuf.FlushTo(client, start, last_tid_, privileged_, can_read_security_logs_,
                                std::bind(&LogReaderThread::FilterSecondPass, this, _1));
 
         // We only ignore entries before the original start time for the first flushTo(), if we
diff --git a/logd/LogReaderThread.h b/logd/LogReaderThread.h
index ce59cbb..f828b6e 100644
--- a/logd/LogReaderThread.h
+++ b/logd/LogReaderThread.h
@@ -33,6 +33,7 @@
 
 class LogReader;
 class LogBufferElement;
+class LogReaderList;
 
 class LogReaderThread {
   public:
diff --git a/logd/fuzz/Android.bp b/logd/fuzz/Android.bp
index 299242d..f65fbdf 100644
--- a/logd/fuzz/Android.bp
+++ b/logd/fuzz/Android.bp
@@ -25,6 +25,7 @@
         "liblog",
         "liblogd",
         "libcutils",
+        "libsysutils",
     ],
     cflags: ["-Werror"],
 }
diff --git a/logd/fuzz/log_buffer_log_fuzzer.cpp b/logd/fuzz/log_buffer_log_fuzzer.cpp
index 3a18f25..8f90f50 100644
--- a/logd/fuzz/log_buffer_log_fuzzer.cpp
+++ b/logd/fuzz/log_buffer_log_fuzzer.cpp
@@ -15,7 +15,7 @@
  */
 #include <string>
 
-#include "../LogBuffer.h"
+#include "../ChattyLogBuffer.h"
 #include "../LogReaderList.h"
 #include "../LogReaderThread.h"
 #include "../LogStatistics.h"
@@ -72,7 +72,7 @@
 
     // Other elements not in enum.
     log_id_t log_id = static_cast<log_id_t>(unsigned(logInput->log_id) % (LOG_ID_MAX + 1));
-    log_buffer->log(log_id, logInput->realtime, logInput->uid, logInput->pid, logInput->tid, msg,
+    log_buffer->Log(log_id, logInput->realtime, logInput->uid, logInput->pid, logInput->tid, msg,
                     sizeof(uint32_t) + msg_length + 1);
     stats->Format(logInput->uid, logInput->pid, logInput->log_mask);
     *pdata = data;
@@ -100,21 +100,21 @@
     LogTags tags;
     PruneList prune_list;
     LogStatistics stats(true);
-    LogBuffer log_buffer(&reader_list, &tags, &prune_list, &stats);
+    LogBuffer* log_buffer = new ChattyLogBuffer(&reader_list, &tags, &prune_list, &stats);
     size_t data_left = size;
     const uint8_t** pdata = &data;
 
     prune_list.init(nullptr);
     // We want to get pruning code to get called.
-    log_id_for_each(i) { log_buffer.setSize(i, 10000); }
+    log_id_for_each(i) { log_buffer->SetSize(i, 10000); }
 
     while (data_left >= sizeof(LogInput) + 2 * sizeof(uint8_t)) {
-        if (!write_log_messages(pdata, &data_left, &log_buffer, &stats)) {
+        if (!write_log_messages(pdata, &data_left, log_buffer, &stats)) {
             return 0;
         }
     }
 
-    log_id_for_each(i) { log_buffer.clear(i); }
+    log_id_for_each(i) { log_buffer->Clear(i, 0); }
     return 0;
 }
 }  // namespace android
diff --git a/logd/main.cpp b/logd/main.cpp
index a7b89b8..6e1144b 100644
--- a/logd/main.cpp
+++ b/logd/main.cpp
@@ -47,6 +47,7 @@
 #include <processgroup/sched_policy.h>
 #include <utils/threads.h>
 
+#include "ChattyLogBuffer.h"
 #include "CommandListener.h"
 #include "LogAudit.h"
 #include "LogBuffer.h"
@@ -288,7 +289,7 @@
 
     // LogBuffer is the object which is responsible for holding all
     // log entries.
-    LogBuffer* logBuf = new LogBuffer(&reader_list, &log_tags, &prune_list, &log_statistics);
+    LogBuffer* logBuf = new ChattyLogBuffer(&reader_list, &log_tags, &prune_list, &log_statistics);
 
     // LogReader listens on /dev/socket/logdr. When a client
     // connects, log entries in the LogBuffer are written to the client.