diff --git a/adb/daemon/shell_service.cpp b/adb/daemon/shell_service.cpp
index fbfae1e..dbca4ad 100644
--- a/adb/daemon/shell_service.cpp
+++ b/adb/daemon/shell_service.cpp
@@ -646,15 +646,21 @@
         }
 
         // After handling all of the events we've received, check to see if any fds have died.
-        if (stdinout_pfd.revents & (POLLHUP | POLLRDHUP | POLLERR | POLLNVAL)) {
+        auto poll_finished = [](int events) {
+            // Don't return failure until we've read out all of the fd's incoming data.
+            return (events & POLLIN) == 0 &&
+                   (events & (POLLHUP | POLLRDHUP | POLLERR | POLLNVAL)) != 0;
+        };
+
+        if (poll_finished(stdinout_pfd.revents)) {
             return &stdinout_sfd_;
         }
 
-        if (stderr_pfd.revents & (POLLHUP | POLLRDHUP | POLLERR | POLLNVAL)) {
+        if (poll_finished(stderr_pfd.revents)) {
             return &stderr_sfd_;
         }
 
-        if (protocol_pfd.revents & (POLLHUP | POLLRDHUP | POLLERR | POLLNVAL)) {
+        if (poll_finished(protocol_pfd.revents)) {
             return &protocol_sfd_;
         }
     }  // while (!dead_sfd)
diff --git a/adb/daemon/usb.cpp b/adb/daemon/usb.cpp
index 7fff05a..a663871 100644
--- a/adb/daemon/usb.cpp
+++ b/adb/daemon/usb.cpp
@@ -231,7 +231,14 @@
                 offset += write_size;
             }
         }
-        SubmitWrites();
+
+        // Wake up the worker thread to submit writes.
+        uint64_t notify = 1;
+        ssize_t rc = adb_write(worker_event_fd_.get(), &notify, sizeof(notify));
+        if (rc < 0) {
+            PLOG(FATAL) << "failed to notify worker eventfd to submit writes";
+        }
+
         return true;
     }
 
@@ -443,6 +450,9 @@
                 }
 
                 ReadEvents();
+
+                std::lock_guard<std::mutex> lock(write_mutex_);
+                SubmitWrites();
             }
         });
     }
@@ -626,8 +636,6 @@
         write_requests_.erase(it);
         size_t outstanding_writes = --writes_submitted_;
         LOG(DEBUG) << "USB write: reaped, down to " << outstanding_writes;
-
-        SubmitWrites();
     }
 
     IoWriteBlock CreateWriteBlock(std::shared_ptr<Block> payload, size_t offset, size_t len,
diff --git a/adb/test_device.py b/adb/test_device.py
index f5e4cbb..9f1f403 100755
--- a/adb/test_device.py
+++ b/adb/test_device.py
@@ -82,10 +82,13 @@
 
 class AbbTest(DeviceTest):
     def test_smoke(self):
-        result = subprocess.run(['adb', 'abb'], capture_output=True)
-        self.assertEqual(1, result.returncode)
-        expected_output = b"cmd: No service specified; use -l to list all services\n"
-        self.assertEqual(expected_output, result.stderr)
+        abb = subprocess.run(['adb', 'abb'], capture_output=True)
+        cmd = subprocess.run(['adb', 'shell', 'cmd'], capture_output=True)
+
+        # abb squashes all failures to 1.
+        self.assertEqual(abb.returncode == 0, cmd.returncode == 0)
+        self.assertEqual(abb.stdout, cmd.stdout)
+        self.assertEqual(abb.stderr, cmd.stderr)
 
 class ForwardReverseTest(DeviceTest):
     def _test_no_rebind(self, description, direction_list, direction,
diff --git a/fs_mgr/fs_mgr.cpp b/fs_mgr/fs_mgr.cpp
index d2daaa1..8c2e001 100644
--- a/fs_mgr/fs_mgr.cpp
+++ b/fs_mgr/fs_mgr.cpp
@@ -454,7 +454,8 @@
                << entry.encryption_options;
         return;
     }
-    if ((options.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) != 0) {
+    if ((options.flags &
+         (FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64 | FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) != 0) {
         // We can only use this policy on ext4 if the "stable_inodes" feature
         // is set on the filesystem, otherwise shrinking will break encrypted files.
         if ((sb->s_feature_compat & cpu_to_le32(EXT4_FEATURE_COMPAT_STABLE_INODES)) == 0) {
diff --git a/fs_mgr/libsnapshot/Android.bp b/fs_mgr/libsnapshot/Android.bp
index 2783e4d..95301ff 100644
--- a/fs_mgr/libsnapshot/Android.bp
+++ b/fs_mgr/libsnapshot/Android.bp
@@ -248,10 +248,6 @@
 
 cc_defaults {
     name: "libsnapshot_fuzzer_defaults",
-
-    // TODO(b/154633114): make host supported.
-    // host_supported: true,
-
     native_coverage : true,
     srcs: [
         // Compile the protobuf definition again with type full.
diff --git a/logd/Android.bp b/logd/Android.bp
index 7e58f07..5e591d9 100644
--- a/logd/Android.bp
+++ b/logd/Android.bp
@@ -125,10 +125,7 @@
         "-Wextra",
         "-Werror",
         "-fno-builtin",
-
-        "-DAUDITD_LOG_TAG=1003",
-        "-DCHATTY_LOG_TAG=1004",
-    ],
+    ] + event_flag,
 
     srcs: [
         "logd_test.cpp",
diff --git a/logd/ChattyLogBuffer.cpp b/logd/ChattyLogBuffer.cpp
index 9e08e9d..fd2c236 100644
--- a/logd/ChattyLogBuffer.cpp
+++ b/logd/ChattyLogBuffer.cpp
@@ -28,6 +28,7 @@
 #include <time.h>
 #include <unistd.h>
 
+#include <limits>
 #include <unordered_map>
 #include <utility>
 
@@ -58,29 +59,17 @@
 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);
-
-    log_id_for_each(i) {
-        lastLoggedElements[i] = nullptr;
-        droppedElements[i] = nullptr;
-    }
-
     Init();
 }
 
-ChattyLogBuffer::~ChattyLogBuffer() {
-    log_id_for_each(i) {
-        delete lastLoggedElements[i];
-        delete droppedElements[i];
-    }
-}
+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) {
+    while (it != mLogElements.end() && it->getLogId() != log_id) {
         it++;
     }
     if (it != mLogElements.end()) {
@@ -146,33 +135,20 @@
     return SAME;
 }
 
-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;
-    }
-
-    // Slip the time by 1 nsec if the incoming lands on xxxxxx000 ns.
-    // This prevents any chance that an outside source can request an
-    // exact entry with time specified in ms or us precision.
-    if ((realtime.tv_nsec % 1000) == 0) ++realtime.tv_nsec;
-
-    LogBufferElement* elem = new LogBufferElement(log_id, realtime, uid, pid, tid, msg, len);
-
-    // b/137093665: don't coalesce security messages.
+bool ChattyLogBuffer::ShouldLog(log_id_t log_id, const char* msg, uint16_t len) {
     if (log_id == LOG_ID_SECURITY) {
-        wrlock();
-        log(elem);
-        unlock();
-
-        return len;
+        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) {
-        tag = tags_->tagToName(elem->getTag());
+        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);
         }
@@ -181,169 +157,112 @@
         tag = msg + 1;
         tag_len = strnlen(tag, len - 1);
     }
-    if (!__android_log_is_loggable_len(prio, tag, tag_len, ANDROID_LOG_VERBOSE)) {
+    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(elem);
-        delete elem;
+        stats_->AddTotal(log_id, len);
         return -EACCES;
     }
 
-    wrlock();
-    LogBufferElement* currentLast = lastLoggedElements[log_id];
-    if (currentLast) {
-        LogBufferElement* dropped = droppedElements[log_id];
-        uint16_t count = dropped ? dropped->getDropped() : 0;
-        //
-        // State Init
-        //     incoming:
-        //         dropped = nullptr
-        //         currentLast = nullptr;
-        //         elem = incoming message
-        //     outgoing:
-        //         dropped = nullptr -> State 0
-        //         currentLast = copy of elem
-        //         log elem
-        // State 0
-        //     incoming:
-        //         count = 0
-        //         dropped = nullptr
-        //         currentLast = copy of last message
-        //         elem = incoming message
-        //     outgoing: if match != DIFFERENT
-        //         dropped = copy of first identical message -> State 1
-        //         currentLast = reference to elem
-        //     break: if match == DIFFERENT
-        //         dropped = nullptr -> State 0
-        //         delete copy of last message (incoming currentLast)
-        //         currentLast = copy of elem
-        //         log elem
-        // State 1
-        //     incoming:
-        //         count = 0
-        //         dropped = copy of first identical message
-        //         currentLast = reference to last held-back incoming
-        //                       message
-        //         elem = incoming message
-        //     outgoing: if match == SAME
-        //         delete copy of first identical message (dropped)
-        //         dropped = reference to last held-back incoming
-        //                   message set to chatty count of 1 -> State 2
-        //         currentLast = reference to elem
-        //     outgoing: if match == SAME_LIBLOG
-        //         dropped = copy of first identical message -> State 1
-        //         take sum of currentLast and elem
-        //         if sum overflows:
-        //             log currentLast
-        //             currentLast = reference to elem
-        //         else
-        //             delete currentLast
-        //             currentLast = reference to elem, sum liblog.
-        //     break: if match == DIFFERENT
-        //         delete dropped
-        //         dropped = nullptr -> State 0
-        //         log reference to last held-back (currentLast)
-        //         currentLast = copy of elem
-        //         log elem
-        // State 2
-        //     incoming:
-        //         count = chatty count
-        //         dropped = chatty message holding count
-        //         currentLast = reference to last held-back incoming
-        //                       message.
-        //         dropped = chatty message holding count
-        //         elem = incoming message
-        //     outgoing: if match != DIFFERENT
-        //         delete chatty message holding count
-        //         dropped = reference to last held-back incoming
-        //                   message, set to chatty count + 1
-        //         currentLast = reference to elem
-        //     break: if match == DIFFERENT
-        //         log dropped (chatty message)
-        //         dropped = nullptr -> State 0
-        //         log reference to last held-back (currentLast)
-        //         currentLast = copy of elem
-        //         log elem
-        //
-        enum match_type match = identical(elem, currentLast);
-        if (match != DIFFERENT) {
-            if (dropped) {
-                // Sum up liblog tag messages?
-                if ((count == 0) /* at Pass 1 */ && (match == SAME_LIBLOG)) {
-                    android_log_event_int_t* event = reinterpret_cast<android_log_event_int_t*>(
-                            const_cast<char*>(currentLast->getMsg()));
-                    //
-                    // To unit test, differentiate with something like:
-                    //    event->header.tag = htole32(CHATTY_LOG_TAG);
-                    // here, then instead of delete currentLast below,
-                    // log(currentLast) to see the incremental sums form.
-                    //
-                    uint32_t swab = event->payload.data;
-                    unsigned long long total = htole32(swab);
-                    event = reinterpret_cast<android_log_event_int_t*>(
-                            const_cast<char*>(elem->getMsg()));
-                    swab = event->payload.data;
+    // 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;
 
-                    lastLoggedElements[LOG_ID_EVENTS] = elem;
-                    total += htole32(swab);
-                    // check for overflow
-                    if (total >= UINT32_MAX) {
-                        log(currentLast);
-                        unlock();
-                        return len;
-                    }
-                    stats_->AddTotal(currentLast);
-                    delete currentLast;
-                    swab = total;
-                    event->payload.data = htole32(swab);
-                    unlock();
-                    return len;
-                }
-                if (count == USHRT_MAX) {
-                    log(dropped);
-                    count = 1;
-                } else {
-                    delete dropped;
-                    ++count;
-                }
+    LogBufferElement elem(log_id, realtime, uid, pid, tid, msg, len);
+
+    // 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;
+    }
+
+    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;
+    }
+
+    LogBufferElement& current_last = *last_logged_elements_[log_id];
+    enum match_type match = identical(&elem, &current_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]));
             }
-            if (count) {
-                stats_->AddTotal(currentLast);
-                currentLast->setDropped(count);
-            }
-            droppedElements[log_id] = currentLast;
-            lastLoggedElements[log_id] = elem;
-            unlock();
+            duplicate_elements_[log_id].reset();
+            // Log the saved copy of the last identical message seen.
+            Log(std::move(current_last));
+        }
+        last_logged_elements_[log_id].emplace(elem);
+        Log(std::move(elem));
+        return len;
+    }
+
+    // 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;
+    }
+
+    // 3+ identical LIBLOG event messages: coalesce them into last_logged_elements_.
+    if (match == SAME_LIBLOG) {
+        const android_log_event_int_t* current_last_event =
+                reinterpret_cast<const android_log_event_int_t*>(current_last.getMsg());
+        int64_t current_last_count = current_last_event->payload.data;
+        android_log_event_int_t* elem_event =
+                reinterpret_cast<android_log_event_int_t*>(const_cast<char*>(elem.getMsg()));
+        int64_t elem_count = elem_event->payload.data;
+
+        int64_t total = current_last_count + elem_count;
+        if (total > std::numeric_limits<int32_t>::max()) {
+            Log(std::move(current_last));
+            last_logged_elements_[log_id].emplace(std::move(elem));
             return len;
         }
-        if (dropped) {         // State 1 or 2
-            if (count) {       // State 2
-                log(dropped);  // report chatty
-            } else {           // State 1
-                delete dropped;
-            }
-            droppedElements[log_id] = nullptr;
-            log(currentLast);  // report last message in the series
-        } else {               // State 0
-            delete currentLast;
-        }
+        stats_->AddTotal(current_last.getLogId(), current_last.getMsgLen());
+        elem_event->payload.data = total;
+        last_logged_elements_[log_id].emplace(std::move(elem));
+        return len;
     }
-    lastLoggedElements[log_id] = new LogBufferElement(*elem);
 
-    log(elem);
-    unlock();
-
+    // 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]));
+        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());
+    // 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;
 }
 
-// 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());
+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);
 }
 
-// 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)) {
@@ -353,15 +272,15 @@
 
 LogBufferElementCollection::iterator ChattyLogBuffer::erase(LogBufferElementCollection::iterator it,
                                                             bool coalesce) {
-    LogBufferElement* element = *it;
-    log_id_t id = element->getLogId();
+    LogBufferElement& element = *it;
+    log_id_t id = element.getLogId();
 
     // Remove iterator references in the various lists that will become stale
     // after the element is erased from the main logging list.
 
     {  // start of scope for found iterator
-        int key = (id == LOG_ID_EVENTS || id == LOG_ID_SECURITY) ? element->getTag()
-                                                                 : element->getUid();
+        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);
@@ -372,7 +291,7 @@
         // 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());
+        LogBufferPidIteratorMap::iterator found = mLastWorstPidOfSystem[id].find(element.getPid());
         if (found != mLastWorstPidOfSystem[id].end() && it == found->second) {
             mLastWorstPidOfSystem[id].erase(found);
         }
@@ -386,7 +305,15 @@
     int key =
             (id == LOG_ID_EVENTS || id == LOG_ID_SECURITY) ? element->getTag() : element->getUid();
 #endif
+
+    if (coalesce) {
+        stats_->Erase(&element);
+    } else {
+        stats_->Subtract(&element);
+    }
+
     it = mLogElements.erase(it);
+
     if (doSetLast) {
         log_id_for_each(i) {
             if (setLast[i]) {
@@ -413,13 +340,6 @@
         }
     }
 #endif
-    if (coalesce) {
-        stats_->Erase(element);
-    } else {
-        stats_->Subtract(element);
-    }
-    delete element;
-
     return it;
 }
 
@@ -539,8 +459,6 @@
 // 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.
 //
-// ChattyLogBuffer::wrlock() must be held when this function is called.
-//
 bool ChattyLogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) {
     LogReaderThread* oldest = nullptr;
     bool busy = false;
@@ -567,14 +485,14 @@
         // filter logistics is not required.
         it = GetOldest(id);
         while (it != mLogElements.end()) {
-            LogBufferElement* element = *it;
+            LogBufferElement& element = *it;
 
-            if (element->getLogId() != id || element->getUid() != caller_uid) {
+            if (element.getLogId() != id || element.getUid() != caller_uid) {
                 ++it;
                 continue;
             }
 
-            if (oldest && oldest->start() <= element->getSequence()) {
+            if (oldest && oldest->start() <= element.getSequence()) {
                 busy = true;
                 kickMe(oldest, id, pruneRows);
                 break;
@@ -654,21 +572,21 @@
         --lastt;
         LogBufferElementLast last;
         while (it != mLogElements.end()) {
-            LogBufferElement* element = *it;
+            LogBufferElement& element = *it;
 
-            if (oldest && oldest->start() <= element->getSequence()) {
+            if (oldest && oldest->start() <= element.getSequence()) {
                 busy = true;
                 // Do not let chatty eliding trigger any reader mitigation
                 break;
             }
 
-            if (element->getLogId() != id) {
+            if (element.getLogId() != id) {
                 ++it;
                 continue;
             }
             // below this point element->getLogId() == id
 
-            uint16_t dropped = element->getDropped();
+            uint16_t dropped = element.getDropped();
 
             // remove any leading drops
             if (leading && dropped) {
@@ -676,16 +594,16 @@
                 continue;
             }
 
-            if (dropped && last.coalesce(element, dropped)) {
+            if (dropped && last.coalesce(&element, dropped)) {
                 it = erase(it, true);
                 continue;
             }
 
-            int key = (id == LOG_ID_EVENTS || id == LOG_ID_SECURITY) ? element->getTag()
-                                                                     : element->getUid();
+            int key = (id == LOG_ID_EVENTS || id == LOG_ID_SECURITY) ? element.getTag()
+                                                                     : element.getUid();
 
-            if (hasBlacklist && prune_->naughty(element)) {
-                last.clear(element);
+            if (hasBlacklist && prune_->naughty(&element)) {
+                last.clear(&element);
                 it = erase(it);
                 if (dropped) {
                     continue;
@@ -701,25 +619,25 @@
                     if (worst_sizes < second_worst_sizes) {
                         break;
                     }
-                    worst_sizes -= element->getMsgLen();
+                    worst_sizes -= element.getMsgLen();
                 }
                 continue;
             }
 
-            if ((element->getRealTime() < ((*lastt)->getRealTime() - too_old)) ||
-                (element->getRealTime() > (*lastt)->getRealTime())) {
+            if (element.getRealTime() < (lastt->getRealTime() - too_old) ||
+                element.getRealTime() > lastt->getRealTime()) {
                 break;
             }
 
             if (dropped) {
-                last.add(element);
-                if (worstPid && ((!gc && element->getPid() == worstPid) ||
-                                 mLastWorstPidOfSystem[id].find(element->getPid()) ==
+                last.add(&element);
+                if (worstPid && ((!gc && element.getPid() == worstPid) ||
+                                 mLastWorstPidOfSystem[id].find(element.getPid()) ==
                                          mLastWorstPidOfSystem[id].end())) {
                     // element->getUid() may not be AID_SYSTEM, next best
                     // watermark if current one empty. id is not LOG_ID_EVENTS
                     // or LOG_ID_SECURITY because of worstPid check.
-                    mLastWorstPidOfSystem[id][element->getPid()] = it;
+                    mLastWorstPidOfSystem[id][element.getPid()] = it;
                 }
                 if ((!gc && !worstPid && (key == worst)) ||
                     (mLastWorst[id].find(key) == mLastWorst[id].end())) {
@@ -729,9 +647,9 @@
                 continue;
             }
 
-            if (key != worst || (worstPid && element->getPid() != worstPid)) {
+            if (key != worst || (worstPid && element.getPid() != worstPid)) {
                 leading = false;
-                last.clear(element);
+                last.clear(&element);
                 ++it;
                 continue;
             }
@@ -745,18 +663,18 @@
 
             kick = true;
 
-            uint16_t len = element->getMsgLen();
+            uint16_t len = element.getMsgLen();
 
             // do not create any leading drops
             if (leading) {
                 it = erase(it);
             } else {
-                stats_->Drop(element);
-                element->setDropped(1);
-                if (last.coalesce(element, 1)) {
+                stats_->Drop(&element);
+                element.setDropped(1);
+                if (last.coalesce(&element, 1)) {
                     it = erase(it, true);
                 } else {
-                    last.add(element);
+                    last.add(&element);
                     if (worstPid && (!gc || mLastWorstPidOfSystem[id].find(worstPid) ==
                                                     mLastWorstPidOfSystem[id].end())) {
                         // element->getUid() may not be AID_SYSTEM, next best
@@ -786,20 +704,20 @@
     bool hasWhitelist = (id != LOG_ID_SECURITY) && prune_->nice() && !clearAll;
     it = GetOldest(id);
     while ((pruneRows > 0) && (it != mLogElements.end())) {
-        LogBufferElement* element = *it;
+        LogBufferElement& element = *it;
 
-        if (element->getLogId() != id) {
+        if (element.getLogId() != id) {
             it++;
             continue;
         }
 
-        if (oldest && oldest->start() <= element->getSequence()) {
+        if (oldest && oldest->start() <= element.getSequence()) {
             busy = true;
             if (!whitelist) kickMe(oldest, id, pruneRows);
             break;
         }
 
-        if (hasWhitelist && !element->getDropped() && prune_->nice(element)) {
+        if (hasWhitelist && !element.getDropped() && prune_->nice(&element)) {
             // WhiteListed
             whitelist = true;
             it++;
@@ -814,14 +732,14 @@
     if (whitelist && (pruneRows > 0)) {
         it = GetOldest(id);
         while ((it != mLogElements.end()) && (pruneRows > 0)) {
-            LogBufferElement* element = *it;
+            LogBufferElement& element = *it;
 
-            if (element->getLogId() != id) {
+            if (element.getLogId() != id) {
                 ++it;
                 continue;
             }
 
-            if (oldest && oldest->start() <= element->getSequence()) {
+            if (oldest && oldest->start() <= element.getSequence()) {
                 busy = true;
                 kickMe(oldest, id, pruneRows);
                 break;
@@ -845,9 +763,10 @@
             // one entry, not another clear run, so we are looking for
             // the quick side effect of the return value to tell us if
             // we have a _blocked_ reader.
-            wrlock();
-            busy = prune(id, 1, uid);
-            unlock();
+            {
+                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
@@ -864,9 +783,10 @@
                 }
             }
         }
-        wrlock();
-        busy = prune(id, ULONG_MAX, uid);
-        unlock();
+        {
+            auto lock = std::lock_guard{lock_};
+            busy = prune(id, ULONG_MAX, uid);
+        }
         if (!busy || !--retry) {
             break;
         }
@@ -881,17 +801,15 @@
     if (!__android_logger_valid_buffer_size(size)) {
         return -1;
     }
-    wrlock();
+    auto lock = std::lock_guard{lock_};
     log_buffer_size(id) = size;
-    unlock();
     return 0;
 }
 
 // get the total space allocated to "id"
 unsigned long ChattyLogBuffer::GetSize(log_id_t id) {
-    rdlock();
+    auto shared_lock = SharedLock{lock_};
     size_t retval = log_buffer_size(id);
-    unlock();
     return retval;
 }
 
@@ -901,7 +819,7 @@
     LogBufferElementCollection::iterator it;
     uid_t uid = writer->uid();
 
-    rdlock();
+    auto shared_lock = SharedLock{lock_};
 
     if (start <= 1) {
         // client wants to start from the beginning
@@ -912,8 +830,7 @@
         for (it = mLogElements.end(); it != mLogElements.begin();
              /* do nothing */) {
             --it;
-            LogBufferElement* element = *it;
-            if (element->getSequence() <= start) {
+            if (it->getSequence() <= start) {
                 it++;
                 break;
             }
@@ -923,19 +840,19 @@
     uint64_t curr = start;
 
     for (; it != mLogElements.end(); ++it) {
-        LogBufferElement* element = *it;
+        LogBufferElement& element = *it;
 
-        if (!writer->privileged() && element->getUid() != uid) {
+        if (!writer->privileged() && element.getUid() != uid) {
             continue;
         }
 
-        if (!writer->can_read_security_logs() && element->getLogId() == LOG_ID_SECURITY) {
+        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);
+            FlushToResult ret = filter(&element);
             if (ret == FlushToResult::kSkip) {
                 continue;
             }
@@ -946,27 +863,24 @@
 
         bool sameTid = false;
         if (lastTid) {
-            sameTid = lastTid[element->getLogId()] == element->getTid();
+            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();
+            lastTid[element.getLogId()] = (element.getDropped() && !sameTid) ? 0 : element.getTid();
         }
 
-        unlock();
+        shared_lock.unlock();
 
-        curr = element->getSequence();
+        curr = element.getSequence();
         // range locking in LastLogTimes looks after us
-        if (!element->FlushTo(writer, stats_, sameTid)) {
+        if (!element.FlushTo(writer, stats_, sameTid)) {
             return FLUSH_ERROR;
         }
 
-        rdlock();
+        shared_lock.lock_shared();
     }
-    unlock();
-
     return curr;
 }
diff --git a/logd/ChattyLogBuffer.h b/logd/ChattyLogBuffer.h
index 29a421d..08c4bff 100644
--- a/logd/ChattyLogBuffer.h
+++ b/logd/ChattyLogBuffer.h
@@ -22,6 +22,7 @@
 #include <optional>
 #include <string>
 
+#include <android-base/thread_annotations.h>
 #include <android/log.h>
 #include <private/android_filesystem_config.h>
 #include <sysutils/SocketClient.h>
@@ -34,25 +35,21 @@
 #include "LogTags.h"
 #include "LogWhiteBlackList.h"
 #include "LogWriter.h"
+#include "rwlock.h"
 
-typedef std::list<LogBufferElement*> LogBufferElementCollection;
+typedef std::list<LogBufferElement> LogBufferElementCollection;
 
 class ChattyLogBuffer : public LogBuffer {
-    LogBufferElementCollection mLogElements;
-    pthread_rwlock_t mLogElementsLock;
+    LogBufferElementCollection mLogElements GUARDED_BY(lock_);
 
     // watermark of any worst/chatty uid processing
     typedef std::unordered_map<uid_t, LogBufferElementCollection::iterator> LogBufferIteratorMap;
-    LogBufferIteratorMap mLastWorst[LOG_ID_MAX];
+    LogBufferIteratorMap mLastWorst[LOG_ID_MAX] GUARDED_BY(lock_);
     // watermark of any worst/chatty pid of system processing
     typedef std::unordered_map<pid_t, LogBufferElementCollection::iterator> LogBufferPidIteratorMap;
-    LogBufferPidIteratorMap mLastWorstPidOfSystem[LOG_ID_MAX];
+    LogBufferPidIteratorMap mLastWorstPidOfSystem[LOG_ID_MAX] GUARDED_BY(lock_);
 
-    unsigned long mMaxSize[LOG_ID_MAX];
-
-    LogBufferElement* lastLoggedElements[LOG_ID_MAX];
-    LogBufferElement* droppedElements[LOG_ID_MAX];
-    void log(LogBufferElement* elem);
+    unsigned long mMaxSize[LOG_ID_MAX] GUARDED_BY(lock_);
 
   public:
     ChattyLogBuffer(LogReaderList* reader_list, LogTags* tags, PruneList* prune,
@@ -71,20 +68,18 @@
     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) REQUIRES(lock_);
+    void kickMe(LogReaderThread* me, log_id_t id, unsigned long pruneRows) REQUIRES_SHARED(lock_);
 
-    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);
+    bool prune(log_id_t id, unsigned long pruneRows, uid_t uid = AID_ROOT) REQUIRES(lock_);
     LogBufferElementCollection::iterator erase(LogBufferElementCollection::iterator it,
-                                               bool coalesce = false);
+                                               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);
+    LogBufferElementCollection::iterator GetOldest(log_id_t log_id) REQUIRES(lock_);
 
     LogReaderList* reader_list_;
     LogTags* tags_;
@@ -94,4 +89,12 @@
     // 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_);
+    // This contains an element if duplicate messages are seen.
+    // Its `dropped` count is `duplicates seen - 1`.
+    std::optional<LogBufferElement> duplicate_elements_[LOG_ID_MAX] GUARDED_BY(lock_);
 };
diff --git a/logd/LogBufferElement.cpp b/logd/LogBufferElement.cpp
index 4f5cabd..3bcf11d 100644
--- a/logd/LogBufferElement.cpp
+++ b/logd/LogBufferElement.cpp
@@ -63,6 +63,23 @@
     }
 }
 
+LogBufferElement::LogBufferElement(LogBufferElement&& elem)
+    : mUid(elem.mUid),
+      mPid(elem.mPid),
+      mTid(elem.mTid),
+      mSequence(elem.mSequence),
+      mRealTime(elem.mRealTime),
+      mMsgLen(elem.mMsgLen),
+      mLogId(elem.mLogId),
+      mDropped(elem.mDropped) {
+    if (mDropped) {
+        mTag = elem.getTag();
+    } else {
+        mMsg = elem.mMsg;
+        elem.mMsg = nullptr;
+    }
+}
+
 LogBufferElement::~LogBufferElement() {
     if (!mDropped) {
         delete[] mMsg;
diff --git a/logd/LogBufferElement.h b/logd/LogBufferElement.h
index 2f2d70d..a777970 100644
--- a/logd/LogBufferElement.h
+++ b/logd/LogBufferElement.h
@@ -60,6 +60,7 @@
     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(const LogBufferElement& elem);
+    LogBufferElement(LogBufferElement&& elem);
     ~LogBufferElement();
 
     bool isBinary(void) const {
diff --git a/logd/LogBufferTest.cpp b/logd/LogBufferTest.cpp
index cc3cb76..b52ce8f 100644
--- a/logd/LogBufferTest.cpp
+++ b/logd/LogBufferTest.cpp
@@ -18,7 +18,9 @@
 
 #include <unistd.h>
 
+#include <limits>
 #include <memory>
+#include <regex>
 #include <vector>
 
 #include <android-base/stringprintf.h>
@@ -34,6 +36,7 @@
 #include "LogWriter.h"
 
 using android::base::Join;
+using android::base::Split;
 using android::base::StringPrintf;
 
 #ifndef __ANDROID__
@@ -58,12 +61,148 @@
     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) {
+    std::vector<std::string> errors;
+    if (!ignore_len && expected.len != result.len) {
+        errors.emplace_back(
+                StringPrintf("len: expected %" PRIu16 " vs %" PRIu16, expected.len, result.len));
+    }
+    if (expected.hdr_size != result.hdr_size) {
+        errors.emplace_back(StringPrintf("hdr_size: %" PRIu16 " vs %" PRIu16, expected.hdr_size,
+                                         result.hdr_size));
+    }
+    if (expected.pid != result.pid) {
+        errors.emplace_back(
+                StringPrintf("pid: expected %" PRIi32 " vs %" PRIi32, expected.pid, result.pid));
+    }
+    if (expected.tid != result.tid) {
+        errors.emplace_back(
+                StringPrintf("tid: expected %" PRIu32 " vs %" PRIu32, expected.tid, result.tid));
+    }
+    if (expected.sec != result.sec) {
+        errors.emplace_back(
+                StringPrintf("sec: expected %" PRIu32 " vs %" PRIu32, expected.sec, result.sec));
+    }
+    if (expected.nsec != result.nsec) {
+        errors.emplace_back(
+                StringPrintf("nsec: expected %" PRIu32 " vs %" PRIu32, expected.nsec, result.nsec));
+    }
+    if (expected.lid != result.lid) {
+        errors.emplace_back(
+                StringPrintf("lid: expected %" PRIu32 " vs %" PRIu32, expected.lid, result.lid));
+    }
+    if (expected.uid != result.uid) {
+        errors.emplace_back(
+                StringPrintf("uid: expected %" PRIu32 " vs %" PRIu32, expected.uid, result.uid));
+    }
+    return errors;
+}
+
+std::string MakePrintable(std::string in) {
+    if (in.size() > 80) {
+        in = in.substr(0, 80) + "...";
+    }
+    std::string result;
+    for (const char c : in) {
+        if (isprint(c)) {
+            result.push_back(c);
+        } else {
+            result.append(StringPrintf("\\%02x", static_cast<int>(c) & 0xFF));
+        }
+    }
+    return result;
+}
+
+std::string CompareMessages(const std::string& expected, const std::string& result) {
+    if (expected == result) {
+        return {};
+    }
+    size_t diff_index = 0;
+    for (; diff_index < std::min(expected.size(), result.size()); ++diff_index) {
+        if (expected[diff_index] != result[diff_index]) {
+            break;
+        }
+    }
+
+    if (diff_index < 10) {
+        auto expected_short = MakePrintable(expected);
+        auto result_short = MakePrintable(result);
+        return StringPrintf("msg: expected '%s' vs '%s'", expected_short.c_str(),
+                            result_short.c_str());
+    }
+
+    auto expected_short = MakePrintable(expected.substr(diff_index));
+    auto result_short = MakePrintable(result.substr(diff_index));
+    return StringPrintf("msg: index %zu: expected '%s' vs '%s'", diff_index, expected_short.c_str(),
+                        result_short.c_str());
+}
+
+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));
+
+    if (expected_pieces.size() != 3 || result_pieces.size() != 3) {
+        return StringPrintf(
+                "msg: should have 3 null delimited strings found %d in expected, %d in result: "
+                "'%s' vs '%s'",
+                static_cast<int>(expected_pieces.size()), static_cast<int>(result_pieces.size()),
+                MakePrintable(expected).c_str(), MakePrintable(result).c_str());
+    }
+    if (expected_pieces[0] != result_pieces[0]) {
+        return StringPrintf("msg: tag/priority mismatch expected '%s' vs '%s'",
+                            MakePrintable(expected_pieces[0]).c_str(),
+                            MakePrintable(result_pieces[0]).c_str());
+    }
+    std::regex expected_tag_regex(expected_pieces[1]);
+    if (!std::regex_search(result_pieces[1], expected_tag_regex)) {
+        return StringPrintf("msg: message regex mismatch expected '%s' vs '%s'",
+                            MakePrintable(expected_pieces[1]).c_str(),
+                            MakePrintable(result_pieces[1]).c_str());
+    }
+    if (expected_pieces[2] != result_pieces[2]) {
+        return StringPrintf("msg: nothing expected after final null character '%s' vs '%s'",
+                            MakePrintable(expected_pieces[2]).c_str(),
+                            MakePrintable(result_pieces[2]).c_str());
+    }
+    return {};
+}
+
+void CompareLogMessages(const std::vector<LogMessage>& expected,
+                        const std::vector<LogMessage>& result) {
+    EXPECT_EQ(expected.size(), result.size());
+    size_t end = std::min(expected.size(), result.size());
+    size_t num_errors = 0;
+    for (size_t i = 0; i < end; ++i) {
+        auto errors =
+                CompareLoggerEntries(expected[i].entry, result[i].entry, expected[i].regex_compare);
+        auto msg_error = expected[i].regex_compare
+                                 ? CompareRegexMessages(expected[i].message, result[i].message)
+                                 : CompareMessages(expected[i].message, result[i].message);
+        if (!msg_error.empty()) {
+            errors.emplace_back(msg_error);
+        }
+        if (!errors.empty()) {
+            GTEST_LOG_(ERROR) << "Mismatch log message " << i << "\n" << Join(errors, "\n");
+            ++num_errors;
+        }
+    }
+    EXPECT_EQ(0U, num_errors);
+}
+
 class TestWriter : public LogWriter {
   public:
-    TestWriter(std::vector<std::pair<logger_entry, std::string>>* msgs, bool* released)
+    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(entry, std::string(message, entry.len));
+        msgs_->emplace_back(LogMessage{entry, std::string(message, entry.len), false});
         return true;
     }
 
@@ -74,7 +213,7 @@
     std::string name() const override { return "test_writer"; }
 
   private:
-    std::vector<std::pair<logger_entry, std::string>>* msgs_;
+    std::vector<LogMessage>* msgs_;
     bool* released_;
 };
 
@@ -84,107 +223,20 @@
         log_buffer_.reset(new ChattyLogBuffer(&reader_list_, &tags_, &prune_, &stats_));
     }
 
-    void FixupMessages(std::vector<std::pair<logger_entry, std::string>>* messages) {
-        for (auto& [entry, message] : *messages) {
+    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<std::pair<logger_entry, std::string>>& messages) {
-        for (auto& [entry, message] : messages) {
+    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());
         }
     }
 
-    std::vector<std::string> CompareLoggerEntries(const logger_entry& expected,
-                                                  const logger_entry& result) {
-        std::vector<std::string> errors;
-        if (expected.len != result.len) {
-            errors.emplace_back(
-                    StringPrintf("len: %" PRIu16 " vs %" PRIu16, expected.len, result.len));
-        }
-        if (expected.hdr_size != result.hdr_size) {
-            errors.emplace_back(StringPrintf("hdr_size: %" PRIu16 " vs %" PRIu16, expected.hdr_size,
-                                             result.hdr_size));
-        }
-        if (expected.pid != result.pid) {
-            errors.emplace_back(
-                    StringPrintf("pid: %" PRIi32 " vs %" PRIi32, expected.pid, result.pid));
-        }
-        if (expected.tid != result.tid) {
-            errors.emplace_back(
-                    StringPrintf("tid: %" PRIu32 " vs %" PRIu32, expected.tid, result.tid));
-        }
-        if (expected.sec != result.sec) {
-            errors.emplace_back(
-                    StringPrintf("sec: %" PRIu32 " vs %" PRIu32, expected.sec, result.sec));
-        }
-        if (expected.nsec != result.nsec) {
-            errors.emplace_back(
-                    StringPrintf("nsec: %" PRIu32 " vs %" PRIu32, expected.nsec, result.nsec));
-        }
-        if (expected.lid != result.lid) {
-            errors.emplace_back(
-                    StringPrintf("lid: %" PRIu32 " vs %" PRIu32, expected.lid, result.lid));
-        }
-        if (expected.uid != result.uid) {
-            errors.emplace_back(
-                    StringPrintf("uid: %" PRIu32 " vs %" PRIu32, expected.uid, result.uid));
-        }
-        return errors;
-    }
-
-    std::string CompareMessages(const std::string& expected, const std::string& result) {
-        if (expected == result) {
-            return {};
-        }
-        auto shorten_string = [](const std::string& in) {
-            if (in.size() > 10) {
-                return in.substr(0, 10) + "...";
-            }
-            return in;
-        };
-
-        size_t diff_index = 0;
-        for (; diff_index < std::min(expected.size(), result.size()); ++diff_index) {
-            if (expected[diff_index] != result[diff_index]) {
-                break;
-            }
-        }
-
-        if (diff_index < 10) {
-            auto expected_short = shorten_string(expected);
-            auto result_short = shorten_string(result);
-            return StringPrintf("msg: %s vs %s", expected_short.c_str(), result_short.c_str());
-        }
-
-        auto expected_short = shorten_string(expected.substr(diff_index));
-        auto result_short = shorten_string(result.substr(diff_index));
-        return StringPrintf("msg: index %zu: %s vs %s", diff_index, expected_short.c_str(),
-                            result_short.c_str());
-    }
-
-    void CompareLogMessages(const std::vector<std::pair<logger_entry, std::string>>& expected,
-                            const std::vector<std::pair<logger_entry, std::string>>& result) {
-        EXPECT_EQ(expected.size(), result.size());
-        size_t end = std::min(expected.size(), result.size());
-        size_t num_errors = 0;
-        for (size_t i = 0; i < end; ++i) {
-            auto errors = CompareLoggerEntries(expected[i].first, result[i].first);
-            auto msg_error = CompareMessages(expected[i].second, result[i].second);
-            if (!msg_error.empty()) {
-                errors.emplace_back(msg_error);
-            }
-            if (!errors.empty()) {
-                GTEST_LOG_(ERROR) << "Mismatch log message " << i << " " << Join(errors, " ");
-                ++num_errors;
-            }
-        }
-        EXPECT_EQ(0U, num_errors);
-    }
-
     LogReaderList reader_list_;
     LogTags tags_;
     PruneList prune_;
@@ -193,7 +245,7 @@
 };
 
 TEST_F(LogBufferTest, smoke) {
-    std::vector<std::pair<logger_entry, std::string>> log_messages = {
+    std::vector<LogMessage> log_messages = {
             {{
                      .pid = 1,
                      .tid = 1,
@@ -207,7 +259,7 @@
     FixupMessages(&log_messages);
     LogMessages(log_messages);
 
-    std::vector<std::pair<logger_entry, std::string>> read_log_messages;
+    std::vector<LogMessage> read_log_messages;
     std::unique_ptr<LogWriter> test_writer(new TestWriter(&read_log_messages, nullptr));
     uint64_t flush_result = log_buffer_->FlushTo(test_writer.get(), 1, nullptr, nullptr);
     EXPECT_EQ(1ULL, flush_result);
@@ -215,7 +267,7 @@
 }
 
 TEST_F(LogBufferTest, smoke_with_reader_thread) {
-    std::vector<std::pair<logger_entry, std::string>> log_messages = {
+    std::vector<LogMessage> log_messages = {
             {{.pid = 1, .tid = 2, .sec = 10000, .nsec = 20001, .lid = LOG_ID_MAIN, .uid = 0},
              "first"},
             {{.pid = 10, .tid = 2, .sec = 10000, .nsec = 20002, .lid = LOG_ID_MAIN, .uid = 0},
@@ -240,7 +292,7 @@
     FixupMessages(&log_messages);
     LogMessages(log_messages);
 
-    std::vector<std::pair<logger_entry, std::string>> read_log_messages;
+    std::vector<LogMessage> read_log_messages;
     bool released = false;
 
     {
@@ -264,7 +316,7 @@
 
 // Generate random messages, set the 'sec' parameter explicit though, to be able to track the
 // expected order of messages.
-std::pair<logger_entry, std::string> GenerateRandomLogMessage(uint32_t sec) {
+LogMessage GenerateRandomLogMessage(uint32_t sec) {
     auto rand_uint32 = [](int max) -> uint32_t { return rand() % max; };
     logger_entry entry = {
             .hdr_size = sizeof(logger_entry),
@@ -308,13 +360,13 @@
 
 TEST_F(LogBufferTest, random_messages) {
     srand(1);
-    std::vector<std::pair<logger_entry, std::string>> log_messages;
+    std::vector<LogMessage> log_messages;
     for (size_t i = 0; i < 1000; ++i) {
         log_messages.emplace_back(GenerateRandomLogMessage(i));
     }
     LogMessages(log_messages);
 
-    std::vector<std::pair<logger_entry, std::string>> read_log_messages;
+    std::vector<LogMessage> read_log_messages;
     bool released = false;
 
     {
@@ -335,3 +387,184 @@
     }
     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
diff --git a/logd/LogStatistics.cpp b/logd/LogStatistics.cpp
index 14bcb63..bb7621d 100644
--- a/logd/LogStatistics.cpp
+++ b/logd/LogStatistics.cpp
@@ -79,12 +79,9 @@
 }
 }
 
-void LogStatistics::AddTotal(LogBufferElement* element) {
+void LogStatistics::AddTotal(log_id_t log_id, uint16_t size) {
     auto lock = std::lock_guard{lock_};
-    if (element->getDropped()) return;
 
-    log_id_t log_id = element->getLogId();
-    uint16_t size = element->getMsgLen();
     mSizesTotal[log_id] += size;
     SizesTotal += size;
     ++mElementsTotal[log_id];
diff --git a/logd/LogStatistics.h b/logd/LogStatistics.h
index 53c9bb6..7d13ff7 100644
--- a/logd/LogStatistics.h
+++ b/logd/LogStatistics.h
@@ -666,7 +666,7 @@
   public:
     LogStatistics(bool enable_statistics);
 
-    void AddTotal(LogBufferElement* entry) EXCLUDES(lock_);
+    void AddTotal(log_id_t log_id, uint16_t size) EXCLUDES(lock_);
     void Add(LogBufferElement* entry) EXCLUDES(lock_);
     void Subtract(LogBufferElement* entry) EXCLUDES(lock_);
     // entry->setDropped(1) must follow this call
diff --git a/logd/rwlock.h b/logd/rwlock.h
new file mode 100644
index 0000000..2b27ff1
--- /dev/null
+++ b/logd/rwlock.h
@@ -0,0 +1,56 @@
+/*
+ * 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/LICENSE2.0
+ *
+ * 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 <pthread.h>
+
+#include <android-base/macros.h>
+#include <android-base/thread_annotations.h>
+
+// As of the end of May 2020, std::shared_mutex is *not* simply a pthread_rwlock, but rather a
+// combination of std::mutex and std::condition variable, which is obviously less efficient.  This
+// immitates what std::shared_mutex should be doing and is compatible with RAII thread wrappers.
+
+class SHARED_CAPABILITY("mutex") RwLock {
+  public:
+    RwLock() {}
+    ~RwLock() {}
+
+    void lock() ACQUIRE() { pthread_rwlock_wrlock(&rwlock_); }
+    void lock_shared() ACQUIRE_SHARED() { pthread_rwlock_rdlock(&rwlock_); }
+
+    void unlock() RELEASE() { pthread_rwlock_unlock(&rwlock_); }
+
+  private:
+    pthread_rwlock_t rwlock_ = PTHREAD_RWLOCK_INITIALIZER;
+};
+
+// std::shared_lock does not have thread annotations, so we need our own.
+
+class SCOPED_CAPABILITY SharedLock {
+  public:
+    SharedLock(RwLock& lock) ACQUIRE_SHARED(lock) : lock_(lock) { lock_.lock_shared(); }
+    ~SharedLock() RELEASE() { lock_.unlock(); }
+
+    void lock_shared() ACQUIRE_SHARED() { lock_.lock_shared(); }
+    void unlock() RELEASE() { lock_.unlock(); }
+
+    DISALLOW_IMPLICIT_CONSTRUCTORS(SharedLock);
+
+  private:
+    RwLock& lock_;
+};