diff --git a/adb/adb.cpp b/adb/adb.cpp
index 90ee7b4..65fa2e7 100644
--- a/adb/adb.cpp
+++ b/adb/adb.cpp
@@ -136,8 +136,16 @@
 
 void handle_offline(atransport *t)
 {
-    D("adb: offline");
-    //Close the associated usb
+    if (t->GetConnectionState() == kCsOffline) {
+        LOG(INFO) << t->serial_name() << ": already offline";
+        return;
+    }
+
+    LOG(INFO) << t->serial_name() << ": offline";
+
+    t->SetConnectionState(kCsOffline);
+
+    // Close the associated usb
     t->online = 0;
 
     // This is necessary to avoid a race condition that occurred when a transport closes
@@ -318,10 +326,7 @@
 }
 
 static void handle_new_connection(atransport* t, apacket* p) {
-    if (t->GetConnectionState() != kCsOffline) {
-        t->SetConnectionState(kCsOffline);
-        handle_offline(t);
-    }
+    handle_offline(t);
 
     t->update_version(p->msg.arg0, p->msg.arg1);
     parse_banner(p->payload, t);
@@ -350,19 +355,6 @@
     CHECK_EQ(p->payload.size(), p->msg.data_length);
 
     switch(p->msg.command){
-    case A_SYNC:
-        if (p->msg.arg0){
-            send_packet(p, t);
-#if ADB_HOST
-            send_connect(t);
-#endif
-        } else {
-            t->SetConnectionState(kCsOffline);
-            handle_offline(t);
-            send_packet(p, t);
-        }
-        return;
-
     case A_CNXN:  // CONNECT(version, maxdata, "system-id-string")
         handle_new_connection(t, p);
         break;
diff --git a/adb/protocol.txt b/adb/protocol.txt
index 55ea87f..f4523c4 100644
--- a/adb/protocol.txt
+++ b/adb/protocol.txt
@@ -183,9 +183,11 @@
 
 Command constant: A_SYNC
 
-The SYNC message is used by the io pump to make sure that stale
+*** obsolete, no longer used ***
+
+The SYNC message was used by the io pump to make sure that stale
 outbound messages are discarded when the connection to the remote side
-is broken.  It is only used internally to the bridge and never valid
+is broken.  It was only used internally to the bridge and never valid
 to send across the wire.
 
 * when the connection to the remote side goes offline, the io pump
diff --git a/adb/transport.cpp b/adb/transport.cpp
index e7a94d5..1ccff92 100644
--- a/adb/transport.cpp
+++ b/adb/transport.cpp
@@ -28,6 +28,7 @@
 #include <unistd.h>
 
 #include <algorithm>
+#include <deque>
 #include <list>
 #include <mutex>
 #include <thread>
@@ -66,6 +67,82 @@
     return next++;
 }
 
+BlockingConnectionAdapter::BlockingConnectionAdapter(std::unique_ptr<BlockingConnection> connection)
+    : underlying_(std::move(connection)) {}
+
+BlockingConnectionAdapter::~BlockingConnectionAdapter() {
+    LOG(INFO) << "BlockingConnectionAdapter(" << this->transport_name_ << "): destructing";
+    Stop();
+}
+
+void BlockingConnectionAdapter::Start() {
+    read_thread_ = std::thread([this]() {
+        LOG(INFO) << this->transport_name_ << ": read thread spawning";
+        while (true) {
+            std::unique_ptr<apacket> packet(new apacket());
+            if (!underlying_->Read(packet.get())) {
+                PLOG(INFO) << this->transport_name_ << ": read failed";
+                break;
+            }
+            read_callback_(this, std::move(packet));
+        }
+        std::call_once(this->error_flag_, [this]() { this->error_callback_(this, "read failed"); });
+    });
+
+    write_thread_ = std::thread([this]() {
+        LOG(INFO) << this->transport_name_ << ": write thread spawning";
+        while (true) {
+            std::unique_lock<std::mutex> lock(mutex_);
+            cv_.wait(lock, [this]() { return this->stopped_ || !this->write_queue_.empty(); });
+
+            if (this->stopped_) {
+                return;
+            }
+
+            std::unique_ptr<apacket> packet = std::move(this->write_queue_.front());
+            this->write_queue_.pop_front();
+            lock.unlock();
+
+            if (!this->underlying_->Write(packet.get())) {
+                break;
+            }
+        }
+        std::call_once(this->error_flag_, [this]() { this->error_callback_(this, "write failed"); });
+    });
+}
+
+void BlockingConnectionAdapter::Stop() {
+    std::unique_lock<std::mutex> lock(mutex_);
+    if (stopped_) {
+        LOG(INFO) << "BlockingConnectionAdapter(" << this->transport_name_ << "): already stopped";
+        return;
+    }
+
+    stopped_ = true;
+    lock.unlock();
+
+    LOG(INFO) << "BlockingConnectionAdapter(" << this->transport_name_ << "): stopping";
+
+    this->underlying_->Close();
+
+    this->cv_.notify_one();
+    read_thread_.join();
+    write_thread_.join();
+
+    LOG(INFO) << "BlockingConnectionAdapter(" << this->transport_name_ << "): stopped";
+    std::call_once(this->error_flag_, [this]() { this->error_callback_(this, "requested stop"); });
+}
+
+bool BlockingConnectionAdapter::Write(std::unique_ptr<apacket> packet) {
+    {
+        std::unique_lock<std::mutex> lock(this->mutex_);
+        write_queue_.emplace_back(std::move(packet));
+    }
+
+    cv_.notify_one();
+    return true;
+}
+
 bool FdConnection::Read(apacket* packet) {
     if (!ReadFdExactly(fd_.get(), &packet->msg, sizeof(amessage))) {
         D("remote local: read terminated (message)");
@@ -144,67 +221,6 @@
     return result;
 }
 
-static int read_packet(int fd, const char* name, apacket** ppacket) {
-    ATRACE_NAME("read_packet");
-    char buff[8];
-    if (!name) {
-        snprintf(buff, sizeof buff, "fd=%d", fd);
-        name = buff;
-    }
-    char* p = reinterpret_cast<char*>(ppacket); /* really read a packet address */
-    int len = sizeof(apacket*);
-    while (len > 0) {
-        int r = adb_read(fd, p, len);
-        if (r > 0) {
-            len -= r;
-            p += r;
-        } else {
-            D("%s: read_packet (fd=%d), error ret=%d: %s", name, fd, r, strerror(errno));
-            return -1;
-        }
-    }
-
-    VLOG(TRANSPORT) << dump_packet(name, "from remote", *ppacket);
-    return 0;
-}
-
-static int write_packet(int fd, const char* name, apacket** ppacket) {
-    ATRACE_NAME("write_packet");
-    char buff[8];
-    if (!name) {
-        snprintf(buff, sizeof buff, "fd=%d", fd);
-        name = buff;
-    }
-    VLOG(TRANSPORT) << dump_packet(name, "to remote", *ppacket);
-    char* p = reinterpret_cast<char*>(ppacket); /* we really write the packet address */
-    int len = sizeof(apacket*);
-    while (len > 0) {
-        int r = adb_write(fd, p, len);
-        if (r > 0) {
-            len -= r;
-            p += r;
-        } else {
-            D("%s: write_packet (fd=%d) error ret=%d: %s", name, fd, r, strerror(errno));
-            return -1;
-        }
-    }
-    return 0;
-}
-
-static void transport_socket_events(int fd, unsigned events, void* _t) {
-    atransport* t = reinterpret_cast<atransport*>(_t);
-    D("transport_socket_events(fd=%d, events=%04x,...)", fd, events);
-    if (events & FDE_READ) {
-        apacket* p = 0;
-        if (read_packet(fd, t->serial, &p)) {
-            D("%s: failed to read packet from transport socket on fd %d", t->serial, fd);
-            return;
-        }
-
-        handle_packet(p, (atransport*)_t);
-    }
-}
-
 void send_packet(apacket* p, atransport* t) {
     p->msg.magic = p->msg.command ^ 0xffffffff;
     // compute a checksum for connection/auth packets for compatibility reasons
@@ -214,162 +230,18 @@
         p->msg.data_check = calculate_apacket_checksum(p);
     }
 
-    print_packet("send", p);
+    VLOG(TRANSPORT) << dump_packet(t->serial, "to remote", p);
 
     if (t == NULL) {
         fatal("Transport is null");
     }
 
-    if (write_packet(t->transport_socket, t->serial, &p)) {
-        fatal_errno("cannot enqueue packet on transport socket");
+    if (t->Write(p) != 0) {
+        D("%s: failed to enqueue packet, closing transport", t->serial);
+        t->Kick();
     }
 }
 
-// The transport is opened by transport_register_func before
-// the read_transport and write_transport threads are started.
-//
-// The read_transport thread issues a SYNC(1, token) message to let
-// the write_transport thread know to start things up.  In the event
-// of transport IO failure, the read_transport thread will post a
-// SYNC(0,0) message to ensure shutdown.
-//
-// The transport will not actually be closed until both threads exit, but the threads
-// will kick the transport on their way out to disconnect the underlying device.
-//
-// read_transport thread reads data from a transport (representing a usb/tcp connection),
-// and makes the main thread call handle_packet().
-static void read_transport_thread(void* _t) {
-    atransport* t = reinterpret_cast<atransport*>(_t);
-    apacket* p;
-
-    adb_thread_setname(
-        android::base::StringPrintf("<-%s", (t->serial != nullptr ? t->serial : "transport")));
-    D("%s: starting read_transport thread on fd %d, SYNC online (%d)", t->serial, t->fd,
-      t->sync_token + 1);
-    p = get_apacket();
-    p->msg.command = A_SYNC;
-    p->msg.arg0 = 1;
-    p->msg.arg1 = ++(t->sync_token);
-    p->msg.magic = A_SYNC ^ 0xffffffff;
-    D("sending SYNC packet (len = %u, payload.size() = %zu)", p->msg.data_length, p->payload.size());
-    if (write_packet(t->fd, t->serial, &p)) {
-        put_apacket(p);
-        D("%s: failed to write SYNC packet", t->serial);
-        goto oops;
-    }
-
-    D("%s: data pump started", t->serial);
-    for (;;) {
-        ATRACE_NAME("read_transport loop");
-        p = get_apacket();
-
-        {
-            ATRACE_NAME("read_transport read_remote");
-            if (!t->connection->Read(p)) {
-                D("%s: remote read failed for transport", t->serial);
-                put_apacket(p);
-                break;
-            }
-
-            if (!check_header(p, t)) {
-                D("%s: remote read: bad header", t->serial);
-                put_apacket(p);
-                break;
-            }
-
-#if ADB_HOST
-            if (p->msg.command == 0) {
-                put_apacket(p);
-                continue;
-            }
-#endif
-        }
-
-        D("%s: received remote packet, sending to transport", t->serial);
-        if (write_packet(t->fd, t->serial, &p)) {
-            put_apacket(p);
-            D("%s: failed to write apacket to transport", t->serial);
-            goto oops;
-        }
-    }
-
-    D("%s: SYNC offline for transport", t->serial);
-    p = get_apacket();
-    p->msg.command = A_SYNC;
-    p->msg.arg0 = 0;
-    p->msg.arg1 = 0;
-    p->msg.magic = A_SYNC ^ 0xffffffff;
-    if (write_packet(t->fd, t->serial, &p)) {
-        put_apacket(p);
-        D("%s: failed to write SYNC apacket to transport", t->serial);
-    }
-
-oops:
-    D("%s: read_transport thread is exiting", t->serial);
-    kick_transport(t);
-    transport_unref(t);
-}
-
-// write_transport thread gets packets sent by the main thread (through send_packet()),
-// and writes to a transport (representing a usb/tcp connection).
-static void write_transport_thread(void* _t) {
-    atransport* t = reinterpret_cast<atransport*>(_t);
-    apacket* p;
-    int active = 0;
-
-    adb_thread_setname(
-        android::base::StringPrintf("->%s", (t->serial != nullptr ? t->serial : "transport")));
-    D("%s: starting write_transport thread, reading from fd %d", t->serial, t->fd);
-
-    for (;;) {
-        ATRACE_NAME("write_transport loop");
-        if (read_packet(t->fd, t->serial, &p)) {
-            D("%s: failed to read apacket from transport on fd %d", t->serial, t->fd);
-            break;
-        }
-
-        if (p->msg.command == A_SYNC) {
-            if (p->msg.arg0 == 0) {
-                D("%s: transport SYNC offline", t->serial);
-                put_apacket(p);
-                break;
-            } else {
-                if (p->msg.arg1 == t->sync_token) {
-                    D("%s: transport SYNC online", t->serial);
-                    active = 1;
-                } else {
-                    D("%s: transport ignoring SYNC %d != %d", t->serial, p->msg.arg1, t->sync_token);
-                }
-            }
-        } else {
-            if (active) {
-                D("%s: transport got packet, sending to remote", t->serial);
-                ATRACE_NAME("write_transport write_remote");
-
-                // Allow sending the payload's implicit null terminator.
-                if (p->msg.data_length != p->payload.size()) {
-                    LOG(FATAL) << "packet data length doesn't match payload: msg.data_length = "
-                               << p->msg.data_length << ", payload.size() = " << p->payload.size();
-                }
-
-                if (t->Write(p) != 0) {
-                    D("%s: remote write failed for transport", t->serial);
-                    put_apacket(p);
-                    break;
-                }
-            } else {
-                D("%s: transport ignoring packet while offline", t->serial);
-            }
-        }
-
-        put_apacket(p);
-    }
-
-    D("%s: write_transport thread is exiting, fd %d", t->serial, t->fd);
-    kick_transport(t);
-    transport_unref(t);
-}
-
 void kick_transport(atransport* t) {
     std::lock_guard<std::recursive_mutex> lock(transport_lock);
     // As kick_transport() can be called from threads without guarantee that t is valid,
@@ -560,9 +432,10 @@
     return 0;
 }
 
-static void transport_registration_func(int _fd, unsigned ev, void* data) {
+static void remove_transport(atransport*);
+
+static void transport_registration_func(int _fd, unsigned ev, void*) {
     tmsg m;
-    int s[2];
     atransport* t;
 
     if (!(ev & FDE_READ)) {
@@ -576,13 +449,7 @@
     t = m.transport;
 
     if (m.action == 0) {
-        D("transport: %s removing and free'ing %d", t->serial, t->transport_socket);
-
-        /* IMPORTANT: the remove closes one half of the
-        ** socket pair.  The close closes the other half.
-        */
-        fdevent_remove(&(t->transport_fde));
-        adb_close(t->fd);
+        D("transport: %s deleting", t->serial);
 
         {
             std::lock_guard<std::recursive_mutex> lock(transport_lock);
@@ -604,23 +471,33 @@
     /* don't create transport threads for inaccessible devices */
     if (t->GetConnectionState() != kCsNoPerm) {
         /* initial references are the two threads */
-        t->ref_count = 2;
+        t->ref_count = 1;
+        t->connection->SetTransportName(t->serial_name());
+        t->connection->SetReadCallback([t](Connection*, std::unique_ptr<apacket> p) {
+            if (!check_header(p.get(), t)) {
+                D("%s: remote read: bad header", t->serial);
+                return false;
+            }
 
-        if (adb_socketpair(s)) {
-            fatal_errno("cannot open transport socketpair");
-        }
+            VLOG(TRANSPORT) << dump_packet(t->serial, "from remote", p.get());
+            apacket* packet = p.release();
 
-        D("transport: %s socketpair: (%d,%d) starting", t->serial, s[0], s[1]);
+            // TODO: Does this need to run on the main thread?
+            fdevent_run_on_main_thread([packet, t]() { handle_packet(packet, t); });
+            return true;
+        });
+        t->connection->SetErrorCallback([t](Connection*, const std::string& error) {
+            D("%s: connection terminated: %s", t->serial, error.c_str());
+            fdevent_run_on_main_thread([t]() {
+                handle_offline(t);
+                transport_unref(t);
+            });
+        });
 
-        t->transport_socket = s[0];
-        t->fd = s[1];
-
-        fdevent_install(&(t->transport_fde), t->transport_socket, transport_socket_events, t);
-
-        fdevent_set(&(t->transport_fde), FDE_READ);
-
-        std::thread(write_transport_thread, t).detach();
-        std::thread(read_transport_thread, t).detach();
+        t->connection->Start();
+#if ADB_HOST
+        send_connect(t);
+#endif
     }
 
     {
@@ -686,7 +563,7 @@
     t->ref_count--;
     if (t->ref_count == 0) {
         D("transport: %s unref (kicking and closing)", t->serial);
-        t->connection->Close();
+        t->connection->Stop();
         remove_transport(t);
     } else {
         D("transport: %s unref (count=%zu)", t->serial, t->ref_count);
@@ -812,14 +689,14 @@
 }
 
 int atransport::Write(apacket* p) {
-    return this->connection->Write(p) ? 0 : -1;
+    return this->connection->Write(std::unique_ptr<apacket>(p)) ? 0 : -1;
 }
 
 void atransport::Kick() {
     if (!kicked_) {
         D("kicking transport %s", this->serial);
         kicked_ = true;
-        this->connection->Close();
+        this->connection->Stop();
     }
 }
 
diff --git a/adb/transport.h b/adb/transport.h
index 9700f44..a492f00 100644
--- a/adb/transport.h
+++ b/adb/transport.h
@@ -20,12 +20,14 @@
 #include <sys/types.h>
 
 #include <atomic>
+#include <condition_variable>
 #include <deque>
 #include <functional>
 #include <list>
 #include <memory>
 #include <mutex>
 #include <string>
+#include <thread>
 #include <unordered_set>
 
 #include <openssl/rsa.h>
@@ -57,15 +59,47 @@
 
 TransportId NextTransportId();
 
-// Abstraction for a blocking packet transport.
+// Abstraction for a non-blocking packet transport.
 struct Connection {
     Connection() = default;
-    Connection(const Connection& copy) = delete;
-    Connection(Connection&& move) = delete;
-
-    // Destroy a Connection. Formerly known as 'Close' in atransport.
     virtual ~Connection() = default;
 
+    void SetTransportName(std::string transport_name) {
+        transport_name_ = std::move(transport_name);
+    }
+
+    using ReadCallback = std::function<bool(Connection*, std::unique_ptr<apacket>)>;
+    void SetReadCallback(ReadCallback callback) {
+        CHECK(!read_callback_);
+        read_callback_ = callback;
+    }
+
+    // Called after the Connection has terminated, either by an error or because Stop was called.
+    using ErrorCallback = std::function<void(Connection*, const std::string&)>;
+    void SetErrorCallback(ErrorCallback callback) {
+        CHECK(!error_callback_);
+        error_callback_ = callback;
+    }
+
+    virtual bool Write(std::unique_ptr<apacket> packet) = 0;
+
+    virtual void Start() = 0;
+    virtual void Stop() = 0;
+
+    std::string transport_name_;
+    ReadCallback read_callback_;
+    ErrorCallback error_callback_;
+};
+
+// Abstraction for a blocking packet transport.
+struct BlockingConnection {
+    BlockingConnection() = default;
+    BlockingConnection(const BlockingConnection& copy) = delete;
+    BlockingConnection(BlockingConnection&& move) = delete;
+
+    // Destroy a BlockingConnection. Formerly known as 'Close' in atransport.
+    virtual ~BlockingConnection() = default;
+
     // Read/Write a packet. These functions are concurrently called from a transport's reader/writer
     // threads.
     virtual bool Read(apacket* packet) = 0;
@@ -77,7 +111,30 @@
     virtual void Close() = 0;
 };
 
-struct FdConnection : public Connection {
+struct BlockingConnectionAdapter : public Connection {
+    explicit BlockingConnectionAdapter(std::unique_ptr<BlockingConnection> connection);
+
+    virtual ~BlockingConnectionAdapter();
+
+    virtual bool Write(std::unique_ptr<apacket> packet) override final;
+
+    virtual void Start() override final;
+    virtual void Stop() override final;
+
+    bool stopped_ = false;
+
+    std::unique_ptr<BlockingConnection> underlying_;
+    std::thread read_thread_;
+    std::thread write_thread_;
+
+    std::deque<std::unique_ptr<apacket>> write_queue_;
+    std::mutex mutex_;
+    std::condition_variable cv_;
+
+    std::once_flag error_flag_;
+};
+
+struct FdConnection : public BlockingConnection {
     explicit FdConnection(unique_fd fd) : fd_(std::move(fd)) {}
 
     bool Read(apacket* packet) override final;
@@ -89,7 +146,7 @@
     unique_fd fd_;
 };
 
-struct UsbConnection : public Connection {
+struct UsbConnection : public BlockingConnection {
     explicit UsbConnection(usb_handle* handle) : handle_(handle) {}
     ~UsbConnection();
 
@@ -110,7 +167,6 @@
 
     atransport(ConnectionState state = kCsOffline)
         : id(NextTransportId()), connection_state_(state) {
-        transport_fde = {};
         // Initialize protocol to min version for compatibility with older versions.
         // Version will be updated post-connect.
         protocol_version = A_VERSION_MIN;
@@ -126,11 +182,7 @@
     void SetConnectionState(ConnectionState state);
 
     const TransportId id;
-    int fd = -1;
-    int transport_socket = -1;
-    fdevent transport_fde;
     size_t ref_count = 0;
-    uint32_t sync_token = 0;
     bool online = false;
     TransportType type = kTransportAny;
 
diff --git a/adb/transport_local.cpp b/adb/transport_local.cpp
index 560a031..ff395dc 100644
--- a/adb/transport_local.cpp
+++ b/adb/transport_local.cpp
@@ -445,13 +445,14 @@
     int fail = 0;
 
     unique_fd fd(s);
-    t->sync_token = 1;
     t->type = kTransportLocal;
 
 #if ADB_HOST
     // Emulator connection.
     if (local) {
-        t->connection.reset(new EmulatorConnection(std::move(fd), adb_port));
+        std::unique_ptr<BlockingConnection> emulator_connection(
+            new EmulatorConnection(std::move(fd), adb_port));
+        t->connection.reset(new BlockingConnectionAdapter(std::move(emulator_connection)));
         std::lock_guard<std::mutex> lock(local_transports_lock);
         atransport* existing_transport = find_emulator_transport_by_adb_port_locked(adb_port);
         if (existing_transport != NULL) {
@@ -470,6 +471,7 @@
 #endif
 
     // Regular tcp connection.
-    t->connection.reset(new FdConnection(std::move(fd)));
+    std::unique_ptr<BlockingConnection> fd_connection(new FdConnection(std::move(fd)));
+    t->connection.reset(new BlockingConnectionAdapter(std::move(fd_connection)));
     return fail;
 }
diff --git a/adb/transport_usb.cpp b/adb/transport_usb.cpp
index d7565f6..33e00a1 100644
--- a/adb/transport_usb.cpp
+++ b/adb/transport_usb.cpp
@@ -174,8 +174,8 @@
 
 void init_usb_transport(atransport* t, usb_handle* h) {
     D("transport: usb");
-    t->connection.reset(new UsbConnection(h));
-    t->sync_token = 1;
+    std::unique_ptr<BlockingConnection> connection(new UsbConnection(h));
+    t->connection.reset(new BlockingConnectionAdapter(std::move(connection)));
     t->type = kTransportUsb;
 }