Merge "Implement sysprop_library API stability check" into stage-aosp-master
diff --git a/adb/Android.bp b/adb/Android.bp
index 06cfcbf..57872b0 100644
--- a/adb/Android.bp
+++ b/adb/Android.bp
@@ -142,6 +142,10 @@
     "sysdeps/posix/network.cpp",
 ]
 
+libadb_linux_srcs = [
+    "fdevent/fdevent_epoll.cpp",
+]
+
 libadb_test_srcs = [
     "adb_io_test.cpp",
     "adb_listeners_test.cpp",
@@ -170,12 +174,11 @@
 
     target: {
         linux: {
-            srcs: ["client/usb_linux.cpp"],
+            srcs: ["client/usb_linux.cpp"] + libadb_linux_srcs,
         },
         darwin: {
             srcs: ["client/usb_osx.cpp"],
         },
-
         not_windows: {
             srcs: libadb_posix_srcs,
         },
@@ -342,7 +345,7 @@
     // libminadbd wants both, as it's used to build native tests.
     compile_multilib: "both",
 
-    srcs: libadb_srcs + libadb_posix_srcs + [
+    srcs: libadb_srcs + libadb_linux_srcs + libadb_posix_srcs + [
         "daemon/auth.cpp",
         "daemon/jdwp_service.cpp",
     ],
diff --git a/adb/fdevent/fdevent.cpp b/adb/fdevent/fdevent.cpp
index 28b8f37..562f587 100644
--- a/adb/fdevent/fdevent.cpp
+++ b/adb/fdevent/fdevent.cpp
@@ -26,16 +26,24 @@
 
 #include "adb_utils.h"
 #include "fdevent.h"
+#include "fdevent_epoll.h"
 #include "fdevent_poll.h"
 
+using namespace std::chrono_literals;
+using std::chrono::duration_cast;
+
+void invoke_fde(struct fdevent* fde, unsigned events) {
+    if (auto f = std::get_if<fd_func>(&fde->func)) {
+        (*f)(fde->fd.get(), events, fde->arg);
+    } else if (auto f = std::get_if<fd_func2>(&fde->func)) {
+        (*f)(fde, events, fde->arg);
+    } else {
+        __builtin_unreachable();
+    }
+}
+
 std::string dump_fde(const fdevent* fde) {
     std::string state;
-    if (fde->state & FDE_ACTIVE) {
-        state += "A";
-    }
-    if (fde->state & FDE_PENDING) {
-        state += "P";
-    }
     if (fde->state & FDE_READ) {
         state += "R";
     }
@@ -53,9 +61,11 @@
     CheckMainThread();
     CHECK_GE(fd.get(), 0);
 
+    int fd_num = fd.get();
+
     fdevent* fde = new fdevent();
     fde->id = fdevent_id_++;
-    fde->state = FDE_ACTIVE;
+    fde->state = 0;
     fde->fd = std::move(fd);
     fde->func = func;
     fde->arg = arg;
@@ -66,6 +76,10 @@
         LOG(ERROR) << "failed to set non-blocking mode for fd " << fde->fd.get();
     }
 
+    auto [it, inserted] = this->installed_fdevents_.emplace(fd_num, fde);
+    CHECK(inserted);
+    UNUSED(it);
+
     this->Register(fde);
     return fde;
 }
@@ -78,18 +92,22 @@
 
     this->Unregister(fde);
 
+    auto erased = this->installed_fdevents_.erase(fde->fd.get());
+    CHECK_EQ(1UL, erased);
+
     unique_fd result = std::move(fde->fd);
     delete fde;
     return result;
 }
 
 void fdevent_context::Add(fdevent* fde, unsigned events) {
-    Set(fde, (fde->state & FDE_EVENTMASK) | events);
+    CHECK(!(events & FDE_TIMEOUT));
+    Set(fde, fde->state | events);
 }
 
 void fdevent_context::Del(fdevent* fde, unsigned events) {
     CHECK(!(events & FDE_TIMEOUT));
-    Set(fde, (fde->state & FDE_EVENTMASK) & ~events);
+    Set(fde, fde->state & ~events);
 }
 
 void fdevent_context::SetTimeout(fdevent* fde, std::optional<std::chrono::milliseconds> timeout) {
@@ -98,6 +116,56 @@
     fde->last_active = std::chrono::steady_clock::now();
 }
 
+std::optional<std::chrono::milliseconds> fdevent_context::CalculatePollDuration() {
+    std::optional<std::chrono::milliseconds> result = std::nullopt;
+    auto now = std::chrono::steady_clock::now();
+    CheckMainThread();
+
+    for (const auto& [fd, fde] : this->installed_fdevents_) {
+        UNUSED(fd);
+        auto timeout_opt = fde->timeout;
+        if (timeout_opt) {
+            auto deadline = fde->last_active + *timeout_opt;
+            auto time_left = duration_cast<std::chrono::milliseconds>(deadline - now);
+            if (time_left < 0ms) {
+                time_left = 0ms;
+            }
+
+            if (!result) {
+                result = time_left;
+            } else {
+                result = std::min(*result, time_left);
+            }
+        }
+    }
+
+    return result;
+}
+
+void fdevent_context::HandleEvents(const std::vector<fdevent_event>& events) {
+    for (const auto& event : events) {
+        invoke_fde(event.fde, event.events);
+    }
+    FlushRunQueue();
+}
+
+void fdevent_context::FlushRunQueue() {
+    // We need to be careful around reentrancy here, since a function we call can queue up another
+    // function.
+    while (true) {
+        std::function<void()> fn;
+        {
+            std::lock_guard<std::mutex> lock(this->run_queue_mutex_);
+            if (this->run_queue_.empty()) {
+                break;
+            }
+            fn = std::move(this->run_queue_.front());
+            this->run_queue_.pop_front();
+        }
+        fn();
+    }
+}
+
 void fdevent_context::CheckMainThread() {
     if (main_thread_id_) {
         CHECK_EQ(*main_thread_id_, android::base::GetThreadId());
@@ -118,25 +186,16 @@
     Interrupt();
 }
 
-void fdevent_context::FlushRunQueue() {
-    // We need to be careful around reentrancy here, since a function we call can queue up another
-    // function.
-    while (true) {
-        std::function<void()> fn;
-        {
-            std::lock_guard<std::mutex> lock(this->run_queue_mutex_);
-            if (this->run_queue_.empty()) {
-                break;
-            }
-            fn = this->run_queue_.front();
-            this->run_queue_.pop_front();
-        }
-        fn();
-    }
+static std::unique_ptr<fdevent_context> fdevent_create_context() {
+#if defined(__linux__)
+    return std::make_unique<fdevent_context_epoll>();
+#else
+    return std::make_unique<fdevent_context_poll>();
+#endif
 }
 
 static auto& g_ambient_fdevent_context =
-        *new std::unique_ptr<fdevent_context>(new fdevent_context_poll());
+        *new std::unique_ptr<fdevent_context>(fdevent_create_context());
 
 static fdevent_context* fdevent_get_ambient() {
     return g_ambient_fdevent_context.get();
@@ -197,5 +256,5 @@
 }
 
 void fdevent_reset() {
-    g_ambient_fdevent_context.reset(new fdevent_context_poll());
+    g_ambient_fdevent_context = fdevent_create_context();
 }
diff --git a/adb/fdevent/fdevent.h b/adb/fdevent/fdevent.h
index 2424252..86814d7 100644
--- a/adb/fdevent/fdevent.h
+++ b/adb/fdevent/fdevent.h
@@ -26,6 +26,7 @@
 #include <functional>
 #include <mutex>
 #include <optional>
+#include <unordered_map>
 #include <variant>
 
 #include <android-base/thread_annotations.h>
@@ -38,19 +39,19 @@
 #define FDE_ERROR 0x0004
 #define FDE_TIMEOUT 0x0008
 
-// Internal states.
-#define FDE_EVENTMASK  0x00ff
-#define FDE_STATEMASK  0xff00
-
-#define FDE_ACTIVE     0x0100
-#define FDE_PENDING    0x0200
+struct fdevent;
 
 typedef void (*fd_func)(int fd, unsigned events, void *userdata);
 typedef void (*fd_func2)(struct fdevent* fde, unsigned events, void* userdata);
 
-struct fdevent;
+void invoke_fde(struct fdevent* fde, unsigned events);
 std::string dump_fde(const fdevent* fde);
 
+struct fdevent_event {
+    fdevent* fde;
+    unsigned events;
+};
+
 struct fdevent_context {
   public:
     virtual ~fdevent_context() = default;
@@ -59,14 +60,13 @@
     fdevent* Create(unique_fd fd, std::variant<fd_func, fd_func2> func, void* arg);
 
     // Deallocate an fdevent object, returning the file descriptor that was owned by it.
+    // Note that this calls Set, which is a virtual method, so destructors that call this must be
+    // final.
     unique_fd Destroy(fdevent* fde);
 
   protected:
-    // Register an fdevent that is being created by Create with the fdevent_context.
-    virtual void Register(fdevent* fde) = 0;
-
-    // Unregister an fdevent that is being destroyed by Destroy with the fdevent_context.
-    virtual void Unregister(fdevent* fde) = 0;
+    virtual void Register(fdevent*) {}
+    virtual void Unregister(fdevent*) {}
 
   public:
     // Change which events should cause notifications.
@@ -80,6 +80,15 @@
     // trigger repeatedly every |timeout| ms.
     void SetTimeout(fdevent* fde, std::optional<std::chrono::milliseconds> timeout);
 
+  protected:
+    std::optional<std::chrono::milliseconds> CalculatePollDuration();
+    void HandleEvents(const std::vector<fdevent_event>& events);
+
+  private:
+    // Run all pending functions enqueued via Run().
+    void FlushRunQueue() EXCLUDES(run_queue_mutex_);
+
+  public:
     // Loop until TerminateLoop is called, handling events.
     // Implementations should call FlushRunQueue on every iteration, and check the value of
     // terminate_loop_ to determine whether to stop.
@@ -100,12 +109,12 @@
     // Interrupt the run loop.
     virtual void Interrupt() = 0;
 
-    // Run all pending functions enqueued via Run().
-    void FlushRunQueue() EXCLUDES(run_queue_mutex_);
-
     std::optional<uint64_t> main_thread_id_ = std::nullopt;
     std::atomic<bool> terminate_loop_ = false;
 
+  protected:
+    std::unordered_map<int, fdevent*> installed_fdevents_;
+
   private:
     uint64_t fdevent_id_ = 0;
     std::mutex run_queue_mutex_;
@@ -119,7 +128,6 @@
     int force_eof = 0;
 
     uint16_t state = 0;
-    uint16_t events = 0;
     std::optional<std::chrono::milliseconds> timeout;
     std::chrono::steady_clock::time_point last_active;
 
diff --git a/adb/fdevent/fdevent_epoll.cpp b/adb/fdevent/fdevent_epoll.cpp
new file mode 100644
index 0000000..e3d1674
--- /dev/null
+++ b/adb/fdevent/fdevent_epoll.cpp
@@ -0,0 +1,200 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "fdevent_epoll.h"
+
+#if defined(__linux__)
+
+#include <sys/epoll.h>
+#include <sys/eventfd.h>
+
+#include <android-base/logging.h>
+#include <android-base/threads.h>
+
+#include "adb_unique_fd.h"
+#include "fdevent.h"
+
+static void fdevent_interrupt(int fd, unsigned, void*) {
+    uint64_t buf;
+    ssize_t rc = TEMP_FAILURE_RETRY(adb_read(fd, &buf, sizeof(buf)));
+    if (rc == -1) {
+        PLOG(FATAL) << "failed to read from fdevent interrupt fd";
+    }
+}
+
+fdevent_context_epoll::fdevent_context_epoll() {
+    epoll_fd_.reset(epoll_create1(EPOLL_CLOEXEC));
+
+    unique_fd interrupt_fd(eventfd(0, EFD_CLOEXEC | EFD_NONBLOCK));
+    if (interrupt_fd == -1) {
+        PLOG(FATAL) << "failed to create fdevent interrupt eventfd";
+    }
+
+    unique_fd interrupt_fd_dup(fcntl(interrupt_fd.get(), F_DUPFD_CLOEXEC, 3));
+    if (interrupt_fd_dup == -1) {
+        PLOG(FATAL) << "failed to dup fdevent interrupt eventfd";
+    }
+
+    this->interrupt_fd_ = std::move(interrupt_fd_dup);
+    fdevent* fde = this->Create(std::move(interrupt_fd), fdevent_interrupt, nullptr);
+    CHECK(fde != nullptr);
+    this->Add(fde, FDE_READ);
+}
+
+fdevent_context_epoll::~fdevent_context_epoll() {
+    // Destroy calls virtual methods, but this class is final, so that's okay.
+    this->Destroy(this->interrupt_fde_);
+}
+
+static epoll_event calculate_epoll_event(fdevent* fde) {
+    epoll_event result;
+    result.events = 0;
+    if (fde->state & FDE_READ) {
+        result.events |= EPOLLIN;
+    }
+    if (fde->state & FDE_WRITE) {
+        result.events |= EPOLLOUT;
+    }
+    if (fde->state & FDE_ERROR) {
+        result.events |= EPOLLERR;
+    }
+    result.events |= EPOLLRDHUP;
+    result.data.ptr = fde;
+    return result;
+}
+
+void fdevent_context_epoll::Register(fdevent* fde) {
+    epoll_event ev = calculate_epoll_event(fde);
+    if (epoll_ctl(epoll_fd_.get(), EPOLL_CTL_ADD, fde->fd.get(), &ev) != 0) {
+        PLOG(FATAL) << "failed to register fd " << fde->fd.get() << " with epoll";
+    }
+}
+
+void fdevent_context_epoll::Unregister(fdevent* fde) {
+    if (epoll_ctl(epoll_fd_.get(), EPOLL_CTL_DEL, fde->fd.get(), nullptr) != 0) {
+        PLOG(FATAL) << "failed to unregister fd " << fde->fd.get() << " with epoll";
+    }
+}
+
+void fdevent_context_epoll::Set(fdevent* fde, unsigned events) {
+    unsigned previous_state = fde->state;
+    fde->state = events;
+
+    // If the state is the same, or only differed by FDE_TIMEOUT, we don't need to modify epoll.
+    if ((previous_state & ~FDE_TIMEOUT) == (events & ~FDE_TIMEOUT)) {
+        return;
+    }
+
+    epoll_event ev = calculate_epoll_event(fde);
+    if (epoll_ctl(epoll_fd_.get(), EPOLL_CTL_MOD, fde->fd.get(), &ev) != 0) {
+        PLOG(FATAL) << "failed to modify fd " << fde->fd.get() << " with epoll";
+    }
+}
+
+void fdevent_context_epoll::Loop() {
+    main_thread_id_ = android::base::GetThreadId();
+
+    std::vector<fdevent_event> fde_events;
+    std::vector<epoll_event> epoll_events;
+    epoll_events.resize(this->installed_fdevents_.size());
+
+    while (true) {
+        if (terminate_loop_) {
+            break;
+        }
+
+        int rc = -1;
+        while (rc == -1) {
+            std::optional<std::chrono::milliseconds> timeout = CalculatePollDuration();
+            int timeout_ms;
+            if (!timeout) {
+                timeout_ms = -1;
+            } else {
+                timeout_ms = timeout->count();
+            }
+
+            rc = epoll_wait(epoll_fd_.get(), epoll_events.data(), epoll_events.size(), timeout_ms);
+            if (rc == -1 && errno != EINTR) {
+                PLOG(FATAL) << "epoll_wait failed";
+            }
+        }
+
+        auto post_poll = std::chrono::steady_clock::now();
+        std::unordered_map<fdevent*, unsigned> event_map;
+        for (int i = 0; i < rc; ++i) {
+            fdevent* fde = static_cast<fdevent*>(epoll_events[i].data.ptr);
+
+            unsigned events = 0;
+            if (epoll_events[i].events & EPOLLIN) {
+                CHECK(fde->state & FDE_READ);
+                events |= FDE_READ;
+            }
+            if (epoll_events[i].events & EPOLLOUT) {
+                CHECK(fde->state & FDE_WRITE);
+                events |= FDE_WRITE;
+            }
+            if (epoll_events[i].events & (EPOLLERR | EPOLLHUP | EPOLLRDHUP)) {
+                // We fake a read, as the rest of the code assumes that errors will
+                // be detected at that point.
+                events |= FDE_READ | FDE_ERROR;
+            }
+
+            event_map[fde] = events;
+        }
+
+        for (const auto& [fd, fde] : installed_fdevents_) {
+            unsigned events = 0;
+            if (auto it = event_map.find(fde); it != event_map.end()) {
+                events = it->second;
+            }
+
+            if (events == 0) {
+                if (fde->timeout) {
+                    auto deadline = fde->last_active + *fde->timeout;
+                    if (deadline < post_poll) {
+                        events |= FDE_TIMEOUT;
+                    }
+                }
+            }
+
+            if (events != 0) {
+                LOG(DEBUG) << dump_fde(fde) << " got events " << std::hex << std::showbase
+                           << events;
+                fde_events.push_back({fde, events});
+                fde->last_active = post_poll;
+            }
+        }
+        this->HandleEvents(std::move(fde_events));
+        fde_events.clear();
+    }
+
+    main_thread_id_.reset();
+}
+
+size_t fdevent_context_epoll::InstalledCount() {
+    // We always have an installed fde for interrupt.
+    return this->installed_fdevents_.size() - 1;
+}
+
+void fdevent_context_epoll::Interrupt() {
+    uint64_t i = 1;
+    ssize_t rc = TEMP_FAILURE_RETRY(adb_write(this->interrupt_fd_, &i, sizeof(i)));
+    if (rc != sizeof(i)) {
+        PLOG(FATAL) << "failed to write to fdevent interrupt eventfd";
+    }
+}
+
+#endif  // defined(__linux__)
diff --git a/adb/fdevent/fdevent_epoll.h b/adb/fdevent/fdevent_epoll.h
new file mode 100644
index 0000000..684fa32
--- /dev/null
+++ b/adb/fdevent/fdevent_epoll.h
@@ -0,0 +1,61 @@
+#pragma once
+
+/*
+ * Copyright (C) 2019 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.
+ */
+
+#if defined(__linux__)
+
+#include "sysdeps.h"
+
+#include <sys/epoll.h>
+
+#include <deque>
+#include <list>
+#include <mutex>
+#include <unordered_map>
+
+#include <android-base/thread_annotations.h>
+
+#include "adb_unique_fd.h"
+#include "fdevent.h"
+
+struct fdevent_context_epoll final : public fdevent_context {
+    fdevent_context_epoll();
+    virtual ~fdevent_context_epoll();
+
+    virtual void Register(fdevent* fde) final;
+    virtual void Unregister(fdevent* fde) final;
+
+    virtual void Set(fdevent* fde, unsigned events) final;
+
+    virtual void Loop() final;
+    size_t InstalledCount() final;
+
+  protected:
+    virtual void Interrupt() final;
+
+  public:
+    // All operations to fdevent should happen only in the main thread.
+    // That's why we don't need a lock for fdevent.
+    std::unordered_map<int, fdevent*> epoll_node_map_;
+    std::list<fdevent*> pending_list_;
+
+    unique_fd epoll_fd_;
+    unique_fd interrupt_fd_;
+    fdevent* interrupt_fde_ = nullptr;
+};
+
+#endif  // defined(__linux__)
diff --git a/adb/fdevent/fdevent_poll.cpp b/adb/fdevent/fdevent_poll.cpp
index 75ea081..cc4a7a1 100644
--- a/adb/fdevent/fdevent_poll.cpp
+++ b/adb/fdevent/fdevent_poll.cpp
@@ -75,60 +75,14 @@
 }
 
 fdevent_context_poll::~fdevent_context_poll() {
+    // Destroy calls virtual methods, but this class is final, so that's okay.
     this->Destroy(this->interrupt_fde_);
 }
 
-void fdevent_context_poll::Register(fdevent* fde) {
-    auto pair = poll_node_map_.emplace(fde->fd.get(), PollNode(fde));
-    CHECK(pair.second) << "install existing fd " << fde->fd.get();
-}
-
-void fdevent_context_poll::Unregister(fdevent* fde) {
-    if (fde->state & FDE_ACTIVE) {
-        poll_node_map_.erase(fde->fd.get());
-
-        if (fde->state & FDE_PENDING) {
-            pending_list_.remove(fde);
-        }
-        fde->state = 0;
-        fde->events = 0;
-    }
-}
-
 void fdevent_context_poll::Set(fdevent* fde, unsigned events) {
     CheckMainThread();
-    events &= FDE_EVENTMASK;
-    if ((fde->state & FDE_EVENTMASK) == events) {
-        return;
-    }
-    CHECK(fde->state & FDE_ACTIVE);
-
-    auto it = poll_node_map_.find(fde->fd.get());
-    CHECK(it != poll_node_map_.end());
-    PollNode& node = it->second;
-    if (events & FDE_READ) {
-        node.pollfd.events |= POLLIN;
-    } else {
-        node.pollfd.events &= ~POLLIN;
-    }
-
-    if (events & FDE_WRITE) {
-        node.pollfd.events |= POLLOUT;
-    } else {
-        node.pollfd.events &= ~POLLOUT;
-    }
-    fde->state = (fde->state & FDE_STATEMASK) | events;
-
+    fde->state = events;
     D("fdevent_set: %s, events = %u", dump_fde(fde).c_str(), events);
-
-    if (fde->state & FDE_PENDING) {
-        // If we are pending, make sure we don't signal an event that is no longer wanted.
-        fde->events &= events;
-        if (fde->events == 0) {
-            pending_list_.remove(fde);
-            fde->state &= ~FDE_PENDING;
-        }
-    }
 }
 
 static std::string dump_pollfds(const std::vector<adb_pollfd>& pollfds) {
@@ -146,204 +100,94 @@
     return result;
 }
 
-static std::optional<std::chrono::milliseconds> calculate_timeout(fdevent_context_poll* ctx) {
-    std::optional<std::chrono::milliseconds> result = std::nullopt;
-    auto now = std::chrono::steady_clock::now();
-    ctx->CheckMainThread();
-
-    for (const auto& [fd, pollnode] : ctx->poll_node_map_) {
-        UNUSED(fd);
-        auto timeout_opt = pollnode.fde->timeout;
-        if (timeout_opt) {
-            auto deadline = pollnode.fde->last_active + *timeout_opt;
-            auto time_left = std::chrono::duration_cast<std::chrono::milliseconds>(deadline - now);
-            if (time_left < std::chrono::milliseconds::zero()) {
-                time_left = std::chrono::milliseconds::zero();
-            }
-
-            if (!result) {
-                result = time_left;
-            } else {
-                result = std::min(*result, time_left);
-            }
-        }
-    }
-
-    return result;
-}
-
-static void fdevent_process(fdevent_context_poll* ctx) {
-    std::vector<adb_pollfd> pollfds;
-    for (const auto& pair : ctx->poll_node_map_) {
-        pollfds.push_back(pair.second.pollfd);
-    }
-    CHECK_GT(pollfds.size(), 0u);
-    D("poll(), pollfds = %s", dump_pollfds(pollfds).c_str());
-
-    auto timeout = calculate_timeout(ctx);
-    int timeout_ms;
-    if (!timeout) {
-        timeout_ms = -1;
-    } else {
-        timeout_ms = timeout->count();
-    }
-
-    int ret = adb_poll(&pollfds[0], pollfds.size(), timeout_ms);
-    if (ret == -1) {
-        PLOG(ERROR) << "poll(), ret = " << ret;
-        return;
-    }
-
-    auto post_poll = std::chrono::steady_clock::now();
-
-    for (const auto& pollfd : pollfds) {
-        if (pollfd.revents != 0) {
-            D("for fd %d, revents = %x", pollfd.fd, pollfd.revents);
-        }
-        unsigned events = 0;
-        if (pollfd.revents & POLLIN) {
-            events |= FDE_READ;
-        }
-        if (pollfd.revents & POLLOUT) {
-            events |= FDE_WRITE;
-        }
-        if (pollfd.revents & (POLLERR | POLLHUP | POLLNVAL)) {
-            // We fake a read, as the rest of the code assumes that errors will
-            // be detected at that point.
-            events |= FDE_READ | FDE_ERROR;
-        }
-#if defined(__linux__)
-        if (pollfd.revents & POLLRDHUP) {
-            events |= FDE_READ | FDE_ERROR;
-        }
-#endif
-        auto it = ctx->poll_node_map_.find(pollfd.fd);
-        CHECK(it != ctx->poll_node_map_.end());
-        fdevent* fde = it->second.fde;
-
-        if (events == 0) {
-            // Check for timeout.
-            if (fde->timeout) {
-                auto deadline = fde->last_active + *fde->timeout;
-                if (deadline < post_poll) {
-                    events |= FDE_TIMEOUT;
-                }
-            }
-        }
-
-        if (events != 0) {
-            CHECK_EQ(fde->fd.get(), pollfd.fd);
-            fde->events |= events;
-            fde->last_active = post_poll;
-            D("%s got events %x", dump_fde(fde).c_str(), events);
-            fde->state |= FDE_PENDING;
-            ctx->pending_list_.push_back(fde);
-        }
-    }
-}
-
-template <class T>
-struct always_false : std::false_type {};
-
-static void fdevent_call_fdfunc(fdevent* fde) {
-    unsigned events = fde->events;
-    fde->events = 0;
-    CHECK(fde->state & FDE_PENDING);
-    fde->state &= (~FDE_PENDING);
-    D("fdevent_call_fdfunc %s", dump_fde(fde).c_str());
-    std::visit(
-            [&](auto&& f) {
-                using F = std::decay_t<decltype(f)>;
-                if constexpr (std::is_same_v<fd_func, F>) {
-                    f(fde->fd.get(), events, fde->arg);
-                } else if constexpr (std::is_same_v<fd_func2, F>) {
-                    f(fde, events, fde->arg);
-                } else {
-                    static_assert(always_false<F>::value, "non-exhaustive visitor");
-                }
-            },
-            fde->func);
-}
-
-static void fdevent_check_spin(fdevent_context_poll* ctx, uint64_t cycle) {
-    // Check to see if we're spinning because we forgot about an fdevent
-    // by keeping track of how long fdevents have been continuously pending.
-    struct SpinCheck {
-        fdevent* fde;
-        android::base::boot_clock::time_point timestamp;
-        uint64_t cycle;
-    };
-
-    // TODO: Move this into the base fdevent_context.
-    static auto& g_continuously_pending = *new std::unordered_map<uint64_t, SpinCheck>();
-    static auto last_cycle = android::base::boot_clock::now();
-
-    auto now = android::base::boot_clock::now();
-    if (now - last_cycle > 10ms) {
-        // We're not spinning.
-        g_continuously_pending.clear();
-        last_cycle = now;
-        return;
-    }
-    last_cycle = now;
-
-    for (auto* fde : ctx->pending_list_) {
-        auto it = g_continuously_pending.find(fde->id);
-        if (it == g_continuously_pending.end()) {
-            g_continuously_pending[fde->id] =
-                    SpinCheck{.fde = fde, .timestamp = now, .cycle = cycle};
-        } else {
-            it->second.cycle = cycle;
-        }
-    }
-
-    for (auto it = g_continuously_pending.begin(); it != g_continuously_pending.end();) {
-        if (it->second.cycle != cycle) {
-            it = g_continuously_pending.erase(it);
-        } else {
-            // Use an absurdly long window, since all we really care about is
-            // getting a bugreport eventually.
-            if (now - it->second.timestamp > 300s) {
-                LOG(FATAL_WITHOUT_ABORT)
-                        << "detected spin in fdevent: " << dump_fde(it->second.fde);
-#if defined(__linux__)
-                int fd = it->second.fde->fd.get();
-                std::string fd_path = android::base::StringPrintf("/proc/self/fd/%d", fd);
-                std::string path;
-                if (!android::base::Readlink(fd_path, &path)) {
-                    PLOG(FATAL_WITHOUT_ABORT) << "readlink of fd " << fd << " failed";
-                }
-                LOG(FATAL_WITHOUT_ABORT) << "fd " << fd << " = " << path;
-#endif
-                abort();
-            }
-            ++it;
-        }
-    }
-}
-
 void fdevent_context_poll::Loop() {
     main_thread_id_ = android::base::GetThreadId();
 
-    uint64_t cycle = 0;
     while (true) {
         if (terminate_loop_) {
             break;
         }
 
         D("--- --- waiting for events");
+        std::vector<adb_pollfd> pollfds;
+        for (const auto& [fd, fde] : this->installed_fdevents_) {
+            adb_pollfd pfd;
+            pfd.fd = fd;
+            pfd.events = 0;
+            if (fde->state & FDE_READ) {
+                pfd.events |= POLLIN;
+            }
+            if (fde->state & FDE_WRITE) {
+                pfd.events |= POLLOUT;
+            }
+            if (fde->state & FDE_ERROR) {
+                pfd.events |= POLLERR;
+            }
+#if defined(__linux__)
+            pfd.events |= POLLRDHUP;
+#endif
+            pfd.revents = 0;
+            pollfds.push_back(pfd);
+        }
+        CHECK_GT(pollfds.size(), 0u);
+        D("poll(), pollfds = %s", dump_pollfds(pollfds).c_str());
 
-        fdevent_process(this);
-
-        fdevent_check_spin(this, cycle++);
-
-        while (!pending_list_.empty()) {
-            fdevent* fde = pending_list_.front();
-            pending_list_.pop_front();
-            fdevent_call_fdfunc(fde);
+        std::optional<std::chrono::milliseconds> timeout = CalculatePollDuration();
+        int timeout_ms;
+        if (!timeout) {
+            timeout_ms = -1;
+        } else {
+            timeout_ms = timeout->count();
         }
 
-        this->FlushRunQueue();
+        int ret = adb_poll(pollfds.data(), pollfds.size(), timeout_ms);
+        if (ret == -1) {
+            PLOG(ERROR) << "poll(), ret = " << ret;
+            return;
+        }
+
+        auto post_poll = std::chrono::steady_clock::now();
+        std::vector<fdevent_event> poll_events;
+
+        for (const auto& pollfd : pollfds) {
+            unsigned events = 0;
+            if (pollfd.revents & POLLIN) {
+                events |= FDE_READ;
+            }
+            if (pollfd.revents & POLLOUT) {
+                events |= FDE_WRITE;
+            }
+            if (pollfd.revents & (POLLERR | POLLHUP | POLLNVAL)) {
+                // We fake a read, as the rest of the code assumes that errors will
+                // be detected at that point.
+                events |= FDE_READ | FDE_ERROR;
+            }
+#if defined(__linux__)
+            if (pollfd.revents & POLLRDHUP) {
+                events |= FDE_READ | FDE_ERROR;
+            }
+#endif
+
+            auto it = this->installed_fdevents_.find(pollfd.fd);
+            CHECK(it != this->installed_fdevents_.end());
+            fdevent* fde = it->second;
+
+            if (events == 0) {
+                if (fde->timeout) {
+                    auto deadline = fde->last_active + *fde->timeout;
+                    if (deadline < post_poll) {
+                        events |= FDE_TIMEOUT;
+                    }
+                }
+            }
+
+            if (events != 0) {
+                D("%s got events %x", dump_fde(fde).c_str(), events);
+                poll_events.push_back({fde, events});
+                fde->last_active = post_poll;
+            }
+        }
+        this->HandleEvents(std::move(poll_events));
     }
 
     main_thread_id_.reset();
@@ -351,7 +195,7 @@
 
 size_t fdevent_context_poll::InstalledCount() {
     // We always have an installed fde for interrupt.
-    return poll_node_map_.size() - 1;
+    return this->installed_fdevents_.size() - 1;
 }
 
 void fdevent_context_poll::Interrupt() {
diff --git a/adb/fdevent/fdevent_poll.h b/adb/fdevent/fdevent_poll.h
index db08301..98abab2 100644
--- a/adb/fdevent/fdevent_poll.h
+++ b/adb/fdevent/fdevent_poll.h
@@ -44,13 +44,10 @@
   }
 };
 
-struct fdevent_context_poll : public fdevent_context {
+struct fdevent_context_poll final : public fdevent_context {
     fdevent_context_poll();
     virtual ~fdevent_context_poll();
 
-    virtual void Register(fdevent* fde) final;
-    virtual void Unregister(fdevent* fde) final;
-
     virtual void Set(fdevent* fde, unsigned events) final;
 
     virtual void Loop() final;
@@ -61,11 +58,6 @@
     virtual void Interrupt() final;
 
   public:
-    // All operations to fdevent should happen only in the main thread.
-    // That's why we don't need a lock for fdevent.
-    std::unordered_map<int, PollNode> poll_node_map_;
-    std::list<fdevent*> pending_list_;
-
     unique_fd interrupt_fd_;
     fdevent* interrupt_fde_ = nullptr;
 };
diff --git a/adb/fdevent/fdevent_test.cpp b/adb/fdevent/fdevent_test.cpp
index 682f061..e06b3b3 100644
--- a/adb/fdevent/fdevent_test.cpp
+++ b/adb/fdevent/fdevent_test.cpp
@@ -118,8 +118,8 @@
 TEST_F(FdeventTest, smoke) {
     for (bool use_new_callback : {true, false}) {
         fdevent_reset();
-        const size_t PIPE_COUNT = 10;
-        const size_t MESSAGE_LOOP_COUNT = 100;
+        const size_t PIPE_COUNT = 512;
+        const size_t MESSAGE_LOOP_COUNT = 10;
         const std::string MESSAGE = "fdevent_test";
         int fd_pair1[2];
         int fd_pair2[2];
@@ -172,44 +172,6 @@
     }
 }
 
-struct InvalidFdArg {
-    fdevent* fde;
-    unsigned expected_events;
-    size_t* happened_event_count;
-};
-
-static void InvalidFdEventCallback(int, unsigned events, void* userdata) {
-    InvalidFdArg* arg = reinterpret_cast<InvalidFdArg*>(userdata);
-    ASSERT_EQ(arg->expected_events, events);
-    fdevent_destroy(arg->fde);
-    if (++*(arg->happened_event_count) == 2) {
-        fdevent_terminate_loop();
-    }
-}
-
-static void InvalidFdThreadFunc() {
-    const int INVALID_READ_FD = std::numeric_limits<int>::max() - 1;
-    size_t happened_event_count = 0;
-    InvalidFdArg read_arg;
-    read_arg.expected_events = FDE_READ | FDE_ERROR;
-    read_arg.happened_event_count = &happened_event_count;
-    read_arg.fde = fdevent_create(INVALID_READ_FD, InvalidFdEventCallback, &read_arg);
-    fdevent_add(read_arg.fde, FDE_READ);
-
-    const int INVALID_WRITE_FD = std::numeric_limits<int>::max();
-    InvalidFdArg write_arg;
-    write_arg.expected_events = FDE_READ | FDE_ERROR;
-    write_arg.happened_event_count = &happened_event_count;
-    write_arg.fde = fdevent_create(INVALID_WRITE_FD, InvalidFdEventCallback, &write_arg);
-    fdevent_add(write_arg.fde, FDE_WRITE);
-    fdevent_loop();
-}
-
-TEST_F(FdeventTest, invalid_fd) {
-    std::thread thread(InvalidFdThreadFunc);
-    thread.join();
-}
-
 TEST_F(FdeventTest, run_on_main_thread) {
     std::vector<int> vec;
 
diff --git a/fs_mgr/fs_mgr_dm_linear.cpp b/fs_mgr/fs_mgr_dm_linear.cpp
index eaa515a..1b85b47 100644
--- a/fs_mgr/fs_mgr_dm_linear.cpp
+++ b/fs_mgr/fs_mgr_dm_linear.cpp
@@ -52,29 +52,36 @@
 using DmTargetZero = android::dm::DmTargetZero;
 using DmTargetLinear = android::dm::DmTargetLinear;
 
-static bool GetPhysicalPartitionDevicePath(const LpMetadata& metadata,
+static bool GetPhysicalPartitionDevicePath(const IPartitionOpener& opener,
+                                           const LpMetadata& metadata,
                                            const LpMetadataBlockDevice& block_device,
-                                           const std::string& super_device,
-                                           std::string* result) {
-    // Note: device-mapper will not accept symlinks, so we must use realpath
-    // here.
-    std::string name = GetBlockDevicePartitionName(block_device);
-    std::string path = "/dev/block/by-name/" + name;
+                                           const std::string& super_device, std::string* result) {
     // If the super device is the source of this block device's metadata,
     // make sure we use the correct super device (and not just "super",
     // which might not exist.)
+    std::string name = GetBlockDevicePartitionName(block_device);
+    std::string dev_string = opener.GetDeviceString(name);
     if (GetMetadataSuperBlockDevice(metadata) == &block_device) {
-        path = super_device;
+        dev_string = opener.GetDeviceString(super_device);
     }
-    if (!android::base::Realpath(path, result)) {
-        PERROR << "realpath: " << path;
-        return false;
+
+    // Note: device-mapper will not accept symlinks, so we must use realpath
+    // here. If the device string is a major:minor sequence, we don't need to
+    // to call Realpath (it would not work anyway).
+    if (android::base::StartsWith(dev_string, "/")) {
+        if (!android::base::Realpath(dev_string, result)) {
+            PERROR << "realpath: " << dev_string;
+            return false;
+        }
+    } else {
+        *result = dev_string;
     }
     return true;
 }
 
-static bool CreateDmTable(const LpMetadata& metadata, const LpMetadataPartition& partition,
-                          const std::string& super_device, DmTable* table) {
+static bool CreateDmTable(const IPartitionOpener& opener, const LpMetadata& metadata,
+                          const LpMetadataPartition& partition, const std::string& super_device,
+                          DmTable* table) {
     uint64_t sector = 0;
     for (size_t i = 0; i < partition.num_extents; i++) {
         const auto& extent = metadata.extents[partition.first_extent_index + i];
@@ -85,12 +92,13 @@
                 break;
             case LP_TARGET_TYPE_LINEAR: {
                 const auto& block_device = metadata.block_devices[extent.target_source];
-                std::string path;
-                if (!GetPhysicalPartitionDevicePath(metadata, block_device, super_device, &path)) {
+                std::string dev_string;
+                if (!GetPhysicalPartitionDevicePath(opener, metadata, block_device, super_device,
+                                                    &dev_string)) {
                     LOG(ERROR) << "Unable to complete device-mapper table, unknown block device";
                     return false;
                 }
-                target = std::make_unique<DmTargetLinear>(sector, extent.num_sectors, path,
+                target = std::make_unique<DmTargetLinear>(sector, extent.num_sectors, dev_string,
                                                           extent.target_data);
                 break;
             }
@@ -179,8 +187,12 @@
         }
     }
 
+    PartitionOpener default_opener;
+    const IPartitionOpener* opener =
+            params.partition_opener ? params.partition_opener : &default_opener;
+
     DmTable table;
-    if (!CreateDmTable(*metadata, *partition, params.block_device, &table)) {
+    if (!CreateDmTable(*opener, *metadata, *partition, params.block_device, &table)) {
         return false;
     }
     if (params.force_writable) {
diff --git a/fs_mgr/include/fs_mgr_dm_linear.h b/fs_mgr/include/fs_mgr_dm_linear.h
index 6eb541c..8e2fdbb 100644
--- a/fs_mgr/include/fs_mgr_dm_linear.h
+++ b/fs_mgr/include/fs_mgr_dm_linear.h
@@ -73,6 +73,10 @@
     // If this is non-empty, it will override the device mapper name (by
     // default the partition name will be used).
     std::string device_name;
+
+    // If non-null, this will use the specified IPartitionOpener rather than
+    // the default one.
+    const IPartitionOpener* partition_opener = nullptr;
 };
 
 bool CreateLogicalPartition(const CreateLogicalPartitionParams& params, std::string* path);
diff --git a/fs_mgr/libdm/dm.cpp b/fs_mgr/libdm/dm.cpp
index a4e0d76..e7a3ff2 100644
--- a/fs_mgr/libdm/dm.cpp
+++ b/fs_mgr/libdm/dm.cpp
@@ -79,6 +79,13 @@
     return true;
 }
 
+bool DeviceMapper::DeleteDeviceIfExists(const std::string& name) {
+    if (GetState(name) == DmDeviceState::INVALID) {
+        return true;
+    }
+    return DeleteDevice(name);
+}
+
 bool DeviceMapper::DeleteDevice(const std::string& name) {
     struct dm_ioctl io;
     InitIo(&io, name);
diff --git a/fs_mgr/libdm/include/libdm/dm.h b/fs_mgr/libdm/include/libdm/dm.h
index cf306f3..e25ce7f 100644
--- a/fs_mgr/libdm/include/libdm/dm.h
+++ b/fs_mgr/libdm/include/libdm/dm.h
@@ -89,6 +89,7 @@
     // Removes a device mapper device with the given name.
     // Returns 'true' on success, false otherwise.
     bool DeleteDevice(const std::string& name);
+    bool DeleteDeviceIfExists(const std::string& name);
 
     // Fetches and returns the complete state of the underlying device mapper
     // device with given name.
diff --git a/fs_mgr/liblp/include/liblp/partition_opener.h b/fs_mgr/liblp/include/liblp/partition_opener.h
index e506bd5..7c9100b 100644
--- a/fs_mgr/liblp/include/liblp/partition_opener.h
+++ b/fs_mgr/liblp/include/liblp/partition_opener.h
@@ -62,6 +62,11 @@
     // Return block device information about the given named physical partition.
     // The name can be an absolute path if the full path is already known.
     virtual bool GetInfo(const std::string& partition_name, BlockDeviceInfo* info) const = 0;
+
+    // Return a path that can be used to pass the block device to device-mapper.
+    // This must either result in an absolute path, or a major:minor device
+    // sequence.
+    virtual std::string GetDeviceString(const std::string& partition_name) const = 0;
 };
 
 // Helper class to implement IPartitionOpener. If |partition_name| is not an
@@ -71,6 +76,7 @@
     virtual android::base::unique_fd Open(const std::string& partition_name,
                                           int flags) const override;
     virtual bool GetInfo(const std::string& partition_name, BlockDeviceInfo* info) const override;
+    virtual std::string GetDeviceString(const std::string& partition_name) const override;
 };
 
 }  // namespace fs_mgr
diff --git a/fs_mgr/liblp/partition_opener.cpp b/fs_mgr/liblp/partition_opener.cpp
index cc4a882..f1e8fc2 100644
--- a/fs_mgr/liblp/partition_opener.cpp
+++ b/fs_mgr/liblp/partition_opener.cpp
@@ -100,5 +100,9 @@
     return GetBlockDeviceInfo(path, info);
 }
 
+std::string PartitionOpener::GetDeviceString(const std::string& partition_name) const {
+    return GetPartitionAbsolutePath(partition_name);
+}
+
 }  // namespace fs_mgr
 }  // namespace android