commit 4bc561caa5062c43ab7c4f0b681717e8f6e315bd
author Siarhei Vishniakou <svv@google.com> Fri Nov 02 17:41:58 2018 -0700
committer Siarhei Vishniakou <svv@google.com> Fri Nov 02 18:04:22 2018 -0700
tree fb265236bdb64dbed2ba5b3476f56e47aa15fb34
parent 6bdb3cac812cf8fabcb90f71d624d9b4a3776069

Look up devices by fd

Instead of storing deviceIndex inside epoll_data_t in the epoll_event,
store the file descriptors instead. Since we already have the file
descriptors for wake pipe and inotify, we can avoid storing magic
numbers. More importantly, this allows us to add video device
monitoring. For video devices, the old approach would no longer work,
because the same device index would apply to both video device file
descriptor and the input device file descriptor.
By storing the file descriptor, we can differentiate between the two
portions of the same EventHub::Device.

Test: atest inputflinger_tests libinput_tests
Test: touch interaction with the booted phone
Bug: 111480215
Change-Id: Iadb95f2b14499d600167c89f86fde5db82608af0

services/inputflinger/EventHub.cpp

diff --git a/services/inputflinger/EventHub.cpp b/services/inputflinger/EventHub.cpp
index a964d29..aab83ea 100644
--- a/services/inputflinger/EventHub.cpp
+++ b/services/inputflinger/EventHub.cpp
@@ -193,8 +193,6 @@
 
 // --- EventHub ---
 
-const uint32_t EventHub::EPOLL_ID_INOTIFY;
-const uint32_t EventHub::EPOLL_ID_WAKE;
 const int EventHub::EPOLL_SIZE_HINT;
 const int EventHub::EPOLL_MAX_EVENTS;
 
@@ -217,7 +215,7 @@
     struct epoll_event eventItem;
     memset(&eventItem, 0, sizeof(eventItem));
     eventItem.events = EPOLLIN;
-    eventItem.data.u32 = EPOLL_ID_INOTIFY;
+    eventItem.data.fd = mINotifyFd;
     result = epoll_ctl(mEpollFd, EPOLL_CTL_ADD, mINotifyFd, &eventItem);
     LOG_ALWAYS_FATAL_IF(result != 0, "Could not add INotify to epoll instance.  errno=%d", errno);
 
@@ -236,7 +234,7 @@
     LOG_ALWAYS_FATAL_IF(result != 0, "Could not make wake write pipe non-blocking.  errno=%d",
             errno);
 
-    eventItem.data.u32 = EPOLL_ID_WAKE;
+    eventItem.data.fd = mWakeReadPipeFd;
     result = epoll_ctl(mEpollFd, EPOLL_CTL_ADD, mWakeReadPipeFd, &eventItem);
     LOG_ALWAYS_FATAL_IF(result != 0, "Could not add wake read pipe to epoll instance.  errno=%d",
             errno);
@@ -735,6 +733,16 @@
     return nullptr;
 }
 
+EventHub::Device* EventHub::getDeviceByFdLocked(int fd) const {
+    for (size_t i = 0; i < mDevices.size(); i++) {
+        Device* device = mDevices.valueAt(i);
+        if (device->fd == fd) {
+            return device;
+        }
+    }
+    return nullptr;
+}
+
 size_t EventHub::getEvents(int timeoutMillis, RawEvent* buffer, size_t bufferSize) {
     ALOG_ASSERT(bufferSize >= 1);
 
@@ -811,7 +819,7 @@
         bool deviceChanged = false;
         while (mPendingEventIndex < mPendingEventCount) {
             const struct epoll_event& eventItem = mPendingEventItems[mPendingEventIndex++];
-            if (eventItem.data.u32 == EPOLL_ID_INOTIFY) {
+            if (eventItem.data.fd == mINotifyFd) {
                 if (eventItem.events & EPOLLIN) {
                     mPendingINotify = true;
                 } else {
@@ -820,7 +828,7 @@
                 continue;
             }
 
-            if (eventItem.data.u32 == EPOLL_ID_WAKE) {
+            if (eventItem.data.fd == mWakeReadPipeFd) {
                 if (eventItem.events & EPOLLIN) {
                     ALOGV("awoken after wake()");
                     awoken = true;
@@ -836,14 +844,13 @@
                 continue;
             }
 
-            ssize_t deviceIndex = mDevices.indexOfKey(eventItem.data.u32);
-            if (deviceIndex < 0) {
-                ALOGW("Received unexpected epoll event 0x%08x for unknown device id %d.",
-                        eventItem.events, eventItem.data.u32);
+            Device* device = getDeviceByFdLocked(eventItem.data.fd);
+            if (device == nullptr) {
+                ALOGW("Received unexpected epoll event 0x%08x for unknown device fd %d.",
+                        eventItem.events, eventItem.data.fd);
                 continue;
             }
 
-            Device* device = mDevices.valueAt(deviceIndex);
             if (eventItem.events & EPOLLIN) {
                 int32_t readSize = read(device->fd, readBuffer,
                         sizeof(struct input_event) * capacity);
@@ -1089,7 +1096,7 @@
     if (mUsingEpollWakeup) {
         eventItem.events |= EPOLLWAKEUP;
     }
-    eventItem.data.u32 = device->id;
+    eventItem.data.fd = device->fd;
     if (epoll_ctl(mEpollFd, EPOLL_CTL_ADD, device->fd, &eventItem)) {
         ALOGE("Could not add device fd to epoll instance.  errno=%d", errno);
         return -errno;