[wpe] Fix glib main loop integration

GLib main loop may have multiple sources attached with
same file descriptor but different event mask and they may get
added and removed multiple times independently. Android looper
handles only one file descriptor per event set and if file descriptor
that already exists in looper gets added again with different event set
then existing polling event is updated. Thus we must combine masks from
all duplicate FDs from GLib main loop for ALooper.

wpe/src/main/cpp/Runtime/MessagePump.cpp

@@ -86,6 +86,7 @@ MessagePump::MessagePump()
             read(fileDesc, &value, sizeof(value));
 
             auto* pump = reinterpret_cast<MessagePump*>(userData);
+            pump->m_pendingDispatch = false;
             pump->dispatch();
             pump->prepare();
 
@@ -102,9 +103,9 @@ MessagePump::~MessagePump()
 {
     flush();
 
-    for (const int fileDesc : m_looperAttachedPollFds)
-        ALooper_removeFd(m_looper, fileDesc);
-    m_looperAttachedPollFds.clear();
+    for (const auto& pollFD : m_looperFdEvents)
+        ALooper_removeFd(m_looper, pollFD.first);
+    m_looperFdEvents.clear();
 
     m_pollFdsSize = 0;
     m_pollFdsCapacity = 0;
@@ -124,7 +125,7 @@ MessagePump::~MessagePump()
     m_dispatchFd = 0;
 }
 
-void MessagePump::flush() const
+void MessagePump::flush() const noexcept
 {
     // Clear the eventfd and reset its counter to 0
     int64_t value = 0;
@@ -159,7 +160,7 @@ void MessagePump::invoke(void (*onExec)(void*), void (*onDestroy)(void*), void*
         });
 }
 
-void MessagePump::prepare()
+void MessagePump::prepare() noexcept
 {
     g_main_context_prepare(m_context, &m_maxPriority);
 
@@ -176,39 +177,81 @@ void MessagePump::prepare()
         m_pollFds = g_new(GPollFD, m_pollFdsCapacity);
     }
 
-    std::set<int> unusedAttachedFds = m_looperAttachedPollFds;
-    for (int i = 0; i < m_pollFdsSize; ++i) {
-        GPollFD& pollFd = m_pollFds[i];
-        pollFd.revents = 0;
-        unusedAttachedFds.erase(pollFd.fd);
-
-        if (m_looperAttachedPollFds.find(pollFd.fd) == m_looperAttachedPollFds.end()) {
-            m_looperAttachedPollFds.emplace(pollFd.fd);
-            ALooper_addFd(
-                m_looper, pollFd.fd, ALOOPER_POLL_CALLBACK,
-                static_cast<int>(glibEventsToLooperEvents(pollFd.events) | ALOOPER_EVENT_OUTPUT),
-                +[](int fileDesc, int events, void* userData) -> int {
-                    auto* pump = reinterpret_cast<MessagePump*>(userData);
-                    for (int j = 0; j < pump->m_pollFdsSize; ++j) {
-                        if (pump->m_pollFds[j].fd == fileDesc) {
-                            pump->m_pollFds[j].revents = looperEventsToGLibEvents(events);
-                            break;
-                        }
+    std::vector<GPollFD> changedPollFDs;
+    std::vector<int> removedFds;
+    collectPollFDChanges(m_pollFds, m_pollFdsSize, changedPollFDs, removedFds);
+
+    for (const auto& pollFD : changedPollFDs) {
+        ALooper_addFd(
+            m_looper, pollFD.fd, ALOOPER_POLL_CALLBACK,
+            static_cast<int>(glibEventsToLooperEvents(pollFD.events) | ALOOPER_EVENT_OUTPUT),
+            +[](int fileDesc, int events, void* userData) -> int {
+                auto* pump = reinterpret_cast<MessagePump*>(userData);
+                for (int j = 0; j < pump->m_pollFdsSize; ++j) {
+                    if (pump->m_pollFds[j].fd == fileDesc) {
+                        pump->m_pollFds[j].revents = looperEventsToGLibEvents(events);
+                        break;
                     }
+                }
+                pump->scheduleDispatch();
+                return 1; // Continue listening for events
+            },
+            reinterpret_cast<void*>(this));
+    }
+
+    for (const auto& fd : removedFds) {
+        ALooper_removeFd(m_looper, fd);
+    }
+}
+
+void MessagePump::collectPollFDChanges(
+    const GPollFD* pollFDs, int numPollFDs, std::vector<GPollFD>& changedPollFDs, std::vector<int>& removedFds) noexcept
+{
+    std::unordered_map<int, int> currFdEvents; // Current fd to mask map
 
-                    // Schedule dispatching
-                    uint64_t value = 1;
-                    write(pump->m_dispatchFd, &value, sizeof(value));
+    // Build currFdMask by combining masks for the same fd
+    for (int i = 0; i < numPollFDs; ++i) {
+        int fd = pollFDs[i].fd;
+        gushort events = pollFDs[i].events;
+        currFdEvents[fd] |= events;
+    }
 
-                    return 1; // Continue listening for events
-                },
-                reinterpret_cast<void*>(this));
+    // Detect changes and new fds
+    for (const auto& kv : currFdEvents) {
+        int fd = kv.first;
+        gushort events = kv.second;
+
+        auto it = m_looperFdEvents.find(fd);
+        if (it == m_looperFdEvents.end()) {
+            // New fd detected
+            GPollFD e {fd, events, 0};
+            changedPollFDs.push_back(e);
+        } else if (events != it->second) {
+            // Events has changed
+            GPollFD e {fd, events, 0};
+            changedPollFDs.push_back(e);
+        }
+    }
+
+    // Detect removed fds
+    for (const auto& kv : m_looperFdEvents) {
+        int fd = kv.first;
+        if (currFdEvents.find(fd) == currFdEvents.end()) {
+            // fd was in previous but not in current
+            removedFds.push_back(fd);
         }
     }
 
-    for (const int fileDesc : unusedAttachedFds) {
-        ALooper_removeFd(m_looper, fileDesc);
-        m_looperAttachedPollFds.erase(fileDesc);
+    // Update m_looperFdEvents for the next call
+    m_looperFdEvents = currFdEvents;
+}
+
+void MessagePump::scheduleDispatch() noexcept
+{
+    if (!m_pendingDispatch) {
+        uint64_t value = 1;
+        write(m_dispatchFd, &value, sizeof(value));
+        m_pendingDispatch = true;
     }
 }
 

wpe/src/main/cpp/Runtime/MessagePump.h

@@ -22,7 +22,8 @@
 
 #include <android/looper.h>
 #include <glib.h>
-#include <set>
+#include <unordered_map>
+#include <vector>
 
 class MessagePump final {
 public:
@@ -35,14 +36,18 @@ class MessagePump final {
 
     ~MessagePump();
 
-    void flush() const;
+    void flush() const noexcept;
     void invoke(void (*onExec)(void*), void (*onDestroy)(void*), void* userData) const noexcept;
 
 private:
-    void prepare();
+    void prepare() noexcept;
+    void collectPollFDChanges(const GPollFD* pollFDs, int numPollFDs, std::vector<GPollFD>& changedPollFDs,
+        std::vector<int>& removedPollFDs) noexcept;
+    void scheduleDispatch() noexcept;
     void dispatch() const noexcept;
 
     int m_dispatchFd = 0;
+    bool m_pendingDispatch = false;
     ALooper* m_looper = nullptr;
 
     GMainContext* m_context = nullptr;
@@ -51,5 +56,5 @@ class MessagePump final {
     gint m_pollFdsSize = 0;
     gint m_pollFdsCapacity = 0;
 
-    std::set<int> m_looperAttachedPollFds {};
+    std::unordered_map<int, int> m_looperFdEvents {};
 };