Replace epoll() with poll() and rename PollLoop to Looper.
As part of this change, consolidated and cleaned up the Looper API so
that there are fewer distinctions between the NDK and non-NDK declarations
(no need for two callback types, etc.).
Removed the dependence on specific constants from sys/poll.h such as
POLLIN. Instead looper.h defines events like LOOPER_EVENT_INPUT for
the events that it supports. That should help make any future
under-the-hood implementation changes easier.
Fixed a couple of compiler warnings along the way.
Change-Id: I449a7ec780bf061bdd325452f823673e2b39b6ae
diff --git a/libs/utils/Looper.cpp b/libs/utils/Looper.cpp
new file mode 100644
index 0000000..fd287da
--- /dev/null
+++ b/libs/utils/Looper.cpp
@@ -0,0 +1,368 @@
+//
+// Copyright 2010 The Android Open Source Project
+//
+// A looper implementation based on epoll().
+//
+#define LOG_TAG "Looper"
+
+//#define LOG_NDEBUG 0
+
+// Debugs poll and wake interactions.
+#define DEBUG_POLL_AND_WAKE 0
+
+// Debugs callback registration and invocation.
+#define DEBUG_CALLBACKS 0
+
+#include <cutils/log.h>
+#include <utils/Looper.h>
+#include <utils/Timers.h>
+
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/epoll.h>
+
+
+namespace android {
+
+static pthread_mutex_t gTLSMutex = PTHREAD_MUTEX_INITIALIZER;
+static bool gHaveTLS = false;
+static pthread_key_t gTLS = 0;
+
+// Hint for number of file descriptors to be associated with the epoll instance.
+static const int EPOLL_SIZE_HINT = 8;
+
+// Maximum number of file descriptors for which to retrieve poll events each iteration.
+static const int EPOLL_MAX_EVENTS = 16;
+
+Looper::Looper(bool allowNonCallbacks) :
+ mAllowNonCallbacks(allowNonCallbacks),
+ mResponseIndex(0) {
+ mEpollFd = epoll_create(EPOLL_SIZE_HINT);
+ LOG_ALWAYS_FATAL_IF(mEpollFd < 0, "Could not create epoll instance. errno=%d", errno);
+
+ int wakeFds[2];
+ int result = pipe(wakeFds);
+ LOG_ALWAYS_FATAL_IF(result != 0, "Could not create wake pipe. errno=%d", errno);
+
+ mWakeReadPipeFd = wakeFds[0];
+ mWakeWritePipeFd = wakeFds[1];
+
+ result = fcntl(mWakeReadPipeFd, F_SETFL, O_NONBLOCK);
+ LOG_ALWAYS_FATAL_IF(result != 0, "Could not make wake read pipe non-blocking. errno=%d",
+ errno);
+
+ result = fcntl(mWakeWritePipeFd, F_SETFL, O_NONBLOCK);
+ LOG_ALWAYS_FATAL_IF(result != 0, "Could not make wake write pipe non-blocking. errno=%d",
+ errno);
+
+ struct epoll_event eventItem;
+ eventItem.events = EPOLLIN;
+ 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);
+}
+
+Looper::~Looper() {
+ close(mWakeReadPipeFd);
+ close(mWakeWritePipeFd);
+ close(mEpollFd);
+}
+
+void Looper::threadDestructor(void *st) {
+ Looper* const self = static_cast<Looper*>(st);
+ if (self != NULL) {
+ self->decStrong((void*)threadDestructor);
+ }
+}
+
+void Looper::setForThread(const sp<Looper>& looper) {
+ sp<Looper> old = getForThread(); // also has side-effect of initializing TLS
+
+ if (looper != NULL) {
+ looper->incStrong((void*)threadDestructor);
+ }
+
+ pthread_setspecific(gTLS, looper.get());
+
+ if (old != NULL) {
+ old->decStrong((void*)threadDestructor);
+ }
+}
+
+sp<Looper> Looper::getForThread() {
+ if (!gHaveTLS) {
+ pthread_mutex_lock(&gTLSMutex);
+ if (pthread_key_create(&gTLS, threadDestructor) != 0) {
+ pthread_mutex_unlock(&gTLSMutex);
+ return NULL;
+ }
+ gHaveTLS = true;
+ pthread_mutex_unlock(&gTLSMutex);
+ }
+
+ return (Looper*)pthread_getspecific(gTLS);
+}
+
+sp<Looper> Looper::prepare(int opts) {
+ bool allowNonCallbacks = opts & ALOOPER_PREPARE_ALLOW_NON_CALLBACKS;
+ sp<Looper> looper = Looper::getForThread();
+ if (looper == NULL) {
+ looper = new Looper(allowNonCallbacks);
+ Looper::setForThread(looper);
+ }
+ if (looper->getAllowNonCallbacks() != allowNonCallbacks) {
+ LOGW("Looper already prepared for this thread with a different value for the "
+ "ALOOPER_PREPARE_ALLOW_NON_CALLBACKS option.");
+ }
+ return looper;
+}
+
+bool Looper::getAllowNonCallbacks() const {
+ return mAllowNonCallbacks;
+}
+
+int Looper::pollOnce(int timeoutMillis, int* outFd, int* outEvents, void** outData) {
+ int result = 0;
+ for (;;) {
+ while (mResponseIndex < mResponses.size()) {
+ const Response& response = mResponses.itemAt(mResponseIndex++);
+ if (! response.request.callback) {
+#if DEBUG_POLL_AND_WAKE
+ LOGD("%p ~ pollOnce - returning signalled identifier %d: "
+ "fd=%d, events=0x%x, data=%p", this,
+ response.request.ident, response.request.fd,
+ response.events, response.request.data);
+#endif
+ if (outFd != NULL) *outFd = response.request.fd;
+ if (outEvents != NULL) *outEvents = response.events;
+ if (outData != NULL) *outData = response.request.data;
+ return response.request.ident;
+ }
+ }
+
+ if (result != 0) {
+#if DEBUG_POLL_AND_WAKE
+ LOGD("%p ~ pollOnce - returning result %d", this, result);
+#endif
+ if (outFd != NULL) *outFd = 0;
+ if (outEvents != NULL) *outEvents = NULL;
+ if (outData != NULL) *outData = NULL;
+ return result;
+ }
+
+ result = pollInner(timeoutMillis);
+ }
+}
+
+int Looper::pollInner(int timeoutMillis) {
+#if DEBUG_POLL_AND_WAKE
+ LOGD("%p ~ pollOnce - waiting: timeoutMillis=%d", this, timeoutMillis);
+#endif
+ struct epoll_event eventItems[EPOLL_MAX_EVENTS];
+ int eventCount = epoll_wait(mEpollFd, eventItems, EPOLL_MAX_EVENTS, timeoutMillis);
+ if (eventCount < 0) {
+ if (errno != EINTR) {
+ LOGW("Poll failed with an unexpected error, errno=%d", errno);
+ }
+ return ALOOPER_POLL_ERROR;
+ }
+
+ if (eventCount == 0) {
+#if DEBUG_POLL_AND_WAKE
+ LOGD("%p ~ pollOnce - timeout", this);
+#endif
+ return ALOOPER_POLL_TIMEOUT;
+ }
+
+ int result = ALOOPER_POLL_WAKE;
+ mResponses.clear();
+ mResponseIndex = 0;
+
+#if DEBUG_POLL_AND_WAKE
+ LOGD("%p ~ pollOnce - handling events from %d fds", this, eventCount);
+#endif
+ { // acquire lock
+ AutoMutex _l(mLock);
+ for (int i = 0; i < eventCount; i++) {
+ int fd = eventItems[i].data.fd;
+ uint32_t epollEvents = eventItems[i].events;
+ if (fd == mWakeReadPipeFd) {
+ if (epollEvents & EPOLLIN) {
+#if DEBUG_POLL_AND_WAKE
+ LOGD("%p ~ pollOnce - awoken", this);
+#endif
+ char buffer[16];
+ ssize_t nRead;
+ do {
+ nRead = read(mWakeReadPipeFd, buffer, sizeof(buffer));
+ } while (nRead == sizeof(buffer));
+ } else {
+ LOGW("Ignoring unexpected epoll events 0x%x on wake read pipe.", epollEvents);
+ }
+ } else {
+ ssize_t requestIndex = mRequests.indexOfKey(fd);
+ if (requestIndex >= 0) {
+ int events = 0;
+ if (epollEvents & EPOLLIN) events |= ALOOPER_EVENT_INPUT;
+ if (epollEvents & EPOLLOUT) events |= ALOOPER_EVENT_OUTPUT;
+ if (epollEvents & EPOLLERR) events |= ALOOPER_EVENT_ERROR;
+ if (epollEvents & EPOLLHUP) events |= ALOOPER_EVENT_HANGUP;
+
+ Response response;
+ response.events = events;
+ response.request = mRequests.valueAt(requestIndex);
+ mResponses.push(response);
+ } else {
+ LOGW("Ignoring unexpected epoll events 0x%x on fd %d that is "
+ "no longer registered.", epollEvents, fd);
+ }
+ }
+ }
+ }
+
+ for (size_t i = 0; i < mResponses.size(); i++) {
+ const Response& response = mResponses.itemAt(i);
+ if (response.request.callback) {
+#if DEBUG_POLL_AND_WAKE || DEBUG_CALLBACKS
+ LOGD("%p ~ pollOnce - invoking callback: fd=%d, events=0x%x, data=%p", this,
+ response.request.fd, response.events, response.request.data);
+#endif
+ int callbackResult = response.request.callback(
+ response.request.fd, response.events, response.request.data);
+ if (callbackResult == 0) {
+ removeFd(response.request.fd);
+ }
+
+ result = ALOOPER_POLL_CALLBACK;
+ }
+ }
+ return result;
+}
+
+int Looper::pollAll(int timeoutMillis, int* outFd, int* outEvents, void** outData) {
+ if (timeoutMillis <= 0) {
+ int result;
+ do {
+ result = pollOnce(timeoutMillis, outFd, outEvents, outData);
+ } while (result == ALOOPER_POLL_CALLBACK);
+ return result;
+ } else {
+ nsecs_t endTime = systemTime(SYSTEM_TIME_MONOTONIC)
+ + milliseconds_to_nanoseconds(timeoutMillis);
+
+ for (;;) {
+ int result = pollOnce(timeoutMillis, outFd, outEvents, outData);
+ if (result != ALOOPER_POLL_CALLBACK) {
+ return result;
+ }
+
+ nsecs_t timeoutNanos = endTime - systemTime(SYSTEM_TIME_MONOTONIC);
+ if (timeoutNanos <= 0) {
+ return ALOOPER_POLL_TIMEOUT;
+ }
+
+ timeoutMillis = int(nanoseconds_to_milliseconds(timeoutNanos + 999999LL));
+ }
+ }
+}
+
+void Looper::wake() {
+#if DEBUG_POLL_AND_WAKE
+ LOGD("%p ~ wake", this);
+#endif
+
+ ssize_t nWrite = write(mWakeWritePipeFd, "W", 1);
+ if (nWrite != 1) {
+ if (errno != EAGAIN) {
+ LOGW("Could not write wake signal, errno=%d", errno);
+ }
+ }
+}
+
+int Looper::addFd(int fd, int ident, int events, ALooper_callbackFunc callback, void* data) {
+#if DEBUG_CALLBACKS
+ LOGD("%p ~ addFd - fd=%d, ident=%d, events=0x%x, callback=%p, data=%p", this, fd, ident,
+ events, callback, data);
+#endif
+
+ int epollEvents = 0;
+ if (events & ALOOPER_EVENT_INPUT) epollEvents |= EPOLLIN;
+ if (events & ALOOPER_EVENT_OUTPUT) epollEvents |= EPOLLOUT;
+ if (events & ALOOPER_EVENT_ERROR) epollEvents |= EPOLLERR;
+ if (events & ALOOPER_EVENT_HANGUP) epollEvents |= EPOLLHUP;
+
+ if (epollEvents == 0) {
+ LOGE("Invalid attempt to set a callback with no selected poll events.");
+ return -1;
+ }
+
+ if (! callback) {
+ if (! mAllowNonCallbacks) {
+ LOGE("Invalid attempt to set NULL callback but not allowed for this looper.");
+ return -1;
+ }
+
+ if (ident < 0) {
+ LOGE("Invalid attempt to set NULL callback with ident <= 0.");
+ return -1;
+ }
+ }
+
+ { // acquire lock
+ AutoMutex _l(mLock);
+
+ Request request;
+ request.fd = fd;
+ request.ident = ident;
+ request.callback = callback;
+ request.data = data;
+
+ struct epoll_event eventItem;
+ eventItem.events = epollEvents;
+ eventItem.data.fd = fd;
+
+ ssize_t requestIndex = mRequests.indexOfKey(fd);
+ if (requestIndex < 0) {
+ int epollResult = epoll_ctl(mEpollFd, EPOLL_CTL_ADD, fd, & eventItem);
+ if (epollResult < 0) {
+ LOGE("Error adding epoll events for fd %d, errno=%d", fd, errno);
+ return -1;
+ }
+ mRequests.add(fd, request);
+ } else {
+ int epollResult = epoll_ctl(mEpollFd, EPOLL_CTL_MOD, fd, & eventItem);
+ if (epollResult < 0) {
+ LOGE("Error modifying epoll events for fd %d, errno=%d", fd, errno);
+ return -1;
+ }
+ mRequests.replaceValueAt(requestIndex, request);
+ }
+ } // release lock
+ return 1;
+}
+
+int Looper::removeFd(int fd) {
+#if DEBUG_CALLBACKS
+ LOGD("%p ~ removeFd - fd=%d", this, fd);
+#endif
+
+ { // acquire lock
+ AutoMutex _l(mLock);
+ ssize_t requestIndex = mRequests.indexOfKey(fd);
+ if (requestIndex < 0) {
+ return 0;
+ }
+
+ int epollResult = epoll_ctl(mEpollFd, EPOLL_CTL_DEL, fd, NULL);
+ if (epollResult < 0) {
+ LOGE("Error removing epoll events for fd %d, errno=%d", fd, errno);
+ return -1;
+ }
+
+ mRequests.removeItemsAt(requestIndex);
+ } // request lock
+ return 1;
+}
+
+} // namespace android