diff options
Diffstat (limited to 'libs/utils/Looper.cpp')
| -rw-r--r-- | libs/utils/Looper.cpp | 368 |
1 files changed, 368 insertions, 0 deletions
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 |