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Use eventfd instead of pipe in Looper.

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Bug: 19933224
Change-Id: I6611e918db960bbb0e74f8308e10bdf79510b899
This commit is contained in:
Tim Kilbourn 2015-03-26 14:36:32 -07:00
parent c38eb8f390
commit 8892ce6383
2 changed files with 15 additions and 34 deletions
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3
include/utils/Looper.h
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@ -447,8 +447,7 @@ private:
const bool mAllowNonCallbacks; // immutable
int mWakeReadPipeFd; // immutable
int mWakeWritePipeFd; // immutable
int mWakeEventFd; // immutable
Mutex mLock;
Vector<MessageEnvelope> mMessageEnvelopes; // guarded by mLock

46
libutils/Looper.cpp
View file

@ -21,6 +21,7 @@
#include <fcntl.h>
#include <limits.h>
#include <inttypes.h>
#include <sys/eventfd.h>
namespace android {
@ -71,28 +72,15 @@ Looper::Looper(bool allowNonCallbacks) :
mAllowNonCallbacks(allowNonCallbacks), mSendingMessage(false),
mPolling(false), mEpollFd(-1), mEpollRebuildRequired(false),
mNextRequestSeq(0), mResponseIndex(0), mNextMessageUptime(LLONG_MAX) {
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);
mWakeEventFd = eventfd(0, EFD_NONBLOCK);
LOG_ALWAYS_FATAL_IF(mWakeEventFd < 0, "Could not make wake event fd. errno=%d", errno);
AutoMutex _l(mLock);
rebuildEpollLocked();
}
Looper::~Looper() {
close(mWakeReadPipeFd);
close(mWakeWritePipeFd);
close(mWakeEventFd);
if (mEpollFd >= 0) {
close(mEpollFd);
}
@ -165,9 +153,9 @@ void Looper::rebuildEpollLocked() {
struct epoll_event eventItem;
memset(& eventItem, 0, sizeof(epoll_event)); // zero out unused members of data field union
eventItem.events = EPOLLIN;
eventItem.data.fd = mWakeReadPipeFd;
int 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",
eventItem.data.fd = mWakeEventFd;
int result = epoll_ctl(mEpollFd, EPOLL_CTL_ADD, mWakeEventFd, & eventItem);
LOG_ALWAYS_FATAL_IF(result != 0, "Could not add wake event fd to epoll instance. errno=%d",
errno);
for (size_t i = 0; i < mRequests.size(); i++) {
@ -299,11 +287,11 @@ int Looper::pollInner(int timeoutMillis) {
for (int i = 0; i < eventCount; i++) {
int fd = eventItems[i].data.fd;
uint32_t epollEvents = eventItems[i].events;
if (fd == mWakeReadPipeFd) {
if (fd == mWakeEventFd) {
if (epollEvents & EPOLLIN) {
awoken();
} else {
ALOGW("Ignoring unexpected epoll events 0x%x on wake read pipe.", epollEvents);
ALOGW("Ignoring unexpected epoll events 0x%x on wake event fd.", epollEvents);
}
} else {
ssize_t requestIndex = mRequests.indexOfKey(fd);
@ -418,12 +406,9 @@ void Looper::wake() {
ALOGD("%p ~ wake", this);
#endif
ssize_t nWrite;
do {
nWrite = write(mWakeWritePipeFd, "W", 1);
} while (nWrite == -1 && errno == EINTR);
if (nWrite != 1) {
uint64_t inc = 1;
ssize_t nWrite = TEMP_FAILURE_RETRY(write(mWakeEventFd, &inc, sizeof(uint64_t)));
if (nWrite != sizeof(uint64_t)) {
if (errno != EAGAIN) {
ALOGW("Could not write wake signal, errno=%d", errno);
}
@ -435,11 +420,8 @@ void Looper::awoken() {
ALOGD("%p ~ awoken", this);
#endif
char buffer[16];
ssize_t nRead;
do {
nRead = read(mWakeReadPipeFd, buffer, sizeof(buffer));
} while ((nRead == -1 && errno == EINTR) || nRead == sizeof(buffer));
uint64_t counter;
TEMP_FAILURE_RETRY(read(mWakeEventFd, &counter, sizeof(uint64_t)));
}
void Looper::pushResponse(int events, const Request& request) {