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binder: add polling / single-threaded operation

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This is currently safe to do only for processes that disallow any binder
threads to be created: setThreadPoolMaxThreadCount(0).

Change-Id: I8a27f3cf26f4d51edb7f222af487ac256cbcab65
This commit is contained in:
Todd Poynor 2013-06-25 19:12:18 -07:00
parent 3e5fa73722
commit 8d96cab8bf
2 changed files with 92 additions and 51 deletions
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4
include/binder/IPCThreadState.h
View File

@ -51,6 +51,8 @@ public:
int64_t clearCallingIdentity();
void restoreCallingIdentity(int64_t token);
int setupPolling(int* fd);
status_t handlePolledCommands();
void flushCommands();
void joinThreadPool(bool isMain = true);
@ -96,7 +98,9 @@ private:
uint32_t code,
const Parcel& data,
status_t* statusBuffer);
status_t getAndExecuteCommand();
status_t executeCommand(int32_t command);
void processPendingDerefs();
void clearCaller();

139
libs/binder/IPCThreadState.cpp
View File

@ -418,6 +418,60 @@ void IPCThreadState::flushCommands()
talkWithDriver(false);
}
status_t IPCThreadState::getAndExecuteCommand()
{
status_t result;
int32_t cmd;
result = talkWithDriver();
if (result >= NO_ERROR) {
size_t IN = mIn.dataAvail();
if (IN < sizeof(int32_t)) return result;
cmd = mIn.readInt32();
IF_LOG_COMMANDS() {
alog << "Processing top-level Command: "
<< getReturnString(cmd) << endl;
}
result = executeCommand(cmd);
// After executing the command, ensure that the thread is returned to the
// foreground cgroup before rejoining the pool. The driver takes care of
// restoring the priority, but doesn't do anything with cgroups so we
// need to take care of that here in userspace. Note that we do make
// sure to go in the foreground after executing a transaction, but
// there are other callbacks into user code that could have changed
// our group so we want to make absolutely sure it is put back.
set_sched_policy(mMyThreadId, SP_FOREGROUND);
}
return result;
}
// When we've cleared the incoming command queue, process any pending derefs
void IPCThreadState::processPendingDerefs()
{
if (mIn.dataPosition() >= mIn.dataSize()) {
size_t numPending = mPendingWeakDerefs.size();
if (numPending > 0) {
for (size_t i = 0; i < numPending; i++) {
RefBase::weakref_type* refs = mPendingWeakDerefs[i];
refs->decWeak(mProcess.get());
}
mPendingWeakDerefs.clear();
}
numPending = mPendingStrongDerefs.size();
if (numPending > 0) {
for (size_t i = 0; i < numPending; i++) {
BBinder* obj = mPendingStrongDerefs[i];
obj->decStrong(mProcess.get());
}
mPendingStrongDerefs.clear();
}
}
}
void IPCThreadState::joinThreadPool(bool isMain)
{
LOG_THREADPOOL("**** THREAD %p (PID %d) IS JOINING THE THREAD POOL\n", (void*)pthread_self(), getpid());
@ -431,57 +485,16 @@ void IPCThreadState::joinThreadPool(bool isMain)
status_t result;
do {
int32_t cmd;
// When we've cleared the incoming command queue, process any pending derefs
if (mIn.dataPosition() >= mIn.dataSize()) {
size_t numPending = mPendingWeakDerefs.size();
if (numPending > 0) {
for (size_t i = 0; i < numPending; i++) {
RefBase::weakref_type* refs = mPendingWeakDerefs[i];
refs->decWeak(mProcess.get());
}
mPendingWeakDerefs.clear();
}
numPending = mPendingStrongDerefs.size();
if (numPending > 0) {
for (size_t i = 0; i < numPending; i++) {
BBinder* obj = mPendingStrongDerefs[i];
obj->decStrong(mProcess.get());
}
mPendingStrongDerefs.clear();
}
}
processPendingDerefs();
// now get the next command to be processed, waiting if necessary
result = talkWithDriver();
if (result >= NO_ERROR) {
size_t IN = mIn.dataAvail();
if (IN < sizeof(int32_t)) continue;
cmd = mIn.readInt32();
IF_LOG_COMMANDS() {
alog << "Processing top-level Command: "
<< getReturnString(cmd) << endl;
}
result = getAndExecuteCommand();
result = executeCommand(cmd);
} else if (result != TIMED_OUT && result != -ECONNREFUSED && result != -EBADF) {
ALOGE("talkWithDriver(fd=%d) returned unexpected error %d, aborting",
if (result < NO_ERROR && result != TIMED_OUT && result != -ECONNREFUSED && result != -EBADF) {
ALOGE("getAndExecuteCommand(fd=%d) returned unexpected error %d, aborting",
mProcess->mDriverFD, result);
abort();
}
// After executing the command, ensure that the thread is returned to the
// foreground cgroup before rejoining the pool. The driver takes care of
// restoring the priority, but doesn't do anything with cgroups so we
// need to take care of that here in userspace. Note that we do make
// sure to go in the foreground after executing a transaction, but
// there are other callbacks into user code that could have changed
// our group so we want to make absolutely sure it is put back.
set_sched_policy(mMyThreadId, SP_FOREGROUND);
// Let this thread exit the thread pool if it is no longer
// needed and it is not the main process thread.
if(result == TIMED_OUT && !isMain) {
@ -496,6 +509,30 @@ void IPCThreadState::joinThreadPool(bool isMain)
talkWithDriver(false);
}
int IPCThreadState::setupPolling(int* fd)
{
if (mProcess->mDriverFD <= 0) {
return -EBADF;
}
mOut.writeInt32(BC_ENTER_LOOPER);
*fd = mProcess->mDriverFD;
return 0;
}
status_t IPCThreadState::handlePolledCommands()
{
status_t result;
do {
result = getAndExecuteCommand();
} while (mIn.dataPosition() < mIn.dataSize());
processPendingDerefs();
flushCommands();
return result;
}
void IPCThreadState::stopProcess(bool immediate)
{
//ALOGI("**** STOPPING PROCESS");
@ -826,7 +863,7 @@ status_t IPCThreadState::talkWithDriver(bool doReceive)
IF_LOG_COMMANDS() {
alog << "Our err: " << (void*)err << ", write consumed: "
<< bwr.write_consumed << " (of " << mOut.dataSize()
<< "), read consumed: " << bwr.read_consumed << endl;
<< "), read consumed: " << bwr.read_consumed << endl;
}
if (err >= NO_ERROR) {
@ -1104,16 +1141,16 @@ status_t IPCThreadState::executeCommand(int32_t cmd)
void IPCThreadState::threadDestructor(void *st)
{
IPCThreadState* const self = static_cast<IPCThreadState*>(st);
if (self) {
self->flushCommands();
IPCThreadState* const self = static_cast<IPCThreadState*>(st);
if (self) {
self->flushCommands();
#if defined(HAVE_ANDROID_OS)
if (self->mProcess->mDriverFD > 0) {
ioctl(self->mProcess->mDriverFD, BINDER_THREAD_EXIT, 0);
}
#endif
delete self;
}
delete self;
}
}