深入理解Bindler

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2024年7月9日发(作者：)

while (gDefaultServiceManager == NULL) {

gDefaultServiceManager = interface_cast(

ProcessState::self()->getContextObject(NULL));

if (gDefaultServiceManager == NULL)

sleep(1);

}

}

return gDefaultServiceManager;

}

ProcessState::getContextObject()

sp ProcessState::getContextObject(const sp& caller)

{

return getStrongProxyForHandle(0);

}

ProcessState::getStrongProxyForHandle()

sp ProcessState::getStrongProxyForHandle(int32_t handle)

{

sp result;

AutoMutex _l(mLock);

handle_entry* e = lookupHandleLocked(handle);

if (e != NULL) {

// We need to create a new BpBinder if there isn't currently one, OR we

// are unable to acquire a weak reference on this current one. See comment

// in getWeakProxyForHandle() for more info about this.

IBinder* b = e->binder;

if (b == NULL || !e->refs->attemptIncWeak(this)) {

if (handle == 0) {

// Special case for

// The context manager is the only object for which we create

// a BpBinder proxy without already holding a reference.

// Perform a dummy transaction to ensure the context manager

// is registered before we create the first local reference

// to it (which will occur when creating the BpBinder).

// If a local reference is created for the BpBinder when the

// context manager is not present, the driver will fail to

// provide a reference to the context manager, but the

// driver API does not return status.

//

// Note that this is not race-free if the context manager

// dies while this code runs.

//

// TODO: add a driver API to wait for context manager, or

// stop special casing handle 0 for context manager and add

// a driver API to get a handle to the context manager with

// proper reference counting.

Parcel data;

status_t status = IPCThreadState::self()->transact(

0, IBinder::PING_TRANSACTION, data, NULL, 0);

if (status == DEAD_OBJECT)

return NULL;

}

b = new BpBinder(handle);

e->binder = b;

if (b) e->refs = b->getWeakRefs();

result = b;

} else {

#endif

}

//--[Debug][mark_chen][2014/07/11][Binder] Binder transaction bad command issue

status_t err = heck();

flags |= TF_ACCEPT_FDS;

IF_LOG_TRANSACTIONS() {

TextOutput::Bundle _b(alog);

alog << "BC_TRANSACTION thr " << (void*)pthread_self() << " / hand "

<< handle << " / code " << TypeCode(code) << ": "

<< indent << data << dedent << endl;

}

if (err == NO_ERROR) {

LOG_ONEWAY(">>>> SEND from pid %d uid %d %s", getpid(), getuid(),

(flags & TF_ONE_WAY) == 0 ? "READ REPLY" : "ONE WAY");

err = writeTransactionData(BC_TRANSACTION, flags, handle, code, data, NULL);

}

if (err != NO_ERROR) {

if (reply) reply->setError(err);

return (mLastError = err);

}

if ((flags & TF_ONE_WAY) == 0) {

#if 0

if (code == 4) { // relayout

ALOGI(">>>>>> CALLING transaction 4");

} else {

ALOGI(">>>>>> CALLING transaction %d", code);

}

#endif

if (reply) {

err = waitForResponse(reply);

} else {

Parcel fakeReply;

err = waitForResponse(&fakeReply);

}

#if 0

if (code == 4) { // relayout

ALOGI("<<<<<< RETURNING transaction 4");

} else {

ALOGI("<<<<<< RETURNING transaction %d", code);

}

#endif

IF_LOG_TRANSACTIONS() {

TextOutput::Bundle _b(alog);

alog << "BR_REPLY thr " << (void*)pthread_self() << " / hand "

<< handle << ": ";

if (reply) alog << indent << *reply << dedent << endl;

else alog << "(none requested)" << endl;

}

} else {

err = waitForResponse(NULL, NULL);

}

return err;

}

IPCThreadState::waitForResponse()

status_t IPCThreadState::waitForResponse(Parcel *reply, status_t *acquireResult)

{

uint32_t cmd;

int32_t err;

while (1) {

if ((err=talkWithDriver()) < NO_ERROR) break;

err = heck();

if (err < NO_ERROR) break;

if (ail() == 0) continue;

cmd = (uint32_t)t32();

IF_LOG_COMMANDS() {

alog << "Processing waitForResponse Command: "

<< getReturnString(cmd) << endl;

}

switch (cmd) {

case BR_TRANSACTION_COMPLETE:

if (!reply && !acquireResult) goto finish;

break;

case BR_DEAD_REPLY:

err = DEAD_OBJECT;

goto finish;

case BR_FAILED_REPLY:

err = FAILED_TRANSACTION;

goto finish;

case BR_ACQUIRE_RESULT:

{

ALOG_ASSERT(acquireResult != NULL, "Unexpected brACQUIRE_RESULT");

const int32_t result = t32();

if (!acquireResult) continue;

*acquireResult = result ? NO_ERROR : INVALID_OPERATION;

}

goto finish;

case BR_REPLY:

{

binder_transaction_data tr;

err = (&tr, sizeof(tr));

ALOG_ASSERT(err == NO_ERROR, "Not enough command data for brREPLY");

if (err != NO_ERROR) goto finish;

if (reply) {

if (( & TF_STATUS_CODE) == 0) {

reply->ipcSetDataReference(

reinterpret_cast(),

_size,

reinterpret_cast(s),

s_size/sizeof(binder_size_t),

freeBuffer, this);

} else {

err = *reinterpret_cast();

freeBuffer(NULL,

reinterpret_cast(),

_size,

reinterpret_cast(s),

s_size/sizeof(binder_size_t), this);

}

} else {

freeBuffer(NULL,

reinterpret_cast(),

_size,

reinterpret_cast(s),

s_size/sizeof(binder_size_t), this);

continue;

}

}

goto finish;

default:

err = executeCommand(cmd);

if (err != NO_ERROR) goto finish;

break;

}

}

finish:

if (err != NO_ERROR) {

if (acquireResult) *acquireResult = err;

if (reply) reply->setError(err);

mLastError = err;

}

return err;

}

MediaPlayerService服务的消息循环

void ProcessState::startThreadPool()

{

AutoMutex _l(mLock);

if (!mThreadPoolStarted) {

mThreadPoolStarted = true;

spawnPooledThread(true);

}

}

void ProcessState::spawnPooledThread(bool isMain)

{

if (mThreadPoolStarted) {

String8 name = makeBinderThreadName();

ALOGV("Spawning new pooled thread, name=%sn", ());

sp t = new PoolThread(isMain);

t->run(());

}

}

IPCThreadState::joinThreadPool()

void IPCThreadState::joinThreadPool(bool isMain)

{

LOG_THREADPOOL("**** THREAD %p (PID %d) IS JOINING THE THREAD POOLn", (void*)pthread_self(), getpid());

nt32(isMain ? BC_ENTER_LOOPER : BC_REGISTER_LOOPER);

// This thread may have been spawned by a thread that was in the background

// scheduling group, so first we will make sure it is in the foreground

// one to avoid performing an initial transaction in the background.

set_sched_policy(mMyThreadId, SP_FOREGROUND);

status_t result;

do {

//++[Debug][mark_chen][2014/07/11][Binder] Binder transaction bad command issue

mCanTransact = false;

processPendingDerefs();

mCanTransact = true;

//--[Debug][mark_chen][2014/07/11][Binder] Binder transaction bad command issue

// now get the next command to be processed, waiting if necessary

result = getAndExecuteCommand();

if (result < NO_ERROR && result != TIMED_OUT && result != -ECONNREFUSED && result != -EBADF) {

ALOGE("getAndExecuteCommand(fd=%d) returned unexpected error %d, aborting",

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