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zeroconf: clean up destruction/startup

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* fixed race condition in destruction (hopefully ;)
* cleaned startup status testing in MainConnection
* faster shutdown/startup, less blocking in embedded lib getProperty

Change-Id: I3e9062fa59465523feb47ba195cf4ef465d2c16c
Reviewed-by: Daniel Molkentin <daniel.molkentin@nokia.com>
This commit is contained in:
Fawzi Mohamed
2012-03-28 18:04:13 +02:00
parent 65c1be9bc8
commit 12236050b9
3 changed files with 78 additions and 55 deletions
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21
src/libs/zeroconf/embed/dnssd_clientstub.c
View File

@@ -215,10 +215,29 @@ static int read_all(dnssd_sock_t sd, char *buf, int len)
{
// Don't use "MSG_WAITALL"; it returns "Invalid argument" on some Linux versions; use an explicit while () loop instead.
//if (recv(sd, buf, len, MSG_WAITALL) != len) return -1;
int nErr = 0;
while (len)
{
ssize_t num_read = recv(sd, buf, len, 0);
timeval timeout;
timeout.tv_sec = 0;
timeout.tv_usec = 100000;
fd_set readFds, writeFds, exceptFds;
memset(&readFds,0,sizeof(readFds));
memset(&writeFds,0,sizeof(writeFds));
memset(&exceptFds,0,sizeof(exceptFds));
FD_SET(sd, &readFds);
FD_SET(sd, &writeFds);
FD_SET(sd, &exceptFds);
ssize_t num_read = 0;
int nVal=select(sd+1, &readFds, &writeFds, &exceptFds, &timeout);
if (nVal < 1 || !FD_ISSET(sd, &readFds)) {
++nErr;
if (nErr < 5) // wait max 0.5s without reading
continue;
} else {
num_read = recv(sd, buf, len, 0);
}
// It is valid to get an interrupted system call error e.g., somebody attaching
// in a debugger, retry without failing
if ((num_read < 0) && (errno == EINTR)) { syslog(LOG_INFO, "dnssd_clientstub read_all: EINTR continue"); continue; }

111
src/libs/zeroconf/servicebrowser.cpp
View File

@@ -752,13 +752,17 @@ void ServiceGatherer::stopResolve(ZK_IP_Protocol protocol)
{
if ((protocol == ZK_PROTO_IPv4_OR_IPv6 || protocol == ZK_PROTO_IPv4)
&& (status & ResolveConnectionActive) != 0) {
lib()->refDeallocate(resolveConnection);
QMutexLocker l(serviceBrowser->mainConnection->lock());
if (serviceBrowser->mainConnection->status() < MainConnection::Stopping)
lib()->refDeallocate(resolveConnection);
status &= ~ResolveConnectionActive;
serviceBrowser->updateFlowStatusForCancel();
}
if ((protocol == ZK_PROTO_IPv4_OR_IPv6 || protocol == ZK_PROTO_IPv6)
&& (status & ResolveConnectionV6Active) != 0) {
lib()->refDeallocate(resolveConnectionV6);
QMutexLocker l(serviceBrowser->mainConnection->lock());
if (serviceBrowser->mainConnection->status() < MainConnection::Stopping)
lib()->refDeallocate(resolveConnectionV6);
status &= ~ResolveConnectionV6Active;
serviceBrowser->updateFlowStatusForCancel();
}
@@ -837,7 +841,9 @@ void ServiceGatherer::restartResolve(ZK_IP_Protocol protocol)
void ServiceGatherer::stopTxt()
{
if ((status & TxtConnectionActive) == 0) return;
lib()->refDeallocate(txtConnection);
QMutexLocker l(serviceBrowser->mainConnection->lock());
if (serviceBrowser->mainConnection->status() < MainConnection::Stopping)
lib()->refDeallocate(txtConnection);
status &= ~TxtConnectionActive;
serviceBrowser->updateFlowStatusForCancel();
}
@@ -863,7 +869,9 @@ void ServiceGatherer::restartTxt()
void ServiceGatherer::stopHostResolution()
{
if ((status & AddrConnectionActive) == 0) return;
lib()->refDeallocate(addrConnection);
QMutexLocker l(serviceBrowser->mainConnection->lock());
if (serviceBrowser->mainConnection->status() < MainConnection::Stopping)
lib()->refDeallocate(addrConnection);
status &= ~AddrConnectionActive;
serviceBrowser->updateFlowStatusForCancel();
}
@@ -1552,14 +1560,21 @@ void ServiceBrowserPrivate::startedBrowsing()
void MainConnection::stop(bool wait)
{
#if QT_VERSION >= 0x050000
if (m_status.load() < Stopping)
#else
if (m_status < Stopping)
#endif
{
if (QThread::currentThread() == m_thread)
qCritical() << "ERROR ZerocConf::MainConnection::stop called from m_thread";
// This will most likely lock if called from the connection thread (as mainThreadLock is non recusive)
// Making it recursive would open a hole during the startup of the thread.
// As of now this should always be called during the destruction of a browser,
// so from another thread.
increaseStatusTo(Stopping);
if (m_mainRef)
QMutexLocker l(mainThreadLock());
QMutexLocker l2(lock());
}
if (m_mainRef) {
lib->stopConnection(m_mainRef);
m_mainRef = 0;
}
if (!m_thread)
increaseStatusTo(Stopped);
else if (wait && QThread::currentThread() != m_thread)
@@ -1569,38 +1584,30 @@ void MainConnection::stop(bool wait)
MainConnection::MainConnection():
flowStatus(NormalRFS),
lib(zeroConfLibInstance()->defaultLib()), m_lock(QMutex::Recursive),
m_mainThreadLock(QMutex::Recursive), m_mainRef(0), m_failed(false), m_status(Starting), m_nErrs(0)
m_mainThreadLock(QMutex::NonRecursive), m_mainRef(0), m_failed(false), m_status(Starting), m_nErrs(0)
{
if (lib.isNull()){
qDebug() << "could not load a valid library for ZeroConf::MainConnection, failing";
} else {
m_thread = new ConnectionThread(*this);
m_mainThreadLock.lock();
m_thread->start(); // delay startup??
}
}
MainConnection::~MainConnection()
{
stop();
stop(true);
delete m_thread;
// to do
}
bool MainConnection::increaseStatusTo(int s)
{
#if QT_VERSION >= 0x050000
int sAtt = m_status.load();
#else
int sAtt = m_status;
#endif
int sAtt = status();
while (sAtt < s){
if (m_status.testAndSetRelaxed(sAtt, s))
return true;
#if QT_VERSION >= 0x050000
sAtt = m_status.load();
#else
sAtt = m_status;
#endif
sAtt = status();
}
return false;
}
@@ -1621,11 +1628,7 @@ void MainConnection::waitStartup()
while (true){
{
QMutexLocker l(lock());
#if QT_VERSION >= 0x050000
sAtt = m_status.load();
#else
sAtt = m_status;
#endif
sAtt = status();
if (sAtt >= Running)
return;
}
@@ -1639,11 +1642,7 @@ void MainConnection::addBrowser(ServiceBrowserPrivate *browser)
QList<ErrorMessage> errs;
{
QMutexLocker l(lock());
#if QT_VERSION >= 0x050000
actualStatus = m_status.load();
#else
actualStatus = m_status;
#endif
actualStatus = status();
m_browsers.append(browser);
errs = m_errors;
}
@@ -1716,11 +1715,7 @@ void MainConnection::abortLib(){
void MainConnection::createConnection()
{
gotoValidLib();
#if QT_VERSION >= 0x050000
while (m_status.load() <= Running) {
#else
while (m_status <= Running) {
#endif
while (status() <= Running) {
if (!lib) {
increaseStatusTo(Stopped);
break;
@@ -1812,19 +1807,21 @@ void MainConnection::destroyConnection()
void MainConnection::handleEvents()
{
if (!m_status.testAndSetAcquire(Starting, Started)){
appendError(ErrorMessage::WarningLevel, tr("MainConnection::handleEvents called with m_status != Starting, aborting"));
increaseStatusTo(Stopped);
return;
try {
if (!m_status.testAndSetAcquire(Starting, Started)){
appendError(ErrorMessage::WarningLevel, tr("MainConnection::handleEvents called with m_status != Starting, aborting"));
increaseStatusTo(Stopped);
return;
}
m_nErrs = 0;
createConnection();
} catch(...) {
mainThreadLock()->unlock();
throw;
}
m_nErrs = 0;
createConnection();
mainThreadLock()->unlock();
increaseStatusTo(Running);
#if QT_VERSION >= 0x050000
while (m_status.load() < Stopping) {
#else
while (m_status < Stopping) {
#endif
while (status() < Stopping) {
QMutexLocker l(mainThreadLock());
if (m_nErrs > 10)
increaseStatusTo(Stopping);
@@ -1861,16 +1858,22 @@ void MainConnection::handleEvents()
ZConfLib::ConnectionRef MainConnection::mainRef()
{
#if QT_VERSION >= 0x050000
while (m_status.load() < Running){
#else
while (m_status < Running){
#endif
while (status() < Running){
QThread::yieldCurrentThread();
}
return m_mainRef;
}
MainConnection::Status MainConnection::status()
{
#if QT_VERSION >= 0x050000
return static_cast<MainConnection::Status>(m_status.load());
#else
int val = m_status;
return static_cast<MainConnection::Status>(val);
#endif
}
QList<ErrorMessage> MainConnection::errors()
{
QMutexLocker l(lock());

1
src/libs/zeroconf/servicebrowser_p.h
View File

@@ -253,6 +253,7 @@ public:
bool increaseStatusTo(int s);
void handleEvents();
ZConfLib::ConnectionRef mainRef();
Status status();
QList<ErrorMessage> errors();
bool isOk();