Skip to content

Commit

Permalink
more thread safety
Browse files Browse the repository at this point in the history 
- added mutex to restrict libv4l calls to one at a time per file descriptor
- had to remove a lot of consts from function due to mutex usage
  • Loading branch information
@hydroo
hydroo committed Aug 21, 2009
1 parent 43eef87 commit 533146a
Show file tree
Hide file tree
Showing 2 changed files with 51 additions and 31 deletions.
64 changes: 40 additions & 24 deletions src/CaptureDevice.cpp
View file
Expand Up @@ -19,7 +19,6 @@
using namespace std;


static int xioctl(int fileDescriptor, int request, void *arg);


CaptureDevice::CaptureDevice() :
Expand Down Expand Up @@ -124,7 +123,9 @@ bool CaptureDevice::init(const string& deviceFileName, __u32 pixelFormat, unsign
finish(); return false;
}

m_libv4lAccessMutex.lock();
m_fileDescriptor = v4l2_open(m_deviceFileName.c_str(), O_RDWR|O_NONBLOCK);
m_libv4lAccessMutex.unlock();

if (m_fileDescriptor == -1) {
cerr << "Cannot open file. " << errno << strerror (errno) << endl;
Expand All @@ -135,7 +136,7 @@ bool CaptureDevice::init(const string& deviceFileName, __u32 pixelFormat, unsign
/* *** initialize capturing *** */
struct v4l2_capability cap;

if (xioctl(m_fileDescriptor, VIDIOC_QUERYCAP, &cap) == -1) {
if (xv4l2_ioctl(m_fileDescriptor, VIDIOC_QUERYCAP, &cap) == -1) {
if (EINVAL == errno) {
cerr << "File is no V4L2 device." << endl;
finish(); return false;
Expand All @@ -161,11 +162,11 @@ bool CaptureDevice::init(const string& deviceFileName, __u32 pixelFormat, unsign
memset(&cropcap, 0, sizeof(v4l2_cropcap));

cropcap.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
xioctl(m_fileDescriptor, VIDIOC_CROPCAP, &cropcap); /* ignore errors */
xv4l2_ioctl(m_fileDescriptor, VIDIOC_CROPCAP, &cropcap); /* ignore errors */

crop.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
crop.c = cropcap.defrect;
xioctl(m_fileDescriptor, VIDIOC_S_CROP, &crop); /* ignore errors */
xv4l2_ioctl(m_fileDescriptor, VIDIOC_S_CROP, &crop); /* ignore errors */


struct v4l2_format fmt;
Expand All @@ -177,7 +178,7 @@ bool CaptureDevice::init(const string& deviceFileName, __u32 pixelFormat, unsign
fmt.fmt.pix.pixelformat = m_pixelFormat;
fmt.fmt.pix.field = m_fieldFormat;

if (xioctl(m_fileDescriptor, VIDIOC_S_FMT, &fmt) == -1) {
if (xv4l2_ioctl(m_fileDescriptor, VIDIOC_S_FMT, &fmt) == -1) {
cerr << __PRETTY_FUNCTION__ << " VIDIOC_S_FMT " << errno << strerror(errno) << endl;
finish(); return false;
}
Expand Down Expand Up @@ -237,7 +238,10 @@ void CaptureDevice::finish()

/* *** close device *** */
if (m_fileDescriptor != -1) {
if (v4l2_close(m_fileDescriptor) == -1) {
m_libv4lAccessMutex.lock();
int ret = v4l2_close(m_fileDescriptor);
m_libv4lAccessMutex.unlock();
if (ret == -1) {
cerr << __PRETTY_FUNCTION__ << "Could not close device file. " << errno << " " << strerror(errno) << endl;
}
m_fileDescriptor = -1;
Expand All @@ -256,14 +260,14 @@ void CaptureDevice::finish()
}


void CaptureDevice::printDeviceInfo() const
void CaptureDevice::printDeviceInfo()
{
// cerr << __PRETTY_FUNCTION__ << endl;
assert(m_fileDescriptor != -1);

struct v4l2_capability cap;
/* check capabilities */
if (xioctl(m_fileDescriptor, VIDIOC_QUERYCAP, &cap) == -1) {
if (xv4l2_ioctl(m_fileDescriptor, VIDIOC_QUERYCAP, &cap) == -1) {
if (EINVAL == errno) {
cerr << "Device is no V4L2 device." << endl;
assert(0);
Expand Down Expand Up @@ -292,7 +296,7 @@ void CaptureDevice::printDeviceInfo() const
}


void CaptureDevice::printControls() const
void CaptureDevice::printControls()
{
// cerr << __PRETTY_FUNCTION__ << endl;
assert(m_fileDescriptor != -1);
Expand Down Expand Up @@ -352,7 +356,7 @@ void CaptureDevice::printControls() const
}


void CaptureDevice::printFormats() const
void CaptureDevice::printFormats()
{
// cerr << __PRETTY_FUNCTION__ << endl;
assert(m_fileDescriptor != -1);
Expand Down Expand Up @@ -434,7 +438,7 @@ void CaptureDevice::printFormats() const
format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
format.index = formatIndex;

ioctlError = ioctl (m_fileDescriptor, VIDIOC_ENUM_FMT, &format);
ioctlError = xv4l2_ioctl (m_fileDescriptor, VIDIOC_ENUM_FMT, &format);

if (ioctlError == 0) {
for (int a = 0; a < formatCount; ++a) {
Expand Down Expand Up @@ -562,7 +566,7 @@ void CaptureDevice::stopCapturing()
}


pair<list<struct v4l2_queryctrl>, list<struct v4l2_querymenu> > CaptureDevice::controls() const
pair<list<struct v4l2_queryctrl>, list<struct v4l2_querymenu> > CaptureDevice::controls()
{
pair<list<struct v4l2_queryctrl>, list<struct v4l2_querymenu> > ret;

Expand Down Expand Up @@ -599,12 +603,12 @@ pair<list<struct v4l2_queryctrl>, list<struct v4l2_querymenu> > CaptureDevice::c
}


bool CaptureDevice::control(struct v4l2_control& ctl) const
bool CaptureDevice::control(struct v4l2_control& ctl)
{
/* which errors VIDIOC_G_CTRL can throw:
http://www.linuxtv.org/downloads/video4linux/API/V4L2_API/spec-single/v4l2.html#VIDIOC-G-CTRL */

if (xioctl(m_fileDescriptor, VIDIOC_G_CTRL, &ctl) == 0) {
if (xv4l2_ioctl(m_fileDescriptor, VIDIOC_G_CTRL, &ctl) == 0) {

/* v4l-copied: The driver may clamp the value or return ERANGE, ignored here */

Expand All @@ -623,7 +627,7 @@ bool CaptureDevice::setControl(const struct v4l2_control& ctl)
/* which errors VIDIOC_S_CTRL can throw:
http://www.linuxtv.org/downloads/video4linux/API/V4L2_API/spec-single/v4l2.html#VIDIOC-G-CTRL */

if (xioctl(m_fileDescriptor, VIDIOC_S_CTRL, &copiedCtl) == 0) {
if (xv4l2_ioctl(m_fileDescriptor, VIDIOC_S_CTRL, &copiedCtl) == 0) {
return true;
} else {
cerr << __PRETTY_FUNCTION__ << " VIDIOC_S_CTRL " << errno << strerror(errno) << endl;
Expand All @@ -632,7 +636,7 @@ bool CaptureDevice::setControl(const struct v4l2_control& ctl)
}


bool CaptureDevice::queryControl(struct v4l2_queryctrl& ctl) const
bool CaptureDevice::queryControl(struct v4l2_queryctrl& ctl)
{
bool ret = false;

Expand All @@ -641,7 +645,7 @@ bool CaptureDevice::queryControl(struct v4l2_queryctrl& ctl) const
memset (&ctl, 0, sizeof(v4l2_queryctrl));
ctl.id = id;

if (xioctl(m_fileDescriptor, VIDIOC_QUERYCTRL, &ctl) == 0) {
if (xv4l2_ioctl(m_fileDescriptor, VIDIOC_QUERYCTRL, &ctl) == 0) {
ret = true;
} else if (errno == EINVAL) {
/* invalid ids are anticipated */
Expand All @@ -655,7 +659,7 @@ bool CaptureDevice::queryControl(struct v4l2_queryctrl& ctl) const
}


list<v4l2_querymenu> CaptureDevice::menus(const struct v4l2_queryctrl& ctl) const
list<v4l2_querymenu> CaptureDevice::menus(const struct v4l2_queryctrl& ctl)
{
list<struct v4l2_querymenu> ret;

Expand All @@ -665,7 +669,7 @@ list<v4l2_querymenu> CaptureDevice::menus(const struct v4l2_queryctrl& ctl) cons

for (menu.index = ctl.minimum; ((__s32) menu.index) <= ctl.maximum; menu.index++) {

if (xioctl(m_fileDescriptor, VIDIOC_QUERYMENU, &menu) == 0) {
if (xv4l2_ioctl(m_fileDescriptor, VIDIOC_QUERYMENU, &menu) == 0) {
ret.push_back(menu);
} else {
/* this is no crucial error - just a suposed menu index, who is not anyways */
Expand All @@ -685,6 +689,7 @@ void CaptureDevice::determineCapturePeriodThread(double secondsToIterate,
unsigned int bufferSize = camera->m_bufferSize;
clockid_t clockId = camera->m_timerClockId;
void *buffer = malloc(camera->m_bufferSize);
std::mutex& libv4lAccessMutex = camera->m_libv4lAccessMutex;
fd_set filedescriptorset;
struct timeval tv;
int sel;
Expand Down Expand Up @@ -717,7 +722,9 @@ void CaptureDevice::determineCapturePeriodThread(double secondsToIterate,
}

/* read from the device */
libv4lAccessMutex.lock();
readlen = v4l2_read(fileDescriptor, buffer, bufferSize);
libv4lAccessMutex.unlock();

if (readlen == -1) {
cerr << __PRETTY_FUNCTION__ << " Read error. " << errno << strerror(errno) << endl;
Expand Down Expand Up @@ -762,6 +769,7 @@ void CaptureDevice::captureThread(CaptureDevice* camera)
clockid_t clockId = camera->m_timerClockId;
std::deque<Buffer*>& sortedBuffers = camera->m_timelySortedBuffers;
std::mutex& sortedBuffersMutex = camera->m_timelySortedBuffersMutex;
std::mutex& libv4lAccessMutex = camera->m_libv4lAccessMutex;
fd_set filedescriptorset;
struct timeval tv;
int sel;
Expand All @@ -772,18 +780,20 @@ void CaptureDevice::captureThread(CaptureDevice* camera)

FD_ZERO(&filedescriptorset);
FD_SET(fileDescriptor, &filedescriptorset);
tv.tv_sec = 2;
tv.tv_sec = 1;
tv.tv_usec = 0;

/* watch the file handle for new readable data */
libv4lAccessMutex.lock();
sel = select(fileDescriptor + 1, &filedescriptorset, NULL, NULL, &tv);
libv4lAccessMutex.unlock();

if (sel == -1 && errno != EINTR) {
cerr << __PRETTY_FUNCTION__ << " Select error. " << errno << strerror(errno) << endl;
abort();
} else if (sel == 0) {
cerr << __PRETTY_FUNCTION__ << " Select timeout. " << errno << strerror(errno) << endl;
assert(0);
} else if (sel == 0) {
/* select timeout */
continue;
}

/* remove the last element if possible */
Expand All @@ -801,7 +811,9 @@ void CaptureDevice::captureThread(CaptureDevice* camera)

/* read from the device into the buffer */
clock_gettime(clockId, &(buffer->time));
libv4lAccessMutex.lock();
readlen = v4l2_read(fileDescriptor, buffer->buffer, bufferSize);
libv4lAccessMutex.unlock();

if (readlen == -1) {
cerr << __PRETTY_FUNCTION__ << " Read error. " << errno << strerror(errno) << endl;
Expand All @@ -824,12 +836,16 @@ void CaptureDevice::captureThread(CaptureDevice* camera)


/** helper, which calls ioctl until an undisturbed call has been done */
int xioctl(int fileDescriptor, int request, void *arg)
int CaptureDevice::xv4l2_ioctl(int fileDescriptor, int request, void *arg)
{
int r;

m_libv4lAccessMutex.lock();

do r = v4l2_ioctl (fileDescriptor, request, arg);
while (-1 == r && EINTR == errno);

m_libv4lAccessMutex.unlock();

return r;
}
Expand Down
18 changes: 11 additions & 7 deletions src/CaptureDevice.hpp
View file
Expand Up @@ -68,9 +68,9 @@ class CaptureDevice

void finish();

void printDeviceInfo() const;
void printControls() const;
void printFormats() const;
void printDeviceInfo();
void printControls();
void printFormats();
void printTimerInformation() const;

struct Buffer
Expand Down Expand Up @@ -103,23 +103,25 @@ class CaptureDevice

/** @see http://www.linuxtv.org/downloads/video4linux/API/V4L2_API/spec-single/v4l2.html#V4L2-QUERYCTRL
@see http://www.linuxtv.org/downloads/video4linux/API/V4L2_API/spec-single/v4l2.html#V4L2-QUERYMENU */
std::pair<std::list<struct v4l2_queryctrl>, std::list<struct v4l2_querymenu> > controls() const;
std::pair<std::list<struct v4l2_queryctrl>, std::list<struct v4l2_querymenu> > controls();

/** @see http://www.linuxtv.org/downloads/video4linux/API/V4L2_API/spec-single/v4l2.html#V4L2-CONTROL
@returns whether the result is valid - why? -> better error checking to come */
bool control(struct v4l2_control&) const;
bool control(struct v4l2_control&);
/** @returns whether the call succeeded - why not ? -> better error checking to come */
bool setControl(const struct v4l2_control&);

private:

bool queryControl(struct v4l2_queryctrl&) const;
std::list<struct v4l2_querymenu> menus(const struct v4l2_queryctrl&) const;
bool queryControl(struct v4l2_queryctrl&);
std::list<struct v4l2_querymenu> menus(const struct v4l2_queryctrl&);

static void captureThread(CaptureDevice* camera);
static void determineCapturePeriodThread(double, CaptureDevice*,
std::pair<double,double>*);

int xv4l2_ioctl(int fileDescriptor, int request, void *arg);

unsigned int m_captureHeight;
unsigned int m_captureWidth;
int m_fileDescriptor;
Expand All @@ -140,6 +142,8 @@ class CaptureDevice

std::thread *m_captureThread;
bool m_captureThreadCancellationFlag;

std::mutex m_libv4lAccessMutex;
};


Expand Down

0 comments on commit 533146a

Please sign in to comment.