Fix memory leak and other minor pthread usage issues in FIFOWriter

[anonymous]

This patch addresses a few issues that I noticed while browsing through libs/libmythtv/fifowriter.cpp:

• The array of locks, fifo_lock, was not deleted in the FIFOWriter destructor.
• pthread_mutex_init() was not called on the array of locks in the FIFOWriter constructor. This is usually not that big of a deal on Linux because the default initial value of pthread_mutex_t is zeroed out. However, it can lead to weird problems on other platforms.
• pthread_mutex_destroy() and pthread_cond_destroy() were not called on the two arrays of thread conditions and the one array of locks in the FIFOWriter destructor. This can potentially create memory leaks.
• There are two places where the empty_cond condition is signaled without locking the appropriate mutex.

IRC: russellb

[Stuart Auchterlonie]

Initial testing of this and i've not managed to lockup my frontend by causing it to generate too many previews.

Would other people with issues with the preview thread please test this and report back.

Stuart

[russell@…]

I have attached a second patch: fifowriter.rev2.patch, which addresses the original concerns as well as the following:

• Converts the locks and thread conditions in FIFOWriter from using the pthread API directly, to using QMutex and QWaitCondition.
• Converts the locks and thread conditions in HDTVRecorder to the same.

[russell@…]

Note that my point about pthread_mutex_init() not getting called in FIFOWriter wasn't actually correct. However, the rest is still true. :)

[anonymous]

Even though stuarta said I didn't have to, I posted another patch that *only* contains the bug fixes, and no "code cleanup" changes. I will submit those changes separately. Also, the patch was created from the root of the project instead of a subdirectory.

[Stuart Auchterlonie]

(In [13443]) Closes #3381. Applies patch from russellb that cleans up the lock handling and thread usage in fifowriter.

Been running this for a while and it makes things more stable.