avcodec/pthread_frame: Move (init|free)_pthread() to pthread.c

We have more mutexes/condition variables whose initialization is
unchecked.
Also use a proper namespace for these functions.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

1 files changed, 32 insertions, 0 deletions

diff --git a/libavcodec/pthread_internal.h b/libavcodec/pthread_internal.h
index d2115cbbaf..d0b6a7a673 100644
--- a/libavcodec/pthread_internal.h
+++ b/libavcodec/pthread_internal.h
@@ -31,4 +31,36 @@ void ff_slice_thread_free(AVCodecContext *avctx);
 int ff_frame_thread_init(AVCodecContext *avctx);
 void ff_frame_thread_free(AVCodecContext *avctx, int thread_count);
 
+#define THREAD_SENTINEL 0 // This forbids putting a mutex/condition variable at the front.
+/**
+ * Initialize/destroy a list of mutexes/conditions contained in a structure.
+ * The positions of these mutexes/conditions in the structure are given by
+ * their offsets. Because it is undefined behaviour to destroy
+ * an uninitialized mutex/condition, ff_pthread_init() stores the number
+ * of successfully initialized mutexes and conditions in the object itself
+ * and ff_pthread_free() uses this number to destroy exactly the mutexes and
+ * condition variables that have been successfully initialized.
+ *
+ * @param     obj     The object containing the mutexes/conditions.
+ * @param[in] offsets An array of offsets. Its first member gives the offset
+ *                    of the variable that contains the count of successfully
+ *                    initialized mutexes/condition variables; said variable
+ *                    must be an unsigned int. Two arrays of offsets, each
+ *                    delimited by a THREAD_SENTINEL follow. The first
+ *                    contains the offsets of all the mutexes, the second
+ *                    contains the offsets of all the condition variables.
+ */
+int  ff_pthread_init(void *obj, const unsigned offsets[]);
+void ff_pthread_free(void *obj, const unsigned offsets[]);
+
+/**
+ * Macros to help creating the above lists. mutexes and conds need
+ * to be parentheses-enclosed lists of offsets in the containing structure.
+ */
+#define OFFSET_ARRAY(...) __VA_ARGS__, THREAD_SENTINEL
+#define DEFINE_OFFSET_ARRAY(type, name, cnt_variable, mutexes, conds)         \
+static const unsigned name ## _offsets[] = { offsetof(type, cnt_variable),    \
+                                             OFFSET_ARRAY mutexes,            \
+                                             OFFSET_ARRAY conds }
+
 #endif // AVCODEC_PTHREAD_INTERNAL_H