upipe/upipe_helper_sink.h header reference

Upipe helper functions for sinks More

• upipe/ubase.h
• upipe/ulist.h
• upipe/uref.h
• upipe/upump.h
• upipe/upump_blocker.h
• upipe/upipe.h

• UPIPE_HELPER_SINK

It allows to block a source pump, and to bufferize incoming urefs.

This macro is declared in upipe/upipe_helper_sink.h source file, line 145.

This macro declares eight functions helping a sink pipe to block source pumps, and to hold urefs that can't be immediately output.

You must add four members to your private upipe structure, for instance:

You must also declare UPIPE_HELPER_UPIPE prior to using this macro.

Supposing the name of your structure is upipe_foo, it declares:

• void upipe_foo_init_sink(struct upipe *upipe)

  Typically called in your upipe_foo_alloc() function.

• void upipe_foo_block_sink_cb(struct upump_blocker *blocker)

  Used internally as the callback of the blocker, called when the source pump is released.

• void upipe_foo_block_sink(struct upipe *upipe, struct upump **upump_p)

  Called when you need to block a source pump.

• void upipe_foo_unblock_sink(struct upipe *upipe)

  Called when you want to restart the source pump(s).

• bool upipe_foo_check_sink(struct upipe *upipe)

  Returns true if no uref has been held.

• void upipe_foo_hold_sink(struct upipe *upipe, struct uref *uref)

  Holds the given uref that can't be immediately output.

• struct uref *upipe_foo_pop_sink(struct upipe *upipe)

  Returns the first buffered uref.

• @item @code
bool upipe_foo_output_sink(struct upipe *upipe)

  Outputs urefs that have been held.

• int upipe_foo_get_max_length(struct upipe *upipe, unsigned int *p)

  Typically called from your upipe_foo_control() handler, such as:

  case UPIPE_SINK_GET_MAX_LENGTH: {
unsigned int *p = va_arg(args, unsigned int *);
return upipe_foo_get_max_length(upipe, p);
}
• int upipe_foo_set_max_length(struct upipe *upipe, unsigned int max_length)

  Typically called from your upipe_foo_control() handler, such as:

  case UPIPE_SINK_SET_MAX_LENGTH: {
unsigned int max_length = va_arg(args, unsigned int);
return upipe_foo_set_max_length(upipe, max_length);
}
• void upipe_foo_clean_sink(struct upipe *upipe)

  Free all urefs that have been held, and unblocks all pumps.

• bool upipe_foo_flush_sink(struct upipe *upipe)

  Free all urefs that have been held, unblocks all pumps, and reinitializes the sink. Returns true if the sink was previsouly blocked.

Parameters list:

• STRUCTURE: name of your private upipe structure
• UREFS: name of the struct uchain field of your private upipe structure, corresponding to a list of urefs
• BLOCKERS: name of the struct uchain field of your private upipe structure, corresponding to a list of blockers
• OUTPUT: function to use to output urefs (struct upipe *, struct uref *, struct upump **), returns false when the uref can't be written

This macro is declared in upipe/upipe_helper_sink.h source file, line 32.