drivers/staging/lttng/lib/ringbuffer/iterator.h

   1 #ifndef _LINUX_RING_BUFFER_ITERATOR_H
   2 #define _LINUX_RING_BUFFER_ITERATOR_H
   3
   4 /*
   5  * linux/ringbuffer/iterator.h
   6  *
   7  * (C) Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  *
   9  * Ring buffer and channel iterators.
  10  *
  11  * Author:
  12  *      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  13  *
  14  * Dual LGPL v2.1/GPL v2 license.
  15  */
  16
  17 #include "../../wrapper/ringbuffer/backend.h"
  18 #include "../../wrapper/ringbuffer/frontend.h"
  19
  20 /*
  21  * lib_ring_buffer_get_next_record advances the buffer read position to the next
  22  * record. It returns either the size of the next record, -EAGAIN if there is
  23  * currently no data available, or -ENODATA if no data is available and buffer
  24  * is finalized.
  25  */
  26 extern ssize_t lib_ring_buffer_get_next_record(struct channel *chan,
  27                                                struct lib_ring_buffer *buf);
  28
  29 /*
  30  * channel_get_next_record advances the buffer read position to the next record.
  31  * It returns either the size of the next record, -EAGAIN if there is currently
  32  * no data available, or -ENODATA if no data is available and buffer is
  33  * finalized.
  34  * Returns the current buffer in ret_buf.
  35  */
  36 extern ssize_t channel_get_next_record(struct channel *chan,
  37                                        struct lib_ring_buffer **ret_buf);
  38
  39 /**
  40  * read_current_record - copy the buffer current record into dest.
  41  * @buf: ring buffer
  42  * @dest: destination where the record should be copied
  43  *
  44  * dest should be large enough to contain the record. Returns the number of
  45  * bytes copied.
  46  */
  47 static inline size_t read_current_record(struct lib_ring_buffer *buf, void *dest)
  48 {
  49         return lib_ring_buffer_read(&buf->backend, buf->iter.read_offset,
  50                                     dest, buf->iter.payload_len);
  51 }
  52
  53 extern int lib_ring_buffer_iterator_open(struct lib_ring_buffer *buf);
  54 extern void lib_ring_buffer_iterator_release(struct lib_ring_buffer *buf);
  55 extern int channel_iterator_open(struct channel *chan);
  56 extern void channel_iterator_release(struct channel *chan);
  57
  58 extern const struct file_operations channel_payload_file_operations;
  59 extern const struct file_operations lib_ring_buffer_payload_file_operations;
  60
  61 /*
  62  * Used internally.
  63  */
  64 int channel_iterator_init(struct channel *chan);
  65 void channel_iterator_unregister_notifiers(struct channel *chan);
  66 void channel_iterator_free(struct channel *chan);
  67 void channel_iterator_reset(struct channel *chan);
  68 void lib_ring_buffer_iterator_reset(struct lib_ring_buffer *buf);
  69
  70 #endif /* _LINUX_RING_BUFFER_ITERATOR_H */