ustd/lowlevel.c

   1 #include "tracer.h"
   2 #include "ustd.h"
   3 #include "localerr.h"
   4
   5 #define USTD_BUFFER_TRUNC(offset, bufinfo) \
   6         ((offset) & (~(((bufinfo)->subbuf_size*(bufinfo)->n_subbufs)-1)))
   7
   8 void finish_consuming_dead_subbuffer(struct buffer_info *buf)
   9 {
  10         struct ltt_channel_buf_struct *ltt_buf = buf->bufstruct_mem;
  11
  12         long write_offset = local_read(&ltt_buf->offset);
  13         long consumed_offset = atomic_long_read(&ltt_buf->consumed);
  14
  15         long i_subbuf;
  16
  17         DBG("processing died buffer");
  18         DBG("consumed offset is %ld", consumed_offset);
  19         DBG("write offset is %ld", write_offset);
  20
  21         long first_subbuf = write_offset / buf->subbuf_size;
  22         long last_subbuf = consumed_offset / buf->subbuf_size;
  23
  24         if(last_subbuf - first_subbuf > buf->n_subbufs) {
  25                 DBG("an overflow has occurred, nothing can be recovered");
  26                 return;
  27         }
  28
  29         for(i_subbuf=first_subbuf; ; i_subbuf++, i_subbuf %= buf->n_subbufs) {
  30                 long commit_count = local_read(&ltt_buf->commit_count[i_subbuf]);
  31
  32                 unsigned long valid_length = buf->subbuf_size;
  33                 long n_subbufs_order = get_count_order(buf->n_subbufs);
  34                 long commit_count_mask = (~0UL >> n_subbufs_order);
  35
  36                 /* check if subbuf was fully written */
  37                 if (((commit_count - buf->subbuf_size) & commit_count_mask)
  38                     - (USTD_BUFFER_TRUNC(consumed_offset, buf) >> n_subbufs_order)
  39                     != 0) {
  40                         struct ltt_subbuffer_header *header = (struct ltt_subbuffer_header *)((char *)buf->mem)+i_subbuf*buf->subbuf_size;
  41                         valid_length = buf->subbuf_size - header->lost_size;
  42                 }
  43
  44                 patient_write(buf->file_fd, buf->mem + i_subbuf * buf->subbuf_size, buf->subbuf_size);
  45
  46                 if(i_subbuf == last_subbuf)
  47                         break;
  48         }
  49 }
  50