ustd/lowlevel.c

   1 #include <assert.h>
   2
   3 #include "tracer.h"
   4 #include "ustd.h"
   5 #include "localerr.h"
   6
   7 #define USTD_BUFFER_TRUNC(offset, bufinfo) \
   8         ((offset) & (~(((bufinfo)->subbuf_size*(bufinfo)->n_subbufs)-1)))
   9
  10 void finish_consuming_dead_subbuffer(struct buffer_info *buf)
  11 {
  12         struct ltt_channel_buf_struct *ltt_buf = buf->bufstruct_mem;
  13
  14         long write_offset = local_read(&ltt_buf->offset);
  15         long consumed_offset = atomic_long_read(&ltt_buf->consumed);
  16
  17         long i_subbuf;
  18
  19         DBG("processing died buffer");
  20         DBG("consumed offset is %ld", consumed_offset);
  21         DBG("write offset is %ld", write_offset);
  22
  23         long first_subbuf = consumed_offset / buf->subbuf_size;
  24         long last_subbuf = write_offset / buf->subbuf_size;
  25
  26         if(last_subbuf - first_subbuf > buf->n_subbufs) {
  27                 DBG("an overflow has occurred, nothing can be recovered");
  28                 return;
  29         }
  30
  31         for(i_subbuf=first_subbuf; ; i_subbuf++, i_subbuf %= buf->n_subbufs) {
  32                 void *tmp;
  33                 long commit_seq = local_read(&ltt_buf->commit_seq[i_subbuf]);
  34
  35                 unsigned long valid_length = buf->subbuf_size;
  36                 long n_subbufs_order = get_count_order(buf->n_subbufs);
  37                 long commit_seq_mask = (~0UL >> n_subbufs_order);
  38
  39                 if((commit_seq & commit_seq_mask) == 0)
  40                         break;
  41
  42                 /* check if subbuf was fully written */
  43                 if (!((commit_seq - buf->subbuf_size) & commit_seq_mask)
  44                     - (USTD_BUFFER_TRUNC(consumed_offset, buf) >> n_subbufs_order)
  45                     != 0) {
  46                         struct ltt_subbuffer_header *header = (struct ltt_subbuffer_header *)((char *)buf->mem)+i_subbuf*buf->subbuf_size;
  47                         valid_length = (unsigned long)buf->subbuf_size - header->lost_size;
  48                 }
  49                 else {
  50                         struct ltt_subbuffer_header *header = (struct ltt_subbuffer_header *)((char *)buf->mem)+i_subbuf*buf->subbuf_size;
  51
  52                         valid_length = commit_seq;
  53                         header->lost_size = buf->subbuf_size-valid_length;
  54                         assert(i_subbuf == last_subbuf);
  55                 }
  56
  57                 patient_write(buf->file_fd, buf->mem + i_subbuf * buf->subbuf_size, valid_length);
  58
  59                 /* pad with empty bytes */
  60                 tmp = malloc(buf->subbuf_size-valid_length);
  61                 memset(tmp, 0, buf->subbuf_size-valid_length);
  62                 patient_write(buf->file_fd, tmp, buf->subbuf_size-valid_length);
  63                 free(tmp);
  64
  65                 if(i_subbuf == last_subbuf)
  66                         break;
  67         }
  68 }
  69