view audioDB-internals.h @ 406:c279adeb47f4 api-inversion

Slight rearrangement of insert code.

Move most of audiodb_insert() into a helper function to create an
adb_datum_t from an adb_insert_t.  (Most of the rest of it goes into
another helper function for cleaning up).

Now audiodb_insert() is small enough that it's plausible to move the
O2_FLAG_LARGE_ADB into it from audioDB::insert.  The plan is to add
support for the LARGE_ADB case in audiodb_insert(), at which point
audiodb_batchinsert() will Just Work, and we'll be able to delete
audioDB::batchinsert_large_adb (which is good, because it's an
almost-but-not-quite-identical copy of audioDB::batchinsert).

struct adb {
  char *path;
  int fd;
  int flags;
  adb_header_t *header;
  std::set<std::string> *keys;
};

/* We could go gcc-specific here and use typeof() instead of passing
 * in an explicit type.  Answers on a postcard as to whether that's a
 * good plan or not. */
#define mmap_or_goto_error(type, var, start, length) \
  { void *tmp = mmap(0, length, PROT_READ, MAP_SHARED, adb->fd, (start)); \
    if(tmp == (void *) -1) { \
      goto error; \
    } \
    var = (type) tmp; \
  }

#define maybe_munmap(table, length) \
  { if(table) { \
      munmap(table, length); \
    } \
  }

static inline int audiodb_sync_header(adb_t *adb) {
  off_t pos;
  pos = lseek(adb->fd, (off_t) 0, SEEK_CUR);
  if(pos == (off_t) -1) {
    goto error;
  }
  if(lseek(adb->fd, (off_t) 0, SEEK_SET) == (off_t) -1) {
    goto error;
  }
  if(write(adb->fd, adb->header, O2_HEADERSIZE) != O2_HEADERSIZE) {
    goto error;
  }

  /* can be fsync() if fdatasync() is racily exciting and new */
  fdatasync(adb->fd);
  if(lseek(adb->fd, pos, SEEK_SET) == (off_t) -1) {
    goto error;
  }
  return 0;

 error:
  return 1;
}