annotate audioDB-internals.h @ 416:6e6f4c1cc14d api-inversion

Initial implementation of accumulators for forthcoming audiodb_query().

Minimally tested using a temporary test harness; do not use as food.

As well as the necessary C++ magic, doodle in API header files aiming
vaguely for a sane API.

typedef struct adb_datum_internal {
  uint32_t nvectors;
  uint32_t dim;
  const char *key;
  void *data;
  void *times;
  void *power;
} adb_datum_internal_t;

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

typedef struct {
  bool operator() (const adb_result_t &r1, const adb_result_t &r2) {
    return strcmp(r1.key, r2.key) < 0;
  }
} adb_result_key_lt;

typedef struct {
  bool operator() (const adb_result_t &r1, const adb_result_t &r2) {
    return r1.qpos < r2.qpos;
  }
} adb_result_qpos_lt;

typedef struct {
  bool operator() (const adb_result_t &r1, const adb_result_t &r2) {
    return r1.dist < r2.dist;
  }
} adb_result_dist_lt;

typedef struct {
  bool operator() (const adb_result_t &r1, const adb_result_t &r2) {
    return r1.dist > r2.dist;
  }
} adb_result_dist_gt;

typedef struct {
  bool operator() (const adb_result_t &r1, const adb_result_t &r2) {
    return ((r1.ipos < r2.ipos) ||
            ((r1.ipos == r2.ipos) && 
             ((r1.qpos < r2.qpos) ||
              ((r1.qpos == r2.qpos) && (strcmp(r1.key, r2.key) < 0)))));
  }
} adb_result_triple_lt;

/* 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); \
    } \
  }

#define write_or_goto_error(fd, buffer, size) \
  { ssize_t tmp = size; \
    if(write(fd, buffer, size) != tmp) { \
      goto error; \
    } \
  }

#define read_or_goto_error(fd, buffer, size) \
  { ssize_t tmp = size; \
    if(read(fd, buffer, size) != tmp) { \
      goto error; \
    } \
  }

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;
}