1#ifndef IOLOOPER_H
2#define IOLOOPER_H
3
4#include <stdint.h>
5
6/* An IOLooper is an abstraction for select() */
7
8typedef struct IoLooper  IoLooper;
9
10IoLooper*  iolooper_new(void);
11void       iolooper_free( IoLooper*  iol );
12void       iolooper_reset( IoLooper*  iol );
13
14void       iolooper_add_read( IoLooper*  iol, int  fd );
15void       iolooper_add_write( IoLooper*  iol, int  fd );
16void       iolooper_del_read( IoLooper*  iol, int  fd );
17void       iolooper_del_write( IoLooper*  iol, int  fd );
18
19enum {
20    IOLOOPER_READ = (1<<0),
21    IOLOOPER_WRITE = (1<<1),
22};
23void       iolooper_modify( IoLooper*  iol, int fd, int oldflags, int newflags);
24
25int        iolooper_poll( IoLooper*  iol );
26/* Wrapper around select()
27 * Return:
28 *  > 0 in case an I/O has occurred, or < 0 on error, or 0 on timeout with
29 *  errno set to ETIMEDOUT.
30 */
31int        iolooper_wait( IoLooper*  iol, int64_t  duration );
32
33int        iolooper_is_read( IoLooper*  iol, int  fd );
34int        iolooper_is_write( IoLooper*  iol, int  fd );
35/* Returns 1 if this IoLooper has one or more file descriptor to interact with */
36int        iolooper_has_operations( IoLooper*  iol );
37/* Gets current time in milliseconds.
38 * Return:
39 *  Number of milliseconds corresponded to the current time on success, or -1
40 *  on failure.
41 */
42int64_t    iolooper_now(void);
43/* Waits for an I/O to occur before specific absolute time.
44 * This routine should be used (instead of iolooper_wait) in cases when multiple
45 * sequential I/O should be completed within given time interval. For instance,
46 * consider the scenario, when "server" does two sequential writes, and "client"
47 * now has to read data transferred with these two distinct writes. It might be
48 * wasteful to do two reads, each with the same (large) timeout. Instead, it
49 * would be better to assign a deadline for both reads before the first read,
50 * and call iolooper_wait_absoulte with the same deadline value:
51 *  int64_t deadline = iolooper_now() + TIMEOUT;
52 *  if (iolooper_wait_absoulte(iol, deadline)) {
53 *      // Process first buffer.
54 *      (iolooper_wait_absoulte(iol, deadline)) {
55 *          // Process second read
56 *      }
57 *  }
58 * Param:
59 *  iol IoLooper instance for an I/O.
60 *  deadline Deadline (absoulte time in milliseconds) before which an I/O should
61 *      occur.
62 * Return:
63 *  Number of I/O descriptors set in iol, if an I/O has occurred, 0 if no I/O
64 *  occurred before the deadline, or -1 on error.
65 */
66int iolooper_wait_absolute(IoLooper* iol, int64_t deadline);
67
68#endif /* IOLOOPER_H */
69