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212380e3 | 1 | Overview of the filedescriptor subsystem |
2 | Adrian Chadd <adrian@creative.net.au> | |
3 | ||
4 | $Id: fd-management.txt 6 2005-09-10 01:02:21Z nenolod $ | |
5 | ||
6 | ||
7 | Filedescriptor lists | |
8 | -------------------- | |
9 | ||
10 | The filedescriptor list is managed through the routines in fdlist.c . | |
11 | These include: | |
12 | ||
13 | fd_open() - tag an FD as "open" and active | |
14 | fd_close() - tag an FD as "closed" and close() the filedescriptor | |
15 | fd_note() - update the filedescriptor tag | |
16 | ||
17 | You can get the current list of open filedescriptors through /stats F as | |
18 | an oper. | |
19 | ||
20 | ||
21 | ||
22 | FD lists | |
23 | -------- | |
24 | ||
25 | The FD list support is very alpha. There are a few lists defined: | |
26 | ||
27 | typedef enum fdlist_t { | |
28 | FDLIST_NONE, | |
29 | FDLIST_SERVICE, | |
30 | FDLIST_SERVER, | |
31 | FDLIST_IDLECLIENT, | |
32 | FDLIST_BUSYCLIENT, | |
33 | FDLIST_MAX | |
34 | } fdlist_t; | |
35 | ||
36 | FDLIST_NONE Not on any list (ie close()d) | |
37 | FDLIST_SERVICE A service - listen() sockets, resolver, etc | |
38 | FDLIST_SERVER Server connections | |
39 | FDLIST_IDLECLIENT An idle client | |
40 | FDLIST_BUSYCLIENT A busy client | |
41 | FDLIST_MAX Used for bounds checking | |
42 | ||
43 | The idea is that the SERVICE sockets need polling frequently, the SERVER | |
44 | sockets also need polling frequently, BUSYCLIENT is for busy clients | |
45 | which need frequent polling (eg we're trying to write to them), and | |
46 | IDLECLIENT is for clients which we don't need to poll frequently. | |
47 | THIS hasn't been decided upon yet. | |
48 | ||
49 | ||
50 | ||
51 | File operations | |
52 | --------------- | |
53 | ||
54 | The file operations are also wrapped through file_open() and file_close() | |
55 | which handle calling fd_open() / fd_close() and tracking the filedescriptors | |
56 | correctly. fbopen() / fbclose() use file_open() / file_close() too. | |
57 | ||
58 | fileio.c defines the functions: | |
59 | ||
60 | int | |
61 | file_open(const char *filename, int mode, int fmode) | |
62 | ||
63 | A wrapper around open(filename, flags, mode). Read the open manpage for | |
64 | information. file_open() enforces filedescriptor limits and tags the FD | |
65 | through fd_open(). | |
66 | ||
67 | void | |
68 | file_close(int fd) | |
69 | ||
70 | A wrapper around close() for files. close() handles fd_close()ing the fd. | |
71 | ||
72 | ||
73 | FBFILE * | |
74 | fbopen(const char *filename, const char *mode) | |
75 | ||
76 | void | |
77 | fbclose(FBFILE *fb) | |
78 | ||
79 | These are the 'buffered disk IO' routines. You can read the code yourself. | |
80 | Note that these routines use file_open() and file_close(). | |
81 |