stdout: Try to write as much as possible in one go.
[paraslash.git] / stdout.c
1 /*
2 * Copyright (C) 2006-2009 Andre Noll <maan@systemlinux.org>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file stdout.c Functions that deal with writing to stdout. */
8
9 #include <dirent.h> /* readdir() */
10 #include <assert.h>
11 #include <stdbool.h>
12
13 #include "para.h"
14 #include "list.h"
15 #include "sched.h"
16 #include "fd.h"
17 #include "error.h"
18 #include "stdout.h"
19 #include "buffer_tree.h"
20
21 /**
22 * The pre_select function of the stdout task.
23 *
24 * \param s The scheduler this task was registered to.
25 * \param t The task structure of the stdout task.
26 *
27 * This function is always successful. If there is data available in the input
28 * buffer, it adds \p STDOUT_FILENO to the write fd set of \a s.
29 */
30 static void stdout_pre_select(struct sched *s, struct task *t)
31 {
32 struct stdout_task *sot = container_of(t, struct stdout_task, task);
33
34 t->error = 0;
35 sot->check_fd = 0;
36 if (!*sot->loaded) {
37 if (*sot->input_error < 0) {
38 t->error = *sot->input_error;
39 s->timeout.tv_sec = 0;
40 s->timeout.tv_usec = 1;
41 }
42 return;
43 }
44 sot->check_fd = 1;
45 para_fd_set(STDOUT_FILENO, &s->wfds, &s->max_fileno);
46 }
47
48 static void stdout_pre_select_btr(struct sched *s, struct task *t)
49 {
50 struct stdout_task *sot = container_of(t, struct stdout_task, task);
51 int ret;
52
53 t->error = 0;
54 sot->check_fd = 0;
55 ret = btr_node_status(sot->btrn, 0, BTR_NT_LEAF);
56 if (ret > 0)
57 para_fd_set(STDOUT_FILENO, &s->wfds, &s->max_fileno);
58 else if (ret < 0) {
59 s->timeout.tv_sec = 0;
60 s->timeout.tv_usec = 1;
61 }
62 }
63
64 /**
65 * The post select function of the stdout task.
66 *
67 * \param s The scheduler this task was registered to.
68 * \param t The task structure of the stdout task.
69 *
70 * This function checks if \p STDOUT_FILENO was included by in the write fd set
71 * of \a s during the previous pre_select call. If yes, and \p STDOUT_FILENO
72 * appeears to be writable, the data loaded in the input buffer is written to
73 * stdout.
74 */
75 static void stdout_post_select(struct sched *s, struct task *t)
76 {
77 struct stdout_task *sot = container_of(t, struct stdout_task, task);
78 ssize_t ret;
79
80 t->error = 0;
81 if (!sot->check_fd) {
82 if (!*sot->loaded && *sot->input_error < 0)
83 t->error = *sot->input_error;
84 return;
85 }
86 if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
87 return;
88 ret = write(STDOUT_FILENO, *sot->bufp, *sot->loaded);
89 if (ret < 0) {
90 t->error = -ERRNO_TO_PARA_ERROR(errno);
91 return;
92 }
93 *sot->loaded -= ret;
94 if (*sot->loaded)
95 memmove(*sot->bufp, *sot->bufp + ret, *sot->loaded);
96 }
97
98 static void stdout_post_select_btr(struct sched *s, struct task *t)
99 {
100 struct stdout_task *sot = container_of(t, struct stdout_task, task);
101 struct btr_node *btrn = sot->btrn;
102 int ret;
103 char *buf;
104 size_t sz;
105
106 t->error = 0;
107 ret = btr_node_status(btrn, 0, BTR_NT_LEAF);
108 if (ret < 0)
109 goto out;
110 if (ret == 0)
111 return;
112 if (!FD_ISSET(STDOUT_FILENO, &s->wfds))
113 return;
114
115 for (;;) {
116 sz = btr_next_buffer(btrn, &buf);
117 if (sz == 0)
118 break;
119 ret = write_nonblock(STDOUT_FILENO, buf, sz, 0);
120 if (ret <= 0)
121 break;
122 btr_consume(btrn, ret);
123 }
124 out:
125 if (ret < 0)
126 btr_remove_node(btrn);
127 t->error = ret;
128 }
129 /**
130 * Initialize a stdout task structure with default values.
131 *
132 * \param sot The stdout task structure.
133 *
134 * This fills in the pre/post select function pointers of the task structure
135 * given by \a sot.
136 */
137 void stdout_set_defaults(struct stdout_task *sot)
138 {
139 int ret;
140
141 if (sot->btrn) {
142 sot->task.pre_select = stdout_pre_select_btr;
143 sot->task.post_select = stdout_post_select_btr;
144 } else {
145 sot->task.pre_select = stdout_pre_select;
146 sot->task.post_select = stdout_post_select;
147 }
148 sprintf(sot->task.status, "stdout");
149 ret = mark_fd_nonblocking(STDOUT_FILENO);
150 if (ret >= 0)
151 return;
152 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
153 exit(EXIT_FAILURE);
154 }