summaryrefslogtreecommitdiff
path: root/buffered_file.c
blob: f13443ee9135b7d4d75d85aa225ea9f3276cba5b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
/*
 * QEMU buffered QEMUFile
 *
 * Copyright IBM, Corp. 2008
 *
 * Authors:
 *  Anthony Liguori   <aliguori@us.ibm.com>
 *
 * This work is licensed under the terms of the GNU GPL, version 2.  See
 * the COPYING file in the top-level directory.
 *
 * Contributions after 2012-01-13 are licensed under the terms of the
 * GNU GPL, version 2 or (at your option) any later version.
 */

#include "qemu-common.h"
#include "hw/hw.h"
#include "qemu-timer.h"
#include "buffered_file.h"

//#define DEBUG_BUFFERED_FILE

typedef struct QEMUFileBuffered
{
    MigrationState *migration_state;
    QEMUFile *file;
    int freeze_output;
    size_t bytes_xfer;
    size_t xfer_limit;
    uint8_t *buffer;
    size_t buffer_size;
    size_t buffer_capacity;
    QEMUTimer *timer;
} QEMUFileBuffered;

#ifdef DEBUG_BUFFERED_FILE
#define DPRINTF(fmt, ...) \
    do { printf("buffered-file: " fmt, ## __VA_ARGS__); } while (0)
#else
#define DPRINTF(fmt, ...) \
    do { } while (0)
#endif

static void buffered_append(QEMUFileBuffered *s,
                            const uint8_t *buf, size_t size)
{
    if (size > (s->buffer_capacity - s->buffer_size)) {
        DPRINTF("increasing buffer capacity from %zu by %zu\n",
                s->buffer_capacity, size + 1024);

        s->buffer_capacity += size + 1024;

        s->buffer = g_realloc(s->buffer, s->buffer_capacity);
    }

    memcpy(s->buffer + s->buffer_size, buf, size);
    s->buffer_size += size;
}

static ssize_t buffered_flush(QEMUFileBuffered *s)
{
    size_t offset = 0;
    ssize_t ret = 0;

    DPRINTF("flushing %zu byte(s) of data\n", s->buffer_size);

    while (s->bytes_xfer < s->xfer_limit && offset < s->buffer_size) {

        ret = migrate_fd_put_buffer(s->migration_state, s->buffer + offset,
                                    s->buffer_size - offset);
        if (ret == -EAGAIN) {
            DPRINTF("backend not ready, freezing\n");
            ret = 0;
            s->freeze_output = 1;
            break;
        }

        if (ret <= 0) {
            DPRINTF("error flushing data, %zd\n", ret);
            break;
        } else {
            DPRINTF("flushed %zd byte(s)\n", ret);
            offset += ret;
            s->bytes_xfer += ret;
        }
    }

    DPRINTF("flushed %zu of %zu byte(s)\n", offset, s->buffer_size);
    memmove(s->buffer, s->buffer + offset, s->buffer_size - offset);
    s->buffer_size -= offset;

    if (ret < 0) {
        return ret;
    }
    return offset;
}

static int buffered_put_buffer(void *opaque, const uint8_t *buf, int64_t pos, int size)
{
    QEMUFileBuffered *s = opaque;
    ssize_t error;

    DPRINTF("putting %d bytes at %" PRId64 "\n", size, pos);

    error = qemu_file_get_error(s->file);
    if (error) {
        DPRINTF("flush when error, bailing: %s\n", strerror(-error));
        return error;
    }

    DPRINTF("unfreezing output\n");
    s->freeze_output = 0;

    if (size > 0) {
        DPRINTF("buffering %d bytes\n", size - offset);
        buffered_append(s, buf, size);
    }

    error = buffered_flush(s);
    if (error < 0) {
        DPRINTF("buffered flush error. bailing: %s\n", strerror(-error));
        return error;
    }

    if (pos == 0 && size == 0) {
        DPRINTF("file is ready\n");
        if (!s->freeze_output && s->bytes_xfer < s->xfer_limit) {
            DPRINTF("notifying client\n");
            migrate_fd_put_ready(s->migration_state);
        }
    }

    return size;
}

static int buffered_close(void *opaque)
{
    QEMUFileBuffered *s = opaque;
    ssize_t ret = 0;
    int ret2;

    DPRINTF("closing\n");

    s->xfer_limit = INT_MAX;
    while (!qemu_file_get_error(s->file) && s->buffer_size) {
        ret = buffered_flush(s);
        if (ret < 0) {
            break;
        }
        if (s->freeze_output) {
            ret = migrate_fd_wait_for_unfreeze(s->migration_state);
            if (ret < 0) {
                break;
            }
        }
    }

    ret2 = migrate_fd_close(s->migration_state);
    if (ret >= 0) {
        ret = ret2;
    }
    qemu_del_timer(s->timer);
    qemu_free_timer(s->timer);
    g_free(s->buffer);
    g_free(s);

    return ret;
}

/*
 * The meaning of the return values is:
 *   0: We can continue sending
 *   1: Time to stop
 *   negative: There has been an error
 */
static int buffered_get_fd(void *opaque)
{
    QEMUFileBuffered *s = opaque;

    return qemu_get_fd(s->file);
}

static int buffered_rate_limit(void *opaque)
{
    QEMUFileBuffered *s = opaque;
    int ret;

    ret = qemu_file_get_error(s->file);
    if (ret) {
        return ret;
    }
    if (s->freeze_output)
        return 1;

    if (s->bytes_xfer > s->xfer_limit)
        return 1;

    return 0;
}

static int64_t buffered_set_rate_limit(void *opaque, int64_t new_rate)
{
    QEMUFileBuffered *s = opaque;
    if (qemu_file_get_error(s->file)) {
        goto out;
    }
    if (new_rate > SIZE_MAX) {
        new_rate = SIZE_MAX;
    }

    s->xfer_limit = new_rate / 10;
    
out:
    return s->xfer_limit;
}

static int64_t buffered_get_rate_limit(void *opaque)
{
    QEMUFileBuffered *s = opaque;
  
    return s->xfer_limit;
}

static void buffered_rate_tick(void *opaque)
{
    QEMUFileBuffered *s = opaque;

    if (qemu_file_get_error(s->file)) {
        buffered_close(s);
        return;
    }

    qemu_mod_timer(s->timer, qemu_get_clock_ms(rt_clock) + 100);

    if (s->freeze_output)
        return;

    s->bytes_xfer = 0;

    buffered_put_buffer(s, NULL, 0, 0);
}

static const QEMUFileOps buffered_file_ops = {
    .get_fd =         buffered_get_fd,
    .put_buffer =     buffered_put_buffer,
    .close =          buffered_close,
    .rate_limit =     buffered_rate_limit,
    .get_rate_limit = buffered_get_rate_limit,
    .set_rate_limit = buffered_set_rate_limit,
};

QEMUFile *qemu_fopen_ops_buffered(MigrationState *migration_state)
{
    QEMUFileBuffered *s;

    s = g_malloc0(sizeof(*s));

    s->migration_state = migration_state;
    s->xfer_limit = migration_state->bandwidth_limit / 10;

    s->file = qemu_fopen_ops(s, &buffered_file_ops);

    s->timer = qemu_new_timer_ms(rt_clock, buffered_rate_tick, s);

    qemu_mod_timer(s->timer, qemu_get_clock_ms(rt_clock) + 100);

    return s->file;
}