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/*
* 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 "qemu-char.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 void buffered_flush(QEMUFileBuffered *s)
{
size_t offset = 0;
DPRINTF("flushing %zu byte(s) of data\n", s->buffer_size);
while (s->bytes_xfer < s->xfer_limit && offset < s->buffer_size) {
ssize_t ret;
ret = migrate_fd_put_buffer(s->migration_state, s->buffer + offset,
s->buffer_size - offset);
if (ret == -EAGAIN) {
DPRINTF("backend not ready, freezing\n");
s->freeze_output = 1;
break;
}
if (ret <= 0) {
DPRINTF("error flushing data, %zd\n", ret);
qemu_file_set_error(s->file, 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;
}
static int buffered_put_buffer(void *opaque, const uint8_t *buf, int64_t pos, int size)
{
QEMUFileBuffered *s = opaque;
int 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);
}
buffered_flush(s);
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;
int ret;
DPRINTF("closing\n");
s->xfer_limit = INT_MAX;
while (!qemu_file_get_error(s->file) && s->buffer_size) {
buffered_flush(s);
if (s->freeze_output)
migrate_fd_wait_for_unfreeze(s->migration_state);
}
ret = migrate_fd_close(s->migration_state);
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_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);
}
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_put_buffer, NULL,
buffered_close, buffered_rate_limit,
buffered_set_rate_limit,
buffered_get_rate_limit);
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;
}
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