2015-03-03 18:13:42 +01:00
|
|
|
/*
|
|
|
|
* QEMU generic buffers
|
|
|
|
*
|
|
|
|
* Copyright (c) 2015 Red Hat, Inc.
|
|
|
|
*
|
|
|
|
* This library is free software; you can redistribute it and/or
|
|
|
|
* modify it under the terms of the GNU Lesser General Public
|
|
|
|
* License as published by the Free Software Foundation; either
|
|
|
|
* version 2 of the License, or (at your option) any later version.
|
|
|
|
*
|
|
|
|
* This library is distributed in the hope that it will be useful,
|
|
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
|
|
* Lesser General Public License for more details.
|
|
|
|
*
|
|
|
|
* You should have received a copy of the GNU Lesser General Public
|
|
|
|
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
|
|
|
|
*
|
|
|
|
*/
|
|
|
|
|
2016-01-29 18:49:55 +01:00
|
|
|
#include "qemu/osdep.h"
|
2015-03-03 18:13:42 +01:00
|
|
|
#include "qemu/buffer.h"
|
2015-10-30 12:10:01 +01:00
|
|
|
#include "trace.h"
|
2015-03-03 18:13:42 +01:00
|
|
|
|
2015-10-30 12:10:00 +01:00
|
|
|
#define BUFFER_MIN_INIT_SIZE 4096
|
|
|
|
#define BUFFER_MIN_SHRINK_SIZE 65536
|
2015-10-30 12:09:56 +01:00
|
|
|
|
2016-03-14 10:58:29 +01:00
|
|
|
/* define the factor alpha for the exponential smoothing
|
2015-10-30 12:10:14 +01:00
|
|
|
* that is used in the average size calculation. a shift
|
|
|
|
* of 7 results in an alpha of 1/2^7. */
|
|
|
|
#define BUFFER_AVG_SIZE_SHIFT 7
|
|
|
|
|
2015-10-30 12:10:12 +01:00
|
|
|
static size_t buffer_req_size(Buffer *buffer, size_t len)
|
|
|
|
{
|
|
|
|
return MAX(BUFFER_MIN_INIT_SIZE,
|
|
|
|
pow2ceil(buffer->offset + len));
|
|
|
|
}
|
|
|
|
|
2015-10-30 12:10:13 +01:00
|
|
|
static void buffer_adj_size(Buffer *buffer, size_t len)
|
|
|
|
{
|
|
|
|
size_t old = buffer->capacity;
|
|
|
|
buffer->capacity = buffer_req_size(buffer, len);
|
|
|
|
buffer->buffer = g_realloc(buffer->buffer, buffer->capacity);
|
|
|
|
trace_buffer_resize(buffer->name ?: "unnamed",
|
|
|
|
old, buffer->capacity);
|
2015-10-30 12:10:14 +01:00
|
|
|
|
|
|
|
/* make it even harder for the buffer to shrink, reset average size
|
2016-03-14 10:58:29 +01:00
|
|
|
* to current capacity if it is larger than the average. */
|
2015-10-30 12:10:14 +01:00
|
|
|
buffer->avg_size = MAX(buffer->avg_size,
|
|
|
|
buffer->capacity << BUFFER_AVG_SIZE_SHIFT);
|
2015-10-30 12:10:13 +01:00
|
|
|
}
|
2015-10-30 12:10:12 +01:00
|
|
|
|
2015-10-30 12:09:57 +01:00
|
|
|
void buffer_init(Buffer *buffer, const char *name, ...)
|
|
|
|
{
|
|
|
|
va_list ap;
|
|
|
|
|
|
|
|
va_start(ap, name);
|
|
|
|
buffer->name = g_strdup_vprintf(name, ap);
|
|
|
|
va_end(ap);
|
|
|
|
}
|
|
|
|
|
2015-10-30 12:10:14 +01:00
|
|
|
static uint64_t buffer_get_avg_size(Buffer *buffer)
|
|
|
|
{
|
|
|
|
return buffer->avg_size >> BUFFER_AVG_SIZE_SHIFT;
|
|
|
|
}
|
|
|
|
|
2015-10-30 12:10:00 +01:00
|
|
|
void buffer_shrink(Buffer *buffer)
|
|
|
|
{
|
2015-10-30 12:10:14 +01:00
|
|
|
size_t new;
|
|
|
|
|
|
|
|
/* Calculate the average size of the buffer as
|
|
|
|
* avg_size = avg_size * ( 1 - a ) + required_size * a
|
|
|
|
* where a is 1 / 2 ^ BUFFER_AVG_SIZE_SHIFT. */
|
|
|
|
buffer->avg_size *= (1 << BUFFER_AVG_SIZE_SHIFT) - 1;
|
|
|
|
buffer->avg_size >>= BUFFER_AVG_SIZE_SHIFT;
|
|
|
|
buffer->avg_size += buffer_req_size(buffer, 0);
|
|
|
|
|
|
|
|
/* And then only shrink if the average size of the buffer is much
|
|
|
|
* too big, to avoid bumping up & down the buffers all the time.
|
|
|
|
* realloc() isn't exactly cheap ... */
|
|
|
|
new = buffer_req_size(buffer, buffer_get_avg_size(buffer));
|
|
|
|
if (new < buffer->capacity >> 3 &&
|
|
|
|
new >= BUFFER_MIN_SHRINK_SIZE) {
|
|
|
|
buffer_adj_size(buffer, buffer_get_avg_size(buffer));
|
2015-10-30 12:10:00 +01:00
|
|
|
}
|
|
|
|
|
2015-10-30 12:10:13 +01:00
|
|
|
buffer_adj_size(buffer, 0);
|
2015-10-30 12:10:00 +01:00
|
|
|
}
|
|
|
|
|
2015-03-03 18:13:42 +01:00
|
|
|
void buffer_reserve(Buffer *buffer, size_t len)
|
|
|
|
{
|
|
|
|
if ((buffer->capacity - buffer->offset) < len) {
|
2015-10-30 12:10:13 +01:00
|
|
|
buffer_adj_size(buffer, len);
|
2015-03-03 18:13:42 +01:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
gboolean buffer_empty(Buffer *buffer)
|
|
|
|
{
|
|
|
|
return buffer->offset == 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
uint8_t *buffer_end(Buffer *buffer)
|
|
|
|
{
|
|
|
|
return buffer->buffer + buffer->offset;
|
|
|
|
}
|
|
|
|
|
|
|
|
void buffer_reset(Buffer *buffer)
|
|
|
|
{
|
|
|
|
buffer->offset = 0;
|
2015-10-30 12:10:14 +01:00
|
|
|
buffer_shrink(buffer);
|
2015-03-03 18:13:42 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
void buffer_free(Buffer *buffer)
|
|
|
|
{
|
2015-10-30 12:10:01 +01:00
|
|
|
trace_buffer_free(buffer->name ?: "unnamed", buffer->capacity);
|
2015-03-03 18:13:42 +01:00
|
|
|
g_free(buffer->buffer);
|
2015-10-30 12:09:57 +01:00
|
|
|
g_free(buffer->name);
|
2015-03-03 18:13:42 +01:00
|
|
|
buffer->offset = 0;
|
|
|
|
buffer->capacity = 0;
|
|
|
|
buffer->buffer = NULL;
|
2015-10-30 12:09:57 +01:00
|
|
|
buffer->name = NULL;
|
2015-03-03 18:13:42 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
void buffer_append(Buffer *buffer, const void *data, size_t len)
|
|
|
|
{
|
|
|
|
memcpy(buffer->buffer + buffer->offset, data, len);
|
|
|
|
buffer->offset += len;
|
|
|
|
}
|
|
|
|
|
|
|
|
void buffer_advance(Buffer *buffer, size_t len)
|
|
|
|
{
|
|
|
|
memmove(buffer->buffer, buffer->buffer + len,
|
|
|
|
(buffer->offset - len));
|
|
|
|
buffer->offset -= len;
|
2015-10-30 12:10:14 +01:00
|
|
|
buffer_shrink(buffer);
|
2015-03-03 18:13:42 +01:00
|
|
|
}
|
2015-10-30 12:09:58 +01:00
|
|
|
|
|
|
|
void buffer_move_empty(Buffer *to, Buffer *from)
|
|
|
|
{
|
2015-10-30 12:10:01 +01:00
|
|
|
trace_buffer_move_empty(to->name ?: "unnamed",
|
|
|
|
from->offset,
|
|
|
|
from->name ?: "unnamed");
|
2015-10-30 12:09:58 +01:00
|
|
|
assert(to->offset == 0);
|
|
|
|
|
|
|
|
g_free(to->buffer);
|
|
|
|
to->offset = from->offset;
|
|
|
|
to->capacity = from->capacity;
|
|
|
|
to->buffer = from->buffer;
|
|
|
|
|
|
|
|
from->offset = 0;
|
|
|
|
from->capacity = 0;
|
|
|
|
from->buffer = NULL;
|
|
|
|
}
|
2015-10-30 12:09:59 +01:00
|
|
|
|
|
|
|
void buffer_move(Buffer *to, Buffer *from)
|
|
|
|
{
|
|
|
|
if (to->offset == 0) {
|
|
|
|
buffer_move_empty(to, from);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
|
2015-10-30 12:10:01 +01:00
|
|
|
trace_buffer_move(to->name ?: "unnamed",
|
|
|
|
from->offset,
|
|
|
|
from->name ?: "unnamed");
|
2015-10-30 12:09:59 +01:00
|
|
|
buffer_reserve(to, from->offset);
|
|
|
|
buffer_append(to, from->buffer, from->offset);
|
|
|
|
|
|
|
|
g_free(from->buffer);
|
|
|
|
from->offset = 0;
|
|
|
|
from->capacity = 0;
|
|
|
|
from->buffer = NULL;
|
|
|
|
}
|