+++ /dev/null
-/* Copyright (C) 2009 Pierre-Marc Fournier
- *
- * 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 2.1 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, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#include <stdlib.h>
-#include <assert.h>
-#include <byteswap.h>
-
-#include "ust/ustd.h"
-#include "buffers.h"
-#include "tracer.h"
-#include "usterr.h"
-
-/* This truncates to an offset in the buffer. */
-#define USTD_BUFFER_TRUNC(offset, bufinfo) \
- ((offset) & (~(((bufinfo)->subbuf_size*(bufinfo)->n_subbufs)-1)))
-
-#define LTT_MAGIC_NUMBER 0x00D6B7ED
-#define LTT_REV_MAGIC_NUMBER 0xEDB7D600
-
-/* Returns the size of a subbuffer size. This is the size that
- * will need to be written to disk.
- *
- * @subbuffer: pointer to the beginning of the subbuffer (the
- * beginning of its header)
- */
-
-size_t subbuffer_data_size(void *subbuf)
-{
- struct ltt_subbuffer_header *header = subbuf;
- int reverse;
- u32 data_size;
-
- if(header->magic_number == LTT_MAGIC_NUMBER) {
- reverse = 0;
- }
- else if(header->magic_number == LTT_REV_MAGIC_NUMBER) {
- reverse = 1;
- }
- else {
- return -1;
- }
-
- data_size = header->sb_size;
- if(reverse)
- data_size = bswap_32(data_size);
-
- return data_size;
-}
-
-
-void finish_consuming_dead_subbuffer(struct libustd_callbacks *callbacks, struct buffer_info *buf)
-{
- struct ust_buffer *ustbuf = buf->bufstruct_mem;
-
- long write_offset = uatomic_read(&ustbuf->offset);
- long consumed_offset = uatomic_read(&ustbuf->consumed);
-
- long i_subbuf;
-
- DBG("processing dead buffer (%s)", buf->name);
- DBG("consumed offset is %ld (%s)", consumed_offset, buf->name);
- DBG("write offset is %ld (%s)", write_offset, buf->name);
-
- /* First subbuf that we need to consume now. It is not modulo'd.
- * Consumed_offset is the next byte to consume. */
- long first_subbuf = consumed_offset / buf->subbuf_size;
- /* Last subbuf that we need to consume now. It is not modulo'd.
- * Write_offset is the next place to write so write_offset-1 is the
- * last place written. */
- long last_subbuf = (write_offset - 1) / buf->subbuf_size;
-
- DBG("first_subbuf=%ld", first_subbuf);
- DBG("last_subbuf=%ld", last_subbuf);
-
- if(last_subbuf - first_subbuf >= buf->n_subbufs) {
- DBG("an overflow has occurred, nothing can be recovered");
- return;
- }
-
- /* Iterate on subbuffers to recover. */
- for(i_subbuf = first_subbuf % buf->n_subbufs; ; i_subbuf++, i_subbuf %= buf->n_subbufs) {
- /* commit_seq is the offset in the buffer of the end of the last sequential commit.
- * Bytes beyond this limit cannot be recovered. This is a free-running counter. */
- long commit_seq = uatomic_read(&ustbuf->commit_seq[i_subbuf]);
-
- unsigned long valid_length = buf->subbuf_size;
- long n_subbufs_order = get_count_order(buf->n_subbufs);
- long commit_seq_mask = (~0UL >> n_subbufs_order);
-
- struct ltt_subbuffer_header *header = (struct ltt_subbuffer_header *)((char *)buf->mem+i_subbuf*buf->subbuf_size);
-
- if((commit_seq & commit_seq_mask) == 0) {
- /* There is nothing to do. */
- /* FIXME: is this needed? */
- break;
- }
-
- /* Check if subbuf was fully written. This is from Mathieu's algorithm/paper. */
- /* FIXME: not sure data_size = 0xffffffff when the buffer is not full. It might
- * take the value of the header size initially */
- if (((commit_seq - buf->subbuf_size) & commit_seq_mask)
- - (USTD_BUFFER_TRUNC(consumed_offset, buf) >> n_subbufs_order) == 0
- && header->data_size != 0xffffffff && header->sb_size != 0xffffffff) {
- /* If it was, we only check the data_size. This is the amount of valid data at
- * the beginning of the subbuffer. */
- valid_length = header->data_size;
- DBG("writing full subbuffer (%d) with valid_length = %ld", i_subbuf, valid_length);
- }
- else {
- /* If the subbuffer was not fully written, then we don't check data_size because
- * it hasn't been written yet. Instead we check commit_seq and use it to choose
- * a value for data_size. The viewer will need this value when parsing.
- */
-
- valid_length = commit_seq & (buf->subbuf_size-1);
- DBG("writing unfull subbuffer (%d) with valid_length = %ld", i_subbuf, valid_length);
- header->data_size = valid_length;
- header->sb_size = PAGE_ALIGN(valid_length);
- assert(i_subbuf == (last_subbuf % buf->n_subbufs));
- }
-
- if(callbacks->on_read_partial_subbuffer)
- callbacks->on_read_partial_subbuffer(callbacks, buf, i_subbuf, valid_length);
-
- if(i_subbuf == last_subbuf % buf->n_subbufs)
- break;
- }
-}
-
projects / ust.git / blobdiff