X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=ustd%2Flowlevel.c;h=47a6f776e6dc5a9f92c90327c7bb88179e5e36f6;hb=920bdf719a175cc0e542e2f001e7d01f230412c1;hp=f386089e21b54f9c1a0b98cc351d26084deed454;hpb=0b0cd93782698872ea4778d29cd68091663ca367;p=ust.git diff --git a/ustd/lowlevel.c b/ustd/lowlevel.c index f386089..47a6f77 100644 --- a/ustd/lowlevel.c +++ b/ustd/lowlevel.c @@ -1,49 +1,151 @@ +/* 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 +#include + +#include "buffers.h" #include "tracer.h" #include "ustd.h" -#include "localerr.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 buffer_info *buf) { - struct ltt_channel_buf_struct *ltt_buf = buf->bufstruct_mem; + struct ust_buffer *ustbuf = buf->bufstruct_mem; - long write_offset = local_read(<t_buf->offset); - long consumed_offset = atomic_long_read(<t_buf->consumed); + long write_offset = local_read(&ustbuf->offset); + long consumed_offset = atomic_long_read(&ustbuf->consumed); long i_subbuf; - DBG("processing died buffer"); - DBG("consumed offset is %ld", consumed_offset); - DBG("write offset is %ld", write_offset); + 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; - long first_subbuf = write_offset / buf->subbuf_size; - long last_subbuf = consumed_offset / buf->subbuf_size; + DBG("first_subbuf=%ld", first_subbuf); + DBG("last_subbuf=%ld", last_subbuf); - if(last_subbuf - first_subbuf > buf->n_subbufs) { + if(last_subbuf - first_subbuf >= buf->n_subbufs) { DBG("an overflow has occurred, nothing can be recovered"); return; } - for(i_subbuf=first_subbuf; ; i_subbuf++, i_subbuf %= buf->n_subbufs) { - long commit_count = local_read(<t_buf->commit_count[i_subbuf]); + /* Iterate on subbuffers to recover. */ + for(i_subbuf = first_subbuf % buf->n_subbufs; ; i_subbuf++, i_subbuf %= buf->n_subbufs) { + void *tmp; + /* 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 = local_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_count_mask = (~0UL >> n_subbufs_order); - - /* check if subbuf was fully written */ - if (((commit_count - buf->subbuf_size) & commit_count_mask) - - (USTD_BUFFER_TRUNC(consumed_offset, buf) >> n_subbufs_order) - != 0) { - struct ltt_subbuffer_header *header = (struct ltt_subbuffer_header *)((char *)buf->mem)+i_subbuf*buf->subbuf_size; - valid_length = buf->subbuf_size - header->lost_size; + 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); + + int pad_size; + + if((commit_seq & commit_seq_mask) == 0) { + /* There is nothing to do. */ + /* FIXME: is this needed? */ + break; } - patient_write(buf->file_fd, buf->mem + i_subbuf * buf->subbuf_size, buf->subbuf_size); + /* 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; + } + 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); + header->data_size = valid_length; + header->sb_size = PAGE_ALIGN(valid_length); + assert(i_subbuf == (last_subbuf % buf->n_subbufs)); + } + + + patient_write(buf->file_fd, buf->mem + i_subbuf * buf->subbuf_size, valid_length); + + /* pad with empty bytes */ + pad_size = PAGE_ALIGN(valid_length)-valid_length; + if(pad_size) { + tmp = malloc(pad_size); + memset(tmp, 0, pad_size); + patient_write(buf->file_fd, tmp, pad_size); + free(tmp); + } - if(i_subbuf == last_subbuf) + if(i_subbuf == last_subbuf % buf->n_subbufs) break; } }