250 lines
11 KiB
C
250 lines
11 KiB
C
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/****************************************************************
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* *
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* Copyright 2006, 2009 Fidelity Information Services, Inc *
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* *
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* This source code contains the intellectual property *
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* of its copyright holder(s), and is made available *
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* under a license. If you do not know the terms of *
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* the license, please stop and do not read further. *
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* *
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****************************************************************/
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#include "mdef.h"
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#include "gtm_string.h"
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#include "gtm_socket.h"
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#include "gtm_inet.h"
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#include "gtm_fcntl.h"
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#include "gtm_unistd.h"
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#include "gtm_stat.h"
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#include <sys/time.h>
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#include <errno.h>
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#ifdef VMS
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#include <descrip.h> /* Required for gtmsource.h */
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#endif
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#include "gdsroot.h"
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#include "gdsblk.h"
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#include "gtm_facility.h"
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#include "fileinfo.h"
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#include "gdsbt.h"
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#include "gdsfhead.h"
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#include "filestruct.h"
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#include "repl_msg.h"
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#include "gtmsource.h"
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#include "jnl.h"
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#include "buddy_list.h"
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#include "hashtab_mname.h" /* needed for muprec.h */
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#include "hashtab_int4.h" /* needed for muprec.h */
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#include "hashtab_int8.h" /* needed for muprec.h */
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#include "muprec.h"
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#include "repl_ctl.h"
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#include "repl_errno.h"
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#include "repl_dbg.h"
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#include "memcoherency.h"
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#include "repl_tr_good.h"
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#include "min_max.h"
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#include "repl_instance.h"
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GBLREF jnlpool_addrs jnlpool;
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GBLREF gtmsource_state_t gtmsource_state;
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int gtmsource_readpool(uchar_ptr_t buff, int *data_len, int maxbufflen, boolean_t read_multiple, qw_num stop_read_at)
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{
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uint4 jnldata_len, read_size, read, jnlpool_size, avail_data;
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uint4 first_tr_len, num_tr_read, tr_len;
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int4 wrap_size;
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uchar_ptr_t buf_top, tr_p;
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jnlpool_ctl_ptr_t jctl;
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gtmsource_local_ptr_t gtmsource_local;
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sm_uc_ptr_t jnldata_base;
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jnldata_hdr_ptr_t jnl_header;
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qw_num read_addr, avail_data_qw;
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seq_num read_jnl_seqno, jnl_seqno, next_read_seqno, next_triple_seqno;
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jctl = jnlpool.jnlpool_ctl;
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jnlpool_size = jctl->jnlpool_size;
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DEBUG_ONLY(jnl_seqno = jctl->jnl_seqno;) /* jnl_seqno is used in an assert below. jnl_seqno is a local variable for
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* debugging purposes since shared memory can change from the time the assert
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* fails to the time the core gets created
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*/
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jnldata_base = jnlpool.jnldata_base;
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gtmsource_local = jnlpool.gtmsource_local;
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do
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{
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read = gtmsource_local->read;
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read_addr = gtmsource_local->read_addr;
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assert(stop_read_at > read_addr); /* there should be data to be read, if not how did we end up here? */
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read_jnl_seqno = gtmsource_local->read_jnl_seqno;
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assert(read_jnl_seqno <= gtmsource_local->next_triple_seqno);
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if (read_jnl_seqno == gtmsource_local->next_triple_seqno)
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{ /* Should signal a REPL_NEW_TRIPLE message to be sent first before sending any more seqnos across */
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gtmsource_state = gtmsource_local->gtmsource_state = GTMSOURCE_SEND_NEW_TRIPLE;
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return 0;
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}
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next_triple_seqno = gtmsource_local->next_triple_seqno;
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next_read_seqno = read_jnl_seqno;
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if (jnlpool_hasnt_overflowed(jctl, jnlpool_size, read_addr))
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{ /* No overflow yet. Before we read the content (including the jnldata_len read below), we have to ensure
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* we read up-to-date content. We rely on the memory barrier done in jnlpool_hasnt_overflowed for this.
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*/
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assert(read + SIZEOF(jnldata_hdr_struct) <= jnlpool_size);
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jnl_header = (jnldata_hdr_ptr_t)(jnldata_base + read);
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first_tr_len = jnldata_len = jnl_header->jnldata_len;
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if (read_multiple)
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{
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assert(stop_read_at >= read_addr);
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avail_data_qw = stop_read_at - read_addr;
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assert(maxbufflen <= MAXPOSINT4); /* to catch the case of change in type of maxbufflen */
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avail_data = (uint4)MIN(avail_data_qw, (qw_num)maxbufflen);
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read_multiple = (first_tr_len < avail_data);
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if (read_multiple)
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jnldata_len = avail_data;
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}
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if (SIZEOF(jnldata_hdr_struct) < jnldata_len && jnldata_len <= jnlpool_size)
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{
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read_size = jnldata_len - SIZEOF(jnldata_hdr_struct);
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if (0 < read_size && read_size <= maxbufflen)
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{
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if (0 < (wrap_size = (int4)(read - (jnlpool_size - jnldata_len))))
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read_size -= wrap_size;
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memcpy(buff, (sm_uc_ptr_t)jnl_header + SIZEOF(jnldata_hdr_struct), read_size);
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if (0 < wrap_size)
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memcpy(buff + read_size, jnldata_base, wrap_size);
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/* Now that we have read the content, we have to ensure that we haven't read content
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* that may been overwritten. We rely on the memory barrier done in
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* jnlpool_hasnt_overflowed for this
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*/
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if (jnlpool_hasnt_overflowed(jctl, jnlpool_size, read_addr))
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{ /* No overflow. Only now are we guaranteed a good value of "first_tr_len". */
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assert(first_tr_len % JNL_WRT_END_MODULUS == 0);
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REPL_DEBUG_ONLY(
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assert(repl_tr_good(buff, first_tr_len - SIZEOF(jnldata_hdr_struct),
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read_jnl_seqno));
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num_tr_read = 1;
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)
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next_read_seqno++;
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assert(next_read_seqno <= next_triple_seqno);
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if ((read_multiple) && (next_read_seqno < next_triple_seqno))
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{ /* Although stop_read_at - read_addr contains no partial transaction, it
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* is possible that stop_read_at - read_addr is more than maxbufflen, and
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* hence we read fewer bytes than stop_read_at - read_addr; scan what we
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* read to figure out if the tail is an incomplete transaction.
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*/
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assert(first_tr_len < jnldata_len); /* must hold if multiple transactions
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were read */
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tr_p = buff + first_tr_len - SIZEOF(jnldata_hdr_struct);
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buf_top = buff + jnldata_len - SIZEOF(jnldata_hdr_struct);
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while (SIZEOF(jnldata_hdr_struct) < (buf_top - tr_p))
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{ /* more than hdr available */
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tr_len = ((jnldata_hdr_ptr_t)tr_p)->jnldata_len;
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assert(tr_len % JNL_WRT_END_MODULUS == 0);
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assert(0 < tr_len);
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assert(tr_len <= jnlpool_size);
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if (tr_len <= (buf_top - tr_p)) /* transaction completely read */
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{ /* The message type and len assignments are a violation of
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* layering; ideally, this should be done in
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* gtmsource_process(), but we choose to do it here for
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* performance reasons. If we have to do it in
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* gtmsource_process(), we have to scan the buffer again.
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*/
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((repl_msg_ptr_t)tr_p)->type = REPL_TR_JNL_RECS;
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((repl_msg_ptr_t)tr_p)->len = tr_len;
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REPL_DEBUG_ONLY(
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assert(repl_tr_good(tr_p + REPL_MSG_HDRLEN,
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tr_len - REPL_MSG_HDRLEN,
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read_jnl_seqno + num_tr_read));
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num_tr_read++;
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)
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next_read_seqno++;
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tr_p += tr_len;
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if (next_read_seqno >= next_triple_seqno)
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{ /* Dont read more than boundary of next triple */
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assert(next_read_seqno == next_triple_seqno);
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break;
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}
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} else
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{
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REPL_DPRINT5("Partial transaction read since jnldata_len"
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" %llu larger than maxbufflen %d, tr_len %d, "
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"remaining buffer %d\n", avail_data_qw, maxbufflen,
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tr_len, buf_top - tr_p);
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break;
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}
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}
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REPL_DEBUG_ONLY(
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if (0 != (buf_top - tr_p))
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{
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REPL_DPRINT4("Partial tr header read since jnldata_len "
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"%llu larger than maxbufflen %d, incomplete header"
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" length %d\n", avail_data_qw, maxbufflen,
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buf_top - tr_p);
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}
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)
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jnldata_len = (uint4)((tr_p - buff) + SIZEOF(jnldata_hdr_struct));
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wrap_size = (int4)(read - (jnlpool_size - jnldata_len));
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}
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REPL_DPRINT4("Pool read seqno : "INT8_FMT" Num Tr read : %d Total Tr len : %d\n",
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INT8_PRINT(read_jnl_seqno), num_tr_read, jnldata_len);
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REPL_DPRINT4("Read %u : Next read : %u : %s\n", read,
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(0 > wrap_size) ? read + jnldata_len : wrap_size,
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(0 > wrap_size) ? "" : " READ WRAPPED");
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assert(next_read_seqno <= next_triple_seqno);
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/* Before sending the seqnos, check if a new triple got concurrently written */
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assert(gtmsource_local->next_triple_num <= gtmsource_local->num_triples);
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if ((gtmsource_local->next_triple_num == gtmsource_local->num_triples)
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&& (gtmsource_local->num_triples != jnlpool.repl_inst_filehdr->num_triples))
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{ /* We are sending seqnos of the last triple (that is open-ended) and
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* there has been at least one triple concurrently added to this instance
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* file compared to what is in our private memory. Set the next triple's
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* start_seqno and redo the read with the new "next_triple_seqno".
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*/
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assert(MAX_SEQNO == gtmsource_local->next_triple_seqno);
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gtmsource_set_next_triple_seqno(TRUE);
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/* Set the next triple's start_seqno and redo the read */
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if (GTMSOURCE_WAITING_FOR_CONNECTION == gtmsource_state)
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return 0;/* Connection reset in "gtmsource_set_next_triple_seqno" */
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continue;
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}
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read = ((0 > wrap_size) ? read + jnldata_len : wrap_size);
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read_addr += jnldata_len;
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read_jnl_seqno = next_read_seqno;
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assert(read_jnl_seqno <= gtmsource_local->next_triple_seqno);
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assert(stop_read_at >= read_addr);
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assert(jnl_seqno >= read_jnl_seqno - 1);
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/* In the rare case when we read the transaction read_jnl_seqno just as
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* it becomes available and before the GTM process that wrote it updates
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* jctl->jnl_seqno in t_end/tp_tend, we may return from this function
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* with read_jnl_seqno one more than jctl->jnl_seqno. This is such a rare
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* case that we don't want to add a wait loop for jctl->jnl_seqno to become
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* equal to read_jnl_seqno. We expect that by the time we send the just read
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* transaction(s) using socket I/O, jctl->jnl_seqno would have been updated.
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* In any case, we prevent ourselves from misinterpreting this condition when
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* read_jnl_seqno is compared against jctl->jnl_seqno in gtmsource_process(),
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* gtmsource_get_jnlrecs() and gtmsource_showbacklog().
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*/
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assert(read == read_addr % jnlpool_size);
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gtmsource_local->read = read;
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gtmsource_local->read_addr = read_addr;
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gtmsource_local->read_jnl_seqno = read_jnl_seqno;
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*data_len = first_tr_len - SIZEOF(jnldata_hdr_struct);
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return (jnldata_len);
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} /* else overflow happened, or about to happen */
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} else if (0 < read_size && jnlpool_hasnt_overflowed(jctl, jnlpool_size, read_addr))
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{ /* Buffer cannot accommodate data */
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*data_len = read_size;
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return (-1);
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} /* else
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* We read a corrupt (overwritten) large value, or read_size == 0, both of which imply overflow.
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* read_size == 0 => overflow because every transaction generates non-zero bytes of jnl data */
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} /* else
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* We read a corrupt (overwritten) large value, or read 0, both of which imply overflow.
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* jnldata_len == 0 => overflow because every transaction generates non-zero bytes of jnl data */
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} /* else overflow happened, or about to happen */
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break;
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} while (TRUE);
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*data_len = -1;
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return (-1); /* Error indication */
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}
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