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jstream.c
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jstream.c
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/*
* Copyright (c) 2004,2005 The DragonFly Project. All rights reserved.
*
* This code is derived from software contributed to The DragonFly Project
* by Matthew Dillon <dillon@backplane.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name of The DragonFly Project nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific, prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $DragonFly: src/sbin/jscan/jstream.c,v 1.8 2005/09/07 07:20:23 dillon Exp $
*/
#include "jscan.h"
static struct jhash *JHashAry[JHASH_SIZE];
static void jnormalize(struct jstream *js);
static int jaddrecord_backtrack(struct jsession *ss, struct jdata *jd);
/*
* Integrate a raw record. Deal with the transaction begin and end flags
* to create a forward-referenced collection of jstream records. If we are
* able to complete a transaction, the first js associated with that
* transaction is returned.
*
* XXX we need to store the data for very large multi-record transactions
* separately since it might not fit into memory.
*
* Note that a transaction might represent a huge I/O operation, resulting
* in an overall node structure that spans gigabytes, but individual
* subrecord leaf nodes are limited in size and we depend on this to simplify
* the handling of leaf records.
*
* A transaction may cover several raw records. The jstream collection for
* a transaction is only returned when the entire transaction has been
* successfully scanned. Due to the interleaving of transactions the ordering
* of returned JS's may be different (not exactly reversed) when scanning a
* journal backwards verses forwards. Since parallel operations are
* theoretically non-conflicting, this should not present a problem.
*/
struct jstream *
jaddrecord(struct jsession *ss, struct jdata *jd)
{
struct journal_rawrecbeg *head;
struct jstream *js;
struct jhash *jh;
struct jhash **jhp;
js = malloc(sizeof(struct jstream));
bzero(js, sizeof(struct jstream));
js->js_jdata = jref(jd);
js->js_head = (void *)jd->jd_data;
js->js_session = ss;
head = js->js_head;
/*
* Check for a completely self-contained transaction, just return the
* js if possible.
*/
if ((head->streamid & (JREC_STREAMCTL_BEGIN|JREC_STREAMCTL_END)) ==
(JREC_STREAMCTL_BEGIN|JREC_STREAMCTL_END)
) {
jnormalize(js);
return (js);
}
retry:
/*
* Check for an open transaction in the hash table.
*/
jhp = &JHashAry[head->streamid & JHASH_MASK];
while ((jh = *jhp) != NULL) {
if (jh->jh_session == ss &&
((jh->jh_transid ^ head->streamid) & JREC_STREAMID_MASK) == 0
) {
break;
}
jhp = &jh->jh_hash;
}
/*
* We might have picked up a transaction in the middle, which we
* detect by not finding a hash record coupled with a raw record
* whos JREC_STREAMCTL_BEGIN bit is not set (or JREC_STREAMCTL_END
* bit if we are scanning backwards).
*
* When this case occurs we have to backtrack to locate the
* BEGIN (END if scanning backwards) and collect those records
* in order to obtain a complete transaction.
*
* This case most often occurs when a batch operation runs in
* prefix set whos starting raw-record transaction id is in
* the middle of one or more meta-transactions. It's a bit of
* a tricky situation, but easily resolvable by scanning the
* prefix set backwards (forwards if originally scanning backwards)
* to locate the raw record representing the start (end) of the
* transaction.
*/
if (jh == NULL) {
if (ss->ss_direction == JD_FORWARDS &&
(head->streamid & JREC_STREAMCTL_BEGIN) == 0
) {
if (verbose_opt > 1)
fprintf(stderr, "mid-transaction detected transid %016llx streamid %04x\n", jd->jd_transid, head->streamid & JREC_STREAMID_MASK);
if (jaddrecord_backtrack(ss, jd) == 0) {
if (verbose_opt)
fprintf(stderr, "mid-transaction streamid %04x collection succeeded\n", head->streamid & JREC_STREAMID_MASK);
goto retry;
}
fprintf(stderr, "mid-transaction streamid %04x collection failed\n", head->streamid & JREC_STREAMID_MASK);
jscan_dispose(js);
return(NULL);
} else if (ss->ss_direction == JD_BACKWARDS &&
(head->streamid & JREC_STREAMCTL_END) == 0
) {
if (verbose_opt > 1)
fprintf(stderr, "mid-transaction detected transid %016llx streamid %04x\n", jd->jd_transid, head->streamid & JREC_STREAMID_MASK);
if (jaddrecord_backtrack(ss, jd) == 0) {
if (verbose_opt)
fprintf(stderr, "mid-transaction streamid %04x collection succeeded\n", head->streamid & JREC_STREAMID_MASK);
goto retry;
}
fprintf(stderr, "mid-transaction streamid %04x collection failed\n", head->streamid & JREC_STREAMID_MASK);
jscan_dispose(js);
return(NULL);
}
}
/*
* If we've made it to here and we still don't have a hash record
* to track the transaction, create one.
*/
if (jh == NULL) {
jh = malloc(sizeof(*jh));
bzero(jh, sizeof(*jh));
*jhp = jh;
jh->jh_first = js;
jh->jh_last = js;
jh->jh_transid = head->streamid;
jh->jh_session = ss;
return (NULL);
}
/*
* Emplace the stream segment
*/
jh->jh_transid |= head->streamid & JREC_STREAMCTL_MASK;
if (ss->ss_direction == JD_FORWARDS) {
jh->jh_last->js_next = js;
jh->jh_last = js;
} else {
js->js_next = jh->jh_first;
jh->jh_first = js;
}
/*
* If the transaction is complete, remove the hash entry and return the
* js representing the beginning of the transaction. Otherwise leave
* the hash entry intact and return NULL.
*/
if ((jh->jh_transid & (JREC_STREAMCTL_BEGIN|JREC_STREAMCTL_END)) ==
(JREC_STREAMCTL_BEGIN|JREC_STREAMCTL_END)
) {
*jhp = jh->jh_hash;
js = jh->jh_first;
free(jh);
jnormalize(js);
} else {
js = NULL;
}
return (js);
}
/*
* Renormalize the jscan list to remove all the meta record headers
* and trailers except for the very first one.
*/
static
void
jnormalize(struct jstream *js)
{
struct jstream *jscan;
off_t off;
js->js_normalized_off = 0;
js->js_normalized_base = (void *)js->js_head;
js->js_normalized_size = js->js_head->recsize - sizeof(struct journal_rawrecend);
js->js_normalized_total = js->js_normalized_size;
off = js->js_normalized_size;
for (jscan = js->js_next; jscan; jscan = jscan->js_next) {
jscan->js_normalized_off = off;
jscan->js_normalized_base = (char *)jscan->js_head +
sizeof(struct journal_rawrecbeg);
jscan->js_normalized_size = jscan->js_head->recsize -
sizeof(struct journal_rawrecbeg) -
sizeof(struct journal_rawrecend);
off += jscan->js_normalized_size;
js->js_normalized_total += jscan->js_normalized_size;
}
}
/*
* For sanity's sake I will describe the normal backtracking that must occur,
* but this routine must also operate on reverse-scanned (undo) records
* by forward tracking.
*
* A record has been found that represents the middle or end of a transaction
* when we were expecting the beginning of a transaction. We must backtrack
* to locate the start of the transaction, then process raw records relating
* to the transaction until we reach our current point (jd) again. If
* we find a matching streamid representing the end of a transaction instead
* of the expected start-of-transaction that record belongs to a wholely
* different meta-transaction and the record we seek is known to not be
* available.
*
* jd is the current record, directon is the normal scan direction (we have
* to scan in the reverse direction).
*/
static
int
jaddrecord_backtrack(struct jsession *ss, struct jdata *jd)
{
struct jfile *jf = ss->ss_jfin;
struct jdata *scan;
struct jstream *js;
u_int16_t streamid;
u_int16_t scanid;
assert(ss->ss_direction == JD_FORWARDS || ss->ss_direction == JD_BACKWARDS);
if (jmodes & JMODEF_INPUT_PIPE)
return(-1);
streamid = ((struct journal_rawrecbeg *)jd->jd_data)->streamid & JREC_STREAMID_MASK;
if (ss->ss_direction == JD_FORWARDS) {
/*
* Backtrack in the reverse direction looking for the transaction
* start bit. If we find an end bit instead it belongs to an
* unrelated transaction using the same streamid and there is no
* point continuing.
*/
scan = jref(jd);
while ((scan = jread(jf, scan, JD_BACKWARDS)) != NULL) {
scanid = ((struct journal_rawrecbeg *)scan->jd_data)->streamid;
if ((scanid & JREC_STREAMID_MASK) != streamid)
continue;
if (scanid & JREC_STREAMCTL_END) {
jfree(jf, scan);
return(-1);
}
if (scanid & JREC_STREAMCTL_BEGIN)
break;
}
/*
* Now jaddrecord the related records.
*/
while (scan != NULL && scan->jd_transid < jd->jd_transid) {
scanid = ((struct journal_rawrecbeg *)scan->jd_data)->streamid;
if ((scanid & JREC_STREAMID_MASK) == streamid) {
js = jaddrecord(ss, scan);
assert(js == NULL);
}
scan = jread(jf, scan, JD_FORWARDS);
}
if (scan == NULL)
return(-1);
jfree(jf, scan);
} else {
/*
* Backtrack in the forwards direction looking for the transaction
* end bit. If we find a start bit instead if belongs to an
* unrelated transaction using the same streamid and there is no
* point continuing.
*/
scan = jref(jd);
while ((scan = jread(jf, scan, JD_FORWARDS)) != NULL) {
scanid = ((struct journal_rawrecbeg *)scan->jd_data)->streamid;
if ((scanid & JREC_STREAMID_MASK) != streamid)
continue;
if (scanid & JREC_STREAMCTL_BEGIN) {
jfree(jf, scan);
return(-1);
}
if (scanid & JREC_STREAMCTL_END)
break;
}
/*
* Now jaddrecord the related records.
*/
while (scan != NULL && scan->jd_transid > jd->jd_transid) {
scanid = ((struct journal_rawrecbeg *)scan->jd_data)->streamid;
if ((scanid & JREC_STREAMID_MASK) == streamid) {
js = jaddrecord(ss, scan);
assert(js == NULL);
}
scan = jread(jf, scan, JD_BACKWARDS);
}
if (scan == NULL)
return(-1);
jfree(jf, scan);
}
return(0);
}
void
jscan_dispose(struct jstream *js)
{
struct jstream *jnext;
if (js->js_alloc_buf) {
free(js->js_alloc_buf);
js->js_alloc_buf = NULL;
js->js_alloc_size = 0;
}
while (js) {
jnext = js->js_next;
jfree(js->js_session->ss_jfin, js->js_jdata);
js->js_jdata = NULL;
free(js);
js = jnext;
}
}
/*
* Read the specified block of data out of a linked set of jstream
* structures. Returns 0 on success or an error code on error.
*/
int
jsread(struct jstream *js, off_t off, void *buf, int bytes)
{
const void *ptr;
int n;
while (bytes) {
n = jsreadany(js, off, &ptr);
if (n == 0)
return (ENOENT);
if (n > bytes)
n = bytes;
bcopy(ptr, buf, n);
buf = (char *)buf + n;
off += n;
bytes -= n;
}
return(0);
}
/*
* Read the specified block of data out of a linked set of jstream
* structures. Attempt to return a pointer into the data set but
* allocate and copy if that is not possible. Returns 0 on success
* or an error code on error.
*/
int
jsreadp(struct jstream *js, off_t off, const void **bufp,
int bytes)
{
int error = 0;
int n;
n = jsreadany(js, off, bufp);
if (n < bytes) {
if (js->js_alloc_size < bytes) {
if (js->js_alloc_buf)
free(js->js_alloc_buf);
js->js_alloc_buf = malloc(bytes);
js->js_alloc_size = bytes;
if (js->js_alloc_buf == NULL)
fprintf(stderr, "attempt to allocate %d bytes failed\n", bytes);
assert(js->js_alloc_buf != NULL);
}
error = jsread(js, off, js->js_alloc_buf, bytes);
if (error) {
*bufp = NULL;
} else {
*bufp = js->js_alloc_buf;
}
}
return(error);
}
int
jsreadcallback(struct jstream *js, ssize_t (*func)(int, const void *, size_t),
int fd, off_t off, int bytes)
{
const void *bufp;
int res;
int n;
int r;
res = 0;
while (bytes && (n = jsreadany(js, off, &bufp)) > 0) {
if (n > bytes)
n = bytes;
r = func(fd, bufp, n);
if (r != n) {
if (res == 0)
res = -1;
}
res += n;
bytes -= n;
off += n;
}
return(res);
}
/*
* Return the largest contiguous buffer starting at the specified offset,
* or 0.
*/
int
jsreadany(struct jstream *js, off_t off, const void **bufp)
{
struct jstream *scan;
int n;
if ((scan = js->js_cache) == NULL || scan->js_normalized_off > off)
scan = js;
while (scan && scan->js_normalized_off <= off) {
js->js_cache = scan;
if (scan->js_normalized_off + scan->js_normalized_size > off) {
n = (int)(off - scan->js_normalized_off);
*bufp = scan->js_normalized_base + n;
return(scan->js_normalized_size - n);
}
scan = scan->js_next;
}
return(0);
}