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Diffstat (limited to 'db2/lock/lock_deadlock.c')
-rw-r--r--db2/lock/lock_deadlock.c496
1 files changed, 496 insertions, 0 deletions
diff --git a/db2/lock/lock_deadlock.c b/db2/lock/lock_deadlock.c
new file mode 100644
index 0000000000..54a73afd1b
--- /dev/null
+++ b/db2/lock/lock_deadlock.c
@@ -0,0 +1,496 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 1996, 1997
+ * Sleepycat Software. All rights reserved.
+ */
+
+#include "config.h"
+
+#ifndef lint
+static const char copyright[] =
+"@(#) Copyright (c) 1997\n\
+ Sleepycat Software Inc. All rights reserved.\n";
+static const char sccsid[] = "@(#)lock_deadlock.c 10.20 (Sleepycat) 8/21/97";
+#endif
+
+#ifndef NO_SYSTEM_INCLUDES
+#include <sys/types.h>
+
+#include <errno.h>
+#include <string.h>
+#include <stdlib.h>
+#endif
+
+#include "db_int.h"
+#include "shqueue.h"
+#include "db_shash.h"
+#include "lock.h"
+#include "common_ext.h"
+
+#define ISSET_MAP(M, N) (M[(N) / 32] & (1 << (N) % 32))
+
+#define CLEAR_MAP(M, N) { \
+ u_int32_t __i; \
+ for (__i = 0; __i < (N); __i++) \
+ M[__i] = 0; \
+}
+
+#define SET_MAP(M, B) (M[(B) / 32] |= (1 << ((B) % 32)))
+#define CLR_MAP(M, B) (M[(B) / 32] &= ~(1 << ((B) % 32)))
+
+#define OR_MAP(D, S, N) { \
+ u_int32_t __i; \
+ for (__i = 0; __i < (N); __i++) \
+ D[__i] |= S[__i]; \
+}
+#define BAD_KILLID 0xffffffff
+
+typedef struct {
+ int valid;
+ u_int32_t id;
+ DB_LOCK last_lock;
+} locker_info;
+
+static int __dd_abort __P((DB_ENV *, locker_info *));
+static int __dd_build __P((DB_ENV *, u_int32_t **, int *, locker_info **));
+#ifdef DEBUG
+static void __dd_debug __P((DB_ENV *, locker_info *, u_int32_t *, int));
+#endif
+static u_int32_t
+ *__dd_find __P((u_int32_t *, locker_info *, u_int32_t));
+
+int
+lock_detect(lt, flags, atype)
+ DB_LOCKTAB *lt;
+ int flags;
+ u_int32_t atype;
+{
+ DB_ENV *dbenv;
+ locker_info *idmap;
+ u_int32_t *bitmap, *deadlock, killid;
+ int do_pass, i, nlockers, nentries, ret;
+
+ /* Validate arguments. */
+ if ((ret =
+ __db_fchk(lt->dbenv, "lock_detect", flags, DB_LOCK_CONFLICT)) != 0)
+ return (ret);
+
+ /* Check if a detector run is necessary. */
+ do_pass = 1;
+ dbenv = lt->dbenv;
+ if (LF_ISSET(DB_LOCK_CONFLICT)) {
+ /* Make a pass every time a lock waits. */
+ LOCK_LOCKREGION(lt);
+ do_pass = dbenv->lk_info->region->need_dd != 0;
+ UNLOCK_LOCKREGION(lt);
+ }
+
+ if (!do_pass)
+ return (0);
+
+ /* Build the waits-for bitmap. */
+ if ((ret = __dd_build(dbenv, &bitmap, &nlockers, &idmap)) != 0)
+ return (ret);
+
+ if (nlockers == 0)
+ return (0);
+#ifdef DEBUG
+ if (dbenv->db_verbose != 0)
+ __dd_debug(dbenv, idmap, bitmap, nlockers);
+#endif
+ /* Find a deadlock. */
+ deadlock = __dd_find(bitmap, idmap, nlockers);
+ nentries = ALIGN(nlockers, 32) / 32;
+ killid = BAD_KILLID;
+ if (deadlock != NULL) {
+ /* Kill someone. */
+ switch (atype) {
+ case DB_LOCK_OLDEST:
+ /*
+ * Find the first bit set in the current
+ * array and then look for a lower tid in
+ * the array.
+ */
+ for (i = 0; i < nlockers; i++)
+ if (ISSET_MAP(deadlock, i))
+ killid = i;
+
+ if (killid == BAD_KILLID) {
+ __db_err(dbenv,
+ "warning: could not find %s",
+ "locker to abort");
+ break;
+ }
+
+ /*
+ * The oldest transaction has the lowest
+ * transaction id.
+ */
+ for (i = killid + 1; i < nlockers; i++)
+ if (ISSET_MAP(deadlock, i) &&
+ idmap[i].id < idmap[killid].id)
+ killid = i;
+ break;
+ case DB_LOCK_DEFAULT:
+ case DB_LOCK_RANDOM:
+ /*
+ * We are trying to calculate the id of the
+ * locker whose entry is indicated by deadlock.
+ * We know that this is less than nlockers, so
+ * the cast below is valid.
+ */
+ killid =
+ (u_int32_t)((deadlock - bitmap) / nentries);
+ break;
+ case DB_LOCK_YOUNGEST:
+ /*
+ * Find the first bit set in the current
+ * array and then look for a lower tid in
+ * the array.
+ */
+ for (i = 0; i < nlockers; i++)
+ if (ISSET_MAP(deadlock, i))
+ killid = i;
+
+ if (killid == BAD_KILLID) {
+ __db_err(dbenv,
+ "warning: could not find %s",
+ "locker to abort");
+ break;
+ }
+ /*
+ * The youngest transaction has the highest
+ * transaction id.
+ */
+ for (i = killid + 1; i < nlockers; i++)
+ if (ISSET_MAP(deadlock, i) &&
+ idmap[i].id > idmap[killid].id)
+ killid = i;
+ break;
+ default:
+ killid = BAD_KILLID;
+ ret = EINVAL;
+ }
+
+ /* Kill the locker with lockid idmap[killid]. */
+ if (dbenv->db_verbose != 0 && killid != BAD_KILLID)
+ __db_err(dbenv, "Aborting locker %lx",
+ (u_long)idmap[killid].id);
+
+ if (killid != BAD_KILLID &&
+ (ret = __dd_abort(dbenv, &idmap[killid])) != 0)
+ __db_err(dbenv,
+ "warning: unable to abort locker %lx",
+ (u_long)idmap[killid].id);
+ }
+ free(bitmap);
+ free(idmap);
+
+ return (ret);
+}
+
+/*
+ * ========================================================================
+ * Utilities
+ */
+static int
+__dd_build(dbenv, bmp, nlockers, idmap)
+ DB_ENV *dbenv;
+ u_int32_t **bmp;
+ int *nlockers;
+ locker_info **idmap;
+{
+ DB_LOCKTAB *lt;
+ DB_LOCKOBJ *op, *lockerp;
+ struct __db_lock *lp;
+ u_int32_t *bitmap, count, *entryp, i, id, nentries, *tmpmap;
+ locker_info *id_array;
+ int is_first, ret;
+
+ lt = dbenv->lk_info;
+
+ /*
+ * We'll check how many lockers there are, add a few more in for
+ * good measure and then allocate all the structures. Then we'll
+ * verify that we have enough room when we go back in and get the
+ * mutex the second time.
+ */
+ LOCK_LOCKREGION(lt);
+retry: count = lt->region->nlockers;
+ lt->region->need_dd = 0;
+ UNLOCK_LOCKREGION(lt);
+
+ if (count == 0) {
+ *nlockers = 0;
+ return (0);
+ }
+
+ if (dbenv->db_verbose)
+ __db_err(dbenv, "%lu lockers", (u_long)count);
+
+ count += 10;
+ nentries = ALIGN(count, 32) / 32;
+ /*
+ * Allocate enough space for a count by count bitmap matrix.
+ *
+ * XXX
+ * We can probably save the malloc's between iterations just
+ * reallocing if necessary because count grew by too much.
+ */
+ if ((bitmap = (u_int32_t *)calloc((size_t)count,
+ sizeof(u_int32_t) * nentries)) == NULL) {
+ __db_err(dbenv, "%s", strerror(ENOMEM));
+ return (ENOMEM);
+ }
+
+ if ((tmpmap =
+ (u_int32_t *)calloc(sizeof(u_int32_t), nentries)) == NULL) {
+ __db_err(dbenv, "%s", strerror(ENOMEM));
+ free(bitmap);
+ return (ENOMEM);
+ }
+
+ if ((id_array = (locker_info *)calloc((size_t)count,
+ sizeof(locker_info))) == NULL) {
+ __db_err(dbenv, "%s", strerror(ENOMEM));
+ free(bitmap);
+ free(tmpmap);
+ return (ENOMEM);
+ }
+
+ /*
+ * Now go back in and actually fill in the matrix.
+ */
+ LOCK_LOCKREGION(lt);
+ if (lt->region->nlockers > count) {
+ free(bitmap);
+ free(tmpmap);
+ free(id_array);
+ goto retry;
+ }
+
+ /*
+ * First we go through and assign each locker a deadlock detector id.
+ * Note that we fill in the idmap in the next loop since that's the
+ * only place where we conveniently have both the deadlock id and the
+ * actual locker.
+ */
+ for (id = 0, i = 0; i < lt->region->table_size; i++)
+ for (op = SH_TAILQ_FIRST(&lt->hashtab[i], __db_lockobj);
+ op != NULL; op = SH_TAILQ_NEXT(op, links, __db_lockobj))
+ if (op->type == DB_LOCK_LOCKER)
+ op->dd_id = id++;
+ /*
+ * We go through the hash table and find each object. For each object,
+ * we traverse the waiters list and add an entry in the waitsfor matrix
+ * for each waiter/holder combination.
+ */
+ for (i = 0; i < lt->region->table_size; i++) {
+ for (op = SH_TAILQ_FIRST(&lt->hashtab[i], __db_lockobj);
+ op != NULL; op = SH_TAILQ_NEXT(op, links, __db_lockobj)) {
+ if (op->type != DB_LOCK_OBJTYPE)
+ continue;
+ CLEAR_MAP(tmpmap, nentries);
+
+ /*
+ * First we go through and create a bit map that
+ * represents all the holders of this object.
+ */
+ for (lp = SH_TAILQ_FIRST(&op->holders, __db_lock);
+ lp != NULL;
+ lp = SH_TAILQ_NEXT(lp, links, __db_lock)) {
+ if ((errno = __lock_getobj(lt, lp->holder,
+ NULL, DB_LOCK_LOCKER, &lockerp)) != 0) {
+ __db_err(dbenv,
+ "warning unable to find object");
+ continue;
+ }
+ id_array[lockerp->dd_id].id = lp->holder;
+ id_array[lockerp->dd_id].valid = 1;
+
+ /*
+ * If the holder has already been aborted, then
+ * we should ignore it for now.
+ */
+ if (lp->status == DB_LSTAT_HELD)
+ SET_MAP(tmpmap, lockerp->dd_id);
+ }
+
+ /*
+ * Next, for each waiter, we set its row in the matrix
+ * equal to the map of holders we set up above.
+ */
+ for (is_first = 1,
+ lp = SH_TAILQ_FIRST(&op->waiters, __db_lock);
+ lp != NULL;
+ is_first = 0,
+ lp = SH_TAILQ_NEXT(lp, links, __db_lock)) {
+ if ((ret = __lock_getobj(lt,
+ lp->holder, NULL, DB_LOCK_LOCKER, &lockerp))
+ != 0) {
+ __db_err(dbenv,
+ "warning unable to find object");
+ continue;
+ }
+ id_array[lockerp->dd_id].id = lp->holder;
+ id_array[lockerp->dd_id].valid = 1;
+
+ /*
+ * If the transaction is pending abortion, then
+ * ignore it on this iteration.
+ */
+ if (lp->status != DB_LSTAT_WAITING)
+ continue;
+
+ entryp = bitmap + (nentries * lockerp->dd_id);
+ OR_MAP(entryp, tmpmap, nentries);
+ /*
+ * If this is the first waiter on the queue,
+ * then we remove the waitsfor relationship
+ * with oneself. However, if it's anywhere
+ * else on the queue, then we have to keep
+ * it and we have an automatic deadlock.
+ */
+ if (is_first)
+ CLR_MAP(entryp, lockerp->dd_id);
+ }
+ }
+ }
+
+ /* Now for each locker; record its last lock. */
+ for (id = 0; id < count; id++) {
+ if (!id_array[id].valid)
+ continue;
+ if ((ret = __lock_getobj(lt,
+ id_array[id].id, NULL, DB_LOCK_LOCKER, &lockerp)) != 0) {
+ __db_err(dbenv,
+ "No locks for locker %lu", (u_long)id_array[id].id);
+ continue;
+ }
+ lp = SH_LIST_FIRST(&lockerp->heldby, __db_lock);
+ if (lp != NULL)
+ id_array[id].last_lock = LOCK_TO_OFFSET(lt, lp);
+ }
+
+ /* Pass complete, reset the deadlock detector bit. */
+ lt->region->need_dd = 0;
+ UNLOCK_LOCKREGION(lt);
+
+ /*
+ * Now we can release everything except the bitmap matrix that we
+ * created.
+ */
+ *nlockers = id;
+ *idmap = id_array;
+ *bmp = bitmap;
+ free(tmpmap);
+ return (0);
+}
+
+static u_int32_t *
+__dd_find(bmp, idmap, nlockers)
+ u_int32_t *bmp;
+ locker_info *idmap;
+ u_int32_t nlockers;
+{
+ u_int32_t i, j, nentries, *mymap, *tmpmap;
+
+ /*
+ * For each locker, or in the bits from the lockers
+ * on which that locker is waiting.
+ */
+ nentries = ALIGN(nlockers, 32) / 32;
+ for (mymap = bmp, i = 0; i < nlockers; i++, mymap += nentries) {
+ if (!idmap[i].valid)
+ continue;
+ for (j = 0; j < nlockers; j++) {
+ if (ISSET_MAP(mymap, j)) {
+ /* Find the map for this bit. */
+ tmpmap = bmp + (nentries * j);
+ OR_MAP(mymap, tmpmap, nentries);
+ if (ISSET_MAP(mymap, i))
+ return (mymap);
+ }
+ }
+ }
+ return (NULL);
+}
+
+static int
+__dd_abort(dbenv, info)
+ DB_ENV *dbenv;
+ locker_info *info;
+{
+ DB_LOCKTAB *lt;
+ DB_LOCKOBJ *lockerp, *sh_obj;
+ struct __db_lock *lockp;
+ int ret;
+
+ lt = dbenv->lk_info;
+ LOCK_LOCKREGION(lt);
+
+ /* Find the locker's last lock. */
+ if ((ret =
+ __lock_getobj(lt, info->id, NULL, DB_LOCK_LOCKER, &lockerp)) != 0)
+ goto out;
+
+ lockp = SH_LIST_FIRST(&lockerp->heldby, __db_lock);
+ if (LOCK_TO_OFFSET(lt, lockp) != info->last_lock ||
+ lockp == NULL || lockp->status != DB_LSTAT_WAITING)
+ goto out;
+
+ /* Abort lock, take it off list, and wake up this lock. */
+ lockp->status = DB_LSTAT_ABORTED;
+ lt->region->ndeadlocks++;
+ SH_LIST_REMOVE(lockp, locker_links, __db_lock);
+ sh_obj = (DB_LOCKOBJ *)((u_int8_t *)lockp + lockp->obj);
+ SH_TAILQ_REMOVE(&sh_obj->waiters, lockp, links, __db_lock);
+ (void)__db_mutex_unlock(&lockp->mutex, lt->fd);
+
+ ret = 0;
+
+out: UNLOCK_LOCKREGION(lt);
+ return (ret);
+}
+
+#ifdef DEBUG
+static void
+__dd_debug(dbenv, idmap, bitmap, nlockers)
+ DB_ENV *dbenv;
+ locker_info *idmap;
+ u_int32_t *bitmap;
+ int nlockers;
+{
+ u_int32_t *mymap;
+ int i, j, nentries;
+ char *msgbuf;
+
+ __db_err(dbenv, "Waitsfor array");
+ __db_err(dbenv, "waiter\twaiting on");
+ /*
+ * Alloc space to print 10 bytes per item waited on.
+ */
+ if ((msgbuf = (char *)malloc((nlockers + 1) * 10 + 64)) == NULL) {
+ errno = ENOMEM;
+ __db_err(dbenv, "%s", strerror(errno));
+ return;
+ }
+
+ nentries = ALIGN(nlockers, 32) / 32;
+ for (mymap = bitmap, i = 0; i < nlockers; i++, mymap += nentries) {
+ if (!idmap[i].valid)
+ continue;
+ sprintf(msgbuf, "%lx\t\t", (u_long)idmap[i].id);/* Waiter. */
+ for (j = 0; j < nlockers; j++)
+ if (ISSET_MAP(mymap, j))
+ sprintf(msgbuf, "%s %lx", msgbuf,
+ (u_long)idmap[j].id);
+ (void)sprintf(msgbuf,
+ "%s %lu", msgbuf, (u_long)idmap[i].last_lock);
+ __db_err(dbenv, msgbuf);
+ }
+
+ free(msgbuf);
+}
+#endif
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