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Add mdb_drop() for deleting a DB

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Allow MIDLs to grow arbitrarily, to allow unlimited number of
pages to be freed in one txn.
This commit is contained in:
Howard Chu 2011-09-18 12:37:02 -07:00
parent 09006ccec7
commit 57b5fbea49
4 changed files with 164 additions and 71 deletions
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148
libraries/libmdb/mdb.c
View File

@ -712,9 +712,8 @@ struct MDB_txn {
txnid_t mt_txnid;
MDB_env *mt_env; /**< the DB environment */
/** The list of pages that became unused during this transaction.
* This is an #IDL.
*/
pgno_t *mt_free_pgs;
IDL mt_free_pgs;
union {
ID2L dirty_list; /**< modified pages */
MDB_reader *reader; /**< this thread's slot in the reader table */
@ -845,7 +844,7 @@ struct MDB_env {
pthread_key_t me_txkey; /**< thread-key for readers */
MDB_page *me_dpages; /**< list of malloc'd blocks for re-use */
/** IDL of pages that became unused in a write txn */
pgno_t me_free_pgs[MDB_IDL_UM_SIZE];
IDL me_free_pgs;
/** ID2L of pages that were written during a write txn */
ID2 me_dirty_list[MDB_IDL_UM_SIZE];
/** rwlock for the DB tables, if #LAZY_LOCKS is false */
@ -908,6 +907,7 @@ static void mdb_cursor_init(MDB_cursor *mc, MDB_txn *txn, MDB_dbi dbi, MDB_xcurs
static void mdb_xcursor_init0(MDB_cursor *mc);
static void mdb_xcursor_init1(MDB_cursor *mc, MDB_node *node);
static int mdb_drop0(MDB_cursor *mc, int subs);
static void mdb_default_cmp(MDB_txn *txn, MDB_dbi dbi);
/** @cond */
@ -1135,7 +1135,7 @@ mdb_page_touch(MDB_cursor *mc)
return ENOMEM;
DPRINTF("touched db %u page %zu -> %zu", mc->mc_dbi, mp->mp_pgno, np->mp_pgno);
assert(mp->mp_pgno != np->mp_pgno);
mdb_midl_append(mc->mc_txn->mt_free_pgs, mp->mp_pgno);
mdb_midl_append(&mc->mc_txn->mt_free_pgs, mp->mp_pgno);
pgno = np->mp_pgno;
memcpy(np, mp, mc->mc_txn->mt_env->me_psize);
mp = np;
@ -1313,6 +1313,9 @@ mdb_txn_reset0(MDB_txn *txn)
MDB_page *dp;
unsigned int i;
if (mdb_midl_shrink(&txn->mt_free_pgs))
env->me_free_pgs = txn->mt_free_pgs;
/* return all dirty pages to dpage list */
for (i=1; i<=txn->mt_u.dirty_list[0].mid; i++) {
dp = txn->mt_u.dirty_list[i].mptr;
@ -1466,6 +1469,8 @@ mdb_txn_commit(MDB_txn *txn)
return rc;
}
} while (i != txn->mt_free_pgs[0]);
if (mdb_midl_shrink(&txn->mt_free_pgs))
env->me_free_pgs = txn->mt_free_pgs;
}
/* should only be one record now */
if (env->me_pghead) {
@ -1867,6 +1872,11 @@ mdb_env_create(MDB_env **env)
if (!e)
return ENOMEM;
e->me_free_pgs = mdb_midl_alloc();
if (!e->me_free_pgs) {
free(e);
return ENOMEM;
}
e->me_maxreaders = DEFAULT_READERS;
e->me_maxdbs = 2;
e->me_fd = INVALID_HANDLE_VALUE;
@ -2490,6 +2500,7 @@ mdb_env_close(MDB_env *env)
munmap(env->me_txns, (env->me_maxreaders-1)*sizeof(MDB_reader)+sizeof(MDB_txninfo));
}
close(env->me_lfd);
mdb_midl_free(env->me_free_pgs);
free(env);
}
@ -3848,45 +3859,10 @@ mdb_cursor_del(MDB_cursor *mc, unsigned int flags)
if (leaf->mn_flags & F_SUBDATA) {
/* add all the child DB's pages to the free list */
rc = mdb_page_search(&mc->mc_xcursor->mx_cursor, NULL, 0);
rc = mdb_drop0(&mc->mc_xcursor->mx_cursor, 0);
if (rc == MDB_SUCCESS) {
MDB_node *ni;
MDB_cursor *mx;
unsigned int i;
mx = &mc->mc_xcursor->mx_cursor;
mc->mc_db->md_entries -=
mx->mc_db->md_entries;
mdb_cursor_pop(mx);
while (mx->mc_snum > 0) {
for (i=0; i<NUMKEYS(mx->mc_pg[mx->mc_top]); i++) {
pgno_t pg;
ni = NODEPTR(mx->mc_pg[mx->mc_top], i);
pg = NODEPGNO(ni);
/* free it */
mdb_midl_append(mc->mc_txn->mt_free_pgs, pg);
}
if (!mx->mc_top)
break;
rc = mdb_cursor_sibling(mx, 1);
if (rc) {
/* no more siblings, go back to beginning
* of previous level. (stack was already popped
* by mdb_cursor_sibling)
*/
for (i=1; i<mx->mc_top; i++) {
pgno_t pg;
ni = NODEPTR(mx->mc_pg[i-1],0);
pg = NODEPGNO(ni);
if ((rc = mdb_page_get(mc->mc_txn, pg, &mx->mc_pg[i])))
break;
}
}
}
/* free it */
mdb_midl_append(mc->mc_txn->mt_free_pgs,
mx->mc_db->md_root);
mc->mc_xcursor->mx_db.md_entries;
}
}
}
@ -4584,7 +4560,7 @@ mdb_page_merge(MDB_cursor *csrc, MDB_cursor *cdst)
return rc;
}
mdb_midl_append(csrc->mc_txn->mt_free_pgs, csrc->mc_pg[csrc->mc_top]->mp_pgno);
mdb_midl_append(&csrc->mc_txn->mt_free_pgs, csrc->mc_pg[csrc->mc_top]->mp_pgno);
if (IS_LEAF(csrc->mc_pg[csrc->mc_top]))
csrc->mc_db->md_leaf_pages--;
else
@ -4646,11 +4622,11 @@ mdb_rebalance(MDB_cursor *mc)
mc->mc_db->md_root = P_INVALID;
mc->mc_db->md_depth = 0;
mc->mc_db->md_leaf_pages = 0;
mdb_midl_append(mc->mc_txn->mt_free_pgs, mc->mc_pg[mc->mc_top]->mp_pgno);
mdb_midl_append(&mc->mc_txn->mt_free_pgs, mc->mc_pg[mc->mc_top]->mp_pgno);
mc->mc_snum = 0;
} else if (IS_BRANCH(mc->mc_pg[mc->mc_top]) && NUMKEYS(mc->mc_pg[mc->mc_top]) == 1) {
DPUTS("collapsing root page!");
mdb_midl_append(mc->mc_txn->mt_free_pgs, mc->mc_pg[mc->mc_top]->mp_pgno);
mdb_midl_append(&mc->mc_txn->mt_free_pgs, mc->mc_pg[mc->mc_top]->mp_pgno);
mc->mc_db->md_root = NODEPGNO(NODEPTR(mc->mc_pg[mc->mc_top], 0));
if ((rc = mdb_page_get(mc->mc_txn, mc->mc_db->md_root,
&mc->mc_pg[mc->mc_top])))
@ -4734,7 +4710,7 @@ mdb_cursor_del0(MDB_cursor *mc, MDB_node *leaf)
ovpages = OVPAGES(NODEDSZ(leaf), mc->mc_txn->mt_env->me_psize);
for (i=0; i<ovpages; i++) {
DPRINTF("freed ov page %zu", pg);
mdb_midl_append(mc->mc_txn->mt_free_pgs, pg);
mdb_midl_append(&mc->mc_txn->mt_free_pgs, pg);
pg++;
}
}
@ -5289,22 +5265,90 @@ void mdb_close(MDB_env *env, MDB_dbi dbi)
free(ptr);
}
int mdb_drop(MDB_env *env, MDB_dbi dbi)
/** Add all the DB's pages to the free list.
* @param[in] mc Cursor on the DB to free.
* @param[in] subs non-Zero to check for sub-DBs in this DB.
* @return 0 on success, non-zero on failure.
*/
static int
mdb_drop0(MDB_cursor *mc, int subs)
{
MDB_txn *txn;
int rc;
if (!env || !dbi || dbi >= env->me_numdbs)
rc = mdb_page_search(mc, NULL, 0);
if (rc == MDB_SUCCESS) {
MDB_node *ni;
MDB_cursor mx;
unsigned int i;
/* LEAF2 pages have no nodes, cannot have sub-DBs */
if (!subs || IS_LEAF2(mc->mc_pg[mc->mc_top]))
mdb_cursor_pop(mc);
mdb_cursor_copy(mc, &mx);
while (mc->mc_snum > 0) {
if (IS_LEAF(mc->mc_pg[mc->mc_top])) {
for (i=0; i<NUMKEYS(mc->mc_pg[mc->mc_top]); i++) {
ni = NODEPTR(mc->mc_pg[mc->mc_top], i);
if (ni->mn_flags & F_SUBDATA) {
mdb_xcursor_init1(mc, ni);
rc = mdb_drop0(&mc->mc_xcursor->mx_cursor, 0);
if (rc)
return rc;
}
}
} else {
for (i=0; i<NUMKEYS(mc->mc_pg[mc->mc_top]); i++) {
pgno_t pg;
ni = NODEPTR(mc->mc_pg[mc->mc_top], i);
pg = NODEPGNO(ni);
/* free it */
mdb_midl_append(&mc->mc_txn->mt_free_pgs, pg);
}
}
if (!mc->mc_top)
break;
rc = mdb_cursor_sibling(mc, 1);
if (rc) {
/* no more siblings, go back to beginning
* of previous level. (stack was already popped
* by mdb_cursor_sibling)
*/
for (i=1; i<mc->mc_top; i++)
mc->mc_pg[i] = mx.mc_pg[i];
}
}
/* free it */
mdb_midl_append(&mc->mc_txn->mt_free_pgs,
mc->mc_db->md_root);
}
return 0;
}
int mdb_drop(MDB_txn *txn, MDB_dbi dbi, int del)
{
MDB_cursor *mc;
int rc;
if (!txn || !dbi || dbi >= txn->mt_numdbs)
return EINVAL;
if (env->me_txn)
return EBUSY;
rc = mdb_txn_begin(env, 0, &txn);
rc = mdb_cursor_open(txn, dbi, &mc);
if (rc)
return rc;
rc = mdb_drop0(mc, 1);
if (rc)
mdb_cursor_close(mc);
return rc;
if (del) {
rc = mdb_del(txn, MAIN_DBI, &mc->mc_dbx->md_name, NULL);
if (!rc)
mdb_close(txn->mt_env, dbi);
}
mdb_cursor_close(mc);
return rc;
}
int mdb_set_compare(MDB_txn *txn, MDB_dbi dbi, MDB_cmp_func *cmp)

25
libraries/libmdb/mdb.h
View File

@ -531,7 +531,9 @@ void mdb_txn_reset(MDB_txn *txn);
int mdb_txn_renew(MDB_txn *txn);
/** Open a database in the environment.
* The database handle may be discarded by calling #mdb_close().
* The database handle may be discarded by calling #mdb_close(). Only
* one thread should call this function; it is not mutex-protected in
* a read-only transaction.
* @param[in] txn A transaction handle returned by #mdb_txn_begin()
* @param[in] name The name of the database to open. If only a single
* database is needed in the enviroment, this value may be NULL.
@ -600,21 +602,16 @@ int mdb_stat(MDB_txn *txn, MDB_dbi dbi, MDB_stat *stat);
*/
void mdb_close(MDB_env *env, MDB_dbi dbi);
/** Delete a database and free all its pages.
* This function acquires its own write transaction to perform its
* work, so it must not be called if there is already an open write
* transaction in the environment. The database handle will also be
* closed as part of this operation.
* @param[in] env An environment handle returned by #mdb_env_create()
/** Delete a database and/or free all its pages.
* If the \b del parameter is non-zero the DB handle will be closed
* and the DB will be deleted.
* @param[in] txn A transaction handle returned by #mdb_txn_begin()
* @param[in] dbi A database handle returned by #mdb_open()
* @return A non-zero error value on failure and 0 on success. Some possible
* errors are:
* <ul>
* <li>EINVAL - an invalid parameter was specified.
* <li>EBUSY - there is already a write transaction.
* </ul>
* @param[in] del non-zero to delete the DB from the environment,
* otherwise just free its pages.
* @return A non-zero error value on failure and 0 on success.
*/
int mdb_drop(MDB_env *env, MDB_dbi dbi);
int mdb_drop(MDB_txn *txn, MDB_dbi dbi, int del);
/** Set a custom key comparison function for a database.
* The comparison function is called whenever it is necessary to compare a

40
libraries/libmdb/midl.c
View File

@ -17,6 +17,7 @@
#include <limits.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <assert.h>
#include "midl.h"
@ -117,11 +118,44 @@ int mdb_midl_insert( IDL ids, ID id )
}
#endif
int mdb_midl_append( IDL ids, ID id )
IDL mdb_midl_alloc()
{
IDL ids = malloc((MDB_IDL_UM_MAX+1) * sizeof(ID));
*ids++ = MDB_IDL_UM_MAX;
return ids;
}
void mdb_midl_free(IDL ids)
{
free(ids-1);
}
int mdb_midl_shrink( IDL *idp )
{
IDL ids = *idp;
if (ids[-1] > MDB_IDL_UM_MAX) {
ids = realloc(ids, (MDB_IDL_UM_MAX+1) * sizeof(ID));
*ids++ = MDB_IDL_UM_MAX;
*idp = ids;
return 1;
}
return 0;
}
int mdb_midl_append( IDL *idp, ID id )
{
IDL ids = *idp;
/* Too big? */
if (ids[0] >= MDB_IDL_UM_MAX)
return -1;
if (ids[0] >= ids[-1]) {
IDL idn = ids-1;
/* grow it */
idn = realloc(idn, (*idn + MDB_IDL_UM_MAX + 1) * sizeof(ID));
if (!idn)
return -1;
*idn++ += MDB_IDL_UM_MAX;
ids = idn;
*idp = ids;
}
ids[0]++;
ids[ids[0]] = id;
return 0;

22
libraries/libmdb/midl.h
View File

@ -111,12 +111,30 @@ typedef ID *IDL;
int mdb_midl_insert( IDL ids, ID id );
#endif
/** Allocate an IDL.
* Allocates memory for an IDL of a default size.
* @return IDL on success, NULL on failure.
*/
IDL mdb_midl_alloc();
/** Free an IDL.
* @param[in] ids The IDL to free.
*/
void mdb_midl_free(IDL ids);
/** Shrink an IDL.
* Return the IDL to the default size if it has grown larger.
* @param[in,out] idp Address of the IDL to shrink.
* @return 0 on no change, non-zero if shrunk.
*/
int mdb_midl_shrink(IDL *idp);
/** Append an ID onto an IDL.
* @param[in,out] ids The IDL to append to.
* @param[in,out] idp Address of the IDL to append to.
* @param[in] id The ID to append.
* @return 0 on success, -2 if the IDL is too large.
*/
int mdb_midl_append( IDL ids, ID id );
int mdb_midl_append( IDL *idp, ID id );
/** Sort an IDL.
* @param[in,out] ids The IDL to sort.