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Some free-space optimizations
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@kriszyp
kriszyp committed Mar 5, 2024
1 parent 508ff99 commit e2108b0
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Showing 3 changed files with 118 additions and 87 deletions.
195 changes: 108 additions & 87 deletions dependencies/lmdb/libraries/liblmdb/mdb.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4096,36 +4096,86 @@ mdb_freelist_save(MDB_txn *txn)
txn->mt_loose_pgs = NULL;
txn->mt_loose_count = 0;
}
ssize_t reserved_space;
ssize_t reserved_space = -1;
ssize_t start_written = -1;
ssize_t end_written;
/* MDB_RESERVE cancels meminit in ovpage malloc (when no WRITEMAP) */
clean_limit = (env->me_flags & (MDB_NOMEMINIT|MDB_WRITEMAP))
? SSIZE_MAX : maxfree_1pg;

mop = env->me_pghead;
mop_len = (mop ? mop[0] : 0) + txn->mt_loose_count;
while(start_written != env->me_freelist_start || end_written != env->me_freelist_end || reserved_space != mop_len) {
mop_len = (mdb_midl_is_empty(mop) ? 0 : mop[0]) + txn->mt_loose_count;
while(reserved_space < mop_len ||
(start_written > env->me_freelist_start && env->me_freelist_start > 0) ||
freecnt < txn->mt_free_pgs[0]) {
/* Come back here after each Put() in case freelist changed */
if (start_written >= 0) {
fprintf(stderr, "Rerunning freelist save, start was %u is %u, length was %u is %u\n",start_written, env->me_freelist_start, reserved_space, mop_len);
}
MDB_val key, data;
pgno_t *pgs;
ssize_t j;

/* Save the IDL of pages freed by this txn, to a single record
* We do this first because sometimes this will end up exhausting the freelist
* so we don't have to write anything after this*/
if (freecnt < txn->mt_free_pgs[0]) {
if (!freecnt) {
/* Make sure last page of freeDB is touched and on freelist */
rc = mdb_page_search(&mc, NULL, MDB_PS_LAST|MDB_PS_MODIFY);
if (rc && rc != MDB_NOTFOUND)
return rc;
}
free_pgs = txn->mt_free_pgs;
/* Write to last page of freeDB */
key.mv_size = sizeof(txn->mt_txnid);
key.mv_data = &txn->mt_txnid;
do {
freecnt = free_pgs[0];
data.mv_size = MDB_IDL_SIZEOF(free_pgs);
fprintf(stderr, "write new freed pages, id: %u ", txn->mt_txnid);
mdb_midl_print(stderr, free_pgs);
rc = mdb_cursor_put(&mc, &key, &data, MDB_RESERVE);
if (rc)
return rc;
/* Retry if mt_free_pgs[] grew during the Put() */
free_pgs = txn->mt_free_pgs;
} while (freecnt < free_pgs[0]);
//mdb_midl_sort(free_pgs);
memcpy(data.mv_data, free_pgs, data.mv_size);
#if (MDB_DEBUG) > 1
{
unsigned int i = free_pgs[0];
DPRINTF(("IDL write txn %"Yu" root %"Yu" num %u",
txn->mt_txnid, txn->mt_dbs[FREE_DBI].md_root, i));
for (; i; i--)
DPRINTF(("IDL %"Yu, free_pgs[i]));
}
#endif
// continue;
}

/* Reserve records for me_pghead[]. Split it if multi-page,
* to avoid searching freeDB for a page range. Use keys in
* range [me_freelist_start me_freelist_end]: Smaller than txnid of oldest reader.
*/
head_id = start_written = env->me_freelist_start;
// TODO: We may want to the smallest id we can here (previous entry + 1)
txnid_t last_id_write = mop_len / maxfree_1pg + head_id;
reserved_space = mop_len;
if (mop_len && head_id <= last_id_write) {
if (!head_id) {
fprintf(stderr, "Invalid freelist start\n");
head_id = 1;
start_written = 1;
}
if (mop_len) {
// determine the size of the blocks we need
unsigned entry_size = ((mop_len / ((env->me_freelist_end - start_written) * maxfree_1pg)) + 1) * maxfree_1pg;
pglast = mop_len / entry_size + head_id;
fprintf(stderr, "Reserving in-memory freelist, length: %u, ids: ", mop_len);
while (head_id <= last_id_write) {
while (head_id <= pglast) {
key.mv_size = sizeof(head_id);
key.mv_data = &head_id;
int len = mop_len > maxfree_1pg ? maxfree_1pg : mop_len;
int len = mop_len > entry_size ? entry_size : mop_len;
mop_len -= len;
data.mv_size = (len + 2) * sizeof(pgno_t);
fprintf(stderr, "id: %u size: %u", head_id, data.mv_size);
Expand All @@ -4134,7 +4184,7 @@ mdb_freelist_save(MDB_txn *txn)
if (rc)
return rc;
}
}
} else pglast = head_id - 1;

/* If using records from freeDB which we have not yet
* deleted, delete them and any we reserved for me_pghead.
Expand All @@ -4153,53 +4203,16 @@ mdb_freelist_save(MDB_txn *txn)
mdb_tassert(txn, head_id >= env->me_freelist_start);
fprintf(stderr, "Deleting free list record %u\n", head_id);
rc = mdb_cursor_del(&mc, 0);
if (rc)
if (rc) {
last_error = "Attempting to delete free-space record";
return rc;
rc = mdb_cursor_get(&mc, &key, NULL, MDB_NEXT);
}
rc = mdb_cursor_get(&mc, &key, NULL, MDB_SET_RANGE);
} while (rc == MDB_SUCCESS);
pglast = env->me_freelist_start;
}
}
end_written = env->me_freelist_end;

/* Save the IDL of pages freed by this txn, to a single record */
if (freecnt < txn->mt_free_pgs[0]) {
if (!freecnt) {
/* Make sure last page of freeDB is touched and on freelist */
rc = mdb_page_search(&mc, NULL, MDB_PS_LAST|MDB_PS_MODIFY);
if (rc && rc != MDB_NOTFOUND)
return rc;
}
free_pgs = txn->mt_free_pgs;
/* Write to last page of freeDB */
key.mv_size = sizeof(txn->mt_txnid);
key.mv_data = &txn->mt_txnid;
do {
freecnt = free_pgs[0];
data.mv_size = MDB_IDL_SIZEOF(free_pgs);
fprintf(stderr, "write new freed pages, id: %u ", txn->mt_txnid);
mdb_midl_print(stderr, free_pgs);
rc = mdb_cursor_put(&mc, &key, &data, MDB_RESERVE);
if (rc)
return rc;
/* Retry if mt_free_pgs[] grew during the Put() */
free_pgs = txn->mt_free_pgs;
} while (freecnt < free_pgs[0]);
//mdb_midl_sort(free_pgs);
memcpy(data.mv_data, free_pgs, data.mv_size);
#if (MDB_DEBUG) > 1
{
unsigned int i = free_pgs[0];
DPRINTF(("IDL write txn %"Yu" root %"Yu" num %u",
txn->mt_txnid, txn->mt_dbs[FREE_DBI].md_root, i));
for (; i; i--)
DPRINTF(("IDL %"Yu, free_pgs[i]));
}
#endif
// continue;
}
mop = env->me_pghead;
mop_len = (mop ? mop[0] : 0) + txn->mt_loose_count;
mop_len = (mdb_midl_is_empty(mop) ? 0 : mop[0]) + txn->mt_loose_count;

}

Expand All @@ -4217,57 +4230,65 @@ mdb_freelist_save(MDB_txn *txn)
txn->mt_loose_count = 0;
mop = env->me_pghead;
mop_len = (mop ? mop[0] : 0) + txn->mt_loose_count;
if (mop_len > reserved_space) {
mop = mdb_midl_pack(env->me_pghead);
free(env->me_pghead);
env->me_pghead = mop;
mop_len = mop[0];
}
}

/* Fill in the reserved me_pghead records. Everything is finally
* in place, so this will not allocate or free any DB pages.
*/
rc = MDB_SUCCESS;
if (mop_len) {
MDB_val key, data;
MDB_val key, data;

/* Protect DB env from any (buggy) freelist use when saving mop */
MDB_IDL pghead = env->me_pghead;
env->me_pghead = NULL;
txn->mt_dirty_room = 0;
txnid_t last_id_write = mop_len / maxfree_1pg + start_written;
txnid_t id = start_written;
fprintf(stderr, "Writing in-memory freelist, length: %u ids: ", mop_len);
while (mop_len > 0) {
if (id > last_id_write) {
// we have written all the mop
fprintf(stderr, "Wrote all the mop, no room left\n");
return MDB_BAD_TXN;
}
key.mv_size = sizeof(id);
key.mv_data = &id;
fprintf(stderr, "put %u: ", id);
int len = maxfree_1pg;
ssize_t start = mop_len - len;
if (start < 0) {
len += start;
start = 0;
} else if (start > 0 && ((ssize_t)mop[start - 1] < 0)) {
// we need to write the previous page as well
len++;
start--;
}
MDB_ID save;
data.mv_size = (len + 1) * sizeof(MDB_ID);
save = mop[start];
/* Protect DB env from any (buggy) freelist use when saving mop */
MDB_IDL pghead = env->me_pghead;
env->me_pghead = NULL;
txn->mt_dirty_room = 0;

fprintf(stderr, "Writing in-memory freelist, length: %u ids: ", mop_len);
for (txnid_t id = start_written; id <= pglast; id++) {
key.mv_size = sizeof(id);
key.mv_data = &id;
mdb_cursor_get(&mc, &key, &data, MDB_SET_KEY);
fprintf(stderr, "put %u: ", id);

int len = (data.mv_size / sizeof(id)) - 1;
ssize_t start = mop_len - len;
if (start < 0) {
// oversized entry, we will copy in our data and fill the rest with zeros
len += start;
start = 0;
mdb_midl_print(stderr, mop);
rc = mdb_cursor_put(&mc, &key, &data, MDB_CURRENT & MDB_RESERVE);
if (rc) break;
memcpy(data.mv_data, mop, mop_len * sizeof(id));
memset((txnid_t*) data.mv_data + mop_len, 0, data.mv_size - mop_len * sizeof(id));
} else {
ssize_t save = mop[start];
ssize_t save2 = 0;
mop[start] = len;
mop_len -= len;
if (save < 0) {
// this would split an entry, so don't write the first byte,
// instead zero it out and don't count as many bytes used
mop_len++;
save2 = mop[start + 1];
mop[start + 1] = 0;
}
data.mv_data = &mop[start];
mdb_midl_print(stderr, &mop[start]);
rc = mdb_cursor_put(&mc, &key, &data, 0);
id++;
rc = mdb_cursor_put(&mc, &key, &data, MDB_CURRENT);
mop[start] = save;
mop_len -= len;
if (rc || !mop_len)
if (save2) mop[start + 1] = save2;
if (rc)
break;
}
fprintf(stderr, "\n");
env->me_pghead = pghead;
}
env->me_pghead = pghead;
/* Restore this so we can check vs. dirty_list after mdb_page_flush() */
if (! (txn->mt_flags & MDB_TXN_WRITEMAP))
txn->mt_loose_count += lost_loose;
Expand Down
9 changes: 9 additions & 0 deletions dependencies/lmdb/libraries/liblmdb/midl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -251,6 +251,15 @@ void mdb_midl_free(MDB_IDL ids)
free(ids-1);
}

int mdb_midl_is_empty(MDB_IDL idl) {
if (idl == NULL) return 1;
unsigned n = idl[0];
for (unsigned i = 1; i <= n; i++) {
if (idl[i]) return 0;
}
return 1;
}

void mdb_midl_shrink( MDB_IDL *idp )
{
MDB_IDL ids = *idp;
Expand Down
1 change: 1 addition & 0 deletions dependencies/lmdb/libraries/liblmdb/midl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -114,6 +114,7 @@ int mdb_midl_respread(MDB_IDL *idp);
int mdb_midl_print( FILE *fp, MDB_IDL ids );
MDB_IDL mdb_midl_pack(MDB_IDL idl);
unsigned mdb_midl_pack_count(MDB_IDL idl);
int mdb_midl_is_empty(MDB_IDL idl);

/** Insert an ID into an IDL.
* @param[in,out] idp Address of the IDL to append to.
Expand Down

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