Close cursors when commit(writer). Factor out code.

Close remaining cursors when committing a write txn. The doc says this
happens, and it avoids cursor tracking when updating mainDB + freeDB.

Rename mdb_cursor_merge() -> mdb_cursors_close() for code reuse,
and add a merge option.  Simplify its loop a bit.

Factor out cleanup of DBIs.

diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index d42f036741e81c49eedc88a226c21380ded29ec1..8254a886353747f5d28cdcb1d90cf7f68220d498 100644 (file)
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -1742,30 +1742,34 @@ mdb_cursor_shadow(MDB_txn *src, MDB_txn *dst)
        return MDB_SUCCESS;
 }
 
-/** Merge shadow cursors back into parent's */
+/** Close this write txn's cursors, after optionally merging its shadow
+ * cursors back into parent's.
+ * @param[in] txn the transaction handle.
+ * @param[in] merge 0 to not merge cursors, C_SHADOW to merge.
+ * @return 0 on success, non-zero on failure.
+ */
 static void
-mdb_cursor_merge(MDB_txn *txn)
+mdb_cursors_close(MDB_txn *txn, unsigned merge)
 {
-       MDB_dbi i;
-       for (i=0; i<txn->mt_numdbs; i++) {
-               if (txn->mt_cursors[i]) {
-                       MDB_cursor *mc;
-                       while ((mc = txn->mt_cursors[i])) {
-                               txn->mt_cursors[i] = mc->mc_next;
-                               if (mc->mc_flags & C_SHADOW) {
+       MDB_cursor **cursors = txn->mt_cursors, *mc, *next;
+       int i, j;
+
+       for (i = txn->mt_numdbs; --i >= 0; ) {
+               for (mc = cursors[i]; mc; mc = next) {
+                               next = mc->mc_next;
+                               if (mc->mc_flags & merge) {
                                        MDB_cursor *m2 = mc->mc_orig;
-                                       unsigned int j;
                                        m2->mc_snum = mc->mc_snum;
                                        m2->mc_top = mc->mc_top;
-                                       for (j=0; j<mc->mc_snum; j++) {
+                                       for (j = mc->mc_snum; --j >= 0; ) {
                                                m2->mc_pg[j] = mc->mc_pg[j];
                                                m2->mc_ki[j] = mc->mc_ki[j];
                                        }
                                }
                                if (mc->mc_flags & C_ALLOCD)
                                        free(mc);
-                       }
                }
+               cursors[i] = NULL;
        }
 }
 
@@ -1991,6 +1995,32 @@ mdb_txn_begin(MDB_env *env, MDB_txn *parent, unsigned int flags, MDB_txn **ret)
        return rc;
 }
 
+/** Export or close DBI handles opened in this txn. */
+static void
+mdb_dbis_update(MDB_txn *txn, int keep)
+{
+       int i;
+       MDB_dbi n = txn->mt_numdbs;
+       MDB_env *env = txn->mt_env;
+       unsigned char *tdbflags = txn->mt_dbflags;
+
+       for (i = n; --i >= 2;) {
+               if (tdbflags[i] & DB_NEW) {
+                       if (keep) {
+                               env->me_dbflags[i] = txn->mt_dbs[i].md_flags | MDB_VALID;
+                       } else {
+                               char *ptr = env->me_dbxs[i].md_name.mv_data;
+                               env->me_dbxs[i].md_name.mv_data = NULL;
+                               env->me_dbxs[i].md_name.mv_size = 0;
+                               env->me_dbflags[i] = 0;
+                               free(ptr);
+                       }
+               }
+       }
+       if (keep && env->me_numdbs < n)
+               env->me_numdbs = n;
+}
+
 /** Common code for #mdb_txn_reset() and #mdb_txn_abort().
  * May be called twice for readonly txns: First reset it, then abort.
  * @param[in] txn the transaction handle to reset
@@ -2002,15 +2032,7 @@ mdb_txn_reset0(MDB_txn *txn)
        unsigned int i;
 
        /* Close any DBI handles opened in this txn */
-       for (i=2; i<txn->mt_numdbs; i++) {
-               if (txn->mt_dbflags[i] & DB_NEW) {
-                       char *ptr = env->me_dbxs[i].md_name.mv_data;
-                       env->me_dbxs[i].md_name.mv_data = NULL;
-                       env->me_dbxs[i].md_name.mv_size = 0;
-                       env->me_dbflags[i] = 0;
-                       free(ptr);
-               }
-       }
+       mdb_dbis_update(txn, 0);
 
        if (F_ISSET(txn->mt_flags, MDB_TXN_RDONLY)) {
                if (txn->mt_u.reader) {
@@ -2023,17 +2045,7 @@ mdb_txn_reset0(MDB_txn *txn)
        } else {
                MDB_page *dp;
 
-               /* close(free) all cursors */
-               for (i=0; i<txn->mt_numdbs; i++) {
-                       if (txn->mt_cursors[i]) {
-                               MDB_cursor *mc;
-                               while ((mc = txn->mt_cursors[i])) {
-                                       txn->mt_cursors[i] = mc->mc_next;
-                                       if (mc->mc_flags & C_ALLOCD)
-                                               free(mc);
-                               }
-                       }
-               }
+               mdb_cursors_close(txn, 0);
 
                if (!(env->me_flags & MDB_WRITEMAP)) {
                        /* return all dirty pages to dpage list */
@@ -2133,13 +2145,7 @@ mdb_txn_commit(MDB_txn *txn)
        env = txn->mt_env;
 
        if (F_ISSET(txn->mt_flags, MDB_TXN_RDONLY)) {
-               /* update the DB flags */
-               for (i = 2; i<txn->mt_numdbs; i++) {
-                       if (txn->mt_dbflags[i] & DB_NEW)
-                               env->me_dbflags[i] = txn->mt_dbs[i].md_flags | MDB_VALID;
-               }
-               if (txn->mt_numdbs > env->me_numdbs)
-                       env->me_numdbs = txn->mt_numdbs;
+               mdb_dbis_update(txn, 1);
                txn->mt_numdbs = 2; /* so txn_abort() doesn't close any new handles */
                mdb_txn_abort(txn);
                return MDB_SUCCESS;
@@ -2168,8 +2174,8 @@ mdb_txn_commit(MDB_txn *txn)
                parent->mt_next_pgno = txn->mt_next_pgno;
                parent->mt_flags = txn->mt_flags;
 
-               /* Merge (and close) our cursors with parent's */
-               mdb_cursor_merge(txn);
+               /* Merge our cursors into parent's and close them */
+               mdb_cursors_close(txn, C_SHADOW);
 
                /* Update parent's DB table. */
                memcpy(parent->mt_dbs, txn->mt_dbs, txn->mt_numdbs * sizeof(MDB_db));
@@ -2228,6 +2234,8 @@ mdb_txn_commit(MDB_txn *txn)
                return EINVAL;
        }
 
+       mdb_cursors_close(txn, 0);
+
        if (!txn->mt_u.dirty_list[0].mid && !(txn->mt_flags & MDB_TXN_DIRTY))
                goto done;
 
@@ -2523,13 +2531,7 @@ sync:
 done:
        env->me_pglast = 0;
        env->me_txn = NULL;
-       /* update the DB flags */
-       for (i = 2; i<txn->mt_numdbs; i++) {
-               if (txn->mt_dbflags[i] & DB_NEW)
-                       env->me_dbflags[i] = txn->mt_dbs[i].md_flags | MDB_VALID;
-       }
-       if (txn->mt_numdbs > env->me_numdbs)
-               env->me_numdbs = txn->mt_numdbs;
+       mdb_dbis_update(txn, 1);
 
        UNLOCK_MUTEX_W(env);
        free(txn);