Kill magic numbers for NUM_METAS, databases

diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index b78178e4c33c3c8fc3efa513f51ea9cf1481c296..8f29ec560c6be51b6de9188516cb789a25916fe6 100644 (file)
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -943,6 +943,11 @@ typedef struct MDB_db {
 #define        FREE_DBI        0
        /** Handle for the default DB. */
 #define        MAIN_DBI        1
+       /** Number of DBs in metapage (free and main) - also hardcoded elsewhere */
+#define CORE_DBS       2
+
+       /** Number of meta pages - also hardcoded elsewhere */
+#define NUM_METAS      2
 
        /** Meta page content.
         *      A meta page is the start point for accessing a database snapshot.
@@ -956,11 +961,11 @@ typedef struct MDB_meta {
        uint32_t        mm_version;
        void            *mm_address;            /**< address for fixed mapping */
        size_t          mm_mapsize;                     /**< size of mmap region */
-       MDB_db          mm_dbs[2];                      /**< first is free space, 2nd is main db */
+       MDB_db          mm_dbs[CORE_DBS];       /**< first is free space, 2nd is main db */
        /** The size of pages used in this DB */
-#define        mm_psize        mm_dbs[0].md_pad
+#define        mm_psize        mm_dbs[FREE_DBI].md_pad
        /** Any persistent environment flags. @ref mdb_env */
-#define        mm_flags        mm_dbs[0].md_flags
+#define        mm_flags        mm_dbs[FREE_DBI].md_flags
        pgno_t          mm_last_pg;                     /**< last used page in file */
        volatile txnid_t        mm_txnid;       /**< txnid that committed this page */
 } MDB_meta;
@@ -1175,7 +1180,7 @@ struct MDB_env {
        char            *me_path;               /**< path to the DB files */
        char            *me_map;                /**< the memory map of the data file */
        MDB_txninfo     *me_txns;               /**< the memory map of the lock file or NULL */
-       MDB_meta        *me_metas[2];   /**< pointers to the two meta pages */
+       MDB_meta        *me_metas[NUM_METAS];   /**< pointers to the two meta pages */
        void            *me_pbuf;               /**< scratch area for DUPSORT put() */
        MDB_txn         *me_txn;                /**< current write transaction */
        MDB_txn         *me_txn0;               /**< prealloc'd write transaction */
@@ -1624,9 +1629,10 @@ static void mdb_audit(MDB_txn *txn)
                        mdb_tassert(txn, rc == MDB_NOTFOUND);
                }
        }
-       if (freecount + count + 2 /* metapages */ != txn->mt_next_pgno) {
+       if (freecount + count + NUM_METAS != txn->mt_next_pgno) {
                fprintf(stderr, "audit: %lu freecount: %lu count: %lu total: %lu next_pgno: %lu\n",
-                       txn->mt_txnid, freecount, count+2, freecount+count+2, txn->mt_next_pgno);
+                       txn->mt_txnid, freecount, count+NUM_METAS,
+                       freecount+count+NUM_METAS, txn->mt_next_pgno);
        }
 }
 #endif
@@ -1895,7 +1901,7 @@ mdb_page_spill(MDB_cursor *m0, MDB_val *key, MDB_val *data)
        /* Estimate how much space this op will take */
        i = m0->mc_db->md_depth;
        /* Named DBs also dirty the main DB */
-       if (m0->mc_dbi > MAIN_DBI)
+       if (m0->mc_dbi >= CORE_DBS)
                i += txn->mt_dbs[MAIN_DBI].md_depth;
        /* For puts, roughly factor in the key+data size */
        if (key)
@@ -2664,7 +2670,7 @@ mdb_txn_renew0(MDB_txn *txn)
        }
 
        /* Copy the DB info and flags */
-       memcpy(txn->mt_dbs, meta->mm_dbs, 2 * sizeof(MDB_db));
+       memcpy(txn->mt_dbs, meta->mm_dbs, CORE_DBS * sizeof(MDB_db));
 
        /* Moved to here to avoid a data race in read TXNs */
        txn->mt_next_pgno = meta->mm_last_pg+1;
@@ -2673,7 +2679,7 @@ mdb_txn_renew0(MDB_txn *txn)
 
        /* Setup db info */
        txn->mt_numdbs = env->me_numdbs;
-       for (i=2; i<txn->mt_numdbs; i++) {
+       for (i=CORE_DBS; i<txn->mt_numdbs; i++) {
                x = env->me_dbflags[i];
                txn->mt_dbs[i].md_flags = x & PERSISTENT_FLAGS;
                txn->mt_dbflags[i] = (x & MDB_VALID) ? DB_VALID|DB_USRVALID|DB_STALE : 0;
@@ -2834,7 +2840,7 @@ mdb_dbis_update(MDB_txn *txn, int keep)
        MDB_env *env = txn->mt_env;
        unsigned char *tdbflags = txn->mt_dbflags;
 
-       for (i = n; --i >= 2;) {
+       for (i = n; --i >= CORE_DBS;) {
                if (tdbflags[i] & DB_NEW) {
                        if (keep) {
                                env->me_dbflags[i] = txn->mt_dbs[i].md_flags | MDB_VALID;
@@ -3356,9 +3362,9 @@ mdb_txn_commit(MDB_txn *txn)
                /* Update parent's DB table. */
                memcpy(parent->mt_dbs, txn->mt_dbs, txn->mt_numdbs * sizeof(MDB_db));
                parent->mt_numdbs = txn->mt_numdbs;
-               parent->mt_dbflags[0] = txn->mt_dbflags[0];
-               parent->mt_dbflags[1] = txn->mt_dbflags[1];
-               for (i=2; i<txn->mt_numdbs; i++) {
+               parent->mt_dbflags[FREE_DBI] = txn->mt_dbflags[FREE_DBI];
+               parent->mt_dbflags[MAIN_DBI] = txn->mt_dbflags[MAIN_DBI];
+               for (i=CORE_DBS; i<txn->mt_numdbs; i++) {
                        /* preserve parent's DB_NEW status */
                        x = parent->mt_dbflags[i] & DB_NEW;
                        parent->mt_dbflags[i] = txn->mt_dbflags[i] | x;
@@ -3459,14 +3465,14 @@ mdb_txn_commit(MDB_txn *txn)
            txn->mt_txnid, (void*)txn, (void*)env, txn->mt_dbs[MAIN_DBI].md_root));
 
        /* Update DB root pointers */
-       if (txn->mt_numdbs > 2) {
+       if (txn->mt_numdbs > CORE_DBS) {
                MDB_cursor mc;
                MDB_dbi i;
                MDB_val data;
                data.mv_size = sizeof(MDB_db);
 
                mdb_cursor_init(&mc, txn, MAIN_DBI, NULL);
-               for (i = 2; i < txn->mt_numdbs; i++) {
+               for (i = CORE_DBS; i < txn->mt_numdbs; i++) {
                        if (txn->mt_dbflags[i] & DB_DIRTY) {
                                if (TXN_DBI_CHANGED(txn, i)) {
                                        rc = MDB_BAD_DBI;
@@ -3527,7 +3533,7 @@ mdb_env_read_header(MDB_env *env, MDB_meta *meta)
         * Read both meta pages so we can use the latest one.
         */
 
-       for (i=off=0; i<2; i++, off = meta->mm_psize) {
+       for (i=off=0; i<NUM_METAS; i++, off += meta->mm_psize) {
 #ifdef _WIN32
                DWORD len;
                OVERLAPPED ov;
@@ -3580,11 +3586,11 @@ mdb_env_init_meta0(MDB_env *env, MDB_meta *meta)
        meta->mm_version = MDB_DATA_VERSION;
        meta->mm_mapsize = env->me_mapsize;
        meta->mm_psize = env->me_psize;
-       meta->mm_last_pg = 1;
+       meta->mm_last_pg = NUM_METAS-1;
        meta->mm_flags = env->me_flags & 0xffff;
-       meta->mm_flags |= MDB_INTEGERKEY;
-       meta->mm_dbs[0].md_root = P_INVALID;
-       meta->mm_dbs[1].md_root = P_INVALID;
+       meta->mm_flags |= MDB_INTEGERKEY; /* this is mm_dbs[FREE_DBI].md_flags */
+       meta->mm_dbs[FREE_DBI].md_root = P_INVALID;
+       meta->mm_dbs[MAIN_DBI].md_root = P_INVALID;
 }
 
 /** Write the environment parameters of a freshly created DB environment.
@@ -3617,7 +3623,7 @@ mdb_env_init_meta(MDB_env *env, MDB_meta *meta)
 
        psize = env->me_psize;
 
-       p = calloc(2, psize);
+       p = calloc(NUM_METAS, psize);
        if (!p)
                return ENOMEM;
 
@@ -3630,10 +3636,10 @@ mdb_env_init_meta(MDB_env *env, MDB_meta *meta)
        q->mp_flags = P_META;
        *(MDB_meta *)METADATA(q) = *meta;
 
-       DO_PWRITE(rc, env->me_fd, p, psize * 2, len, 0);
+       DO_PWRITE(rc, env->me_fd, p, psize * NUM_METAS, len, 0);
        if (!rc)
                rc = ErrCode();
-       else if ((unsigned) len == psize * 2)
+       else if ((unsigned) len == psize * NUM_METAS)
                rc = MDB_SUCCESS;
        else
                rc = ENOSPC;
@@ -3676,8 +3682,8 @@ mdb_env_write_meta(MDB_txn *txn)
 
        if (flags & MDB_WRITEMAP) {
                mp->mm_mapsize = mapsize;
-               mp->mm_dbs[0] = txn->mt_dbs[0];
-               mp->mm_dbs[1] = txn->mt_dbs[1];
+               mp->mm_dbs[FREE_DBI] = txn->mt_dbs[FREE_DBI];
+               mp->mm_dbs[MAIN_DBI] = txn->mt_dbs[MAIN_DBI];
                mp->mm_last_pg = txn->mt_next_pgno - 1;
 #if (__GNUC__ * 100 + __GNUC_MINOR__ >= 404) && /* TODO: portability */        \
        !(defined(__i386__) || defined(__x86_64__))
@@ -3708,8 +3714,8 @@ mdb_env_write_meta(MDB_txn *txn)
        metab.mm_last_pg = env->me_metas[toggle]->mm_last_pg;
 
        meta.mm_mapsize = mapsize;
-       meta.mm_dbs[0] = txn->mt_dbs[0];
-       meta.mm_dbs[1] = txn->mt_dbs[1];
+       meta.mm_dbs[FREE_DBI] = txn->mt_dbs[FREE_DBI];
+       meta.mm_dbs[MAIN_DBI] = txn->mt_dbs[MAIN_DBI];
        meta.mm_last_pg = txn->mt_next_pgno - 1;
        meta.mm_txnid = txn->mt_txnid;
 
@@ -3794,7 +3800,7 @@ mdb_env_create(MDB_env **env)
                return ENOMEM;
 
        e->me_maxreaders = DEFAULT_READERS;
-       e->me_maxdbs = e->me_numdbs = 2;
+       e->me_maxdbs = e->me_numdbs = CORE_DBS;
        e->me_fd = INVALID_HANDLE_VALUE;
        e->me_lfd = INVALID_HANDLE_VALUE;
        e->me_mfd = INVALID_HANDLE_VALUE;
@@ -3932,7 +3938,7 @@ mdb_env_set_maxdbs(MDB_env *env, MDB_dbi dbs)
 {
        if (env->me_map)
                return EINVAL;
-       env->me_maxdbs = dbs + 2; /* Named databases + main and free DB */
+       env->me_maxdbs = dbs + CORE_DBS;
        return MDB_SUCCESS;
 }
 
@@ -4774,7 +4780,7 @@ mdb_env_close0(MDB_env *env, int excl)
 
        /* Doing this here since me_dbxs may not exist during mdb_env_close */
        if (env->me_dbxs) {
-               for (i = env->me_maxdbs; --i > MAIN_DBI; )
+               for (i = env->me_maxdbs; --i >= CORE_DBS; )
                        free(env->me_dbxs[i].md_name.mv_data);
                free(env->me_dbxs);
        }
@@ -6170,7 +6176,7 @@ mdb_cursor_touch(MDB_cursor *mc)
 {
        int rc = MDB_SUCCESS;
 
-       if (mc->mc_dbi > MAIN_DBI && !(*mc->mc_dbflag & DB_DIRTY)) {
+       if (mc->mc_dbi >= CORE_DBS && !(*mc->mc_dbflag & DB_DIRTY)) {
                MDB_cursor mc2;
                MDB_xcursor mcx;
                if (TXN_DBI_CHANGED(mc->mc_txn, mc->mc_dbi))
@@ -7294,8 +7300,7 @@ mdb_cursor_open(MDB_txn *txn, MDB_dbi dbi, MDB_cursor **ret)
        if (txn->mt_flags & MDB_TXN_BLOCKED)
                return MDB_BAD_TXN;
 
-       /* Allow read access to the freelist */
-       if (!dbi && !F_ISSET(txn->mt_flags, MDB_TXN_RDONLY))
+       if (dbi == FREE_DBI && !F_ISSET(txn->mt_flags, MDB_TXN_RDONLY))
                return EINVAL;
 
        if (txn->mt_dbs[dbi].md_flags & MDB_DUPSORT)
@@ -8871,7 +8876,7 @@ mdb_env_copyfd1(MDB_env *env, HANDLE fd)
        my.mc_wlen[1] = 0;
        my.mc_olen[0] = 0;
        my.mc_olen[1] = 0;
-       my.mc_next_pgno = 2;
+       my.mc_next_pgno = NUM_METAS;
        my.mc_status = 0;
        my.mc_new = 1;
        my.mc_toggle = 0;
@@ -8884,7 +8889,7 @@ mdb_env_copyfd1(MDB_env *env, HANDLE fd)
                return rc;
 
        mp = (MDB_page *)my.mc_wbuf[0];
-       memset(mp, 0, 2*env->me_psize);
+       memset(mp, 0, NUM_METAS * env->me_psize);
        mp->mp_pgno = 0;
        mp->mp_flags = P_META;
        mm = (MDB_meta *)METADATA(mp);
@@ -8907,27 +8912,27 @@ mdb_env_copyfd1(MDB_env *env, HANDLE fd)
                mdb_cursor_init(&mc, txn, FREE_DBI, NULL);
                while ((rc = mdb_cursor_get(&mc, &key, &data, MDB_NEXT)) == 0)
                        freecount += *(MDB_ID *)data.mv_data;
-               freecount += txn->mt_dbs[0].md_branch_pages +
-                       txn->mt_dbs[0].md_leaf_pages +
-                       txn->mt_dbs[0].md_overflow_pages;
+               freecount += txn->mt_dbs[FREE_DBI].md_branch_pages +
+                       txn->mt_dbs[FREE_DBI].md_leaf_pages +
+                       txn->mt_dbs[FREE_DBI].md_overflow_pages;
 
                /* Set metapage 1 */
                mm->mm_last_pg = txn->mt_next_pgno - freecount - 1;
-               mm->mm_dbs[1] = txn->mt_dbs[1];
-               if (mm->mm_last_pg > 1) {
-                       mm->mm_dbs[1].md_root = mm->mm_last_pg;
+               mm->mm_dbs[MAIN_DBI] = txn->mt_dbs[MAIN_DBI];
+               if (mm->mm_last_pg > NUM_METAS-1) {
+                       mm->mm_dbs[MAIN_DBI].md_root = mm->mm_last_pg;
                        mm->mm_txnid = 1;
                } else {
-                       mm->mm_dbs[1].md_root = P_INVALID;
+                       mm->mm_dbs[MAIN_DBI].md_root = P_INVALID;
                }
        }
-       my.mc_wlen[0] = env->me_psize * 2;
+       my.mc_wlen[0] = env->me_psize * NUM_METAS;
        my.mc_txn = txn;
        pthread_mutex_lock(&my.mc_mutex);
        while(my.mc_new)
                pthread_cond_wait(&my.mc_cond, &my.mc_mutex);
        pthread_mutex_unlock(&my.mc_mutex);
-       rc = mdb_env_cwalk(&my, &txn->mt_dbs[1].md_root, 0);
+       rc = mdb_env_cwalk(&my, &txn->mt_dbs[MAIN_DBI].md_root, 0);
        if (rc == MDB_SUCCESS && my.mc_wlen[my.mc_toggle])
                rc = mdb_env_cthr_toggle(&my, 1);
        mdb_env_cthr_toggle(&my, -1);
@@ -8991,7 +8996,7 @@ mdb_env_copyfd0(MDB_env *env, HANDLE fd)
                }
        }
 
-       wsize = env->me_psize * 2;
+       wsize = env->me_psize * NUM_METAS;
        ptr = env->me_map;
        w2 = wsize;
        while (w2 > 0) {
@@ -9309,7 +9314,7 @@ int mdb_dbi_open(MDB_txn *txn, const char *name, unsigned int flags, MDB_dbi *db
 
        /* Is the DB already open? */
        len = strlen(name);
-       for (i=2; i<txn->mt_numdbs; i++) {
+       for (i=CORE_DBS; i<txn->mt_numdbs; i++) {
                if (!txn->mt_dbxs[i].md_name.mv_size) {
                        /* Remember this free slot */
                        if (!unused) unused = i;
@@ -9398,7 +9403,7 @@ mdb_stat(MDB_txn *txn, MDB_dbi dbi, MDB_stat *arg)
 void mdb_dbi_close(MDB_env *env, MDB_dbi dbi)
 {
        char *ptr;
-       if (dbi <= MAIN_DBI || dbi >= env->me_maxdbs)
+       if (dbi < CORE_DBS || dbi >= env->me_maxdbs)
                return;
        ptr = env->me_dbxs[dbi].md_name.mv_data;
        /* If there was no name, this was already closed */
@@ -9535,7 +9540,7 @@ int mdb_drop(MDB_txn *txn, MDB_dbi dbi, int del)
                goto leave;
 
        /* Can't delete the main DB */
-       if (del && dbi > MAIN_DBI) {
+       if (del && dbi >= CORE_DBS) {
                rc = mdb_del0(txn, MAIN_DBI, &mc->mc_dbx->md_name, NULL, F_SUBDATA);
                if (!rc) {
                        txn->mt_dbflags[dbi] = DB_STALE;