libmdb: Don't open datafile twice when not needed.

If the database is opened with MDB_RDONLY or MDB_NOSYNC,
instead use the same file descriptor for me_mfd and me_fd.

Also factor out Windows/Unix error handling after open.

diff --git a/libraries/libmdb/mdb.c b/libraries/libmdb/mdb.c
index 879841e..cd3a759 100644 (file)
--- a/libraries/libmdb/mdb.c
+++ b/libraries/libmdb/mdb.c
@@ -2983,41 +2983,38 @@ mdb_env_open(MDB_env *env, const char *path, unsigned int flags, mode_t mode)
                len = OPEN_ALWAYS;
        }
        mode = FILE_ATTRIBUTE_NORMAL;
-       if ((env->me_fd = CreateFile(dpath, oflags, FILE_SHARE_READ|FILE_SHARE_WRITE,
-                       NULL, len, mode, NULL)) == INVALID_HANDLE_VALUE) {
-               rc = ErrCode();
-               goto leave;
-       }
+       env->me_fd = CreateFile(dpath, oflags, FILE_SHARE_READ|FILE_SHARE_WRITE,
+               NULL, len, mode, NULL);
 #else
        if (F_ISSET(flags, MDB_RDONLY))
                oflags = O_RDONLY;
        else
                oflags = O_RDWR | O_CREAT;
 
-       if ((env->me_fd = open(dpath, oflags, mode)) == -1) {
+       env->me_fd = open(dpath, oflags, mode);
+#endif
+       if (env->me_fd == INVALID_HANDLE_VALUE) {
                rc = ErrCode();
                goto leave;
        }
-#endif
 
        if ((rc = mdb_env_open2(env, flags)) == MDB_SUCCESS) {
-               /* synchronous fd for meta writes */
+               if (flags & (MDB_RDONLY|MDB_NOSYNC)) {
+                       env->me_mfd = env->me_fd;
+               } else {
+                       /* synchronous fd for meta writes */
 #ifdef _WIN32
-               if (!(flags & (MDB_RDONLY|MDB_NOSYNC)))
-                       mode |= FILE_FLAG_WRITE_THROUGH;
-               if ((env->me_mfd = CreateFile(dpath, oflags, FILE_SHARE_READ|FILE_SHARE_WRITE,
-                       NULL, len, mode, NULL)) == INVALID_HANDLE_VALUE) {
-                       rc = ErrCode();
-                       goto leave;
-               }
+                       env->me_mfd = CreateFile(dpath, oflags,
+                               FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, len,
+                               mode | FILE_FLAG_WRITE_THROUGH, NULL);
 #else
-               if (!(flags & (MDB_RDONLY|MDB_NOSYNC)))
-                       oflags |= MDB_DSYNC;
-               if ((env->me_mfd = open(dpath, oflags, mode)) == -1) {
-                       rc = ErrCode();
-                       goto leave;
-               }
+                       env->me_mfd = open(dpath, oflags | MDB_DSYNC, mode);
 #endif
+                       if (env->me_mfd == INVALID_HANDLE_VALUE) {
+                               rc = ErrCode();
+                               goto leave;
+                       }
+               }
                env->me_path = strdup(path);
                DPRINTF("opened dbenv %p", (void *) env);
                pthread_key_create(&env->me_txkey, mdb_env_reader_dest);
@@ -3072,7 +3069,8 @@ mdb_env_close(MDB_env *env)
        if (env->me_map) {
                munmap(env->me_map, env->me_mapsize);
        }
-       close(env->me_mfd);
+       if (env->me_mfd != env->me_fd)
+               close(env->me_mfd);
        close(env->me_fd);
        if (env->me_txns) {
                pid_t pid = getpid();