Fixed a few mistakes.

c_src/wterl.c

@@ -46,8 +46,8 @@ struct wterl_ctx {
     uint64_t sig;
     size_t sig_len;
     WT_SESSION *session;
-    const char *session_config;
     uint32_t num_cursors;
+    const char *session_config;
     struct cursor_info {
         const char *uri;
         const char *config;
@@ -191,13 +191,16 @@ static inline uint32_t __log2(uint64_t x) {
 static int
 __ctx_cache_evict(WterlConnHandle *conn_handle)
 {
-    uint32_t mean, log, num_evicted, i;
+    uint32_t num_evicted = 0;
-    uint64_t now, elapsed;
+    struct wterl_ctx *c;
-    struct wterl_ctx *c, *n;
 
     if (conn_handle->cache_size < MAX_CACHE_SIZE)
         return 0;
 
+#if 0 // TODO: fixme once stats work again
+    uint32_t mean, log, num_evicted, i;
+    uint64_t now, elapsed;
+    struct wterl_ctx *c, *n;
     now = cpu_clock_ticks();
 
     // Find the mean of the recorded times that items stayed in cache.
@@ -230,6 +233,16 @@ __ctx_cache_evict(WterlConnHandle *conn_handle)
         }
         c = n;
     }
+#else
+    c = STAILQ_FIRST(&conn_handle->cache);
+    if (c) {
+        STAILQ_REMOVE(&conn_handle->cache, c, wterl_ctx, entries);
+        DPRINTF("evicting: %llu", PRIuint64(c->sig));
+        c->session->close(c->session, NULL);
+        enif_free(c);
+        num_evicted++;
+    }
+#endif
     conn_handle->cache_size -= num_evicted;
     return num_evicted;
 }
@@ -246,22 +259,20 @@ __ctx_cache_evict(WterlConnHandle *conn_handle)
 static struct wterl_ctx *
 __ctx_cache_find(WterlConnHandle *conn_handle, const uint64_t sig)
 {
-    struct wterl_ctx *c, *n;
+    struct wterl_ctx *c;
 
     enif_mutex_lock(conn_handle->cache_mutex);
     c = STAILQ_FIRST(&conn_handle->cache);
     while (c != NULL) {
-        n = STAILQ_NEXT(c, entries);
         if (c->sig == sig) { // TODO: hash collisions *will* lead to SEGVs
             // cache hit:
-            STAILQ_REMOVE_HEAD(&conn_handle->cache, entries);
+            STAILQ_REMOVE(&conn_handle->cache, c, wterl_ctx, entries);
             conn_handle->histogram[__log2(cpu_clock_ticks() - c->tstamp)]++;
             conn_handle->histogram_count++;
             conn_handle->cache_size -= 1;
             break;
-        } else {
-            c = n;
         }
+        c = STAILQ_NEXT(c, entries);
     }
     enif_mutex_unlock(conn_handle->cache_mutex);
     return c;
@@ -369,7 +380,6 @@ __retain_ctx(WterlConnHandle *conn_handle, uint32_t worker_id,
 
     *ctx = NULL;
     do {
-	WMB_NEAR_CAS();
         c = conn_handle->mru_ctx[worker_id];
         if (CASPO(&conn_handle->mru_ctx[worker_id], c, 0) == c) {
             if (c == 0) {
@@ -457,7 +467,6 @@ __release_ctx(WterlConnHandle *conn_handle, uint32_t worker_id, struct wterl_ctx
         cursor->reset(cursor);
     }
 
-    WMB_NEAR_CAS();
     c = conn_handle->mru_ctx[worker_id];
     if (CASPO(&conn_handle->mru_ctx[worker_id], c, ctx) != c) {
         __ctx_cache_add(conn_handle, ctx);
@@ -486,7 +495,6 @@ __close_all_sessions(WterlConnHandle *conn_handle)
     // clear out the mru
     for (worker_id = 0; worker_id < ASYNC_NIF_MAX_WORKERS; worker_id++) {
         do {
-	    WMB_NEAR_CAS();
             c = conn_handle->mru_ctx[worker_id];
         } while(CASPO(&conn_handle->mru_ctx[worker_id], c, 0) != c);
 
@@ -521,7 +529,6 @@ __close_cursors_on(WterlConnHandle *conn_handle, const char *uri)
 
     // walk the mru first, look for open cursors on matching uri
     for (worker_id = 0; worker_id < ASYNC_NIF_MAX_WORKERS; worker_id++) {
-	WMB_NEAR_CAS();
         c = conn_handle->mru_ctx[worker_id];
         if (CASPO(&conn_handle->mru_ctx[worker_id], c, 0) == c && c != 0) {
             cnt = c->num_cursors;
@@ -691,6 +698,7 @@ __strerror_term(ErlNifEnv* env, int rc)
            and/or may be localized to any given language (i18n).  Use the errno
            atom rather than the message when matching in Erlang.  You've been
            warned. */
+        DPRINTF("error: %s", erl_errno_id(rc));
         return enif_make_tuple2(env, ATOM_ERROR,
                     enif_make_tuple2(env,
                          enif_make_atom(env, erl_errno_id(rc)),
@@ -1861,6 +1869,7 @@ ASYNC_NIF_DECL(
 
     WT_CURSOR* cursor = args->cursor_handle->cursor;
     ASYNC_NIF_REPLY(__cursor_value_ret(env, cursor, cursor->next(cursor)));
+    DPRINTF("env: %p cursor: %p", env, cursor);
   },
   { // post
 

src/riak_kv_wterl_backend.erl

@@ -52,9 +52,7 @@
 
 -record(state, {table :: string(),
                 type :: string(),
-                connection :: wterl:connection(),
+                connection :: wterl:connection()}).
-                is_empty_cursor :: wterl:cursor(),
-                status_cursor :: wterl:cursor()}).
 
 -type state() :: #state{}.
 -type config() :: [{atom(), term()}].
@@ -135,15 +133,8 @@ start(Partition, Config) ->
                 end,
             case wterl:create(Connection, Table, TableOpts) of
                 ok ->
-                    case establish_utility_cursors(Connection, Table) of
-                        {ok, IsEmptyCursor, StatusCursor} ->
 		    {ok, #state{table=Table, type=Type,
-                                        connection=Connection,
+				connection=Connection}};
-                                        is_empty_cursor=IsEmptyCursor,
-                                        status_cursor=StatusCursor}};
-                        {error, Reason2} ->
-                            {error, Reason2}
-                    end;
                 {error, Reason3} ->
                     {error, Reason3}
                 end
@@ -329,18 +320,30 @@ drop(#state{connection=Connection, table=Table}=State) ->
 %% @doc Returns true if this wterl backend contains any
 %% non-tombstone values; otherwise returns false.
 -spec is_empty(state()) -> boolean().
-is_empty(#state{is_empty_cursor=Cursor}) ->
+is_empty(#state{connection=Connection, table=Table}) ->
-    wterl:cursor_reset(Cursor),
+    case wterl:cursor_open(Connection, Table) of
+        {ok, Cursor} ->
+	    IsEmpty =
 		case wterl:cursor_next(Cursor) of
-        not_found -> true;
+		    not_found ->
-        {error, {eperm, _}} -> false; % TODO: review/fix this logic
+			true;
-        _ -> false
+		    {error, {eperm, _}} ->
+			false; % TODO: review/fix this logic
+		    _ ->
+			false
+		end,
+	    wterl:cursor_close(Cursor),
+	    IsEmpty;
+        {error, Reason2} ->
+            {error, Reason2}
     end.
 
 %% @doc Get the status information for this wterl backend
 -spec status(state()) -> [{atom(), term()}].
-status(#state{status_cursor=Cursor}) ->
+status(#state{connection=Connection, table=Table}) ->
-    wterl:cursor_reset(Cursor),
+    case wterl:cursor_open(Connection, Table) of
+        {ok, Cursor} ->
+	    TheStats =
 		case fetch_status(Cursor) of
 		    {ok, Stats} ->
 			Stats;
@@ -348,6 +351,11 @@ status(#state{status_cursor=Cursor}) ->
 			{ok, []};
 		    _ ->
 			{ok, []}
+		end,
+	    wterl:cursor_close(Cursor),
+	    TheStats;
+        {error, Reason2} ->
+            {error, Reason2}
     end.
 
 %% @doc Register an asynchronous callback
@@ -373,20 +381,6 @@ max_sessions(Config) ->
         false -> Est
     end.
 
-%% @private
-establish_utility_cursors(Connection, Table) ->
-    case wterl:cursor_open(Connection, Table) of
-        {ok, IsEmptyCursor} ->
-            case wterl:cursor_open(Connection, "statistics:" ++ Table, [{statistics_fast, true}]) of
-                {ok, StatusCursor} ->
-                    {ok, IsEmptyCursor, StatusCursor};
-                {error, Reason1} ->
-                    {error, Reason1}
-            end;
-        {error, Reason2} ->
-            {error, Reason2}
-    end.
-
 %% @private
 establish_connection(Config, Type) ->
     %% Get the data root directory

src/wterl.erl

@@ -95,6 +95,7 @@ nif_stub_error(Line) ->
 
 -spec init() -> ok | {error, any()}.
 init() ->
+    Module <- [wterl, wterl_conn, wterl_app, wterl_sup, wterl_ets, riak_kv_wiredtiger_backend, temp_riak_kv_backend]],
     erlang:load_nif(filename:join([priv_dir(), atom_to_list(?MODULE)]),
            [{wterl_vsn, "53307e8"},
 	    {wiredtiger_vsn, "1.6.2-0-g07cb0a5"}]).