feature: added new method "get_stale" to shared dict objects, which returns the value (if not freed yet) even if the key has already expired. thanks Matthieu Tourne for the patch in #249.

src/ngx_http_lua_shdict.c

@@ -18,6 +18,8 @@
 static int ngx_http_lua_shdict_set(lua_State *L);
 static int ngx_http_lua_shdict_safe_set(lua_State *L);
 static int ngx_http_lua_shdict_get(lua_State *L);
+static int ngx_http_lua_shdict_get_stale(lua_State *L);
+static int ngx_http_lua_shdict_get_helper(lua_State *L, int get_stale);
 static int ngx_http_lua_shdict_expire(ngx_http_lua_shdict_ctx_t *ctx,
     ngx_uint_t n);
 static ngx_int_t ngx_http_lua_shdict_lookup(ngx_shm_zone_t *shm_zone,
@@ -291,11 +293,14 @@ ngx_http_lua_inject_shdict_api(ngx_http_lua_main_conf_t *lmcf, lua_State *L)
         lua_createtable(L, 0, lmcf->shm_zones->nelts /* nrec */);
                 /* ngx.shared */
 
-        lua_createtable(L, 0 /* narr */, 12 /* nrec */); /* shared mt */
+        lua_createtable(L, 0 /* narr */, 13 /* nrec */); /* shared mt */
 
         lua_pushcfunction(L, ngx_http_lua_shdict_get);
         lua_setfield(L, -2, "get");
 
+        lua_pushcfunction(L, ngx_http_lua_shdict_get_stale);
+        lua_setfield(L, -2, "get_stale");
+
         lua_pushcfunction(L, ngx_http_lua_shdict_set);
         lua_setfield(L, -2, "set");
 
@@ -355,6 +360,20 @@ ngx_http_lua_inject_shdict_api(ngx_http_lua_main_conf_t *lmcf, lua_State *L)
 
 static int
 ngx_http_lua_shdict_get(lua_State *L)
+{
+  return ngx_http_lua_shdict_get_helper(L, 0 /* stale */);
+}
+
+
+static int
+ngx_http_lua_shdict_get_stale(lua_State *L)
+{
+  return ngx_http_lua_shdict_get_helper(L, 1 /* stale */);
+}
+
+
+static int
+ngx_http_lua_shdict_get_helper(lua_State *L, int get_stale)
 {
     int                          n;
     ngx_str_t                    name;
@@ -411,20 +430,22 @@ ngx_http_lua_shdict_get(lua_State *L)
     ngx_shmtx_lock(&ctx->shpool->mutex);
 
 #if 1
-    ngx_http_lua_shdict_expire(ctx, 1);
+    if (!get_stale) {
+        ngx_http_lua_shdict_expire(ctx, 1);
+    }
 #endif
 
     rc = ngx_http_lua_shdict_lookup(zone, hash, key.data, key.len, &sd);
 
     dd("shdict lookup returns %d", (int) rc);
 
-    if (rc == NGX_DECLINED || rc == NGX_DONE) {
+    if (rc == NGX_DECLINED || (rc == NGX_DONE && !get_stale)) {
         ngx_shmtx_unlock(&ctx->shpool->mutex);
         lua_pushnil(L);
         return 1;
     }
 
-    /* rc == NGX_OK */
+    /* rc == NGX_OK || (rc == NGX_DONE && get_stale) */
 
     value_type = sd->value_type;
 
@@ -485,6 +506,21 @@ ngx_http_lua_shdict_get(lua_State *L)
 
     ngx_shmtx_unlock(&ctx->shpool->mutex);
 
+    if (get_stale) {
+
+        /* always return value, flags, stale */
+
+        if (user_flags) {
+            lua_pushinteger(L, (lua_Integer) user_flags);
+
+        } else {
+            lua_pushnil(L);
+        }
+
+        lua_pushboolean(L, rc == NGX_DONE);
+        return 3;
+    }
+
     if (user_flags) {
         lua_pushinteger(L, (lua_Integer) user_flags);
         return 2;

t/043-shdict.t

@@ -1452,3 +1452,26 @@ cur value:  hello hello hello hello hello hello hello hello hello hello1
 --- no_error_log
 [error]
 
+
+
+=== TEST 60: get_stale: expired entries can still be fetched
+--- http_config
+    lua_shared_dict dogs 1m;
+--- config
+    location = /test {
+        content_by_lua '
+            local dogs = ngx.shared.dogs
+            dogs:set("foo", 32, 0.01)
+            dogs:set("blah", 33, 0.1)
+            ngx.sleep(0.01)
+            local val, flags, stale = dogs:get_stale("foo")
+            ngx.say(val, ", ", flags, ", ", stale)
+            local val, flags, stale = dogs:get_stale("blah")
+            ngx.say(val, ", ", flags, ", ", stale)
+        ';
+    }
+--- request
+GET /test
+--- response_body
+32, nil, true
+33, nil, false

t/062-count.t

@@ -279,7 +279,7 @@ n = 4
 --- request
 GET /test
 --- response_body
-n = 12
+n = 13
 --- no_error_log
 [error]