Introduced module compatibility vector.

src/nxt_application.c

@@ -37,6 +37,11 @@ static nxt_http_fields_hash_t        *nxt_app_request_fields_hash;
 static nxt_application_module_t      *nxt_app;
 
 
+static uint32_t  compat[] = {
+    NXT_VERNUM,
+};
+
+
 nxt_int_t
 nxt_discovery_start(nxt_task_t *task, void *data)
 {
@@ -195,18 +200,29 @@ nxt_discovery_module(nxt_task_t *task, nxt_mp_t *mp, nxt_array_t *modules,
     app = dlsym(dl, "nxt_app_module");
 
     if (app != NULL) {
-        nxt_log(task, NXT_LOG_NOTICE, "module: %V \"%s\"",
+        nxt_log(task, NXT_LOG_NOTICE, "module: %V %V \"%s\"",
-                &app->version, name);
+                &app->type, &app->version, name);
+
+        if (app->compat_length != sizeof(compat)
+            || nxt_memcmp(app->compat, compat, sizeof(compat)) != 0)
+        {
+            nxt_log(task, NXT_LOG_NOTICE, "incompatible module %s", name);
+
+            goto done;
+        }
 
         module = modules->elts;
         n = modules->nelts;
 
         for (i = 0; i < n; i++) {
-            if (nxt_strstr_eq(&app->version, &module[i].version)) {
+            if (nxt_strstr_eq(&app->type, &module[i].type)
+                && nxt_strstr_eq(&app->version, &module[i].version))
+            {
                 nxt_log(task, NXT_LOG_NOTICE,
                         "ignoring %s module with the same "
-                        "application language version %V as in %s",
+                        "application language version %V %V as in %s",
-                        name, &module[i].version, &module[i].file);
+                        name, &module[i].type, &module[i].version,
+                        &module[i].file);
 
                 goto done;
             }

src/nxt_application.h

@@ -203,6 +203,9 @@ NXT_EXPORT nxt_int_t nxt_app_msg_read_size(nxt_task_t *task,
 
 
 struct nxt_app_module_s {
+    size_t                     compat_length;
+    uint32_t                   *compat;
+
     nxt_str_t                  type;
     nxt_str_t                  version;
 

src/nxt_go.c

@@ -14,6 +14,8 @@ static nxt_int_t nxt_go_run(nxt_task_t *task,
                       nxt_app_rmsg_t *rmsg, nxt_app_wmsg_t *msg);
 
 nxt_application_module_t  nxt_go_module = {
+    0,
+    NULL,
     nxt_string("go"),
     nxt_string("go"),
     nxt_go_init,

src/nxt_main.h

@@ -12,6 +12,7 @@
 
 
 #define NXT_VERSION                  "0.1"
+#define NXT_VERNUM                   0x00000001
 
 
 typedef struct nxt_port_s            nxt_port_t;

src/nxt_main_process.c

@@ -1026,6 +1026,16 @@ nxt_app_lang_compare(const void *v1, const void *v2)
     lang1 = v1;
     lang2 = v2;
 
+    if (lang1->type.length != lang2->type.length) {
+        return lang1->type.length - lang2->type.length;
+    }
+
+    n = nxt_strncmp(lang1->type.start, lang2->type.start, lang1->type.length);
+
+    if (n != 0) {
+        return n;
+    }
+
     length = nxt_min(lang1->version.length, lang2->version.length);
 
     n = nxt_strncmp(lang1->version.start, lang2->version.start, length);

src/nxt_php_sapi.c

@@ -167,8 +167,14 @@ nxt_php_str_trim_lead(nxt_str_t *str, u_char t)
     }
 }
 
+static uint32_t  compat[] = {
+    NXT_VERNUM,
+};
+
 
 NXT_EXPORT nxt_application_module_t  nxt_app_module = {
+    sizeof(compat),
+    compat,
     nxt_string("php"),
     nxt_string(PHP_VERSION),
     nxt_php_init,

src/nxt_python_wsgi.c

@@ -91,7 +91,14 @@ nxt_inline nxt_int_t nxt_python_write_py_str(nxt_python_run_ctx_t *ctx,
                       PyObject *str, nxt_bool_t flush, nxt_bool_t last);
 
 
+static uint32_t  compat[] = {
+    NXT_VERNUM,
+};
+
+
 NXT_EXPORT nxt_application_module_t  nxt_app_module = {
+    sizeof(compat),
+    compat,
     nxt_string("python"),
     nxt_string(PY_VERSION),
     nxt_python_init,