QuickJS: discard contexts with pending jobs

A job exception stops the teardown drain immediately.  Jobs left behind
could then run after the context was bound to another request.  Releasing
events and root values after the drain could also enqueue new jobs with
the same result.

Treat a successful, complete job drain as a precondition for context
reuse.  Destroy the runtime when the drain fails or the queue becomes
nonempty during the remaining teardown.

diff --git a/nginx/ngx_js.c b/nginx/ngx_js.c
index f18acb6ab6d1549cf272a1dab00c57f8ff167732..1e1ba759ce3ede85c1e334032bf017e315e7b5b0 100644 (file)
--- a/nginx/ngx_js.c
+++ b/nginx/ngx_js.c
@@ -1240,11 +1240,12 @@ void
 ngx_engine_qjs_destroy(ngx_engine_t *e, ngx_js_ctx_t *ctx,
     ngx_js_loc_conf_t *conf)
 {
+    JSValue               ret;
     uint32_t              i, length;
     JSRuntime            *rt;
-    JSValue               ret;
     JSContext            *cx;
     JSClassID             class_id;
+    ngx_uint_t            reusable;
     JSMemoryUsage         stats;
     ngx_qjs_event_t      *event;
     ngx_js_opaque_t      *opaque;
@@ -1253,6 +1254,7 @@ ngx_engine_qjs_destroy(ngx_engine_t *e, ngx_js_ctx_t *ctx,
     ngx_js_code_entry_t  *pc;
 
     cx = e->u.qjs.ctx;
+    reusable = 1;
 
     if (ctx != NULL) {
         ret = qjs_call_exit_hook(cx);
@@ -1260,7 +1262,9 @@ ngx_engine_qjs_destroy(ngx_engine_t *e, ngx_js_ctx_t *ctx,
             ngx_qjs_log_exception(e, ctx->log, "exit hook exception");
         }
 
-        (void) ngx_qjs_execute_pending_jobs(cx, ctx->log);
+        if (ngx_qjs_execute_pending_jobs(cx, ctx->log) != NGX_OK) {
+            reusable = 0;
+        }
 
         node = njs_rbtree_min(&ctx->waiting_events);
 
@@ -1288,6 +1292,13 @@ ngx_engine_qjs_destroy(ngx_engine_t *e, ngx_js_ctx_t *ctx,
         JS_FreeValue(cx, ngx_qjs_arg(ctx->args[0]));
         JS_FreeValue(cx, ngx_qjs_arg(ctx->retval));
 
+        if (JS_IsJobPending(JS_GetRuntime(cx))) {
+            ngx_log_error(NGX_LOG_ERR, ctx->log, 0,
+                          "js pending jobs after context teardown, "
+                          "not reusing context");
+            reusable = 0;
+        }
+
     } else if (e->precompiled != NULL) {
         pc = e->precompiled->start;
         length = e->precompiled->items;
@@ -1299,7 +1310,7 @@ ngx_engine_qjs_destroy(ngx_engine_t *e, ngx_js_ctx_t *ctx,
 
     njs_mp_destroy(e->pool);
 
-    if (conf != NULL && conf->reuse != 0) {
+    if (conf != NULL && conf->reuse != 0 && reusable) {
         if (conf->reuse_queue == NULL) {
             conf->reuse_queue = ngx_js_queue_create(ngx_cycle->pool,
                                                     conf->reuse);