core: refactor timers

- Don't use JS objects for timer handles
- Use a hash table in C rather an a Map in JS
- Allocate memory without using the JS allocator (1)

1) This is important because the libuv loop outlives the JS runtime.
   Since handle closing is not sync and the callback where we need to
   free the structures will be called later it's not safe to use it.
   This is a small step in the direction of not using the JS allocator
   for structures that embed libuv handles.

Author: saghul

src/bundles/c/core/polyfills.c

@@ -1,61 +1,7 @@
 const core = globalThis[Symbol.for('tjs.internal.core')];
 
-const timers = new Map();
-let nextId = 1;
+globalThis.setTimeout = core.setTimeout;
+globalThis.clearTimeout = core.clearTimeout;
 
-function getNextId() {
-    let id;
-
-    // eslint-disable-next-line no-constant-condition
-    while (true) {
-        id = nextId++;
-
-        if (!timers.has(id)) {
-            break;
-        }
-
-        if (nextId >= Number.MAX_SAFE_INTEGER) {
-            nextId = 1;
-        }
-    }
-
-    return id;
-}
-
-globalThis.setTimeout = (fn, ms, ...args) => {
-    const timer = core.setTimeout(fn, ms, ...args);
-    const id = getNextId();
-
-    timers.set(id, timer);
-
-    return id;
-};
-
-globalThis.clearTimeout = id => {
-    const timer = timers.get(id);
-
-    if (timer) {
-        core.clearTimeout(timer);
-    }
-
-    timers.delete(id);
-};
-
-globalThis.setInterval = (fn, ms, ...args) => {
-    const timer = core.setInterval(fn, ms, ...args);
-    const id = getNextId();
-
-    timers.set(id, timer);
-
-    return id;
-};
-
-globalThis.clearInterval = id => {
-    const timer = timers.get(id);
-
-    if (timer) {
-        core.clearInterval(timer);
-    }
-
-    timers.delete(id);
-};
+globalThis.setInterval = core.setInterval;
+globalThis.clearInterval = core.setInterval;

src/js/polyfills/timers.js

@@ -0,0 +1,76 @@
+/*
+ * txiki.js
+ *
+ * Copyright (c) 2024-present Saúl Ibarra Corretgé <s@saghul.net>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef TJS_MEM_H
+#define TJS_MEM_H
+
+#include "../deps/quickjs/cutils.h"
+
+#include <stdlib.h>
+
+#ifdef TJS__HAS_MIMALLOC
+#include <mimalloc.h>
+#endif
+
+static inline size_t tjs__malloc_usable_size(const void *ptr) {
+#if defined(TJS__HAS_MIMALLOC)
+    return mi_malloc_usable_size(ptr);
+#else
+    return js__malloc_usable_size(ptr):
+#endif
+}
+
+static inline void *tjs__malloc(size_t size) {
+#ifdef TJS__HAS_MIMALLOC
+    return mi_malloc(size);
+#else
+    return malloc(size);
+#endif
+}
+
+static inline void *tjs__calloc(size_t count, size_t size) {
+#ifdef TJS__HAS_MIMALLOC
+    return mi_calloc(count, size);
+#else
+    return calloc(count, size);
+#endif
+}
+
+static inline void tjs__free(void *ptr) {
+#ifdef TJS__HAS_MIMALLOC
+    mi_free(ptr);
+#else
+    free(ptr);
+#endif
+}
+
+static inline void *tjs__realloc(void *ptr, size_t size) {
+#ifdef TJS__HAS_MIMALLOC
+    return mi_realloc(ptr, size);
+#else
+    return realloc(ptr, size);
+#endif
+}
+
+#endif

src/mem.h

@@ -34,6 +34,7 @@
 #include <stdbool.h>
 #include <uv.h>
 
+typedef struct TJSTimer TJSTimer;
 
 struct TJSRuntime {
     TJSRunOptions options;
@@ -54,6 +55,10 @@ struct TJSRuntime {
     struct {
         IM3Environment env;
     } wasm_ctx;
+    struct {
+        TJSTimer *timers;
+        int64_t next_timer;
+    } timers;
 };
 
 void tjs__mod_dns_init(JSContext *ctx, JSValue ns);
@@ -96,6 +101,8 @@ JSValue tjs__get_args(JSContext *ctx);
 
 int tjs__eval_bytecode(JSContext *ctx, const uint8_t *buf, size_t buf_len);
 
+void tjs__destroy_timers(TJSRuntime *qrt);
+
 uv_loop_t *TJS_GetLoop(TJSRuntime *qrt);
 TJSRuntime *TJS_NewRuntimeWorker(void);
 TJSRuntime *TJS_NewRuntimeInternal(bool is_worker, TJSRunOptions *options);

src/private.h

@@ -22,22 +22,34 @@
  * THE SOFTWARE.
  */
 
+#include "hash.h"
+#include "mem.h"
 #include "private.h"
 #include "utils.h"
 
+#define MAX_SAFE_INTEGER (((int64_t)1 << 53) - 1)
 
-typedef struct {
+struct TJSTimer {
     JSContext *ctx;
-    JSRuntime *rt;
+    int64_t id;
     uv_timer_t handle;
+    UT_hash_handle hh;
     int interval;
     JSValue func;
     int argc;
     JSValue argv[];
-} TJSTimer;
+};
+
+static void uv__timer_close(uv_handle_t *handle) {
+    TJSTimer *th = handle->data;
+    CHECK_NOT_NULL(th);
+    tjs__free(th);
+}
 
-static void clear_timer(TJSTimer *th) {
+static void destroy_timer(TJSTimer *th) {
     JSContext *ctx = th->ctx;
+    TJSRuntime *qrt = JS_GetContextOpaque(ctx);
+    CHECK_NOT_NULL(qrt);
 
     JS_FreeValue(ctx, th->func);
     th->func = JS_UNDEFINED;
@@ -47,6 +59,18 @@ static void clear_timer(TJSTimer *th) {
         th->argv[i] = JS_UNDEFINED;
     }
     th->argc = 0;
+
+    HASH_DEL(qrt->timers.timers, th);
+
+    uv_close((uv_handle_t *) &th->handle, uv__timer_close);
+}
+
+void tjs__destroy_timers(TJSRuntime *qrt) {
+    TJSTimer *th, *tmp;
+
+    HASH_ITER(hh, qrt->timers.timers, th, tmp) {
+        destroy_timer(th);
+    }
 }
 
 static void call_timer(TJSTimer *th) {
@@ -61,12 +85,6 @@ static void call_timer(TJSTimer *th) {
     JS_FreeValue(ctx, ret);
 }
 
-static void uv__timer_close(uv_handle_t *handle) {
-    TJSTimer *th = handle->data;
-    CHECK_NOT_NULL(th);
-    js_free_rt(th->rt, th);
-}
-
 static void uv__timer_cb(uv_timer_t *handle) {
     TJSTimer *th = handle->data;
     CHECK_NOT_NULL(th);
@@ -75,71 +93,43 @@ static void uv__timer_cb(uv_timer_t *handle) {
     tjs__execute_jobs(th->ctx);
 
     call_timer(th);
-    if (!th->interval)
-        clear_timer(th);
-}
-
-static JSClassID tjs_timer_class_id;
 
-static void tjs_timer_finalizer(JSRuntime *rt, JSValue val) {
-    TJSTimer *th = JS_GetOpaque(val, tjs_timer_class_id);
-    if (th) {
-        clear_timer(th);
-        /* The handle might have been closed by the loop destruction in TJS_FreeRuntime. */
-        if (!uv_is_closing((uv_handle_t *) &th->handle))
-            uv_close((uv_handle_t *) &th->handle, uv__timer_close);
-    }
-}
-
-static void tjs_timer_mark(JSRuntime *rt, JSValueConst val, JS_MarkFunc *mark_func) {
-    TJSTimer *th = JS_GetOpaque(val, tjs_timer_class_id);
-    if (th) {
-        JS_MarkValue(rt, th->func, mark_func);
-        for (int i = 0; i < th->argc; i++)
-            JS_MarkValue(rt, th->argv[i], mark_func);
-    }
+    if (!th->interval)
+        destroy_timer(th);
 }
 
-static JSClassDef tjs_timer_class = {
-    "Timer",
-    .finalizer = tjs_timer_finalizer,
-    .gc_mark = tjs_timer_mark,
-};
+static JSValue tjs_setTimeout(JSContext *ctx, JSValue this_val, int argc, JSValue *argv, int magic) {
+    TJSRuntime *qrt = JS_GetContextOpaque(ctx);
+    CHECK_NOT_NULL(qrt);
 
-static JSValue tjs_setTimeout(JSContext *ctx, JSValueConst this_val, int argc, JSValueConst *argv, int magic) {
     int64_t delay;
-    JSValueConst func;
+    JSValue func;
     TJSTimer *th;
-    JSValue obj;
 
     func = argv[0];
     if (!JS_IsFunction(ctx, func))
         return JS_ThrowTypeError(ctx, "not a function");
 
     if (argc <= 1) {
         delay = 0;
-    } else {
-        if (JS_ToInt64(ctx, &delay, argv[1]))
-            return JS_EXCEPTION;
+    } else if (JS_ToInt64(ctx, &delay, argv[1])) {
+        return JS_EXCEPTION;
     }
 
-    obj = JS_NewObjectClass(ctx, tjs_timer_class_id);
-    if (JS_IsException(obj))
-        return obj;
-
     int nargs = argc - 2;
     if (nargs < 0) {
         nargs = 0;
     }
 
-    th = js_mallocz(ctx, sizeof(*th) + nargs * sizeof(JSValue));
-    if (!th) {
-        JS_FreeValue(ctx, obj);
-        return JS_EXCEPTION;
-    }
+    th = tjs__malloc(sizeof(*th) + nargs * sizeof(JSValue));
+    if (!th)
+        return JS_ThrowOutOfMemory(ctx);
+
+    th->id = qrt->timers.next_timer++;
+    if (qrt->timers.next_timer > MAX_SAFE_INTEGER)
+        qrt->timers.next_timer = 1;
 
     th->ctx = ctx;
-    th->rt = JS_GetRuntime(ctx);
     CHECK_EQ(uv_timer_init(tjs_get_loop(ctx), &th->handle), 0);
     th->handle.data = th;
     th->interval = magic;
@@ -150,17 +140,26 @@ static JSValue tjs_setTimeout(JSContext *ctx, JSValueConst this_val, int argc, J
 
     CHECK_EQ(uv_timer_start(&th->handle, uv__timer_cb, delay, magic ? delay : 0 /* repeat */), 0);
 
-    JS_SetOpaque(obj, th);
-    return obj;
+    HASH_ADD_INT64(qrt->timers.timers, id, th);
+
+    return JS_NewInt64(ctx, th->id);
 }
 
-static JSValue tjs_clearTimeout(JSContext *ctx, JSValueConst this_val, int argc, JSValueConst *argv) {
-    TJSTimer *th = JS_GetOpaque2(ctx, argv[0], tjs_timer_class_id);
-    if (!th)
+static JSValue tjs_clearTimeout(JSContext *ctx, JSValue this_val, int argc, JSValue *argv) {
+    TJSRuntime *qrt = JS_GetContextOpaque(ctx);
+    CHECK_NOT_NULL(qrt);
+    int64_t timer_id;
+    TJSTimer *th = NULL;
+
+    if (JS_ToInt64(ctx, &timer_id, argv[0]))
         return JS_EXCEPTION;
 
-    CHECK_EQ(uv_timer_stop(&th->handle), 0);
-    clear_timer(th);
+    HASH_FIND_INT64(qrt->timers.timers, &timer_id, th);
+
+    if (th != NULL) {
+        CHECK_EQ(uv_timer_stop(&th->handle), 0);
+        destroy_timer(th);
+    }
 
     return JS_UNDEFINED;
 }
@@ -171,9 +170,5 @@ static const JSCFunctionListEntry tjs_timer_funcs[] = { JS_CFUNC_MAGIC_DEF("setT
                                                         TJS_CFUNC_DEF("clearInterval", 1, tjs_clearTimeout) };
 
 void tjs__mod_timers_init(JSContext *ctx, JSValue ns) {
-    JSRuntime *rt = JS_GetRuntime(ctx);
-
-    JS_NewClassID(rt, &tjs_timer_class_id);
-    JS_NewClass(rt, tjs_timer_class_id, &tjs_timer_class);
     JS_SetPropertyFunctionList(ctx, ns, tjs_timer_funcs, countof(tjs_timer_funcs));
 }