zend_async_API: drop dead key_name lookup; trim comments

zend_async_internal_context_key_name had no callers anywhere in the tree.
The key registry is written only at MINIT, so the read-side lock added
earlier was unnecessary and is gone with the function.

Author: EdmondDantes

Zend/zend_async_API.c

@@ -110,22 +110,6 @@ ZEND_API uint32_t zend_async_internal_context_key_alloc(const char *key_name)
 	return key;
 }
 
-ZEND_API const char *zend_async_internal_context_key_name(uint32_t key)
-{
-	/* A non-NULL table implies the mutex exists: key_alloc creates the mutex
-	 * before the table. The lock shields the read from a concurrent alloc
-	 * rehashing the bucket array. */
-	if (internal_context_key_names == NULL) {
-		return NULL;
-	}
-
-	tsrm_mutex_lock(internal_context_mutex);
-	const char *name = zend_hash_index_find_ptr(internal_context_key_names, key);
-	tsrm_mutex_unlock(internal_context_mutex);
-
-	return name;
-}
-
 static void internal_context_keys_shutdown(void)
 {
 	if (internal_context_key_names != NULL) {

Zend/zend_async_API.h

@@ -476,7 +476,6 @@ ZEND_API const char *zend_async_get_scheduler_module(void);
  * one. Values may hold raw C data, so the store is structurally
  * unreachable from PHP. */
 ZEND_API uint32_t zend_async_internal_context_key_alloc(const char *key_name);
-ZEND_API const char *zend_async_internal_context_key_name(uint32_t key);
 ZEND_API zval *zend_async_internal_context_find(zend_coroutine_t *coroutine, uint32_t key);
 ZEND_API bool zend_async_internal_context_set(
 		zend_coroutine_t *coroutine, uint32_t key, zval *value);

ext/async_scheduler_hook/async_scheduler_hook.c

@@ -238,9 +238,7 @@ typedef struct {
 
 /* Wrapped handler tables, one per original table (i.e. per coroutine
  * class). Process-lifetime: objects carrying a wrapper may outlive any
- * request-local storage. Shared by every thread — mutate under the mutex
- * (the same original table, std_object_handlers say, is hit from all of
- * them). */
+ * request-local storage. */
 static HashTable *php_async_wrapped_handlers = NULL;
 static MUTEX_T php_async_wrapped_handlers_mutex = NULL;
 
@@ -324,9 +322,7 @@ static void php_async_coroutine_object_free(zend_object *object)
 	wrapper->original->free_obj(object);
 }
 
-/* get_gc for a wrapped coroutine object: the handle owns references (the
- * bound entry, results, errors, the context) invisible to the class's own
- * get_gc — a cycle through them would never collect. */
+/* The handle owns references the class's own get_gc cannot see. */
 static HashTable *php_async_coroutine_object_gc(zend_object *object, zval **table, int *num)
 {
 	const php_async_handlers_wrapper_t *wrapper =
@@ -345,9 +341,8 @@ static HashTable *php_async_coroutine_object_gc(zend_object *object, zval **tabl
 		return ht;
 	}
 
-	/* Original first, buffer second: if the original itself used the shared
-	 * gc buffer, copying entry i over slot <= i is harmless, and the handle's
-	 * entries only append after every original entry was read. */
+	/* The original may have used this same shared buffer: create() resets it,
+	 * and copying entry i over slot <= i is safe. */
 	zend_get_gc_buffer *buf = zend_get_gc_buffer_create();
 
 	for (int i = 0; i < orig_num; i++) {
@@ -382,8 +377,7 @@ static HashTable *php_async_coroutine_object_gc(zend_object *object, zval **tabl
 		}
 	}
 
-	/* The embedded internal-context table is not a collectable array itself —
-	 * report its values, not the table. */
+	/* Embedded, not a collectable array: report the values, not the table. */
 	zval *zv;
 	ZEND_HASH_FOREACH_VAL(&handle->coro.internal_context, zv) {
 		zend_get_gc_buffer_add_zval(buf, zv);
@@ -491,8 +485,7 @@ static void php_async_record_current(bool ok, zval *retval)
 static zend_function php_async_root_function = { ZEND_INTERNAL_FUNCTION };
 
 /* Set by the switcher before a first entry: a fresh context has no other way
- * to reach its handle. Thread-local: the write and the first-entry read must
- * stay on the same thread. */
+ * to reach its handle. */
 ZEND_TLS php_coroutine_t *php_async_starting = NULL;
 
 /* First-run trampoline: install a VM stack, run the body, return to the last
@@ -707,8 +700,7 @@ static ZEND_NAMED_FUNCTION(php_async_mandate_switch_to)
 		RETURN_THROWS();
 	}
 
-	/* The engine-level assert for this is a no-op in release builds, and a
-	 * to == from switch corrupts the context machinery. */
+	/* The engine only asserts to != from, and asserts are no-ops in release. */
 	if (UNEXPECTED(handle->ctx == EG(current_fiber_context))) {
 		zend_throw_error(NULL, "Cannot switch into the currently running coroutine");
 		RETURN_THROWS();