add finalize function to force finalization

ref #7721, #8891

base/base.jl

@@ -147,6 +147,8 @@ function finalizer(o::ANY, f::Union(Function,Ptr))
     ccall(:jl_gc_add_finalizer, Void, (Any,Any), o, f)
 end
 
+finalize(o::ANY) = ccall(:jl_finalize, Void, (Any,), o)
+
 gc() = ccall(:jl_gc_collect, Void, ())
 gc_enable() = ccall(:jl_gc_enable, Void, ())
 gc_disable() = ccall(:jl_gc_disable, Void, ())

base/exports.jl

@@ -1089,6 +1089,7 @@ export
 
 # RTS internals
     finalizer,
+    finalize,
     gc,
     gc_disable,
     gc_enable,

doc/stdlib/base.rst

@@ -217,6 +217,10 @@ All Objects
 
    Register a function ``f(x)`` to be called when there are no program-accessible references to ``x``. The behavior of this function is unpredictable if ``x`` is of a bits type.
 
+.. function:: finalize(x)
+
+   Immediately run finalizers registered for object ``x``.
+
 .. function:: copy(x)
 
    Create a shallow copy of ``x``: the outer structure is copied, but not all internal values. For example, copying an array produces a new array with identically-same elements as the original.

src/gc.c

@@ -274,8 +274,11 @@ static void schedule_finalization(void *o)
 static void run_finalizer(jl_value_t *o, jl_value_t *ff)
 {
     jl_function_t *f;
-    while (jl_is_tuple(ff)) {
-        f = (jl_function_t*)jl_t0(ff);
+    while (1) {
+        if (jl_is_tuple(ff))
+            f = (jl_function_t*)jl_t0(ff);
+        else
+            f = (jl_function_t*)ff;
         assert(jl_is_function(f));
         JL_TRY {
             jl_apply(f, (jl_value_t**)&o, 1);
@@ -285,31 +288,36 @@ static void run_finalizer(jl_value_t *o, jl_value_t *ff)
             jl_static_show(JL_STDERR, jl_exception_in_transit);
             JL_PUTC('\n',JL_STDERR);
         }
-        ff = jl_t1(ff);
-    }
-    f = (jl_function_t*)ff;
-    assert(jl_is_function(f));
-    JL_TRY {
-        jl_apply(f, (jl_value_t**)&o, 1);
+        if (jl_is_tuple(ff))
+            ff = jl_t1(ff);
+        else
+            break;
     }
-    JL_CATCH {
-        JL_PRINTF(JL_STDERR, "error in running finalizer: ");
-        jl_static_show(JL_STDERR, jl_exception_in_transit);
-        JL_PUTC('\n',JL_STDERR);
+}
+
+static int finalize_object(jl_value_t *o)
+{
+    jl_value_t *ff = NULL;
+    int success = 0;
+    JL_GC_PUSH1(&ff);
+    ff = (jl_value_t*)ptrhash_get(&finalizer_table, o);
+    if (ff != HT_NOTFOUND) {
+        ptrhash_remove(&finalizer_table, o);
+        run_finalizer((jl_value_t*)o, ff);
+        success = 1;
     }
+    JL_GC_POP();
+    return success;
 }
 
 static void run_finalizers(void)
 {
     void *o = NULL;
-    jl_value_t *ff = NULL;
-    JL_GC_PUSH2(&o, &ff);
+    JL_GC_PUSH1(&o);
     while (to_finalize.len > 0) {
         o = arraylist_pop(&to_finalize);
-        ff = (jl_value_t*)ptrhash_get(&finalizer_table, o);
-        assert(ff != HT_NOTFOUND);
-        ptrhash_remove(&finalizer_table, o);
-        run_finalizer((jl_value_t*)o, ff);
+        int ok = finalize_object(o);
+        assert(ok); (void)ok;
     }
     JL_GC_POP();
 }
@@ -336,6 +344,11 @@ void jl_gc_add_finalizer(jl_value_t *v, jl_function_t *f)
     }
 }
 
+void jl_finalize(jl_value_t *o)
+{
+    (void)finalize_object(o);
+}
+
 // big value list
 
 static bigval_t *big_objects = NULL;

src/julia.h

@@ -1073,6 +1073,7 @@ void jl_gc_preserve(jl_value_t *v);
 void jl_gc_unpreserve(void);
 int jl_gc_n_preserved_values(void);
 DLLEXPORT void jl_gc_add_finalizer(jl_value_t *v, jl_function_t *f);
+DLLEXPORT void jl_finalize(jl_value_t *o);
 DLLEXPORT jl_weakref_t *jl_gc_new_weakref(jl_value_t *value);
 void *jl_gc_managed_malloc(size_t sz);
 void *jl_gc_managed_realloc(void *d, size_t sz, size_t oldsz, int isaligned);

test/core.jl

@@ -549,6 +549,18 @@ begin
     @test glo == 18
 end
 
+# finalizers
+let
+    A = [1]
+    x = 0
+    finalizer(A, a->(x+=1))
+    finalize(A)
+    @test x == 1
+    A = 0
+    gc(); gc()
+    @test x == 1
+end
+
 # issue #7307
 function test7307(a, ret)
     try