return previous GC state for gc_enable/gc_disable

NEWS.md

@@ -111,6 +111,8 @@ Library improvements
 
  * Other improvements
 
+ * `gc_enable`, `gc_disable` returns previous GC state.
+
  * `assert`, `@assert` now throws an `AssertionError` exception type ([#9734]).
 
  * `convert` now checks for overflow when truncating integers or converting between

base/base.jl

@@ -162,9 +162,9 @@ end
 
 finalize(o::ANY) = ccall(:jl_finalize, Void, (Any,), o)
 
-gc(full = true) = ccall(:jl_gc_collect, Void, (Int,), full ? 1 : 0)
-gc_enable() = ccall(:jl_gc_enable, Void, ())
-gc_disable() = ccall(:jl_gc_disable, Void, ())
+gc(full::Bool=true) = ccall(:jl_gc_collect, Void, (Cint,), full)
+gc_enable() = bool(ccall(:jl_gc_enable, Cint, ()))
+gc_disable() = bool(ccall(:jl_gc_disable, Cint, ()))
 
 bytestring(str::ByteString) = str
 

doc/stdlib/base.rst

@@ -955,10 +955,11 @@ Internals
 
  Disable garbage collection. This should be used only with extreme
  caution, as it can cause memory use to grow without bound.
+ Returns previous GC state.
 
 .. function:: gc_enable()
 
- Re-enable garbage collection after calling :func:`gc_disable`.
+ Re-enable garbage collection after calling :func:`gc_disable`. Returns previous GC state.
 
 .. function:: macroexpand(x)
 

src/gc.c

@@ -1948,8 +1948,18 @@ static void gc_verify(void)
 // collector entry point and control
 
 static int is_gc_enabled = 1;
-DLLEXPORT void jl_gc_enable(void) { is_gc_enabled = 1; }
-DLLEXPORT void jl_gc_disable(void) { is_gc_enabled = 0; }
+DLLEXPORT int jl_gc_enable(void)
+{
+ int prev = is_gc_enabled;
+ is_gc_enabled = 1;
+ return prev;
+}
+DLLEXPORT int jl_gc_disable(void)
+{
+ int prev = is_gc_enabled;
+ is_gc_enabled = 0;
+ return prev;
+}
 DLLEXPORT int jl_gc_is_enabled(void) { return is_gc_enabled; }
 
 DLLEXPORT int64_t jl_gc_total_bytes(void) { return total_allocd_bytes + allocd_bytes + collect_interval; }

src/julia.h

@@ -1132,8 +1132,8 @@ extern DLLEXPORT jl_gcframe_t *jl_pgcstack;
 
 void jl_gc_init(void);
 void jl_gc_setmark(jl_value_t *v);
-DLLEXPORT void jl_gc_enable(void);
-DLLEXPORT void jl_gc_disable(void);
+DLLEXPORT int jl_gc_enable(void);
+DLLEXPORT int jl_gc_disable(void);
 DLLEXPORT int jl_gc_is_enabled(void);
 DLLEXPORT int64_t jl_gc_total_bytes(void);
 DLLEXPORT uint64_t jl_gc_total_hrtime(void);

test/misc.jl

@@ -113,3 +113,11 @@ let # test the process title functions, issue #9957
  Sys.set_process_title(oldtitle)
  @test Sys.get_process_title() == oldtitle
 end
+
+
+# test gc_enable/disable
+@test gc_enable()
+@test gc_disable()
+@test gc_disable() == false
+@test gc_enable() == false
+@test gc_enable()