Merge pull request #1924 from MartinNowak/open_gc_registry

implement open GC registry
merged-on-behalf-of: unknown

Author: The Dlang Bot

changelog/gc_registry.dd

@@ -0,0 +1,7 @@
+User supplied garbage collectors can now be linked with the runtime
+
+A GC registry has been implemented that allows to add
+garbage collector implementations by just linking them into
+the binary.  See the
+$(LINK2 $(ROOT_DIR)spec/garbage.html#gc_registry, documentation)
+for details.

mak/SRCS

@@ -390,10 +390,11 @@ SRCS=\
 	src\gc\bits.d \
 	src\gc\config.d \
 	src\gc\gcinterface.d \
+	src\gc\impl\conservative\gc.d \
 	src\gc\os.d \
 	src\gc\pooltable.d \
 	src\gc\proxy.d \
-	src\gc\impl\conservative\gc.d \
+	src\gc\registry.d \
 	src\gc\impl\manual\gc.d \
 	src\gc\impl\proto\gc.d \
 	\

src/gc/config.d

@@ -34,19 +34,27 @@ struct Config
 
     void help() @nogc nothrow
     {
-        string s = "GC options are specified as whitespace separated assignments:
+        import gc.registry : registeredGCFactories;
+
+        printf("GC options are specified as white space separated assignments:
     disable:0|1    - start disabled (%d)
     profile:0|1|2  - enable profiling with summary when terminating program (%d)
-    gc:conservative|precise|manual - select gc implementation (default = conservative)
+    gc:".ptr, disable, profile);
+        foreach (i, entry; registeredGCFactories)
+        {
+            if (i) printf("|");
+            printf("%.*s", cast(int) entry.name.length, entry.name.ptr);
+        }
+        printf(" - select gc implementation (default = conservative)
 
     initReserve:N  - initial memory to reserve in MB (%lld)
     minPoolSize:N  - initial and minimum pool size in MB (%lld)
     maxPoolSize:N  - maximum pool size in MB (%lld)
     incPoolSize:N  - pool size increment MB (%lld)
     heapSizeFactor:N - targeted heap size to used memory ratio (%g)
     cleanup:none|collect|finalize - how to treat live objects when terminating (collect)
-";
-        printf(s.ptr, disable, profile, cast(long)initReserve, cast(long)minPoolSize,
+".ptr,
+               cast(long)initReserve, cast(long)minPoolSize,
                cast(long)maxPoolSize, cast(long)incPoolSize, heapSizeFactor);
     }
 

src/gc/gcinterface.d

@@ -38,12 +38,6 @@ struct Range
 
 interface GC
 {
-
-    /*
-     *
-     */
-    void Dtor();
-
     /**
      *
      */

src/gc/impl/conservative/gc.d

@@ -103,6 +103,42 @@ alias GC gc_t;
 
 /* ============================ GC =============================== */
 
+// register GC in C constructor (_STI_)
+extern(C) pragma(crt_constructor) void _d_register_conservative_gc()
+{
+    import gc.registry;
+    registerGCFactory("conservative", &initialize);
+}
+
+extern(C) pragma(crt_constructor) void _d_register_precise_gc()
+{
+    import gc.registry;
+    registerGCFactory("precise", &initialize_precise);
+}
+
+private GC initialize()
+{
+    import core.stdc.string: memcpy;
+
+    auto p = cstdlib.malloc(__traits(classInstanceSize, ConservativeGC));
+
+    if (!p)
+        onOutOfMemoryErrorNoGC();
+
+    auto init = typeid(ConservativeGC).initializer();
+    assert(init.length == __traits(classInstanceSize, ConservativeGC));
+    auto instance = cast(ConservativeGC) memcpy(p, init.ptr, init.length);
+    instance.__ctor();
+
+    return instance;
+}
+
+private GC initialize_precise()
+{
+    ConservativeGC.isPrecise = true;
+    return initialize();
+}
+
 class ConservativeGC : GC
 {
     // For passing to debug code (not thread safe)
@@ -124,42 +160,6 @@ class ConservativeGC : GC
         gcLock.lock();
     }
 
-
-    static void initialize(ref GC gc)
-    {
-        import core.stdc.string: memcpy;
-
-        if ((config.gc != "precise") && (config.gc != "conservative"))
-            return;
-
-        if (config.gc == "precise")
-            isPrecise = true;
-
-        auto p = cstdlib.malloc(__traits(classInstanceSize,ConservativeGC));
-
-        if (!p)
-            onOutOfMemoryErrorNoGC();
-
-        auto init = typeid(ConservativeGC).initializer();
-        assert(init.length == __traits(classInstanceSize, ConservativeGC));
-        auto instance = cast(ConservativeGC) memcpy(p, init.ptr, init.length);
-        instance.__ctor();
-
-        gc = instance;
-    }
-
-
-    static void finalize(ref GC gc)
-    {
-        if ((config.gc != "precise") && (config.gc != "conservative"))
-            return;
-
-        auto instance = cast(ConservativeGC) gc;
-        instance.Dtor();
-        cstdlib.free(cast(void*)instance);
-    }
-
-
     this()
     {
         //config is assumed to have already been initialized
@@ -176,7 +176,7 @@ class ConservativeGC : GC
     }
 
 
-    void Dtor()
+    ~this()
     {
         version (linux)
         {
@@ -190,6 +190,9 @@ class ConservativeGC : GC
             cstdlib.free(gcx);
             gcx = null;
         }
+        // TODO: cannot free as memory is overwritten and
+        //  the monitor is still read in rt_finalize (called by destroy)
+        // cstdlib.free(cast(void*) this);
     }
 
 

src/gc/impl/manual/gc.d

@@ -35,46 +35,43 @@ static import core.memory;
 
 extern (C) void onOutOfMemoryError(void* pretend_sideffect = null) @trusted pure nothrow @nogc; /* dmd @@@BUG11461@@@ */
 
-class ManualGC : GC
+// register GC in C constructor (_STI_)
+extern(C) pragma(crt_constructor) void _d_register_manual_gc()
 {
-    __gshared Array!Root roots;
-    __gshared Array!Range ranges;
-
-    static void initialize(ref GC gc)
-    {
-        import core.stdc.string;
+    import gc.registry;
+    registerGCFactory("manual", &initialize);
+}
 
-        if (config.gc != "manual")
-            return;
+private GC initialize()
+{
+    import core.stdc.string: memcpy;
 
-        auto p = cstdlib.malloc(__traits(classInstanceSize, ManualGC));
-        if (!p)
-            onOutOfMemoryError();
+    auto p = cstdlib.malloc(__traits(classInstanceSize, ManualGC));
+    if (!p)
+        onOutOfMemoryError();
 
-        auto init = typeid(ManualGC).initializer();
-        assert(init.length == __traits(classInstanceSize, ManualGC));
-        auto instance = cast(ManualGC) memcpy(p, init.ptr, init.length);
-        instance.__ctor();
+    auto init = typeid(ManualGC).initializer();
+    assert(init.length == __traits(classInstanceSize, ManualGC));
+    auto instance = cast(ManualGC) memcpy(p, init.ptr, init.length);
+    instance.__ctor();
 
-        gc = instance;
-    }
-
-    static void finalize(ref GC gc)
-    {
-        if (config.gc != "manual")
-            return;
+    return instance;
+}
 
-        auto instance = cast(ManualGC) gc;
-        instance.Dtor();
-        cstdlib.free(cast(void*) instance);
-    }
+class ManualGC : GC
+{
+    Array!Root roots;
+    Array!Range ranges;
 
     this()
     {
     }
 
-    void Dtor()
+    ~this()
     {
+        // TODO: cannot free as memory is overwritten and
+        //  the monitor is still read in rt_finalize (called by destroy)
+        // cstdlib.free(cast(void*) this);
     }
 
     void enable()

src/gc/proxy.d

@@ -13,11 +13,10 @@
  */
 module gc.proxy;
 
-import gc.impl.conservative.gc;
-import gc.impl.manual.gc;
 import gc.impl.proto.gc;
 import gc.config;
 import gc.gcinterface;
+import gc.registry : createGCInstance;
 
 static import core.memory;
 
@@ -36,17 +35,31 @@ private
 
 extern (C)
 {
+    // do not import GC modules, they might add a dependency to this whole module
+    void _d_register_conservative_gc();
+    void _d_register_manual_gc();
+
+    // if you don't want to include the default GCs, replace during link by another implementation
+    void* register_default_gcs()
+    {
+        pragma(inline, false);
+        // do not call, they register implicitly through pragma(crt_constructor)
+        // avoid being optimized away
+        auto reg1 = &_d_register_conservative_gc;
+        auto reg2 = &_d_register_manual_gc;
+        return reg1 < reg2 ? reg1 : reg2;
+    }
+
     void gc_init()
     {
         instanceLock.lock();
         if (!isInstanceInit)
         {
-            auto protoInstance = instance;
+            register_default_gcs();
             config.initialize();
-            ManualGC.initialize(instance);
-            ConservativeGC.initialize(instance);
-
-            if (instance is protoInstance)
+            auto protoInstance = instance;
+            auto newInstance = createGCInstance(config.gc);
+            if (newInstance is null)
             {
                 import core.stdc.stdio : fprintf, stderr;
                 import core.stdc.stdlib : exit;
@@ -58,7 +71,7 @@ extern (C)
                 // Shouldn't get here.
                 assert(0);
             }
-
+            instance = newInstance;
             // Transfer all ranges and roots to the real GC.
             (cast(ProtoGC) protoInstance).term();
             isInstanceInit = true;
@@ -108,9 +121,7 @@ extern (C)
                     instance.runFinalizers((cast(ubyte*)null)[0 .. size_t.max]);
                     break;
             }
-
-            ManualGC.finalize(instance);
-            ConservativeGC.finalize(instance);
+            destroy(instance);
         }
     }