xo-gc: improve public/private between MutationLogStore and X1

include/xo/gc/MutationLogConfig.hpp

@@ -17,55 +17,26 @@ namespace xo {
         class MutationLogConfig {
         public:
             MutationLogConfig(std::uint32_t ngen,
-#ifdef OBSOLETE // in GCObjectStore
-                              std::uint32_t survive,
-#endif
                               std::size_t mlog_z,
+                              bool enabled_flag,
                               bool debug_flag);
 
-#ifdef OBSOLETE
-            /** generation that would contain an object that has survived
-             *  @p age collections. Equals the number of times object
-             *  has been promoted.
-             *
-             *  Must be consistent
-             **/
-            Generation age2gen(object_age age) const noexcept {
-                return Generation(age % n_survive_threshold_);
-            }
-#endif
-
-#ifdef OBSOLETE
-            /** age threshold for promotion to generation @p g **/
-            uint32_t promotion_threshold(Generation g) const noexcept {
-
-                // TODO: may consider replacing with table-lookup
-                // Require: if two distinct ages promote to some gen g at the same time,
-                //          then they also promote to gen g+k at the same time for all k>0.
-
-                return  g * n_survive_threshold_;
-            }
-#endif
-
         public:
             /** number of generations in use.
              *  Same as @ref X1CollectorConfig::n_generation_
              **/
             std::uint32_t n_generation_ = 0;
 
-#ifdef OBSOLETE
-            /** Number of promotion steps.
-             *  An object that survives this number of collections
-             *  advances to the next generation.
-             **/
-            uint32_t n_survive_threshold_ = 2;
-#endif
-
             /** storage for xgen pointer bookkeeping (aka remembered sets).
              *  Use 3x this value per generation
              **/
             std::size_t mutation_log_z_ = 1024;
 
+            /** true if mlog feature enabled (i.e. incremental gc enabled).
+             *  false to disable (in which case only full gc supported)
+             **/
+            bool enabled_flag_ = false;
+
             /** true to enable debug logging **/
             bool debug_flag_ = false;
         };

include/xo/gc/MutationLogStore.hpp

@@ -40,13 +40,40 @@ namespace xo {
             void visit_pools(const MemorySizeVisitor & visitor) const;
 
             /** verify consistent mlog state,
-             *  on behalf of collector @p gc.
+             *  on behalf of gc-aware object store @p gc.
              *  (using gc to identify location of objects).
              *  Update counters in @p *p_verify_stats.
              **/
             void verify_ok(GCObjectStore * gc,
                            X1VerifyStats * p_verify_stats) noexcept;
 
+            /** on behalf of gc-aware object store @p gc,
+             *  change the value of a child pointer at @p p_lhs
+             *  with parent object @p parent.  p_lhs and parent must belong
+             *  to the same allocation.
+             **/
+            void assign_member(GCObjectStore * gc,
+                               void * parent,
+                               obj<AGCObject> * p_lhs,
+                               obj<AGCObject> rhs);
+
+            /** swap {to, from} roles
+             **/
+            void swap_roles(Generation upto) noexcept;
+
+            /** On behalf of collector @p gc:
+             *
+             *  forward mutation logs, for generations 0 <= g < @p upto,
+             *  from from-space to to-space.
+             **/
+            void forward_mutation_log(DX1Collector * gc,
+                                      Generation upto);
+
+        private:
+            /** aux init function: create mutation log **/
+            MutationLog _make_mlog(uint32_t igen, char tag_char,
+                                   size_t mlog_z, std::size_t page_z);
+
             /** Append a single mutation to log for generation @p dest_g
              *  Mutation modifies @p parent at address @p addr,
              *  to refer to @p rhs.
@@ -64,27 +91,10 @@ namespace xo {
              *  pointer.  This means can alway recover that pointer
              *  by consulting the AllocHeader for the pointer target
              */
-            void append_mutation(Generation dest_g,
-                                 void * parent,
-                                 void ** addr,
-                                 obj<AGCObject> rhs);
-
-            /** swap {to, from} roles
-             **/
-            void swap_roles(Generation upto) noexcept;
-
-            /** On behalf of collector @p gc:
-             *
-             *  forward mutation logs, for generations 0 <= g < @p upto,
-             *  from from-space to to-space.
-             **/
-            void forward_mutation_log(DX1Collector * gc,
-                                      Generation upto);
-
-        private:
-            /** aux init function: create mutation log **/
-            MutationLog _make_mlog(uint32_t igen, char tag_char,
-                                   size_t mlog_z, std::size_t page_z);
+            void _append_mutation(Generation dest_g,
+                                  void * parent,
+                                  void ** addr,
+                                  obj<AGCObject> rhs);
 
             /** On behalf of collctor @p gc:
              *

include/xo/gc/X1CollectorConfig.hpp

@@ -51,8 +51,11 @@ namespace xo {
 
             /** fetch configuration for mutation log store **/
             MutationLogConfig mlog_config() const noexcept {
+                bool mlog_enabled_flag = allow_incremental_gc_;
+
                 return MutationLogConfig(n_generation_,
                                          mutation_log_z_,
+                                         mlog_enabled_flag,
                                          debug_flag_);
             }