xo-alloc: reserve virtual memory, commit pages on demand

include/xo/alloc/ArenaAlloc.hpp

@@ -24,6 +24,8 @@ namespace xo {
          **/
         class ArenaAlloc : public IAlloc {
         public:
+            ArenaAlloc(const ArenaAlloc &) = delete;
+            ArenaAlloc(ArenaAlloc &&) = delete;
             ~ArenaAlloc();
 
             /** create allocator with capacity @p z,
@@ -38,10 +40,14 @@ namespace xo {
             void capture_object_statistics(capture_phase phase,
                                            ObjectStatistics * p_dest) const;
 
+            /** expand available (i.e. committed) space to size @p z **/
+            bool expand(std::size_t z);
+
             // inherited from IAlloc...
 
             virtual const std::string & name() const final override;
             virtual std::size_t size() const final override;
+            virtual std::size_t committed() const final override;
             virtual std::size_t available() const final override;
             virtual std::size_t allocated() const final override;
             virtual bool contains(const void * x) const final override;
@@ -54,6 +60,9 @@ namespace xo {
             virtual void checkpoint() final override;
             virtual std::byte * alloc(std::size_t z) final override;
 
+            ArenaAlloc & operator=(const ArenaAlloc &) = delete;
+            ArenaAlloc & operator=(ArenaAlloc &&) = delete;
+
         private:
             ArenaAlloc(const std::string & name,
                        std::size_t z, bool debug_flag);
@@ -67,8 +76,15 @@ namespace xo {
             /** optional instance name, for diagnostics **/
             std::string name_;
 
+            /** size of a VM page **/
+            std::size_t page_z_;
+
             /** allocator owns memory in range [@ref lo_, @ref hi_) **/
             std::byte * lo_ = nullptr;
+            /** prefix of this size is actually committed.
+             *  Remainder uses uncommitted virtual address space
+             **/
+            std::size_t committed_z_ = 0;
             /** checkpoint (for GC support); divides objects into
              *  older (addresses below checkpoint)
              *  and younger (addresses above checkpoint)
@@ -76,9 +92,9 @@ namespace xo {
             std::byte * checkpoint_;
             /** free pointer. memory in range [@ref free_, @ref limit_) available **/
             std::byte * free_ptr_ = nullptr;
-            /** soft limit: end of released memory **/
+            /** soft limit: end of committed virtual memory **/
             std::byte * limit_ = nullptr;
-            /** hard limit: end of allocated memory **/
+            /** hard limit: end of reserved virtual memory **/
             std::byte * hi_ = nullptr;
             /** true to enable detailed debug logging **/
             bool debug_flag_ = false;

include/xo/alloc/GC.hpp

@@ -164,7 +164,8 @@ namespace xo {
              *  since one role is always held empty between collections.
              **/
             virtual std::size_t size() const final override;
-
+            /** for committed count both to-space and from-space **/
+            virtual std::size_t committed() const final override;
             virtual std::size_t allocated() const final override;
             virtual std::size_t available() const final override;
             /** only tests to-space **/
@@ -194,10 +195,6 @@ namespace xo {
             virtual std::byte * alloc(std::size_t z) final override;
             virtual std::byte * alloc_gc_copy(std::size_t z, const void * src) final override;
 
-#ifdef REDLINE_MEMORY
-            virtual void release_redline_memory() final override;
-#endif
-
         private:
             ListAlloc * nursery_to() const { return nursery(role::to_space); }
             ListAlloc * nursery_from() const { return nursery(role::from_space); }
@@ -208,6 +205,8 @@ namespace xo {
             ListAlloc * nursery(role r) const { return nursery_[role2int(r)].get(); }
             ListAlloc * tenured(role r) const { return tenured_[role2int(r)].get(); }
 
+            MutationLog * mutation_log(role r) const { return mutation_log_[role2int(r)].get(); }
+
             /** begin GC now **/
             void execute_gc(generation g);
             /** cleanup phase.  aux function for @ref execute_gc **/

include/xo/alloc/IAlloc.hpp

@@ -31,10 +31,12 @@ namespace xo {
 
             /** optional name for this allocator; labelling for diagnostics **/
             virtual const std::string & name() const = 0;
-            /** allocator size in bytes (up to soft limit).
+            /** allocator size in bytes (up to reserved limit)
              *  Includes unallocated mmeory
              **/
             virtual std::size_t size() const = 0;
+            /** committed size in bytes **/
+            virtual std::size_t committed() const = 0;
             /** number of unallocated bytes available (up to soft limit)
              *  from this allocator
              **/

include/xo/alloc/ListAlloc.hpp

@@ -55,6 +55,7 @@ namespace xo {
 
             virtual const std::string & name() const final override;
             virtual std::size_t size() const final override;
+            virtual std::size_t committed() const final override;
             virtual std::size_t available() const final override;
             virtual std::size_t allocated() const final override;
             virtual bool contains(const void * x) const final override;