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include/ruby/internal/intern/gc.h: add doxygen
Must not be a bad idea to improve documents. [ci skip]
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@ -20,37 +20,370 @@
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* extension libraries. They could be written in C++98.
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* @brief Public APIs related to ::rb_mGC.
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*/
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#include "ruby/internal/config.h"
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#ifdef STDC_HEADERS
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# include <stddef.h> /* size_t */
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#endif
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#if HAVE_SYS_TYPES_H
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# include <sys/types.h> /* ssize_t */
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#endif
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#include "ruby/internal/attr/cold.h"
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#include "ruby/internal/attr/noreturn.h"
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#include "ruby/internal/attr/nonnull.h"
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#include "ruby/internal/attr/pure.h"
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#include "ruby/internal/dllexport.h"
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#include "ruby/internal/value.h"
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#include "ruby/backward/2/attributes.h"
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RBIMPL_SYMBOL_EXPORT_BEGIN()
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/* gc.c */
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COLDFUNC NORETURN(void rb_memerror(void));
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PUREFUNC(int rb_during_gc(void));
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void rb_gc_mark_locations(const VALUE*, const VALUE*);
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void rb_mark_tbl(struct st_table*);
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void rb_mark_tbl_no_pin(struct st_table*);
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void rb_mark_set(struct st_table*);
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void rb_mark_hash(struct st_table*);
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RBIMPL_ATTR_COLD()
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RBIMPL_ATTR_NORETURN()
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/**
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* Triggers out-of-memory error. If possible it raises ::rb_eNoMemError. But
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* because we are running out of memory that is not always doable. This
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* function tries hard to show something, but ultimately can die silently.
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*
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* @exception rb_eNoMemError Raises it if possible.
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*/
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void rb_memerror(void);
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RBIMPL_ATTR_PURE()
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/**
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* Queries if the GC is busy.
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*
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* @retval 0 It isn't.
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* @retval 1 It is.
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*/
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int rb_during_gc(void);
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RBIMPL_ATTR_NONNULL((1))
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/**
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* Marks objects between the two pointers. This is one of the GC utility
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* functions that you can call when you design your own
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* ::rb_data_type_struct::dmark.
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*
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* @pre Continuous memory region from `start` to `end` shall be fully
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* addressable.
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* @param[out] start Pointer to an array of objects.
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* @param[out] end Pointer that terminates the array of objects.
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* @post Objects from `start` to `end`, both inclusive, are marked.
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*
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* @internal
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*
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* `end` can be NULL... But that just results in no-op.
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*/
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void rb_gc_mark_locations(const VALUE *start, const VALUE *end);
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/**
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* Identical to rb_mark_hash(), except it marks only values of the table and
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* leave their associated keys unmarked. This is one of the GC utility
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* functions that you can call when you design your own
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* ::rb_data_type_struct::dmark.
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*
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* @warning Of course it can break GC. Leave it unused if unsure.
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* @param[in] tbl A table to mark.
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* @post Values stored in `tbl` are marked.
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*/
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void rb_mark_tbl(struct st_table *tbl);
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/**
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* Identical to rb_mark_tbl(), except it marks objects using
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* rb_gc_mark_movable(). This is one of the GC utility functions that you can
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* call when you design your own ::rb_data_type_struct::dmark.
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*
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* @warning Of course it can break GC. Leave it unused if unsure.
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* @param[in] tbl A table to mark.
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* @post Values stored in `tbl` are marked.
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*/
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void rb_mark_tbl_no_pin(struct st_table *tbl);
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/**
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* Identical to rb_mark_hash(), except it marks only keys of the table and
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* leave their associated values unmarked. This is one of the GC utility
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* functions that you can call when you design your own
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* ::rb_data_type_struct::dmark.
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*
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* @warning Of course it can break GC. Leave it unused if unsure.
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* @param[in] tbl A table to mark.
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* @post Keys stored in `tbl` are marked.
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*/
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void rb_mark_set(struct st_table *tbl);
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/**
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* Marks keys and values associated inside of the given table. This is one of
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* the GC utility functions that you can call when you design your own
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* ::rb_data_type_struct::dmark.
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*
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* @param[in] tbl A table to mark.
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* @post Objects stored in `tbl` are marked.
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*/
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void rb_mark_hash(struct st_table *tbl);
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/**
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* Updates references inside of tables. After you marked values using
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* rb_mark_tbl_no_pin(), the objects inside of the table could of course be
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* moved. This function is to fixup those references. You can call this from
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* your ::rb_data_type_struct::dcompact.
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*
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* @param[out] ptr A table that potentially includes moved references.
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* @post Moved references, if any, are corrected.
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*/
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void rb_gc_update_tbl_refs(st_table *ptr);
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void rb_gc_mark_maybe(VALUE);
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void rb_gc_mark(VALUE);
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void rb_gc_mark_movable(VALUE);
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VALUE rb_gc_location(VALUE);
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void rb_gc_force_recycle(VALUE);
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/**
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* Identical to rb_gc_mark(), except it allows the passed value be a
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* non-object. For instance pointers to different type of memory regions are
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* allowed here. Such values are silently ignored. This is one of the GC
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* utility functions that you can call when you design your own
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* ::rb_data_type_struct::dmark.
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*
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* @param[out] obj A possible object.
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* @post `obj` is marked, if possible.
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*/
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void rb_gc_mark_maybe(VALUE obj);
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/**
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* Marks an object. This is one of the GC utility functions that you can call
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* when you design your own ::rb_data_type_struct::dmark.
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*
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* @param[out] obj Arbitrary Ruby object.
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* @post `obj` is marked.
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*/
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void rb_gc_mark(VALUE obj);
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/**
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* Maybe this is the only function provided for C extensions to control the
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* pinning of objects, so let us describe it in detail. These days Ruby's GC
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* is copying. As far as an object's physical address is guaranteed unused, it
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* can move around the object space. Our GC engine rearranges these objects
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* after it reclaims unreachable objects from our object space, so that the
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* space is compact (improves memory locality). This is called the
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* "compaction" phase, and works well most of the time... as far as there are
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* no C extensions. C extensions complicate the scenario because Ruby core
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* cannot detect any use of the physical address of an object inside of C
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* functions. In order to prevent memory corruptions, objects observable from
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* C extensions are "pinned"; they stick to where they are born until they die,
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* just in case any C extensions touch their raw pointers. This variant of
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* scheme is called "Mostly-Copying" garbage collector. Authors of C
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* extensions, however, can extremely carefully write them to become
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* compaction-aware. To do so avoid referring to a Ruby object from inside of
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* your struct in the first place. But if that is not possible, use this
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* function from your ::rb_data_type_struct::dmark then. This way objects
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* marked using it are considered movable. If you chose this way you have to
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* manually fix up locations of such moved pointers using rb_gc_location().
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*
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* @see Bartlett, Joel F., "Compacting Garbage Collection with Ambiguous
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* Roots", ACM SIGPLAN Lisp Pointers Volume 1 Issue 6 pp. 3-12,
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* April-May-June, 1988. https://doi.org/10.1145/1317224.1317225
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*
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* @param[in] obj Object that is movable.
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* @post Values stored in `tbl` are marked.
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*/
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void rb_gc_mark_movable(VALUE obj);
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/**
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* Finds a new "location" of an object. An object can be moved on compaction.
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* This function projects its new abode, or just returns the passed object if
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* not moved. This is one of the GC utility functions that you can call when
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* you design your own ::rb_data_type_struct::dcompact.
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*
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* @param[in] obj An object, possibly already moved to somewhere else.
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* @return An object, which holds the current contents of former `obj`.
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*/
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VALUE rb_gc_location(VALUE obj);
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/**
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* Asserts that the passed object is no longer needed. Such objects are
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* reclaimed sooner or later so this function is not mandatory. But sometimes
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* you can know from your application knowledge that an object is surely dead
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* at some point. Calling this as a hint can be a polite way.
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*
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* @param[out] obj Object, dead.
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* @pre `obj` have never been passed to this function before.
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* @post `obj` could be invalidated.
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* @warning It is a failure to pass an object multiple times to this
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* function.
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*/
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void rb_gc_force_recycle(VALUE obj);
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/**
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* Triggers a GC process. This was the only GC entry point that we had at the
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* beginning. Over time our GC evolved. Now what this function does is just a
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* very simplified variation of the entire GC algorithms. A series of
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* procedures kicked by this API is called a "full" GC.
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*
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* - It immediately scans the entire object space to sort the dead.
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* - It immediately reclaims any single dead bodies to reuse later.
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*
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* It is worth noting that the procedures above do not include evaluations of
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* finalisers. They run later.
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*
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* @internal
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*
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* Finalisers are deferred until we can handle interrupts. See
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* `rb_postponed_job_flush` in vm_trace.c.
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*
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* Of course there are GC that are not "full". For instance this one and the
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* GC which runs when we are running out of memory are different. See
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* `gc_profile_record_flag` defined in gc.c for the kinds of GC.
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*
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* In spite of the name this is not what everything that a GC can trigger. As
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* of writing it seems this function does not trigger compaction. But this
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* might change in future.
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*/
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void rb_gc(void);
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void rb_gc_copy_finalizer(VALUE,VALUE);
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/**
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* Copy&paste an object's finaliser to another. This is one of the GC utility
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* functions that you can call when you design your own `initialize_copy`,
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* `initialize_dup`, `initialize_clone`.
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*
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* @param[out] dst Destination object.
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* @param[in] src Source object.
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* @post `dst` and `src` share the same finaliser.
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*
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* @internal
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*
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* But isn't it easier for you to call super, and let `Object#intialize_copy`
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* call this function instead?
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*/
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void rb_gc_copy_finalizer(VALUE dst, VALUE src);
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/**
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* (Re-) enables GC. This makes sense only after you called rb_gc_disable().
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*
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* @retval RUBY_Qtrue GC was disabled before.
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* @retval RUBY_Qfalse GC was enabled before.
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* @post GC is enabled.
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*
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* @internal
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*
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* This is one of such exceptional functions that does not raise both Ruby
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* exceptions and C++ exceptions.
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*/
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VALUE rb_gc_enable(void);
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/**
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* Disables GC. This prevents automatic GC runs when the process is running
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* out of memory. Such situations shall result in rb_memerror(). However this
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* does not prevent users from manually invoking rb_gc(). That should work.
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* People abused this by disabling GC at the beginning of an event loop,
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* process events without GC overheads, then manually force reclaiming garbage
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* at the bottom of the loop. However because our GC is now much smarter than
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* just calling rb_gc(), this technique is proven to be sub-optimal these days.
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* It is believed that there is currently practically no needs of this
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* function.
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*
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* @retval RUBY_Qtrue GC was disabled before.
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* @retval RUBY_Qfalse GC was enabled before.
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* @post GC is disabled.
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*/
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VALUE rb_gc_disable(void);
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/**
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* Identical to rb_gc(), except the return value.
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*
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* @return Always returns ::RUBY_Qnil.
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*/
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VALUE rb_gc_start(void);
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VALUE rb_define_finalizer(VALUE, VALUE);
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VALUE rb_undefine_finalizer(VALUE);
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/**
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* Assigns a finaliser for an object. Each objects can have objects (typically
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* blocks) that run immediately after that object dies. They are called
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* finalisers of an object. This function associates a finaliser object with a
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* target object.
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*
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* @note Note that finalisers run _after_ the object they finalise dies. You
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* cannot for instance call its methods.
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* @note If your finaliser references the object it finalises that object
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* loses any chance to become a garbage; effectively leaks memory until
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* the end of the process.
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*
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* @param[in] obj Target to finalise.
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* @param[in] block Something `call`able.
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* @exception rb_eRuntimeError Somehow `obj` cannot have finalisers.
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* @exception rb_eFrozenError `obj` is frozen.
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* @exception rb_eArgError `block` doesn't respond to `call`.
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* @return The passed `block`.
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* @post `block` runs after `obj` dies.
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*/
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VALUE rb_define_finalizer(VALUE obj, VALUE block);
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/**
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* Modifies the object so that it has no finalisers at all. This function is
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* mainly provided for symmetry. No practical usages can be thought of.
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*
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* @param[out] obj Object to clear its finalisers.
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* @exception rb_eFrozenError `obj` is frozen.
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* @return The passed `obj`.
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* @post `obj` has no finalisers.
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* @note There is no way to undefine a specific part of many finalisers
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* that `obj` could have. All you can do is to clear them all.
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*/
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VALUE rb_undefine_finalizer(VALUE obj);
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/**
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* Identical to rb_gc_stat(), with "count" parameter.
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*
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* @return Lifetime total number of runs of GC.
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*/
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size_t rb_gc_count(void);
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size_t rb_gc_stat(VALUE);
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VALUE rb_gc_latest_gc_info(VALUE);
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void rb_gc_adjust_memory_usage(ssize_t);
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/**
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* Obtains various GC related profiles. The parameter can be either a Symbol
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* or a Hash. If a Hash is passed, it is filled with everything currently
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* available. If a Symbol is passed just that portion is returned.
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*
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* Possible variations of keys you can pass here change from version to
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* version. You can get the list of known keys by passing an empty hash and
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* let it be filled.
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*
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* @param[in,out] key_or_buf A Symbol, or a Hash.
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* @exception rb_eTypeError Neither Symbol nor Hash.
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* @exception rb_eFrozenError Frozen hash is passed.
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* @return In case a Hash is passed it returns 0. Otherwise the
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* profile value associated with the given key is returned.
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* @post In case a Hash is passed it is filled with values.
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*/
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size_t rb_gc_stat(VALUE key_or_buf);
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/**
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* Obtains various info regarding the most recent GC run. This includes for
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* instance the reason of the GC. The parameter can be either a Symbol or a
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* Hash. If a Hash is passed, it is filled with everything currently
|
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* available. If a Symbol is passed just that portion is returned.
|
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*
|
||||
* Possible variations of keys you can pass here change from version to
|
||||
* version. You can get the list of known keys by passing an empty hash and
|
||||
* let it be filled.
|
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*
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* @param[in,out] key_or_buf A Symbol, or a Hash.
|
||||
* @exception rb_eTypeError Neither Symbol nor Hash.
|
||||
* @exception rb_eFrozenError Frozen hash is passed.
|
||||
* @return In case a Hash is passed it returns that hash. Otherwise
|
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* the profile value associated with the given key is returned.
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* @post In case a Hash is passed it is filled with values.
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*/
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VALUE rb_gc_latest_gc_info(VALUE key_or_buf);
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||||
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||||
/**
|
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* Informs that there are external memory usages. Our GC runs when we are
|
||||
* running out of memory. The amount of memory, however, can increase/decrease
|
||||
* behind-the-scene. For instance DLLs can allocate memories using `mmap(2)`
|
||||
* etc, which are opaque to us. Registering such external allocations using
|
||||
* this function enables proper detection of how much memories an object used
|
||||
* as a whole. That will trigger GCs more often than it would otherwise. You
|
||||
* can also pass negative numbers here, to indicate that such external
|
||||
* allocations are gone.
|
||||
*
|
||||
* @param[in] diff Amount of memory increased(+)/decreased(-).
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||||
*/
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||||
void rb_gc_adjust_memory_usage(ssize_t diff);
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||||
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||||
RBIMPL_SYMBOL_EXPORT_END()
|
||||
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||||
|
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