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/* -----------------------------------------------------------------------------
*
* (c) The GHC Team, 1998-2004
*
* External Storage Manger Interface
*
* ---------------------------------------------------------------------------*/
#ifndef RTS_STORAGE_GC_H
#define RTS_STORAGE_GC_H
#include <stddef.h>
#include "rts/OSThreads.h"
/* -----------------------------------------------------------------------------
* Generational GC
*
* We support an arbitrary number of generations, with an arbitrary number
* of steps per generation. Notes (in no particular order):
*
* - all generations except the oldest should have the same
* number of steps. Multiple steps gives objects a decent
* chance to age before being promoted, and helps ensure that
* we don't end up with too many thunks being updated in older
* generations.
*
* - the oldest generation has one step. There's no point in aging
* objects in the oldest generation.
*
* - generation 0, step 0 (G0S0) is the allocation area. It is given
* a fixed set of blocks during initialisation, and these blocks
* normally stay in G0S0. In parallel execution, each
* Capability has its own nursery.
*
* - during garbage collection, each step which is an evacuation
* destination (i.e. all steps except G0S0) is allocated a to-space.
* evacuated objects are allocated into the step's to-space until
* GC is finished, when the original step's contents may be freed
* and replaced by the to-space.
*
* - the mutable-list is per-generation (not per-step). G0 doesn't
* have one (since every garbage collection collects at least G0).
*
* - block descriptors contain pointers to both the step and the
* generation that the block belongs to, for convenience.
*
* - static objects are stored in per-generation lists. See GC.c for
* details of how we collect CAFs in the generational scheme.
*
* - large objects are per-step, and are promoted in the same way
* as small objects, except that we may allocate large objects into
* generation 1 initially.
*
* ------------------------------------------------------------------------- */
typedef struct step_ {
unsigned int no; // step number in this generation
unsigned int abs_no; // absolute step number
struct generation_ * gen; // generation this step belongs to
unsigned int gen_no; // generation number (cached)
bdescr * blocks; // blocks in this step
unsigned int n_blocks; // number of blocks
unsigned int n_words; // number of words
struct step_ * to; // destination step for live objects
bdescr * large_objects; // large objects (doubly linked)
unsigned int n_large_blocks; // no. of blocks used by large objs
StgTSO * threads; // threads in this step
// linked via global_link
// ------------------------------------
// Fields below are used during GC only
// During GC, if we are collecting this step, blocks and n_blocks
// are copied into the following two fields. After GC, these blocks
// are freed.
#if defined(THREADED_RTS)
char pad[128]; // make sure the following is
// on a separate cache line.
SpinLock sync_large_objects; // lock for large_objects
// and scavenged_large_objects
#endif
int mark; // mark (not copy)? (old gen only)
int compact; // compact (not sweep)? (old gen only)
bdescr * old_blocks; // bdescr of first from-space block
unsigned int n_old_blocks; // number of blocks in from-space
unsigned int live_estimate; // for sweeping: estimate of live data
bdescr * part_blocks; // partially-full scanned blocks
unsigned int n_part_blocks; // count of above
bdescr * scavenged_large_objects; // live large objs after GC (d-link)
unsigned int n_scavenged_large_blocks; // size (not count) of above
bdescr * bitmap; // bitmap for compacting collection
StgTSO * old_threads;
} step;
typedef struct generation_ {
unsigned int no; // generation number
step * steps; // steps
unsigned int n_steps; // number of steps
unsigned int max_blocks; // max blocks in step 0
bdescr *mut_list; // mut objects in this gen (not G0)
// stats information
unsigned int collections;
unsigned int par_collections;
unsigned int failed_promotions;
// temporary use during GC:
bdescr *saved_mut_list;
} generation;
extern generation * generations;
extern generation * g0;
extern step * g0s0;
extern generation * oldest_gen;
extern step * all_steps;
extern nat total_steps;
/* -----------------------------------------------------------------------------
Generic allocation
StgPtr allocateInGen(generation *g, nat n)
Allocates a chunk of contiguous store
n words long in generation g,
returning a pointer to the first word.
Always succeeds.
StgPtr allocate(nat n) Equaivalent to allocateInGen(g0)
StgPtr allocateLocal(Capability *cap, nat n)
Allocates memory from the nursery in
the current Capability. This can be
done without taking a global lock,
unlike allocate().
StgPtr allocatePinned(nat n) Allocates a chunk of contiguous store
n words long, which is at a fixed
address (won't be moved by GC).
Returns a pointer to the first word.
Always succeeds.
NOTE: the GC can't in general handle
pinned objects, so allocatePinned()
can only be used for ByteArrays at the
moment.
Don't forget to TICK_ALLOC_XXX(...)
after calling allocate or
allocatePinned, for the
benefit of the ticky-ticky profiler.
rtsBool doYouWantToGC(void) Returns True if the storage manager is
ready to perform a GC, False otherwise.
lnat allocatedBytes(void) Returns the number of bytes allocated
via allocate() since the last GC.
Used in the reporting of statistics.
-------------------------------------------------------------------------- */
StgPtr allocate ( lnat n );
StgPtr allocateInGen ( generation *g, lnat n );
StgPtr allocateLocal ( Capability *cap, lnat n );
StgPtr allocatePinned ( lnat n );
lnat allocatedBytes ( void );
/* memory allocator for executable memory */
void * allocateExec(unsigned int len, void **exec_addr);
void freeExec (void *p);
/* -----------------------------------------------------------------------------
Performing Garbage Collection
-------------------------------------------------------------------------- */
void performGC(void);
void performMajorGC(void);
/* -----------------------------------------------------------------------------
The CAF table - used to let us revert CAFs in GHCi
-------------------------------------------------------------------------- */
void newCAF (StgClosure*);
void newDynCAF (StgClosure *);
void revertCAFs (void);
/* set to disable CAF garbage collection in GHCi. */
/* (needed when dynamic libraries are used). */
extern rtsBool keepCAFs;
#endif /* RTS_STORAGE_GC_H */
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