diff options
Diffstat (limited to 'erts/emulator/beam/erl_db_hash.c')
| -rw-r--r-- | erts/emulator/beam/erl_db_hash.c | 648 |
1 files changed, 340 insertions, 308 deletions
diff --git a/erts/emulator/beam/erl_db_hash.c b/erts/emulator/beam/erl_db_hash.c index 5e6fe4f460..939ae57192 100644 --- a/erts/emulator/beam/erl_db_hash.c +++ b/erts/emulator/beam/erl_db_hash.c @@ -84,25 +84,28 @@ #include "erl_db_hash.h" -#ifdef MYDEBUG /* Will fail test case ets_SUITE:memory */ -# define IF_DEBUG(x) x -# define MY_ASSERT(x) ASSERT(x) -#else -# define IF_DEBUG(x) -# define MY_ASSERT(x) -#endif - /* * The following symbols can be manipulated to "tune" the linear hash array */ -#define CHAIN_LEN 6 /* Medium bucket chain len */ +#define GROW_LIMIT(NACTIVE) ((NACTIVE)*1) +#define SHRINK_LIMIT(NACTIVE) ((NACTIVE) / 2) -/* Number of slots per segment */ -#define SEGSZ_EXP 8 -#define SEGSZ (1 << SEGSZ_EXP) -#define SEGSZ_MASK (SEGSZ-1) +/* +** We want the first mandatory segment to be small (to reduce minimal footprint) +** and larger extra segments (to reduce number of alloc/free calls). +*/ -#define NSEG_1 2 /* Size of first segment table (must be at least 2) */ +/* Number of slots in first segment */ +#define FIRST_SEGSZ_EXP 8 +#define FIRST_SEGSZ (1 << FIRST_SEGSZ_EXP) +#define FIRST_SEGSZ_MASK (FIRST_SEGSZ - 1) + +/* Number of slots per extra segment */ +#define EXT_SEGSZ_EXP 11 +#define EXT_SEGSZ (1 << EXT_SEGSZ_EXP) +#define EXT_SEGSZ_MASK (EXT_SEGSZ-1) + +#define NSEG_1 (ErtsSizeofMember(DbTableHash,first_segtab) / sizeof(struct segment*)) #define NSEG_2 256 /* Size of second segment table */ #define NSEG_INC 128 /* Number of segments to grow after that */ @@ -123,7 +126,9 @@ #define NACTIVE(tb) ((int)erts_smp_atomic_read_nob(&(tb)->nactive)) #define NITEMS(tb) ((int)erts_smp_atomic_read_nob(&(tb)->common.nitems)) -#define BUCKET(tb, i) SEGTAB(tb)[(i) >> SEGSZ_EXP]->buckets[(i) & SEGSZ_MASK] +#define SLOT_IX_TO_SEG_IX(i) (((i)+(EXT_SEGSZ-FIRST_SEGSZ)) >> EXT_SEGSZ_EXP) + +#define BUCKET(tb, i) SEGTAB(tb)[SLOT_IX_TO_SEG_IX(i)]->buckets[(i) & EXT_SEGSZ_MASK] /* * When deleting a table, the number of records to delete. @@ -189,6 +194,7 @@ static ERTS_INLINE int add_fixed_deletion(DbTableHash* tb, int ix, #ifdef ERTS_SMP # define DB_HASH_LOCK_MASK (DB_HASH_LOCK_CNT-1) # define GET_LOCK(tb,hval) (&(tb)->locks->lck_vec[(hval) & DB_HASH_LOCK_MASK].lck) +# define GET_LOCK_MAYBE(tb,hval) ((tb)->common.is_thread_safe ? NULL : GET_LOCK(tb,hval)) /* Fine grained read lock */ static ERTS_INLINE erts_smp_rwmtx_t* RLOCK_HASH(DbTableHash* tb, HashValue hval) @@ -318,27 +324,23 @@ struct mp_info { /* A table segment */ struct segment { - HashDbTerm* buckets[SEGSZ]; -#ifdef MYDEBUG - int is_ext_segment; -#endif + HashDbTerm* buckets[1]; }; +#define SIZEOF_SEGMENT(N) \ + (offsetof(struct segment,buckets) + sizeof(HashDbTerm*)*(N)) -/* A segment that also contains a segment table */ -struct ext_segment { - struct segment s; /* The segment itself. Must be first */ - +/* An extended segment table */ +struct ext_segtab { +#ifdef ERTS_SMP + ErtsThrPrgrLaterOp lop; +#endif struct segment** prev_segtab; /* Used when table is shrinking */ - int nsegs; /* Size of segtab */ + int prev_nsegs; /* Size of prev_segtab */ + int nsegs; /* Size of this segtab */ struct segment* segtab[1]; /* The segment table */ }; -#define SIZEOF_EXTSEG(NSEGS) \ - (offsetof(struct ext_segment,segtab) + sizeof(struct segment*)*(NSEGS)) - -#if defined(DEBUG) || defined(VALGRIND) -# define EXTSEG(SEGTAB_PTR) \ - ((struct ext_segment*) (((char*)(SEGTAB_PTR)) - offsetof(struct ext_segment,segtab))) -#endif +#define SIZEOF_EXT_SEGTAB(NSEGS) \ + (offsetof(struct ext_segtab,segtab) + sizeof(struct segment*)*(NSEGS)) static ERTS_INLINE void SET_SEGTAB(DbTableHash* tb, @@ -348,49 +350,22 @@ static ERTS_INLINE void SET_SEGTAB(DbTableHash* tb, erts_smp_atomic_set_wb(&tb->segtab, (erts_aint_t) segtab); else erts_smp_atomic_set_nob(&tb->segtab, (erts_aint_t) segtab); -#ifdef VALGRIND - tb->top_ptr_to_segment_with_active_segtab = EXTSEG(segtab); -#endif } -/* How the table segments relate to each other: - - ext_segment: ext_segment: "plain" segment - #=================# #================# #=============# - | bucket[0] |<--+ +------->| bucket[256] | +->| bucket[512] | - | bucket[1] | | | | [257] | | | [513] | - : : | | : : | : : - | bucket[255] | | | | [511] | | | [767] | - |-----------------| | | |----------------| | #=============# - | prev_segtab=NULL| | | +--<---prev_segtab | | - | nsegs = 2 | | | | | nsegs = 256 | | -+->| segtab[0] -->-------+---|---|--<---segtab[0] |<-+ | -| | segtab[1] -->-----------+---|--<---segtab[1] | | | -| #=================# | | segtab[2] -->-----|--+ ext_segment: -| | : : | #================# -+----------------<---------------+ | segtab[255] ->----|----->| bucket[255*256]| - #================# | | | - | : : - | |----------------| - +----<---prev_segtab | - : : -*/ - /* ** Forward decl's (static functions) */ -static struct ext_segment* alloc_ext_seg(DbTableHash* tb, unsigned seg_ix, - struct segment** old_segtab); -static int alloc_seg(DbTableHash *tb); +static struct ext_segtab* alloc_ext_segtab(DbTableHash* tb, unsigned seg_ix); +static void alloc_seg(DbTableHash *tb); static int free_seg(DbTableHash *tb, int free_records); static HashDbTerm* next(DbTableHash *tb, Uint *iptr, erts_smp_rwmtx_t** lck_ptr, HashDbTerm *list); static HashDbTerm* search_list(DbTableHash* tb, Eterm key, HashValue hval, HashDbTerm *list); -static void shrink(DbTableHash* tb, int nactive); -static void grow(DbTableHash* tb, int nactive); +static void shrink(DbTableHash* tb, int nitems); +static void grow(DbTableHash* tb, int nitems); static Eterm build_term_list(Process* p, HashDbTerm* ptr1, HashDbTerm* ptr2, Uint sz, DbTableHash*); static int analyze_pattern(DbTableHash *tb, Eterm pattern, @@ -463,9 +438,10 @@ db_finalize_dbterm_hash(int cret, DbUpdateHandle* handle); static ERTS_INLINE void try_shrink(DbTableHash* tb) { int nactive = NACTIVE(tb); - if (nactive > SEGSZ && NITEMS(tb) < (nactive * CHAIN_LEN) + int nitems = NITEMS(tb); + if (nactive > FIRST_SEGSZ && nitems < SHRINK_LIMIT(nactive) && !IS_FIXED(tb)) { - shrink(tb, nactive); + shrink(tb, nitems); } } @@ -662,16 +638,20 @@ int db_create_hash(Process *p, DbTable *tbl) { DbTableHash *tb = &tbl->hash; - erts_smp_atomic_init_nob(&tb->szm, SEGSZ_MASK); - erts_smp_atomic_init_nob(&tb->nactive, SEGSZ); + erts_smp_atomic_init_nob(&tb->szm, FIRST_SEGSZ_MASK); + erts_smp_atomic_init_nob(&tb->nactive, FIRST_SEGSZ); erts_smp_atomic_init_nob(&tb->fixdel, (erts_aint_t)NULL); erts_smp_atomic_init_nob(&tb->segtab, (erts_aint_t)NULL); - SET_SEGTAB(tb, alloc_ext_seg(tb,0,NULL)->segtab); + SET_SEGTAB(tb, tb->first_segtab); tb->nsegs = NSEG_1; - tb->nslots = SEGSZ; + tb->nslots = FIRST_SEGSZ; + tb->first_segtab[0] = (struct segment*) erts_db_alloc(ERTS_ALC_T_DB_SEG, + (DbTable *) tb, + SIZEOF_SEGMENT(FIRST_SEGSZ)); + sys_memset(tb->first_segtab[0], 0, SIZEOF_SEGMENT(FIRST_SEGSZ)); - erts_smp_atomic_init_nob(&tb->is_resizing, 0); #ifdef ERTS_SMP + erts_smp_atomic_init_nob(&tb->is_resizing, 0); if (tb->common.type & DB_FINE_LOCKED) { erts_smp_rwmtx_opt_t rwmtx_opt = ERTS_SMP_RWMTX_OPT_DEFAULT_INITER; int i; @@ -686,7 +666,7 @@ int db_create_hash(Process *p, DbTable *tbl) erts_smp_rwmtx_init_opt_x(&tb->locks->lck_vec[i].lck, &rwmtx_opt, "db_hash_slot", make_small(i)); } - /* This important property is needed to guarantee that the buckets + /* This important property is needed to guarantee the two buckets * involved in a grow/shrink operation it protected by the same lock: */ ASSERT(erts_smp_atomic_read_nob(&tb->nactive) % DB_HASH_LOCK_CNT == 0); @@ -862,8 +842,8 @@ Lnew: WUNLOCK_HASH(lck); { int nactive = NACTIVE(tb); - if (nitems > nactive * (CHAIN_LEN+1) && !IS_FIXED(tb)) { - grow(tb, nactive); + if (nitems > GROW_LIMIT(nactive) && !IS_FIXED(tb)) { + grow(tb, nitems); } } CHECK_TABLES(); @@ -1514,6 +1494,7 @@ static int db_select_chunk_hash(Process *p, DbTable *tbl, match_list = CONS(hp, match_res, match_list); ++got; } + --num_left; } current = current->next; } @@ -1531,7 +1512,6 @@ static int db_select_chunk_hash(Process *p, DbTable *tbl, } } else { /* Key is variable */ - --num_left; if ((slot_ix=next_slot(tb,slot_ix,&lck)) == 0) { slot_ix = -1; @@ -2250,12 +2230,12 @@ static int db_free_table_continue_hash(DbTable *tbl) done /= 2; while(tb->nslots != 0) { - free_seg(tb, 1); + done += 1 + EXT_SEGSZ/64 + free_seg(tb, 1); /* * If we have done enough work, get out here. */ - if (++done >= (DELETE_RECORD_LIMIT / CHAIN_LEN / SEGSZ)) { + if (done >= DELETE_RECORD_LIMIT) { return 0; /* Not done */ } } @@ -2414,90 +2394,81 @@ static int analyze_pattern(DbTableHash *tb, Eterm pattern, return DB_ERROR_NONE; } -static struct ext_segment* alloc_ext_seg(DbTableHash* tb, unsigned seg_ix, - struct segment** old_segtab) +static struct ext_segtab* alloc_ext_segtab(DbTableHash* tb, unsigned seg_ix) { - int nsegs; - struct ext_segment* eseg; + struct segment** old_segtab = SEGTAB(tb); + int nsegs = 0; + struct ext_segtab* est; + ASSERT(seg_ix >= NSEG_1); switch (seg_ix) { - case 0: nsegs = NSEG_1; break; - case 1: nsegs = NSEG_2; break; - default: nsegs = seg_ix + NSEG_INC; break; - } - eseg = (struct ext_segment*) erts_db_alloc_fnf(ERTS_ALC_T_DB_SEG, - (DbTable *) tb, - SIZEOF_EXTSEG(nsegs)); - ASSERT(eseg != NULL); - sys_memset(&eseg->s, 0, sizeof(struct segment)); - IF_DEBUG(eseg->s.is_ext_segment = 1); - eseg->prev_segtab = old_segtab; - eseg->nsegs = nsegs; - if (old_segtab) { - ASSERT(nsegs > tb->nsegs); - sys_memcpy(eseg->segtab, old_segtab, tb->nsegs*sizeof(struct segment*)); - } + case NSEG_1: nsegs = NSEG_2; break; + default: nsegs = seg_ix + NSEG_INC; break; + } + ASSERT(nsegs > tb->nsegs); + est = (struct ext_segtab*) erts_db_alloc(ERTS_ALC_T_DB_SEG, + (DbTable *) tb, + SIZEOF_EXT_SEGTAB(nsegs)); + est->nsegs = nsegs; + est->prev_segtab = old_segtab; + est->prev_nsegs = tb->nsegs; + sys_memcpy(est->segtab, old_segtab, tb->nsegs*sizeof(struct segment*)); #ifdef DEBUG - sys_memset(&eseg->segtab[seg_ix], 0, (nsegs-seg_ix)*sizeof(struct segment*)); + sys_memset(&est->segtab[seg_ix], 0, (nsegs-seg_ix)*sizeof(struct segment*)); #endif - eseg->segtab[seg_ix] = &eseg->s; - return eseg; + return est; } /* Extend table with one new segment */ -static int alloc_seg(DbTableHash *tb) +static void alloc_seg(DbTableHash *tb) { - int seg_ix = tb->nslots >> SEGSZ_EXP; - - if (seg_ix+1 == tb->nsegs) { /* New segtab needed (extended segment) */ - struct segment** segtab = SEGTAB(tb); - struct ext_segment* seg = alloc_ext_seg(tb, seg_ix, segtab); - if (seg == NULL) return 0; - segtab[seg_ix] = &seg->s; - /* We don't use the new segtab until next call (see "shrink race") */ - } - else { /* Just a new plain segment */ - struct segment** segtab; - if (seg_ix == tb->nsegs) { /* Time to start use segtab from last call */ - struct ext_segment* eseg; - eseg = (struct ext_segment*) SEGTAB(tb)[seg_ix-1]; - MY_ASSERT(eseg!=NULL && eseg->s.is_ext_segment); - SET_SEGTAB(tb, eseg->segtab); - tb->nsegs = eseg->nsegs; - } - ASSERT(seg_ix < tb->nsegs); - segtab = SEGTAB(tb); - ASSERT(segtab[seg_ix] == NULL); - segtab[seg_ix] = (struct segment*) erts_db_alloc_fnf(ERTS_ALC_T_DB_SEG, - (DbTable *) tb, - sizeof(struct segment)); - if (segtab[seg_ix] == NULL) return 0; - sys_memset(segtab[seg_ix], 0, sizeof(struct segment)); - } - tb->nslots += SEGSZ; - return 1; + int seg_ix = SLOT_IX_TO_SEG_IX(tb->nslots); + struct segment** segtab; + + ASSERT(seg_ix > 0); + if (seg_ix == tb->nsegs) { /* New segtab needed */ + struct ext_segtab* est = alloc_ext_segtab(tb, seg_ix); + SET_SEGTAB(tb, est->segtab); + tb->nsegs = est->nsegs; + } + ASSERT(seg_ix < tb->nsegs); + segtab = SEGTAB(tb); + segtab[seg_ix] = (struct segment*) erts_db_alloc(ERTS_ALC_T_DB_SEG, + (DbTable *) tb, + SIZEOF_SEGMENT(EXT_SEGSZ)); + sys_memset(segtab[seg_ix], 0, SIZEOF_SEGMENT(EXT_SEGSZ)); + tb->nslots += EXT_SEGSZ; +} + +#ifdef ERTS_SMP +static void dealloc_ext_segtab(void* lop_data) +{ + struct ext_segtab* est = (struct ext_segtab*) lop_data; + + erts_free(ERTS_ALC_T_DB_SEG, est); } +#endif /* Shrink table by freeing the top segment ** free_records: 1=free any records in segment, 0=assume segment is empty */ static int free_seg(DbTableHash *tb, int free_records) { - const int seg_ix = (tb->nslots >> SEGSZ_EXP) - 1; + const int seg_ix = SLOT_IX_TO_SEG_IX(tb->nslots) - 1; struct segment** const segtab = SEGTAB(tb); - struct ext_segment* const top = (struct ext_segment*) segtab[seg_ix]; - int bytes; + struct segment* const segp = segtab[seg_ix]; + Uint seg_sz; int nrecords = 0; - ASSERT(top != NULL); + ASSERT(segp != NULL); #ifndef DEBUG if (free_records) #endif { - int i; - for (i=0; i<SEGSZ; ++i) { - HashDbTerm* p = top->s.buckets[i]; + int i = (seg_ix == 0) ? FIRST_SEGSZ : EXT_SEGSZ; + while (i--) { + HashDbTerm* p = segp->buckets[i]; while(p != 0) { HashDbTerm* nxt = p->next; ASSERT(free_records); /* segment not empty as assumed? */ @@ -2507,55 +2478,46 @@ static int free_seg(DbTableHash *tb, int free_records) } } } - - /* The "shrink race": - * We must avoid deallocating an extended segment while its segtab may - * still be used by other threads. - * The trick is to stop use a segtab one call earlier. That is, stop use - * a segtab when the segment above it is deallocated. When the segtab is - * later deallocated, it has not been used for a very long time. - * It is even theoretically safe as we have by then rehashed the entire - * segment, seizing *all* locks, so there cannot exist any retarded threads - * still hanging in BUCKET macro with an old segtab pointer. - * For this to work, we must of course allocate a new segtab one call - * earlier in alloc_seg() as well. And this is also the reason why - * the minimum size of the first segtab is 2 and not 1 (NSEG_1). - */ - if (seg_ix == tb->nsegs-1 || seg_ix==0) { /* Dealloc extended segment */ - MY_ASSERT(top->s.is_ext_segment); - ASSERT(segtab != top->segtab || seg_ix==0); - bytes = SIZEOF_EXTSEG(top->nsegs); - } - else { /* Dealloc plain segment */ - struct ext_segment* newtop = (struct ext_segment*) segtab[seg_ix-1]; - MY_ASSERT(!top->s.is_ext_segment); - - if (segtab == newtop->segtab) { /* New top segment is extended */ - MY_ASSERT(newtop->s.is_ext_segment); - if (newtop->prev_segtab != NULL) { - /* Time to use a smaller segtab */ - SET_SEGTAB(tb, newtop->prev_segtab); - tb->nsegs = seg_ix; - ASSERT(tb->nsegs == EXTSEG(SEGTAB(tb))->nsegs); - } - else { - ASSERT(NSEG_1 > 2 && seg_ix==1); - } - } - bytes = sizeof(struct segment); + if (seg_ix >= NSEG_1) { + struct ext_segtab* est = ErtsContainerStruct_(segtab,struct ext_segtab,segtab); + + if (seg_ix == est->prev_nsegs) { /* Dealloc extended segtab */ + ASSERT(est->prev_segtab != NULL); + SET_SEGTAB(tb, est->prev_segtab); + tb->nsegs = est->prev_nsegs; + +#ifdef ERTS_SMP + if (!tb->common.is_thread_safe) { + /* + * Table is doing a graceful shrink operation and we must avoid + * deallocating this segtab while it may still be read by other + * threads. Schedule deallocation with thread progress to make + * sure no lingering threads are still hanging in BUCKET macro + * with an old segtab pointer. + */ + Uint sz = SIZEOF_EXT_SEGTAB(est->nsegs); + ASSERT(sz == ERTS_ALC_DBG_BLK_SZ(est)); + ERTS_DB_ALC_MEM_UPDATE_(tb, sz, 0); + erts_schedule_thr_prgr_later_cleanup_op(dealloc_ext_segtab, + est, + &est->lop, + sz); + } + else +#endif + erts_db_free(ERTS_ALC_T_DB_SEG, (DbTable*)tb, est, + SIZEOF_EXT_SEGTAB(est->nsegs)); + } } + seg_sz = (seg_ix == 0) ? FIRST_SEGSZ : EXT_SEGSZ; + erts_db_free(ERTS_ALC_T_DB_SEG, (DbTable *)tb, segp, SIZEOF_SEGMENT(seg_sz)); - erts_db_free(ERTS_ALC_T_DB_SEG, (DbTable *)tb, - (void*)top, bytes); #ifdef DEBUG - if (seg_ix > 0) { - segtab[seg_ix] = NULL; - } else { - SET_SEGTAB(tb, NULL); - } + if (seg_ix < tb->nsegs) + SEGTAB(tb)[seg_ix] = NULL; #endif - tb->nslots -= SEGSZ; + tb->nslots -= seg_sz; ASSERT(tb->nslots >= 0); return nrecords; } @@ -2604,104 +2566,111 @@ static Eterm build_term_list(Process* p, HashDbTerm* ptr1, HashDbTerm* ptr2, static ERTS_INLINE int begin_resizing(DbTableHash* tb) { +#ifdef ERTS_SMP if (DB_USING_FINE_LOCKING(tb)) - return !erts_smp_atomic_xchg_acqb(&tb->is_resizing, 1); - else { - if (erts_smp_atomic_read_nob(&tb->is_resizing)) - return 0; - erts_smp_atomic_set_nob(&tb->is_resizing, 1); - return 1; - } + return !erts_atomic_xchg_acqb(&tb->is_resizing, 1); + else + ERTS_LC_ASSERT(erts_lc_rwmtx_is_rwlocked(&tb->common.rwlock)); +#endif + return 1; } static ERTS_INLINE void done_resizing(DbTableHash* tb) { +#ifdef ERTS_SMP if (DB_USING_FINE_LOCKING(tb)) - erts_smp_atomic_set_relb(&tb->is_resizing, 0); - else - erts_smp_atomic_set_nob(&tb->is_resizing, 0); + erts_atomic_set_relb(&tb->is_resizing, 0); +#endif } -/* Grow table with one new bucket. +/* Grow table with one or more new buckets. ** Allocate new segment if needed. */ -static void grow(DbTableHash* tb, int nactive) +static void grow(DbTableHash* tb, int nitems) { HashDbTerm** pnext; HashDbTerm** to_pnext; HashDbTerm* p; erts_smp_rwmtx_t* lck; - int from_ix; + int nactive; + int from_ix, to_ix; int szm; + int loop_limit = 5; - if (!begin_resizing(tb)) - return; /* already in progress */ - if (NACTIVE(tb) != nactive) { - goto abort; /* already done (race) */ - } - - /* Ensure that the slot nactive exists */ - if (nactive == tb->nslots) { - /* Time to get a new segment */ - ASSERT((nactive & SEGSZ_MASK) == 0); - if (!alloc_seg(tb)) goto abort; - } - ASSERT(nactive < tb->nslots); + do { + if (!begin_resizing(tb)) + return; /* already in progress */ + nactive = NACTIVE(tb); + if (nitems <= GROW_LIMIT(nactive)) { + goto abort; /* already done (race) */ + } - szm = erts_smp_atomic_read_nob(&tb->szm); - if (nactive <= szm) { - from_ix = nactive & (szm >> 1); - } else { - ASSERT(nactive == szm+1); - from_ix = 0; - szm = (szm<<1) | 1; - } + /* Ensure that the slot nactive exists */ + if (nactive == tb->nslots) { + /* Time to get a new segment */ + ASSERT(((nactive-FIRST_SEGSZ) & EXT_SEGSZ_MASK) == 0); + alloc_seg(tb); + } + ASSERT(nactive < tb->nslots); - lck = WLOCK_HASH(tb, from_ix); - /* Now a final double check (with the from_ix lock held) - * that we did not get raced by a table fixer. - */ - if (IS_FIXED(tb)) { - WUNLOCK_HASH(lck); - goto abort; - } - erts_smp_atomic_inc_nob(&tb->nactive); - if (from_ix == 0) { - if (DB_USING_FINE_LOCKING(tb)) - erts_smp_atomic_set_relb(&tb->szm, szm); - else - erts_smp_atomic_set_nob(&tb->szm, szm); - } - done_resizing(tb); + szm = erts_smp_atomic_read_nob(&tb->szm); + if (nactive <= szm) { + from_ix = nactive & (szm >> 1); + } else { + ASSERT(nactive == szm+1); + from_ix = 0; + szm = (szm<<1) | 1; + } + to_ix = nactive; + + lck = WLOCK_HASH(tb, from_ix); + ERTS_SMP_ASSERT(lck == GET_LOCK_MAYBE(tb,to_ix)); + /* Now a final double check (with the from_ix lock held) + * that we did not get raced by a table fixer. + */ + if (IS_FIXED(tb)) { + WUNLOCK_HASH(lck); + goto abort; + } + erts_smp_atomic_set_nob(&tb->nactive, ++nactive); + if (from_ix == 0) { + if (DB_USING_FINE_LOCKING(tb)) + erts_smp_atomic_set_relb(&tb->szm, szm); + else + erts_smp_atomic_set_nob(&tb->szm, szm); + } + done_resizing(tb); + + /* Finally, let's split the bucket. We try to do it in a smart way + to keep link order and avoid unnecessary updates of next-pointers */ + pnext = &BUCKET(tb, from_ix); + p = *pnext; + to_pnext = &BUCKET(tb, to_ix); + while (p != NULL) { + if (p->hvalue == INVALID_HASH) { /* rare but possible with fine locking */ + *pnext = p->next; + free_term(tb, p); + p = *pnext; + } + else { + int ix = p->hvalue & szm; + if (ix != from_ix) { + ASSERT(ix == (from_ix ^ ((szm+1)>>1))); + *to_pnext = p; + /* Swap "from" and "to": */ + from_ix = ix; + to_pnext = pnext; + } + pnext = &p->next; + p = *pnext; + } + } + *to_pnext = NULL; + WUNLOCK_HASH(lck); - /* Finally, let's split the bucket. We try to do it in a smart way - to keep link order and avoid unnecessary updates of next-pointers */ - pnext = &BUCKET(tb, from_ix); - p = *pnext; - to_pnext = &BUCKET(tb, nactive); - while (p != NULL) { - if (p->hvalue == INVALID_HASH) { /* rare but possible with fine locking */ - *pnext = p->next; - free_term(tb, p); - p = *pnext; - } - else { - int ix = p->hvalue & szm; - if (ix != from_ix) { - ASSERT(ix == (from_ix ^ ((szm+1)>>1))); - *to_pnext = p; - /* Swap "from" and "to": */ - from_ix = ix; - to_pnext = pnext; - } - pnext = &p->next; - p = *pnext; - } - } - *to_pnext = NULL; + }while (--loop_limit && nitems > GROW_LIMIT(nactive)); - WUNLOCK_HASH(lck); return; abort: @@ -2712,60 +2681,78 @@ abort: /* Shrink table by joining top bucket. ** Remove top segment if it gets empty. */ -static void shrink(DbTableHash* tb, int nactive) -{ - if (!begin_resizing(tb)) - return; /* already in progress */ - if (NACTIVE(tb) == nactive) { - erts_smp_rwmtx_t* lck; - int src_ix = nactive - 1; - int low_szm = erts_smp_atomic_read_nob(&tb->szm) >> 1; - int dst_ix = src_ix & low_szm; - - ASSERT(dst_ix < src_ix); - ASSERT(nactive > SEGSZ); - lck = WLOCK_HASH(tb, dst_ix); - /* Double check for racing table fixers */ - if (!IS_FIXED(tb)) { - HashDbTerm** src_bp = &BUCKET(tb, src_ix); - HashDbTerm** dst_bp = &BUCKET(tb, dst_ix); - HashDbTerm** bp = src_bp; - - /* Q: Why join lists by appending "dst" at the end of "src"? - A: Must step through "src" anyway to purge pseudo deleted. */ - while(*bp != NULL) { - if ((*bp)->hvalue == INVALID_HASH) { - HashDbTerm* deleted = *bp; - *bp = deleted->next; - free_term(tb, deleted); - } else { - bp = &(*bp)->next; - } - } - *bp = *dst_bp; - *dst_bp = *src_bp; - *src_bp = NULL; - - erts_smp_atomic_set_nob(&tb->nactive, src_ix); - if (dst_ix == 0) { - erts_smp_atomic_set_relb(&tb->szm, low_szm); - } - WUNLOCK_HASH(lck); - - if (tb->nslots - src_ix >= SEGSZ) { - free_seg(tb, 0); - } - } - else { - WUNLOCK_HASH(lck); - } +static void shrink(DbTableHash* tb, int nitems) +{ + HashDbTerm** src_bp; + HashDbTerm** dst_bp; + HashDbTerm** bp; + erts_smp_rwmtx_t* lck; + int src_ix, dst_ix, low_szm; + int nactive; + int loop_limit = 5; - } - /*else already done */ + do { + if (!begin_resizing(tb)) + return; /* already in progress */ + nactive = NACTIVE(tb); + if (!(nactive > FIRST_SEGSZ && nitems < SHRINK_LIMIT(nactive))) { + goto abort; /* already done (race) */ + } + src_ix = nactive - 1; + low_szm = erts_smp_atomic_read_nob(&tb->szm) >> 1; + dst_ix = src_ix & low_szm; + + ASSERT(dst_ix < src_ix); + ASSERT(nactive > FIRST_SEGSZ); + lck = WLOCK_HASH(tb, dst_ix); + ERTS_SMP_ASSERT(lck == GET_LOCK_MAYBE(tb,src_ix)); + /* Double check for racing table fixers */ + if (IS_FIXED(tb)) { + WUNLOCK_HASH(lck); + goto abort; + } + + src_bp = &BUCKET(tb, src_ix); + dst_bp = &BUCKET(tb, dst_ix); + bp = src_bp; + + /* + * We join lists by appending "dst" at the end of "src" + * as we must step through "src" anyway to purge pseudo deleted. + */ + while(*bp != NULL) { + if ((*bp)->hvalue == INVALID_HASH) { + HashDbTerm* deleted = *bp; + *bp = deleted->next; + free_term(tb, deleted); + } else { + bp = &(*bp)->next; + } + } + *bp = *dst_bp; + *dst_bp = *src_bp; + *src_bp = NULL; + + nactive = src_ix; + erts_smp_atomic_set_nob(&tb->nactive, nactive); + if (dst_ix == 0) { + erts_smp_atomic_set_relb(&tb->szm, low_szm); + } + WUNLOCK_HASH(lck); + + if (tb->nslots - src_ix >= EXT_SEGSZ) { + free_seg(tb, 0); + } + done_resizing(tb); + + } while (--loop_limit + && nactive > FIRST_SEGSZ && nitems < SHRINK_LIMIT(nactive)); + return; + +abort: done_resizing(tb); } - /* Search a list of tuples for a matching key */ static HashDbTerm* search_list(DbTableHash* tb, Eterm key, @@ -2931,8 +2918,8 @@ db_finalize_dbterm_hash(int cret, DbUpdateHandle* handle) WUNLOCK_HASH(lck); nactive = NACTIVE(tb); - if (nitems > nactive * (CHAIN_LEN + 1) && !IS_FIXED(tb)) { - grow(tb, nactive); + if (nitems > GROW_LIMIT(nactive) && !IS_FIXED(tb)) { + grow(tb, nitems); } } else { WUNLOCK_HASH(lck); @@ -3016,6 +3003,51 @@ void db_calc_stats_hash(DbTableHash* tb, DbHashStats* stats) stats->std_dev_expected = sqrt(stats->avg_chain_len * (1 - 1.0/NACTIVE(tb))); stats->kept_items = kept_items; } + +/* For testing only */ +Eterm erts_ets_hash_sizeof_ext_segtab(void) +{ + return make_small(((SIZEOF_EXT_SEGTAB(0)-1) / sizeof(UWord)) + 1); +} +/* For testing only */ +Eterm erts_ets_hash_get_memstate(Process* p, DbTableHash* tb) +{ + Eterm seg_cnt; + while (!begin_resizing(tb)) + /*spinn*/; + + seg_cnt = make_small(SLOT_IX_TO_SEG_IX(tb->nslots)); + done_resizing(tb); + return seg_cnt; +} +/* For testing only */ +Eterm erts_ets_hash_restore_memstate(DbTableHash* tb, Eterm memstate) +{ + int seg_cnt, target; + + if (!is_small(memstate)) + return make_small(__LINE__); + + target = signed_val(memstate); + if (target < 1) + return make_small(__LINE__); + while (1) { + while (!begin_resizing(tb)) + /*spin*/; + seg_cnt = SLOT_IX_TO_SEG_IX(tb->nslots); + done_resizing(tb); + + if (target == seg_cnt) + return am_ok; + if (IS_FIXED(tb)) + return make_small(__LINE__); + if (target < seg_cnt) + shrink(tb, 0); + else + grow(tb, INT_MAX); + } +} + #ifdef HARDDEBUG void db_check_table_hash(DbTable *tbl) @@ -3024,7 +3056,7 @@ void db_check_table_hash(DbTable *tbl) HashDbTerm* list; int j; - for (j = 0; j < tb->nactive; j++) { + for (j = 0; j < NACTIVE(tb); j++) { if ((list = BUCKET(tb,j)) != 0) { while (list != 0) { if (!is_tuple(make_tuple(list->dbterm.tpl))) { |