diff options
| -rw-r--r-- | hv.c | 50 | ||||
| -rw-r--r-- | hv.h | 11 |
2 files changed, 46 insertions, 15 deletions
@@ -20,6 +20,8 @@ #define PERL_IN_HV_C #include "perl.h" +#define HV_MAX_LENGTH_BEFORE_SPLIT 4 + STATIC HE* S_new_he(pTHX) { @@ -313,7 +315,7 @@ S_hv_fetch_flags(pTHX_ HV *hv, const char *key, I32 klen, I32 lval, int flags) } else HeKFLAGS(entry) = flags; - if (flags) + if (flags & HVhek_ENABLEHVKFLAGS) HvHASKFLAGS_on(hv); } if (flags & HVhek_FREEKEY) @@ -487,7 +489,7 @@ Perl_hv_fetch_ent(pTHX_ HV *hv, SV *keysv, I32 lval, register U32 hash) } else HeKFLAGS(entry) = flags; - if (flags) + if (flags & HVhek_ENABLEHVKFLAGS) HvHASKFLAGS_on(hv); } if (key != keysave) @@ -603,7 +605,7 @@ Perl_hv_store_flags(pTHX_ HV *hv, const char *key, I32 klen, SV *val, register U32 hash, int flags) { register XPVHV* xhv; - register I32 i; + register U32 n_links; register HE *entry; register HE **oentry; @@ -650,9 +652,10 @@ Perl_hv_store_flags(pTHX_ HV *hv, const char *key, I32 klen, SV *val, /* oentry = &(HvARRAY(hv))[hash & (I32) HvMAX(hv)]; */ oentry = &((HE**)xhv->xhv_array)[hash & (I32) xhv->xhv_max]; - i = 1; - for (entry = *oentry; entry; i=0, entry = HeNEXT(entry)) { + n_links = 0; + + for (entry = *oentry; entry; ++n_links, entry = HeNEXT(entry)) { if (HeHASH(entry) != hash) /* strings can't be equal */ continue; if (HeKLEN(entry) != (I32)klen) @@ -719,9 +722,17 @@ Perl_hv_store_flags(pTHX_ HV *hv, const char *key, I32 klen, SV *val, *oentry = entry; xhv->xhv_keys++; /* HvKEYS(hv)++ */ - if (i) { /* initial entry? */ + if (!n_links) { /* initial entry? */ xhv->xhv_fill++; /* HvFILL(hv)++ */ - } else if (xhv->xhv_keys > (IV)xhv->xhv_max /* HvKEYS(hv) > HvMAX(hv) */) { + } else if ((n_links > HV_MAX_LENGTH_BEFORE_SPLIT) + && (!HvREHASH(hv) + || (xhv->xhv_keys > (IV)xhv->xhv_max))) { + /* Use the old HvKEYS(hv) > HvMAX(hv) condition to limit bucket + splits on a rehashed hash, as we're not going to split it again, + and if someone is lucky (evil) enough to get all the keys in one + list they could exhaust our memory as we repeatedly double the + number of buckets on every entry. Linear search feels a less worse + thing to do. */ hsplit(hv); } @@ -763,7 +774,7 @@ Perl_hv_store_ent(pTHX_ HV *hv, SV *keysv, SV *val, U32 hash) XPVHV* xhv; char *key; STRLEN klen; - I32 i; + U32 n_links; HE *entry; HE **oentry; bool is_utf8; @@ -830,9 +841,9 @@ Perl_hv_store_ent(pTHX_ HV *hv, SV *keysv, SV *val, U32 hash) /* oentry = &(HvARRAY(hv))[hash & (I32) HvMAX(hv)]; */ oentry = &((HE**)xhv->xhv_array)[hash & (I32) xhv->xhv_max]; - i = 1; + n_links = 0; entry = *oentry; - for (; entry; i=0, entry = HeNEXT(entry)) { + for (; entry; ++n_links, entry = HeNEXT(entry)) { if (HeHASH(entry) != hash) /* strings can't be equal */ continue; if (HeKLEN(entry) != (I32)klen) @@ -886,10 +897,17 @@ Perl_hv_store_ent(pTHX_ HV *hv, SV *keysv, SV *val, U32 hash) *oentry = entry; xhv->xhv_keys++; /* HvKEYS(hv)++ */ - if (i) { /* initial entry? */ + if (!n_links) { /* initial entry? */ xhv->xhv_fill++; /* HvFILL(hv)++ */ - } else if (xhv->xhv_keys > (IV)xhv->xhv_max /* HvKEYS(hv) > HvMAX(hv) */) { - hsplit(hv); + } else if ((xhv->xhv_keys > (IV)xhv->xhv_max) + || ((n_links > HV_MAX_LENGTH_BEFORE_SPLIT) && !HvREHASH(hv))) { + /* Use only the old HvKEYS(hv) > HvMAX(hv) condition to limit bucket + splits on a rehashed hash, as we're not going to split it again, + and if someone is lucky (evil) enough to get all the keys in one + list they could exhaust our memory as we repeatedly double the + number of buckets on every entry. Linear search feels a less worse + thing to do. */ + hsplit(hv); } return entry; @@ -1511,7 +1529,7 @@ S_hsplit(pTHX_ HV *hv) /* Pick your policy for "hashing isn't working" here: */ - if (longest_chain < 8 || longest_chain * 2 < HvTOTALKEYS(hv) + if (longest_chain <= HV_MAX_LENGTH_BEFORE_SPLIT /* split worked? */ || HvREHASH(hv)) { return; } @@ -1533,7 +1551,6 @@ S_hsplit(pTHX_ HV *hv) xhv->xhv_fill = 0; HvSHAREKEYS_off(hv); HvREHASH_on(hv); - HvHASKFLAGS_on(hv); aep = (HE **) xhv->xhv_array; @@ -2385,6 +2402,9 @@ S_share_hek_flags(pTHX_ const char *str, I32 len, register U32 hash, int flags) if (!(Svp = hv_fetch(PL_strtab, str, len, FALSE))) hv_store(PL_strtab, str, len, Nullsv, hash); + + Can't rehash the shared string table, so not sure if it's worth + counting the number of entries in the linked list */ xhv = (XPVHV*)SvANY(PL_strtab); /* assert(xhv_array != 0) */ @@ -212,6 +212,7 @@ C<SV*>. * is utf8 (including 8 bit keys that were entered as utf8, and need upgrading * when retrieved during iteration. It may still be set when there are no longer * any utf8 keys. + * See HVhek_ENABLEHVKFLAGS for the trigger. */ #define HvHASKFLAGS(hv) (SvFLAGS(hv) & SVphv_HASKFLAGS) #define HvHASKFLAGS_on(hv) (SvFLAGS(hv) |= SVphv_HASKFLAGS) @@ -283,6 +284,16 @@ C<SV*>. * (may change, but Storable is a core module) */ #define HVhek_MASK 0xFF +/* Which flags enable HvHASKFLAGS? Somewhat a hack on a hack, as + HVhek_REHASH is only needed because the rehash flag has to be duplicated + into all keys as hv_iternext has no access to the hash flags. At this + point Storable's tests get upset, because sometimes hashes are "keyed" + and sometimes not, depending on the order of data insertion, and whether + it triggered rehashing. So currently HVhek_REHAS is exempt. +*/ + +#define HVhek_ENABLEHVKFLAGS (HVhek_MASK - HVhek_REHASH) + #define HEK_UTF8(hek) (HEK_FLAGS(hek) & HVhek_UTF8) #define HEK_UTF8_on(hek) (HEK_FLAGS(hek) |= HVhek_UTF8) #define HEK_UTF8_off(hek) (HEK_FLAGS(hek) &= ~HVhek_UTF8) |