Mercurial > hg > truffle
view src/share/vm/libadt/dict.cpp @ 20543:e7d0505c8a30
8059758: Footprint regressions with JDK-8038423
Summary: Changes in JDK-8038423 always initialize (zero out) virtual memory used for auxiliary data structures. This causes a footprint regression for G1 in startup benchmarks. This is because they do not touch that memory at all, so the operating system does not actually commit these pages. The fix is to, if the initialization value of the data structures matches the default value of just committed memory (=0), do not do anything.
Reviewed-by: jwilhelm, brutisso
author | tschatzl |
---|---|
date | Fri, 10 Oct 2014 15:51:58 +0200 |
parents | 78bbf4d43a14 |
children |
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/* * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "precompiled.hpp" #include "libadt/dict.hpp" #include "memory/allocation.inline.hpp" #include "memory/resourceArea.hpp" #include "runtime/thread.hpp" // Dictionaries - An Abstract Data Type // %%%%% includes not needed with AVM framework - Ungar // #include "port.hpp" //IMPLEMENTATION // #include "dict.hpp" #include <assert.h> PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC // The iostream is not needed and it gets confused for gcc by the // define of bool. // // #include <iostream.h> //------------------------------data----------------------------------------- // String hash tables #define MAXID 20 static byte initflag = 0; // True after 1st initialization static const char shft[MAXID] = {1,2,3,4,5,6,7,1,2,3,4,5,6,7,1,2,3,4,5,6}; static short xsum[MAXID]; //------------------------------bucket--------------------------------------- class bucket : public ResourceObj { public: uint _cnt, _max; // Size of bucket void **_keyvals; // Array of keys and values }; //------------------------------Dict----------------------------------------- // The dictionary is kept has a hash table. The hash table is a even power // of two, for nice modulo operations. Each bucket in the hash table points // to a linear list of key-value pairs; each key & value is just a (void *). // The list starts with a count. A hash lookup finds the list head, then a // simple linear scan finds the key. If the table gets too full, it's // doubled in size; the total amount of EXTRA times all hash functions are // computed for the doubling is no more than the current size - thus the // doubling in size costs no more than a constant factor in speed. Dict::Dict(CmpKey initcmp, Hash inithash) : _hash(inithash), _cmp(initcmp), _arena(Thread::current()->resource_area()) { int i; // Precompute table of null character hashes if( !initflag ) { // Not initializated yet? xsum[0] = (1<<shft[0])+1; // Initialize for(i=1; i<MAXID; i++) { xsum[i] = (1<<shft[i])+1+xsum[i-1]; } initflag = 1; // Never again } _size = 16; // Size is a power of 2 _cnt = 0; // Dictionary is empty _bin = (bucket*)_arena->Amalloc_4(sizeof(bucket)*_size); memset(_bin,0,sizeof(bucket)*_size); } Dict::Dict(CmpKey initcmp, Hash inithash, Arena *arena, int size) : _hash(inithash), _cmp(initcmp), _arena(arena) { int i; // Precompute table of null character hashes if( !initflag ) { // Not initializated yet? xsum[0] = (1<<shft[0])+1; // Initialize for(i=1; i<MAXID; i++) { xsum[i] = (1<<shft[i])+1+xsum[i-1]; } initflag = 1; // Never again } i=16; while( i < size ) i <<= 1; _size = i; // Size is a power of 2 _cnt = 0; // Dictionary is empty _bin = (bucket*)_arena->Amalloc_4(sizeof(bucket)*_size); memset(_bin,0,sizeof(bucket)*_size); } //------------------------------~Dict------------------------------------------ // Delete an existing dictionary. Dict::~Dict() { /* tty->print("~Dict %d/%d: ",_cnt,_size); for( uint i=0; i < _size; i++) // For complete new table do tty->print("%d ",_bin[i]._cnt); tty->print("\n");*/ /*for( uint i=0; i<_size; i++ ) { FREE_FAST( _bin[i]._keyvals ); } */ } //------------------------------Clear---------------------------------------- // Zap to empty; ready for re-use void Dict::Clear() { _cnt = 0; // Empty contents for( uint i=0; i<_size; i++ ) _bin[i]._cnt = 0; // Empty buckets, but leave allocated // Leave _size & _bin alone, under the assumption that dictionary will // grow to this size again. } //------------------------------doubhash--------------------------------------- // Double hash table size. If can't do so, just suffer. If can, then run // thru old hash table, moving things to new table. Note that since hash // table doubled, exactly 1 new bit is exposed in the mask - so everything // in the old table ends up on 1 of two lists in the new table; a hi and a // lo list depending on the value of the bit. void Dict::doubhash(void) { uint oldsize = _size; _size <<= 1; // Double in size _bin = (bucket*)_arena->Arealloc( _bin, sizeof(bucket)*oldsize, sizeof(bucket)*_size ); memset( &_bin[oldsize], 0, oldsize*sizeof(bucket) ); // Rehash things to spread into new table for( uint i=0; i < oldsize; i++) { // For complete OLD table do bucket *b = &_bin[i]; // Handy shortcut for _bin[i] if( !b->_keyvals ) continue; // Skip empties fast bucket *nb = &_bin[i+oldsize]; // New bucket shortcut uint j = b->_max; // Trim new bucket to nearest power of 2 while( j > b->_cnt ) j >>= 1; // above old bucket _cnt if( !j ) j = 1; // Handle zero-sized buckets nb->_max = j<<1; // Allocate worst case space for key-value pairs nb->_keyvals = (void**)_arena->Amalloc_4( sizeof(void *)*nb->_max*2 ); uint nbcnt = 0; for( j=0; j<b->_cnt; j++ ) { // Rehash all keys in this bucket void *key = b->_keyvals[j+j]; if( (_hash( key ) & (_size-1)) != i ) { // Moving to hi bucket? nb->_keyvals[nbcnt+nbcnt] = key; nb->_keyvals[nbcnt+nbcnt+1] = b->_keyvals[j+j+1]; nb->_cnt = nbcnt = nbcnt+1; b->_cnt--; // Remove key/value from lo bucket b->_keyvals[j+j ] = b->_keyvals[b->_cnt+b->_cnt ]; b->_keyvals[j+j+1] = b->_keyvals[b->_cnt+b->_cnt+1]; j--; // Hash compacted element also } } // End of for all key-value pairs in bucket } // End of for all buckets } //------------------------------Dict----------------------------------------- // Deep copy a dictionary. Dict::Dict( const Dict &d ) : _size(d._size), _cnt(d._cnt), _hash(d._hash),_cmp(d._cmp), _arena(d._arena) { _bin = (bucket*)_arena->Amalloc_4(sizeof(bucket)*_size); memcpy( _bin, d._bin, sizeof(bucket)*_size ); for( uint i=0; i<_size; i++ ) { if( !_bin[i]._keyvals ) continue; _bin[i]._keyvals=(void**)_arena->Amalloc_4( sizeof(void *)*_bin[i]._max*2); memcpy( _bin[i]._keyvals, d._bin[i]._keyvals,_bin[i]._cnt*2*sizeof(void*)); } } //------------------------------Dict----------------------------------------- // Deep copy a dictionary. Dict &Dict::operator =( const Dict &d ) { if( _size < d._size ) { // If must have more buckets _arena = d._arena; _bin = (bucket*)_arena->Arealloc( _bin, sizeof(bucket)*_size, sizeof(bucket)*d._size ); memset( &_bin[_size], 0, (d._size-_size)*sizeof(bucket) ); _size = d._size; } uint i; for( i=0; i<_size; i++ ) // All buckets are empty _bin[i]._cnt = 0; // But leave bucket allocations alone _cnt = d._cnt; *(Hash*)(&_hash) = d._hash; *(CmpKey*)(&_cmp) = d._cmp; for( i=0; i<_size; i++ ) { bucket *b = &d._bin[i]; // Shortcut to source bucket for( uint j=0; j<b->_cnt; j++ ) Insert( b->_keyvals[j+j], b->_keyvals[j+j+1] ); } return *this; } //------------------------------Insert---------------------------------------- // Insert or replace a key/value pair in the given dictionary. If the // dictionary is too full, it's size is doubled. The prior value being // replaced is returned (NULL if this is a 1st insertion of that key). If // an old value is found, it's swapped with the prior key-value pair on the // list. This moves a commonly searched-for value towards the list head. void *Dict::Insert(void *key, void *val, bool replace) { uint hash = _hash( key ); // Get hash key uint i = hash & (_size-1); // Get hash key, corrected for size bucket *b = &_bin[i]; // Handy shortcut for( uint j=0; j<b->_cnt; j++ ) { if( !_cmp(key,b->_keyvals[j+j]) ) { if (!replace) { return b->_keyvals[j+j+1]; } else { void *prior = b->_keyvals[j+j+1]; b->_keyvals[j+j ] = key; // Insert current key-value b->_keyvals[j+j+1] = val; return prior; // Return prior } } } if( ++_cnt > _size ) { // Hash table is full doubhash(); // Grow whole table if too full i = hash & (_size-1); // Rehash b = &_bin[i]; // Handy shortcut } if( b->_cnt == b->_max ) { // Must grow bucket? if( !b->_keyvals ) { b->_max = 2; // Initial bucket size b->_keyvals = (void**)_arena->Amalloc_4(sizeof(void*) * b->_max * 2); } else { b->_keyvals = (void**)_arena->Arealloc(b->_keyvals, sizeof(void*) * b->_max * 2, sizeof(void*) * b->_max * 4); b->_max <<= 1; // Double bucket } } b->_keyvals[b->_cnt+b->_cnt ] = key; b->_keyvals[b->_cnt+b->_cnt+1] = val; b->_cnt++; return NULL; // Nothing found prior } //------------------------------Delete--------------------------------------- // Find & remove a value from dictionary. Return old value. void *Dict::Delete(void *key) { uint i = _hash( key ) & (_size-1); // Get hash key, corrected for size bucket *b = &_bin[i]; // Handy shortcut for( uint j=0; j<b->_cnt; j++ ) if( !_cmp(key,b->_keyvals[j+j]) ) { void *prior = b->_keyvals[j+j+1]; b->_cnt--; // Remove key/value from lo bucket b->_keyvals[j+j ] = b->_keyvals[b->_cnt+b->_cnt ]; b->_keyvals[j+j+1] = b->_keyvals[b->_cnt+b->_cnt+1]; _cnt--; // One less thing in table return prior; } return NULL; } //------------------------------FindDict------------------------------------- // Find a key-value pair in the given dictionary. If not found, return NULL. // If found, move key-value pair towards head of list. void *Dict::operator [](const void *key) const { uint i = _hash( key ) & (_size-1); // Get hash key, corrected for size bucket *b = &_bin[i]; // Handy shortcut for( uint j=0; j<b->_cnt; j++ ) if( !_cmp(key,b->_keyvals[j+j]) ) return b->_keyvals[j+j+1]; return NULL; } //------------------------------CmpDict-------------------------------------- // CmpDict compares two dictionaries; they must have the same keys (their // keys must match using CmpKey) and they must have the same values (pointer // comparison). If so 1 is returned, if not 0 is returned. int32 Dict::operator ==(const Dict &d2) const { if( _cnt != d2._cnt ) return 0; if( _hash != d2._hash ) return 0; if( _cmp != d2._cmp ) return 0; for( uint i=0; i < _size; i++) { // For complete hash table do bucket *b = &_bin[i]; // Handy shortcut if( b->_cnt != d2._bin[i]._cnt ) return 0; if( memcmp(b->_keyvals, d2._bin[i]._keyvals, b->_cnt*2*sizeof(void*) ) ) return 0; // Key-value pairs must match } return 1; // All match, is OK } //------------------------------print------------------------------------------ // Handier print routine void Dict::print() { DictI i(this); // Moved definition in iterator here because of g++. tty->print("Dict@0x%lx[%d] = {", this, _cnt); for( ; i.test(); ++i ) { tty->print("(0x%lx,0x%lx),", i._key, i._value); } tty->print_cr("}"); } //------------------------------Hashing Functions---------------------------- // Convert string to hash key. This algorithm implements a universal hash // function with the multipliers frozen (ok, so it's not universal). The // multipliers (and allowable characters) are all odd, so the resultant sum // is odd - guaranteed not divisible by any power of two, so the hash tables // can be any power of two with good results. Also, I choose multipliers // that have only 2 bits set (the low is always set to be odd) so // multiplication requires only shifts and adds. Characters are required to // be in the range 0-127 (I double & add 1 to force oddness). Keys are // limited to MAXID characters in length. Experimental evidence on 150K of // C text shows excellent spreading of values for any size hash table. int hashstr(const void *t) { register char c, k = 0; register int32 sum = 0; register const char *s = (const char *)t; while( ((c = *s++) != '\0') && (k < MAXID-1) ) { // Get characters till null or MAXID-1 c = (c<<1)+1; // Characters are always odd! sum += c + (c<<shft[k++]); // Universal hash function } return (int)((sum+xsum[k]) >> 1); // Hash key, un-modulo'd table size } //------------------------------hashptr-------------------------------------- // Slimey cheap hash function; no guaranteed performance. Better than the // default for pointers, especially on MS-DOS machines. int hashptr(const void *key) { #ifdef __TURBOC__ return ((intptr_t)key >> 16); #else // __TURBOC__ return ((intptr_t)key >> 2); #endif } // Slimey cheap hash function; no guaranteed performance. int hashkey(const void *key) { return (intptr_t)key; } //------------------------------Key Comparator Functions--------------------- int32 cmpstr(const void *k1, const void *k2) { return strcmp((const char *)k1,(const char *)k2); } // Cheap key comparator. int32 cmpkey(const void *key1, const void *key2) { if (key1 == key2) return 0; intptr_t delta = (intptr_t)key1 - (intptr_t)key2; if (delta > 0) return 1; return -1; } //============================================================================= //------------------------------reset------------------------------------------ // Create an iterator and initialize the first variables. void DictI::reset( const Dict *dict ) { _d = dict; // The dictionary _i = (uint)-1; // Before the first bin _j = 0; // Nothing left in the current bin ++(*this); // Step to first real value } //------------------------------next------------------------------------------- // Find the next key-value pair in the dictionary, or return a NULL key and // value. void DictI::operator ++(void) { if( _j-- ) { // Still working in current bin? _key = _d->_bin[_i]._keyvals[_j+_j]; _value = _d->_bin[_i]._keyvals[_j+_j+1]; return; } while( ++_i < _d->_size ) { // Else scan for non-zero bucket _j = _d->_bin[_i]._cnt; if( !_j ) continue; _j--; _key = _d->_bin[_i]._keyvals[_j+_j]; _value = _d->_bin[_i]._keyvals[_j+_j+1]; return; } _key = _value = NULL; }