1 /*

     2  * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #include "precompiled.hpp"

    26 #include "libadt/dict.hpp"

    27 

    28 // Dictionaries - An Abstract Data Type

    29 

    30 // %%%%% includes not needed with AVM framework - Ungar

    31 

    32 #include <assert.h>

    33 

    34 //------------------------------data-----------------------------------------

    35 // String hash tables

    36 #define MAXID 20

    37 static uint8_t initflag = 0;       // True after 1st initialization

    38 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};

    39 static short xsum[MAXID];

    40 

    41 //------------------------------bucket---------------------------------------

    42 class bucket : public ResourceObj {

    43 public:

    44   uint _cnt, _max;              // Size of bucket

    45   void **_keyvals;              // Array of keys and values

    46 };

    47 

    48 //------------------------------Dict-----------------------------------------

    49 // The dictionary is kept has a hash table.  The hash table is a even power

    50 // of two, for nice modulo operations.  Each bucket in the hash table points

    51 // to a linear list of key-value pairs; each key & value is just a (void *).

    52 // The list starts with a count.  A hash lookup finds the list head, then a

    53 // simple linear scan finds the key.  If the table gets too full, it's

    54 // doubled in size; the total amount of EXTRA times all hash functions are

    55 // computed for the doubling is no more than the current size - thus the

    56 // doubling in size costs no more than a constant factor in speed.

    57 Dict::Dict(CmpKey initcmp, Hash inithash) : _hash(inithash), _cmp(initcmp),

    58   _arena(Thread::current()->resource_area()) {

    59   int i;

    60 

    61   // Precompute table of null character hashes

    62   if( !initflag ) {             // Not initializated yet?

    63     xsum[0] = (1<<shft[0])+1;   // Initialize

    64     for(i=1; i<MAXID; i++) {

    65       xsum[i] = (1<<shft[i])+1+xsum[i-1];

    66     }

    67     initflag = 1;               // Never again

    68   }

    69 

    70   _size = 16;                   // Size is a power of 2

    71   _cnt = 0;                     // Dictionary is empty

    72   _bin = (bucket*)_arena->Amalloc_4(sizeof(bucket)*_size);

    73   memset((void*)_bin,0,sizeof(bucket)*_size);

    74 }

    75 

    76 Dict::Dict(CmpKey initcmp, Hash inithash, Arena *arena, int size)

    77 : _hash(inithash), _cmp(initcmp), _arena(arena) {

    78   int i;

    79 

    80   // Precompute table of null character hashes

    81   if( !initflag ) {             // Not initializated yet?

    82     xsum[0] = (1<<shft[0])+1;   // Initialize

    83     for(i=1; i<MAXID; i++) {

    84       xsum[i] = (1<<shft[i])+1+xsum[i-1];

    85     }

    86     initflag = 1;               // Never again

    87   }

    88 

    89   i=16;

    90   while( i < size ) i <<= 1;

    91   _size = i;                    // Size is a power of 2

    92   _cnt = 0;                     // Dictionary is empty

    93   _bin = (bucket*)_arena->Amalloc_4(sizeof(bucket)*_size);

    94   memset((void*)_bin,0,sizeof(bucket)*_size);

    95 }

    96 

    97 //------------------------------~Dict------------------------------------------

    98 // Delete an existing dictionary.

    99 Dict::~Dict() {

   100   /*

   101   tty->print("~Dict %d/%d: ",_cnt,_size);

   102   for( uint i=0; i < _size; i++) // For complete new table do

   103     tty->print("%d ",_bin[i]._cnt);

   104   tty->print("\n");*/

   105   /*for( uint i=0; i<_size; i++ ) {

   106     FREE_FAST( _bin[i]._keyvals );

   107     } */

   108 }

   109 

   110 //------------------------------Clear----------------------------------------

   111 // Zap to empty; ready for re-use

   112 void Dict::Clear() {

   113   _cnt = 0;                     // Empty contents

   114   for( uint i=0; i<_size; i++ )

   115     _bin[i]._cnt = 0;           // Empty buckets, but leave allocated

   116   // Leave _size & _bin alone, under the assumption that dictionary will

   117   // grow to this size again.

   118 }

   119 

   120 //------------------------------doubhash---------------------------------------

   121 // Double hash table size.  If can't do so, just suffer.  If can, then run

   122 // thru old hash table, moving things to new table.  Note that since hash

   123 // table doubled, exactly 1 new bit is exposed in the mask - so everything

   124 // in the old table ends up on 1 of two lists in the new table; a hi and a

   125 // lo list depending on the value of the bit.

   126 void Dict::doubhash(void) {

   127   uint oldsize = _size;

   128   _size <<= 1;                  // Double in size

   129   _bin = (bucket*)_arena->Arealloc(_bin, sizeof(bucket) * oldsize, sizeof(bucket) * _size);

   130   memset((void*)(&_bin[oldsize]), 0, oldsize * sizeof(bucket));

   131   // Rehash things to spread into new table

   132   for (uint i = 0; i < oldsize; i++) { // For complete OLD table do

   133     bucket *b = &_bin[i];              // Handy shortcut for _bin[i]

   134     if (!b->_keyvals) continue;        // Skip empties fast

   135 

   136     bucket *nb = &_bin[i+oldsize];     // New bucket shortcut

   137     uint j = b->_max;                  // Trim new bucket to nearest power of 2

   138     while (j > b->_cnt) { j >>= 1; }   // above old bucket _cnt

   139     if (!j) { j = 1; }                 // Handle zero-sized buckets

   140     nb->_max = j << 1;

   141     // Allocate worst case space for key-value pairs

   142     nb->_keyvals = (void**)_arena->Amalloc_4(sizeof(void *) * nb->_max * 2);

   143     uint nbcnt = 0;

   144 

   145     for (j = 0; j < b->_cnt; ) {           // Rehash all keys in this bucket

   146       void *key = b->_keyvals[j + j];

   147       if ((_hash(key) & (_size-1)) != i) { // Moving to hi bucket?

   148         nb->_keyvals[nbcnt + nbcnt] = key;

   149         nb->_keyvals[nbcnt + nbcnt + 1] = b->_keyvals[j + j + 1];

   150         nb->_cnt = nbcnt = nbcnt + 1;

   151         b->_cnt--;                         // Remove key/value from lo bucket

   152         b->_keyvals[j + j] = b->_keyvals[b->_cnt + b->_cnt];

   153         b->_keyvals[j + j + 1] = b->_keyvals[b->_cnt + b->_cnt + 1];

   154         // Don't increment j, hash compacted element also.

   155       } else {

   156         j++; // Iterate.

   157       }

   158     } // End of for all key-value pairs in bucket

   159   } // End of for all buckets

   160 }

   161 

   162 //------------------------------Dict-----------------------------------------

   163 // Deep copy a dictionary.

   164 Dict::Dict( const Dict &d ) : _size(d._size), _cnt(d._cnt), _hash(d._hash),_cmp(d._cmp), _arena(d._arena) {

   165   _bin = (bucket*)_arena->Amalloc_4(sizeof(bucket)*_size);

   166   memcpy( (void*)_bin, (void*)d._bin, sizeof(bucket)*_size );

   167   for( uint i=0; i<_size; i++ ) {

   168     if( !_bin[i]._keyvals ) continue;

   169     _bin[i]._keyvals=(void**)_arena->Amalloc_4( sizeof(void *)*_bin[i]._max*2);

   170     memcpy( _bin[i]._keyvals, d._bin[i]._keyvals,_bin[i]._cnt*2*sizeof(void*));

   171   }

   172 }

   173 

   174 //------------------------------Dict-----------------------------------------

   175 // Deep copy a dictionary.

   176 Dict &Dict::operator =( const Dict &d ) {

   177   if( _size < d._size ) {       // If must have more buckets

   178     _arena = d._arena;

   179     _bin = (bucket*)_arena->Arealloc( _bin, sizeof(bucket)*_size, sizeof(bucket)*d._size );

   180     memset( (void*)(&_bin[_size]), 0, (d._size-_size)*sizeof(bucket) );

   181     _size = d._size;

   182   }

   183   uint i;

   184   for( i=0; i<_size; i++ ) // All buckets are empty

   185     _bin[i]._cnt = 0;           // But leave bucket allocations alone

   186   _cnt = d._cnt;

   187   *(Hash*)(&_hash) = d._hash;

   188   *(CmpKey*)(&_cmp) = d._cmp;

   189   for( i=0; i<_size; i++ ) {

   190     bucket *b = &d._bin[i];     // Shortcut to source bucket

   191     for( uint j=0; j<b->_cnt; j++ )

   192       Insert( b->_keyvals[j+j], b->_keyvals[j+j+1] );

   193   }

   194   return *this;

   195 }

   196 

   197 //------------------------------Insert----------------------------------------

   198 // Insert or replace a key/value pair in the given dictionary.  If the

   199 // dictionary is too full, it's size is doubled.  The prior value being

   200 // replaced is returned (NULL if this is a 1st insertion of that key).  If

   201 // an old value is found, it's swapped with the prior key-value pair on the

   202 // list.  This moves a commonly searched-for value towards the list head.

   203 void *Dict::Insert(void *key, void *val, bool replace) {

   204   uint hash = _hash( key );     // Get hash key

   205   uint i = hash & (_size-1);    // Get hash key, corrected for size

   206   bucket *b = &_bin[i];         // Handy shortcut

   207   for( uint j=0; j<b->_cnt; j++ ) {

   208     if( !_cmp(key,b->_keyvals[j+j]) ) {

   209       if (!replace) {

   210         return b->_keyvals[j+j+1];

   211       } else {

   212         void *prior = b->_keyvals[j+j+1];

   213         b->_keyvals[j+j  ] = key;       // Insert current key-value

   214         b->_keyvals[j+j+1] = val;

   215         return prior;           // Return prior

   216       }

   217     }

   218   }

   219   if( ++_cnt > _size ) {        // Hash table is full

   220     doubhash();                 // Grow whole table if too full

   221     i = hash & (_size-1);       // Rehash

   222     b = &_bin[i];               // Handy shortcut

   223   }

   224   if( b->_cnt == b->_max ) {    // Must grow bucket?

   225     if( !b->_keyvals ) {

   226       b->_max = 2;              // Initial bucket size

   227       b->_keyvals = (void**)_arena->Amalloc_4(sizeof(void*) * b->_max * 2);

   228     } else {

   229       b->_keyvals = (void**)_arena->Arealloc(b->_keyvals, sizeof(void*) * b->_max * 2, sizeof(void*) * b->_max * 4);

   230       b->_max <<= 1;            // Double bucket

   231     }

   232   }

   233   b->_keyvals[b->_cnt+b->_cnt  ] = key;

   234   b->_keyvals[b->_cnt+b->_cnt+1] = val;

   235   b->_cnt++;

   236   return NULL;                  // Nothing found prior

   237 }

   238 

   239 //------------------------------Delete---------------------------------------

   240 // Find & remove a value from dictionary. Return old value.

   241 void *Dict::Delete(void *key) {

   242   uint i = _hash( key ) & (_size-1);    // Get hash key, corrected for size

   243   bucket *b = &_bin[i];         // Handy shortcut

   244   for( uint j=0; j<b->_cnt; j++ )

   245     if( !_cmp(key,b->_keyvals[j+j]) ) {

   246       void *prior = b->_keyvals[j+j+1];

   247       b->_cnt--;                // Remove key/value from lo bucket

   248       b->_keyvals[j+j  ] = b->_keyvals[b->_cnt+b->_cnt  ];

   249       b->_keyvals[j+j+1] = b->_keyvals[b->_cnt+b->_cnt+1];

   250       _cnt--;                   // One less thing in table

   251       return prior;

   252     }

   253   return NULL;

   254 }

   255 

   256 //------------------------------FindDict-------------------------------------

   257 // Find a key-value pair in the given dictionary.  If not found, return NULL.

   258 // If found, move key-value pair towards head of list.

   259 void *Dict::operator [](const void *key) const {

   260   uint i = _hash( key ) & (_size-1);    // Get hash key, corrected for size

   261   bucket *b = &_bin[i];         // Handy shortcut

   262   for( uint j=0; j<b->_cnt; j++ )

   263     if( !_cmp(key,b->_keyvals[j+j]) )

   264       return b->_keyvals[j+j+1];

   265   return NULL;

   266 }

   267 

   268 //------------------------------CmpDict--------------------------------------

   269 // CmpDict compares two dictionaries; they must have the same keys (their

   270 // keys must match using CmpKey) and they must have the same values (pointer

   271 // comparison).  If so 1 is returned, if not 0 is returned.

   272 int32_t Dict::operator ==(const Dict &d2) const {

   273   if( _cnt != d2._cnt ) return 0;

   274   if( _hash != d2._hash ) return 0;

   275   if( _cmp != d2._cmp ) return 0;

   276   for( uint i=0; i < _size; i++) {      // For complete hash table do

   277     bucket *b = &_bin[i];       // Handy shortcut

   278     if( b->_cnt != d2._bin[i]._cnt ) return 0;

   279     if( memcmp(b->_keyvals, d2._bin[i]._keyvals, b->_cnt*2*sizeof(void*) ) )

   280       return 0;                 // Key-value pairs must match

   281   }

   282   return 1;                     // All match, is OK

   283 }

   284 

   285 //------------------------------print------------------------------------------

   286 // Handier print routine

   287 void Dict::print() {

   288   DictI i(this); // Moved definition in iterator here because of g++.

   289   tty->print("Dict@" INTPTR_FORMAT "[%d] = {", p2i(this), _cnt);

   290   for( ; i.test(); ++i ) {

   291     tty->print("(" INTPTR_FORMAT "," INTPTR_FORMAT "),", p2i(i._key), p2i(i._value));

   292   }

   293   tty->print_cr("}");

   294 }

   295 

   296 //------------------------------Hashing Functions----------------------------

   297 // Convert string to hash key.  This algorithm implements a universal hash

   298 // function with the multipliers frozen (ok, so it's not universal).  The

   299 // multipliers (and allowable characters) are all odd, so the resultant sum

   300 // is odd - guaranteed not divisible by any power of two, so the hash tables

   301 // can be any power of two with good results.  Also, I choose multipliers

   302 // that have only 2 bits set (the low is always set to be odd) so

   303 // multiplication requires only shifts and adds.  Characters are required to

   304 // be in the range 0-127 (I double & add 1 to force oddness).  Keys are

   305 // limited to MAXID characters in length.  Experimental evidence on 150K of

   306 // C text shows excellent spreading of values for any size hash table.

   307 int hashstr(const void *t) {

   308   register char c, k = 0;

   309   register int32_t sum = 0;

   310   register const char *s = (const char *)t;

   311 

   312   while( ((c = *s++) != '\0') && (k < MAXID-1) ) { // Get characters till null or MAXID-1

   313     c = (c<<1)+1;               // Characters are always odd!

   314     sum += c + (c<<shft[k++]);  // Universal hash function

   315   }

   316   return (int)((sum+xsum[k]) >> 1); // Hash key, un-modulo'd table size

   317 }

   318 

   319 //------------------------------hashptr--------------------------------------

   320 // Slimey cheap hash function; no guaranteed performance.  Better than the

   321 // default for pointers, especially on MS-DOS machines.

   322 int hashptr(const void *key) {

   323   return ((intptr_t)key >> 2);

   324 }

   325 

   326 // Slimey cheap hash function; no guaranteed performance.

   327 int hashkey(const void *key) {

   328   return (intptr_t)key;

   329 }

   330 

   331 //------------------------------Key Comparator Functions---------------------

   332 int32_t cmpstr(const void *k1, const void *k2) {

   333   return strcmp((const char *)k1,(const char *)k2);

   334 }

   335 

   336 // Cheap key comparator.

   337 int32_t cmpkey(const void *key1, const void *key2) {

   338   if (key1 == key2) return 0;

   339   intptr_t delta = (intptr_t)key1 - (intptr_t)key2;

   340   if (delta > 0) return 1;

   341   return -1;

   342 }

   343 

   344 //=============================================================================

   345 //------------------------------reset------------------------------------------

   346 // Create an iterator and initialize the first variables.

   347 void DictI::reset( const Dict *dict ) {

   348   _d = dict;                    // The dictionary

   349   _i = (uint)-1;                // Before the first bin

   350   _j = 0;                       // Nothing left in the current bin

   351   ++(*this);                    // Step to first real value

   352 }

   353 

   354 //------------------------------next-------------------------------------------

   355 // Find the next key-value pair in the dictionary, or return a NULL key and

   356 // value.

   357 void DictI::operator ++(void) {

   358   if( _j-- ) {                  // Still working in current bin?

   359     _key   = _d->_bin[_i]._keyvals[_j+_j];

   360     _value = _d->_bin[_i]._keyvals[_j+_j+1];

   361     return;

   362   }

   363 

   364   while( ++_i < _d->_size ) {   // Else scan for non-zero bucket

   365     _j = _d->_bin[_i]._cnt;

   366     if( !_j ) continue;

   367     _j--;

   368     _key   = _d->_bin[_i]._keyvals[_j+_j];

   369     _value = _d->_bin[_i]._keyvals[_j+_j+1];

   370     return;

   371   }

   372   _key = _value = NULL;

   373 }