collector.cpp00001
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00022 #include "collector.h"
00023
00024 #include "value.h"
00025 #include "internal.h"
00026 #include <limits.h>
00027
00028 #ifndef MAX
00029 #define MAX(a,b) ((a) > (b) ? (a) : (b))
00030 #endif
00031
00032 namespace KJS {
00033
00034
00035 const int MINIMUM_CELL_SIZE = 56;
00036 const int BLOCK_SIZE = (8 * 4096);
00037 const int SPARE_EMPTY_BLOCKS = 2;
00038 const int MIN_ARRAY_SIZE = 14;
00039 const int GROWTH_FACTOR = 2;
00040 const int LOW_WATER_FACTOR = 4;
00041 const int ALLOCATIONS_PER_COLLECTION = 1000;
00042
00043
00044 const int CELL_ARRAY_LENGTH = (MINIMUM_CELL_SIZE / sizeof(double)) + (MINIMUM_CELL_SIZE % sizeof(double) != 0 ? sizeof(double) : 0);
00045 const int CELL_SIZE = CELL_ARRAY_LENGTH * sizeof(double);
00046 const int CELLS_PER_BLOCK = ((BLOCK_SIZE * 8 - sizeof(int) * 8 - sizeof(void *) * 8) / (CELL_SIZE * 8));
00047
00048
00049
00050 struct CollectorCell {
00051 double memory[CELL_ARRAY_LENGTH];
00052 };
00053
00054
00055 struct CollectorBlock {
00056 CollectorCell cells[CELLS_PER_BLOCK];
00057 int usedCells;
00058 CollectorCell *freeList;
00059 };
00060
00061 struct CollectorHeap {
00062 CollectorBlock **blocks;
00063 int numBlocks;
00064 int usedBlocks;
00065 int firstBlockWithPossibleSpace;
00066
00067 CollectorCell **oversizeCells;
00068 int numOversizeCells;
00069 int usedOversizeCells;
00070
00071 int numLiveObjects;
00072 int numAllocationsSinceLastCollect;
00073 };
00074
00075 static CollectorHeap heap = {NULL, 0, 0, 0, NULL, 0, 0, 0, 0};
00076
00077 bool Collector::memoryFull = false;
00078
00079 void* Collector::allocate(size_t s)
00080 {
00081 if (s == 0)
00082 return 0L;
00083
00084
00085 if (++heap.numAllocationsSinceLastCollect >= ALLOCATIONS_PER_COLLECTION) {
00086 collect();
00087 }
00088
00089 if (s > (unsigned)CELL_SIZE) {
00090
00091 if (heap.usedOversizeCells == heap.numOversizeCells) {
00092 heap.numOversizeCells = MAX(MIN_ARRAY_SIZE, heap.numOversizeCells * GROWTH_FACTOR);
00093 heap.oversizeCells = (CollectorCell **)realloc(heap.oversizeCells, heap.numOversizeCells * sizeof(CollectorCell *));
00094 }
00095
00096 void *newCell = malloc(s);
00097 heap.oversizeCells[heap.usedOversizeCells] = (CollectorCell *)newCell;
00098 heap.usedOversizeCells++;
00099 heap.numLiveObjects++;
00100
00101 ((ValueImp *)(newCell))->_flags = 0;
00102 return newCell;
00103 }
00104
00105
00106
00107 CollectorBlock *targetBlock = NULL;
00108
00109 int i;
00110 for (i = heap.firstBlockWithPossibleSpace; i < heap.usedBlocks; i++) {
00111 if (heap.blocks[i]->usedCells < CELLS_PER_BLOCK) {
00112 targetBlock = heap.blocks[i];
00113 break;
00114 }
00115 }
00116
00117 heap.firstBlockWithPossibleSpace = i;
00118
00119 if (targetBlock == NULL) {
00120
00121
00122 if (heap.usedBlocks == heap.numBlocks) {
00123 static const size_t maxNumBlocks = ULONG_MAX / sizeof(CollectorBlock*) / GROWTH_FACTOR;
00124 if (heap.numBlocks > maxNumBlocks)
00125 return 0L;
00126 heap.numBlocks = MAX(MIN_ARRAY_SIZE, heap.numBlocks * GROWTH_FACTOR);
00127 heap.blocks = (CollectorBlock **)realloc(heap.blocks, heap.numBlocks * sizeof(CollectorBlock *));
00128 }
00129
00130 targetBlock = (CollectorBlock *)calloc(1, sizeof(CollectorBlock));
00131 targetBlock->freeList = targetBlock->cells;
00132 heap.blocks[heap.usedBlocks] = targetBlock;
00133 heap.usedBlocks++;
00134 }
00135
00136
00137 CollectorCell *newCell = targetBlock->freeList;
00138
00139 ValueImp *imp = (ValueImp*)newCell;
00140 if (imp->_vd != NULL) {
00141 targetBlock->freeList = (CollectorCell*)(imp->_vd);
00142 } else if (targetBlock->usedCells == (CELLS_PER_BLOCK - 1)) {
00143
00144 targetBlock->freeList = NULL;
00145 } else {
00146
00147 targetBlock->freeList = newCell + 1;
00148 }
00149
00150 targetBlock->usedCells++;
00151 heap.numLiveObjects++;
00152
00153 ((ValueImp *)(newCell))->_flags = 0;
00154 return (void *)(newCell);
00155 }
00156
00157 bool Collector::collect()
00158 {
00159 bool deleted = false;
00160
00161
00162
00163 if (InterpreterImp::s_hook) {
00164 InterpreterImp *scr = InterpreterImp::s_hook;
00165 do {
00166
00167 scr->mark();
00168 scr = scr->next;
00169 } while (scr != InterpreterImp::s_hook);
00170 }
00171
00172
00173 for (int block = 0; block < heap.usedBlocks; block++) {
00174
00175 int minimumCellsToProcess = heap.blocks[block]->usedCells;
00176 CollectorBlock *curBlock = heap.blocks[block];
00177
00178 for (int cell = 0; cell < CELLS_PER_BLOCK; cell++) {
00179 if (minimumCellsToProcess < cell) {
00180 goto skip_block_mark;
00181 }
00182
00183 ValueImp *imp = (ValueImp *)(curBlock->cells + cell);
00184
00185 if (!(imp->_flags & ValueImp::VI_DESTRUCTED)) {
00186
00187 if ((imp->_flags & (ValueImp::VI_CREATED|ValueImp::VI_MARKED)) == ValueImp::VI_CREATED &&
00188 ((imp->_flags & ValueImp::VI_GCALLOWED) == 0 || imp->refcount != 0)) {
00189 imp->mark();
00190 }
00191 } else {
00192 minimumCellsToProcess++;
00193 }
00194 }
00195 skip_block_mark: ;
00196 }
00197
00198 for (int cell = 0; cell < heap.usedOversizeCells; cell++) {
00199 ValueImp *imp = (ValueImp *)heap.oversizeCells[cell];
00200 if ((imp->_flags & (ValueImp::VI_CREATED|ValueImp::VI_MARKED)) == ValueImp::VI_CREATED &&
00201 ((imp->_flags & ValueImp::VI_GCALLOWED) == 0 || imp->refcount != 0)) {
00202 imp->mark();
00203 }
00204 }
00205
00206
00207
00208 int emptyBlocks = 0;
00209
00210 for (int block = 0; block < heap.usedBlocks; block++) {
00211 CollectorBlock *curBlock = heap.blocks[block];
00212
00213 int minimumCellsToProcess = curBlock->usedCells;
00214
00215 for (int cell = 0; cell < CELLS_PER_BLOCK; cell++) {
00216 if (minimumCellsToProcess < cell) {
00217 goto skip_block_sweep;
00218 }
00219
00220 ValueImp *imp = (ValueImp *)(curBlock->cells + cell);
00221
00222 if (!(imp->_flags & ValueImp::VI_DESTRUCTED)) {
00223 if (!imp->refcount && imp->_flags == (ValueImp::VI_GCALLOWED | ValueImp::VI_CREATED)) {
00224
00225
00226 imp->~ValueImp();
00227 curBlock->usedCells--;
00228 heap.numLiveObjects--;
00229 deleted = true;
00230
00231
00232 imp->_vd = (ValueImpPrivate*)curBlock->freeList;
00233 curBlock->freeList = (CollectorCell *)imp;
00234
00235 } else {
00236 imp->_flags &= ~ValueImp::VI_MARKED;
00237 }
00238 } else {
00239 minimumCellsToProcess++;
00240 }
00241 }
00242
00243 skip_block_sweep:
00244
00245 if (heap.blocks[block]->usedCells == 0) {
00246 emptyBlocks++;
00247 if (emptyBlocks > SPARE_EMPTY_BLOCKS) {
00248 #ifndef DEBUG_COLLECTOR
00249 free(heap.blocks[block]);
00250 #endif
00251
00252 heap.blocks[block] = heap.blocks[heap.usedBlocks - 1];
00253 heap.usedBlocks--;
00254 block--;
00255
00256 if (heap.numBlocks > MIN_ARRAY_SIZE && heap.usedBlocks < heap.numBlocks / LOW_WATER_FACTOR) {
00257 heap.numBlocks = heap.numBlocks / GROWTH_FACTOR;
00258 heap.blocks = (CollectorBlock **)realloc(heap.blocks, heap.numBlocks * sizeof(CollectorBlock *));
00259 }
00260 }
00261 }
00262 }
00263
00264 if (deleted) {
00265 heap.firstBlockWithPossibleSpace = 0;
00266 }
00267
00268 int cell = 0;
00269 while (cell < heap.usedOversizeCells) {
00270 ValueImp *imp = (ValueImp *)heap.oversizeCells[cell];
00271
00272 if (!imp->refcount &&
00273 imp->_flags == (ValueImp::VI_GCALLOWED | ValueImp::VI_CREATED)) {
00274
00275 imp->~ValueImp();
00276 #ifndef DEBUG_COLLECTOR
00277 free((void *)imp);
00278 #endif
00279
00280
00281 heap.oversizeCells[cell] = heap.oversizeCells[heap.usedOversizeCells - 1];
00282
00283 heap.usedOversizeCells--;
00284 deleted = true;
00285 heap.numLiveObjects--;
00286
00287 if (heap.numOversizeCells > MIN_ARRAY_SIZE && heap.usedOversizeCells < heap.numOversizeCells / LOW_WATER_FACTOR) {
00288 heap.numOversizeCells = heap.numOversizeCells / GROWTH_FACTOR;
00289 heap.oversizeCells = (CollectorCell **)realloc(heap.oversizeCells, heap.numOversizeCells * sizeof(CollectorCell *));
00290 }
00291
00292 } else {
00293 imp->_flags &= ~ValueImp::VI_MARKED;
00294 cell++;
00295 }
00296 }
00297
00298 heap.numAllocationsSinceLastCollect = 0;
00299
00300 memoryFull = (heap.numLiveObjects >= KJS_MEM_LIMIT);
00301
00302 return deleted;
00303 }
00304
00305 int Collector::size()
00306 {
00307 return heap.numLiveObjects;
00308 }
00309
00310 #ifdef KJS_DEBUG_MEM
00311 void Collector::finalCheck()
00312 {
00313 }
00314 #endif
00315
00316 }
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