![[BACK]](/cvsweb/icons/back.gif){kind=icon}
Return to jsdhash.h CVS log ![[TXT]](/cvsweb/icons/text.gif){kind=icon}
![[DIR]](/cvsweb/icons/dir.gif){kind=icon}
Up to [Synchronet] / sbbs / include / mozilla / js|
Return to jsdhash.h CVS log | Up to [Synchronet] / sbbs / include / mozilla / js |
1.1 ! root 1: /* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ ! 2: /* ***** BEGIN LICENSE BLOCK ***** ! 3: * Version: MPL 1.1/GPL 2.0/LGPL 2.1 ! 4: * ! 5: * The contents of this file are subject to the Mozilla Public License Version ! 6: * 1.1 (the "License"); you may not use this file except in compliance with ! 7: * the License. You may obtain a copy of the License at ! 8: * http://www.mozilla.org/MPL/ ! 9: * ! 10: * Software distributed under the License is distributed on an "AS IS" basis, ! 11: * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License ! 12: * for the specific language governing rights and limitations under the ! 13: * License. ! 14: * ! 15: * The Original Code is Mozilla JavaScript code. ! 16: * ! 17: * The Initial Developer of the Original Code is ! 18: * Netscape Communications Corporation. ! 19: * Portions created by the Initial Developer are Copyright (C) 1999-2001 ! 20: * the Initial Developer. All Rights Reserved. ! 21: * ! 22: * Contributor(s): ! 23: * Brendan Eich <[email protected]> (Original Author) ! 24: * ! 25: * Alternatively, the contents of this file may be used under the terms of ! 26: * either of the GNU General Public License Version 2 or later (the "GPL"), ! 27: * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), ! 28: * in which case the provisions of the GPL or the LGPL are applicable instead ! 29: * of those above. If you wish to allow use of your version of this file only ! 30: * under the terms of either the GPL or the LGPL, and not to allow others to ! 31: * use your version of this file under the terms of the MPL, indicate your ! 32: * decision by deleting the provisions above and replace them with the notice ! 33: * and other provisions required by the GPL or the LGPL. If you do not delete ! 34: * the provisions above, a recipient may use your version of this file under ! 35: * the terms of any one of the MPL, the GPL or the LGPL. ! 36: * ! 37: * ***** END LICENSE BLOCK ***** */ ! 38: ! 39: #ifndef jsdhash_h___ ! 40: #define jsdhash_h___ ! 41: /* ! 42: * Double hashing, a la Knuth 6. ! 43: */ ! 44: #include "jstypes.h" ! 45: ! 46: JS_BEGIN_EXTERN_C ! 47: ! 48: #if defined(__GNUC__) && defined(__i386__) && (__GNUC__ >= 3) && !defined(XP_OS2) ! 49: #define JS_DHASH_FASTCALL __attribute__ ((regparm (3),stdcall)) ! 50: #else ! 51: #define JS_DHASH_FASTCALL ! 52: #endif ! 53: ! 54: #ifdef DEBUG_XXXbrendan ! 55: #define JS_DHASHMETER 1 ! 56: #endif ! 57: ! 58: /* Table size limit, do not equal or exceed (see min&maxAlphaFrac, below). */ ! 59: #undef JS_DHASH_SIZE_LIMIT ! 60: #define JS_DHASH_SIZE_LIMIT JS_BIT(24) ! 61: ! 62: /* Minimum table size, or gross entry count (net is at most .75 loaded). */ ! 63: #ifndef JS_DHASH_MIN_SIZE ! 64: #define JS_DHASH_MIN_SIZE 16 ! 65: #elif (JS_DHASH_MIN_SIZE & (JS_DHASH_MIN_SIZE - 1)) != 0 ! 66: #error "JS_DHASH_MIN_SIZE must be a power of two!" ! 67: #endif ! 68: ! 69: /* ! 70: * Multiplicative hash uses an unsigned 32 bit integer and the golden ratio, ! 71: * expressed as a fixed-point 32-bit fraction. ! 72: */ ! 73: #define JS_DHASH_BITS 32 ! 74: #define JS_DHASH_GOLDEN_RATIO 0x9E3779B9U ! 75: ! 76: /* Primitive and forward-struct typedefs. */ ! 77: typedef uint32 JSDHashNumber; ! 78: typedef struct JSDHashEntryHdr JSDHashEntryHdr; ! 79: typedef struct JSDHashEntryStub JSDHashEntryStub; ! 80: typedef struct JSDHashTable JSDHashTable; ! 81: typedef struct JSDHashTableOps JSDHashTableOps; ! 82: ! 83: /* ! 84: * Table entry header structure. ! 85: * ! 86: * In order to allow in-line allocation of key and value, we do not declare ! 87: * either here. Instead, the API uses const void *key as a formal parameter, ! 88: * and asks each entry for its key when necessary via a getKey callback, used ! 89: * when growing or shrinking the table. Other callback types are defined ! 90: * below and grouped into the JSDHashTableOps structure, for single static ! 91: * initialization per hash table sub-type. ! 92: * ! 93: * Each hash table sub-type should nest the JSDHashEntryHdr structure at the ! 94: * front of its particular entry type. The keyHash member contains the result ! 95: * of multiplying the hash code returned from the hashKey callback (see below) ! 96: * by JS_DHASH_GOLDEN_RATIO, then constraining the result to avoid the magic 0 ! 97: * and 1 values. The stored keyHash value is table size invariant, and it is ! 98: * maintained automatically by JS_DHashTableOperate -- users should never set ! 99: * it, and its only uses should be via the entry macros below. ! 100: * ! 101: * The JS_DHASH_ENTRY_IS_LIVE macro tests whether entry is neither free nor ! 102: * removed. An entry may be either busy or free; if busy, it may be live or ! 103: * removed. Consumers of this API should not access members of entries that ! 104: * are not live. ! 105: * ! 106: * However, use JS_DHASH_ENTRY_IS_BUSY for faster liveness testing of entries ! 107: * returned by JS_DHashTableOperate, as JS_DHashTableOperate never returns a ! 108: * non-live, busy (i.e., removed) entry pointer to its caller. See below for ! 109: * more details on JS_DHashTableOperate's calling rules. ! 110: */ ! 111: struct JSDHashEntryHdr { ! 112: JSDHashNumber keyHash; /* every entry must begin like this */ ! 113: }; ! 114: ! 115: #define JS_DHASH_ENTRY_IS_FREE(entry) ((entry)->keyHash == 0) ! 116: #define JS_DHASH_ENTRY_IS_BUSY(entry) (!JS_DHASH_ENTRY_IS_FREE(entry)) ! 117: #define JS_DHASH_ENTRY_IS_LIVE(entry) ((entry)->keyHash >= 2) ! 118: ! 119: /* ! 120: * A JSDHashTable is currently 8 words (without the JS_DHASHMETER overhead) ! 121: * on most architectures, and may be allocated on the stack or within another ! 122: * structure or class (see below for the Init and Finish functions to use). ! 123: * ! 124: * To decide whether to use double hashing vs. chaining, we need to develop a ! 125: * trade-off relation, as follows: ! 126: * ! 127: * Let alpha be the load factor, esize the entry size in words, count the ! 128: * entry count, and pow2 the power-of-two table size in entries. ! 129: * ! 130: * (JSDHashTable overhead) > (JSHashTable overhead) ! 131: * (unused table entry space) > (malloc and .next overhead per entry) + ! 132: * (buckets overhead) ! 133: * (1 - alpha) * esize * pow2 > 2 * count + pow2 ! 134: * ! 135: * Notice that alpha is by definition (count / pow2): ! 136: * ! 137: * (1 - alpha) * esize * pow2 > 2 * alpha * pow2 + pow2 ! 138: * (1 - alpha) * esize > 2 * alpha + 1 ! 139: * ! 140: * esize > (1 + 2 * alpha) / (1 - alpha) ! 141: * ! 142: * This assumes both tables must keep keyHash, key, and value for each entry, ! 143: * where key and value point to separately allocated strings or structures. ! 144: * If key and value can be combined into one pointer, then the trade-off is: ! 145: * ! 146: * esize > (1 + 3 * alpha) / (1 - alpha) ! 147: * ! 148: * If the entry value can be a subtype of JSDHashEntryHdr, rather than a type ! 149: * that must be allocated separately and referenced by an entry.value pointer ! 150: * member, and provided key's allocation can be fused with its entry's, then ! 151: * k (the words wasted per entry with chaining) is 4. ! 152: * ! 153: * To see these curves, feed gnuplot input like so: ! 154: * ! 155: * gnuplot> f(x,k) = (1 + k * x) / (1 - x) ! 156: * gnuplot> plot [0:.75] f(x,2), f(x,3), f(x,4) ! 157: * ! 158: * For k of 2 and a well-loaded table (alpha > .5), esize must be more than 4 ! 159: * words for chaining to be more space-efficient than double hashing. ! 160: * ! 161: * Solving for alpha helps us decide when to shrink an underloaded table: ! 162: * ! 163: * esize > (1 + k * alpha) / (1 - alpha) ! 164: * esize - alpha * esize > 1 + k * alpha ! 165: * esize - 1 > (k + esize) * alpha ! 166: * (esize - 1) / (k + esize) > alpha ! 167: * ! 168: * alpha < (esize - 1) / (esize + k) ! 169: * ! 170: * Therefore double hashing should keep alpha >= (esize - 1) / (esize + k), ! 171: * assuming esize is not too large (in which case, chaining should probably be ! 172: * used for any alpha). For esize=2 and k=3, we want alpha >= .2; for esize=3 ! 173: * and k=2, we want alpha >= .4. For k=4, esize could be 6, and alpha >= .5 ! 174: * would still obtain. See the JS_DHASH_MIN_ALPHA macro further below. ! 175: * ! 176: * The current implementation uses a configurable lower bound on alpha, which ! 177: * defaults to .25, when deciding to shrink the table (while still respecting ! 178: * JS_DHASH_MIN_SIZE). ! 179: * ! 180: * Note a qualitative difference between chaining and double hashing: under ! 181: * chaining, entry addresses are stable across table shrinks and grows. With ! 182: * double hashing, you can't safely hold an entry pointer and use it after an ! 183: * ADD or REMOVE operation, unless you sample table->generation before adding ! 184: * or removing, and compare the sample after, dereferencing the entry pointer ! 185: * only if table->generation has not changed. ! 186: * ! 187: * The moral of this story: there is no one-size-fits-all hash table scheme, ! 188: * but for small table entry size, and assuming entry address stability is not ! 189: * required, double hashing wins. ! 190: */ ! 191: struct JSDHashTable { ! 192: const JSDHashTableOps *ops; /* virtual operations, see below */ ! 193: void *data; /* ops- and instance-specific data */ ! 194: int16 hashShift; /* multiplicative hash shift */ ! 195: uint8 maxAlphaFrac; /* 8-bit fixed point max alpha */ ! 196: uint8 minAlphaFrac; /* 8-bit fixed point min alpha */ ! 197: uint32 entrySize; /* number of bytes in an entry */ ! 198: uint32 entryCount; /* number of entries in table */ ! 199: uint32 removedCount; /* removed entry sentinels in table */ ! 200: uint32 generation; /* entry storage generation number */ ! 201: char *entryStore; /* entry storage */ ! 202: #ifdef JS_DHASHMETER ! 203: struct JSDHashStats { ! 204: uint32 searches; /* total number of table searches */ ! 205: uint32 steps; /* hash chain links traversed */ ! 206: uint32 hits; /* searches that found key */ ! 207: uint32 misses; /* searches that didn't find key */ ! 208: uint32 lookups; /* number of JS_DHASH_LOOKUPs */ ! 209: uint32 addMisses; /* adds that miss, and do work */ ! 210: uint32 addOverRemoved; /* adds that recycled a removed entry */ ! 211: uint32 addHits; /* adds that hit an existing entry */ ! 212: uint32 addFailures; /* out-of-memory during add growth */ ! 213: uint32 removeHits; /* removes that hit, and do work */ ! 214: uint32 removeMisses; /* useless removes that miss */ ! 215: uint32 removeFrees; /* removes that freed entry directly */ ! 216: uint32 removeEnums; /* removes done by Enumerate */ ! 217: uint32 grows; /* table expansions */ ! 218: uint32 shrinks; /* table contractions */ ! 219: uint32 compresses; /* table compressions */ ! 220: uint32 enumShrinks; /* contractions after Enumerate */ ! 221: } stats; ! 222: #endif ! 223: }; ! 224: ! 225: /* ! 226: * Size in entries (gross, not net of free and removed sentinels) for table. ! 227: * We store hashShift rather than sizeLog2 to optimize the collision-free case ! 228: * in SearchTable. ! 229: */ ! 230: #define JS_DHASH_TABLE_SIZE(table) JS_BIT(JS_DHASH_BITS - (table)->hashShift) ! 231: ! 232: /* ! 233: * Table space at entryStore is allocated and freed using these callbacks. ! 234: * The allocator should return null on error only (not if called with nbytes ! 235: * equal to 0; but note that jsdhash.c code will never call with 0 nbytes). ! 236: */ ! 237: typedef void * ! 238: (* JS_DLL_CALLBACK JSDHashAllocTable)(JSDHashTable *table, uint32 nbytes); ! 239: ! 240: typedef void ! 241: (* JS_DLL_CALLBACK JSDHashFreeTable) (JSDHashTable *table, void *ptr); ! 242: ! 243: /* ! 244: * When a table grows or shrinks, each entry is queried for its key using this ! 245: * callback. NB: in that event, entry is not in table any longer; it's in the ! 246: * old entryStore vector, which is due to be freed once all entries have been ! 247: * moved via moveEntry callbacks. ! 248: */ ! 249: typedef const void * ! 250: (* JS_DLL_CALLBACK JSDHashGetKey) (JSDHashTable *table, ! 251: JSDHashEntryHdr *entry); ! 252: ! 253: /* ! 254: * Compute the hash code for a given key to be looked up, added, or removed ! 255: * from table. A hash code may have any JSDHashNumber value. ! 256: */ ! 257: typedef JSDHashNumber ! 258: (* JS_DLL_CALLBACK JSDHashHashKey) (JSDHashTable *table, const void *key); ! 259: ! 260: /* ! 261: * Compare the key identifying entry in table with the provided key parameter. ! 262: * Return JS_TRUE if keys match, JS_FALSE otherwise. ! 263: */ ! 264: typedef JSBool ! 265: (* JS_DLL_CALLBACK JSDHashMatchEntry)(JSDHashTable *table, ! 266: const JSDHashEntryHdr *entry, ! 267: const void *key); ! 268: ! 269: /* ! 270: * Copy the data starting at from to the new entry storage at to. Do not add ! 271: * reference counts for any strong references in the entry, however, as this ! 272: * is a "move" operation: the old entry storage at from will be freed without ! 273: * any reference-decrementing callback shortly. ! 274: */ ! 275: typedef void ! 276: (* JS_DLL_CALLBACK JSDHashMoveEntry)(JSDHashTable *table, ! 277: const JSDHashEntryHdr *from, ! 278: JSDHashEntryHdr *to); ! 279: ! 280: /* ! 281: * Clear the entry and drop any strong references it holds. This callback is ! 282: * invoked during a JS_DHASH_REMOVE operation (see below for operation codes), ! 283: * but only if the given key is found in the table. ! 284: */ ! 285: typedef void ! 286: (* JS_DLL_CALLBACK JSDHashClearEntry)(JSDHashTable *table, ! 287: JSDHashEntryHdr *entry); ! 288: ! 289: /* ! 290: * Called when a table (whether allocated dynamically by itself, or nested in ! 291: * a larger structure, or allocated on the stack) is finished. This callback ! 292: * allows table->ops-specific code to finalize table->data. ! 293: */ ! 294: typedef void ! 295: (* JS_DLL_CALLBACK JSDHashFinalize) (JSDHashTable *table); ! 296: ! 297: /* ! 298: * Initialize a new entry, apart from keyHash. This function is called when ! 299: * JS_DHashTableOperate's JS_DHASH_ADD case finds no existing entry for the ! 300: * given key, and must add a new one. At that point, entry->keyHash is not ! 301: * set yet, to avoid claiming the last free entry in a severely overloaded ! 302: * table. ! 303: */ ! 304: typedef JSBool ! 305: (* JS_DLL_CALLBACK JSDHashInitEntry)(JSDHashTable *table, ! 306: JSDHashEntryHdr *entry, ! 307: const void *key); ! 308: ! 309: /* ! 310: * Finally, the "vtable" structure for JSDHashTable. The first eight hooks ! 311: * must be provided by implementations; they're called unconditionally by the ! 312: * generic jsdhash.c code. Hooks after these may be null. ! 313: * ! 314: * Summary of allocation-related hook usage with C++ placement new emphasis: ! 315: * allocTable Allocate raw bytes with malloc, no ctors run. ! 316: * freeTable Free raw bytes with free, no dtors run. ! 317: * initEntry Call placement new using default key-based ctor. ! 318: * Return JS_TRUE on success, JS_FALSE on error. ! 319: * moveEntry Call placement new using copy ctor, run dtor on old ! 320: * entry storage. ! 321: * clearEntry Run dtor on entry. ! 322: * finalize Stub unless table->data was initialized and needs to ! 323: * be finalized. ! 324: * ! 325: * Note the reason why initEntry is optional: the default hooks (stubs) clear ! 326: * entry storage: On successful JS_DHashTableOperate(tbl, key, JS_DHASH_ADD), ! 327: * the returned entry pointer addresses an entry struct whose keyHash member ! 328: * has been set non-zero, but all other entry members are still clear (null). ! 329: * JS_DHASH_ADD callers can test such members to see whether the entry was ! 330: * newly created by the JS_DHASH_ADD call that just succeeded. If placement ! 331: * new or similar initialization is required, define an initEntry hook. Of ! 332: * course, the clearEntry hook must zero or null appropriately. ! 333: * ! 334: * XXX assumes 0 is null for pointer types. ! 335: */ ! 336: struct JSDHashTableOps { ! 337: /* Mandatory hooks. All implementations must provide these. */ ! 338: JSDHashAllocTable allocTable; ! 339: JSDHashFreeTable freeTable; ! 340: JSDHashGetKey getKey; ! 341: JSDHashHashKey hashKey; ! 342: JSDHashMatchEntry matchEntry; ! 343: JSDHashMoveEntry moveEntry; ! 344: JSDHashClearEntry clearEntry; ! 345: JSDHashFinalize finalize; ! 346: ! 347: /* Optional hooks start here. If null, these are not called. */ ! 348: JSDHashInitEntry initEntry; ! 349: }; ! 350: ! 351: /* ! 352: * Default implementations for the above ops. ! 353: */ ! 354: extern JS_PUBLIC_API(void *) ! 355: JS_DHashAllocTable(JSDHashTable *table, uint32 nbytes); ! 356: ! 357: extern JS_PUBLIC_API(void) ! 358: JS_DHashFreeTable(JSDHashTable *table, void *ptr); ! 359: ! 360: extern JS_PUBLIC_API(JSDHashNumber) ! 361: JS_DHashStringKey(JSDHashTable *table, const void *key); ! 362: ! 363: /* A minimal entry contains a keyHash header and a void key pointer. */ ! 364: struct JSDHashEntryStub { ! 365: JSDHashEntryHdr hdr; ! 366: const void *key; ! 367: }; ! 368: ! 369: extern JS_PUBLIC_API(const void *) ! 370: JS_DHashGetKeyStub(JSDHashTable *table, JSDHashEntryHdr *entry); ! 371: ! 372: extern JS_PUBLIC_API(JSDHashNumber) ! 373: JS_DHashVoidPtrKeyStub(JSDHashTable *table, const void *key); ! 374: ! 375: extern JS_PUBLIC_API(JSBool) ! 376: JS_DHashMatchEntryStub(JSDHashTable *table, ! 377: const JSDHashEntryHdr *entry, ! 378: const void *key); ! 379: ! 380: extern JS_PUBLIC_API(JSBool) ! 381: JS_DHashMatchStringKey(JSDHashTable *table, ! 382: const JSDHashEntryHdr *entry, ! 383: const void *key); ! 384: ! 385: extern JS_PUBLIC_API(void) ! 386: JS_DHashMoveEntryStub(JSDHashTable *table, ! 387: const JSDHashEntryHdr *from, ! 388: JSDHashEntryHdr *to); ! 389: ! 390: extern JS_PUBLIC_API(void) ! 391: JS_DHashClearEntryStub(JSDHashTable *table, JSDHashEntryHdr *entry); ! 392: ! 393: extern JS_PUBLIC_API(void) ! 394: JS_DHashFreeStringKey(JSDHashTable *table, JSDHashEntryHdr *entry); ! 395: ! 396: extern JS_PUBLIC_API(void) ! 397: JS_DHashFinalizeStub(JSDHashTable *table); ! 398: ! 399: /* ! 400: * If you use JSDHashEntryStub or a subclass of it as your entry struct, and ! 401: * if your entries move via memcpy and clear via memset(0), you can use these ! 402: * stub operations. ! 403: */ ! 404: extern JS_PUBLIC_API(const JSDHashTableOps *) ! 405: JS_DHashGetStubOps(void); ! 406: ! 407: /* ! 408: * Dynamically allocate a new JSDHashTable using malloc, initialize it using ! 409: * JS_DHashTableInit, and return its address. Return null on malloc failure. ! 410: * Note that the entry storage at table->entryStore will be allocated using ! 411: * the ops->allocTable callback. ! 412: */ ! 413: extern JS_PUBLIC_API(JSDHashTable *) ! 414: JS_NewDHashTable(const JSDHashTableOps *ops, void *data, uint32 entrySize, ! 415: uint32 capacity); ! 416: ! 417: /* ! 418: * Finalize table's data, free its entry storage (via table->ops->freeTable), ! 419: * and return the memory starting at table to the malloc heap. ! 420: */ ! 421: extern JS_PUBLIC_API(void) ! 422: JS_DHashTableDestroy(JSDHashTable *table); ! 423: ! 424: /* ! 425: * Initialize table with ops, data, entrySize, and capacity. Capacity is a ! 426: * guess for the smallest table size at which the table will usually be less ! 427: * than 75% loaded (the table will grow or shrink as needed; capacity serves ! 428: * only to avoid inevitable early growth from JS_DHASH_MIN_SIZE). ! 429: */ ! 430: extern JS_PUBLIC_API(JSBool) ! 431: JS_DHashTableInit(JSDHashTable *table, const JSDHashTableOps *ops, void *data, ! 432: uint32 entrySize, uint32 capacity); ! 433: ! 434: /* ! 435: * Set maximum and minimum alpha for table. The defaults are 0.75 and .25. ! 436: * maxAlpha must be in [0.5, 0.9375] for the default JS_DHASH_MIN_SIZE; or if ! 437: * MinSize=JS_DHASH_MIN_SIZE <= 256, in [0.5, (float)(MinSize-1)/MinSize]; or ! 438: * else in [0.5, 255.0/256]. minAlpha must be in [0, maxAlpha / 2), so that ! 439: * we don't shrink on the very next remove after growing a table upon adding ! 440: * an entry that brings entryCount past maxAlpha * tableSize. ! 441: */ ! 442: JS_PUBLIC_API(void) ! 443: JS_DHashTableSetAlphaBounds(JSDHashTable *table, ! 444: float maxAlpha, ! 445: float minAlpha); ! 446: ! 447: /* ! 448: * Call this macro with k, the number of pointer-sized words wasted per entry ! 449: * under chaining, to compute the minimum alpha at which double hashing still ! 450: * beats chaining. ! 451: */ ! 452: #define JS_DHASH_MIN_ALPHA(table, k) \ ! 453: ((float)((table)->entrySize / sizeof(void *) - 1) \ ! 454: / ((table)->entrySize / sizeof(void *) + (k))) ! 455: ! 456: /* ! 457: * Finalize table's data, free its entry storage using table->ops->freeTable, ! 458: * and leave its members unchanged from their last live values (which leaves ! 459: * pointers dangling). If you want to burn cycles clearing table, it's up to ! 460: * your code to call memset. ! 461: */ ! 462: extern JS_PUBLIC_API(void) ! 463: JS_DHashTableFinish(JSDHashTable *table); ! 464: ! 465: /* ! 466: * To consolidate keyHash computation and table grow/shrink code, we use a ! 467: * single entry point for lookup, add, and remove operations. The operation ! 468: * codes are declared here, along with codes returned by JSDHashEnumerator ! 469: * functions, which control JS_DHashTableEnumerate's behavior. ! 470: */ ! 471: typedef enum JSDHashOperator { ! 472: JS_DHASH_LOOKUP = 0, /* lookup entry */ ! 473: JS_DHASH_ADD = 1, /* add entry */ ! 474: JS_DHASH_REMOVE = 2, /* remove entry, or enumerator says remove */ ! 475: JS_DHASH_NEXT = 0, /* enumerator says continue */ ! 476: JS_DHASH_STOP = 1 /* enumerator says stop */ ! 477: } JSDHashOperator; ! 478: ! 479: /* ! 480: * To lookup a key in table, call: ! 481: * ! 482: * entry = JS_DHashTableOperate(table, key, JS_DHASH_LOOKUP); ! 483: * ! 484: * If JS_DHASH_ENTRY_IS_BUSY(entry) is true, key was found and it identifies ! 485: * entry. If JS_DHASH_ENTRY_IS_FREE(entry) is true, key was not found. ! 486: * ! 487: * To add an entry identified by key to table, call: ! 488: * ! 489: * entry = JS_DHashTableOperate(table, key, JS_DHASH_ADD); ! 490: * ! 491: * If entry is null upon return, then either the table is severely overloaded, ! 492: * and memory can't be allocated for entry storage via table->ops->allocTable; ! 493: * Or if table->ops->initEntry is non-null, the table->ops->initEntry op may ! 494: * have returned false. ! 495: * ! 496: * Otherwise, entry->keyHash has been set so that JS_DHASH_ENTRY_IS_BUSY(entry) ! 497: * is true, and it is up to the caller to initialize the key and value parts ! 498: * of the entry sub-type, if they have not been set already (i.e. if entry was ! 499: * not already in the table, and if the optional initEntry hook was not used). ! 500: * ! 501: * To remove an entry identified by key from table, call: ! 502: * ! 503: * (void) JS_DHashTableOperate(table, key, JS_DHASH_REMOVE); ! 504: * ! 505: * If key's entry is found, it is cleared (via table->ops->clearEntry) and ! 506: * the entry is marked so that JS_DHASH_ENTRY_IS_FREE(entry). This operation ! 507: * returns null unconditionally; you should ignore its return value. ! 508: */ ! 509: extern JS_PUBLIC_API(JSDHashEntryHdr *) JS_DHASH_FASTCALL ! 510: JS_DHashTableOperate(JSDHashTable *table, const void *key, JSDHashOperator op); ! 511: ! 512: /* ! 513: * Remove an entry already accessed via LOOKUP or ADD. ! 514: * ! 515: * NB: this is a "raw" or low-level routine, intended to be used only where ! 516: * the inefficiency of a full JS_DHashTableOperate (which rehashes in order ! 517: * to find the entry given its key) is not tolerable. This function does not ! 518: * shrink the table if it is underloaded. It does not update stats #ifdef ! 519: * JS_DHASHMETER, either. ! 520: */ ! 521: extern JS_PUBLIC_API(void) ! 522: JS_DHashTableRawRemove(JSDHashTable *table, JSDHashEntryHdr *entry); ! 523: ! 524: /* ! 525: * Enumerate entries in table using etor: ! 526: * ! 527: * count = JS_DHashTableEnumerate(table, etor, arg); ! 528: * ! 529: * JS_DHashTableEnumerate calls etor like so: ! 530: * ! 531: * op = etor(table, entry, number, arg); ! 532: * ! 533: * where number is a zero-based ordinal assigned to live entries according to ! 534: * their order in table->entryStore. ! 535: * ! 536: * The return value, op, is treated as a set of flags. If op is JS_DHASH_NEXT, ! 537: * then continue enumerating. If op contains JS_DHASH_REMOVE, then clear (via ! 538: * table->ops->clearEntry) and free entry. Then we check whether op contains ! 539: * JS_DHASH_STOP; if so, stop enumerating and return the number of live entries ! 540: * that were enumerated so far. Return the total number of live entries when ! 541: * enumeration completes normally. ! 542: * ! 543: * If etor calls JS_DHashTableOperate on table with op != JS_DHASH_LOOKUP, it ! 544: * must return JS_DHASH_STOP; otherwise undefined behavior results. ! 545: * ! 546: * If any enumerator returns JS_DHASH_REMOVE, table->entryStore may be shrunk ! 547: * or compressed after enumeration, but before JS_DHashTableEnumerate returns. ! 548: * Such an enumerator therefore can't safely set aside entry pointers, but an ! 549: * enumerator that never returns JS_DHASH_REMOVE can set pointers to entries ! 550: * aside, e.g., to avoid copying live entries into an array of the entry type. ! 551: * Copying entry pointers is cheaper, and safe so long as the caller of such a ! 552: * "stable" Enumerate doesn't use the set-aside pointers after any call either ! 553: * to PL_DHashTableOperate, or to an "unstable" form of Enumerate, which might ! 554: * grow or shrink entryStore. ! 555: * ! 556: * If your enumerator wants to remove certain entries, but set aside pointers ! 557: * to other entries that it retains, it can use JS_DHashTableRawRemove on the ! 558: * entries to be removed, returning JS_DHASH_NEXT to skip them. Likewise, if ! 559: * you want to remove entries, but for some reason you do not want entryStore ! 560: * to be shrunk or compressed, you can call JS_DHashTableRawRemove safely on ! 561: * the entry being enumerated, rather than returning JS_DHASH_REMOVE. ! 562: */ ! 563: typedef JSDHashOperator ! 564: (* JS_DLL_CALLBACK JSDHashEnumerator)(JSDHashTable *table, JSDHashEntryHdr *hdr, ! 565: uint32 number, void *arg); ! 566: ! 567: extern JS_PUBLIC_API(uint32) ! 568: JS_DHashTableEnumerate(JSDHashTable *table, JSDHashEnumerator etor, void *arg); ! 569: ! 570: #ifdef JS_DHASHMETER ! 571: #include <stdio.h> ! 572: ! 573: extern JS_PUBLIC_API(void) ! 574: JS_DHashTableDumpMeter(JSDHashTable *table, JSDHashEnumerator dump, FILE *fp); ! 575: #endif ! 576: ! 577: JS_END_EXTERN_C ! 578: ! 579: #endif /* jsdhash_h___ */
This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.