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jsscope.c
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jsscope.c
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/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sw=4 et tw=78:
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla Communicator client code, released
* March 31, 1998.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/*
* JS symbol tables.
*/
#include "jsstddef.h"
#include <stdlib.h>
#include <string.h>
#include "jstypes.h"
#include "jsarena.h"
#include "jsbit.h"
#include "jsclist.h"
#include "jsdhash.h"
#include "jsutil.h" /* Added by JSIFY */
#include "jsapi.h"
#include "jsatom.h"
#include "jscntxt.h"
#include "jsdbgapi.h"
#include "jslock.h"
#include "jsnum.h"
#include "jsscope.h"
#include "jsstr.h"
JSScope *
js_GetMutableScope(JSContext *cx, JSObject *obj)
{
JSScope *scope, *newscope;
scope = OBJ_SCOPE(obj);
JS_ASSERT(JS_IS_SCOPE_LOCKED(cx, scope));
if (scope->object == obj)
return scope;
newscope = js_NewScope(cx, 0, scope->map.ops, LOCKED_OBJ_GET_CLASS(obj),
obj);
if (!newscope)
return NULL;
JS_LOCK_SCOPE(cx, newscope);
obj->map = js_HoldObjectMap(cx, &newscope->map);
scope = (JSScope *) js_DropObjectMap(cx, &scope->map, obj);
JS_TRANSFER_SCOPE_LOCK(cx, scope, newscope);
return newscope;
}
/*
* JSScope uses multiplicative hashing, _a la_ jsdhash.[ch], but specialized
* to minimize footprint. But if a scope has fewer than SCOPE_HASH_THRESHOLD
* entries, we use linear search and avoid allocating scope->table.
*/
#define SCOPE_HASH_THRESHOLD 6
#define MIN_SCOPE_SIZE_LOG2 4
#define MIN_SCOPE_SIZE JS_BIT(MIN_SCOPE_SIZE_LOG2)
#define SCOPE_TABLE_NBYTES(n) ((n) * sizeof(JSScopeProperty *))
static void
InitMinimalScope(JSScope *scope)
{
scope->hashShift = JS_DHASH_BITS - MIN_SCOPE_SIZE_LOG2;
scope->entryCount = scope->removedCount = 0;
scope->table = NULL;
scope->lastProp = NULL;
}
static JSBool
CreateScopeTable(JSContext *cx, JSScope *scope, JSBool report)
{
int sizeLog2;
JSScopeProperty *sprop, **spp;
JS_ASSERT(!scope->table);
JS_ASSERT(scope->lastProp);
if (scope->entryCount > SCOPE_HASH_THRESHOLD) {
/*
* Ouch: calloc failed at least once already -- let's try again,
* overallocating to hold at least twice the current population.
*/
sizeLog2 = JS_CeilingLog2(2 * scope->entryCount);
scope->hashShift = JS_DHASH_BITS - sizeLog2;
} else {
JS_ASSERT(scope->hashShift == JS_DHASH_BITS - MIN_SCOPE_SIZE_LOG2);
sizeLog2 = MIN_SCOPE_SIZE_LOG2;
}
scope->table = (JSScopeProperty **)
calloc(JS_BIT(sizeLog2), sizeof(JSScopeProperty *));
if (!scope->table) {
if (report)
JS_ReportOutOfMemory(cx);
return JS_FALSE;
}
js_UpdateMallocCounter(cx, JS_BIT(sizeLog2) * sizeof(JSScopeProperty *));
scope->hashShift = JS_DHASH_BITS - sizeLog2;
for (sprop = scope->lastProp; sprop; sprop = sprop->parent) {
spp = js_SearchScope(scope, sprop->id, JS_TRUE);
SPROP_STORE_PRESERVING_COLLISION(spp, sprop);
}
return JS_TRUE;
}
JSScope *
js_NewScope(JSContext *cx, jsrefcount nrefs, JSObjectOps *ops, JSClass *clasp,
JSObject *obj)
{
JSScope *scope;
scope = (JSScope *) JS_malloc(cx, sizeof(JSScope));
if (!scope)
return NULL;
js_InitObjectMap(&scope->map, nrefs, ops, clasp);
scope->object = obj;
scope->flags = 0;
InitMinimalScope(scope);
#ifdef JS_THREADSAFE
scope->ownercx = cx;
memset(&scope->lock, 0, sizeof scope->lock);
/*
* Set u.link = NULL, not u.count = 0, in case the target architecture's
* null pointer has a non-zero integer representation.
*/
scope->u.link = NULL;
#ifdef DEBUG
scope->file[0] = scope->file[1] = scope->file[2] = scope->file[3] = NULL;
scope->line[0] = scope->line[1] = scope->line[2] = scope->line[3] = 0;
#endif
#endif
JS_RUNTIME_METER(cx->runtime, liveScopes);
JS_RUNTIME_METER(cx->runtime, totalScopes);
return scope;
}
#ifdef DEBUG_SCOPE_COUNT
extern void
js_unlog_scope(JSScope *scope);
#endif
void
js_DestroyScope(JSContext *cx, JSScope *scope)
{
#ifdef DEBUG_SCOPE_COUNT
js_unlog_scope(scope);
#endif
#ifdef JS_THREADSAFE
/* Scope must be single-threaded at this point, so set scope->ownercx. */
JS_ASSERT(scope->u.count == 0);
scope->ownercx = cx;
js_FinishLock(&scope->lock);
#endif
if (scope->table)
JS_free(cx, scope->table);
#ifdef DEBUG
JS_LOCK_RUNTIME_VOID(cx->runtime,
cx->runtime->liveScopeProps -= scope->entryCount);
#endif
JS_RUNTIME_UNMETER(cx->runtime, liveScopes);
JS_free(cx, scope);
}
#ifdef DUMP_SCOPE_STATS
typedef struct JSScopeStats {
jsrefcount searches;
jsrefcount steps;
jsrefcount hits;
jsrefcount misses;
jsrefcount stepHits;
jsrefcount stepMisses;
jsrefcount adds;
jsrefcount redundantAdds;
jsrefcount addFailures;
jsrefcount changeFailures;
jsrefcount compresses;
jsrefcount grows;
jsrefcount removes;
jsrefcount removeFrees;
jsrefcount uselessRemoves;
jsrefcount shrinks;
} JSScopeStats;
JS_FRIEND_DATA(JSScopeStats) js_scope_stats;
# define METER(x) JS_ATOMIC_INCREMENT(&js_scope_stats.x)
#else
# define METER(x) /* nothing */
#endif
/*
* Double hashing needs the second hash code to be relatively prime to table
* size, so we simply make hash2 odd. The inputs to multiplicative hash are
* the golden ratio, expressed as a fixed-point 32 bit fraction, and the int
* property index or named property's atom number (observe that most objects
* have either no indexed properties, or almost all indexed and a few names,
* so collisions between index and atom number are unlikely).
*/
#define SCOPE_HASH0(id) (HASH_ID(id) * JS_GOLDEN_RATIO)
#define SCOPE_HASH1(hash0,shift) ((hash0) >> (shift))
#define SCOPE_HASH2(hash0,log2,shift) ((((hash0) << (log2)) >> (shift)) | 1)
JS_FRIEND_API(JSScopeProperty **)
js_SearchScope(JSScope *scope, jsid id, JSBool adding)
{
JSHashNumber hash0, hash1, hash2;
int hashShift, sizeLog2;
JSScopeProperty *stored, *sprop, **spp, **firstRemoved;
uint32 sizeMask;
METER(searches);
if (!scope->table) {
/* Not enough properties to justify hashing: search from lastProp. */
JS_ASSERT(!SCOPE_HAD_MIDDLE_DELETE(scope));
for (spp = &scope->lastProp; (sprop = *spp); spp = &sprop->parent) {
if (sprop->id == id) {
METER(hits);
return spp;
}
}
METER(misses);
return spp;
}
/* Compute the primary hash address. */
hash0 = SCOPE_HASH0(id);
hashShift = scope->hashShift;
hash1 = SCOPE_HASH1(hash0, hashShift);
spp = scope->table + hash1;
/* Miss: return space for a new entry. */
stored = *spp;
if (SPROP_IS_FREE(stored)) {
METER(misses);
return spp;
}
/* Hit: return entry. */
sprop = SPROP_CLEAR_COLLISION(stored);
if (sprop && sprop->id == id) {
METER(hits);
return spp;
}
/* Collision: double hash. */
sizeLog2 = JS_DHASH_BITS - hashShift;
hash2 = SCOPE_HASH2(hash0, sizeLog2, hashShift);
sizeMask = JS_BITMASK(sizeLog2);
/* Save the first removed entry pointer so we can recycle it if adding. */
if (SPROP_IS_REMOVED(stored)) {
firstRemoved = spp;
} else {
firstRemoved = NULL;
if (adding && !SPROP_HAD_COLLISION(stored))
SPROP_FLAG_COLLISION(spp, sprop);
}
for (;;) {
METER(steps);
hash1 -= hash2;
hash1 &= sizeMask;
spp = scope->table + hash1;
stored = *spp;
if (SPROP_IS_FREE(stored)) {
METER(stepMisses);
return (adding && firstRemoved) ? firstRemoved : spp;
}
sprop = SPROP_CLEAR_COLLISION(stored);
if (sprop && sprop->id == id) {
METER(stepHits);
return spp;
}
if (SPROP_IS_REMOVED(stored)) {
if (!firstRemoved)
firstRemoved = spp;
} else {
if (adding && !SPROP_HAD_COLLISION(stored))
SPROP_FLAG_COLLISION(spp, sprop);
}
}
/* NOTREACHED */
return NULL;
}
static JSBool
ChangeScope(JSContext *cx, JSScope *scope, int change)
{
int oldlog2, newlog2;
uint32 oldsize, newsize, nbytes;
JSScopeProperty **table, **oldtable, **spp, **oldspp, *sprop;
/* Grow, shrink, or compress by changing scope->table. */
oldlog2 = JS_DHASH_BITS - scope->hashShift;
newlog2 = oldlog2 + change;
oldsize = JS_BIT(oldlog2);
newsize = JS_BIT(newlog2);
nbytes = SCOPE_TABLE_NBYTES(newsize);
table = (JSScopeProperty **) calloc(nbytes, 1);
if (!table) {
JS_ReportOutOfMemory(cx);
return JS_FALSE;
}
/* Now that we have a new table allocated, update scope members. */
scope->hashShift = JS_DHASH_BITS - newlog2;
scope->removedCount = 0;
oldtable = scope->table;
scope->table = table;
/* Treat the above calloc as a JS_malloc, to match CreateScopeTable. */
cx->runtime->gcMallocBytes += nbytes;
/* Copy only live entries, leaving removed and free ones behind. */
for (oldspp = oldtable; oldsize != 0; oldspp++) {
sprop = SPROP_FETCH(oldspp);
if (sprop) {
spp = js_SearchScope(scope, sprop->id, JS_TRUE);
JS_ASSERT(SPROP_IS_FREE(*spp));
*spp = sprop;
}
oldsize--;
}
/* Finally, free the old table storage. */
JS_free(cx, oldtable);
return JS_TRUE;
}
/*
* Take care to exclude the mark and duplicate bits, in case we're called from
* the GC, or we are searching for a property that has not yet been flagged as
* a duplicate when making a duplicate formal parameter.
*/
#define SPROP_FLAGS_NOT_MATCHED (SPROP_MARK | SPROP_IS_DUPLICATE)
JS_STATIC_DLL_CALLBACK(JSDHashNumber)
js_HashScopeProperty(JSDHashTable *table, const void *key)
{
const JSScopeProperty *sprop = (const JSScopeProperty *)key;
JSDHashNumber hash;
JSPropertyOp gsop;
/* Accumulate from least to most random so the low bits are most random. */
hash = 0;
gsop = sprop->getter;
if (gsop)
hash = (hash >> (JS_DHASH_BITS - 4)) ^ (hash << 4) ^ (jsword)gsop;
gsop = sprop->setter;
if (gsop)
hash = (hash >> (JS_DHASH_BITS - 4)) ^ (hash << 4) ^ (jsword)gsop;
hash = (hash >> (JS_DHASH_BITS - 4)) ^ (hash << 4)
^ (sprop->flags & ~SPROP_FLAGS_NOT_MATCHED);
hash = (hash >> (JS_DHASH_BITS - 4)) ^ (hash << 4) ^ sprop->attrs;
hash = (hash >> (JS_DHASH_BITS - 4)) ^ (hash << 4) ^ sprop->shortid;
hash = (hash >> (JS_DHASH_BITS - 4)) ^ (hash << 4) ^ sprop->slot;
hash = (hash >> (JS_DHASH_BITS - 4)) ^ (hash << 4) ^ sprop->id;
return hash;
}
#define SPROP_MATCH(sprop, child) \
SPROP_MATCH_PARAMS(sprop, (child)->id, (child)->getter, (child)->setter, \
(child)->slot, (child)->attrs, (child)->flags, \
(child)->shortid)
#define SPROP_MATCH_PARAMS(sprop, aid, agetter, asetter, aslot, aattrs, \
aflags, ashortid) \
((sprop)->id == (aid) && \
SPROP_MATCH_PARAMS_AFTER_ID(sprop, agetter, asetter, aslot, aattrs, \
aflags, ashortid))
#define SPROP_MATCH_PARAMS_AFTER_ID(sprop, agetter, asetter, aslot, aattrs, \
aflags, ashortid) \
((sprop)->getter == (agetter) && \
(sprop)->setter == (asetter) && \
(sprop)->slot == (aslot) && \
(sprop)->attrs == (aattrs) && \
(((sprop)->flags ^ (aflags)) & ~SPROP_FLAGS_NOT_MATCHED) == 0 && \
(sprop)->shortid == (ashortid))
JS_STATIC_DLL_CALLBACK(JSBool)
js_MatchScopeProperty(JSDHashTable *table,
const JSDHashEntryHdr *hdr,
const void *key)
{
const JSPropertyTreeEntry *entry = (const JSPropertyTreeEntry *)hdr;
const JSScopeProperty *sprop = entry->child;
const JSScopeProperty *kprop = (const JSScopeProperty *)key;
return SPROP_MATCH(sprop, kprop);
}
static const JSDHashTableOps PropertyTreeHashOps = {
JS_DHashAllocTable,
JS_DHashFreeTable,
JS_DHashGetKeyStub,
js_HashScopeProperty,
js_MatchScopeProperty,
JS_DHashMoveEntryStub,
JS_DHashClearEntryStub,
JS_DHashFinalizeStub,
NULL
};
/*
* A property tree node on rt->propertyFreeList overlays the following prefix
* struct on JSScopeProperty.
*/
typedef struct FreeNode {
jsid id;
JSScopeProperty *next;
JSScopeProperty **prevp;
} FreeNode;
#define FREENODE(sprop) ((FreeNode *) (sprop))
#define FREENODE_INSERT(list, sprop) \
JS_BEGIN_MACRO \
FREENODE(sprop)->next = (list); \
FREENODE(sprop)->prevp = &(list); \
if (list) \
FREENODE(list)->prevp = &FREENODE(sprop)->next; \
(list) = (sprop); \
JS_END_MACRO
#define FREENODE_REMOVE(sprop) \
JS_BEGIN_MACRO \
*FREENODE(sprop)->prevp = FREENODE(sprop)->next; \
if (FREENODE(sprop)->next) \
FREENODE(FREENODE(sprop)->next)->prevp = FREENODE(sprop)->prevp; \
JS_END_MACRO
/* NB: Called with the runtime lock held. */
static JSScopeProperty *
NewScopeProperty(JSRuntime *rt)
{
JSScopeProperty *sprop;
sprop = rt->propertyFreeList;
if (sprop) {
FREENODE_REMOVE(sprop);
} else {
JS_ARENA_ALLOCATE_CAST(sprop, JSScopeProperty *,
&rt->propertyArenaPool,
sizeof(JSScopeProperty));
if (!sprop)
return NULL;
}
JS_RUNTIME_METER(rt, livePropTreeNodes);
JS_RUNTIME_METER(rt, totalPropTreeNodes);
return sprop;
}
#define CHUNKY_KIDS_TAG ((jsuword)1)
#define KIDS_IS_CHUNKY(kids) ((jsuword)(kids) & CHUNKY_KIDS_TAG)
#define KIDS_TO_CHUNK(kids) ((PropTreeKidsChunk *) \
((jsuword)(kids) & ~CHUNKY_KIDS_TAG))
#define CHUNK_TO_KIDS(chunk) ((JSScopeProperty *) \
((jsuword)(chunk) | CHUNKY_KIDS_TAG))
#define MAX_KIDS_PER_CHUNK 10
typedef struct PropTreeKidsChunk PropTreeKidsChunk;
struct PropTreeKidsChunk {
JSScopeProperty *kids[MAX_KIDS_PER_CHUNK];
PropTreeKidsChunk *next;
};
static PropTreeKidsChunk *
NewPropTreeKidsChunk(JSRuntime *rt)
{
PropTreeKidsChunk *chunk;
chunk = calloc(1, sizeof *chunk);
if (!chunk)
return NULL;
JS_ASSERT(((jsuword)chunk & CHUNKY_KIDS_TAG) == 0);
JS_RUNTIME_METER(rt, propTreeKidsChunks);
return chunk;
}
static void
DestroyPropTreeKidsChunk(JSRuntime *rt, PropTreeKidsChunk *chunk)
{
JS_RUNTIME_UNMETER(rt, propTreeKidsChunks);
free(chunk);
}
/* NB: Called with the runtime lock held. */
static JSBool
InsertPropertyTreeChild(JSRuntime *rt, JSScopeProperty *parent,
JSScopeProperty *child, PropTreeKidsChunk *sweptChunk)
{
JSPropertyTreeEntry *entry;
JSScopeProperty **childp, *kids, *sprop;
PropTreeKidsChunk *chunk, **chunkp;
uintN i;
JS_ASSERT(!parent || child->parent != parent);
if (!parent) {
entry = (JSPropertyTreeEntry *)
JS_DHashTableOperate(&rt->propertyTreeHash, child, JS_DHASH_ADD);
if (!entry)
return JS_FALSE;
childp = &entry->child;
sprop = *childp;
if (!sprop) {
*childp = child;
} else {
/*
* A "Duplicate child" case.
*
* We can't do away with child, as at least one live scope entry
* still points at it. What's more, that scope's lastProp chains
* through an ancestor line to reach child, and js_Enumerate and
* others count on this linkage. We must leave child out of the
* hash table, and not require it to be there when we eventually
* GC it (see RemovePropertyTreeChild, below).
*
* It is necessary to leave the duplicate child out of the hash
* table to preserve entry uniqueness. It is safe to leave the
* child out of the hash table (unlike the duplicate child cases
* below), because the child's parent link will be null, which
* can't dangle.
*/
JS_ASSERT(sprop != child && SPROP_MATCH(sprop, child));
JS_RUNTIME_METER(rt, duplicatePropTreeNodes);
}
} else {
childp = &parent->kids;
kids = *childp;
if (kids) {
if (KIDS_IS_CHUNKY(kids)) {
chunk = KIDS_TO_CHUNK(kids);
do {
for (i = 0; i < MAX_KIDS_PER_CHUNK; i++) {
childp = &chunk->kids[i];
sprop = *childp;
if (!sprop)
goto insert;
JS_ASSERT(sprop != child);
if (SPROP_MATCH(sprop, child)) {
/*
* Duplicate child, see comment above. In this
* case, we must let the duplicate be inserted at
* this level in the tree, so we keep iterating,
* looking for an empty slot in which to insert.
*/
JS_ASSERT(sprop != child);
JS_RUNTIME_METER(rt, duplicatePropTreeNodes);
}
}
chunkp = &chunk->next;
} while ((chunk = *chunkp) != NULL);
if (sweptChunk) {
chunk = sweptChunk;
} else {
chunk = NewPropTreeKidsChunk(rt);
if (!chunk)
return JS_FALSE;
}
*chunkp = chunk;
childp = &chunk->kids[0];
} else {
sprop = kids;
JS_ASSERT(sprop != child);
if (SPROP_MATCH(sprop, child)) {
/*
* Duplicate child, see comment above. Once again, we
* must let duplicates created by deletion pile up in a
* kids-chunk-list, in order to find them when sweeping
* and thereby avoid dangling parent pointers.
*/
JS_RUNTIME_METER(rt, duplicatePropTreeNodes);
}
if (sweptChunk) {
chunk = sweptChunk;
} else {
chunk = NewPropTreeKidsChunk(rt);
if (!chunk)
return JS_FALSE;
}
parent->kids = CHUNK_TO_KIDS(chunk);
chunk->kids[0] = sprop;
childp = &chunk->kids[1];
}
}
insert:
*childp = child;
}
child->parent = parent;
return JS_TRUE;
}
/* NB: Called with the runtime lock held. */
static PropTreeKidsChunk *
RemovePropertyTreeChild(JSRuntime *rt, JSScopeProperty *child)
{
JSPropertyTreeEntry *entry;
JSScopeProperty *parent, *kids, *kid;
PropTreeKidsChunk *list, *chunk, **chunkp, *lastChunk;
uintN i, j;
parent = child->parent;
if (!parent) {
/*
* Don't remove child if it is not in rt->propertyTreeHash, but only
* matches a root child in the table that has compatible members. See
* the "Duplicate child" comments in InsertPropertyTreeChild, above.
*/
entry = (JSPropertyTreeEntry *)
JS_DHashTableOperate(&rt->propertyTreeHash, child, JS_DHASH_LOOKUP);
if (entry->child == child)
JS_DHashTableRawRemove(&rt->propertyTreeHash, &entry->hdr);
} else {
kids = parent->kids;
if (KIDS_IS_CHUNKY(kids)) {
list = chunk = KIDS_TO_CHUNK(kids);
chunkp = &list;
do {
for (i = 0; i < MAX_KIDS_PER_CHUNK; i++) {
if (chunk->kids[i] == child) {
lastChunk = chunk;
if (!lastChunk->next) {
j = i + 1;
} else {
j = 0;
do {
chunkp = &lastChunk->next;
lastChunk = *chunkp;
} while (lastChunk->next);
}
for (; j < MAX_KIDS_PER_CHUNK; j++) {
if (!lastChunk->kids[j])
break;
}
--j;
if (chunk != lastChunk || j > i)
chunk->kids[i] = lastChunk->kids[j];
lastChunk->kids[j] = NULL;
if (j == 0) {
*chunkp = NULL;
if (!list)
parent->kids = NULL;
return lastChunk;
}
return NULL;
}
}
chunkp = &chunk->next;
} while ((chunk = *chunkp) != NULL);
} else {
kid = kids;
if (kid == child)
parent->kids = NULL;
}
}
return NULL;
}
/*
* Called *without* the runtime lock held, this function acquires that lock
* only when inserting a new child. Thus there may be races to find or add
* a node that result in duplicates. We expect such races to be rare!
*/
static JSScopeProperty *
GetPropertyTreeChild(JSContext *cx, JSScopeProperty *parent,
JSScopeProperty *child)
{
JSRuntime *rt;
JSPropertyTreeEntry *entry;
JSScopeProperty *sprop;
PropTreeKidsChunk *chunk;
uintN i;
rt = cx->runtime;
if (!parent) {
JS_LOCK_RUNTIME(rt);
entry = (JSPropertyTreeEntry *)
JS_DHashTableOperate(&rt->propertyTreeHash, child, JS_DHASH_ADD);
if (!entry)
goto out_of_memory;
sprop = entry->child;
if (sprop)
goto out;
} else {
/*
* Because chunks are appended at the end and never deleted except by
* the GC, we can search without taking the runtime lock. We may miss
* a matching sprop added by another thread, and make a duplicate one,
* but that is an unlikely, therefore small, cost. The property tree
* has extremely low fan-out below its root in popular embeddings with
* real-world workloads.
*
* If workload changes so as to increase fan-out significantly below
* the property tree root, we'll want to add another tag bit stored in
* parent->kids that indicates a JSDHashTable pointer.
*/
entry = NULL;
sprop = parent->kids;
if (sprop) {
if (KIDS_IS_CHUNKY(sprop)) {
chunk = KIDS_TO_CHUNK(sprop);
do {
for (i = 0; i < MAX_KIDS_PER_CHUNK; i++) {
sprop = chunk->kids[i];
if (!sprop)
goto not_found;
if (SPROP_MATCH(sprop, child))
return sprop;
}
} while ((chunk = chunk->next) != NULL);
} else {
if (SPROP_MATCH(sprop, child))
return sprop;
}
}
not_found:
JS_LOCK_RUNTIME(rt);
}
sprop = NewScopeProperty(rt);
if (!sprop)
goto out_of_memory;
sprop->id = child->id;
sprop->getter = child->getter;
sprop->setter = child->setter;
sprop->slot = child->slot;
sprop->attrs = child->attrs;
sprop->flags = child->flags;
sprop->shortid = child->shortid;
sprop->parent = sprop->kids = NULL;
if (!parent) {
entry->child = sprop;
} else {
if (!InsertPropertyTreeChild(rt, parent, sprop, NULL))
goto out_of_memory;
}
out:
JS_UNLOCK_RUNTIME(rt);
return sprop;
out_of_memory:
JS_UNLOCK_RUNTIME(rt);
JS_ReportOutOfMemory(cx);
return NULL;
}
#ifdef DEBUG_notbrendan
#define CHECK_ANCESTOR_LINE(scope, sparse) \
JS_BEGIN_MACRO \
if ((scope)->table) CheckAncestorLine(scope, sparse); \
JS_END_MACRO
static void
CheckAncestorLine(JSScope *scope, JSBool sparse)
{
uint32 size;
JSScopeProperty **spp, **start, **end, *ancestorLine, *sprop, *aprop;
uint32 entryCount, ancestorCount;
ancestorLine = SCOPE_LAST_PROP(scope);
if (ancestorLine)
JS_ASSERT(SCOPE_HAS_PROPERTY(scope, ancestorLine));
entryCount = 0;
size = SCOPE_CAPACITY(scope);
start = scope->table;
for (spp = start, end = start + size; spp < end; spp++) {
sprop = SPROP_FETCH(spp);
if (sprop) {
entryCount++;
for (aprop = ancestorLine; aprop; aprop = aprop->parent) {
if (aprop == sprop)
break;
}
JS_ASSERT(aprop);
}
}
JS_ASSERT(entryCount == scope->entryCount);
ancestorCount = 0;
for (sprop = ancestorLine; sprop; sprop = sprop->parent) {
if (SCOPE_HAD_MIDDLE_DELETE(scope) &&
!SCOPE_HAS_PROPERTY(scope, sprop)) {
JS_ASSERT(sparse || (sprop->flags & SPROP_IS_DUPLICATE));
continue;
}
ancestorCount++;
}
JS_ASSERT(ancestorCount == scope->entryCount);
}
#else
#define CHECK_ANCESTOR_LINE(scope, sparse) /* nothing */
#endif
static void
ReportReadOnlyScope(JSContext *cx, JSScope *scope)
{
JSString *str;
str = js_ValueToString(cx, OBJECT_TO_JSVAL(scope->object));
JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL, JSMSG_READ_ONLY,
str
? JS_GetStringBytes(str)
: LOCKED_OBJ_GET_CLASS(scope->object)->name);
}
JSScopeProperty *
js_AddScopeProperty(JSContext *cx, JSScope *scope, jsid id,
JSPropertyOp getter, JSPropertyOp setter, uint32 slot,
uintN attrs, uintN flags, intN shortid)
{
JSScopeProperty **spp, *sprop, *overwriting, **spvec, **spp2, child;
uint32 size, splen, i;
int change;
JSTempValueRooter tvr;
JS_ASSERT(JS_IS_SCOPE_LOCKED(cx, scope));
CHECK_ANCESTOR_LINE(scope, JS_TRUE);
/*
* You can't add properties to a sealed scope. But note well that you can
* change property attributes in a sealed scope, even though that replaces
* a JSScopeProperty * in the scope's hash table -- but no id is added, so
* the scope remains sealed.
*/
if (SCOPE_IS_SEALED(scope)) {
ReportReadOnlyScope(cx, scope);
return NULL;
}
/*
* Normalize stub getter and setter values for faster is-stub testing in
* the SPROP_CALL_[GS]ETTER macros.
*/
if (getter == JS_PropertyStub)
getter = NULL;
if (setter == JS_PropertyStub)
setter = NULL;
/*
* Search for id in order to claim its entry, allocating a property tree
* node if one doesn't already exist for our parameters.
*/
spp = js_SearchScope(scope, id, JS_TRUE);
sprop = overwriting = SPROP_FETCH(spp);
if (!sprop) {
/* Check whether we need to grow, if the load factor is >= .75. */
size = SCOPE_CAPACITY(scope);
if (scope->entryCount + scope->removedCount >= size - (size >> 2)) {
if (scope->removedCount >= size >> 2) {
METER(compresses);
change = 0;
} else {
METER(grows);
change = 1;
}
if (!ChangeScope(cx, scope, change) &&
scope->entryCount + scope->removedCount == size - 1) {
METER(addFailures);
return NULL;
}
spp = js_SearchScope(scope, id, JS_TRUE);
JS_ASSERT(!SPROP_FETCH(spp));
}
} else {
/* Property exists: js_SearchScope must have returned a valid entry. */
JS_ASSERT(!SPROP_IS_REMOVED(*spp));
/*
* If all property members match, this is a redundant add and we can
* return early. If the caller wants to allocate a slot, but doesn't
* care which slot, copy sprop->slot into slot so we can match sprop,
* if all other members match.
*/
if (!(attrs & JSPROP_SHARED) &&
slot == SPROP_INVALID_SLOT &&
SPROP_HAS_VALID_SLOT(sprop, scope)) {
slot = sprop->slot;
}
if (SPROP_MATCH_PARAMS_AFTER_ID(sprop, getter, setter, slot, attrs,
flags, shortid)) {
METER(redundantAdds);
return sprop;
}
/*
* Duplicate formal parameters require us to leave the old property
* on the ancestor line, so the decompiler can find it, even though
* its entry in scope->table is overwritten to point at a new property
* descending from the old one. The SPROP_IS_DUPLICATE flag helps us
* cope with the consequent disparity between ancestor line height and
* scope->entryCount.
*/
if (flags & SPROP_IS_DUPLICATE) {
sprop->flags |= SPROP_IS_DUPLICATE;
} else {
/*
* If we are clearing sprop to force an existing property to be
* overwritten (apart from a duplicate formal parameter), we must
* unlink it from the ancestor line at scope->lastProp, lazily if
* sprop is not lastProp. And we must remove the entry at *spp,
* precisely so the lazy "middle delete" fixup code further below
* won't find sprop in scope->table, in spite of sprop being on
* the ancestor line.
*
* When we finally succeed in finding or creating a new sprop
* and storing its pointer at *spp, we'll use the |overwriting|
* local saved when we first looked up id to decide whether we're
* indeed creating a new entry, or merely overwriting an existing
* property.
*/
if (sprop == SCOPE_LAST_PROP(scope)) {
do {
SCOPE_REMOVE_LAST_PROP(scope);
if (!SCOPE_HAD_MIDDLE_DELETE(scope))
break;
sprop = SCOPE_LAST_PROP(scope);
} while (sprop && !SCOPE_HAS_PROPERTY(scope, sprop));
} else if (!SCOPE_HAD_MIDDLE_DELETE(scope)) {
/*
* If we have no hash table yet, we need one now. The middle
* delete code is simple-minded that way!
*/
if (!scope->table) {
if (!CreateScopeTable(cx, scope, JS_TRUE))
return NULL;
spp = js_SearchScope(scope, id, JS_TRUE);
sprop = overwriting = SPROP_FETCH(spp);
}
SCOPE_SET_MIDDLE_DELETE(scope);
}
}
/*
* If we fail later on trying to find or create a new sprop, we will
* goto fail_overwrite and restore *spp from |overwriting|. Note that
* we don't bother to keep scope->removedCount in sync, because we'll
* fix up *spp and scope->entryCount shortly, no matter how control