The Tor Browser: comparison js/src/jsatom.cpp

--1:000000000000
+:f7bc97252ffe
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+* vim: set ts=8 sts=4 et sw=4 tw=99:
+* This Source Code Form is subject to the terms of the Mozilla Public
+* License, v. 2.0. If a copy of the MPL was not distributed with this
+* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+/*
+* JS atom table.
+*/
+#include "jsatominlines.h"
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/RangedPtr.h"
+#include <string.h>
+#include "jscntxt.h"
+#include "jsstr.h"
+#include "jstypes.h"
+#include "gc/Marking.h"
+#include "vm/Xdr.h"
+#include "jscntxtinlines.h"
+#include "jscompartmentinlines.h"
+#include "jsobjinlines.h"
+#include "vm/String-inl.h"
+using namespace js;
+using namespace js::gc;
+using mozilla::ArrayEnd;
+using mozilla::ArrayLength;
+using mozilla::RangedPtr;
+const char *
+js::AtomToPrintableString(ExclusiveContext *cx, JSAtom *atom, JSAutoByteString *bytes)
+{
+JSString *str = js_QuoteString(cx, atom, 0);
+if (!str)
+return nullptr;
+return bytes->encodeLatin1(cx, str);
+}
+const char * const js::TypeStrings[] = {
+js_undefined_str,
+js_object_str,
+js_function_str,
+js_string_str,
+js_number_str,
+js_boolean_str,
+js_null_str,
+};
+#define DEFINE_PROTO_STRING(name,code,init,clasp) const char js_##name##_str[] = #name;
+JS_FOR_EACH_PROTOTYPE(DEFINE_PROTO_STRING)
+#undef DEFINE_PROTO_STRING
+#define CONST_CHAR_STR(idpart, id, text) const char js_##idpart##_str[] = text;
+FOR_EACH_COMMON_PROPERTYNAME(CONST_CHAR_STR)
+#undef CONST_CHAR_STR
+/* Constant strings that are not atomized. */
+const char js_break_str[]           = "break";
+const char js_case_str[]            = "case";
+const char js_catch_str[]           = "catch";
+const char js_class_str[]           = "class";
+const char js_close_str[]           = "close";
+const char js_const_str[]           = "const";
+const char js_continue_str[]        = "continue";
+const char js_debugger_str[]        = "debugger";
+const char js_default_str[]         = "default";
+const char js_do_str[]              = "do";
+const char js_else_str[]            = "else";
+const char js_enum_str[]            = "enum";
+const char js_export_str[]          = "export";
+const char js_extends_str[]         = "extends";
+const char js_finally_str[]         = "finally";
+const char js_for_str[]             = "for";
+const char js_getter_str[]          = "getter";
+const char js_if_str[]              = "if";
+const char js_implements_str[]      = "implements";
+const char js_import_str[]          = "import";
+const char js_in_str[]              = "in";
+const char js_instanceof_str[]      = "instanceof";
+const char js_interface_str[]       = "interface";
+const char js_new_str[]             = "new";
+const char js_package_str[]         = "package";
+const char js_private_str[]         = "private";
+const char js_protected_str[]       = "protected";
+const char js_public_str[]          = "public";
+const char js_send_str[]            = "send";
+const char js_setter_str[]          = "setter";
+const char js_static_str[]          = "static";
+const char js_super_str[]           = "super";
+const char js_switch_str[]          = "switch";
+const char js_this_str[]            = "this";
+const char js_try_str[]             = "try";
+const char js_typeof_str[]          = "typeof";
+const char js_void_str[]            = "void";
+const char js_while_str[]           = "while";
+const char js_with_str[]            = "with";
+// Use a low initial capacity for atom hash tables to avoid penalizing runtimes
+// which create a small number of atoms.
+static const uint32_t JS_STRING_HASH_COUNT = 64;
+struct CommonNameInfo
+{
+const char *str;
+size_t length;
+};
+bool
+JSRuntime::initializeAtoms(JSContext *cx)
+{
+atoms_ = cx->new_<AtomSet>();
+if (!atoms_ || !atoms_->init(JS_STRING_HASH_COUNT))
+return false;
+if (parentRuntime) {
+staticStrings = parentRuntime->staticStrings;
+commonNames = parentRuntime->commonNames;
+emptyString = parentRuntime->emptyString;
+permanentAtoms = parentRuntime->permanentAtoms;
+return true;
+}
+permanentAtoms = cx->new_<AtomSet>();
+if (!permanentAtoms || !permanentAtoms->init(JS_STRING_HASH_COUNT))
+return false;
+staticStrings = cx->new_<StaticStrings>();
+if (!staticStrings || !staticStrings->init(cx))
+return false;
+static const CommonNameInfo cachedNames[] = {
+#define COMMON_NAME_INFO(idpart, id, text) { js_##idpart##_str, sizeof(text) - 1 },
+FOR_EACH_COMMON_PROPERTYNAME(COMMON_NAME_INFO)
+#undef COMMON_NAME_INFO
+#define COMMON_NAME_INFO(name, code, init, clasp) { js_##name##_str, sizeof(#name) - 1 },
+JS_FOR_EACH_PROTOTYPE(COMMON_NAME_INFO)
+#undef COMMON_NAME_INFO
+};
+commonNames = cx->new_<JSAtomState>();
+if (!commonNames)
+return false;
+FixedHeapPtr<PropertyName> *names = reinterpret_cast<FixedHeapPtr<PropertyName> *>(commonNames);
+for (size_t i = 0; i < ArrayLength(cachedNames); i++, names++) {
+JSAtom *atom = Atomize(cx, cachedNames[i].str, cachedNames[i].length, InternAtom);
+if (!atom)
+return false;
+names->init(atom->asPropertyName());
+}
+JS_ASSERT(uintptr_t(names) == uintptr_t(commonNames + 1));
+emptyString = commonNames->empty;
+return true;
+}
+void
+JSRuntime::finishAtoms()
+{
+if (atoms_)
+js_delete(atoms_);
+if (!parentRuntime) {
+if (staticStrings)
+js_delete(staticStrings);
+if (commonNames)
+js_delete(commonNames);
+if (permanentAtoms)
+js_delete(permanentAtoms);
+}
+atoms_ = nullptr;
+staticStrings = nullptr;
+commonNames = nullptr;
+permanentAtoms = nullptr;
+emptyString = nullptr;
+}
+void
+js::MarkAtoms(JSTracer *trc)
+{
+JSRuntime *rt = trc->runtime();
+for (AtomSet::Enum e(rt->atoms()); !e.empty(); e.popFront()) {
+const AtomStateEntry &entry = e.front();
+if (!entry.isTagged())
+continue;
+JSAtom *atom = entry.asPtr();
+bool tagged = entry.isTagged();
+MarkStringRoot(trc, &atom, "interned_atom");
+if (entry.asPtr() != atom)
+e.rekeyFront(AtomHasher::Lookup(atom), AtomStateEntry(atom, tagged));
+}
+}
+void
+js::MarkPermanentAtoms(JSTracer *trc)
+{
+JSRuntime *rt = trc->runtime();
+// Permanent atoms only need to be marked in the runtime which owns them.
+if (rt->parentRuntime)
+return;
+// Static strings are not included in the permanent atoms table.
+if (rt->staticStrings)
+rt->staticStrings->trace(trc);
+if (rt->permanentAtoms) {
+for (AtomSet::Enum e(*rt->permanentAtoms); !e.empty(); e.popFront()) {
+const AtomStateEntry &entry = e.front();
+JSAtom *atom = entry.asPtr();
+MarkPermanentAtom(trc, atom, "permanent_table");
+}
+}
+}
+void
+JSRuntime::sweepAtoms()
+{
+if (!atoms_)
+return;
+for (AtomSet::Enum e(*atoms_); !e.empty(); e.popFront()) {
+AtomStateEntry entry = e.front();
+JSAtom *atom = entry.asPtr();
+bool isDying = IsStringAboutToBeFinalized(&atom);
+/* Pinned or interned key cannot be finalized. */
+JS_ASSERT_IF(hasContexts() && entry.isTagged(), !isDying);
+if (isDying)
+e.removeFront();
+}
+}
+bool
+JSRuntime::transformToPermanentAtoms()
+{
+JS_ASSERT(!parentRuntime);
+// All static strings were created as permanent atoms, now move the contents
+// of the atoms table into permanentAtoms and mark each as permanent.
+JS_ASSERT(permanentAtoms && permanentAtoms->empty());
+AtomSet *temp = atoms_;
+atoms_ = permanentAtoms;
+permanentAtoms = temp;
+for (AtomSet::Enum e(*permanentAtoms); !e.empty(); e.popFront()) {
+AtomStateEntry entry = e.front();
+JSAtom *atom = entry.asPtr();
+atom->morphIntoPermanentAtom();
+}
+return true;
+}
+bool
+AtomIsInterned(JSContext *cx, JSAtom *atom)
+{
+/* We treat static strings as interned because they're never collected. */
+if (StaticStrings::isStatic(atom))
+return true;
+AtomHasher::Lookup lookup(atom);
+/* Likewise, permanent strings are considered to be interned. */
+AtomSet::Ptr p = cx->permanentAtoms().readonlyThreadsafeLookup(lookup);
+if (p)
+return true;
+AutoLockForExclusiveAccess lock(cx);
+p = cx->runtime()->atoms().lookup(lookup);
+if (!p)
+return false;
+return p->isTagged();
+}
+/*
+* When the jschars reside in a freshly allocated buffer the memory can be used
+* as a new JSAtom's storage without copying. The contract is that the caller no
+* longer owns the memory and this method is responsible for freeing the memory.
+*/
+MOZ_ALWAYS_INLINE
+static JSAtom *
+AtomizeAndtake(ExclusiveContext *cx, jschar *tbchars, size_t length, InternBehavior ib)
+{
+JS_ASSERT(tbchars[length] == 0);
+if (JSAtom *s = cx->staticStrings().lookup(tbchars, length)) {
+js_free(tbchars);
+return s;
+}
+AtomHasher::Lookup lookup(tbchars, length);
+AtomSet::Ptr pp = cx->permanentAtoms().readonlyThreadsafeLookup(lookup);
+if (pp) {
+js_free(tbchars);
+return pp->asPtr();
+}
+AutoLockForExclusiveAccess lock(cx);
+/*
+* If a GC occurs at js_NewStringCopy then |p| will still have the correct
+* hash, allowing us to avoid rehashing it. Even though the hash is
+* unchanged, we need to re-lookup the table position because a last-ditch
+* GC will potentially free some table entries.
+*/
+AtomSet& atoms = cx->atoms();
+AtomSet::AddPtr p = atoms.lookupForAdd(lookup);
+if (p) {
+JSAtom *atom = p->asPtr();
+p->setTagged(bool(ib));
+js_free(tbchars);
+return atom;
+}
+AutoCompartment ac(cx, cx->atomsCompartment());
+JSFlatString *flat = js_NewString<NoGC>(cx, tbchars, length);
+if (!flat) {
+js_free(tbchars);
+js_ReportOutOfMemory(cx);
+return nullptr;
+}
+JSAtom *atom = flat->morphAtomizedStringIntoAtom();
+if (!atoms.relookupOrAdd(p, lookup, AtomStateEntry(atom, bool(ib)))) {
+js_ReportOutOfMemory(cx); /* SystemAllocPolicy does not report OOM. */
+return nullptr;
+}
+return atom;
+}
+/* |tbchars| must not point into an inline or short string. */
+MOZ_ALWAYS_INLINE
+static JSAtom *
+AtomizeAndCopyChars(ExclusiveContext *cx, const jschar *tbchars, size_t length, InternBehavior ib)
+{
+if (JSAtom *s = cx->staticStrings().lookup(tbchars, length))
+return s;
+AtomHasher::Lookup lookup(tbchars, length);
+AtomSet::Ptr pp = cx->permanentAtoms().readonlyThreadsafeLookup(lookup);
+if (pp)
+return pp->asPtr();
+/*
+* If a GC occurs at js_NewStringCopy then |p| will still have the correct
+* hash, allowing us to avoid rehashing it. Even though the hash is
+* unchanged, we need to re-lookup the table position because a last-ditch
+* GC will potentially free some table entries.
+*/
+AutoLockForExclusiveAccess lock(cx);
+AtomSet& atoms = cx->atoms();
+AtomSet::AddPtr p = atoms.lookupForAdd(lookup);
+if (p) {
+JSAtom *atom = p->asPtr();
+p->setTagged(bool(ib));
+return atom;
+}
+AutoCompartment ac(cx, cx->atomsCompartment());
+JSFlatString *flat = js_NewStringCopyN<NoGC>(cx, tbchars, length);
+if (!flat) {
+js_ReportOutOfMemory(cx);
+return nullptr;
+}
+JSAtom *atom = flat->morphAtomizedStringIntoAtom();
+if (!atoms.relookupOrAdd(p, lookup, AtomStateEntry(atom, bool(ib)))) {
+js_ReportOutOfMemory(cx); /* SystemAllocPolicy does not report OOM. */
+return nullptr;
+}
+return atom;
+}
+JSAtom *
+js::AtomizeString(ExclusiveContext *cx, JSString *str,
+js::InternBehavior ib /* = js::DoNotInternAtom */)
+{
+if (str->isAtom()) {
+JSAtom &atom = str->asAtom();
+/* N.B. static atoms are effectively always interned. */
+if (ib != InternAtom || js::StaticStrings::isStatic(&atom))
+return &atom;
+AtomHasher::Lookup lookup(&atom);
+/* Likewise, permanent atoms are always interned. */
+AtomSet::Ptr p = cx->permanentAtoms().readonlyThreadsafeLookup(lookup);
+if (p)
+return &atom;
+AutoLockForExclusiveAccess lock(cx);
+p = cx->atoms().lookup(lookup);
+JS_ASSERT(p); /* Non-static atom must exist in atom state set. */
+JS_ASSERT(p->asPtr() == &atom);
+JS_ASSERT(ib == InternAtom);
+p->setTagged(bool(ib));
+return &atom;
+}
+const jschar *chars = str->getChars(cx);
+if (!chars)
+return nullptr;
+return AtomizeAndCopyChars(cx, chars, str->length(), ib);
+}
+JSAtom *
+js::Atomize(ExclusiveContext *cx, const char *bytes, size_t length, InternBehavior ib)
+{
+CHECK_REQUEST(cx);
+if (!JSString::validateLength(cx, length))
+return nullptr;
+static const unsigned ATOMIZE_BUF_MAX = 32;
+if (length < ATOMIZE_BUF_MAX) {
+/*
+* Avoiding the malloc in InflateString on shorter strings saves us
+* over 20,000 malloc calls on mozilla browser startup. This compares to
+* only 131 calls where the string is longer than a 31 char (net) buffer.
+* The vast majority of atomized strings are already in the hashtable. So
+* js::AtomizeString rarely has to copy the temp string we make.
+*/
+jschar inflated[ATOMIZE_BUF_MAX];
+InflateStringToBuffer(bytes, length, inflated);
+return AtomizeAndCopyChars(cx, inflated, length, ib);
+}
+jschar *tbcharsZ = InflateString(cx, bytes, &length);
+if (!tbcharsZ)
+return nullptr;
+return AtomizeAndtake(cx, tbcharsZ, length, ib);
+}
+JSAtom *
+js::AtomizeChars(ExclusiveContext *cx, const jschar *chars, size_t length, InternBehavior ib)
+{
+CHECK_REQUEST(cx);
+if (!JSString::validateLength(cx, length))
+return nullptr;
+return AtomizeAndCopyChars(cx, chars, length, ib);
+}
+bool
+js::IndexToIdSlow(ExclusiveContext *cx, uint32_t index, MutableHandleId idp)
+{
+JS_ASSERT(index > JSID_INT_MAX);
+jschar buf[UINT32_CHAR_BUFFER_LENGTH];
+RangedPtr<jschar> end(ArrayEnd(buf), buf, ArrayEnd(buf));
+RangedPtr<jschar> start = BackfillIndexInCharBuffer(index, end);
+JSAtom *atom = AtomizeChars(cx, start.get(), end - start);
+if (!atom)
+return false;
+idp.set(JSID_FROM_BITS((size_t)atom));
+return true;
+}
+template <AllowGC allowGC>
+static JSAtom *
+ToAtomSlow(ExclusiveContext *cx, typename MaybeRooted<Value, allowGC>::HandleType arg)
+{
+JS_ASSERT(!arg.isString());
+Value v = arg;
+if (!v.isPrimitive()) {
+if (!cx->shouldBeJSContext() || !allowGC)
+return nullptr;
+RootedValue v2(cx, v);
+if (!ToPrimitive(cx->asJSContext(), JSTYPE_STRING, &v2))
+return nullptr;
+v = v2;
+}
+if (v.isString())
+return AtomizeString(cx, v.toString());
+if (v.isInt32())
+return Int32ToAtom(cx, v.toInt32());
+if (v.isDouble())
+return NumberToAtom(cx, v.toDouble());
+if (v.isBoolean())
+return v.toBoolean() ? cx->names().true_ : cx->names().false_;
+if (v.isNull())
+return cx->names().null;
+return cx->names().undefined;
+}
+template <AllowGC allowGC>
+JSAtom *
+js::ToAtom(ExclusiveContext *cx, typename MaybeRooted<Value, allowGC>::HandleType v)
+{
+if (!v.isString())
+return ToAtomSlow<allowGC>(cx, v);
+JSString *str = v.toString();
+if (str->isAtom())
+return &str->asAtom();
+return AtomizeString(cx, str);
+}
+template JSAtom *
+js::ToAtom<CanGC>(ExclusiveContext *cx, HandleValue v);
+template JSAtom *
+js::ToAtom<NoGC>(ExclusiveContext *cx, Value v);
+template<XDRMode mode>
+bool
+js::XDRAtom(XDRState<mode> *xdr, MutableHandleAtom atomp)
+{
+if (mode == XDR_ENCODE) {
+uint32_t nchars = atomp->length();
+if (!xdr->codeUint32(&nchars))
+return false;
+jschar *chars = const_cast<jschar *>(atomp->getChars(xdr->cx()));
+if (!chars)
+return false;
+return xdr->codeChars(chars, nchars);
+}
+/* Avoid JSString allocation for already existing atoms. See bug 321985. */
+uint32_t nchars;
+if (!xdr->codeUint32(&nchars))
+return false;
+JSContext *cx = xdr->cx();
+JSAtom *atom;
+#if IS_LITTLE_ENDIAN
+/* Directly access the little endian chars in the XDR buffer. */
+const jschar *chars = reinterpret_cast<const jschar *>(xdr->buf.read(nchars * sizeof(jschar)));
+atom = AtomizeChars(cx, chars, nchars);
+#else
+/*
+* We must copy chars to a temporary buffer to convert between little and
+* big endian data.
+*/
+jschar *chars;
+jschar stackChars[256];
+if (nchars <= ArrayLength(stackChars)) {
+chars = stackChars;
+} else {
+/*
+* This is very uncommon. Don't use the tempLifoAlloc arena for this as
+* most allocations here will be bigger than tempLifoAlloc's default
+* chunk size.
+*/
+chars = cx->runtime()->pod_malloc<jschar>(nchars);
+if (!chars)
+return false;
+}
+JS_ALWAYS_TRUE(xdr->codeChars(chars, nchars));
+atom = AtomizeChars(cx, chars, nchars);
+if (chars != stackChars)
+js_free(chars);
+#endif /* !IS_LITTLE_ENDIAN */
+if (!atom)
+return false;
+atomp.set(atom);
+return true;
+}
+template bool
+js::XDRAtom(XDRState<XDR_ENCODE> *xdr, MutableHandleAtom atomp);
+template bool
+js::XDRAtom(XDRState<XDR_DECODE> *xdr, MutableHandleAtom atomp);

The Tor Browser / file comparison

comparison: js/src/jsatom.cpp

js/src/jsatom.cpp