The Tor Browser: js/src/jsatom.cpp@b8a032363ba2 (annotated)

js/src/jsatom.cpp@b8a032363ba2 (annotated)

js/src/jsatom.cpp

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* -*- 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 / annotate

js/src/jsatom.cpp@b8a032363ba2 (annotated)

js/src/jsatom.cpp