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gecko-dev/xpcom/ds/nsAtomTable.cpp

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
// vim:cindent:ts=2:et:sw=2:
/* ***** 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.org code.
*
* 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 ***** */
#include "nsAtomTable.h"
#include "nsStaticAtom.h"
#include "nsString.h"
#include "nsReadableUtils.h"
#include "nsUTF8Utils.h"
#include "nsCRT.h"
#include "pldhash.h"
#include "prenv.h"
#include "nsThreadUtils.h"
#include "nsDataHashtable.h"
#include "nsHashKeys.h"
#include "nsAutoPtr.h"
#define PL_ARENA_CONST_ALIGN_MASK 3
#include "plarena.h"
/**
* The shared hash table for atom lookups.
*
* XXX This should be manipulated in a threadsafe way or we should make
* sure it's only manipulated from the main thread. Probably the latter
* is better, since the former would hurt performance.
*
* If |gAtomTable.ops| is 0, then the table is uninitialized.
*/
static PLDHashTable gAtomTable;
/**
* A hashtable of static atoms that existed at app startup. This hashtable helps
* nsHtml5AtomTable.
*/
static nsDataHashtable<nsStringHashKey, nsIAtom*>* gStaticAtomTable = 0;
/**
* Whether it is still OK to add atoms to gStaticAtomTable.
*/
static PRBool gStaticAtomTableSealed = PR_FALSE;
//----------------------------------------------------------------------
struct AtomTableEntry : public PLDHashEntryHdr {
AtomImpl* mAtom;
};
struct AtomTableKey
{
AtomTableKey(const PRUnichar* aUTF16String, PRUint32 aLength)
: mUTF16String(aUTF16String),
mUTF8String(nsnull),
mLength(aLength)
{
}
AtomTableKey(const char* aUTF8String, PRUint32 aLength)
: mUTF16String(nsnull),
mUTF8String(aUTF8String),
mLength(aLength)
{
}
const PRUnichar* mUTF16String;
const char* mUTF8String;
PRUint32 mLength;
};
static PLDHashNumber
AtomTableGetHash(PLDHashTable *table, const void *key)
{
const AtomTableKey *k = static_cast<const AtomTableKey*>(key);
if (k->mUTF8String) {
PRBool err;
PRUint32 hash = nsCRT::HashCodeAsUTF16(k->mUTF8String, k->mLength, &err);
if (err) {
AtomTableKey* mutableKey = const_cast<AtomTableKey*>(k);
mutableKey->mUTF8String = nsnull;
mutableKey->mLength = 0;
hash = 0;
}
return hash;
}
return nsCRT::HashCode(k->mUTF16String, k->mLength);
}
static PRBool
AtomTableMatchKey(PLDHashTable *table, const PLDHashEntryHdr *entry,
const void *key)
{
const AtomTableEntry *he = static_cast<const AtomTableEntry*>(entry);
const AtomTableKey *k = static_cast<const AtomTableKey*>(key);
if (k->mUTF8String) {
return
CompareUTF8toUTF16(nsDependentCSubstring(k->mUTF8String,
k->mUTF8String + k->mLength),
nsDependentAtomString(he->mAtom)) == 0;
}
PRUint32 length = he->mAtom->GetLength();
if (length != k->mLength) {
return PR_FALSE;
}
return memcmp(he->mAtom->GetUTF16String(),
k->mUTF16String, length * sizeof(PRUnichar)) == 0;
}
static void
AtomTableClearEntry(PLDHashTable *table, PLDHashEntryHdr *entry)
{
// Normal |AtomImpl| atoms are deleted when their refcount hits 0, and
// they then remove themselves from the table. In other words, they
// are owned by the callers who own references to them.
// |PermanentAtomImpl| permanent atoms ignore their refcount and are
// deleted when they are removed from the table at table destruction.
// In other words, they are owned by the atom table.
AtomImpl *atom = static_cast<AtomTableEntry*>(entry)->mAtom;
if (atom->IsPermanent()) {
// Note that the cast here is important since AtomImpls doesn't have a
// virtual dtor.
delete static_cast<PermanentAtomImpl*>(atom);
}
}
static PRBool
AtomTableInitEntry(PLDHashTable *table, PLDHashEntryHdr *entry,
const void *key)
{
static_cast<AtomTableEntry*>(entry)->mAtom = nsnull;
return PR_TRUE;
}
static const PLDHashTableOps AtomTableOps = {
PL_DHashAllocTable,
PL_DHashFreeTable,
AtomTableGetHash,
AtomTableMatchKey,
PL_DHashMoveEntryStub,
AtomTableClearEntry,
PL_DHashFinalizeStub,
AtomTableInitEntry
};
#ifdef DEBUG
static PLDHashOperator
DumpAtomLeaks(PLDHashTable *table, PLDHashEntryHdr *he,
PRUint32 index, void *arg)
{
AtomTableEntry *entry = static_cast<AtomTableEntry*>(he);
AtomImpl* atom = entry->mAtom;
if (!atom->IsPermanent()) {
++*static_cast<PRUint32*>(arg);
nsCAutoString str;
atom->ToUTF8String(str);
fputs(str.get(), stdout);
fputs("\n", stdout);
}
return PL_DHASH_NEXT;
}
#endif
static inline
void PromoteToPermanent(AtomImpl* aAtom)
{
#ifdef NS_BUILD_REFCNT_LOGGING
{
nsrefcnt refcount = aAtom->GetRefCount();
do {
NS_LOG_RELEASE(aAtom, --refcount, "AtomImpl");
} while (refcount);
}
#endif
aAtom = new (aAtom) PermanentAtomImpl();
}
void
NS_PurgeAtomTable()
{
delete gStaticAtomTable;
if (gAtomTable.ops) {
#ifdef DEBUG
const char *dumpAtomLeaks = PR_GetEnv("MOZ_DUMP_ATOM_LEAKS");
if (dumpAtomLeaks && *dumpAtomLeaks) {
PRUint32 leaked = 0;
printf("*** %d atoms still exist (including permanent):\n",
gAtomTable.entryCount);
PL_DHashTableEnumerate(&gAtomTable, DumpAtomLeaks, &leaked);
printf("*** %u non-permanent atoms leaked\n", leaked);
}
#endif
PL_DHashTableFinish(&gAtomTable);
gAtomTable.entryCount = 0;
gAtomTable.ops = nsnull;
}
}
AtomImpl::AtomImpl(const nsAString& aString)
{
mLength = aString.Length();
nsStringBuffer* buf = nsStringBuffer::FromString(aString);
if (buf) {
buf->AddRef();
mString = static_cast<PRUnichar*>(buf->Data());
}
else {
buf = nsStringBuffer::Alloc((mLength + 1) * sizeof(PRUnichar));
mString = static_cast<PRUnichar*>(buf->Data());
CopyUnicodeTo(aString, 0, mString, mLength);
mString[mLength] = PRUnichar(0);
}
NS_ASSERTION(mString[mLength] == PRUnichar(0), "null terminated");
NS_ASSERTION(buf && buf->StorageSize() >= (mLength+1) * sizeof(PRUnichar),
"enough storage");
NS_ASSERTION(Equals(aString), "correct data");
}
AtomImpl::AtomImpl(nsStringBuffer* aStringBuffer, PRUint32 aLength)
{
mLength = aLength;
mString = static_cast<PRUnichar*>(aStringBuffer->Data());
// Technically we could currently avoid doing this addref by instead making
// the static atom buffers have an initial refcount of 2.
aStringBuffer->AddRef();
NS_ASSERTION(mString[mLength] == PRUnichar(0), "null terminated");
NS_ASSERTION(aStringBuffer &&
aStringBuffer->StorageSize() == (mLength+1) * sizeof(PRUnichar),
"correct storage");
}
AtomImpl::~AtomImpl()
{
NS_PRECONDITION(gAtomTable.ops, "uninitialized atom hashtable");
// Permanent atoms are removed from the hashtable at shutdown, and we
// don't want to remove them twice. See comment above in
// |AtomTableClearEntry|.
if (!IsPermanentInDestructor()) {
AtomTableKey key(mString, mLength);
PL_DHashTableOperate(&gAtomTable, &key, PL_DHASH_REMOVE);
if (gAtomTable.entryCount == 0) {
PL_DHashTableFinish(&gAtomTable);
NS_ASSERTION(gAtomTable.entryCount == 0,
"PL_DHashTableFinish changed the entry count");
}
}
nsStringBuffer::FromData(mString)->Release();
}
NS_IMPL_ISUPPORTS1(AtomImpl, nsIAtom)
PermanentAtomImpl::~PermanentAtomImpl()
{
// So we can tell if we were permanent while running the base class dtor.
mRefCnt = REFCNT_PERMANENT_SENTINEL;
}
NS_IMETHODIMP_(nsrefcnt) PermanentAtomImpl::AddRef()
{
NS_ASSERTION(NS_IsMainThread(), "wrong thread");
return 2;
}
NS_IMETHODIMP_(nsrefcnt) PermanentAtomImpl::Release()
{
NS_ASSERTION(NS_IsMainThread(), "wrong thread");
return 1;
}
/* virtual */ PRBool
AtomImpl::IsPermanent()
{
return PR_FALSE;
}
/* virtual */ PRBool
PermanentAtomImpl::IsPermanent()
{
return PR_TRUE;
}
void* PermanentAtomImpl::operator new ( size_t size, AtomImpl* aAtom ) CPP_THROW_NEW {
NS_ASSERTION(!aAtom->IsPermanent(),
"converting atom that's already permanent");
// Just let the constructor overwrite the vtable pointer.
return aAtom;
}
NS_IMETHODIMP
AtomImpl::ScriptableToString(nsAString& aBuf)
{
nsStringBuffer::FromData(mString)->ToString(mLength, aBuf);
return NS_OK;
}
NS_IMETHODIMP
AtomImpl::ToUTF8String(nsACString& aBuf)
{
CopyUTF16toUTF8(nsDependentString(mString, mLength), aBuf);
return NS_OK;
}
NS_IMETHODIMP_(PRBool)
AtomImpl::EqualsUTF8(const nsACString& aString)
{
return CompareUTF8toUTF16(aString,
nsDependentString(mString, mLength)) == 0;
}
NS_IMETHODIMP
AtomImpl::ScriptableEquals(const nsAString& aString, PRBool* aResult)
{
*aResult = aString.Equals(nsDependentString(mString, mLength));
return NS_OK;
}
NS_IMETHODIMP_(PRBool)
AtomImpl::IsStaticAtom()
{
return IsPermanent();
}
//----------------------------------------------------------------------
#define ATOM_HASHTABLE_INITIAL_SIZE 4096
static inline AtomTableEntry*
GetAtomHashEntry(const char* aString, PRUint32 aLength)
{
NS_ASSERTION(NS_IsMainThread(), "wrong thread");
if (!gAtomTable.ops &&
!PL_DHashTableInit(&gAtomTable, &AtomTableOps, 0,
sizeof(AtomTableEntry), ATOM_HASHTABLE_INITIAL_SIZE)) {
gAtomTable.ops = nsnull;
return nsnull;
}
AtomTableKey key(aString, aLength);
return static_cast<AtomTableEntry*>
(PL_DHashTableOperate(&gAtomTable, &key, PL_DHASH_ADD));
}
static inline AtomTableEntry*
GetAtomHashEntry(const PRUnichar* aString, PRUint32 aLength)
{
NS_ASSERTION(NS_IsMainThread(), "wrong thread");
if (!gAtomTable.ops &&
!PL_DHashTableInit(&gAtomTable, &AtomTableOps, 0,
sizeof(AtomTableEntry), ATOM_HASHTABLE_INITIAL_SIZE)) {
gAtomTable.ops = nsnull;
return nsnull;
}
AtomTableKey key(aString, aLength);
return static_cast<AtomTableEntry*>
(PL_DHashTableOperate(&gAtomTable, &key, PL_DHASH_ADD));
}
class CheckStaticAtomSizes
{
CheckStaticAtomSizes() {
PR_STATIC_ASSERT((sizeof(nsFakeStringBuffer<1>().mRefCnt) ==
sizeof(nsStringBuffer().mRefCount)) &&
(sizeof(nsFakeStringBuffer<1>().mSize) ==
sizeof(nsStringBuffer().mStorageSize)) &&
(offsetof(nsFakeStringBuffer<1>, mRefCnt) ==
offsetof(nsStringBuffer, mRefCount)) &&
(offsetof(nsFakeStringBuffer<1>, mSize) ==
offsetof(nsStringBuffer, mStorageSize)) &&
(offsetof(nsFakeStringBuffer<1>, mStringData) ==
sizeof(nsStringBuffer)));
}
};
NS_COM nsresult
NS_RegisterStaticAtoms(const nsStaticAtom* aAtoms, PRUint32 aAtomCount)
{
// this does three things:
// 1) wraps each static atom in a wrapper, if necessary
// 2) initializes the address pointed to by each mBits slot
// 3) puts the atom into the static atom table as well
if (!gStaticAtomTable && !gStaticAtomTableSealed) {
gStaticAtomTable = new nsDataHashtable<nsStringHashKey, nsIAtom*>();
if (!gStaticAtomTable || !gStaticAtomTable->Init()) {
delete gStaticAtomTable;
gStaticAtomTable = nsnull;
return NS_ERROR_OUT_OF_MEMORY;
}
}
for (PRUint32 i=0; i<aAtomCount; i++) {
#ifdef NS_STATIC_ATOM_USE_WIDE_STRINGS
NS_ASSERTION(nsCRT::IsAscii((PRUnichar*)aAtoms[i].mStringBuffer->Data()),
"Static atoms must be ASCII!");
PRUint32 stringLen =
aAtoms[i].mStringBuffer->StorageSize() / sizeof(PRUnichar) - 1;
AtomTableEntry *he =
GetAtomHashEntry((PRUnichar*)aAtoms[i].mStringBuffer->Data(),
stringLen);
if (he->mAtom) {
// there already is an atom with this name in the table.. but we
// still have to update mBits
if (!he->mAtom->IsPermanent()) {
// since we wanted to create a static atom but there is
// already one there, we convert it to a non-refcounting
// permanent atom
PromoteToPermanent(he->mAtom);
}
*aAtoms[i].mAtom = he->mAtom;
}
else {
AtomImpl* atom = new PermanentAtomImpl(aAtoms[i].mStringBuffer,
stringLen);
he->mAtom = atom;
*aAtoms[i].mAtom = atom;
if (!gStaticAtomTableSealed) {
gStaticAtomTable->Put(nsAtomString(atom), atom);
}
}
#else // NS_STATIC_ATOM_USE_WIDE_STRINGS
NS_ASSERTION(nsCRT::IsAscii((char*)aAtoms[i].mStringBuffer->Data()),
"Static atoms must be ASCII!");
PRUint32 stringLen = aAtoms[i].mStringBuffer->StorageSize() - 1;
NS_ConvertASCIItoUTF16 str((char*)aAtoms[i].mStringBuffer->Data(),
stringLen);
nsIAtom* atom = NS_NewPermanentAtom(str);
*aAtoms[i].mAtom = atom;
if (!gStaticAtomTableSealed) {
gStaticAtomTable->Put(str, atom);
}
#endif
}
return NS_OK;
}
NS_COM nsIAtom*
NS_NewAtom(const char* aUTF8String)
{
return NS_NewAtom(nsDependentCString(aUTF8String));
}
NS_COM nsIAtom*
NS_NewAtom(const nsACString& aUTF8String)
{
AtomTableEntry *he = GetAtomHashEntry(aUTF8String.Data(),
aUTF8String.Length());
if (he->mAtom) {
nsIAtom* atom;
NS_ADDREF(atom = he->mAtom);
return atom;
}
// This results in an extra addref/release of the nsStringBuffer.
// Unfortunately there doesn't seem to be any APIs to avoid that.
nsString str;
CopyUTF8toUTF16(aUTF8String, str);
AtomImpl* atom = new AtomImpl(str);
he->mAtom = atom;
NS_ADDREF(atom);
return atom;
}
NS_COM nsIAtom*
NS_NewAtom(const PRUnichar* aUTF16String)
{
return NS_NewAtom(nsDependentString(aUTF16String));
}
NS_COM nsIAtom*
NS_NewAtom(const nsAString& aUTF16String)
{
AtomTableEntry *he = GetAtomHashEntry(aUTF16String.Data(),
aUTF16String.Length());
if (he->mAtom) {
nsIAtom* atom;
NS_ADDREF(atom = he->mAtom);
return atom;
}
AtomImpl* atom = new AtomImpl(aUTF16String);
he->mAtom = atom;
NS_ADDREF(atom);
return atom;
}
NS_COM nsIAtom*
NS_NewPermanentAtom(const nsAString& aUTF16String)
{
AtomTableEntry *he = GetAtomHashEntry(aUTF16String.Data(),
aUTF16String.Length());
AtomImpl* atom = he->mAtom;
if (atom) {
if (!atom->IsPermanent()) {
PromoteToPermanent(atom);
}
}
else {
atom = new PermanentAtomImpl(aUTF16String);
he->mAtom = atom;
}
// No need to addref since permanent atoms aren't refcounted anyway
return atom;
}
NS_COM nsrefcnt
NS_GetNumberOfAtoms(void)
{
return gAtomTable.entryCount;
}
NS_COM nsIAtom*
NS_GetStaticAtom(const nsAString& aUTF16String)
{
NS_PRECONDITION(gStaticAtomTable, "Static atom table not created yet.");
NS_PRECONDITION(gStaticAtomTableSealed, "Static atom table not sealed yet.");
nsIAtom* atom;
if (!gStaticAtomTable->Get(aUTF16String, &atom)) {
atom = nsnull;
}
return atom;
}
NS_COM void
NS_SealStaticAtomTable()
{
gStaticAtomTableSealed = PR_TRUE;
}
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