gecko-dev/xpcom/ds/nsAtomTable.cpp

769 строки
21 KiB
C++

/* -*- 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
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* decision by deleting the provisions above and replace them with the notice
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* the provisions above, a recipient may use your version of this file under
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*
* ***** END LICENSE BLOCK ***** */
#include "nsAtomTable.h"
#include "nsStaticAtom.h"
#include "nsString.h"
#include "nsReadableUtils.h"
#include "nsCRT.h"
#include "pldhash.h"
#include "prenv.h"
#define PL_ARENA_CONST_ALIGN_MASK 3
#include "plarena.h"
class nsStaticAtomWrapper;
/**
* 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;
// this is where we keep the nsStaticAtomWrapper objects
static PLArenaPool* gStaticAtomArena = 0;
class nsStaticAtomWrapper : public nsIAtom
{
public:
nsStaticAtomWrapper(const nsStaticAtom* aAtom) :
mStaticAtom(aAtom)
{
MOZ_COUNT_CTOR(nsStaticAtomWrapper);
}
~nsStaticAtomWrapper() { // no subclasses -> not virtual
// this is arena allocated and won't be called except in debug
// builds. If this function ever does anything non-debug, be sure
// to get rid of the ifdefs in AtomTableClearEntry!
MOZ_COUNT_DTOR(nsStaticAtomWrapper);
}
NS_IMETHOD QueryInterface(REFNSIID aIID,
void** aInstancePtr);
NS_IMETHOD_(nsrefcnt) AddRef(void);
NS_IMETHOD_(nsrefcnt) Release(void);
NS_DECL_NSIATOM
const nsStaticAtom* GetStaticAtom() {
return mStaticAtom;
}
private:
const nsStaticAtom* mStaticAtom;
};
// The |key| pointer in the various PLDHashTable callbacks we use is an
// AtomTableClearEntry*. These pointers can come from two places: either a
// (probably stack-allocated) string key being passed to PL_DHashTableOperate,
// or an actual entry in the atom table. PLDHashTable reseves the keyHash
// values 0 and 1 for internal use, which means that the *PLDHashTable code*
// will never pass an entry whose keyhash is 0 or 1 to our hooks. That means we
// can use those values to tell whether an AtomTableEntry is a string key
// created by a PLDHashTable code caller or an actual live AtomTableEntry used
// by our PLDHashTable.
//
// Evil? Yes, but kinda neat too :-)
//
// An AtomTableEntry is a UTF-8 string key if keyHash is 0, in that
// case mBits points to a UTF-8 encoded char *. If keyHash is 1 the
// AtomTableEntry is a UTF-16 encoded string key and mBits points to a
// UTF-16 encoded PRUnichar *.
//
// If keyHash is any other value (> 1), the AtomTableEntry is an
// actual live entry in the table, and then mBits & ~0x1 in the
// AtomTableEntry points to an AtomImpl or a nsStaticAtomWrapper,
// indicated by the first bit of PtrBits.
typedef PRUword PtrBits;
struct AtomTableEntry : public PLDHashEntryHdr {
// If keyHash > 1, mBits & 0x1 means (mBits & ~0x1) points to an
// nsStaticAtomWrapper else it points to an nsAtomImpl
PtrBits mBits;
inline AtomTableEntry(const char *aString)
: mBits(PtrBits(aString))
{
keyHash = 0;
}
inline AtomTableEntry(const PRUnichar *aString)
: mBits(PtrBits(aString))
{
keyHash = 1;
}
inline PRBool IsStaticAtom() const {
NS_ASSERTION(keyHash > 1,
"IsStaticAtom() called on non-atom AtomTableEntry!");
return (mBits & 0x1) != 0;
}
inline PRBool IsUTF8String() const {
return keyHash == 0;
}
inline PRBool IsUTF16String() const {
return keyHash == 1;
}
inline void SetAtomImpl(AtomImpl* aAtom) {
NS_ASSERTION(keyHash > 1,
"SetAtomImpl() called on non-atom AtomTableEntry!");
NS_ASSERTION(aAtom, "Setting null atom");
mBits = PtrBits(aAtom);
}
inline void SetStaticAtomWrapper(nsStaticAtomWrapper* aAtom) {
NS_ASSERTION(keyHash > 1,
"SetStaticAtomWrapper() called on non-atom AtomTableEntry!");
NS_ASSERTION(aAtom, "Setting null atom");
NS_ASSERTION((PtrBits(aAtom) & ~0x1) == PtrBits(aAtom),
"Pointers must align or this is broken");
mBits = PtrBits(aAtom) | 0x1;
}
inline void ClearAtom() {
mBits = nsnull;
}
inline PRBool HasValue() const {
NS_ASSERTION(keyHash > 1,
"HasValue() called on non-atom AtomTableEntry!");
return (mBits & ~0x1) != 0;
}
// these accessors assume that you already know the type
inline AtomImpl *GetAtomImpl() const {
NS_ASSERTION(keyHash > 1,
"GetAtomImpl() called on non-atom AtomTableEntry!");
NS_ASSERTION(!IsStaticAtom(), "This is a static atom, not an AtomImpl");
return (AtomImpl*) (mBits & ~0x1);
}
inline nsStaticAtomWrapper *GetStaticAtomWrapper() const {
NS_ASSERTION(keyHash > 1,
"GetStaticAtomWrapper() called on non-atom AtomTableEntry!");
NS_ASSERTION(IsStaticAtom(), "This is an AtomImpl, not a static atom");
return (nsStaticAtomWrapper*) (mBits & ~0x1);
}
inline const nsStaticAtom* GetStaticAtom() const {
NS_ASSERTION(keyHash > 1,
"GetStaticAtom() called on non-atom AtomTableEntry!");
return GetStaticAtomWrapper()->GetStaticAtom();
}
// type-agnostic accessors
// get the string buffer
inline const char* getAtomString() const {
NS_ASSERTION(keyHash > 1,
"getAtomString() called on non-atom AtomTableEntry!");
return IsStaticAtom() ? GetStaticAtom()->mString : GetAtomImpl()->mString;
}
// get the string buffer
inline const char* getUTF8String() const {
NS_ASSERTION(keyHash == 0,
"getUTF8String() called on non-UTF8 AtomTableEntry!");
return (char *)mBits;
}
// get the string buffer
inline const PRUnichar* getUTF16String() const {
NS_ASSERTION(keyHash == 1,
"getUTF16String() called on non-UTF16 AtomTableEntry!");
return (PRUnichar *)mBits;
}
// get an addreffed nsIAtom - not using already_AddRef'ed atom
// because the callers are not (and should not be) using nsCOMPtr
inline nsIAtom* GetAtom() const {
NS_ASSERTION(keyHash > 1,
"GetAtom() called on non-atom AtomTableEntry!");
nsIAtom* result;
if (IsStaticAtom())
result = GetStaticAtomWrapper();
else {
result = GetAtomImpl();
NS_ADDREF(result);
}
return result;
}
};
PR_STATIC_CALLBACK(const void *)
AtomTableGetKey(PLDHashTable *table, PLDHashEntryHdr *entry)
{
AtomTableEntry *he = NS_STATIC_CAST(AtomTableEntry*, entry);
NS_ASSERTION(he->HasValue(), "Empty atom. how did that happen?");
return he;
}
PR_STATIC_CALLBACK(PLDHashNumber)
AtomTableGetHash(PLDHashTable *table, const void *key)
{
const AtomTableEntry *e = NS_STATIC_CAST(const AtomTableEntry*, key);
if (e->IsUTF16String()) {
return nsCRT::HashCodeAsUTF8(e->getUTF16String());
}
NS_ASSERTION(e->IsUTF8String(),
"AtomTableGetHash() called on non-string-key AtomTableEntry!");
return nsCRT::HashCode(e->getUTF8String());
}
PR_STATIC_CALLBACK(PRBool)
AtomTableMatchKey(PLDHashTable *table, const PLDHashEntryHdr *entry,
const void *key)
{
const AtomTableEntry *he = NS_STATIC_CAST(const AtomTableEntry*, entry);
const AtomTableEntry *strKey = NS_STATIC_CAST(const AtomTableEntry*, key);
const char *atomString = he->getAtomString();
if (strKey->IsUTF16String()) {
return
CompareUTF8toUTF16(nsDependentCString(atomString),
nsDependentString(strKey->getUTF16String())) == 0;
}
if (strKey->IsUTF8String()) {
return strcmp(atomString, strKey->getUTF8String()) == 0;
}
return strcmp(atomString, strKey->getAtomString()) == 0;
}
PR_STATIC_CALLBACK(void)
AtomTableClearEntry(PLDHashTable *table, PLDHashEntryHdr *entry)
{
AtomTableEntry *he = NS_STATIC_CAST(AtomTableEntry*, entry);
if (!he->IsStaticAtom()) {
AtomImpl *atom = he->GetAtomImpl();
// 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.
if (atom->IsPermanent()) {
he->keyHash = 0;
delete NS_STATIC_CAST(PermanentAtomImpl*, atom);
}
}
else {
he->GetStaticAtomWrapper()->~nsStaticAtomWrapper();
}
he->ClearAtom();
}
static const PLDHashTableOps AtomTableOps = {
PL_DHashAllocTable,
PL_DHashFreeTable,
AtomTableGetKey,
AtomTableGetHash,
AtomTableMatchKey,
PL_DHashMoveEntryStub,
AtomTableClearEntry,
PL_DHashFinalizeStub,
NULL
};
#ifdef DEBUG
PR_STATIC_CALLBACK(PLDHashOperator)
DumpAtomLeaks(PLDHashTable *table, PLDHashEntryHdr *he,
PRUint32 index, void *arg)
{
AtomTableEntry *entry = NS_STATIC_CAST(AtomTableEntry*, he);
if (entry->IsStaticAtom())
return PL_DHASH_NEXT;
AtomImpl* atom = entry->GetAtomImpl();
if (!atom->IsPermanent()) {
++*NS_STATIC_CAST(PRUint32*, arg);
const char *str;
atom->GetUTF8String(&str);
fputs(str, 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()
{
if (gAtomTable.ops) {
#ifdef DEBUG
if (PR_GetEnv("MOZ_DUMP_ATOM_LEAKS")) {
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;
if (gStaticAtomArena) {
PL_FinishArenaPool(gStaticAtomArena);
delete gStaticAtomArena;
gStaticAtomArena = nsnull;
}
}
}
AtomImpl::AtomImpl()
{
}
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 (!IsPermanent()) {
AtomTableEntry key(mString);
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");
}
}
}
NS_IMPL_THREADSAFE_ISUPPORTS1(AtomImpl, nsIAtom)
NS_IMETHODIMP_(nsrefcnt) PermanentAtomImpl::AddRef()
{
return 2;
}
NS_IMETHODIMP_(nsrefcnt) PermanentAtomImpl::Release()
{
return 1;
}
/* virtual */ PRBool
AtomImpl::IsPermanent()
{
return PR_FALSE;
}
/* virtual */ PRBool
PermanentAtomImpl::IsPermanent()
{
return PR_TRUE;
}
void* AtomImpl::operator new ( size_t size, const nsACString& aString ) CPP_THROW_NEW
{
/*
Note: since the |size| will initially also include the |PRUnichar| member
|mString|, our size calculation will give us one character too many.
We use that extra character for a zero-terminator.
Note: this construction is not guaranteed to be possible by the C++
compiler. A more reliable scheme is used by |nsShared[C]String|s, see
http://lxr.mozilla.org/seamonkey/source/xpcom/ds/nsSharedString.h#174
*/
size += aString.Length() * sizeof(char);
AtomImpl* ii = NS_STATIC_CAST(AtomImpl*, ::operator new(size));
char* toBegin = &ii->mString[0];
nsACString::const_iterator fromBegin, fromEnd;
*copy_string(aString.BeginReading(fromBegin), aString.EndReading(fromEnd), toBegin) = '\0';
return ii;
}
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::ToString(nsAString& aBuf)
{
CopyUTF8toUTF16(nsDependentCString(mString), aBuf);
return NS_OK;
}
NS_IMETHODIMP
AtomImpl::ToUTF8String(nsACString& aBuf)
{
aBuf.Assign(mString);
return NS_OK;
}
NS_IMETHODIMP
AtomImpl::GetUTF8String(const char **aResult)
{
NS_PRECONDITION(aResult, "null out param");
*aResult = mString;
return NS_OK;
}
NS_IMETHODIMP
AtomImpl::EqualsUTF8(const nsACString& aString, PRBool* aResult)
{
*aResult = aString.Equals(mString);
return NS_OK;
}
NS_IMETHODIMP
AtomImpl::Equals(const nsAString& aString, PRBool* aResult)
{
*aResult = CompareUTF8toUTF16(nsDependentCString(mString),
PromiseFlatString(aString)) == 0;
return NS_OK;
}
//----------------------------------------------------------------------
// wrapper class for the nsStaticAtom struct
NS_IMETHODIMP_(nsrefcnt)
nsStaticAtomWrapper::AddRef()
{
return 2;
}
NS_IMETHODIMP_(nsrefcnt)
nsStaticAtomWrapper::Release()
{
return 1;
}
NS_IMPL_QUERY_INTERFACE1(nsStaticAtomWrapper, nsIAtom)
NS_IMETHODIMP
nsStaticAtomWrapper::GetUTF8String(const char** aResult)
{
*aResult = mStaticAtom->mString;
return NS_OK;
}
NS_IMETHODIMP
nsStaticAtomWrapper::ToString(nsAString& aBuf)
{
// static should always be always ASCII, to allow tools like gperf
// to generate the tables, and to avoid unnecessary conversion
NS_ASSERTION(nsCRT::IsAscii(mStaticAtom->mString),
"Data loss - atom should be ASCII");
CopyASCIItoUCS2(nsDependentCString(mStaticAtom->mString), aBuf);
return NS_OK;
}
NS_IMETHODIMP
nsStaticAtomWrapper::ToUTF8String(nsACString& aBuf)
{
aBuf.Assign(mStaticAtom->mString);
return NS_OK;
}
NS_IMETHODIMP
nsStaticAtomWrapper::EqualsUTF8(const nsACString& aString, PRBool* aResult)
{
*aResult = aString.Equals(mStaticAtom->mString);
return NS_OK;
}
NS_IMETHODIMP
nsStaticAtomWrapper::Equals(const nsAString& aString, PRBool* aResult)
{
*aResult = CompareUTF8toUTF16(nsDependentCString(mStaticAtom->mString),
PromiseFlatString(aString)) == 0;
return NS_OK;
}
//----------------------------------------------------------------------
static nsStaticAtomWrapper*
WrapStaticAtom(const nsStaticAtom* aAtom)
{
if (!gStaticAtomArena) {
gStaticAtomArena = new PLArenaPool;
if (!gStaticAtomArena)
return nsnull;
PL_INIT_ARENA_POOL(gStaticAtomArena, "nsStaticAtomArena", 4096);
}
void* mem;
PL_ARENA_ALLOCATE(mem, gStaticAtomArena, sizeof(nsStaticAtom));
nsStaticAtomWrapper* wrapper =
new (mem) nsStaticAtomWrapper(aAtom);
return wrapper;
}
static inline AtomTableEntry*
GetAtomHashEntry(const char* aString)
{
if (!gAtomTable.ops &&
!PL_DHashTableInit(&gAtomTable, &AtomTableOps, 0,
sizeof(AtomTableEntry), 2048)) {
gAtomTable.ops = nsnull;
return nsnull;
}
AtomTableEntry key(aString);
return NS_STATIC_CAST(AtomTableEntry*,
PL_DHashTableOperate(&gAtomTable, &key, PL_DHASH_ADD));
}
static inline AtomTableEntry*
GetAtomHashEntry(const PRUnichar* aString)
{
if (!gAtomTable.ops &&
!PL_DHashTableInit(&gAtomTable, &AtomTableOps, 0,
sizeof(AtomTableEntry), 2048)) {
gAtomTable.ops = nsnull;
return nsnull;
}
AtomTableEntry key(aString);
return NS_STATIC_CAST(AtomTableEntry*,
PL_DHashTableOperate(&gAtomTable, &key, PL_DHASH_ADD));
}
NS_COM nsresult
NS_RegisterStaticAtoms(const nsStaticAtom* aAtoms, PRUint32 aAtomCount)
{
// this does two things:
// 1) wraps each static atom in a wrapper, if necessary
// 2) initializes the address pointed to by each mBits slot
for (PRUint32 i=0; i<aAtomCount; i++) {
NS_ASSERTION(nsCRT::IsAscii(aAtoms[i].mString),
"Static atoms must be ASCII!");
AtomTableEntry *he =
GetAtomHashEntry(aAtoms[i].mString);
if (he->HasValue() && aAtoms[i].mAtom) {
// there already is an atom with this name in the table.. but we
// still have to update mBits
if (!he->IsStaticAtom() && !he->GetAtomImpl()->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->GetAtomImpl());
}
// and now, if the consumer wants to remember this value in a
// slot, we do so
if (aAtoms[i].mAtom)
*aAtoms[i].mAtom = he->GetAtom();
}
else {
nsStaticAtomWrapper* atom = WrapStaticAtom(&aAtoms[i]);
NS_ASSERTION(atom, "Failed to wrap static atom");
// but even if atom is null, no real difference in code..
he->SetStaticAtomWrapper(atom);
if (aAtoms[i].mAtom)
*aAtoms[i].mAtom = atom;
}
}
return NS_OK;
}
NS_COM nsIAtom*
NS_NewAtom(const char* aUTF8String)
{
AtomTableEntry *he = GetAtomHashEntry(aUTF8String);
if (!he) {
return nsnull;
}
NS_ASSERTION(!he->IsUTF8String() && !he->IsUTF16String(),
"Atom hash entry is string? Should be atom!");
if (he->HasValue())
return he->GetAtom();
// MSVC.NET doesn't like passing a temporary nsDependentCString() to
// operator new, so declare one as a local instead.
nsDependentCString str(aUTF8String);
AtomImpl* atom = new (str) AtomImpl();
he->SetAtomImpl(atom);
if (!atom) {
PL_DHashTableRawRemove(&gAtomTable, he);
return nsnull;
}
NS_ADDREF(atom);
return atom;
}
NS_COM nsIAtom*
NS_NewAtom(const nsACString& aUTF8String)
{
return NS_NewAtom(PromiseFlatCString(aUTF8String).get());
}
NS_COM nsIAtom*
NS_NewAtom(const PRUnichar* aUTF16String)
{
AtomTableEntry *he = GetAtomHashEntry(aUTF16String);
if (he->HasValue())
return he->GetAtom();
// MSVC.NET doesn't like passing a temporary NS_ConvertUTF16toUTF8() to
// operator new, so declare one as a local instead.
NS_ConvertUTF16toUTF8 str(aUTF16String);
AtomImpl* atom = new (str) AtomImpl();
he->SetAtomImpl(atom);
if (!atom) {
PL_DHashTableRawRemove(&gAtomTable, he);
return nsnull;
}
NS_ADDREF(atom);
return atom;
}
NS_COM nsIAtom*
NS_NewAtom(const nsAString& aUTF16String)
{
return NS_NewAtom(PromiseFlatString(aUTF16String).get());
}
NS_COM nsIAtom*
NS_NewPermanentAtom(const char* aUTF8String)
{
return NS_NewPermanentAtom(nsDependentCString(aUTF8String));
}
NS_COM nsIAtom*
NS_NewPermanentAtom(const nsACString& aUTF8String)
{
AtomTableEntry *he = GetAtomHashEntry(PromiseFlatCString(aUTF8String).get());
if (he->HasValue() && he->IsStaticAtom())
return he->GetStaticAtomWrapper();
// either there is no atom and we'll create an AtomImpl,
// or there is an existing AtomImpl
AtomImpl* atom = he->GetAtomImpl();
if (atom) {
// ensure that it's permanent
if (!atom->IsPermanent()) {
PromoteToPermanent(atom);
}
} else {
// otherwise, make a new atom
atom = new (aUTF8String) PermanentAtomImpl();
he->SetAtomImpl(atom);
if ( !atom ) {
PL_DHashTableRawRemove(&gAtomTable, he);
return nsnull;
}
}
NS_ADDREF(atom);
return atom;
}
NS_COM nsIAtom*
NS_NewPermanentAtom(const nsAString& aUTF16String)
{
return NS_NewPermanentAtom(NS_ConvertUTF16toUTF8(aUTF16String));
}
NS_COM nsIAtom*
NS_NewPermanentAtom(const PRUnichar* aUTF16String)
{
return NS_NewPermanentAtom(NS_ConvertUTF16toUTF8(aUTF16String));
}
NS_COM nsrefcnt
NS_GetNumberOfAtoms(void)
{
return gAtomTable.entryCount;
}