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Fix nsSharableString::SetLength to correctly handle having a shared buffer. Override GetWritableFragment on nsSharableString (perhaps temporarily) to allow use of writing iterators on nsSharableString. b=114438 r=jag sr=jst

This commit is contained in:
dbaron%fas.harvard.edu 2001-12-11 03:33:09 +00:00
Родитель 3927848470
Коммит 487c581ac0
6 изменённых файлов: 120 добавлений и 42 удалений
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9
string/public/nsBufferHandle.h
Просмотреть файл

@ -189,7 +189,7 @@ class nsSharedBufferHandle
protected:
enum
{
kIsShared = 0x01000000, // one reason _not_ to set this is for a stack based handle that wants to express `NULL'-ness et al
kIsImmutable = 0x01000000, // if this is set, the buffer cannot be modified even if its refcount is 1
kIsSingleAllocationWithBuffer = 0x02000000, // handle and buffer are one piece, no separate deallocation is possible for the buffer
kIsUserAllocator = 0x04000000, // can't |delete|, call a hook instead
@ -204,9 +204,9 @@ class nsSharedBufferHandle
public:
nsSharedBufferHandle( CharT* aDataStart, CharT* aDataEnd, size_type aStorageLength, PRBool isSingleAllocation )
: nsBufferHandle<CharT>(aDataStart, aDataEnd),
mFlags(0),
mStorageLength(aStorageLength)
{
mFlags = kIsShared;
if ( isSingleAllocation )
mFlags |= kIsSingleAllocationWithBuffer;
}
@ -236,9 +236,10 @@ class nsSharedBufferHandle
}
PRBool
IsShared() const
IsMutable() const
{
return get_refcount() > 1;
// (get_refcount() == 1) && !(GetImplementationFlags() & kIsImmutable)
return (mFlags & (kRefCountMask | kIsImmutable) == 1);
}
void StorageLength( size_type aNewStorageLength )

6
string/public/nsSharableString.h
Просмотреть файл

@ -94,6 +94,9 @@ class NS_COM nsSharableString
protected:
virtual void do_AssignFromReadable( const abstract_string_type& aReadable );
virtual const shared_buffer_handle_type* GetSharedBufferHandle() const;
// protected: // can't hide these (yet), since I call them from forwarding routines in |nsPromiseFlatString|
public:
virtual char_type* GetWritableFragment( fragment_type&, nsFragmentRequest, PRUint32 );
protected:
static shared_buffer_handle_type* GetSharedEmptyBufferHandle();
@ -153,6 +156,9 @@ class NS_COM nsSharableCString
protected:
virtual void do_AssignFromReadable( const abstract_string_type& aReadable );
virtual const shared_buffer_handle_type* GetSharedBufferHandle() const;
// protected: // can't hide these (yet), since I call them from forwarding routines in |nsPromiseFlatString|
public:
virtual char_type* GetWritableFragment( fragment_type&, nsFragmentRequest, PRUint32 );
protected:
static shared_buffer_handle_type* GetSharedEmptyBufferHandle();

66
string/src/nsSharableString.cpp
Просмотреть файл

@ -56,11 +56,11 @@ nsSharableString::SetCapacity( size_type aNewCapacity )
// therefore *unconditionally* truncate the current length of
// the string to the requested capacity.
if ( mBuffer->IsShared() )
if ( !mBuffer->IsMutable() )
{
if ( aNewCapacity > Length() )
if ( aNewCapacity > mBuffer->DataLength() )
mBuffer = NS_AllocateContiguousHandleWithData(mBuffer.get(),
*this, PRUint32(aNewCapacity - Length() + 1));
*this, PRUint32(aNewCapacity - mBuffer->DataLength() + 1));
else
mBuffer = NS_AllocateContiguousHandleWithData(mBuffer.get(),
Substring(*this, 0, aNewCapacity), PRUint32(1));
@ -78,10 +78,10 @@ nsSharableString::SetCapacity( size_type aNewCapacity )
aNewCapacity = doubledCapacity;
// XXX We should be able to use |realloc| under certain
// conditions (contiguous buffer handle, kIsShared
// (,etc.)?)
// conditions (contiguous buffer handle, not
// kIsImmutable (,etc.)?)
mBuffer = NS_AllocateContiguousHandleWithData(mBuffer.get(),
*this, PRUint32(aNewCapacity - Length() + 1));
*this, PRUint32(aNewCapacity - mBuffer->DataLength() + 1));
}
else if ( aNewCapacity < mBuffer->DataLength() )
{
@ -100,7 +100,7 @@ nsSharableString::SetCapacity( size_type aNewCapacity )
void
nsSharableString::SetLength( size_type aNewLength )
{
if ( aNewLength > mBuffer->DataLength() )
if ( !mBuffer->IsMutable() || aNewLength > mBuffer->DataLength() )
{
SetCapacity(aNewLength);
mBuffer->DataEnd( mBuffer->DataStart() + aNewLength );
@ -128,7 +128,7 @@ nsSharableString::do_AssignFromReadable( const abstract_string_type& aReadable )
{
// null-check |mBuffer.get()| here only for the constructor
// taking |const abstract_string_type&|
if ( mBuffer.get() && !mBuffer->IsShared() &&
if ( mBuffer.get() && mBuffer->IsMutable() &&
mBuffer->StorageLength() > aReadable.Length() &&
!aReadable.IsDependentOn(*this) )
{
@ -175,6 +175,22 @@ nsSharableString::GetSharedEmptyBufferHandle()
return sBufferHandle;
}
// The need to override GetWritableFragment may be temporary, depending
// on the protocol we choose for callers who want to mutate strings
// using iterators. See
// <URL: http://bugzilla.mozilla.org/show_bug.cgi?id=114140 >
nsSharableString::char_type*
nsSharableString::GetWritableFragment( fragment_type& aFragment, nsFragmentRequest aRequest, PRUint32 aOffset )
{
// This makes writing iterators safe to use, but it imposes a
// double-malloc performance penalty on users who intend to modify
// the length of the string but call |BeginWriting| before they call
// |SetLength|.
if ( mBuffer->IsMutable() )
SetCapacity( mBuffer->DataLength() );
return nsAFlatString::GetWritableFragment( aFragment, aRequest, aOffset );
}
void
nsSharableCString::SetCapacity( size_type aNewCapacity )
@ -205,11 +221,11 @@ nsSharableCString::SetCapacity( size_type aNewCapacity )
// therefore *unconditionally* truncate the current length of
// the string to the requested capacity.
if ( mBuffer->IsShared() )
if ( !mBuffer->IsMutable() )
{
if ( aNewCapacity > Length() )
if ( aNewCapacity > mBuffer->DataLength() )
mBuffer = NS_AllocateContiguousHandleWithData(mBuffer.get(),
*this, PRUint32(aNewCapacity - Length() + 1));
*this, PRUint32(aNewCapacity - mBuffer->DataLength() + 1));
else
mBuffer = NS_AllocateContiguousHandleWithData(mBuffer.get(),
Substring(*this, 0, aNewCapacity), PRUint32(1));
@ -227,10 +243,10 @@ nsSharableCString::SetCapacity( size_type aNewCapacity )
aNewCapacity = doubledCapacity;
// XXX We should be able to use |realloc| under certain
// conditions (contiguous buffer handle, kIsShared
// (,etc.)?)
// conditions (contiguous buffer handle, not
// kIsImmutable (,etc.)?)
mBuffer = NS_AllocateContiguousHandleWithData(mBuffer.get(),
*this, PRUint32(aNewCapacity - Length() + 1));
*this, PRUint32(aNewCapacity - mBuffer->DataLength() + 1));
}
else if ( aNewCapacity < mBuffer->DataLength() )
{
@ -249,7 +265,7 @@ nsSharableCString::SetCapacity( size_type aNewCapacity )
void
nsSharableCString::SetLength( size_type aNewLength )
{
if ( aNewLength > mBuffer->DataLength() )
if ( !mBuffer->IsMutable() || aNewLength > mBuffer->DataLength() )
{
SetCapacity(aNewLength);
mBuffer->DataEnd( mBuffer->DataStart() + aNewLength );
@ -261,7 +277,7 @@ nsSharableCString::SetLength( size_type aNewLength )
// This is needed for |Truncate| callers and also for some callers
// (such as nsACString::do_AppendFromReadable) that are manipulating
// the internals of the string. It also makes sense to do this
// since this class implements |nsAFlatString|, so the buffer must
// since this class implements |nsAFlatCString|, so the buffer must
// always be null-terminated at its length. Callers using writing
// iterators can't be expected to null-terminate themselves since
// they don't know if they're dealing with a string that has a
@ -277,7 +293,7 @@ nsSharableCString::do_AssignFromReadable( const abstract_string_type& aReadable
{
// null-check |mBuffer.get()| here only for the constructor
// taking |const abstract_string_type&|
if ( mBuffer.get() && !mBuffer->IsShared() &&
if ( mBuffer.get() && mBuffer->IsMutable() &&
mBuffer->StorageLength() > aReadable.Length() &&
!aReadable.IsDependentOn(*this) )
{
@ -324,3 +340,19 @@ nsSharableCString::GetSharedEmptyBufferHandle()
return sBufferHandle;
}
// The need to override GetWritableFragment may be temporary, depending
// on the protocol we choose for callers who want to mutate strings
// using iterators. See
// <URL: http://bugzilla.mozilla.org/show_bug.cgi?id=114140 >
nsSharableCString::char_type*
nsSharableCString::GetWritableFragment( fragment_type& aFragment, nsFragmentRequest aRequest, PRUint32 aOffset )
{
// This makes writing iterators safe to use, but it imposes a
// double-malloc performance penalty on users who intend to modify
// the length of the string but call |BeginWriting| before they call
// |SetLength|.
if ( mBuffer->IsMutable() )
SetCapacity( mBuffer->DataLength() );
return nsAFlatCString::GetWritableFragment( aFragment, aRequest, aOffset );
}

9
xpcom/string/public/nsBufferHandle.h
Просмотреть файл

@ -189,7 +189,7 @@ class nsSharedBufferHandle
protected:
enum
{
kIsShared = 0x01000000, // one reason _not_ to set this is for a stack based handle that wants to express `NULL'-ness et al
kIsImmutable = 0x01000000, // if this is set, the buffer cannot be modified even if its refcount is 1
kIsSingleAllocationWithBuffer = 0x02000000, // handle and buffer are one piece, no separate deallocation is possible for the buffer
kIsUserAllocator = 0x04000000, // can't |delete|, call a hook instead
@ -204,9 +204,9 @@ class nsSharedBufferHandle
public:
nsSharedBufferHandle( CharT* aDataStart, CharT* aDataEnd, size_type aStorageLength, PRBool isSingleAllocation )
: nsBufferHandle<CharT>(aDataStart, aDataEnd),
mFlags(0),
mStorageLength(aStorageLength)
{
mFlags = kIsShared;
if ( isSingleAllocation )
mFlags |= kIsSingleAllocationWithBuffer;
}
@ -236,9 +236,10 @@ class nsSharedBufferHandle
}
PRBool
IsShared() const
IsMutable() const
{
return get_refcount() > 1;
// (get_refcount() == 1) && !(GetImplementationFlags() & kIsImmutable)
return (mFlags & (kRefCountMask | kIsImmutable) == 1);
}
void StorageLength( size_type aNewStorageLength )

6
xpcom/string/public/nsSharableString.h
Просмотреть файл

@ -94,6 +94,9 @@ class NS_COM nsSharableString
protected:
virtual void do_AssignFromReadable( const abstract_string_type& aReadable );
virtual const shared_buffer_handle_type* GetSharedBufferHandle() const;
// protected: // can't hide these (yet), since I call them from forwarding routines in |nsPromiseFlatString|
public:
virtual char_type* GetWritableFragment( fragment_type&, nsFragmentRequest, PRUint32 );
protected:
static shared_buffer_handle_type* GetSharedEmptyBufferHandle();
@ -153,6 +156,9 @@ class NS_COM nsSharableCString
protected:
virtual void do_AssignFromReadable( const abstract_string_type& aReadable );
virtual const shared_buffer_handle_type* GetSharedBufferHandle() const;
// protected: // can't hide these (yet), since I call them from forwarding routines in |nsPromiseFlatString|
public:
virtual char_type* GetWritableFragment( fragment_type&, nsFragmentRequest, PRUint32 );
protected:
static shared_buffer_handle_type* GetSharedEmptyBufferHandle();

66
xpcom/string/src/nsSharableString.cpp
Просмотреть файл

@ -56,11 +56,11 @@ nsSharableString::SetCapacity( size_type aNewCapacity )
// therefore *unconditionally* truncate the current length of
// the string to the requested capacity.
if ( mBuffer->IsShared() )
if ( !mBuffer->IsMutable() )
{
if ( aNewCapacity > Length() )
if ( aNewCapacity > mBuffer->DataLength() )
mBuffer = NS_AllocateContiguousHandleWithData(mBuffer.get(),
*this, PRUint32(aNewCapacity - Length() + 1));
*this, PRUint32(aNewCapacity - mBuffer->DataLength() + 1));
else
mBuffer = NS_AllocateContiguousHandleWithData(mBuffer.get(),
Substring(*this, 0, aNewCapacity), PRUint32(1));
@ -78,10 +78,10 @@ nsSharableString::SetCapacity( size_type aNewCapacity )
aNewCapacity = doubledCapacity;
// XXX We should be able to use |realloc| under certain
// conditions (contiguous buffer handle, kIsShared
// (,etc.)?)
// conditions (contiguous buffer handle, not
// kIsImmutable (,etc.)?)
mBuffer = NS_AllocateContiguousHandleWithData(mBuffer.get(),
*this, PRUint32(aNewCapacity - Length() + 1));
*this, PRUint32(aNewCapacity - mBuffer->DataLength() + 1));
}
else if ( aNewCapacity < mBuffer->DataLength() )
{
@ -100,7 +100,7 @@ nsSharableString::SetCapacity( size_type aNewCapacity )
void
nsSharableString::SetLength( size_type aNewLength )
{
if ( aNewLength > mBuffer->DataLength() )
if ( !mBuffer->IsMutable() || aNewLength > mBuffer->DataLength() )
{
SetCapacity(aNewLength);
mBuffer->DataEnd( mBuffer->DataStart() + aNewLength );
@ -128,7 +128,7 @@ nsSharableString::do_AssignFromReadable( const abstract_string_type& aReadable )
{
// null-check |mBuffer.get()| here only for the constructor
// taking |const abstract_string_type&|
if ( mBuffer.get() && !mBuffer->IsShared() &&
if ( mBuffer.get() && mBuffer->IsMutable() &&
mBuffer->StorageLength() > aReadable.Length() &&
!aReadable.IsDependentOn(*this) )
{
@ -175,6 +175,22 @@ nsSharableString::GetSharedEmptyBufferHandle()
return sBufferHandle;
}
// The need to override GetWritableFragment may be temporary, depending
// on the protocol we choose for callers who want to mutate strings
// using iterators. See
// <URL: http://bugzilla.mozilla.org/show_bug.cgi?id=114140 >
nsSharableString::char_type*
nsSharableString::GetWritableFragment( fragment_type& aFragment, nsFragmentRequest aRequest, PRUint32 aOffset )
{
// This makes writing iterators safe to use, but it imposes a
// double-malloc performance penalty on users who intend to modify
// the length of the string but call |BeginWriting| before they call
// |SetLength|.
if ( mBuffer->IsMutable() )
SetCapacity( mBuffer->DataLength() );
return nsAFlatString::GetWritableFragment( aFragment, aRequest, aOffset );
}
void
nsSharableCString::SetCapacity( size_type aNewCapacity )
@ -205,11 +221,11 @@ nsSharableCString::SetCapacity( size_type aNewCapacity )
// therefore *unconditionally* truncate the current length of
// the string to the requested capacity.
if ( mBuffer->IsShared() )
if ( !mBuffer->IsMutable() )
{
if ( aNewCapacity > Length() )
if ( aNewCapacity > mBuffer->DataLength() )
mBuffer = NS_AllocateContiguousHandleWithData(mBuffer.get(),
*this, PRUint32(aNewCapacity - Length() + 1));
*this, PRUint32(aNewCapacity - mBuffer->DataLength() + 1));
else
mBuffer = NS_AllocateContiguousHandleWithData(mBuffer.get(),
Substring(*this, 0, aNewCapacity), PRUint32(1));
@ -227,10 +243,10 @@ nsSharableCString::SetCapacity( size_type aNewCapacity )
aNewCapacity = doubledCapacity;
// XXX We should be able to use |realloc| under certain
// conditions (contiguous buffer handle, kIsShared
// (,etc.)?)
// conditions (contiguous buffer handle, not
// kIsImmutable (,etc.)?)
mBuffer = NS_AllocateContiguousHandleWithData(mBuffer.get(),
*this, PRUint32(aNewCapacity - Length() + 1));
*this, PRUint32(aNewCapacity - mBuffer->DataLength() + 1));
}
else if ( aNewCapacity < mBuffer->DataLength() )
{
@ -249,7 +265,7 @@ nsSharableCString::SetCapacity( size_type aNewCapacity )
void
nsSharableCString::SetLength( size_type aNewLength )
{
if ( aNewLength > mBuffer->DataLength() )
if ( !mBuffer->IsMutable() || aNewLength > mBuffer->DataLength() )
{
SetCapacity(aNewLength);
mBuffer->DataEnd( mBuffer->DataStart() + aNewLength );
@ -261,7 +277,7 @@ nsSharableCString::SetLength( size_type aNewLength )
// This is needed for |Truncate| callers and also for some callers
// (such as nsACString::do_AppendFromReadable) that are manipulating
// the internals of the string. It also makes sense to do this
// since this class implements |nsAFlatString|, so the buffer must
// since this class implements |nsAFlatCString|, so the buffer must
// always be null-terminated at its length. Callers using writing
// iterators can't be expected to null-terminate themselves since
// they don't know if they're dealing with a string that has a
@ -277,7 +293,7 @@ nsSharableCString::do_AssignFromReadable( const abstract_string_type& aReadable
{
// null-check |mBuffer.get()| here only for the constructor
// taking |const abstract_string_type&|
if ( mBuffer.get() && !mBuffer->IsShared() &&
if ( mBuffer.get() && mBuffer->IsMutable() &&
mBuffer->StorageLength() > aReadable.Length() &&
!aReadable.IsDependentOn(*this) )
{
@ -324,3 +340,19 @@ nsSharableCString::GetSharedEmptyBufferHandle()
return sBufferHandle;
}
// The need to override GetWritableFragment may be temporary, depending
// on the protocol we choose for callers who want to mutate strings
// using iterators. See
// <URL: http://bugzilla.mozilla.org/show_bug.cgi?id=114140 >
nsSharableCString::char_type*
nsSharableCString::GetWritableFragment( fragment_type& aFragment, nsFragmentRequest aRequest, PRUint32 aOffset )
{
// This makes writing iterators safe to use, but it imposes a
// double-malloc performance penalty on users who intend to modify
// the length of the string but call |BeginWriting| before they call
// |SetLength|.
if ( mBuffer->IsMutable() )
SetCapacity( mBuffer->DataLength() );
return nsAFlatCString::GetWritableFragment( aFragment, aRequest, aOffset );
}