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Fixing bug 413569. Make XPCWrappedNative::CallMethod() initialize the nsAutoString buffer used for [out] string param handling only when needed. r+sr=jonas@sicking.cc

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This commit is contained in:
jst@mozilla.org 2008-01-23 17:17:13 -08:00
parent 1933182dfd
commit 33bb88f086
1 changed files with 27 additions and 21 deletions
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48
js/src/xpconnect/src/xpcwrappednative.cpp
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@ -1866,20 +1866,13 @@ XPCWrappedNative::CallMethod(XPCCallContext& ccx,
nsXPTCVariant paramBuffer[PARAM_BUFFER_COUNT];
// Number of nsAutoStrings to construct on the stack for use with method
// calls that use 'out' AStrings (aka [domstring]). These can save us from
// a new/delete of an nsString. But the cost is that the ctor/dtor code
// is run for each nsAutoString in the array for each call - whether or not
// a specific call actually uses *any* AStrings. Also, we have these
// large-ish nsAutoString objects using up stack space.
//
// Set this to zero to disable use of these auto strings.
#define PARAM_AUTOSTRING_COUNT 1
#if PARAM_AUTOSTRING_COUNT
nsVoidableString autoStrings[PARAM_AUTOSTRING_COUNT];
int autoStringIndex = 0;
#endif
// Reserve space on the stack for one nsAutoString. We don't want
// the string itself to be declared on the stack as that would
// make the ctor and dtors run for each pass through this code,
// and they're only needed in a fraction of all the calls that
// come through here.
char autoString[sizeof(nsAutoString)];
PRBool autoStringUsed = PR_FALSE;
JSBool retval = JS_FALSE;
@ -2118,19 +2111,24 @@ XPCWrappedNative::CallMethod(XPCCallContext& ccx,
// now and then continue in order to skip the call to
// JSData2Native
// If autoStrings array support is enabld, then use
// one of them if they are not already used up.
#if PARAM_AUTOSTRING_COUNT
if(autoStringIndex < PARAM_AUTOSTRING_COUNT)
if(!autoStringUsed)
{
// Our stack space for an nsAutoString is
// still available, initialize the string
// object (using placement new) and use
// it.
nsAutoString *s = (nsAutoString*)&autoString;
new (s) nsAutoString();
autoStringUsed = PR_TRUE;
// Don't call SetValIsDOMString because we don't
// want to delete this pointer.
dp->val.p = &autoStrings[autoStringIndex++];
dp->val.p = s;
continue;
}
#endif
dp->SetValIsDOMString();
if(!(dp->val.p = new nsVoidableString()))
if(!(dp->val.p = new nsAutoString()))
{
JS_ReportOutOfMemory(ccx);
goto done;
@ -2530,6 +2528,14 @@ done:
}
}
if (autoStringUsed) {
// Our stack based nsAutoString was used, clean it up.
nsAutoString *s = (nsAutoString*)&autoString;
s->~nsAutoString();
}
if(dispatchParams && dispatchParams != paramBuffer)
delete [] dispatchParams;