NS_INTERFACE_MAP_END
//*****************************************************************************
// nsSHistory: nsISHistory
//*****************************************************************************
// static
PRUint32
nsSHistory::CalcMaxTotalViewers()
{
// Calculate an estimate of how many ContentViewers we should cache based
// on RAM. This assumes that the average ContentViewer is 4MB (conservative)
// and caps the max at 8 ContentViewers
//
// TODO: Should we split the cache memory betw. ContentViewer caching and
// nsCacheService?
//
// RAM ContentViewers
// -----------------------
// 32 Mb 0
// 64 Mb 1
// 128 Mb 2
// 256 Mb 3
// 512 Mb 5
// 1024 Mb 8
// 2048 Mb 8
// 4096 Mb 8
PRUint64 bytes = PR_GetPhysicalMemorySize();
if (LL_IS_ZERO(bytes))
return 0;
// Conversion from unsigned int64 to double doesn't work on all platforms.
// We need to truncate the value at LL_MAXINT to make sure we don't
// overflow.
if (LL_CMP(bytes, >, LL_MAXINT))
bytes = LL_MAXINT;
PRUint64 kbytes;
LL_SHR(kbytes, bytes, 10);
double kBytesD;
LL_L2D(kBytesD, (PRInt64) kbytes);
// This is essentially the same calculation as for nsCacheService,
// except that we divide the final memory calculation by 4, since
// we assume each ContentViewer takes on average 4MB
PRUint32 viewers = 0;
double x = log(kBytesD)/log(2.0) - 14;
if (x > 0) {
viewers = (PRUint32)(x * x - x + 2.001); // add .001 for rounding
viewers /= 4;
}
// Cap it off at 8 max
if (viewers > 8) {
viewers = 8;
}
return viewers;
}
static VALUE
RubyFrom64BitInt(PRUint64 aNative)
{
PRUint64 lo64, hi64;
LL_L2UI(lo64, aNative);
LL_SHR(hi64, aNative, 32);
{
VALUE lo = UINT2NUM(lo64);
VALUE hi = UINT2NUM(hi64);
VALUE hiRuby = rb_funcall(hi, id_lshift, 1, INT2FIX(32));
return rb_funcall(hiRuby, id_plus, 1, lo);
}
}
PR_IMPLEMENT(PRUint64) PR_htonll(PRUint64 n)
{
#ifdef IS_BIG_ENDIAN
return n;
#else
PRUint64 tmp;
PRUint32 hi, lo;
LL_L2UI(lo, n);
LL_SHR(tmp, n, 32);
LL_L2UI(hi, tmp);
hi = htonl(hi);
lo = htonl(lo);
LL_UI2L(n, lo);
LL_SHL(n, n, 32);
LL_UI2L(tmp, hi);
LL_ADD(n, n, tmp);
return n;
#endif
} /* htonll */
