| Message ID | 20160930161013.9832-9-rkrcmar@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, 30 Sep 2016 18:10:13 +0200 Radim Krčmář <rkrcmar@redhat.com> wrote: > Assume that KVM would have returned the same on subsequent runs. > Abstract the memoizaiton pattern into macros. s/memoi/memori/i Throughout whole patch > > Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> > --- > target-i386/kvm.c | 21 +++++++++++++++++++-- > 1 file changed, 19 insertions(+), 2 deletions(-) > > diff --git a/target-i386/kvm.c b/target-i386/kvm.c > index 0fd664648665..113c5bf058ba 100644 > --- a/target-i386/kvm.c > +++ b/target-i386/kvm.c > @@ -129,10 +129,27 @@ static bool kvm_x2apic_api_set_flags(uint64_t flags) > return !kvm_vm_enable_cap(s, KVM_CAP_X2APIC_API, 0, flags); > } > > +#define MEMOIZE_RESULT(_result, _fn) \ > + ({ \ > + static bool _memoized; \ > + if (_memoized) { \ > + return _result; \ > + } \ > + _memoized = true; \ > + _result = _fn; \ > + }) > + > +#define MEMOIZE(_fn) \ > + ({ \ > + static typeof(_fn) _result; \ > + MEMOIZE_RESULT(_result, _fn); \ > + }) > + > bool kvm_enable_x2apic(void) > { > - return kvm_x2apic_api_set_flags(KVM_X2APIC_API_USE_32BIT_IDS | > - KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK); > + return MEMOIZE( > + kvm_x2apic_api_set_flags(KVM_X2APIC_API_USE_32BIT_IDS | > + KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK)); > } > > static int kvm_get_tsc(CPUState *cs)
2016-10-04 13:33+0200, Igor Mammedov: > On Fri, 30 Sep 2016 18:10:13 +0200 > Radim Krčmář <rkrcmar@redhat.com> wrote: >> Assume that KVM would have returned the same on subsequent runs. >> Abstract the memoizaiton pattern into macros. > s/memoi/memori/i > Throughout whole patch The pattern I wanted to describe is known as "memoization" without r, due to reasons, https://en.wikipedia.org/wiki/Memoization, but I was expecting the whole idea to be nacked, so the naming didn't get much thought. :) I'll change it memorize, to create less confusion. (Memoizing a non-pure "function" is hacky anyway.) Thanks.
diff --git a/target-i386/kvm.c b/target-i386/kvm.c index 0fd664648665..113c5bf058ba 100644 --- a/target-i386/kvm.c +++ b/target-i386/kvm.c @@ -129,10 +129,27 @@ static bool kvm_x2apic_api_set_flags(uint64_t flags) return !kvm_vm_enable_cap(s, KVM_CAP_X2APIC_API, 0, flags); } +#define MEMOIZE_RESULT(_result, _fn) \ + ({ \ + static bool _memoized; \ + if (_memoized) { \ + return _result; \ + } \ + _memoized = true; \ + _result = _fn; \ + }) + +#define MEMOIZE(_fn) \ + ({ \ + static typeof(_fn) _result; \ + MEMOIZE_RESULT(_result, _fn); \ + }) + bool kvm_enable_x2apic(void) { - return kvm_x2apic_api_set_flags(KVM_X2APIC_API_USE_32BIT_IDS | - KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK); + return MEMOIZE( + kvm_x2apic_api_set_flags(KVM_X2APIC_API_USE_32BIT_IDS | + KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK)); } static int kvm_get_tsc(CPUState *cs)
Assume that KVM would have returned the same on subsequent runs. Abstract the memoizaiton pattern into macros. Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> --- target-i386/kvm.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-)