thin-provisioning-tools/caching/hint_array.cc

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#include "caching/hint_array.h"
using namespace boost;
using namespace caching;
using namespace caching::hint_array_damage;
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using namespace persistent_data;
//----------------------------------------------------------------
namespace {
template <uint32_t WIDTH>
struct hint_traits {
typedef unsigned char byte;
typedef byte disk_type[WIDTH];
typedef vector<byte> value_type;
typedef no_op_ref_counter<value_type> ref_counter;
// FIXME: slow copying for now
static void unpack(disk_type const &disk, value_type &value) {
value.resize(WIDTH);
for (unsigned byte = 0; byte < WIDTH; byte++)
value.at(byte) = disk[byte];
}
static void pack(value_type const &value, disk_type &disk) {
for (unsigned byte = 0; byte < WIDTH; byte++)
disk[byte] = value.at(byte);
}
};
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// We've got into a bit of a mess here. Templates are compile
// time, and we don't know the hint width until run time. We're
// going to have to provide specialisation for all legal widths and
// use the appropriate one.
#define all_widths \
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xx(4);
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template <uint32_t WIDTH>
shared_ptr<array_base> mk_array(transaction_manager &tm) {
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typedef hint_traits<WIDTH> traits;
typedef array<traits> ha;
shared_ptr<array_base> r = typename ha::ptr(new ha(tm, typename traits::ref_counter()));
return r;
}
shared_ptr<array_base> mk_array(transaction_manager &tm, uint32_t width) {
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switch (width) {
#define xx(n) case n: return mk_array<n>(tm)
all_widths
#undef xx
default:
throw runtime_error("invalid hint width");
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}
// never get here
return shared_ptr<array_base>();
}
//--------------------------------
template <typename HA>
shared_ptr<HA>
downcast_array(shared_ptr<array_base> base) {
shared_ptr<HA> a = dynamic_pointer_cast<HA>(base);
if (!a)
throw runtime_error("internal error: couldn't cast hint array");
return a;
}
//--------------------------------
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template <uint32_t WIDTH>
shared_ptr<array_base> mk_array(transaction_manager &tm, block_address root, unsigned nr_entries) {
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typedef hint_traits<WIDTH> traits;
typedef array<traits> ha;
shared_ptr<array_base> r = typename ha::ptr(new ha(tm, typename traits::ref_counter(), root, nr_entries));
return r;
}
shared_ptr<array_base> mk_array(transaction_manager &tm, uint32_t width, block_address root, unsigned nr_entries) {
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switch (width) {
#define xx(n) case n: return mk_array<n>(tm, root, nr_entries)
all_widths
#undef xx
default:
throw runtime_error("invalid hint width");
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}
// never get here
return shared_ptr<array_base>();
}
//--------------------------------
template <uint32_t WIDTH>
void get_hint(shared_ptr<array_base> base, unsigned index, vector<unsigned char> &data) {
typedef hint_traits<WIDTH> traits;
typedef array<traits> ha;
shared_ptr<ha> a = downcast_array<ha>(base);
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data = a->get(index);
}
void get_hint_(uint32_t width, shared_ptr<array_base> base, unsigned index, vector<unsigned char> &data) {
switch (width) {
#define xx(n) case n: return get_hint<n>(base, index, data)
all_widths
#undef xx
}
}
//--------------------------------
template <uint32_t WIDTH>
void set_hint(shared_ptr<array_base> base, unsigned index, vector<unsigned char> const &data) {
typedef hint_traits<WIDTH> traits;
typedef array<traits> ha;
shared_ptr<ha> a = downcast_array<ha>(base);
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a->set(index, data);
}
void set_hint_(uint32_t width, shared_ptr<array_base> base,
unsigned index, vector<unsigned char> const &data) {
switch (width) {
#define xx(n) case n: return set_hint<n>(base, index, data)
all_widths
#undef xx
}
}
//--------------------------------
template <uint32_t WIDTH>
void grow(shared_ptr<array_base> base, unsigned new_nr_entries, vector<unsigned char> const &value) {
typedef hint_traits<WIDTH> traits;
typedef array<traits> ha;
shared_ptr<ha> a = downcast_array<ha>(base);
a->grow(new_nr_entries, value);
}
void grow_(uint32_t width, shared_ptr<array_base> base,
unsigned new_nr_entries, vector<unsigned char> const &value)
{
switch (width) {
#define xx(n) case n: return grow<n>(base, new_nr_entries, value)
all_widths
#undef xx
}
}
//--------------------------------
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class value_adapter {
public:
value_adapter(hint_visitor &v)
: v_(v) {
}
virtual void visit(uint32_t index, std::vector<unsigned char> const &v) {
v_.visit(static_cast<block_address>(index), v);
}
private:
hint_visitor &v_;
};
struct no_op_visitor : public hint_visitor {
virtual void visit(block_address cblock, std::vector<unsigned char> const &v) {
}
};
class ll_damage_visitor {
public:
ll_damage_visitor(damage_visitor &v)
: v_(v) {
}
virtual void visit(array_detail::damage const &d) {
v_.visit(missing_hints(d.desc_, d.lost_keys_));
}
private:
damage_visitor &v_;
};
template <uint32_t WIDTH>
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void walk_hints(shared_ptr<array_base> base, hint_visitor &hv, damage_visitor &dv) {
typedef hint_traits<WIDTH> traits;
typedef array<traits> ha;
shared_ptr<ha> a = downcast_array<ha>(base);
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value_adapter vv(hv);
ll_damage_visitor ll(dv);
a->visit_values(vv, ll);
}
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void walk_hints_(uint32_t width, shared_ptr<array_base> base,
hint_visitor &hv, damage_visitor &dv) {
switch (width) {
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#define xx(n) case n: walk_hints<n>(base, hv, dv); break
all_widths
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#undef xx
}
}
}
//----------------------------------------------------------------
missing_hints::missing_hints(std::string const desc, run<uint32_t> const &keys)
: damage(desc),
keys_(keys)
{
}
void
missing_hints::visit(damage_visitor &v) const
{
v.visit(*this);
}
//----------------------------------------------------------------
hint_array::hint_array(transaction_manager &tm, unsigned width)
: width_(check_width(width)),
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impl_(mk_array(tm, width))
{
}
hint_array::hint_array(transaction_manager &tm, unsigned width,
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block_address root, unsigned nr_entries)
: width_(check_width(width)),
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impl_(mk_array(tm, width, root, nr_entries))
{
}
block_address
hint_array::get_root() const
{
return impl_->get_root();
}
void
hint_array::get_hint(unsigned index, vector<unsigned char> &data) const
{
get_hint_(width_, impl_, index, data);
}
void
hint_array::set_hint(unsigned index, vector<unsigned char> const &data)
{
set_hint_(width_, impl_, index, data);
}
void
hint_array::grow(unsigned new_nr_entries, vector<unsigned char> const &value)
{
grow_(width_, impl_, new_nr_entries, value);
}
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void
hint_array::walk(hint_visitor &hv, hint_array_damage::damage_visitor &dv)
{
walk_hints_(width_, impl_, hv, dv);
}
void
hint_array::check(hint_array_damage::damage_visitor &visitor)
{
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no_op_visitor vv;
walk(vv, visitor);
}
uint32_t
hint_array::check_width(uint32_t width)
{
if (width % 4 || width == 0 || width > 128) {
ostringstream msg;
msg << "invalid hint width: " << width;
throw runtime_error(msg.str());
}
return width;
}
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//----------------------------------------------------------------