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#include "packet.h"
#include "snapshot.h"
struct snapshot_delta
{
int num_deleted_items;
int num_update_items;
int num_temp_items; // needed?
int data[1];
/*
char *data_start() { return (char *)&offsets[num_deleted_items+num_update_items+num_temp_items]; }
int deleted_item(int index) { return offsets[index]; }
item *update_item(int index) { return (item *)(data_start() + offsets[num_deleted_items+index]); }
item *temp_item(int index) { return (item *)(data_start() + offsets[num_deleted_items+num_update_items+index]); }
* */
};
static const int MAX_ITEMS = 512;
static snapshot_delta empty = {0,0,0,{0}};
void *snapshot_empty_delta()
{
return ∅
}
static int diff_item(int *past, int *current, int *out, int size)
{
/*
int needed = 0;
while(size)
{
*out = *current-*past;
if(*out)
needed = 1;
out++;
current++;
past++;
size--;
}*/
int needed = 0;
while(size)
{
*out = *current-*past;
if(*out)
needed = 1;
out++;
past++;
current++;
size--;
}
return needed;
}
// 1 = 4-3
// d = n-p
// n(4) = p(3)+d(1)
static void undiff_item(int *past, int *diff, int *out, int size)
{
while(size)
{
*out = *past+*diff;
out++;
past++;
diff++;
size--;
}
}
int snapshot_create_delta(snapshot *from, snapshot *to, void *dstdata)
{
//int deleted[MAX_ITEMS];
//int update[MAX_ITEMS];
//int mark[MAX_ITEMS];
//char data[MAX_SNAPSHOT_SIZE];
snapshot_delta *delta = (snapshot_delta *)dstdata;
int *data = (int *)delta->data;
delta->num_deleted_items = 0;
delta->num_update_items = 0;
delta->num_temp_items = 0;
// pack deleted stuff
for(int i = 0; i < from->num_items; i++)
{
snapshot::item *fromitem = from->get_item(i);
if(to->get_item_index(fromitem->key()) == -1)
{
// deleted
delta->num_deleted_items++;
*data = fromitem->key();
data++;
}
}
// pack updated stuff
int count = 0, size_count = 0;
for(int i = 0; i < to->num_items; i++)
{
// do delta
int itemsize = to->get_item_datasize(i);
snapshot::item *curitem = to->get_item(i);
int pastindex = from->get_item_index(curitem->key());
if(pastindex != -1)
{
snapshot::item *pastitem = from->get_item(pastindex);
if(diff_item((int*)pastitem->data(), (int*)curitem->data(), data+3, itemsize/4))
{
*data++ = itemsize;
*data++ = curitem->type();
*data++ = curitem->id();
//*data++ = curitem->key();
data += itemsize/4;
delta->num_update_items++;
}
}
else
{
*data++ = itemsize;
*data++ = curitem->type();
*data++ = curitem->id();
//*data++ = curitem->key();
mem_copy(data, curitem->data(), itemsize);
size_count += itemsize;
data += itemsize/4;
delta->num_update_items++;
count++;
}
}
if(0)
{
dbg_msg("snapshot", "%d %d %d",
delta->num_deleted_items,
delta->num_update_items,
delta->num_temp_items);
}
// TODO: pack temp stuff
// finish
//mem_copy(delta->offsets, deleted, delta->num_deleted_items*sizeof(int));
//mem_copy(&(delta->offsets[delta->num_deleted_items]), update, delta->num_update_items*sizeof(int));
//mem_copy(&(delta->offsets[delta->num_deleted_items+delta->num_update_items]), temp, delta->num_temp_items*sizeof(int));
//mem_copy(delta->data_start(), data, data_size);
//delta->data_size = data_size;
if(!delta->num_deleted_items && !delta->num_update_items && !delta->num_temp_items)
return 0;
return (int)((char*)data-(char*)dstdata);
}
int snapshot_unpack_delta(snapshot *from, snapshot *to, void *srcdata, int data_size)
{
snapshot_builder builder;
snapshot_delta *delta = (snapshot_delta *)srcdata;
int *data = (int *)delta->data;
builder.start();
// unpack deleted stuff
int *deleted = data;
data += delta->num_deleted_items;
// copy all non deleted stuff
for(int i = 0; i < from->num_items; i++)
{
//dbg_assert(0, "fail!");
snapshot::item *fromitem = from->get_item(i);
int itemsize = from->get_item_datasize(i);
int keep = 1;
for(int d = 0; d < delta->num_deleted_items; d++)
{
if(deleted[d] == fromitem->key())
{
keep = 0;
break;
}
}
if(keep)
{
// keep it
int *newdata = (int *)(snapshot::item *)builder.new_item(fromitem->type(), fromitem->id(), itemsize);
mem_copy(newdata, fromitem->data(), itemsize);
}
}
// unpack updated stuff
for(int i = 0; i < delta->num_update_items; i++)
{
int itemsize, id, type, key;
itemsize = *data++;
//key = *data++;
type = *data++;
id = *data++;
key = (type<<16)|id;
// create the item if needed
int *newdata = builder.get_item_data(key);
if(!newdata)
newdata = (int *)builder.new_item(key>>16, key&0xffff, itemsize);
int fromindex = from->get_item_index(key);
if(fromindex != -1)
{
// we got an update so we need to apply the diff
int *pastdata = (int *)from->get_item(fromindex)->data();
undiff_item(pastdata, data, newdata, itemsize/4);
}
else // no previous, just copy the data
mem_copy(newdata, data, itemsize);
data += itemsize/4;
}
// TODO: unpack temp stuff
// finish up
return builder.finish(to);
}
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