Editing RSS fractions accounting
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Latest revision | Your text | ||
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In a C-like notation this would look like this: | In a C-like notation this would look like this: | ||
− | < | + | <pre> |
pb = lookup_pb(page, UB); | pb = lookup_pb(page, UB); | ||
if (pb != NULL) { | if (pb != NULL) { | ||
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list_add_tail(pb, page.pb_list); | list_add_tail(pb, page.pb_list); | ||
page.pb_list.first = head.next; | page.pb_list.first = head.next; | ||
− | </ | + | </pre> |
− | Shift increment essentially means | + | Shift increment essentially means <em>take one half of the currently held fraction and give it to the newbie</em>. |
=== Removing an existing reference === | === Removing an existing reference === | ||
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; The last reference is removed | ; The last reference is removed | ||
: In this case the PB that ties page and UB must give its shift back to other PBs and be removed from list. This “giving shift back” procedure may involve three PBs and it is better described by the code example below. | : In this case the PB that ties page and UB must give its shift back to other PBs and be removed from list. This “giving shift back” procedure may involve three PBs and it is better described by the code example below. | ||
− | < | + | <pre> |
pb = lookup_pb(page, UB); | pb = lookup_pb(page, UB); | ||
pb.refcount--; | pb.refcount--; | ||
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page.pb_list.first = tail | page.pb_list.first = tail | ||
} | } | ||
− | </ | + | </pre> |
Decrementing the shifts like this means “take the fraction held by the PB going out and give it to another one; if the fraction held is too large — share it between two PBs”. | Decrementing the shifts like this means “take the fraction held by the PB going out and give it to another one; if the fraction held is too large — share it between two PBs”. | ||
{{Note|cases when <code>page.pb_list</code> is becoming empty on adding a reference, or becoming empty on removing references are skipped to simplify the code examples.}} | {{Note|cases when <code>page.pb_list</code> is becoming empty on adding a reference, or becoming empty on removing references are skipped to simplify the code examples.}} | ||
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