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145 lines (134 loc) · 4.92 KB
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/* Licensed under BSD-MIT - see LICENSE file for details */
#ifndef CCAN_INVBLOOM_H
#define CCAN_INVBLOOM_H
#include <ccan/short_types/short_types.h>
#include <ccan/typesafe_cb/typesafe_cb.h>
#include <ccan/tal/tal.h>
struct invbloom {
size_t n_elems;
size_t id_size;
u32 salt;
s32 *count; /* [n_elems] */
u8 *idsum; /* [n_elems][id_size] */
void (*singleton)(struct invbloom *ib, size_t elem, bool, void *);
void *singleton_data;
};
/**
* invbloom_new - create a new invertable bloom lookup table
* @ctx: context to tal() from, or NULL.
* @type: type to place into the buckets (must not contain padding)
* @n_elems: number of entries in table
* @salt: 32 bit seed for table
*
* Returns a new table, which can be freed with tal_free().
*/
#define invbloom_new(ctx, type, n_elems, salt) \
invbloom_new_((ctx), sizeof(type), (n_elems), (salt))
struct invbloom *invbloom_new_(const tal_t *ctx,
size_t id_size,
size_t n_elems, u32 salt);
/**
* invbloom_singleton_cb - set callback for a singleton created/destroyed.
* @ib: the invertable bloom lookup table.
* @cb: the function to call (or NULL for none)
* @data: the data to hand to the function.
*
* This may be called by any function which mutates the table,
* possibly multiple times for a single call. The particular
* @ib bucket will be consistent, but the rest of the table may
* not be.
*
* @cb is of form "void @cb(struct invbloom *ib, size_t bucket, bool
* before, data)". @before is true if the call is done before the
* singleton in @bucket is removed (ie. ib->counts[bucket] is -1 or 1,
* but is about to change). @before is false if the call is done
* after the operation, and the bucket is now a singleton.
*/
#define invbloom_singleton_cb(ib, cb, data) \
invbloom_singleton_cb_((ib), \
typesafe_cb_preargs(void, void *, (cb), (data), \
struct invbloom *, size_t, bool), (data))
void invbloom_singleton_cb_(struct invbloom *ib,
void (*cb)(struct invbloom *,
size_t bucket, bool before, void *),
void *data);
/**
* invbloom_insert - add a new element
* @ib: the invertable bloom lookup table.
* @elem: the element
*
* This is guaranteed to be the inverse of invbloom_delete.
*/
void invbloom_insert(struct invbloom *ib, const void *elem);
/**
* invbloom_delete - remove an element
* @ib: the invertable bloom lookup table.
* @elem: the element
*
* Note that this doesn't check the element was previously added (as
* that can not be done in general anyway).
*
* This is guaranteed to be the inverse of invbloom_delete.
*/
void invbloom_delete(struct invbloom *ib, const void *elem);
/**
* invbloom_get - check if an element is (probably) in the table.
* @ib: the invertable bloom lookup table.
* @elem: the element
*
* This may return a false negative if the table is too full.
*
* It will only return a false positive if deletions and insertions
* don't match, and have managed to produce a result which matches the
* element. This is much less likely.
*/
bool invbloom_get(const struct invbloom *ib, const void *elem);
/**
* invbloom_extract - try to recover an entry added to a bloom lookup table.
* @ctx: the context to tal() the return value from.
* @ib: the invertable bloom lookup table.
*
* This may be able to recover (and delete) an element which was
* invbloom_insert()ed into the table (and not deleted). This will
* not work if the table is too full.
*
* It may return a bogus element if deletions and insertions don't
* match.
*/
void *invbloom_extract(const tal_t *ctx, struct invbloom *ib);
/**
* invbloom_extract_negative - try to recover an entry deleted from a bloom lookup table.
* @ctx: the context to tal() the return value from.
* @ib: the invertable bloom lookup table.
*
* This may be able to recover (and insert/undo) an element which was
* invbloom_delete()ed from the table (and not inserted). This will
* not work if the table is too full.
*
* It may return a bogus element if deletions and insertions don't
* match.
*/
void *invbloom_extract_negative(const tal_t *ctx, struct invbloom *ib);
/**
* invbloom_subtract - return the differences of two IBLTs.
* @ib1: the invertable bloom lookup table to alter
* @ib2: the invertable bloom lookup table to subtract.
*
* This produces exactly the same result as if a new table had all the
* elements only in @ib1 inserted, then all the elements onlt in @ib2
* deleted.
*
* ie. if @ib1 and @ib2 are similar, the result may be a usable by
* invbloom_extract and invbloom_extract_negative.
*/
void invbloom_subtract(struct invbloom *ib1, const struct invbloom *ib2);
/**
* invbloom_empty - is an invertable bloom lookup table completely clean?
* @ib: the invertable bloom lookup table
*
* This is always true if @ib has had the same elements inserted and
* deleted. It is far less likely to be true if different ones were
* deleted than inserted.
*/
bool invbloom_empty(const struct invbloom *ib);
#endif /* CCAN_INVBLOOM_H */