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#ifndef PURE_LOG_H
#define PURE_LOG_H
#include "flow.h"
#include "result.h"
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
/* An app's log beside its store (store/store-log.c): an entry a save, its
* number (one more than the entry before), whether the save also committed
* the tree, and its payload. An entry counts once pure_log_append returns
* PURE_OK: it is on the device. One thread uses a log. */
typedef struct PureLog PureLog;
/* The log in directory (made empty when it has none). The entries found are
* checked (digests, numbers following on) up to the first that is not. */
PureResult pure_log_open(const char *directory, PureLog **out);
void pure_log_close(PureLog *);
/* The last entry's number (0: none). */
uint64_t pure_log_last(const PureLog *);
/* The entries from number from on (0: every entry kept), in order; payloads
* stay valid until the next append. STORE_ERROR when an entry from `from` on
* is missing; a visit that returns false stops. Only before appending. */
PureResult pure_log_read(PureLog *, uint64_t from,
bool (*visit)(void *, uint64_t seq, bool tree, PureSpan payload), void *context);
/* Entries after seq no longer count: the next append follows seq, over them. */
void pure_log_end(PureLog *, uint64_t seq);
/* Append the entry numbered seq (one more than the last) and make it durable:
* UNCERTAIN when writing or syncing failed (it may or may not be there). */
PureResult pure_log_append(PureLog *, uint64_t seq, bool tree, PureSpan payload);
/* The last appended entry no longer counts (its save failed after it was
* written): the next append takes its number and its place. */
void pure_log_retract(PureLog *);
/* Entries up to seq are no longer read: their segments may be used again. */
void pure_log_release(PureLog *, uint64_t seq);
/* Bytes of the segments that hold entries not released. */
uint64_t pure_log_bytes(const PureLog *);
/* A list's image: a file of directory named after the list, replaced whole
* (written beside it, synced, renamed over it): pure_image_write writes the
* bytes of parts one after another, pure_image_read gives them back (malloc'd;
* NOT_FOUND when there is none, STORE_ERROR when damaged). The bytes of the
* image are digested: a file cut short or changed is refused. */
PureResult pure_image_write(const char *directory, const char *name, const PureSpan *parts, size_t count);
PureResult pure_image_read(const char *directory, const char *name, unsigned char **bytes, size_t *size);
PureResult pure_image_remove(const char *directory, const char *name);
#endif
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