reftable/iter.h

   1 /*
   2 Copyright 2020 Google LLC
   3
   4 Use of this source code is governed by a BSD-style
   5 license that can be found in the LICENSE file or at
   6 https://developers.google.com/open-source/licenses/bsd
   7 */
   8
   9 #ifndef ITER_H
  10 #define ITER_H
  11
  12 #include "system.h"
  13 #include "block.h"
  14 #include "record.h"
  15
  16 #include "reftable-iterator.h"
  17
  18 /*
  19  * The virtual function table for implementing generic reftable iterators.
  20  */
  21 struct reftable_iterator_vtable {
  22         int (*seek)(void *iter_arg, struct reftable_record *want);
  23         int (*next)(void *iter_arg, struct reftable_record *rec);
  24         void (*close)(void *iter_arg);
  25 };
  26
  27 /*
  28  * Position the iterator at the wanted record such that a call to
  29  * `iterator_next()` would return that record, if it exists.
  30  */
  31 int iterator_seek(struct reftable_iterator *it, struct reftable_record *want);
  32
  33 /*
  34  * Yield the next record and advance the iterator. Returns <0 on error, 0 when
  35  * a record was yielded, and >0 when the iterator hit an error.
  36  */
  37 int iterator_next(struct reftable_iterator *it, struct reftable_record *rec);
  38
  39 /*
  40  * Set up the iterator such that it behaves the same as an iterator with no
  41  * entries.
  42  */
  43 void iterator_set_empty(struct reftable_iterator *it);
  44
  45 /* iterator that produces only ref records that point to `oid` */
  46 struct filtering_ref_iterator {
  47         struct strbuf oid;
  48         struct reftable_iterator it;
  49 };
  50 #define FILTERING_REF_ITERATOR_INIT \
  51         {                           \
  52                 .oid = STRBUF_INIT  \
  53         }
  54
  55 void iterator_from_filtering_ref_iterator(struct reftable_iterator *,
  56                                           struct filtering_ref_iterator *);
  57
  58 /* iterator that produces only ref records that point to `oid`,
  59  * but using the object index.
  60  */
  61 struct indexed_table_ref_iter {
  62         struct reftable_reader *r;
  63         struct strbuf oid;
  64
  65         /* mutable */
  66         uint64_t *offsets;
  67
  68         /* Points to the next offset to read. */
  69         int offset_idx;
  70         int offset_len;
  71         struct block_reader block_reader;
  72         struct block_iter cur;
  73         int is_finished;
  74 };
  75
  76 #define INDEXED_TABLE_REF_ITER_INIT { \
  77         .cur = BLOCK_ITER_INIT, \
  78         .oid = STRBUF_INIT, \
  79 }
  80
  81 void iterator_from_indexed_table_ref_iter(struct reftable_iterator *it,
  82                                           struct indexed_table_ref_iter *itr);
  83
  84 /* Takes ownership of `offsets` */
  85 int new_indexed_table_ref_iter(struct indexed_table_ref_iter **dest,
  86                                struct reftable_reader *r, uint8_t *oid,
  87                                int oid_len, uint64_t *offsets, int offset_len);
  88
  89 #endif