reftable/reftable-writer.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 REFTABLE_WRITER_H
  10 #define REFTABLE_WRITER_H
  11
  12 #include "reftable-record.h"
  13
  14 #include <stdint.h>
  15 #include <unistd.h> /* ssize_t */
  16
  17 /* Writing single reftables */
  18
  19 /* reftable_write_options sets options for writing a single reftable. */
  20 struct reftable_write_options {
  21         /* boolean: do not pad out blocks to block size. */
  22         unsigned unpadded : 1;
  23
  24         /* the blocksize. Should be less than 2^24. */
  25         uint32_t block_size;
  26
  27         /* boolean: do not generate a SHA1 => ref index. */
  28         unsigned skip_index_objects : 1;
  29
  30         /* how often to write complete keys in each block. */
  31         int restart_interval;
  32
  33         /* 4-byte identifier ("sha1", "s256") of the hash.
  34          * Defaults to SHA1 if unset
  35          */
  36         uint32_t hash_id;
  37
  38         /* boolean: do not check ref names for validity or dir/file conflicts.
  39          */
  40         unsigned skip_name_check : 1;
  41
  42         /* boolean: copy log messages exactly. If unset, check that the message
  43          *   is a single line, and add '\n' if missing.
  44          */
  45         unsigned exact_log_message : 1;
  46 };
  47
  48 /* reftable_block_stats holds statistics for a single block type */
  49 struct reftable_block_stats {
  50         /* total number of entries written */
  51         int entries;
  52         /* total number of key restarts */
  53         int restarts;
  54         /* total number of blocks */
  55         int blocks;
  56         /* total number of index blocks */
  57         int index_blocks;
  58         /* depth of the index */
  59         int max_index_level;
  60
  61         /* offset of the first block for this type */
  62         uint64_t offset;
  63         /* offset of the top level index block for this type, or 0 if not
  64          * present */
  65         uint64_t index_offset;
  66 };
  67
  68 /* stats holds overall statistics for a single reftable */
  69 struct reftable_stats {
  70         /* total number of blocks written. */
  71         int blocks;
  72         /* stats for ref data */
  73         struct reftable_block_stats ref_stats;
  74         /* stats for the SHA1 to ref map. */
  75         struct reftable_block_stats obj_stats;
  76         /* stats for index blocks */
  77         struct reftable_block_stats idx_stats;
  78         /* stats for log blocks */
  79         struct reftable_block_stats log_stats;
  80
  81         /* disambiguation length of shortened object IDs. */
  82         int object_id_len;
  83 };
  84
  85 /* reftable_new_writer creates a new writer */
  86 struct reftable_writer *
  87 reftable_new_writer(ssize_t (*writer_func)(void *, const void *, size_t),
  88                     void *writer_arg, struct reftable_write_options *opts);
  89
  90 /* Set the range of update indices for the records we will add. When writing a
  91    table into a stack, the min should be at least
  92    reftable_stack_next_update_index(), or REFTABLE_API_ERROR is returned.
  93
  94    For transactional updates to a stack, typically min==max, and the
  95    update_index can be obtained by inspeciting the stack. When converting an
  96    existing ref database into a single reftable, this would be a range of
  97    update-index timestamps.
  98  */
  99 void reftable_writer_set_limits(struct reftable_writer *w, uint64_t min,
 100                                 uint64_t max);
 101
 102 /*
 103   Add a reftable_ref_record. The record should have names that come after
 104   already added records.
 105
 106   The update_index must be within the limits set by
 107   reftable_writer_set_limits(), or REFTABLE_API_ERROR is returned. It is an
 108   REFTABLE_API_ERROR error to write a ref record after a log record.
 109 */
 110 int reftable_writer_add_ref(struct reftable_writer *w,
 111                             struct reftable_ref_record *ref);
 112
 113 /*
 114   Convenience function to add multiple reftable_ref_records; the function sorts
 115   the records before adding them, reordering the records array passed in.
 116 */
 117 int reftable_writer_add_refs(struct reftable_writer *w,
 118                              struct reftable_ref_record *refs, int n);
 119
 120 /*
 121   adds reftable_log_records. Log records are keyed by (refname, decreasing
 122   update_index). The key for the record added must come after the already added
 123   log records.
 124 */
 125 int reftable_writer_add_log(struct reftable_writer *w,
 126                             struct reftable_log_record *log);
 127
 128 /*
 129   Convenience function to add multiple reftable_log_records; the function sorts
 130   the records before adding them, reordering records array passed in.
 131 */
 132 int reftable_writer_add_logs(struct reftable_writer *w,
 133                              struct reftable_log_record *logs, int n);
 134
 135 /* reftable_writer_close finalizes the reftable. The writer is retained so
 136  * statistics can be inspected. */
 137 int reftable_writer_close(struct reftable_writer *w);
 138
 139 /* writer_stats returns the statistics on the reftable being written.
 140
 141    This struct becomes invalid when the writer is freed.
 142  */
 143 const struct reftable_stats *writer_stats(struct reftable_writer *w);
 144
 145 /* reftable_writer_free deallocates memory for the writer */
 146 void reftable_writer_free(struct reftable_writer *w);
 147
 148 #endif