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         /* Default mode for creating files. If unset, use 0666 (+umask) */
  39         unsigned int default_permissions;
  40
  41         /* boolean: do not check ref names for validity or dir/file conflicts.
  42          */
  43         unsigned skip_name_check : 1;
  44
  45         /* boolean: copy log messages exactly. If unset, check that the message
  46          *   is a single line, and add '\n' if missing.
  47          */
  48         unsigned exact_log_message : 1;
  49 };
  50
  51 /* reftable_block_stats holds statistics for a single block type */
  52 struct reftable_block_stats {
  53         /* total number of entries written */
  54         int entries;
  55         /* total number of key restarts */
  56         int restarts;
  57         /* total number of blocks */
  58         int blocks;
  59         /* total number of index blocks */
  60         int index_blocks;
  61         /* depth of the index */
  62         int max_index_level;
  63
  64         /* offset of the first block for this type */
  65         uint64_t offset;
  66         /* offset of the top level index block for this type, or 0 if not
  67          * present */
  68         uint64_t index_offset;
  69 };
  70
  71 /* stats holds overall statistics for a single reftable */
  72 struct reftable_stats {
  73         /* total number of blocks written. */
  74         int blocks;
  75         /* stats for ref data */
  76         struct reftable_block_stats ref_stats;
  77         /* stats for the SHA1 to ref map. */
  78         struct reftable_block_stats obj_stats;
  79         /* stats for index blocks */
  80         struct reftable_block_stats idx_stats;
  81         /* stats for log blocks */
  82         struct reftable_block_stats log_stats;
  83
  84         /* disambiguation length of shortened object IDs. */
  85         int object_id_len;
  86 };
  87
  88 /* reftable_new_writer creates a new writer */
  89 struct reftable_writer *
  90 reftable_new_writer(ssize_t (*writer_func)(void *, const void *, size_t),
  91                     int (*flush_func)(void *),
  92                     void *writer_arg, struct reftable_write_options *opts);
  93
  94 /* Set the range of update indices for the records we will add. When writing a
  95    table into a stack, the min should be at least
  96    reftable_stack_next_update_index(), or REFTABLE_API_ERROR is returned.
  97
  98    For transactional updates to a stack, typically min==max, and the
  99    update_index can be obtained by inspeciting the stack. When converting an
 100    existing ref database into a single reftable, this would be a range of
 101    update-index timestamps.
 102  */
 103 void reftable_writer_set_limits(struct reftable_writer *w, uint64_t min,
 104                                 uint64_t max);
 105
 106 /*
 107   Add a reftable_ref_record. The record should have names that come after
 108   already added records.
 109
 110   The update_index must be within the limits set by
 111   reftable_writer_set_limits(), or REFTABLE_API_ERROR is returned. It is an
 112   REFTABLE_API_ERROR error to write a ref record after a log record.
 113 */
 114 int reftable_writer_add_ref(struct reftable_writer *w,
 115                             struct reftable_ref_record *ref);
 116
 117 /*
 118   Convenience function to add multiple reftable_ref_records; the function sorts
 119   the records before adding them, reordering the records array passed in.
 120 */
 121 int reftable_writer_add_refs(struct reftable_writer *w,
 122                              struct reftable_ref_record *refs, int n);
 123
 124 /*
 125   adds reftable_log_records. Log records are keyed by (refname, decreasing
 126   update_index). The key for the record added must come after the already added
 127   log records.
 128 */
 129 int reftable_writer_add_log(struct reftable_writer *w,
 130                             struct reftable_log_record *log);
 131
 132 /*
 133   Convenience function to add multiple reftable_log_records; the function sorts
 134   the records before adding them, reordering records array passed in.
 135 */
 136 int reftable_writer_add_logs(struct reftable_writer *w,
 137                              struct reftable_log_record *logs, int n);
 138
 139 /* reftable_writer_close finalizes the reftable. The writer is retained so
 140  * statistics can be inspected. */
 141 int reftable_writer_close(struct reftable_writer *w);
 142
 143 /* writer_stats returns the statistics on the reftable being written.
 144
 145    This struct becomes invalid when the writer is freed.
 146  */
 147 const struct reftable_stats *reftable_writer_stats(struct reftable_writer *w);
 148
 149 /* reftable_writer_free deallocates memory for the writer */
 150 void reftable_writer_free(struct reftable_writer *w);
 151
 152 #endif