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         uint16_t 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: copy log messages exactly. If unset, check that the message
  42          *   is a single line, and add '\n' if missing.
  43          */
  44         unsigned exact_log_message : 1;
  45
  46         /* boolean: Prevent auto-compaction of tables. */
  47         unsigned disable_auto_compact : 1;
  48
  49         /*
  50          * Geometric sequence factor used by auto-compaction to decide which
  51          * tables to compact. Defaults to 2 if unset.
  52          */
  53         uint8_t auto_compaction_factor;
  54 };
  55
  56 /* reftable_block_stats holds statistics for a single block type */
  57 struct reftable_block_stats {
  58         /* total number of entries written */
  59         int entries;
  60         /* total number of key restarts */
  61         int restarts;
  62         /* total number of blocks */
  63         int blocks;
  64         /* total number of index blocks */
  65         int index_blocks;
  66         /* depth of the index */
  67         int max_index_level;
  68
  69         /* offset of the first block for this type */
  70         uint64_t offset;
  71         /* offset of the top level index block for this type, or 0 if not
  72          * present */
  73         uint64_t index_offset;
  74 };
  75
  76 /* stats holds overall statistics for a single reftable */
  77 struct reftable_stats {
  78         /* total number of blocks written. */
  79         int blocks;
  80         /* stats for ref data */
  81         struct reftable_block_stats ref_stats;
  82         /* stats for the SHA1 to ref map. */
  83         struct reftable_block_stats obj_stats;
  84         /* stats for index blocks */
  85         struct reftable_block_stats idx_stats;
  86         /* stats for log blocks */
  87         struct reftable_block_stats log_stats;
  88
  89         /* disambiguation length of shortened object IDs. */
  90         int object_id_len;
  91 };
  92
  93 /* reftable_new_writer creates a new writer */
  94 struct reftable_writer *
  95 reftable_new_writer(ssize_t (*writer_func)(void *, const void *, size_t),
  96                     int (*flush_func)(void *),
  97                     void *writer_arg, const struct reftable_write_options *opts);
  98
  99 /* Set the range of update indices for the records we will add. When writing a
 100    table into a stack, the min should be at least
 101    reftable_stack_next_update_index(), or REFTABLE_API_ERROR is returned.
 102
 103    For transactional updates to a stack, typically min==max, and the
 104    update_index can be obtained by inspeciting the stack. When converting an
 105    existing ref database into a single reftable, this would be a range of
 106    update-index timestamps.
 107  */
 108 void reftable_writer_set_limits(struct reftable_writer *w, uint64_t min,
 109                                 uint64_t max);
 110
 111 /*
 112   Add a reftable_ref_record. The record should have names that come after
 113   already added records.
 114
 115   The update_index must be within the limits set by
 116   reftable_writer_set_limits(), or REFTABLE_API_ERROR is returned. It is an
 117   REFTABLE_API_ERROR error to write a ref record after a log record.
 118 */
 119 int reftable_writer_add_ref(struct reftable_writer *w,
 120                             struct reftable_ref_record *ref);
 121
 122 /*
 123   Convenience function to add multiple reftable_ref_records; the function sorts
 124   the records before adding them, reordering the records array passed in.
 125 */
 126 int reftable_writer_add_refs(struct reftable_writer *w,
 127                              struct reftable_ref_record *refs, int n);
 128
 129 /*
 130   adds reftable_log_records. Log records are keyed by (refname, decreasing
 131   update_index). The key for the record added must come after the already added
 132   log records.
 133 */
 134 int reftable_writer_add_log(struct reftable_writer *w,
 135                             struct reftable_log_record *log);
 136
 137 /*
 138   Convenience function to add multiple reftable_log_records; the function sorts
 139   the records before adding them, reordering records array passed in.
 140 */
 141 int reftable_writer_add_logs(struct reftable_writer *w,
 142                              struct reftable_log_record *logs, int n);
 143
 144 /* reftable_writer_close finalizes the reftable. The writer is retained so
 145  * statistics can be inspected. */
 146 int reftable_writer_close(struct reftable_writer *w);
 147
 148 /* writer_stats returns the statistics on the reftable being written.
 149
 150    This struct becomes invalid when the writer is freed.
 151  */
 152 const struct reftable_stats *reftable_writer_stats(struct reftable_writer *w);
 153
 154 /* reftable_writer_free deallocates memory for the writer */
 155 void reftable_writer_free(struct reftable_writer *w);
 156
 157 #endif