Line data Source code
1 : use std::sync::Arc;
2 :
3 : use anyhow::{bail, Result};
4 : use camino::Utf8PathBuf;
5 :
6 : use postgres_ffi::{MAX_SEND_SIZE, WAL_SEGMENT_SIZE};
7 : use tokio::{
8 : fs::OpenOptions,
9 : io::{AsyncSeekExt, AsyncWriteExt},
10 : };
11 : use tracing::{info, warn};
12 : use utils::{id::TenantTimelineId, lsn::Lsn};
13 :
14 : use crate::{
15 : control_file::FileStorage,
16 : state::TimelinePersistentState,
17 : timeline::{Timeline, TimelineError, WalResidentTimeline},
18 : timelines_global_map::{create_temp_timeline_dir, validate_temp_timeline},
19 : wal_backup::copy_s3_segments,
20 : wal_storage::{wal_file_paths, WalReader},
21 : GlobalTimelines,
22 : };
23 :
24 : // we don't want to have more than 10 segments on disk after copy, because they take space
25 : const MAX_BACKUP_LAG: u64 = 10 * WAL_SEGMENT_SIZE as u64;
26 :
27 : pub struct Request {
28 : pub source: Arc<Timeline>,
29 : pub until_lsn: Lsn,
30 : pub destination_ttid: TenantTimelineId,
31 : }
32 :
33 0 : pub async fn handle_request(request: Request) -> Result<()> {
34 0 : // TODO: request.until_lsn MUST be a valid LSN, and we cannot check it :(
35 0 : // if LSN will point to the middle of a WAL record, timeline will be in "broken" state
36 0 :
37 0 : match GlobalTimelines::get(request.destination_ttid) {
38 : // timeline already exists. would be good to check that this timeline is the copy
39 : // of the source timeline, but it isn't obvious how to do that
40 0 : Ok(_) => return Ok(()),
41 : // timeline not found, we are going to create it
42 0 : Err(TimelineError::NotFound(_)) => {}
43 : // error, probably timeline was deleted
44 0 : res => {
45 0 : res?;
46 : }
47 : }
48 :
49 0 : let source_tli = request.source.wal_residence_guard().await?;
50 :
51 0 : let conf = &GlobalTimelines::get_global_config();
52 0 : let ttid = request.destination_ttid;
53 :
54 0 : let (_tmp_dir, tli_dir_path) = create_temp_timeline_dir(conf, ttid).await?;
55 :
56 0 : let (mem_state, state) = source_tli.get_state().await;
57 0 : let start_lsn = state.timeline_start_lsn;
58 0 : if start_lsn == Lsn::INVALID {
59 0 : bail!("timeline is not initialized");
60 0 : }
61 0 : let backup_lsn = mem_state.backup_lsn;
62 0 :
63 0 : {
64 0 : let commit_lsn = mem_state.commit_lsn;
65 0 : let flush_lsn = source_tli.get_flush_lsn().await;
66 :
67 0 : info!(
68 0 : "collected info about source timeline: start_lsn={}, backup_lsn={}, commit_lsn={}, flush_lsn={}",
69 : start_lsn, backup_lsn, commit_lsn, flush_lsn
70 : );
71 :
72 0 : assert!(backup_lsn >= start_lsn);
73 0 : assert!(commit_lsn >= start_lsn);
74 0 : assert!(flush_lsn >= start_lsn);
75 :
76 0 : if request.until_lsn > flush_lsn {
77 0 : bail!(format!(
78 0 : "requested LSN {} is beyond the end of the timeline {}",
79 0 : request.until_lsn, flush_lsn
80 0 : ));
81 0 : }
82 0 : if request.until_lsn < start_lsn {
83 0 : bail!(format!(
84 0 : "requested LSN {} is before the start of the timeline {}",
85 0 : request.until_lsn, start_lsn
86 0 : ));
87 0 : }
88 0 :
89 0 : if request.until_lsn > commit_lsn {
90 0 : warn!("copy_timeline WAL is not fully committed");
91 0 : }
92 :
93 0 : if backup_lsn < request.until_lsn && request.until_lsn.0 - backup_lsn.0 > MAX_BACKUP_LAG {
94 : // we have a lot of segments that are not backed up. we can try to wait here until
95 : // segments will be backed up to remote storage, but it's not clear how long to wait
96 0 : bail!("too many segments are not backed up");
97 0 : }
98 0 : }
99 0 :
100 0 : let wal_seg_size = state.server.wal_seg_size as usize;
101 0 : if wal_seg_size == 0 {
102 0 : bail!("wal_seg_size is not set");
103 0 : }
104 0 :
105 0 : let first_segment = start_lsn.segment_number(wal_seg_size);
106 0 : let last_segment = request.until_lsn.segment_number(wal_seg_size);
107 :
108 0 : let new_backup_lsn = {
109 : // we can't have new backup_lsn greater than existing backup_lsn or start of the last segment
110 0 : let max_backup_lsn = backup_lsn.min(Lsn(last_segment * wal_seg_size as u64));
111 0 :
112 0 : if max_backup_lsn <= start_lsn {
113 : // probably we are starting from the first segment, which was not backed up yet.
114 : // note that start_lsn can be in the middle of the segment
115 0 : start_lsn
116 : } else {
117 : // we have some segments backed up, so we will assume all WAL below max_backup_lsn is backed up
118 0 : assert!(max_backup_lsn.segment_offset(wal_seg_size) == 0);
119 0 : max_backup_lsn
120 : }
121 : };
122 :
123 : // all previous segments will be copied inside S3
124 0 : let first_ondisk_segment = new_backup_lsn.segment_number(wal_seg_size);
125 0 : assert!(first_ondisk_segment <= last_segment);
126 0 : assert!(first_ondisk_segment >= first_segment);
127 :
128 0 : copy_s3_segments(
129 0 : wal_seg_size,
130 0 : &request.source.ttid,
131 0 : &request.destination_ttid,
132 0 : first_segment,
133 0 : first_ondisk_segment,
134 0 : )
135 0 : .await?;
136 :
137 0 : copy_disk_segments(
138 0 : &source_tli,
139 0 : wal_seg_size,
140 0 : new_backup_lsn,
141 0 : request.until_lsn,
142 0 : &tli_dir_path,
143 0 : )
144 0 : .await?;
145 :
146 0 : let mut new_state = TimelinePersistentState::new(
147 0 : &request.destination_ttid,
148 0 : state.server.clone(),
149 0 : vec![],
150 0 : request.until_lsn,
151 0 : start_lsn,
152 0 : )?;
153 0 : new_state.timeline_start_lsn = start_lsn;
154 0 : new_state.peer_horizon_lsn = request.until_lsn;
155 0 : new_state.backup_lsn = new_backup_lsn;
156 0 :
157 0 : FileStorage::create_new(&tli_dir_path, new_state.clone(), conf.no_sync).await?;
158 :
159 : // now we have a ready timeline in a temp directory
160 0 : validate_temp_timeline(conf, request.destination_ttid, &tli_dir_path).await?;
161 0 : GlobalTimelines::load_temp_timeline(request.destination_ttid, &tli_dir_path, true).await?;
162 :
163 0 : Ok(())
164 0 : }
165 :
166 0 : async fn copy_disk_segments(
167 0 : tli: &WalResidentTimeline,
168 0 : wal_seg_size: usize,
169 0 : start_lsn: Lsn,
170 0 : end_lsn: Lsn,
171 0 : tli_dir_path: &Utf8PathBuf,
172 0 : ) -> Result<()> {
173 0 : let mut wal_reader = tli.get_walreader(start_lsn).await?;
174 :
175 0 : let mut buf = vec![0u8; MAX_SEND_SIZE];
176 0 :
177 0 : let first_segment = start_lsn.segment_number(wal_seg_size);
178 0 : let last_segment = end_lsn.segment_number(wal_seg_size);
179 :
180 0 : for segment in first_segment..=last_segment {
181 0 : let segment_start = segment * wal_seg_size as u64;
182 0 : let segment_end = segment_start + wal_seg_size as u64;
183 0 :
184 0 : let copy_start = segment_start.max(start_lsn.0);
185 0 : let copy_end = segment_end.min(end_lsn.0);
186 0 :
187 0 : let copy_start = copy_start - segment_start;
188 0 : let copy_end = copy_end - segment_start;
189 :
190 0 : let wal_file_path = {
191 0 : let (normal, partial) = wal_file_paths(tli_dir_path, segment, wal_seg_size);
192 0 :
193 0 : if segment == last_segment {
194 0 : partial
195 : } else {
196 0 : normal
197 : }
198 : };
199 :
200 0 : write_segment(
201 0 : &mut buf,
202 0 : &wal_file_path,
203 0 : wal_seg_size as u64,
204 0 : copy_start,
205 0 : copy_end,
206 0 : &mut wal_reader,
207 0 : )
208 0 : .await?;
209 : }
210 :
211 0 : Ok(())
212 0 : }
213 :
214 0 : async fn write_segment(
215 0 : buf: &mut [u8],
216 0 : file_path: &Utf8PathBuf,
217 0 : wal_seg_size: u64,
218 0 : from: u64,
219 0 : to: u64,
220 0 : reader: &mut WalReader,
221 0 : ) -> Result<()> {
222 0 : assert!(from <= to);
223 0 : assert!(to <= wal_seg_size);
224 :
225 : #[allow(clippy::suspicious_open_options)]
226 0 : let mut file = OpenOptions::new()
227 0 : .create(true)
228 0 : .write(true)
229 0 : .open(&file_path)
230 0 : .await?;
231 :
232 : // maybe fill with zeros, as in wal_storage.rs?
233 0 : file.set_len(wal_seg_size).await?;
234 0 : file.seek(std::io::SeekFrom::Start(from)).await?;
235 :
236 0 : let mut bytes_left = to - from;
237 0 : while bytes_left > 0 {
238 0 : let len = bytes_left as usize;
239 0 : let len = len.min(buf.len());
240 0 : let len = reader.read(&mut buf[..len]).await?;
241 0 : file.write_all(&buf[..len]).await?;
242 0 : bytes_left -= len as u64;
243 : }
244 :
245 0 : file.flush().await?;
246 0 : file.sync_all().await?;
247 0 : Ok(())
248 0 : }
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