121 lines
3.1 KiB
Rust
121 lines
3.1 KiB
Rust
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//! Operation log (OpLog) for tracking mutations.
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//!
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//! The OpLog records every write operation so that changes can be replayed,
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//! replicated, or used for change-stream style notifications.
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use std::sync::atomic::{AtomicU64, Ordering};
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use std::time::{SystemTime, UNIX_EPOCH};
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use bson::Document;
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use dashmap::DashMap;
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use serde::{Deserialize, Serialize};
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/// The type of operation recorded in the oplog.
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#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
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pub enum OpType {
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Insert,
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Update,
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Delete,
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}
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/// A single oplog entry.
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#[derive(Debug, Clone, Serialize, Deserialize)]
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pub struct OpLogEntry {
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/// Monotonically increasing sequence number.
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pub seq: u64,
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/// Timestamp in milliseconds since UNIX epoch.
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pub timestamp_ms: i64,
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/// Operation type.
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pub op: OpType,
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/// Database name.
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pub db: String,
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/// Collection name.
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pub collection: String,
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/// Document id (hex string).
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pub document_id: String,
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/// The document snapshot (for insert/update; None for delete).
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pub document: Option<Document>,
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}
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/// In-memory operation log.
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pub struct OpLog {
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/// All entries keyed by sequence number.
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entries: DashMap<u64, OpLogEntry>,
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/// Next sequence number.
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next_seq: AtomicU64,
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}
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impl OpLog {
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pub fn new() -> Self {
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Self {
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entries: DashMap::new(),
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next_seq: AtomicU64::new(1),
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}
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}
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/// Append an operation to the log and return its sequence number.
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pub fn append(
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&self,
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op: OpType,
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db: &str,
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collection: &str,
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document_id: &str,
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document: Option<Document>,
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) -> u64 {
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let seq = self.next_seq.fetch_add(1, Ordering::SeqCst);
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let entry = OpLogEntry {
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seq,
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timestamp_ms: SystemTime::now()
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.duration_since(UNIX_EPOCH)
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.unwrap()
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.as_millis() as i64,
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op,
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db: db.to_string(),
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collection: collection.to_string(),
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document_id: document_id.to_string(),
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document,
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};
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self.entries.insert(seq, entry);
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seq
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}
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/// Get all entries with sequence number >= `since`.
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pub fn entries_since(&self, since: u64) -> Vec<OpLogEntry> {
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let mut result: Vec<_> = self
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.entries
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.iter()
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.filter(|e| *e.key() >= since)
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.map(|e| e.value().clone())
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.collect();
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result.sort_by_key(|e| e.seq);
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result
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}
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/// Get the current (latest) sequence number. Returns 0 if empty.
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pub fn current_seq(&self) -> u64 {
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self.next_seq.load(Ordering::SeqCst).saturating_sub(1)
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}
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/// Clear all entries.
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pub fn clear(&self) {
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self.entries.clear();
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self.next_seq.store(1, Ordering::SeqCst);
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}
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/// Number of entries in the log.
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pub fn len(&self) -> usize {
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self.entries.len()
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}
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/// Whether the log is empty.
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pub fn is_empty(&self) -> bool {
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self.entries.is_empty()
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}
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}
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impl Default for OpLog {
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fn default() -> Self {
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Self::new()
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}
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}
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