feat: hide older metadata update events

This updates the database schema to support hiding events.  In this
case, we are hiding older metadata updates when an author provides an
updated event.

Fixes https://todo.sr.ht/~gheartsfield/nostr-rs-relay/11

src/db.rs

@@ -13,6 +13,13 @@ use tokio::task;
 /// Database file
 const DB_FILE: &str = "nostr.db";
 
+/// Startup DB Pragmas
+const STARTUP_SQL: &str = r##"
+PRAGMA main.synchronous=NORMAL;
+PRAGMA foreign_keys = ON;
+pragma mmap_size = 536870912; -- 512MB of mmap
+"##;
+
 /// Schema definition
 const INIT_SQL: &str = r##"
 -- Database settings
@@ -21,8 +28,7 @@ PRAGMA journal_mode=WAL;
 PRAGMA main.synchronous=NORMAL;
 PRAGMA foreign_keys = ON;
 PRAGMA application_id = 1654008667;
-PRAGMA user_version = 1;
-pragma mmap_size = 536870912; -- 512MB of mmap
+PRAGMA user_version = 2;
 
 -- Event Table
 CREATE TABLE IF NOT EXISTS event (
@@ -32,6 +38,7 @@ first_seen INTEGER NOT NULL, -- when the event was first seen (not authored!) (s
 created_at INTEGER NOT NULL, -- when the event was authored
 author BLOB NOT NULL, -- author pubkey
 kind INTEGER NOT NULL, -- event kind
+hidden INTEGER, -- relevant for queries
 content TEXT NOT NULL -- serialized json of event object
 );
 
@@ -64,6 +71,45 @@ FOREIGN KEY(event_id) REFERENCES event(id) ON UPDATE RESTRICT ON DELETE CASCADE
 CREATE INDEX IF NOT EXISTS pubkey_ref_index ON pubkey_ref(referenced_pubkey);
 "##;
 
+/// Upgrade DB to latest version, and execute pragma settings
+pub fn upgrade_db(conn: &mut Connection) -> Result<()> {
+    // check the version.
+    let curr_version = db_version(conn)?;
+    info!("DB version = {:?}", curr_version);
+
+    // initialize from scratch
+    if curr_version == 0 {
+        match conn.execute_batch(INIT_SQL) {
+            Ok(()) => info!("database pragma/schema initialized to v2, and ready"),
+            Err(err) => {
+                error!("update failed: {}", err);
+                panic!("database could not be initialized");
+            }
+        }
+    } else if curr_version == 1 {
+        // only change is adding a hidden column to events.
+        let upgrade_sql = r##"
+ALTER TABLE event ADD hidden INTEGER;
+UPDATE event SET hidden=FALSE;
+PRAGMA user_version = 2;
+"##;
+        match conn.execute_batch(upgrade_sql) {
+            Ok(()) => info!("database schema upgraded v1 -> v2"),
+            Err(err) => {
+                error!("update failed: {}", err);
+                panic!("database could not be upgraded");
+            }
+        }
+    } else if curr_version == 2 {
+        debug!("Database version was already current");
+    } else if curr_version > 2 {
+        panic!("Database version is newer than supported by this executable");
+    }
+    // Setup PRAGMA
+    conn.execute_batch(STARTUP_SQL)?;
+    Ok(())
+}
+
 /// Spawn a database writer that persists events to the SQLite store.
 pub async fn db_writer(
     mut event_rx: tokio::sync::mpsc::Receiver<Event>,
@@ -75,12 +121,13 @@ pub async fn db_writer(
             OpenFlags::SQLITE_OPEN_READ_WRITE | OpenFlags::SQLITE_OPEN_CREATE,
         )?;
         info!("opened database for writing");
+        upgrade_db(&mut conn)?;
+        // if version is zero, then we need to initialize from scratch.
+        // if version is one, we need to upgrade.
+        // if version is two, we are at the latest!
+
         // TODO: determine if we need to execute the init script.
         // TODO: check database app id / version before proceeding.
-        match conn.execute_batch(INIT_SQL) {
-            Ok(()) => info!("database pragma/schema initialized and ready"),
-            Err(err) => error!("update failed: {}", err),
-        }
         loop {
             // call blocking read on channel
             let next_event = event_rx.blocking_recv();
@@ -110,6 +157,12 @@ pub async fn db_writer(
     })
 }
 
+pub fn db_version(conn: &mut Connection) -> Result<usize> {
+    let query = "PRAGMA user_version;";
+    let curr_version = conn.query_row(query, [], |row| row.get(0))?;
+    Ok(curr_version)
+}
+
 /// Persist an event to the database.
 pub fn write_event(conn: &mut Connection, e: &Event) -> Result<usize> {
     // start transaction
@@ -120,7 +173,7 @@ pub fn write_event(conn: &mut Connection, e: &Event) -> Result<usize> {
     let event_str = serde_json::to_string(&e).ok();
     // ignore if the event hash is a duplicate.
     let ins_count = tx.execute(
-        "INSERT OR IGNORE INTO event (event_hash, created_at, kind, author, content, first_seen) VALUES (?1, ?2, ?3, ?4, ?5, strftime('%s','now'));",
+        "INSERT OR IGNORE INTO event (event_hash, created_at, kind, author, content, first_seen, hidden) VALUES (?1, ?2, ?3, ?4, ?5, strftime('%s','now'), FALSE);",
         params![id_blob, e.created_at, e.kind, pubkey_blob, event_str]
     )?;
     if ins_count == 0 {
@@ -150,6 +203,17 @@ pub fn write_event(conn: &mut Connection, e: &Event) -> Result<usize> {
             )?;
         }
     }
+    // if this event is for a metadata update, hide every other kind=0
+    // event from the same author that was issued earlier
+    if e.kind == 0 {
+        let update_count = tx.execute(
+            "UPDATE event SET hidden=TRUE WHERE id!=? AND kind=0 AND author=? AND created_at <= ?",
+            params![ev_id, hex::decode(&e.pubkey).ok(), e.created_at],
+        )?;
+        if update_count > 0 {
+            info!("hid {} older metadata events", update_count);
+        }
+    }
     tx.commit()?;
     Ok(ins_count)
 }
@@ -242,8 +306,8 @@ fn query_from_sub(sub: &Subscription) -> String {
             fc.push_str(" )");
             filter_clauses.push(fc);
         } else {
-            // if there are no filter clauses, we should return everything
-            filter_clauses.push(" 1=1 ".to_owned());
+            // never display hidden events
+            filter_clauses.push("hidden!=FALSE".to_owned());
         }
     }