Added option to only run the compressor on a range of state groups in…

… a room (#44)

src/compressor.rs

@@ -141,6 +141,23 @@ impl<'a> Compressor<'a> {
         pb.enable_steady_tick(100);
 
         for (&state_group, entry) in self.original_state_map {
+            // Check whether this entry is in_range or is just present in the map due to being
+            // a predecessor of a group that IS in_range for compression
+            if !entry.in_range {
+                let new_entry = StateGroupEntry {
+                    // in_range is kept the same so that the new entry is equal to the old entry
+                    // otherwise it might trigger a useless database transaction
+                    in_range: entry.in_range,
+                    prev_state_group: entry.prev_state_group,
+                    state_map: entry.state_map.clone(),
+                };
+                // Paranoidly assert that not making changes to this entry
+                // could probably be removed...
+                assert!(new_entry == *entry);
+                self.new_state_group_map.insert(state_group, new_entry);
+
+                continue;
+            }
             let mut prev_state_group = None;
             for level in &mut self.levels {
                 if level.has_space() {
@@ -162,6 +179,7 @@ impl<'a> Compressor<'a> {
             self.new_state_group_map.insert(
                 state_group,
                 StateGroupEntry {
+                    in_range: true,
                     prev_state_group,
                     state_map: delta,
                 },
@@ -239,6 +257,7 @@ fn test_new_map() {
         initial.insert(
             i,
             StateGroupEntry {
+                in_range: true,
                 prev_state_group: prev,
                 state_map: StateMap::new(),
             },

src/database.rs

@@ -25,40 +25,62 @@ use super::StateGroupEntry;
 /// specific room.
 ///
 /// - Connects to the database
-/// - Fetches rows with group id lower than max
+/// - Fetches the first [group] rows with group id after [min]
 /// - Recursively searches for missing predecessors and adds those
 ///
+/// Returns with the state_group map and the id of the last group that was used
+///
 /// # Arguments
 ///
-/// * `room_id`         -   The ID of the room in the database
-/// * `db_url`          -   The URL of a Postgres database. This should be of the
-///                         form: "postgresql://user:pass@domain:port/database"
-/// * `max_state_group` -   If specified, then only fetch the entries for state
-///                         groups lower than or equal to this number. (N.B. all
-///                         predecessors are also fetched)
+/// * `room_id`             -   The ID of the room in the database
+/// * `db_url`              -   The URL of a Postgres database. This should be of the
+///                             form: "postgresql://user:pass@domain:port/database"
+/// * `min_state_group`     -   If specified, then only fetch the entries for state
+///                             groups greater than (but not equal) to this number. It
+///                             also requires groups_to_compress to be specified
+/// * 'groups_to_compress'  -   The number of groups to get from the database before stopping
+/// * `max_state_group`     -   If specified, then only fetch the entries for state
+///                             groups lower than or equal to this number.
 pub fn get_data_from_db(
     db_url: &str,
     room_id: &str,
+    min_state_group: Option<i64>,
+    groups_to_compress: Option<i64>,
     max_state_group: Option<i64>,
-) -> BTreeMap<i64, StateGroupEntry> {
+) -> (BTreeMap<i64, StateGroupEntry>, i64) {
+    // connect to the database
     let mut builder = SslConnector::builder(SslMethod::tls()).unwrap();
     builder.set_verify(SslVerifyMode::NONE);
     let connector = MakeTlsConnector::new(builder.build());
 
     let mut client = Client::connect(db_url, connector).unwrap();
 
-    let mut state_group_map = get_initial_data_from_db(&mut client, room_id, max_state_group);
+    // Search for the group id of the groups_to_compress'th group after min_state_group
+    // If this is saved, then the compressor can continue by having min_state_group being
+    // set to this maximum
+    let max_group_found = find_max_group(
+        &mut client,
+        room_id,
+        min_state_group,
+        groups_to_compress,
+        max_state_group,
+    );
+
+    let mut state_group_map =
+        get_initial_data_from_db(&mut client, room_id, min_state_group, max_group_found);
 
     println!("Got initial state from database. Checking for any missing state groups...");
 
     // Due to reasons some of the state groups appear in the edges table, but
-    // not in the state_groups_state table. This means they don't get included
-    // in our DB queries, so we have to fetch any missing groups explicitly.
+    // not in the state_groups_state table.
+    //
+    // Also it is likely that the predecessor of a node will not be within the
+    // chunk that was specified by min_state_group and groups_to_compress.
+    // This means they don't get included in our DB queries, so we have to fetch
+    // any missing groups explicitly.
+    //
     // Since the returned groups may themselves reference groups we don't have,
     // we need to do this recursively until we don't find any more missing.
-    //
-    // N.B. This does NOT currently fetch the deltas for the missing groups!
-    // By carefully chosen max_state_group this might cause issues...?
     loop {
         let mut missing_sgs: Vec<_> = state_group_map
             .iter()
@@ -76,41 +98,92 @@ pub fn get_data_from_db(
             .collect();
 
         if missing_sgs.is_empty() {
-            println!("No missing state groups");
+            // println!("No missing state groups");
             break;
         }
 
         missing_sgs.sort_unstable();
         missing_sgs.dedup();
 
-        println!("Missing {} state groups", missing_sgs.len());
+        // println!("Missing {} state groups", missing_sgs.len());
 
-        let map = get_missing_from_db(&mut client, &missing_sgs);
-        state_group_map.extend(map.into_iter());
+        // find state groups not picked up already and add them to the map
+        let map = get_missing_from_db(&mut client, &missing_sgs, min_state_group, max_group_found);
+        for (k, v) in map {
+            state_group_map.entry(k).or_insert(v);
+        }
     }
 
-    state_group_map
+    (state_group_map, max_group_found)
+}
+
+/// Returns the group ID of the last group to be compressed
+///
+/// This can be saved so that future runs of the compressor only
+/// continue from after this point
+///
+/// # Arguments
+///
+/// * `client`              -   A Postgres client to make requests with
+/// * `room_id`             -   The ID of the room in the database
+/// * `min_state_group`     -   The lower limit (non inclusive) of group id's to compress
+/// * 'groups_to_compress'  -   How many groups to compress
+/// * `max_state_group`     -   The upper bound on what this method can return
+fn find_max_group(
+    client: &mut Client,
+    room_id: &str,
+    min_state_group: Option<i64>,
+    groups_to_compress: Option<i64>,
+    max_state_group: Option<i64>,
+) -> i64 {
+    // Get list of state_id's in a certain room
+    let mut query_chunk_of_ids = "SELECT id FROM state_groups WHERE room_id = $1".to_string();
+    let params: Vec<&(dyn ToSql + Sync)>;
+
+    if let Some(max) = max_state_group {
+        query_chunk_of_ids = format!("{} AND id <= {}", query_chunk_of_ids, max)
+    }
+
+    // Adds additional constraint if a groups_to_compress has been specified
+    if min_state_group.is_some() && groups_to_compress.is_some() {
+        params = vec![&room_id, &min_state_group, &groups_to_compress];
+        query_chunk_of_ids = format!(r"{} AND id > $2 LIMIT $3", query_chunk_of_ids);
+    } else {
+        params = vec![&room_id];
+        query_chunk_of_ids = format!(r"{} ORDER BY id DESC LIMIT 1", query_chunk_of_ids);
+    }
+
+    let sql_query = format!(
+        "SELECT id FROM ({}) AS ids ORDER BY ids.id DESC LIMIT 1",
+        query_chunk_of_ids
+    );
+    let final_row = client.query(sql_query.as_str(), &params).unwrap();
+
+    final_row.last().unwrap().get(0)
 }
 
 /// Fetch the entries in state_groups_state and immediate predecessors for
 /// a specific room.
 ///
-/// - Fetches rows with group id lower than max
+/// - Fetches first [groups_to_compress] rows with group id higher than min
 /// - Stores the group id, predecessor id and deltas into a map
+/// - returns map and maximum row that was considered
 ///
 /// # Arguments
 ///
 /// * `client`          -   A Postgres client to make requests with
 /// * `room_id`         -   The ID of the room in the database
-/// * `max_state_group` -   If specified, then only fetch the entries for state
-///                         groups lower than or equal to this number. (N.B. doesn't
-///                         fetch IMMEDIATE predecessors if ID is above this number)
+/// * `min_state_group` -   If specified, then only fetch the entries for state
+///                         groups greater than (but not equal) to this number. It
+///                         also requires groups_to_compress to be specified
+/// * 'max_group_found' -   The upper limit on state_groups ids to get from the database
 fn get_initial_data_from_db(
     client: &mut Client,
     room_id: &str,
-    max_state_group: Option<i64>,
+    min_state_group: Option<i64>,
+    max_group_found: i64,
 ) -> BTreeMap<i64, StateGroupEntry> {
-    // Query to get id, predecessor and delta for each state group
+    // Query to get id, predecessor and deltas for each state group
     let sql = r#"
         SELECT m.id, prev_state_group, type, state_key, s.event_id
         FROM state_groups AS m
@@ -119,18 +192,21 @@ fn get_initial_data_from_db(
         WHERE m.room_id = $1
     "#;
 
-    // Adds additional constraint if a max_state_group has been specified
-    // Then sends query to the datatbase
-    let mut rows = if let Some(s) = max_state_group {
-        let params: Vec<&dyn ToSql> = vec![&room_id, &s];
-        client.query_raw(format!(r"{} AND m.id <= $2", sql).as_str(), params)
+    // Adds additional constraint if minimum state_group has been specified.
+    // note that the maximum group only affects queries if there is also a minimum
+    // otherwise it is assumed that ALL groups should be fetched
+    let mut rows = if let Some(min) = min_state_group {
+        let params: Vec<&dyn ToSql> = vec![&room_id, &min, &max_group_found];
+        client.query_raw(
+            format!(r"{} AND m.id > $2 AND m.id <= $3", sql).as_str(),
+            params,
+        )
     } else {
         client.query_raw(sql, &[room_id])
     }
     .unwrap();
 
     // Copy the data from the database into a map
-
     let mut state_group_map: BTreeMap<i64, StateGroupEntry> = BTreeMap::new();
 
     let pb = ProgressBar::new_spinner();
@@ -143,8 +219,10 @@ fn get_initial_data_from_db(
         // The row in the map to copy the data to
         let entry = state_group_map.entry(row.get(0)).or_default();
 
-        // Save the predecessor (this may already be there)
+        // Save the predecessor and mark for compression (this may already be there)
+        // TODO: slightly fewer redundant rewrites
         entry.prev_state_group = row.get(1);
+        entry.in_range = true;
 
         // Copy the single delta from the predecessor stored in this row
         if let Some(etype) = row.get::<_, Option<String>>(2) {
@@ -172,34 +250,57 @@ fn get_initial_data_from_db(
 ///
 /// * `client`          -   A Postgres client to make requests with
 /// * `missing_sgs`     -   An array of missing state_group ids
-fn get_missing_from_db(client: &mut Client, missing_sgs: &[i64]) -> BTreeMap<i64, StateGroupEntry> {
-    let mut rows = client
-        .query_raw(
-            r#"
-                SELECT state_group, prev_state_group
-                FROM state_group_edges
-                WHERE state_group = ANY($1)
-            "#,
-            &[missing_sgs],
-        )
-        .unwrap();
+/// * 'min_state_group' -   Minimum state_group id to mark as in range
+/// * 'max_group_found' -   Maximum state_group id to mark as in range
+fn get_missing_from_db(
+    client: &mut Client,
+    missing_sgs: &[i64],
+    min_state_group: Option<i64>,
+    max_group_found: i64,
+) -> BTreeMap<i64, StateGroupEntry> {
+    // "Due to reasons" it is possible that some states only appear in edges table and not in state_groups table
+    // so since we know the IDs we're looking for as they are the missing predecessors, we can find them by
+    // left joining onto the edges table (instead of the state_group table!)
+    let sql = r#"
+        SELECT target.prev_state_group, source.prev_state_group, state.type, state.state_key, state.event_id
+        FROM state_group_edges AS target
+        LEFT JOIN state_group_edges AS source ON (target.prev_state_group = source.state_group)
+        LEFT JOIN state_groups_state AS state ON (target.prev_state_group = state.state_group)
+        WHERE target.prev_state_group = ANY($1)
+    "#;
+
+    let mut rows = client.query_raw(sql, &[missing_sgs]).unwrap();
 
-    // initialise the map with empty entries (the missing group may not
-    // have a prev_state_group either)
-    let mut state_group_map: BTreeMap<i64, StateGroupEntry> = missing_sgs
-        .iter()
-        .map(|sg| (*sg, StateGroupEntry::default()))
-        .collect();
+    let mut state_group_map: BTreeMap<i64, StateGroupEntry> = BTreeMap::new();
 
     while let Some(row) = rows.next().unwrap() {
-        let state_group = row.get(0);
-        let entry = state_group_map.get_mut(&state_group).unwrap();
+        let id = row.get(0);
+        // The row in the map to copy the data to
+        let entry = state_group_map.entry(id).or_default();
+
+        // Save the predecessor and mark for compression (this may already be there)
+        // Also may well not exist!
         entry.prev_state_group = row.get(1);
+        if let Some(min) = min_state_group {
+            if min < id && id <= max_group_found {
+                entry.in_range = true
+            }
+        }
+
+        // Copy the single delta from the predecessor stored in this row
+        if let Some(etype) = row.get::<_, Option<String>>(2) {
+            entry.state_map.insert(
+                &etype,
+                &row.get::<_, String>(3),
+                row.get::<_, String>(4).into(),
+            );
+        }
     }
 
     state_group_map
 }
 
+// TODO: find a library that has an existing safe postgres escape function
 /// Helper function that escapes the wrapped text when writing SQL
 pub struct PGEscape<'a>(pub &'a str);
 

src/graphing.rs

@@ -57,15 +57,15 @@ fn output_csv(groups: &Graph, edges_output: &mut File, nodes_output: &mut File)
 /// * `after`       - A map from state group ids to StateGroupEntries
 ///                   the information from this map goes into after_edges.csv
 ///                   and after_nodes.csv
-pub fn make_graphs(before: Graph, after: Graph) {
+pub fn make_graphs(before: &Graph, after: &Graph) {
     // Open all the files to output to
     let mut before_edges_file = File::create("before_edges.csv").unwrap();
     let mut before_nodes_file = File::create("before_nodes.csv").unwrap();
     let mut after_edges_file = File::create("after_edges.csv").unwrap();
     let mut after_nodes_file = File::create("after_nodes.csv").unwrap();
 
     // Write before's information to before_edges and before_nodes
-    output_csv(&before, &mut before_edges_file, &mut before_nodes_file);
+    output_csv(before, &mut before_edges_file, &mut before_nodes_file);
     // Write afters's information to after_edges and after_nodes
-    output_csv(&after, &mut after_edges_file, &mut after_nodes_file);
+    output_csv(after, &mut after_edges_file, &mut after_nodes_file);
 }