Populate changeset of attributes inside TxReport during transact.

Batch up TxReports for entire transaction.
Notify observers about committed transaction.
Store transaction observer service inside Conn

db/src/tx.rs

@@ -51,8 +51,9 @@ use std::collections::{
     BTreeSet,
     VecDeque,
 };
-
-use std::rc::Rc;
+use std::rc::{
+    Rc,
+};
 
 use db;
 use db::{
@@ -106,6 +107,7 @@ use schema::{
 };
 use types::{
     Attribute,
+    AttributeSet,
     AVPair,
     AVMap,
     Entid,
@@ -527,8 +529,7 @@ impl<'conn, 'a, W> Tx<'conn, 'a, W> where W: TransactWatcher {
     /// This approach is explained in https://github.com/mozilla/mentat/wiki/Transacting.
     // TODO: move this to the transactor layer.
     pub fn transact_entities<I>(&mut self, entities: I) -> Result<TxReport>
-    where I: IntoIterator<Item=Entity>,
-          W: TransactWatcher {
+    where I: IntoIterator<Item=Entity> {
         // Pipeline stage 1: entities -> terms with tempids and lookup refs.
         let (terms_with_temp_ids_and_lookup_refs, tempid_set, lookup_ref_set) = self.entities_into_terms_with_temp_ids_and_lookup_refs(entities)?;
 
@@ -542,8 +543,7 @@ impl<'conn, 'a, W> Tx<'conn, 'a, W> where W: TransactWatcher {
     }
 
     pub fn transact_simple_terms<I>(&mut self, terms: I, tempid_set: InternSet<TempId>) -> Result<TxReport>
-    where I: IntoIterator<Item=TermWithTempIds>,
-          W: TransactWatcher {
+    where I: IntoIterator<Item=TermWithTempIds> {
         // TODO: push these into an internal transaction report?
         let mut tempids: BTreeMap<TempId, KnownEntid> = BTreeMap::default();
 
@@ -614,7 +614,9 @@ impl<'conn, 'a, W> Tx<'conn, 'a, W> where W: TransactWatcher {
                                                     final_populations.allocated,
                                                     inert_terms.into_iter().map(|term| term.unwrap()).collect()].concat();
 
+
         let tx_instant;
+        let mut affected_attrs = AttributeSet::new();
 
         { // TODO: Don't use this block to scope borrowing the schema; instead, extract a helper function.
 
@@ -669,6 +671,7 @@ impl<'conn, 'a, W> Tx<'conn, 'a, W> where W: TransactWatcher {
                     }
 
                     self.watcher.datom(op, e, a, &v);
+                    affected_attrs.insert(a);
 
                     let reduced = (e, a, attribute, v, added);
                     match (attribute.fulltext, attribute.multival) {
@@ -735,6 +738,7 @@ impl<'conn, 'a, W> Tx<'conn, 'a, W> where W: TransactWatcher {
             tx_id: self.tx_id,
             tx_instant,
             tempids: tempids,
+            changeset: affected_attrs,
         })
     }
 }

src/conn.rs

@@ -57,6 +57,7 @@ use mentat_db::{
     transact,
     transact_terms,
     PartitionMap,
+    TxObservationService,
     TxReport,
 };
 
@@ -140,6 +141,7 @@ pub struct Conn {
 
     // TODO: maintain cache of query plans that could be shared across threads and invalidated when
     // the schema changes. #315.
+    tx_observer_service: Mutex<TxObservationService>,
 }
 
 /// A convenience wrapper around a single SQLite connection and a Conn. This is suitable
@@ -209,10 +211,10 @@ pub struct InProgress<'a, 'c> {
     generation: u64,
     partition_map: PartitionMap,
     schema: Schema,
-
     cache: InProgressSQLiteAttributeCache,
-
     use_caching: bool,
+    tx_reports: Vec<TxReport>,
+    observer_service: Option<&'a Mutex<TxObservationService>>,
 }
 
 /// Represents an in-progress set of reads to the store. Just like `InProgress`,
@@ -381,6 +383,7 @@ impl<'a, 'c> InProgress<'a, 'c> {
                            self.cache.transact_watcher(),
                            terms,
                            tempid_set)?;
+        self.tx_reports.push(report.clone());
         self.partition_map = next_partition_map;
         if let Some(schema) = next_schema {
             self.schema = schema;
@@ -404,6 +407,8 @@ impl<'a, 'c> InProgress<'a, 'c> {
                      &self.schema,
                      self.cache.transact_watcher(),
                      entities)?;
+        self.tx_reports.push(report.clone());
+
         self.partition_map = next_partition_map;
         if let Some(schema) = next_schema {
             self.schema = schema;
@@ -447,6 +452,12 @@ impl<'a, 'c> InProgress<'a, 'c> {
         metadata.generation += 1;
         metadata.partition_map = self.partition_map;
 
+        // let the transaction observer know that there have been some transactions committed.
+        if let Some(ref observer_service) = self.observer_service {
+            let mut os = observer_service.lock().unwrap();
+            os.transaction_did_commit(self.tx_reports);
+        }
+
         // Update the conn's cache if we made any changes.
         self.cache.commit_to(&mut metadata.attribute_cache);
 
@@ -458,6 +469,12 @@ impl<'a, 'c> InProgress<'a, 'c> {
             // TODO: consider making vocabulary lookup lazy -- we won't need it much of the time.
         }
 
+        // run any commands that we've created along the way.
+        if let Some(ref observer_service) = self.observer_service {
+            let mut os = observer_service.lock().unwrap();
+            os.run();
+        }
+
         Ok(())
     }
 
@@ -571,6 +588,7 @@ impl Conn {
     fn new(partition_map: PartitionMap, schema: Schema) -> Conn {
         Conn {
             metadata: Mutex::new(Metadata::new(0, partition_map, Arc::new(schema), Default::default())),
+            tx_observer_service: Mutex::new(TxObservationService::new()),
         }
     }
 
@@ -712,6 +730,8 @@ impl Conn {
             schema: (*current_schema).clone(),
             cache: InProgressSQLiteAttributeCache::from_cache(cache_cow),
             use_caching: true,
+            tx_reports: Vec::new(),
+            observer_service: if self.tx_observer_service.lock().unwrap().has_observers() { Some(&self.tx_observer_service) } else { None },
         })
     }