Add documentation for db setup and more frequent save

crates/lox-distributor/README.md

@@ -1,12 +1,11 @@
 # Lox Distributor
 
 The Lox distributor receives resources from [rdsys](https://gitlab.torproject.org/tpo/anti-censorship/rdsys) and writes them to [Lox
-BridgeLines](https://git-crysp.uwaterloo.ca/iang/lox/src/master/src/bridge_table.rs#L42). Concurrently, it receives and responds to requests from [Lox clients](https://gitlab.torproject.org/tpo/anti-censorship/lox/lox-wasm). 
-
+BridgeLines](https://git-crysp.uwaterloo.ca/iang/lox/src/master/src/bridge_table.rs#L42). Concurrently, it receives and responds to requests from [Lox clients](https://gitlab.torproject.org/tpo/anti-censorship/lox/lox-wasm). It saves the [LoxContext](https://gitlab.torproject.org/tpo/anti-censorship/lox-rs/-/blob/main/crates/lox-distributor/src/lox_context.rs) to a database every time the Lox bridgetable is updated and before the distributor is shutdown.
 ## Configure rdsys stream
 
 A test `config.json` is included for testing on a local instance of rdsys. This
-can be edited to correspond to the desired types of resources and endpoints.
+can be edited to correspond to the desired types of resources, endpoints and database configuration.
 
 ## Test Run
 
@@ -26,6 +25,13 @@ Finally run rdsys:
  ./backend --config config.json
 ```
 
+## Database Config
+
+The database has a few configuration options. The path for where the database
+should be read/written can be specified in the `config.json`. Rolling back to a
+previous version of the database is also possible by passing the
+`roll_back_date` flag at runtime and providing the date/time as a `%Y-%m-%d_%H:%M:%S` string. This argument should be passed if the `LoxContext` should be rolled back to a previous state due to, for example, a mass blocking event that is likely not due to Lox user behaviour. If the exact roll back date/time is not known, the last db entry within 24 hours from the passed `roll_back_date` will be used or else the program will fail gracefully.
+
 ### Run Lox Distributor locally
 
 Simply run `cargo run -- config.json` :)

crates/lox-distributor/src/main.rs

@@ -311,9 +311,11 @@ async fn context_manager(
                 if let Err(e) = sender.send(response) {
                     eprintln!("Server Response Error: {:?}", e);
                 };
+                lox_db.write_context(context.clone());
                 sleep(Duration::from_millis(1)).await;
             }
             Shutdown { shutdown_sig } => {
+                lox_db.write_context(context.clone());
                 println!("Sending Shutdown Signal, all threads should shutdown.");
                 drop(shutdown_sig);
                 println!("Shutdown Sent.");