Feature to use unbounded weights

CHANGELOG.md

@@ -10,6 +10,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
   DDlog, which will crash DDlog programs at runtime if they overflow the
   weights attached to data values.  This may be preferable to generating
   incorrect results.
+- Rust compilation option `unbounded_weights` for the code generated by
+  DDlog which will never crash DDlog programs at runtime but may be slower.
 
 ## [0.48.2] - Sep 13, 2021
 

doc/tutorial/tutorial.md

@@ -3797,12 +3797,19 @@ Weight overflow in turns leads to silent wrong results at runtime [bug
 878](https://github.com/vmware/differential-datalog/issues/878).
 
 To mitigate this problem, the generated Rust code can be compiled with
-the a feature named `checked_weights`.  This causes programs that
+a feature named `checked_weights`.  This causes programs that
 overflow the weights to crash with a Rust `panic` at runtime instead
 of producing incorrect results.  This can be done e.g., by compiling
 the result produced by the ddlog compiler with a command line like
 `cargo build --release --features=checked_weights`.
 
+Alternatively, the generated Rust code can be compiled with a feature
+named `unbounded_weights`.  This may cause the program to execute
+slower and use more memory, but the program will never produce
+incorrect results.  This can be done e.g., by compiling
+the result produced by the ddlog compiler with a command line like
+`cargo build --release --features=unbounded_weights`.
+
 ## Profiling
 
 DDlog's profiling features are designed to help the programmer identify

lib/ddlog_std.rs

@@ -1264,7 +1264,7 @@ impl<K: Clone, V: Clone> Clone for Group<K, V> {
                 key: key.clone(),
                 group: group
                     .iter()
-                    .map(|(v, w)| tuple2(project(v).clone(), i64::from(*w) as DDWeight))
+                    .map(|(v, w)| tuple2(project(v).clone(), i64::from(w.clone()) as DDWeight))
                     .collect(),
             },
             GroupEnum::ByVal { key, group } => GroupEnum::ByVal {
@@ -1435,7 +1435,7 @@ impl<'a, V: Clone> Iterator for GroupIter<'a, V> {
         match self {
             GroupIter::ByRef { iter, project } => match iter.next() {
                 None => None,
-                Some((x, w)) => Some(tuple2(project(x).clone(), i64::from(*w) as DDWeight)),
+                Some((x, w)) => Some(tuple2(project(x).clone(), i64::from(w.clone()) as DDWeight)),
             },
             GroupIter::ByVal { iter } => match iter.next() {
                 None => None,
@@ -1531,7 +1531,7 @@ impl<V: Clone> Iterator for GroupIntoIter<V> {
         match self {
             GroupIntoIter::ByRef { iter, project } => match iter.next() {
                 None => None,
-                Some((x, w)) => Some(tuple2(project(x).clone(), i64::from(*w) as DDWeight)),
+                Some((x, w)) => Some(tuple2(project(x).clone(), i64::from(w.clone()) as DDWeight)),
             },
             GroupIntoIter::ByVal { iter } => match iter.next() {
                 None => None,

rust/ddlog_benches/Cargo.toml

@@ -5,10 +5,9 @@ edition = "2018"
 license = "MIT"
 
 [features]
-# Use the following to run with checked_weights: 
-# panic on weight overflow.
-#default = ["benchmarks_ddlog/checked_weights"]
 default = []
+checked_weights = ["benchmarks_ddlog/checked_weights"]
+unbounded_weights = ["benchmarks_ddlog/unbounded_weights"]
 
 [dependencies]
 criterion = "0.3.3"

rust/ddlog_benches/Makefile.toml

@@ -5,19 +5,19 @@ dependencies = ["bench-twitter", "bench-livejournal"]
 # Runs the benchmark suite on the citations dataset
 [tasks.bench-livejournal]
 command = "cargo"
-args = ["bench", "LiveJournal", "--bench", "live_journal"]
+args = ["bench", "LiveJournal", "--bench", "live_journal", "${@}"]
 dependencies = ["build-ddlog", "download-livejournal"]
 
 # Runs the benchmark suite on the twitter dataset
 [tasks.bench-twitter]
 command = "cargo"
-args = ["bench", "--bench", "twitter"]
+args = ["bench", "--bench", "twitter", "${@}"]
 dependencies = ["build-ddlog", "download-twitter"]
 
 # Run twitter microbenchmarks only
 [tasks.bench-twitter-micro]
 command = "cargo"
-args = ["bench", "twitter-micro", "--bench", "twitter"]
+args = ["bench", "twitter-micro", "--bench", "twitter", "${@}"]
 dependencies = ["build-ddlog", "download-twitter"]
 
 # Runs `ddlog` to generate ddlog code

rust/ddlog_benches/README.md

@@ -30,3 +30,19 @@ For info on writing benchmarks see the [criterion user guide] and the [criterion
 [`cargo-make`]: https://github.com/sagiegurari/cargo-make
 [criterion user guide]: https://bheisler.github.io/criterion.rs/book/index.html
 [criterion docs]: https://docs.rs/criterion
+
+### Supported features
+
+The benchmarks can be run using checked_weights, which will cause a
+Rust panic on weight overflow.  This can be done by running:
+
+```sh
+cargo make benchmarks --features checked_weights
+```
+
+The benchmarks can be run using unbounded_weights, which will always
+produce correct results, but may run slower.  This can be done by running:
+
+```sh
+cargo make benchmarks --features unbounded_weights
+```

rust/template/Cargo.toml

@@ -14,6 +14,7 @@ command-line = ["cmd_parser", "rustop"]
 nested_ts_32 = ["differential_datalog/nested_ts_32"]
 c_api = ["differential_datalog/c_api"]
 checked_weights = ["differential_datalog/checked_weights"]
+unbounded_weights = ["differential_datalog/unbounded_weights"]
 
 [dependencies]
 abomonation = "0.7"

rust/template/differential_datalog/Cargo.toml

@@ -11,6 +11,8 @@ nested_ts_32 = []
 c_api = []
 # panic on weight overflow
 checked_weights = []
+# unbounded weights make the program slower but correct
+unbounded_weights = []
 
 [dependencies]
 #differential-dataflow = "0.11.0"

rust/template/differential_datalog/src/api/update_handler.rs

@@ -440,8 +440,10 @@ impl MTUpdateHandler for MTChainedUpdateHandler {
             self.handlers.iter().map(|h| h.mt_update_cb()).collect();
 
         Arc::new(move |relid, v, w| {
+            // not all weight implementations support copy
+            #[allow(clippy::clone_on_copy)]
             for cb in cbs.iter() {
-                cb(relid, v, w);
+                cb(relid, v, w.clone());
             }
         })
     }