Adaptive heap size (#328)

* heap-size is a CLI arg, make it 512 by default

* Fix tests

* Adaptive heap size.

* Allow storage_exists

substrate/polkadot/cli/src/cli.yml

@@ -99,6 +99,14 @@ args:
       long: execution
       value_name: STRATEGY
       help: The means of execution used when calling into the runtime. Can be either wasm, native or both.
+  - min-heap-pages:
+      long: min-heap-pages
+      value_name: COUNT
+      help: The number of 64KB pages to allocate for Wasm execution initially.
+  - max-heap-pages:
+      long: max-heap-pages
+      value_name: COUNT
+      help: The maximum number of 64KB pages to ever allocate for Wasm execution. Don't alter this unless you know what you're doing.
 subcommands:
   - build-spec:
       about: Build a spec.json file, outputing to stdout
@@ -162,3 +170,15 @@ subcommands:
               value_name: PATH
               help: Specify custom base path.
               takes_value: true
+          - execution:
+              long: execution
+              value_name: STRATEGY
+              help: The means of execution used when calling into the runtime. Can be either wasm, native or both.
+          - min-heap-pages:
+              long: min-heap-pages
+              value_name: COUNT
+              help: The number of 64KB pages to allocate for Wasm execution initially.
+          - max-heap-pages:
+              long: max-heap-pages
+              value_name: COUNT
+              help: The maximum number of 64KB pages to ever allocate for Wasm execution. Don't alter this unless you know what you're doing.

substrate/polkadot/cli/src/lib.rs

@@ -237,6 +237,13 @@ pub fn run<I, T, W>(args: I, worker: W) -> error::Result<()> where
 			service::Roles::FULL
 		};
 
+	if let Some(v) = matches.value_of("min-heap-pages") {
+		config.min_heap_pages = v.parse().map_err(|_| "Invalid --min-heap-pages argument")?;
+	}
+	if let Some(v) = matches.value_of("max-heap-pages") {
+		config.max_heap_pages = v.parse().map_err(|_| "Invalid --max-heap-pages argument")?;
+	}
+
 	if let Some(s) = matches.value_of("execution") {
 		config.execution_strategy = match s {
 			"both" => service::ExecutionStrategy::Both,
@@ -393,6 +400,23 @@ fn import_blocks<E>(matches: &clap::ArgMatches, exit: E) -> error::Result<()>
 	let base_path = base_path(matches);
 	let mut config = service::Configuration::default_with_spec(spec);
 	config.database_path = db_path(&base_path, config.chain_spec.id()).to_string_lossy().into();
+
+	if let Some(v) = matches.value_of("min-heap-pages") {
+		config.min_heap_pages = v.parse().map_err(|_| "Invalid --min-heap-pages argument")?;
+	}
+	if let Some(v) = matches.value_of("max-heap-pages") {
+		config.max_heap_pages = v.parse().map_err(|_| "Invalid --max-heap-pages argument")?;
+	}
+
+	if let Some(s) = matches.value_of("execution") {
+		config.execution_strategy = match s {
+			"both" => service::ExecutionStrategy::Both,
+			"native" => service::ExecutionStrategy::NativeWhenPossible,
+			"wasm" => service::ExecutionStrategy::AlwaysWasm,
+			_ => return Err(error::ErrorKind::Input("Invalid execution mode specified".to_owned()).into()),
+		};
+	}
+
 	let client = service::new_client(config)?;
 	let (exit_send, exit_recv) = std::sync::mpsc::channel();