Child storage tests and genesis fix. (#3185)

* Using child storage, (srml-support only), test failing .

* fix simple tests.

* Enumerable by requiring owned struct (previous form only allow
&'static).
Broken tests are from genesis init.

* implement for_child_keys_with_prefix

* indent

* clear_child_prefix fix.

* clear_child_prefix fix 2.

* fix for storage_impl, if/when allowing child and not child this could be
reverted.

* Fix lot of urlinked child genesis, still need to look upon actual
genesis srml module code.
Probably still a lot of broken code needing debugging.

* switch well_known_key to their associated module child trie.
Fix a genesis init (balance).
Complete some testing.
Comment some tests before using.

* fixing test runtime child keys

* latest commit fix broken genesis init

* fix system balances child name.

* Important fix: storage_root from test externalities need children (it is
already the case for ext).

* executive root with child calculation

* Avoid empty trie on test ext.

* Symetric removal of key for system.

* commenting changes related tests.

* Remove child module specifics.

* fix issues.

* fix some formatting

* fix bench and bump runtime

* Remove extend_storage_overlays, assimilate_storage do the same as is
proper considering srml macro.

* Fix warning for assimilate.

* Removing kill as they do not impact any test cases.

* Use tuple of storage map instead of two parameters. This changes the
behavior of decl_storage genesis build closure (breaking api).

* Do not use build storage before assimilate.

* fix error

* Update core/state-machine/src/backend.rs

substrate/core/sr-io/src/lib.rs

@@ -141,6 +141,9 @@ export_api! {
 		/// Clear the storage entries with a key that starts with the given prefix.
 		fn clear_prefix(prefix: &[u8]);
 
+		/// Clear the child storage entries with a key that starts with the given prefix.
+		fn clear_child_prefix(storage_key: &[u8], prefix: &[u8]);
+
 		/// "Commit" all existing operations and compute the resultant storage root.
 		fn storage_root() -> [u8; 32];
 
@@ -401,7 +404,7 @@ mod imp {
 
 #[cfg(feature = "std")]
 pub use self::imp::{
-	StorageOverlay, ChildrenStorageOverlay, with_storage, with_storage_and_children,
+	StorageOverlay, ChildrenStorageOverlay, with_storage,
 	with_externalities
 };
 #[cfg(not(feature = "std"))]

substrate/core/sr-io/with_std.rs

@@ -141,6 +141,13 @@ impl StorageApi for () {
 		);
 	}
 
+	fn clear_child_prefix(storage_key: &[u8], prefix: &[u8]) {
+		ext::with(|ext| {
+			let storage_key = child_storage_key_or_panic(storage_key);
+			ext.clear_child_prefix(storage_key, prefix)
+		});
+	}
+
 	fn storage_root() -> [u8; 32] {
 		ext::with(|ext|
 			ext.storage_root()
@@ -455,36 +462,20 @@ pub type StorageOverlay = HashMap<Vec<u8>, Vec<u8>>;
 /// A set of key value pairs for children storage;
 pub type ChildrenStorageOverlay = HashMap<Vec<u8>, StorageOverlay>;
 
-/// Execute the given closure with global functions available whose functionality routes into
-/// externalities that draw from and populate `storage`. Forwards the value that the closure returns.
-pub fn with_storage<R, F: FnOnce() -> R>(storage: &mut StorageOverlay, f: F) -> R {
-	let mut alt_storage = Default::default();
-	rstd::mem::swap(&mut alt_storage, storage);
-	let mut ext = BasicExternalities::new(alt_storage);
-	let r = ext::using(&mut ext, f);
-	*storage = ext.into_storages().0;
-	r
-}
-
 /// Execute the given closure with global functions available whose functionality routes into
 /// externalities that draw from and populate `storage` and `children_storage`.
 /// Forwards the value that the closure returns.
-pub fn with_storage_and_children<R, F: FnOnce() -> R>(
-	storage: &mut StorageOverlay,
-	children_storage: &mut ChildrenStorageOverlay,
+pub fn with_storage<R, F: FnOnce() -> R>(
+	storage: &mut (StorageOverlay, ChildrenStorageOverlay),
 	f: F
 ) -> R {
 	let mut alt_storage = Default::default();
-	let mut alt_children_storage = Default::default();
 	rstd::mem::swap(&mut alt_storage, storage);
-	rstd::mem::swap(&mut alt_children_storage, children_storage);
 
-	let mut ext = BasicExternalities::new_with_children(alt_storage, alt_children_storage);
+	let mut ext = BasicExternalities::new(alt_storage.0, alt_storage.1);
 	let r = ext::using(&mut ext, f);
 
-	let storage_tuple = ext.into_storages();
-	*storage = storage_tuple.0;
-	*children_storage = storage_tuple.1;
+	*storage = ext.into_storages();
 
 	r
 }
@@ -524,7 +515,7 @@ mod std_tests {
 			true
 		}));
 
-		t = BasicExternalities::new(map![b"foo".to_vec() => b"bar".to_vec()]);
+		t = BasicExternalities::new(map![b"foo".to_vec() => b"bar".to_vec()], map![]);
 
 		assert!(!with_externalities(&mut t, || {
 			assert_eq!(storage(b"hello"), None);
@@ -537,7 +528,7 @@ mod std_tests {
 	fn read_storage_works() {
 		let mut t = BasicExternalities::new(map![
 			b":test".to_vec() => b"\x0b\0\0\0Hello world".to_vec()
-		]);
+		], map![]);
 
 		with_externalities(&mut t, || {
 			let mut v = [0u8; 4];
@@ -556,7 +547,7 @@ mod std_tests {
 			b":abcd".to_vec() => b"\x0b\0\0\0Hello world".to_vec(),
 			b":abc".to_vec() => b"\x0b\0\0\0Hello world".to_vec(),
 			b":abdd".to_vec() => b"\x0b\0\0\0Hello world".to_vec()
-		]);
+		], map![]);
 
 		with_externalities(&mut t, || {
 			clear_prefix(b":abc");

substrate/core/sr-io/without_std.rs

@@ -213,6 +213,13 @@ pub mod ext {
 		fn ext_exists_storage(key_data: *const u8, key_len: u32) -> u32;
 		/// Remove storage entries which key starts with given prefix.
 		fn ext_clear_prefix(prefix_data: *const u8, prefix_len: u32);
+		/// Remove child storage entries which key starts with given prefix.
+		fn ext_clear_child_prefix(
+			storage_key_data: *const u8,
+			storage_key_len: u32,
+			prefix_data: *const u8,
+			prefix_len: u32
+		);
 		/// Gets the value of the given key from storage.
 		///
 		/// The host allocates the memory for storing the value.
@@ -703,6 +710,15 @@ impl StorageApi for () {
 		}
 	}
 
+	fn clear_child_prefix(storage_key: &[u8], prefix: &[u8]) {
+		unsafe {
+			ext_clear_child_prefix.get()(
+				storage_key.as_ptr(), storage_key.len() as u32,
+				prefix.as_ptr(), prefix.len() as u32
+			);
+		}
+	}
+
 	fn kill_child_storage(storage_key: &[u8]) {
 		unsafe {
 			ext_kill_child_storage.get()(