1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
// This file is part of Substrate.

// Copyright (C) 2017-2022 Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// 	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#![cfg_attr(not(feature = "std"), no_std)]

//! Substrate externalities abstraction
//!
//! The externalities mainly provide access to storage and to registered extensions. Extensions
//! are for example the keystore or the offchain externalities. These externalities are used to
//! access the node from the runtime via the runtime interfaces.
//!
//! This crate exposes the main [`Externalities`] trait.

use sp_std::{
	any::{Any, TypeId},
	boxed::Box,
	vec::Vec,
};

use sp_storage::{ChildInfo, StateVersion, TrackedStorageKey};

pub use extensions::{Extension, ExtensionStore, Extensions};
pub use scope_limited::{set_and_run_with_externalities, with_externalities};

mod extensions;
mod scope_limited;

/// Externalities error.
#[derive(Debug)]
pub enum Error {
	/// Same extension cannot be registered twice.
	ExtensionAlreadyRegistered,
	/// Extensions are not supported.
	ExtensionsAreNotSupported,
	/// Extension `TypeId` is not registered.
	ExtensionIsNotRegistered(TypeId),
	/// Failed to update storage,
	StorageUpdateFailed(&'static str),
}

/// Results concerning an operation to remove many keys.
#[derive(codec::Encode, codec::Decode)]
#[must_use]
pub struct MultiRemovalResults {
	/// A continuation cursor which, if `Some` must be provided to the subsequent removal call.
	/// If `None` then all removals are complete and no further calls are needed.
	pub maybe_cursor: Option<Vec<u8>>,
	/// The number of items removed from the backend database.
	pub backend: u32,
	/// The number of unique keys removed, taking into account both the backend and the overlay.
	pub unique: u32,
	/// The number of iterations (each requiring a storage seek/read) which were done.
	pub loops: u32,
}

impl MultiRemovalResults {
	/// Deconstruct into the internal components.
	///
	/// Returns `(maybe_cursor, backend, unique, loops)`.
	pub fn deconstruct(self) -> (Option<Vec<u8>>, u32, u32, u32) {
		(self.maybe_cursor, self.backend, self.unique, self.loops)
	}
}

/// The Substrate externalities.
///
/// Provides access to the storage and to other registered extensions.
pub trait Externalities: ExtensionStore {
	/// Write a key value pair to the offchain storage database.
	fn set_offchain_storage(&mut self, key: &[u8], value: Option<&[u8]>);

	/// Read runtime storage.
	fn storage(&self, key: &[u8]) -> Option<Vec<u8>>;

	/// Get storage value hash.
	///
	/// This may be optimized for large values.
	fn storage_hash(&self, key: &[u8]) -> Option<Vec<u8>>;

	/// Get child storage value hash.
	///
	/// This may be optimized for large values.
	///
	/// Returns an `Option` that holds the SCALE encoded hash.
	fn child_storage_hash(&self, child_info: &ChildInfo, key: &[u8]) -> Option<Vec<u8>>;

	/// Read child runtime storage.
	///
	/// Returns an `Option` that holds the SCALE encoded hash.
	fn child_storage(&self, child_info: &ChildInfo, key: &[u8]) -> Option<Vec<u8>>;

	/// Set storage entry `key` of current contract being called (effective immediately).
	fn set_storage(&mut self, key: Vec<u8>, value: Vec<u8>) {
		self.place_storage(key, Some(value));
	}

	/// Set child storage entry `key` of current contract being called (effective immediately).
	fn set_child_storage(&mut self, child_info: &ChildInfo, key: Vec<u8>, value: Vec<u8>) {
		self.place_child_storage(child_info, key, Some(value))
	}

	/// Clear a storage entry (`key`) of current contract being called (effective immediately).
	fn clear_storage(&mut self, key: &[u8]) {
		self.place_storage(key.to_vec(), None);
	}

	/// Clear a child storage entry (`key`) of current contract being called (effective
	/// immediately).
	fn clear_child_storage(&mut self, child_info: &ChildInfo, key: &[u8]) {
		self.place_child_storage(child_info, key.to_vec(), None)
	}

	/// Whether a storage entry exists.
	fn exists_storage(&self, key: &[u8]) -> bool {
		self.storage(key).is_some()
	}

	/// Whether a child storage entry exists.
	fn exists_child_storage(&self, child_info: &ChildInfo, key: &[u8]) -> bool {
		self.child_storage(child_info, key).is_some()
	}

	/// Returns the key immediately following the given key, if it exists.
	fn next_storage_key(&self, key: &[u8]) -> Option<Vec<u8>>;

	/// Returns the key immediately following the given key, if it exists, in child storage.
	fn next_child_storage_key(&self, child_info: &ChildInfo, key: &[u8]) -> Option<Vec<u8>>;

	/// Clear an entire child storage.
	///
	/// Deletes all keys from the overlay and up to `maybe_limit` keys from the backend. No
	/// limit is applied if `maybe_limit` is `None`. Returns the cursor for the next call as `Some`
	/// if the child trie deletion operation is incomplete. In this case, it should be passed into
	/// the next call to avoid unaccounted iterations on the backend. Returns also the the number
	/// of keys that were removed from the backend, the number of unique keys removed in total
	/// (including from the overlay) and the number of backend iterations done.
	///
	/// As long as `maybe_cursor` is passed from the result of the previous call, then the number of
	/// iterations done will only ever be one more than the number of keys removed.
	///
	/// # Note
	///
	/// An implementation is free to delete more keys than the specified limit as long as
	/// it is able to do that in constant time.
	fn kill_child_storage(
		&mut self,
		child_info: &ChildInfo,
		maybe_limit: Option<u32>,
		maybe_cursor: Option<&[u8]>,
	) -> MultiRemovalResults;

	/// Clear storage entries which keys are start with the given prefix.
	///
	/// `maybe_limit`, `maybe_cursor` and result works as for `kill_child_storage`.
	fn clear_prefix(
		&mut self,
		prefix: &[u8],
		maybe_limit: Option<u32>,
		maybe_cursor: Option<&[u8]>,
	) -> MultiRemovalResults;

	/// Clear child storage entries which keys are start with the given prefix.
	///
	/// `maybe_limit`, `maybe_cursor` and result works as for `kill_child_storage`.
	fn clear_child_prefix(
		&mut self,
		child_info: &ChildInfo,
		prefix: &[u8],
		maybe_limit: Option<u32>,
		maybe_cursor: Option<&[u8]>,
	) -> MultiRemovalResults;

	/// Set or clear a storage entry (`key`) of current contract being called (effective
	/// immediately).
	fn place_storage(&mut self, key: Vec<u8>, value: Option<Vec<u8>>);

	/// Set or clear a child storage entry.
	fn place_child_storage(&mut self, child_info: &ChildInfo, key: Vec<u8>, value: Option<Vec<u8>>);

	/// Get the trie root of the current storage map.
	///
	/// This will also update all child storage keys in the top-level storage map.
	///
	/// The returned hash is defined by the `Block` and is SCALE encoded.
	fn storage_root(&mut self, state_version: StateVersion) -> Vec<u8>;

	/// Get the trie root of a child storage map.
	///
	/// This will also update the value of the child storage keys in the top-level storage map.
	///
	/// If the storage root equals the default hash as defined by the trie, the key in the top-level
	/// storage map will be removed.
	fn child_storage_root(
		&mut self,
		child_info: &ChildInfo,
		state_version: StateVersion,
	) -> Vec<u8>;

	/// Append storage item.
	///
	/// This assumes specific format of the storage item. Also there is no way to undo this
	/// operation.
	fn storage_append(&mut self, key: Vec<u8>, value: Vec<u8>);

	/// Start a new nested transaction.
	///
	/// This allows to either commit or roll back all changes made after this call to the
	/// top changes or the default child changes. For every transaction there cam be a
	/// matching call to either `storage_rollback_transaction` or `storage_commit_transaction`.
	/// Any transactions that are still open after returning from runtime are committed
	/// automatically.
	///
	/// Changes made without any open transaction are committed immediately.
	fn storage_start_transaction(&mut self);

	/// Rollback the last transaction started by `storage_start_transaction`.
	///
	/// Any changes made during that storage transaction are discarded. Returns an error when
	/// no transaction is open that can be closed.
	fn storage_rollback_transaction(&mut self) -> Result<(), ()>;

	/// Commit the last transaction started by `storage_start_transaction`.
	///
	/// Any changes made during that storage transaction are committed. Returns an error when
	/// no transaction is open that can be closed.
	fn storage_commit_transaction(&mut self) -> Result<(), ()>;

	/// Index specified transaction slice and store it.
	fn storage_index_transaction(&mut self, _index: u32, _hash: &[u8], _size: u32) {
		unimplemented!("storage_index_transaction");
	}

	/// Renew existing piece of transaction storage.
	fn storage_renew_transaction_index(&mut self, _index: u32, _hash: &[u8]) {
		unimplemented!("storage_renew_transaction_index");
	}

	/// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	/// Benchmarking related functionality and shouldn't be used anywhere else!
	/// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	///
	/// Wipes all changes from caches and the database.
	///
	/// The state will be reset to genesis.
	fn wipe(&mut self);

	/// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	/// Benchmarking related functionality and shouldn't be used anywhere else!
	/// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	///
	/// Commits all changes to the database and clears all caches.
	fn commit(&mut self);

	/// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	/// Benchmarking related functionality and shouldn't be used anywhere else!
	/// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	///
	/// Gets the current read/write count for the benchmarking process.
	fn read_write_count(&self) -> (u32, u32, u32, u32);

	/// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	/// Benchmarking related functionality and shouldn't be used anywhere else!
	/// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	///
	/// Resets read/write count for the benchmarking process.
	fn reset_read_write_count(&mut self);

	/// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	/// Benchmarking related functionality and shouldn't be used anywhere else!
	/// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	///
	/// Gets the current DB tracking whitelist.
	fn get_whitelist(&self) -> Vec<TrackedStorageKey>;

	/// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	/// Benchmarking related functionality and shouldn't be used anywhere else!
	/// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	///
	/// Adds new storage keys to the DB tracking whitelist.
	fn set_whitelist(&mut self, new: Vec<TrackedStorageKey>);

	/// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	/// Benchmarking related functionality and shouldn't be used anywhere else!
	/// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	///
	/// Returns estimated proof size for the state queries so far.
	/// Proof is reset on commit and wipe.
	fn proof_size(&self) -> Option<u32> {
		None
	}

	/// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	/// Benchmarking related functionality and shouldn't be used anywhere else!
	/// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	///
	/// Get all the keys that have been read or written to during the benchmark.
	fn get_read_and_written_keys(&self) -> Vec<(Vec<u8>, u32, u32, bool)>;
}

/// Extension for the [`Externalities`] trait.
pub trait ExternalitiesExt {
	/// Tries to find a registered extension and returns a mutable reference.
	fn extension<T: Any + Extension>(&mut self) -> Option<&mut T>;

	/// Register extension `ext`.
	///
	/// Should return error if extension is already registered or extensions are not supported.
	fn register_extension<T: Extension>(&mut self, ext: T) -> Result<(), Error>;

	/// Deregister and drop extension of `T` type.
	///
	/// Should return error if extension of type `T` is not registered or
	/// extensions are not supported.
	fn deregister_extension<T: Extension>(&mut self) -> Result<(), Error>;
}

impl ExternalitiesExt for &mut dyn Externalities {
	fn extension<T: Any + Extension>(&mut self) -> Option<&mut T> {
		self.extension_by_type_id(TypeId::of::<T>()).and_then(<dyn Any>::downcast_mut)
	}

	fn register_extension<T: Extension>(&mut self, ext: T) -> Result<(), Error> {
		self.register_extension_with_type_id(TypeId::of::<T>(), Box::new(ext))
	}

	fn deregister_extension<T: Extension>(&mut self) -> Result<(), Error> {
		self.deregister_extension_by_type_id(TypeId::of::<T>())
	}
}