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
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
// This file is part of Substrate.

// Copyright (C) 2017-2021 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.

//! Primitive types for storage related stuff.

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

#[cfg(feature = "std")]
use serde::{Deserialize, Serialize};
use sp_debug_derive::RuntimeDebug;

use codec::{Decode, Encode};
use ref_cast::RefCast;
use sp_std::{
	ops::{Deref, DerefMut},
	vec::Vec,
};

/// Storage key.
#[derive(PartialEq, Eq, RuntimeDebug)]
#[cfg_attr(
	feature = "std",
	derive(Serialize, Deserialize, Hash, PartialOrd, Ord, Clone, Encode, Decode)
)]
pub struct StorageKey(
	#[cfg_attr(feature = "std", serde(with = "impl_serde::serialize"))] pub Vec<u8>,
);

impl AsRef<[u8]> for StorageKey {
	fn as_ref(&self) -> &[u8] {
		self.0.as_ref()
	}
}

/// Storage key with read/write tracking information.
#[derive(PartialEq, Eq, RuntimeDebug, Clone, Encode, Decode)]
#[cfg_attr(feature = "std", derive(Hash, PartialOrd, Ord))]
pub struct TrackedStorageKey {
	pub key: Vec<u8>,
	pub reads: u32,
	pub writes: u32,
	pub whitelisted: bool,
}

impl TrackedStorageKey {
	/// Create a default `TrackedStorageKey`
	pub fn new(key: Vec<u8>) -> Self {
		Self { key, reads: 0, writes: 0, whitelisted: false }
	}
	/// Check if this key has been "read", i.e. it exists in the memory overlay.
	///
	/// Can be true if the key has been read, has been written to, or has been
	/// whitelisted.
	pub fn has_been_read(&self) -> bool {
		self.whitelisted || self.reads > 0u32 || self.has_been_written()
	}
	/// Check if this key has been "written", i.e. a new value will be committed to the database.
	///
	/// Can be true if the key has been written to, or has been whitelisted.
	pub fn has_been_written(&self) -> bool {
		self.whitelisted || self.writes > 0u32
	}
	/// Add a storage read to this key.
	pub fn add_read(&mut self) {
		self.reads += 1;
	}
	/// Add a storage write to this key.
	pub fn add_write(&mut self) {
		self.writes += 1;
	}
	/// Whitelist this key.
	pub fn whitelist(&mut self) {
		self.whitelisted = true;
	}
}

// Easily convert a key to a `TrackedStorageKey` that has been whitelisted.
impl From<Vec<u8>> for TrackedStorageKey {
	fn from(key: Vec<u8>) -> Self {
		Self { key, reads: 0, writes: 0, whitelisted: true }
	}
}

/// Storage key of a child trie, it contains the prefix to the key.
#[derive(PartialEq, Eq, RuntimeDebug)]
#[cfg_attr(feature = "std", derive(Serialize, Deserialize, Hash, PartialOrd, Ord, Clone))]
#[repr(transparent)]
#[derive(RefCast)]
pub struct PrefixedStorageKey(
	#[cfg_attr(feature = "std", serde(with = "impl_serde::serialize"))] Vec<u8>,
);

impl Deref for PrefixedStorageKey {
	type Target = Vec<u8>;

	fn deref(&self) -> &Vec<u8> {
		&self.0
	}
}

impl DerefMut for PrefixedStorageKey {
	fn deref_mut(&mut self) -> &mut Vec<u8> {
		&mut self.0
	}
}

impl PrefixedStorageKey {
	/// Create a prefixed storage key from its byte array
	/// representation.
	pub fn new(inner: Vec<u8>) -> Self {
		PrefixedStorageKey(inner)
	}

	/// Create a prefixed storage key reference.
	pub fn new_ref(inner: &Vec<u8>) -> &Self {
		PrefixedStorageKey::ref_cast(inner)
	}

	/// Get inner key, this should
	/// only be needed when writing
	/// into parent trie to avoid an
	/// allocation.
	pub fn into_inner(self) -> Vec<u8> {
		self.0
	}
}

/// Storage data associated to a [`StorageKey`].
#[derive(PartialEq, Eq, RuntimeDebug)]
#[cfg_attr(
	feature = "std",
	derive(Serialize, Deserialize, Hash, PartialOrd, Ord, Clone, Encode, Decode, Default)
)]
pub struct StorageData(
	#[cfg_attr(feature = "std", serde(with = "impl_serde::serialize"))] pub Vec<u8>,
);

/// Map of data to use in a storage, it is a collection of
/// byte key and values.
#[cfg(feature = "std")]
pub type StorageMap = std::collections::BTreeMap<Vec<u8>, Vec<u8>>;

/// Child trie storage data.
#[cfg(feature = "std")]
#[derive(Debug, PartialEq, Eq, Clone)]
pub struct StorageChild {
	/// Child data for storage.
	pub data: StorageMap,
	/// Associated child info for a child
	/// trie.
	pub child_info: ChildInfo,
}

/// Struct containing data needed for a storage.
#[cfg(feature = "std")]
#[derive(Default, Debug, Clone)]
pub struct Storage {
	/// Top trie storage data.
	pub top: StorageMap,
	/// Children trie storage data.
	/// The key does not including prefix, for the `default`
	/// trie kind, so this is exclusively for the `ChildType::ParentKeyId`
	/// tries.
	pub children_default: std::collections::HashMap<Vec<u8>, StorageChild>,
}

/// Storage change set
#[derive(RuntimeDebug)]
#[cfg_attr(feature = "std", derive(Serialize, Deserialize, PartialEq, Eq))]
#[cfg_attr(feature = "std", serde(rename_all = "camelCase"))]
pub struct StorageChangeSet<Hash> {
	/// Block hash
	pub block: Hash,
	/// A list of changes
	pub changes: Vec<(StorageKey, Option<StorageData>)>,
}

/// List of all well known keys and prefixes in storage.
pub mod well_known_keys {
	/// Wasm code of the runtime.
	///
	/// Stored as a raw byte vector. Required by substrate.
	pub const CODE: &'static [u8] = b":code";

	/// Number of wasm linear memory pages required for execution of the runtime.
	///
	/// The type of this value is encoded `u64`.
	pub const HEAP_PAGES: &'static [u8] = b":heappages";

	/// Current extrinsic index (u32) is stored under this key.
	pub const EXTRINSIC_INDEX: &'static [u8] = b":extrinsic_index";

	/// Prefix of child storage keys.
	pub const CHILD_STORAGE_KEY_PREFIX: &'static [u8] = b":child_storage:";

	/// Prefix of the default child storage keys in the top trie.
	pub const DEFAULT_CHILD_STORAGE_KEY_PREFIX: &'static [u8] = b":child_storage:default:";

	/// Whether a key is a child storage key.
	///
	/// This is convenience function which basically checks if the given `key` starts
	/// with `CHILD_STORAGE_KEY_PREFIX` and doesn't do anything apart from that.
	pub fn is_child_storage_key(key: &[u8]) -> bool {
		// Other code might depend on this, so be careful changing this.
		key.starts_with(CHILD_STORAGE_KEY_PREFIX)
	}

	/// Returns if the given `key` starts with [`CHILD_STORAGE_KEY_PREFIX`] or collides with it.
	pub fn starts_with_child_storage_key(key: &[u8]) -> bool {
		if key.len() > CHILD_STORAGE_KEY_PREFIX.len() {
			key.starts_with(CHILD_STORAGE_KEY_PREFIX)
		} else {
			CHILD_STORAGE_KEY_PREFIX.starts_with(key)
		}
	}
}

/// Information related to a child state.
#[derive(Debug, Clone)]
#[cfg_attr(feature = "std", derive(PartialEq, Eq, Hash, PartialOrd, Ord))]
pub enum ChildInfo {
	/// This is the one used by default.
	ParentKeyId(ChildTrieParentKeyId),
}

impl ChildInfo {
	/// Instantiates child information for a default child trie
	/// of kind `ChildType::ParentKeyId`, using an unprefixed parent
	/// storage key.
	pub fn new_default(storage_key: &[u8]) -> Self {
		let data = storage_key.to_vec();
		ChildInfo::ParentKeyId(ChildTrieParentKeyId { data })
	}

	/// Same as `new_default` but with `Vec<u8>` as input.
	pub fn new_default_from_vec(storage_key: Vec<u8>) -> Self {
		ChildInfo::ParentKeyId(ChildTrieParentKeyId { data: storage_key })
	}

	/// Try to update with another instance, return false if both instance
	/// are not compatible.
	pub fn try_update(&mut self, other: &ChildInfo) -> bool {
		match self {
			ChildInfo::ParentKeyId(child_trie) => child_trie.try_update(other),
		}
	}

	/// Returns byte sequence (keyspace) that can be use by underlying db to isolate keys.
	/// This is a unique id of the child trie. The collision resistance of this value
	/// depends on the type of child info use. For `ChildInfo::Default` it is and need to be.
	pub fn keyspace(&self) -> &[u8] {
		match self {
			ChildInfo::ParentKeyId(..) => self.storage_key(),
		}
	}

	/// Returns a reference to the location in the direct parent of
	/// this trie but without the common prefix for this kind of
	/// child trie.
	pub fn storage_key(&self) -> &[u8] {
		match self {
			ChildInfo::ParentKeyId(ChildTrieParentKeyId { data }) => &data[..],
		}
	}

	/// Return a the full location in the direct parent of
	/// this trie.
	pub fn prefixed_storage_key(&self) -> PrefixedStorageKey {
		match self {
			ChildInfo::ParentKeyId(ChildTrieParentKeyId { data }) =>
				ChildType::ParentKeyId.new_prefixed_key(data.as_slice()),
		}
	}

	/// Returns a the full location in the direct parent of
	/// this trie.
	pub fn into_prefixed_storage_key(self) -> PrefixedStorageKey {
		match self {
			ChildInfo::ParentKeyId(ChildTrieParentKeyId { mut data }) => {
				ChildType::ParentKeyId.do_prefix_key(&mut data);
				PrefixedStorageKey(data)
			},
		}
	}

	/// Returns the type for this child info.
	pub fn child_type(&self) -> ChildType {
		match self {
			ChildInfo::ParentKeyId(..) => ChildType::ParentKeyId,
		}
	}
}

/// Type of child.
/// It does not strictly define different child type, it can also
/// be related to technical consideration or api variant.
#[repr(u32)]
#[derive(Clone, Copy, PartialEq)]
#[cfg_attr(feature = "std", derive(Debug))]
pub enum ChildType {
	/// If runtime module ensures that the child key is a unique id that will
	/// only be used once, its parent key is used as a child trie unique id.
	ParentKeyId = 1,
}

impl ChildType {
	/// Try to get a child type from its `u32` representation.
	pub fn new(repr: u32) -> Option<ChildType> {
		Some(match repr {
			r if r == ChildType::ParentKeyId as u32 => ChildType::ParentKeyId,
			_ => return None,
		})
	}

	/// Transform a prefixed key into a tuple of the child type
	/// and the unprefixed representation of the key.
	pub fn from_prefixed_key<'a>(storage_key: &'a PrefixedStorageKey) -> Option<(Self, &'a [u8])> {
		let match_type = |storage_key: &'a [u8], child_type: ChildType| {
			let prefix = child_type.parent_prefix();
			if storage_key.starts_with(prefix) {
				Some((child_type, &storage_key[prefix.len()..]))
			} else {
				None
			}
		};
		match_type(storage_key, ChildType::ParentKeyId)
	}

	/// Produce a prefixed key for a given child type.
	fn new_prefixed_key(&self, key: &[u8]) -> PrefixedStorageKey {
		let parent_prefix = self.parent_prefix();
		let mut result = Vec::with_capacity(parent_prefix.len() + key.len());
		result.extend_from_slice(parent_prefix);
		result.extend_from_slice(key);
		PrefixedStorageKey(result)
	}

	/// Prefixes a vec with the prefix for this child type.
	fn do_prefix_key(&self, key: &mut Vec<u8>) {
		let parent_prefix = self.parent_prefix();
		let key_len = key.len();
		if parent_prefix.len() > 0 {
			key.resize(key_len + parent_prefix.len(), 0);
			key.copy_within(..key_len, parent_prefix.len());
			key[..parent_prefix.len()].copy_from_slice(parent_prefix);
		}
	}

	/// Returns the location reserved for this child trie in their parent trie if there
	/// is one.
	pub fn parent_prefix(&self) -> &'static [u8] {
		match self {
			&ChildType::ParentKeyId => well_known_keys::DEFAULT_CHILD_STORAGE_KEY_PREFIX,
		}
	}
}

/// A child trie of default type.
/// It uses the same default implementation as the top trie,
/// top trie being a child trie with no keyspace and no storage key.
/// Its keyspace is the variable (unprefixed) part of its storage key.
/// It shares its trie nodes backend storage with every other
/// child trie, so its storage key needs to be a unique id
/// that will be use only once.
/// Those unique id also required to be long enough to avoid any
/// unique id to be prefixed by an other unique id.
#[derive(Debug, Clone)]
#[cfg_attr(feature = "std", derive(PartialEq, Eq, Hash, PartialOrd, Ord))]
pub struct ChildTrieParentKeyId {
	/// Data is the storage key without prefix.
	data: Vec<u8>,
}

impl ChildTrieParentKeyId {
	/// Try to update with another instance, return false if both instance
	/// are not compatible.
	fn try_update(&mut self, other: &ChildInfo) -> bool {
		match other {
			ChildInfo::ParentKeyId(other) => self.data[..] == other.data[..],
		}
	}
}

#[cfg(test)]
mod tests {
	use super::*;

	#[test]
	fn test_prefix_default_child_info() {
		let child_info = ChildInfo::new_default(b"any key");
		let prefix = child_info.child_type().parent_prefix();
		assert!(prefix.starts_with(well_known_keys::CHILD_STORAGE_KEY_PREFIX));
		assert!(prefix.starts_with(well_known_keys::DEFAULT_CHILD_STORAGE_KEY_PREFIX));
	}
}