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
// This file is part of Substrate.

// Copyright (C) 2018-2021 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.

//! Substrate changes trie configuration.

#[cfg(any(feature = "std", test))]
use serde::{Serialize, Deserialize};
use codec::{Encode, Decode};
use num_traits::Zero;

/// Substrate changes trie configuration.
#[cfg_attr(any(feature = "std", test), derive(Serialize, Deserialize, parity_util_mem::MallocSizeOf))]
#[derive(Debug, Clone, PartialEq, Eq, Default, Encode, Decode)]
pub struct ChangesTrieConfiguration {
	/// Interval (in blocks) at which level1-digests are created. Digests are not
	/// created when this is less or equal to 1.
	pub digest_interval: u32,
	/// Maximal number of digest levels in hierarchy. 0 means that digests are not
	/// created at all (even level1 digests). 1 means only level1-digests are created.
	/// 2 means that every digest_interval^2 there will be a level2-digest, and so on.
	/// Please ensure that maximum digest interval (i.e. digest_interval^digest_levels)
	/// is within `u32` limits. Otherwise you'll never see digests covering such intervals
	/// && maximal digests interval will be truncated to the last interval that fits
	/// `u32` limits.
	pub digest_levels: u32,
}

/// Substrate changes trie configuration range.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ChangesTrieConfigurationRange<Number, Hash> {
	/// Zero block of configuration.
	pub zero: (Number, Hash),
	/// Last block of configuration (if configuration has been deactivated at some point).
	pub end: Option<(Number, Hash)>,
	/// The configuration itself. None if changes tries were disabled in this range.
	pub config: Option<ChangesTrieConfiguration>,
}

impl ChangesTrieConfiguration {
	/// Create new configuration given digest interval and levels.
	pub fn new(digest_interval: u32, digest_levels: u32) -> Self {
		Self { digest_interval, digest_levels }
	}

	/// Is digest build enabled?
	pub fn is_digest_build_enabled(&self) -> bool {
		self.digest_interval > 1 && self.digest_levels > 0
	}

	/// Do we need to build digest at given block?
	pub fn is_digest_build_required_at_block<Number>(
		&self,
		zero: Number,
		block: Number,
	) -> bool
		where
			Number: From<u32> + PartialEq +
			::sp_std::ops::Rem<Output=Number> + ::sp_std::ops::Sub<Output=Number> +
			::sp_std::cmp::PartialOrd + Zero,
	{
		block > zero
			&& self.is_digest_build_enabled()
			&& ((block - zero) % self.digest_interval.into()).is_zero()
	}

	/// Returns max digest interval. One if digests are not created at all.
	pub fn max_digest_interval(&self) -> u32 {
		if !self.is_digest_build_enabled() {
			return 1;
		}

		// we'll get >1 loop iteration only when bad configuration parameters are selected
		let mut current_level = self.digest_levels;
		loop {
			if let Some(max_digest_interval) = self.digest_interval.checked_pow(current_level) {
				return max_digest_interval;
			}

			current_level = current_level - 1;
		}
	}

	/// Returns max level digest block number that has been created at block <= passed block number.
	///
	/// Returns None if digests are not created at all.
	pub fn prev_max_level_digest_block<Number>(
		&self,
		zero: Number,
		block: Number,
	) -> Option<Number>
		where
			Number: Clone + From<u32> + PartialOrd + PartialEq +
			::sp_std::ops::Add<Output=Number> + ::sp_std::ops::Sub<Output=Number> +
			::sp_std::ops::Div<Output=Number> + ::sp_std::ops::Mul<Output=Number> + Zero,
	{
		if block <= zero {
			return None;
		}

		let (next_begin, next_end) = self.next_max_level_digest_range(zero.clone(), block.clone())?;

		// if 'next' digest includes our block, then it is a also a previous digest
		if next_end == block {
			return Some(block);
		}

		// if previous digest ends at zero block, then there are no previous digest
		let prev_end = next_begin - 1.into();
		if prev_end == zero {
			None
		} else {
			Some(prev_end)
		}
	}

	/// Returns max level digest blocks range (inclusive) which includes passed block.
	///
	/// Returns None if digests are not created at all.
	/// It will return the first max-level digest if block is <= zero.
	pub fn next_max_level_digest_range<Number>(
		&self,
		zero: Number,
		mut block: Number,
	) -> Option<(Number, Number)>
		where
			Number: Clone + From<u32> + PartialOrd + PartialEq +
			::sp_std::ops::Add<Output=Number> + ::sp_std::ops::Sub<Output=Number> +
			::sp_std::ops::Div<Output=Number> + ::sp_std::ops::Mul<Output=Number>,
	{
		if !self.is_digest_build_enabled() {
			return None;
		}

		if block <= zero {
			block = zero.clone() + 1.into();
		}

		let max_digest_interval: Number = self.max_digest_interval().into();
		let max_digests_since_zero = (block.clone() - zero.clone()) / max_digest_interval.clone();
		if max_digests_since_zero == 0.into() {
			return Some((zero.clone() + 1.into(), zero + max_digest_interval));
		}
		let last_max_digest_block = zero + max_digests_since_zero * max_digest_interval.clone();
		Some(if block == last_max_digest_block {
			(block.clone() - max_digest_interval + 1.into(), block)
		} else {
			(last_max_digest_block.clone() + 1.into(), last_max_digest_block + max_digest_interval)
		})
	}

	/// Returns Some if digest must be built at given block number.
	/// The tuple is:
	/// (
	///  digest level
	///  digest interval (in blocks)
	///  step between blocks we're interested in when digest is built
	/// )
	pub fn digest_level_at_block<Number>(&self, zero: Number, block: Number) -> Option<(u32, u32, u32)>
		where
			Number: Clone + From<u32> + PartialEq +
			::sp_std::ops::Rem<Output=Number> + ::sp_std::ops::Sub<Output=Number> +
			::sp_std::cmp::PartialOrd + Zero,
	{
		if !self.is_digest_build_required_at_block(zero.clone(), block.clone()) {
			return None;
		}

		let relative_block = block - zero;
		let mut digest_interval = self.digest_interval;
		let mut current_level = 1u32;
		let mut digest_step = 1u32;
		while current_level < self.digest_levels {
			let new_digest_interval = match digest_interval.checked_mul(self.digest_interval) {
				Some(new_digest_interval) if (relative_block.clone() % new_digest_interval.into()).is_zero()
					=> new_digest_interval,
				_ => break,
			};

			digest_step = digest_interval;
			digest_interval = new_digest_interval;
			current_level = current_level + 1;
		}

		Some((
			current_level,
			digest_interval,
			digest_step,
		))
	}
}

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

	fn config(interval: u32, levels: u32) -> ChangesTrieConfiguration {
		ChangesTrieConfiguration {
			digest_interval: interval,
			digest_levels: levels,
		}
	}

	#[test]
	fn is_digest_build_enabled_works() {
		assert!(!config(0, 100).is_digest_build_enabled());
		assert!(!config(1, 100).is_digest_build_enabled());
		assert!(config(2, 100).is_digest_build_enabled());
		assert!(!config(100, 0).is_digest_build_enabled());
		assert!(config(100, 1).is_digest_build_enabled());
	}

	#[test]
	fn is_digest_build_required_at_block_works() {
		fn test_with_zero(zero: u64) {
			assert!(!config(8, 4).is_digest_build_required_at_block(zero, zero + 0u64));
			assert!(!config(8, 4).is_digest_build_required_at_block(zero, zero + 1u64));
			assert!(!config(8, 4).is_digest_build_required_at_block(zero, zero + 2u64));
			assert!(!config(8, 4).is_digest_build_required_at_block(zero, zero + 4u64));
			assert!(config(8, 4).is_digest_build_required_at_block(zero, zero + 8u64));
			assert!(!config(8, 4).is_digest_build_required_at_block(zero, zero + 9u64));
			assert!(config(8, 4).is_digest_build_required_at_block(zero, zero + 64u64));
			assert!(config(8, 4).is_digest_build_required_at_block(zero, zero + 64u64));
			assert!(config(8, 4).is_digest_build_required_at_block(zero, zero + 512u64));
			assert!(config(8, 4).is_digest_build_required_at_block(zero, zero + 4096u64));
			assert!(!config(8, 4).is_digest_build_required_at_block(zero, zero + 4103u64));
			assert!(config(8, 4).is_digest_build_required_at_block(zero, zero + 4104u64));
			assert!(!config(8, 4).is_digest_build_required_at_block(zero, zero + 4108u64));
		}

		test_with_zero(0);
		test_with_zero(8);
		test_with_zero(17);
	}

	#[test]
	fn digest_level_at_block_works() {
		fn test_with_zero(zero: u64) {
			assert_eq!(config(8, 4).digest_level_at_block(zero, zero + 0u64), None);
			assert_eq!(config(8, 4).digest_level_at_block(zero, zero + 7u64), None);
			assert_eq!(config(8, 4).digest_level_at_block(zero, zero + 63u64), None);
			assert_eq!(config(8, 4).digest_level_at_block(zero, zero + 8u64), Some((1, 8, 1)));
			assert_eq!(config(8, 4).digest_level_at_block(zero, zero + 64u64), Some((2, 64, 8)));
			assert_eq!(config(8, 4).digest_level_at_block(zero, zero + 512u64), Some((3, 512, 64)));
			assert_eq!(config(8, 4).digest_level_at_block(zero, zero + 4096u64), Some((4, 4096, 512)));
			assert_eq!(config(8, 4).digest_level_at_block(zero, zero + 4112u64), Some((1, 8, 1)));
		}

		test_with_zero(0);
		test_with_zero(8);
		test_with_zero(17);
	}

	#[test]
	fn max_digest_interval_works() {
		assert_eq!(config(0, 0).max_digest_interval(), 1);
		assert_eq!(config(2, 2).max_digest_interval(), 4);
		assert_eq!(config(8, 4).max_digest_interval(), 4096);
		assert_eq!(config(::std::u32::MAX, 1024).max_digest_interval(), ::std::u32::MAX);
	}

	#[test]
	fn next_max_level_digest_range_works() {
		assert_eq!(config(0, 0).next_max_level_digest_range(0u64, 16), None);
		assert_eq!(config(1, 1).next_max_level_digest_range(0u64, 16), None);
		assert_eq!(config(2, 1).next_max_level_digest_range(0u64, 16), Some((15, 16)));
		assert_eq!(config(4, 1).next_max_level_digest_range(0u64, 16), Some((13, 16)));
		assert_eq!(config(32, 1).next_max_level_digest_range(0u64, 16), Some((1, 32)));
		assert_eq!(config(2, 3).next_max_level_digest_range(0u64, 10), Some((9, 16)));
		assert_eq!(config(2, 3).next_max_level_digest_range(0u64, 8), Some((1, 8)));
		assert_eq!(config(2, 1).next_max_level_digest_range(1u64, 1), Some((2, 3)));
		assert_eq!(config(2, 2).next_max_level_digest_range(7u64, 9), Some((8, 11)));

		assert_eq!(config(2, 2).next_max_level_digest_range(7u64, 5), Some((8, 11)));
	}

	#[test]
	fn prev_max_level_digest_block_works() {
		assert_eq!(config(0, 0).prev_max_level_digest_block(0u64, 16), None);
		assert_eq!(config(1, 1).prev_max_level_digest_block(0u64, 16), None);
		assert_eq!(config(2, 1).prev_max_level_digest_block(0u64, 16), Some(16));
		assert_eq!(config(4, 1).prev_max_level_digest_block(0u64, 16), Some(16));
		assert_eq!(config(4, 2).prev_max_level_digest_block(0u64, 16), Some(16));
		assert_eq!(config(4, 2).prev_max_level_digest_block(0u64, 17), Some(16));
		assert_eq!(config(4, 2).prev_max_level_digest_block(0u64, 33), Some(32));
		assert_eq!(config(32, 1).prev_max_level_digest_block(0u64, 16), None);
		assert_eq!(config(2, 3).prev_max_level_digest_block(0u64, 10), Some(8));
		assert_eq!(config(2, 3).prev_max_level_digest_block(0u64, 8), Some(8));
		assert_eq!(config(2, 2).prev_max_level_digest_block(7u64, 8), None);

		assert_eq!(config(2, 2).prev_max_level_digest_block(7u64, 5), None);
	}
}