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
use crate::clock::{DEFAULT_TICKS_PER_SECOND, DEFAULT_TICKS_PER_SLOT};
use crate::message::Message;
use crate::secp256k1_program;
use log::*;

#[derive(Serialize, Deserialize, PartialEq, Eq, Clone, Debug, AbiExample)]
#[serde(rename_all = "camelCase")]
pub struct FeeCalculator {
    // The current cost of a signature  This amount may increase/decrease over time based on
    // cluster processing load.
    pub lamports_per_signature: u64,
}

impl Default for FeeCalculator {
    fn default() -> Self {
        Self {
            lamports_per_signature: 0,
        }
    }
}

pub struct FeeConfig {
    pub secp256k1_program_enabled: bool,
}

impl Default for FeeConfig {
    fn default() -> Self {
        Self {
            secp256k1_program_enabled: true,
        }
    }
}

impl FeeCalculator {
    pub fn new(lamports_per_signature: u64) -> Self {
        Self {
            lamports_per_signature,
        }
    }

    pub fn calculate_fee(&self, message: &Message) -> u64 {
        self.calculate_fee_with_config(message, &FeeConfig::default())
    }

    pub fn calculate_fee_with_config(&self, message: &Message, fee_config: &FeeConfig) -> u64 {
        let mut num_secp256k1_signatures: u64 = 0;
        if fee_config.secp256k1_program_enabled {
            for instruction in &message.instructions {
                let program_index = instruction.program_id_index as usize;
                // Transaction may not be sanitized here
                if program_index < message.account_keys.len() {
                    let id = message.account_keys[program_index];
                    if secp256k1_program::check_id(&id) && !instruction.data.is_empty() {
                        num_secp256k1_signatures += instruction.data[0] as u64;
                    }
                }
            }
        }

        self.lamports_per_signature
            * (u64::from(message.header.num_required_signatures) + num_secp256k1_signatures)
    }
}

#[derive(Serialize, Deserialize, PartialEq, Eq, Clone, Debug, AbiExample)]
#[serde(rename_all = "camelCase")]
pub struct FeeRateGovernor {
    // The current cost of a signature  This amount may increase/decrease over time based on
    // cluster processing load.
    #[serde(skip)]
    pub lamports_per_signature: u64,

    // The target cost of a signature when the cluster is operating around target_signatures_per_slot
    // signatures
    pub target_lamports_per_signature: u64,

    // Used to estimate the desired processing capacity of the cluster.  As the signatures for
    // recent slots are fewer/greater than this value, lamports_per_signature will decrease/increase
    // for the next slot.  A value of 0 disables lamports_per_signature fee adjustments
    pub target_signatures_per_slot: u64,

    pub min_lamports_per_signature: u64,
    pub max_lamports_per_signature: u64,

    // What portion of collected fees are to be destroyed, as a fraction of std::u8::MAX
    pub burn_percent: u8,
}

pub const DEFAULT_TARGET_LAMPORTS_PER_SIGNATURE: u64 = 10_000;
pub const DEFAULT_TARGET_SIGNATURES_PER_SLOT: u64 =
    50_000 * DEFAULT_TICKS_PER_SLOT / DEFAULT_TICKS_PER_SECOND;

// Percentage of tx fees to burn
pub const DEFAULT_BURN_PERCENT: u8 = 50;

impl Default for FeeRateGovernor {
    fn default() -> Self {
        Self {
            lamports_per_signature: 0,
            target_lamports_per_signature: DEFAULT_TARGET_LAMPORTS_PER_SIGNATURE,
            target_signatures_per_slot: DEFAULT_TARGET_SIGNATURES_PER_SLOT,
            min_lamports_per_signature: 0,
            max_lamports_per_signature: 0,
            burn_percent: DEFAULT_BURN_PERCENT,
        }
    }
}

impl FeeRateGovernor {
    pub fn new(target_lamports_per_signature: u64, target_signatures_per_slot: u64) -> Self {
        let base_fee_rate_governor = Self {
            target_lamports_per_signature,
            lamports_per_signature: target_lamports_per_signature,
            target_signatures_per_slot,
            ..FeeRateGovernor::default()
        };

        Self::new_derived(&base_fee_rate_governor, 0)
    }

    pub fn new_derived(
        base_fee_rate_governor: &FeeRateGovernor,
        latest_signatures_per_slot: u64,
    ) -> Self {
        let mut me = base_fee_rate_governor.clone();

        if me.target_signatures_per_slot > 0 {
            // lamports_per_signature can range from 50% to 1000% of
            // target_lamports_per_signature
            me.min_lamports_per_signature = std::cmp::max(1, me.target_lamports_per_signature / 2);
            me.max_lamports_per_signature = me.target_lamports_per_signature * 10;

            // What the cluster should charge at `latest_signatures_per_slot`
            let desired_lamports_per_signature =
                me.max_lamports_per_signature
                    .min(me.min_lamports_per_signature.max(
                        me.target_lamports_per_signature
                            * std::cmp::min(latest_signatures_per_slot, std::u32::MAX as u64)
                                as u64
                            / me.target_signatures_per_slot as u64,
                    ));

            trace!(
                "desired_lamports_per_signature: {}",
                desired_lamports_per_signature
            );

            let gap = desired_lamports_per_signature as i64
                - base_fee_rate_governor.lamports_per_signature as i64;

            if gap == 0 {
                me.lamports_per_signature = desired_lamports_per_signature;
            } else {
                // Adjust fee by 5% of target_lamports_per_signature to produce a smooth
                // increase/decrease in fees over time.
                let gap_adjust =
                    std::cmp::max(1, me.target_lamports_per_signature / 20) as i64 * gap.signum();

                trace!(
                    "lamports_per_signature gap is {}, adjusting by {}",
                    gap,
                    gap_adjust
                );

                me.lamports_per_signature =
                    me.max_lamports_per_signature
                        .min(me.min_lamports_per_signature.max(
                            (base_fee_rate_governor.lamports_per_signature as i64 + gap_adjust)
                                as u64,
                        ));
            }
        } else {
            me.lamports_per_signature = base_fee_rate_governor.target_lamports_per_signature;
            me.min_lamports_per_signature = me.target_lamports_per_signature;
            me.max_lamports_per_signature = me.target_lamports_per_signature;
        }
        debug!(
            "new_derived(): lamports_per_signature: {}",
            me.lamports_per_signature
        );
        me
    }

    /// calculate unburned fee from a fee total, returns (unburned, burned)
    pub fn burn(&self, fees: u64) -> (u64, u64) {
        let burned = fees * u64::from(self.burn_percent) / 100;
        (fees - burned, burned)
    }

    /// create a FeeCalculator based on current cluster signature throughput
    pub fn create_fee_calculator(&self) -> FeeCalculator {
        FeeCalculator::new(self.lamports_per_signature)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::{pubkey::Pubkey, system_instruction};

    #[test]
    fn test_fee_rate_governor_burn() {
        let mut fee_rate_governor = FeeRateGovernor::default();
        assert_eq!(fee_rate_governor.burn(2), (1, 1));

        fee_rate_governor.burn_percent = 0;
        assert_eq!(fee_rate_governor.burn(2), (2, 0));

        fee_rate_governor.burn_percent = 100;
        assert_eq!(fee_rate_governor.burn(2), (0, 2));
    }

    #[test]
    fn test_fee_calculator_calculate_fee() {
        // Default: no fee.
        let message = Message::default();
        assert_eq!(FeeCalculator::default().calculate_fee(&message), 0);

        // No signature, no fee.
        assert_eq!(FeeCalculator::new(1).calculate_fee(&message), 0);

        // One signature, a fee.
        let pubkey0 = Pubkey::new(&[0; 32]);
        let pubkey1 = Pubkey::new(&[1; 32]);
        let ix0 = system_instruction::transfer(&pubkey0, &pubkey1, 1);
        let message = Message::new(&[ix0], Some(&pubkey0));
        assert_eq!(FeeCalculator::new(2).calculate_fee(&message), 2);

        // Two signatures, double the fee.
        let ix0 = system_instruction::transfer(&pubkey0, &pubkey1, 1);
        let ix1 = system_instruction::transfer(&pubkey1, &pubkey0, 1);
        let message = Message::new(&[ix0, ix1], Some(&pubkey0));
        assert_eq!(FeeCalculator::new(2).calculate_fee(&message), 4);
    }

    #[test]
    fn test_fee_calculator_calculate_fee_secp256k1() {
        use crate::instruction::Instruction;
        let pubkey0 = Pubkey::new(&[0; 32]);
        let pubkey1 = Pubkey::new(&[1; 32]);
        let ix0 = system_instruction::transfer(&pubkey0, &pubkey1, 1);
        let mut secp_instruction = Instruction {
            program_id: crate::secp256k1_program::id(),
            accounts: vec![],
            data: vec![],
        };
        let mut secp_instruction2 = Instruction {
            program_id: crate::secp256k1_program::id(),
            accounts: vec![],
            data: vec![1],
        };

        let message = Message::new(
            &[
                ix0.clone(),
                secp_instruction.clone(),
                secp_instruction2.clone(),
            ],
            Some(&pubkey0),
        );
        assert_eq!(FeeCalculator::new(1).calculate_fee(&message), 2);
        assert_eq!(
            FeeCalculator::new(1).calculate_fee_with_config(
                &message,
                &FeeConfig {
                    secp256k1_program_enabled: false
                }
            ),
            1
        );

        secp_instruction.data = vec![0];
        secp_instruction2.data = vec![10];
        let message = Message::new(&[ix0, secp_instruction, secp_instruction2], Some(&pubkey0));
        assert_eq!(FeeCalculator::new(1).calculate_fee(&message), 11);
    }

    #[test]
    fn test_fee_rate_governor_derived_default() {
        solana_logger::setup();

        let f0 = FeeRateGovernor::default();
        assert_eq!(
            f0.target_signatures_per_slot,
            DEFAULT_TARGET_SIGNATURES_PER_SLOT
        );
        assert_eq!(
            f0.target_lamports_per_signature,
            DEFAULT_TARGET_LAMPORTS_PER_SIGNATURE
        );
        assert_eq!(f0.lamports_per_signature, 0);

        let f1 = FeeRateGovernor::new_derived(&f0, DEFAULT_TARGET_SIGNATURES_PER_SLOT);
        assert_eq!(
            f1.target_signatures_per_slot,
            DEFAULT_TARGET_SIGNATURES_PER_SLOT
        );
        assert_eq!(
            f1.target_lamports_per_signature,
            DEFAULT_TARGET_LAMPORTS_PER_SIGNATURE
        );
        assert_eq!(
            f1.lamports_per_signature,
            DEFAULT_TARGET_LAMPORTS_PER_SIGNATURE / 2
        ); // min
    }

    #[test]
    fn test_fee_rate_governor_derived_adjust() {
        solana_logger::setup();

        let mut f = FeeRateGovernor {
            target_lamports_per_signature: 100,
            target_signatures_per_slot: 100,
            ..FeeRateGovernor::default()
        };
        f = FeeRateGovernor::new_derived(&f, 0);

        // Ramp fees up
        let mut count = 0;
        loop {
            let last_lamports_per_signature = f.lamports_per_signature;

            f = FeeRateGovernor::new_derived(&f, std::u64::MAX);
            info!("[up] f.lamports_per_signature={}", f.lamports_per_signature);

            // some maximum target reached
            if f.lamports_per_signature == last_lamports_per_signature {
                break;
            }
            // shouldn't take more than 1000 steps to get to minimum
            assert!(count < 1000);
            count += 1;
        }

        // Ramp fees down
        let mut count = 0;
        loop {
            let last_lamports_per_signature = f.lamports_per_signature;
            f = FeeRateGovernor::new_derived(&f, 0);

            info!(
                "[down] f.lamports_per_signature={}",
                f.lamports_per_signature
            );

            // some minimum target reached
            if f.lamports_per_signature == last_lamports_per_signature {
                break;
            }

            // shouldn't take more than 1000 steps to get to minimum
            assert!(count < 1000);
            count += 1;
        }

        // Arrive at target rate
        let mut count = 0;
        while f.lamports_per_signature != f.target_lamports_per_signature {
            f = FeeRateGovernor::new_derived(&f, f.target_signatures_per_slot);
            info!(
                "[target] f.lamports_per_signature={}",
                f.lamports_per_signature
            );
            // shouldn't take more than 100 steps to get to target
            assert!(count < 100);
            count += 1;
        }
    }
}