VolumeControl

1access(all) contract VolumeControl {
2
3  access(all) let AdminPath: StoragePath
4  // ========== events ==========
5  access(all) event EpochLengthUpdated(length: UInt64)
6
7  access(all) var epochLength: UInt64 // seconds, how soon the volume in last window will be clear
8  access(account) var epochVolumes: {String: UFix64} // the sum volume in last time window
9  access(account) var lastOpTimestamps: {String: UInt64}  // unix seconds, the last time window record the volume
10
11  // ========== admin resource ==========
12  access(all) resource Admin {
13    access(all) fun setEpochLength(newLength: UInt64) {
14      VolumeControl.epochLength = newLength
15      emit EpochLengthUpdated(
16        length: newLength
17      )
18    }
19
20    // createNewAdmin creates a new Admin resource
21    access(all) fun createNewAdmin(): @Admin {
22      return <-create Admin()
23    }
24  }
25
26  // ========== functions ==========
27  init() {
28    self.epochLength = 0
29    self.epochVolumes = {}
30    self.lastOpTimestamps = {}
31    self.AdminPath = /storage/VolumeControlAdmin
32    self.account.storage.save<@Admin>(<- create Admin(), to: self.AdminPath)
33  }
34
35  access(account) fun updateVolume(token: String, amt: UFix64, cap: UFix64) {
36    if self.epochLength == 0 {
37      return
38    }
39    if cap == 0.0 {
40      return
41    }
42    var volume = self.epochVolumes[token] ?? 0.0
43    let timestamp = UInt64(getCurrentBlock().timestamp)
44    let epochStartTime = (timestamp / self.epochLength) * self.epochLength;
45    let lastOpTimestamp = self.lastOpTimestamps[token] ?? 0
46    if (lastOpTimestamp < epochStartTime) {
47       volume = amt
48    } else {
49       volume = volume + amt;
50    }
51    assert(volume <= cap, message: "volume exceeds cap")
52    self.epochVolumes[token] = volume;
53    self.lastOpTimestamps[token] = timestamp;
54  }
55
56  access(all) view fun getEpochVolume(token: String): UFix64 {
57    return self.epochVolumes[token] ?? 0.0
58  }
59
60  access(all) view fun getLastOpTimestamp(token: String): UInt64 {
61    return self.lastOpTimestamps[token] ?? 0
62  }
63}