Scope

Scope sees all prices in one glance.

Scope is a price oracle aggregator living on the Solana network. It copies data from multiple on-chain oracles' accounts into one "price feed".

Scope prevalidate the prices with a preset of rules and perform the update only if they meet the criteria.

The repository contains two software:

• scope on-chain program.
• scope-cli that provide administration commands and a bot feature to trigger the price feed update.

Limitations

• The association between an price at a given index in the price feed and the token pair associated to this price need is not stored on chain.
• A price feed is currently limited to 512 prices.
• At the moment, only pyth prices are supported.

Future updates/ideas

• Support of switchboard as a price source.
• Support different refresh rates in the bot (stacked stable coin price change less often than other token).
• Open creation of price feed to any user who will became admin of the feed.
• Allow extensible price feed (when resizable account feature is available in Solana mainnet)

Example of crank refresh operation:

• For simplification let's say we only refresh at most 3 prices per IX.
• In this example, we have 10 prices in scope named A, B, C, D, E, F, G, H, I, J.
• We refresh any price older than 30 slots.
• If we fire an IX, we fill the IX as much as possible (minimum refresh size is 3).
• Price age is given by source oracle (pyth) not the current slot of refresh.

Steps

Loop 0

• Starting ages: A: 0, B: 5, C: 10, D: 15, E: 20, F: 25, G: 30, H: 35, I: 5, J: 10
• Refresh old prices:
  1. Sort price by ages (oldest first) H, G, F, E, D, C, J, B, I, A
  2. Divide by chunk of 3
  3. For each chunk if oldest price is more than 30, refresh chunk
  4. Only one refreshed chunk H, G, F
• After refresh operation new price ages is: A: 5, B: 10, C: 15, D: 20, E: 25, F: 12, G: 3, H: 3, I: 10, J: 15 (All prices are older by 5 slots about the time to execute the ix, and just refreshed prices are not at 0 because age come from the oracle)
• Get the new oldest price: E: 25, so sleep for 5 slot (400ms*5).
• Loop

Loop 1

• Starting ages: A: 10, B: 15, C: 20, D: 25, E: 30, F: 17, G: 8, H: 8, I: 15, J: 20
• Refresh old prices:
  1. Sort price by ages (oldest first) E, D, C, J, B, I, F, A, G, H
  2. Divide by chunk of 3
  3. For each chunk if oldest price is more than 30, refresh chunk
  4. Only one refreshed chunk E, D, C
• After refresh operation new price ages is: A: 15, B: 20, C: 3, D: 5, E: 3, F: 22, G: 13, H: 13, I: 20, J: 25
• Get the new oldest price: J: 25, so sleep for 5 slot (400ms*5).
• Loop