perp funding (#51)

Signed-off-by: microwavedcola1 <microwavedcola@gmail.com>

programs/mango-v4/src/instructions/mod.rs

@@ -21,6 +21,7 @@ pub use serum3_place_order::*;
 pub use serum3_register_market::*;
 pub use serum3_settle_funds::*;
 pub use set_stub_oracle::*;
+pub use update_funding::*;
 pub use update_index::*;
 pub use withdraw::*;
 
@@ -47,5 +48,6 @@ mod serum3_place_order;
 mod serum3_register_market;
 mod serum3_settle_funds;
 mod set_stub_oracle;
+mod update_funding;
 mod update_index;
 mod withdraw;

programs/mango-v4/src/instructions/perp_create_market.rs

@@ -1,5 +1,6 @@
 use anchor_lang::prelude::*;
 use fixed::types::I80F48;
+use fixed_macro::types::I80F48;
 
 use crate::error::MangoError;
 use crate::state::*;
@@ -56,6 +57,9 @@ pub fn perp_create_market(
     liquidation_fee: f32,
     maker_fee: f32,
     taker_fee: f32,
+    max_funding: f32,
+    min_funding: f32,
+    impact_quantity: u64,
 ) -> Result<()> {
     let mut perp_market = ctx.accounts.perp_market.load_init()?;
     *perp_market = PerpMarket {
@@ -74,14 +78,20 @@ pub fn perp_create_market(
         liquidation_fee: I80F48::from_num(liquidation_fee),
         maker_fee: I80F48::from_num(maker_fee),
         taker_fee: I80F48::from_num(taker_fee),
+        max_funding: I80F48!(0.05),
+        min_funding: I80F48!(0.05),
+        long_funding: I80F48::ZERO,
+        short_funding: I80F48::ZERO,
+        funding_last_updated: Clock::get()?.unix_timestamp,
+        impact_quantity: 100,
         open_interest: 0,
         seq_num: 0,
         fees_accrued: I80F48::ZERO,
         bump: *ctx.bumps.get("perp_market").ok_or(MangoError::SomeError)?,
+        reserved: Default::default(),
         perp_market_index,
         base_token_index: base_token_index_opt.ok_or(TokenIndex::MAX).unwrap(),
         quote_token_index,
-        reserved: Default::default(),
     };
 
     let mut bids = ctx.accounts.bids.load_init()?;

programs/mango-v4/src/instructions/update_funding.rs

@@ -0,0 +1,35 @@
+use anchor_lang::prelude::*;
+
+use crate::state::{oracle_price, Book, PerpMarket};
+
+#[derive(Accounts)]
+pub struct UpdateFunding<'info> {
+    #[account(
+        mut,
+        has_one = bids,
+        has_one = asks,
+        has_one = oracle,
+    )]
+    pub perp_market: AccountLoader<'info, PerpMarket>,
+    #[account(mut)]
+    pub asks: UncheckedAccount<'info>,
+    #[account(mut)]
+    pub bids: UncheckedAccount<'info>,
+
+    pub oracle: UncheckedAccount<'info>,
+}
+pub fn update_funding(ctx: Context<UpdateFunding>) -> Result<()> {
+    // TODO: should we enforce a minimum window between 2 update_funding ix calls?
+    let now_ts = Clock::get()?.unix_timestamp;
+
+    let mut perp_market = ctx.accounts.perp_market.load_mut()?;
+    let bids = &ctx.accounts.bids.to_account_info();
+    let asks = &ctx.accounts.asks.to_account_info();
+    let book = Book::load_mut(bids, asks, &perp_market)?;
+
+    let oracle_price = oracle_price(&ctx.accounts.oracle.to_account_info())?;
+
+    perp_market.update_funding(&book, oracle_price, now_ts as u64)?;
+
+    Ok(())
+}

programs/mango-v4/src/state/bank.rs

@@ -7,6 +7,7 @@ use fixed_macro::types::I80F48;
 use static_assertions::const_assert_eq;
 use std::mem::size_of;
 
+pub const DAY: I80F48 = I80F48!(86400);
 pub const YEAR: I80F48 = I80F48!(31536000);
 
 #[account(zero_copy)]

programs/mango-v4/src/state/mango_account.rs

@@ -288,8 +288,8 @@ pub struct PerpAccount {
     pub quote_position_native: I80F48,
 
     /// Already settled funding
-    // pub long_settled_funding: I80F48,
-    // pub short_settled_funding: I80F48,
+    pub long_settled_funding: I80F48,
+    pub short_settled_funding: I80F48,
 
     /// Base lots in bids
     pub bids_base_lots: i64,
@@ -317,7 +317,7 @@ impl std::fmt::Debug for PerpAccount {
             .finish()
     }
 }
-const_assert_eq!(size_of::<PerpAccount>(), 8 + 8 * 5 + 16);
+const_assert_eq!(size_of::<PerpAccount>(), 8 + 8 * 5 + 3 * 16);
 const_assert_eq!(size_of::<PerpAccount>() % 8, 0);
 
 impl Default for PerpAccount {
@@ -331,6 +331,8 @@ impl Default for PerpAccount {
             taker_base_lots: 0,
             taker_quote_lots: 0,
             reserved: Default::default(),
+            long_settled_funding: I80F48::ZERO,
+            short_settled_funding: I80F48::ZERO,
         }
     }
 }
@@ -369,6 +371,19 @@ impl PerpAccount {
         self.base_position_lots += base_change;
         perp_market.open_interest += self.base_position_lots.abs() - start.abs();
     }
+
+    /// Move unrealized funding payments into the quote_position
+    pub fn settle_funding(&mut self, perp_market: &PerpMarket) {
+        if self.base_position_lots > 0 {
+            self.quote_position_native -= (perp_market.long_funding - self.long_settled_funding)
+                * I80F48::from_num(self.base_position_lots);
+        } else if self.base_position_lots < 0 {
+            self.quote_position_native -= (perp_market.short_funding - self.short_settled_funding)
+                * I80F48::from_num(self.base_position_lots);
+        }
+        self.long_settled_funding = perp_market.long_funding;
+        self.short_settled_funding = perp_market.short_funding;
+    }
 }
 
 #[zero_copy]
@@ -547,7 +562,7 @@ impl MangoAccountPerps {
         fill: &FillEvent,
     ) -> Result<()> {
         let pa = self.get_account_mut_or_create(perp_market_index).unwrap().0;
-        // pa.settle_funding(cache);
+        pa.settle_funding(perp_market);
 
         let side = fill.taker_side.invert_side();
         let (base_change, quote_change) = fill.base_quote_change(side);
@@ -586,6 +601,8 @@ impl MangoAccountPerps {
         fill: &FillEvent,
     ) -> Result<()> {
         let pa = self.get_account_mut_or_create(perp_market_index).unwrap().0;
+        pa.settle_funding(perp_market);
+
         let (base_change, quote_change) = fill.base_quote_change(fill.taker_side);
         pa.remove_taker_trade(base_change, quote_change);
         pa.change_base_position(perp_market, base_change);

programs/mango-v4/src/state/perp_market.rs

@@ -2,12 +2,15 @@ use std::mem::size_of;
 
 use anchor_lang::prelude::*;
 use fixed::types::I80F48;
+
 use static_assertions::const_assert_eq;
 
 use crate::state::orderbook::order_type::Side;
-use crate::state::TokenIndex;
+use crate::state::{TokenIndex, DAY};
 use crate::util::checked_math as cm;
 
+use super::Book;
+
 pub type PerpMarketIndex = u16;
 
 #[account(zero_copy)]
@@ -44,9 +47,12 @@ pub struct PerpMarket {
     pub maker_fee: I80F48,
     pub taker_fee: I80F48,
 
-    /// pub long_funding: I80F48,
-    /// pub short_funding: I80F48,
-    /// pub funding_last_updated: u64,
+    pub max_funding: I80F48,
+    pub min_funding: I80F48,
+    pub long_funding: I80F48,
+    pub short_funding: I80F48,
+    pub funding_last_updated: i64,
+    pub impact_quantity: i64,
 
     ///
     pub open_interest: i64,
@@ -77,7 +83,7 @@ pub struct PerpMarket {
 
 const_assert_eq!(
     size_of::<PerpMarket>(),
-    16 + 32 * 5 + 8 * 2 + 16 * 7 + 8 * 2 + 16 + 8
+    16 + 32 * 5 + 8 * 2 + 16 * 11 + 8 * 2 + 8 * 2 + 16 + 8
 );
 const_assert_eq!(size_of::<PerpMarket>() % 8, 0);
 
@@ -98,6 +104,38 @@ impl PerpMarket {
         }
     }
 
+    /// Use current order book price and index price to update the instantaneous funding
+    pub fn update_funding(&mut self, book: &Book, oracle_price: I80F48, now_ts: u64) -> Result<()> {
+        let index_price = oracle_price;
+
+        // Get current book price & compare it to index price
+        let bid = book.get_impact_price(Side::Bid, self.impact_quantity, now_ts);
+        let ask = book.get_impact_price(Side::Ask, self.impact_quantity, now_ts);
+
+        let diff_price = match (bid, ask) {
+            (Some(bid), Some(ask)) => {
+                // calculate mid-market rate
+                let book_price = self.lot_to_native_price((bid + ask) / 2);
+                let diff = cm!(book_price / index_price - I80F48::ONE);
+                diff.clamp(self.min_funding, self.max_funding)
+            }
+            (Some(_bid), None) => self.max_funding,
+            (None, Some(_ask)) => self.min_funding,
+            (None, None) => I80F48::ZERO,
+        };
+
+        let diff_ts = I80F48::from_num(now_ts - self.funding_last_updated as u64);
+        let time_factor = cm!(diff_ts / DAY);
+        let base_lot_size = I80F48::from_num(self.base_lot_size);
+        let funding_delta = cm!(index_price * diff_price * base_lot_size * time_factor);
+
+        self.long_funding += funding_delta;
+        self.short_funding += funding_delta;
+        self.funding_last_updated = now_ts as i64;
+
+        Ok(())
+    }
+
     /// Convert from the price stored on the book to the price used in value calculations
     pub fn lot_to_native_price(&self, price: i64) -> I80F48 {
         I80F48::from_num(price)