Finalize pseudo-randomness, tidy up vars

src/move/emojicoin_arena/sources/emojicoin_arena.move

@@ -7,6 +7,7 @@ module arena::emojicoin_arena {
     use aptos_framework::randomness::Self;
     use aptos_framework::timestamp;
     use aptos_std::smart_table::{Self, SmartTable};
+    use arena::pseudo_randomness;
     use emojicoin_dot_fun::emojicoin_dot_fun::{
         Self,
         MarketMetadata,
@@ -39,9 +40,9 @@ module arena::emojicoin_arena {
     const MAX_MATCH_AMOUNT: u64 = 100_000_000;
 
     struct Melee has copy, drop, store {
-        /// 1-indexed for conformity with market ID indexing.
+        /// 1-indexed for conformity with emojicoin market ID indexing.
         melee_id: u64,
-        /// Market with lower market ID first.
+        /// Metadata for market with lower market ID comes first.
         market_metadatas: vector<MarketMetadata>,
         available_rewards_in_octas: u64,
         /// In microseconds.
@@ -63,7 +64,7 @@ module arena::emojicoin_arena {
         /// Map from melee serial ID to the melee.
         melees_by_id: SmartTable<u64, Melee>,
         /// Map from a sorted combination of market IDs (lower ID first) to the melee serial ID.
-        melees_by_market_combo_sorted_market_ids: SmartTable<vector<u64>, u64>,
+        melee_ids_by_market_ids: SmartTable<vector<u64>, u64>,
         /// Approves transfers from the vault.
         signer_capability: SignerCapability
     }
@@ -254,8 +255,8 @@ module arena::emojicoin_arena {
     ) acquires MeleeEscrow, Registry {
         let exit_once_done = crank_schedule();
 
-        // Return early if type arguments or melee ID is passed incorrectly, but only after cranking
-        // schedule.
+        // Return early if type arguments or melee ID are passed incorrectly, but only after
+        // cranking schedule.
         let swapper_address = signer::address_of(swapper);
         if (!exists<MeleeEscrow<Coin0, LP0, Coin1, LP1>>(swapper_address)) {
             return;
@@ -422,19 +423,17 @@ module arena::emojicoin_arena {
     }
 
     fun init_module(arena: &signer) {
-        // Get first melee market addresses, without using randomness APIs.
+        // Use pseudo-randomness to get market IDs for the first melee, since randomness is not
+        // supported during `init_module`.
         let time = timestamp::now_microseconds();
         let n_markets = get_n_registered_markets();
-        let pseudo_random_market_id_0 = time % n_markets + 1;
-        let pseudo_random_market_id_1;
+        let market_id_0 = pseudo_random_market_id(n_markets);
+        let market_id_1;
         loop {
-            pseudo_random_market_id_1 = psuedo_random_u64(time) % n_markets + 1;
-            if (pseudo_random_market_id_1 != pseudo_random_market_id_0) break;
+            market_id_1 = pseudo_random_market_id(n_markets);
+            if (market_id_1 != market_id_0) break;
         };
-        let market_ids =
-            sort_unique_market_ids(
-                pseudo_random_market_id_0, pseudo_random_market_id_1
-            );
+        let market_ids = sort_unique_market_ids(market_id_0, market_id_1);
 
         // Initialize first melee.
         let start_time =
@@ -455,19 +454,15 @@ module arena::emojicoin_arena {
                 duration: MELEE_DURATION_HOURS * MICROSECONDS_PER_HOUR
             }
         );
-        let melees_by_market_combo_sorted_market_ids = smart_table::new();
-        melees_by_market_combo_sorted_market_ids.add(market_ids, 1);
+        let melee_ids_by_market_ids = smart_table::new();
+        melee_ids_by_market_ids.add(market_ids, 1);
 
         // Store registry resource.
         let (vault_signer, signer_capability) =
             account::create_resource_account(arena, REGISTRY_SEED);
         move_to(
             arena,
-            Registry {
-                melees_by_id,
-                melees_by_market_combo_sorted_market_ids,
-                signer_capability
-            }
+            Registry { melees_by_id, melee_ids_by_market_ids, signer_capability }
         );
         coin::register<AptosCoin>(&vault_signer);
     }
@@ -547,9 +542,7 @@ module arena::emojicoin_arena {
                     duration: MELEE_DURATION_HOURS * MICROSECONDS_PER_HOUR
                 }
             );
-            registry_ref_mut.melees_by_market_combo_sorted_market_ids.add(
-                market_ids, melee_id
-            );
+            registry_ref_mut.melee_ids_by_market_ids.add(market_ids, melee_id);
             true
         } else false
     }
@@ -568,24 +561,20 @@ module arena::emojicoin_arena {
         let n_markets = get_n_registered_markets();
         let market_ids;
         loop {
-            let random_market_id_0 = random_market_id(n_markets);
-            let random_market_id_1 = random_market_id(n_markets);
-            if (random_market_id_0 == random_market_id_1) continue;
-            market_ids = sort_unique_market_ids(random_market_id_0, random_market_id_1);
-            if (!Registry[@arena].melees_by_market_combo_sorted_market_ids.contains(market_ids)) {
+            let market_id_0 = random_market_id(n_markets);
+            let market_id_1 = random_market_id(n_markets);
+            if (market_id_0 == market_id_1) continue;
+            market_ids = sort_unique_market_ids(market_id_0, market_id_1);
+            if (!Registry[@arena].melee_ids_by_market_ids.contains(market_ids))
                 break;
-            }
         };
         market_ids
 
     }
 
-    /// Psuedo random number generator based on xorshift64 algorithm from Wikipedia.
-    inline fun psuedo_random_u64(seed: u64): u64 {
-        seed = seed ^ (seed << 13);
-        seed = seed ^ (seed >> 7);
-        seed = seed ^ (seed << 17);
-        seed
+    /// Pseudo-random proxy for `random_market_id` for use during `init_module`.
+    inline fun pseudo_random_market_id(n_markets: u64): u64 {
+        pseudo_randomness::u64_range(0, n_markets) + 1
     }
 
     /// Market IDs are 1-indexed.

src/move/emojicoin_arena/sources/pseudo_randomness.move

@@ -2,10 +2,32 @@ module arena::pseudo_randomness {
 
     use aptos_framework::transaction_context;
     use std::bcs;
+    use std::vector;
+
+    friend arena::emojicoin_arena;
+
+    /// Pseudo-random proxy for `aptos_framework::randomness::u64_range`.
+    public(friend) inline fun u64_range(min_incl: u64, max_excl: u64): u64 {
+        let range = ((max_excl - min_incl) as u256);
+        let sample = ((u256_integer() % range) as u64);
+
+        min_incl + sample
+    }
 
     /// Pseudo-random proxy for `aptos_framework::randomness::next_32_bytes`.
     inline fun next_32_bytes(): vector<u8> {
-        bcs::to_bytes(transaction_context::generate_auid_address())
+        bcs::to_bytes(&transaction_context::generate_auid_address())
     }
 
-}
+    /// Pseudo-random proxy for `aptos_framework::randomness::u256_integer`.
+    inline fun u256_integer(): u256 {
+        let raw = next_32_bytes();
+        let i = 0;
+        let ret: u256 = 0;
+        while (i < 32) {
+            ret = ret * 256 + (vector::pop_back(&mut raw) as u256);
+            i = i + 1;
+        };
+        ret
+    }
+}