flamenco: slot ctx in txn ctx is const

src/flamenco/runtime/context/fd_exec_instr_ctx.h

@@ -13,7 +13,7 @@ struct __attribute__((aligned(8UL))) fd_exec_instr_ctx {
   ulong magic; /* ==FD_EXEC_INSTR_CTX_MAGIC */
 
   fd_exec_epoch_ctx_t const * epoch_ctx;
-  fd_exec_slot_ctx_t *        slot_ctx; /* TODO: needs to be made const to be thread safe. */
+  fd_exec_slot_ctx_t const *  slot_ctx; /* TODO: needs to be made const to be thread safe. */
   fd_exec_txn_ctx_t *         txn_ctx;  /* The transaction context for this instruction */
 
   fd_exec_instr_ctx_t const * parent;

src/flamenco/runtime/context/fd_exec_txn_ctx.c

@@ -201,6 +201,7 @@ fd_exec_txn_ctx_setup( fd_exec_txn_ctx_t   * txn_ctx,
   txn_ctx->heap_size          = FD_VM_HEAP_DEFAULT;
   txn_ctx->loaded_accounts_data_size_limit = FD_VM_LOADED_ACCOUNTS_DATA_SIZE_LIMIT;
   txn_ctx->accounts_resize_delta = 0;
+  txn_ctx->collected_rent     = 0UL;
 
   txn_ctx->txn_descriptor = txn_descriptor;
   txn_ctx->_txn_raw->raw = txn_raw->raw;

src/flamenco/runtime/context/fd_exec_txn_ctx.h

@@ -58,7 +58,7 @@ struct __attribute__((aligned(8UL))) fd_exec_txn_ctx {
   ulong magic; /* ==FD_EXEC_TXN_CTX_MAGIC */
 
   fd_exec_epoch_ctx_t const * epoch_ctx;
-  fd_exec_slot_ctx_t *        slot_ctx;
+  fd_exec_slot_ctx_t const *  slot_ctx;
 
   fd_funk_txn_t *       funk_txn;
   fd_acc_mgr_t *        acc_mgr;
@@ -92,6 +92,7 @@ struct __attribute__((aligned(8UL))) fd_exec_txn_ctx {
   fd_hash_t             blake_txn_msg_hash;                          /* Hash of raw transaction message used by the status cache */
   ulong                 execution_fee;                               /* Execution fee paid by the fee payer in the transaction */
   ulong                 priority_fee;                                /* Priority fee paid by the fee payer in the transaction */
+  ulong                 collected_rent;                              /* Rent collected from accounts in this transaction */
 
   uchar dirty_vote_acc  : 1;                                         /* 1 if this transaction maybe modified a vote account */
   uchar dirty_stake_acc : 1;                                         /* 1 if this transaction maybe modified a stake account */

src/flamenco/runtime/fd_executor.c

@@ -247,7 +247,7 @@ fd_executor_check_status_cache( fd_exec_txn_ctx_t * txn_ctx ) {
 
   // TODO: figure out if it is faster to batch query properly and loop all txns again
   int err;
-  fd_txncache_query_batch( txn_ctx->slot_ctx->status_cache, &curr_query, 1UL, txn_ctx->slot_ctx, status_check_tower, &err );
+  fd_txncache_query_batch( txn_ctx->slot_ctx->status_cache, &curr_query, 1UL, (void *)txn_ctx->slot_ctx, status_check_tower, &err );
   return err;
 }
 
@@ -359,7 +359,7 @@ fd_executor_load_transaction_accounts( fd_exec_txn_ctx_t * txn_ctx ) {
        TODO: the rent epoch check in the conditional should probably be moved
        to inside fd_runtime_collect_rent_from_account. */
     if( fd_txn_account_is_writable_idx( txn_ctx, (int)i ) && acct->const_meta->info.rent_epoch<=epoch ) {
-      fd_runtime_collect_rent_from_account( txn_ctx->slot_ctx, acct->meta, acct->pubkey, epoch );
+      txn_ctx->collected_rent += fd_runtime_collect_rent_from_account( txn_ctx->slot_ctx, acct->meta, acct->pubkey, epoch );
       acct->starting_lamports = acct->meta->info.lamports;
     }
 
@@ -519,8 +519,8 @@ fd_executor_validate_account_locks( fd_exec_txn_ctx_t const * txn_ctx ) {
 
 /* https://github.com/anza-xyz/agave/blob/89050f3cb7e76d9e273f10bea5e8207f2452f79f/svm/src/account_loader.rs#L101-L126 */
 static int
-fd_should_set_exempt_rent_epoch_max( fd_exec_slot_ctx_t *        slot_ctx,
-                                     fd_borrowed_account_t *     rec ) {
+fd_should_set_exempt_rent_epoch_max( fd_exec_slot_ctx_t const * slot_ctx,
+                                     fd_borrowed_account_t *    rec ) {
   /* https://github.com/anza-xyz/agave/blob/89050f3cb7e76d9e273f10bea5e8207f2452f79f/svm/src/account_loader.rs#L109-L125 */
   if( FD_FEATURE_ACTIVE( slot_ctx, disable_rent_fees_collection ) ) {
     if( FD_LIKELY( rec->const_meta->info.rent_epoch!=ULONG_MAX
@@ -620,7 +620,7 @@ fd_executor_validate_transaction_fee_payer( fd_exec_txn_ctx_t * txn_ctx ) {
      https://github.com/anza-xyz/agave/blob/16de8b75ebcd57022409b422de557dd37b1de8db/svm/src/transaction_processor.rs#L438-L445 */
   fd_epoch_schedule_t const * schedule = fd_sysvar_cache_epoch_schedule( txn_ctx->slot_ctx->sysvar_cache );
   ulong                       epoch    = fd_slot_to_epoch( schedule, txn_ctx->slot_ctx->slot_bank.slot, NULL );
-  fd_runtime_collect_rent_from_account( txn_ctx->slot_ctx, fee_payer_rec->meta, fee_payer_rec->pubkey, epoch );
+  txn_ctx->collected_rent += fd_runtime_collect_rent_from_account( txn_ctx->slot_ctx, fee_payer_rec->meta, fee_payer_rec->pubkey, epoch );
   fee_payer_rec->starting_lamports = fee_payer_rec->meta->info.lamports;
 
   /* https://github.com/anza-xyz/agave/blob/16de8b75ebcd57022409b422de557dd37b1de8db/svm/src/transaction_processor.rs#L431-L488 */
@@ -1412,7 +1412,7 @@ create_txn_context_protobuf_from_txn( fd_exec_test_txn_context_t * txn_context_m
                                       fd_spad_t *                  spad ) {
   fd_txn_t const * txn_descriptor = txn_ctx->txn_descriptor;
   uchar const * txn_payload = (uchar const *) txn_ctx->_txn_raw->raw;
-  fd_exec_slot_ctx_t * slot_ctx = txn_ctx->slot_ctx;
+  fd_exec_slot_ctx_t const * slot_ctx = txn_ctx->slot_ctx;
 
   /* We don't want to store builtins in account shared data */
   fd_pubkey_t const loaded_builtins[] = {
@@ -1676,7 +1676,7 @@ create_txn_context_protobuf_from_txn( fd_exec_test_txn_context_t * txn_context_m
   txn_context_msg->blockhash_queue = output_blockhash_queue;
 
   // Iterate over all block hashes in the queue and save them
-  fd_block_hash_queue_t * queue = &slot_ctx->slot_bank.block_hash_queue;
+  fd_block_hash_queue_t const * queue = &slot_ctx->slot_bank.block_hash_queue;
   fd_hash_hash_age_pair_t_mapnode_t * nn;
   for ( fd_hash_hash_age_pair_t_mapnode_t * n = fd_hash_hash_age_pair_t_map_minimum( queue->ages_pool, queue->ages_root ); n; n = nn ) {
     nn = fd_hash_hash_age_pair_t_map_successor( queue->ages_pool, n );
@@ -1895,7 +1895,9 @@ fd_execute_txn( fd_exec_txn_ctx_t * txn_ctx ) {
   } FD_SCRATCH_SCOPE_END;
 }
 
-int fd_executor_txn_check( fd_exec_slot_ctx_t * slot_ctx,  fd_exec_txn_ctx_t *txn ) {
+int
+fd_executor_txn_check( fd_exec_slot_ctx_t const * slot_ctx,
+                       fd_exec_txn_ctx_t *        txn ) {
   fd_rent_t const * rent = fd_sysvar_cache_rent( slot_ctx->sysvar_cache );
 
   ulong starting_lamports_l = 0;

src/flamenco/runtime/fd_executor.h

@@ -111,7 +111,8 @@ fd_executor_is_system_nonce_account( fd_borrowed_account_t * account );
  */
 
 int
-fd_executor_txn_check( fd_exec_slot_ctx_t * slot_ctx,  fd_exec_txn_ctx_t *txn );
+fd_executor_txn_check( fd_exec_slot_ctx_t const * slot_ctx, 
+                       fd_exec_txn_ctx_t *        txn );
 
 void
 fd_txn_reclaim_accounts( fd_exec_txn_ctx_t * txn_ctx );

src/flamenco/runtime/fd_runtime.c

@@ -1086,6 +1086,14 @@ fd_txn_prep_and_exec_task( void  *tpool,
     FD_COMPILER_MFENCE();
   }
 
+  curr = slot_ctx->slot_bank.collected_rent;
+  FD_COMPILER_MFENCE();
+  while( FD_UNLIKELY( FD_ATOMIC_CAS( &slot_ctx->slot_bank.collected_rent, curr, curr + task_info->txn_ctx->collected_rent ) != curr ) ) {
+    FD_SPIN_PAUSE();
+    curr = slot_ctx->slot_bank.collected_rent;
+    FD_COMPILER_MFENCE();
+  }
+
   // fd_runtime_finalize_txn( slot_ctx, capture_ctx, task_info );
 
 }
@@ -1170,6 +1178,14 @@ fd_runtime_prepare_execute_finalize_txn( fd_exec_slot_ctx_t *         slot_ctx,
     FD_COMPILER_MFENCE();
   }
 
+  curr = slot_ctx->slot_bank.collected_rent;
+  FD_COMPILER_MFENCE();
+  while( FD_UNLIKELY( FD_ATOMIC_CAS( &slot_ctx->slot_bank.collected_rent, curr, curr + task_info->txn_ctx->collected_rent ) != curr ) ) {
+    FD_SPIN_PAUSE();
+    curr = slot_ctx->slot_bank.collected_rent;
+    FD_COMPILER_MFENCE();
+  }
+
   fd_runtime_finalize_txn( slot_ctx, capture_ctx, task_info );
 
   return res;
@@ -3191,7 +3207,9 @@ fd_runtime_calculate_fee(fd_exec_txn_ctx_t *txn_ctx,
 #define FD_RENT_EXEMPT (-1L)
 
 static long
-fd_runtime_get_rent_due( fd_exec_slot_ctx_t * slot_ctx, fd_account_meta_t * acc, ulong epoch ) {
+fd_runtime_get_rent_due( fd_exec_slot_ctx_t const * slot_ctx,
+                         fd_account_meta_t *        acc,
+                         ulong                      epoch ) {
 
   fd_epoch_bank_t     * epoch_bank     = fd_exec_epoch_ctx_epoch_bank( slot_ctx->epoch_ctx );
   fd_epoch_schedule_t * schedule       = &epoch_bank->rent_epoch_schedule;
@@ -3237,11 +3255,13 @@ fd_runtime_get_rent_due( fd_exec_slot_ctx_t * slot_ctx, fd_account_meta_t * acc,
 }
 
 /* https://github.com/anza-xyz/agave/blob/v2.0.10/sdk/src/rent_collector.rs#L117-149 */
-void
-fd_runtime_collect_from_existing_account( fd_exec_slot_ctx_t * slot_ctx,
-                                          fd_account_meta_t  * acc,
-                                          fd_pubkey_t const  * pubkey,
-                                          ulong                epoch ) {
+/* Collect rent from an account. Returns the amount of rent collected. */
+ulong
+fd_runtime_collect_from_existing_account( fd_exec_slot_ctx_t const * slot_ctx,
+                                          fd_account_meta_t *        acc,
+                                          fd_pubkey_t const *        pubkey,
+                                          ulong                      epoch ) {
+  ulong collected_rent = 0UL;
   #define NO_RENT_COLLECTION_NOW (-1)
   #define EXEMPT                 (-2)
   #define COLLECT_RENT           (-3)
@@ -3287,17 +3307,18 @@ fd_runtime_collect_from_existing_account( fd_exec_slot_ctx_t * slot_ctx,
     case COLLECT_RENT:
       if( FD_UNLIKELY( (ulong)rent_due>=acc->info.lamports ) ) {
         /* Reclaim account */
-        slot_ctx->slot_bank.collected_rent += (ulong)acc->info.lamports;
+        collected_rent += (ulong)acc->info.lamports;
         acc->info.lamports                  = 0UL;
         acc->dlen                           = 0UL;
         fd_memset( acc->info.owner, 0, sizeof(acc->info.owner) );
       } else {
-        slot_ctx->slot_bank.collected_rent += (ulong)rent_due;
+        collected_rent += (ulong)rent_due;
         acc->info.lamports                 -= (ulong)rent_due;
         acc->info.rent_epoch                = epoch+1UL;
       }
   }
 
+  return collected_rent;
 
   #undef NO_RENT_COLLECTION_NOW
   #undef EXEMPT
@@ -3308,24 +3329,23 @@ fd_runtime_collect_from_existing_account( fd_exec_slot_ctx_t * slot_ctx,
    Although the Solana runtime prevents the creation of new accounts
    that are subject to rent, some older accounts are still undergo the
    rent collection process.  Updates the account's 'rent_epoch' if
-   needed. Returns 1 if the account was changed, and 0 if it is
-   unchanged. */
+   needed. Returns the amount of rent collected. */
 /* https://github.com/anza-xyz/agave/blob/v2.0.10/svm/src/account_loader.rs#L71-96 */
-int
-fd_runtime_collect_rent_from_account( fd_exec_slot_ctx_t *  slot_ctx,
-                                      fd_account_meta_t  *  acc,
-                                      fd_pubkey_t const  *  key,
-                                      ulong                 epoch ) {
+ulong
+fd_runtime_collect_rent_from_account( fd_exec_slot_ctx_t const * slot_ctx,
+                                      fd_account_meta_t *        acc,
+                                      fd_pubkey_t const *        key,
+                                      ulong                      epoch ) {
 
   if( !FD_FEATURE_ACTIVE( slot_ctx, disable_rent_fees_collection ) ) {
-    fd_runtime_collect_from_existing_account( slot_ctx, acc, key, epoch );
+    return fd_runtime_collect_from_existing_account( slot_ctx, acc, key, epoch );
   } else {
     if( FD_UNLIKELY( acc->info.rent_epoch!=FD_RENT_EXEMPT_RENT_EPOCH &&
                      fd_runtime_get_rent_due( slot_ctx, acc, epoch )==FD_RENT_EXEMPT ) ) {
       acc->info.rent_epoch = ULONG_MAX;
     }
   }
-  return FD_RUNTIME_EXECUTE_SUCCESS;
+  return 0UL;
 }
 
 static void
@@ -3377,7 +3397,7 @@ fd_runtime_collect_rent_for_slot( fd_exec_slot_ctx_t * slot_ctx, ulong off, ulon
     }
 
     /* Actually invoke rent collection */
-    fd_runtime_collect_rent_from_account( slot_ctx, rec->meta, key, epoch );
+    slot_ctx->slot_bank.collected_rent += fd_runtime_collect_rent_from_account( slot_ctx, rec->meta, key, epoch );
   }
 }
 

src/flamenco/runtime/fd_runtime.h

@@ -230,11 +230,11 @@ fd_runtime_block_execute_finalize_tpool( fd_exec_slot_ctx_t * slot_ctx,
                                          fd_block_info_t const * block_info,
                                          fd_tpool_t * tpool );
 
-int
-fd_runtime_collect_rent_from_account( fd_exec_slot_ctx_t * slot_ctx,
-                                      fd_account_meta_t  * acc,
-                                      fd_pubkey_t const  * key,
-                                      ulong                epoch );
+ulong
+fd_runtime_collect_rent_from_account( fd_exec_slot_ctx_t const * slot_ctx,
+                                      fd_account_meta_t  *       acc,
+                                      fd_pubkey_t const  *       key,
+                                      ulong                      epoch );
 
 void
 fd_runtime_execute_txn( fd_execute_txn_task_info_t * task_info );

src/flamenco/runtime/program/fd_bpf_program_util.c

@@ -432,7 +432,7 @@ fd_bpf_check_and_create_bpf_program_cache_entry( fd_exec_slot_ctx_t * slot_ctx,
 }
 
 int
-fd_bpf_load_cache_entry( fd_exec_slot_ctx_t *           slot_ctx,
+fd_bpf_load_cache_entry( fd_exec_slot_ctx_t const *     slot_ctx,
                          fd_pubkey_t const *            program_pubkey,
                          fd_sbpf_validated_program_t ** valid_prog ) {
   fd_funk_t * funk = slot_ctx->acc_mgr->funk;
@@ -465,8 +465,8 @@ fd_bpf_add_to_program_blacklist( fd_exec_slot_ctx_t * slot_ctx,
 }
 
 int
-fd_bpf_is_in_program_blacklist( fd_exec_slot_ctx_t * slot_ctx,
-                                fd_pubkey_t const  * program_pubkey ) {
+fd_bpf_is_in_program_blacklist( fd_exec_slot_ctx_t const * slot_ctx,
+                                fd_pubkey_t const *        program_pubkey ) {
 
   for( uint i=0U; i<slot_ctx->program_blacklist_cnt; i++ ) {
     if( FD_UNLIKELY( !memcmp( &slot_ctx->program_blacklist[i], program_pubkey, sizeof(fd_pubkey_t) ) ) ) {

src/flamenco/runtime/program/fd_bpf_program_util.h

@@ -64,7 +64,7 @@ fd_bpf_scan_and_create_bpf_program_cache_entry_tpool( fd_exec_slot_ctx_t * slot_
                                                       int                  update_program_blacklist );
 
 int
-fd_bpf_load_cache_entry( fd_exec_slot_ctx_t *           slot_ctx,
+fd_bpf_load_cache_entry( fd_exec_slot_ctx_t const *     slot_ctx,
                          fd_pubkey_t const *            program_pubkey,
                          fd_sbpf_validated_program_t ** valid_prog );
 
@@ -87,7 +87,7 @@ fd_bpf_add_to_program_blacklist( fd_exec_slot_ctx_t * slot_ctx,
                                  fd_pubkey_t const  * program_pubkey );
 
 int
-fd_bpf_is_in_program_blacklist( fd_exec_slot_ctx_t * slot_ctx, 
+fd_bpf_is_in_program_blacklist( fd_exec_slot_ctx_t const * slot_ctx, 
                                 fd_pubkey_t const  * program_pubkey );
 
 FD_PROTOTYPES_END

src/flamenco/runtime/program/fd_stake_program.c

@@ -183,7 +183,7 @@ set_state( fd_exec_instr_ctx_t const * ctx,
 
 // https://github.com/anza-xyz/agave/blob/c8685ce0e1bb9b26014f1024de2cd2b8c308cbde/programs/stake/src/lib.rs#L29
 static inline ulong
-get_minimum_delegation( fd_exec_slot_ctx_t * slot_ctx /* feature set */ ) {
+get_minimum_delegation( fd_exec_slot_ctx_t const * slot_ctx /* feature set */ ) {
   return fd_ulong_if( FD_FEATURE_ACTIVE( slot_ctx, stake_raise_minimum_delegation_to_1_sol ),
                       MINIMUM_DELEGATION_SOL * LAMPORTS_PER_SOL,
                       1 );
@@ -215,7 +215,7 @@ typedef struct validated_delegated_info validated_delegated_info_t;
 static int
 validate_delegated_amount( fd_borrowed_account_t *      account,
                            fd_stake_meta_t const *      meta,
-                           fd_exec_slot_ctx_t *         slot_ctx,
+                           fd_exec_slot_ctx_t const *   slot_ctx,
                            validated_delegated_info_t * out,
                            uint *                       custom_err ) {
   ulong stake_amount = fd_ulong_sat_sub( account->const_meta->info.lamports, meta->rent_exempt_reserve );

src/flamenco/runtime/sysvar/fd_sysvar_clock.c

@@ -48,8 +48,8 @@ write_clock( fd_exec_slot_ctx_t *    slot_ctx,
 
 
 fd_sol_sysvar_clock_t *
-fd_sysvar_clock_read( fd_sol_sysvar_clock_t * result,
-                      fd_exec_slot_ctx_t *    slot_ctx  ) {
+fd_sysvar_clock_read( fd_sol_sysvar_clock_t *    result,
+                      fd_exec_slot_ctx_t const * slot_ctx  ) {
   fd_sol_sysvar_clock_t const * ret = fd_sysvar_cache_clock( slot_ctx->sysvar_cache );
   if( NULL != ret ) {
     fd_memcpy(result, ret, sizeof(fd_sol_sysvar_clock_t));

src/flamenco/runtime/sysvar/fd_sysvar_clock.h

@@ -28,8 +28,8 @@ fd_sysvar_clock_update( fd_exec_slot_ctx_t * slot_ctx );
 /* Reads the current value of the clock sysvar */
 
 fd_sol_sysvar_clock_t *
-fd_sysvar_clock_read( fd_sol_sysvar_clock_t * result,
-                      fd_exec_slot_ctx_t *    slot_ctx );
+fd_sysvar_clock_read( fd_sol_sysvar_clock_t *    result,
+                      fd_exec_slot_ctx_t const * slot_ctx );
 
 /* fd_slot_cnt_2day returns the number of slots in two days.
    Used in rent collection. */

src/flamenco/runtime/sysvar/fd_sysvar_epoch_schedule.c

@@ -50,8 +50,8 @@ write_epoch_schedule( fd_exec_slot_ctx_t  * slot_ctx,
 }
 
 fd_epoch_schedule_t *
-fd_sysvar_epoch_schedule_read( fd_epoch_schedule_t * result,
-                               fd_exec_slot_ctx_t  * slot_ctx ) {
+fd_sysvar_epoch_schedule_read( fd_epoch_schedule_t *      result,
+                               fd_exec_slot_ctx_t const * slot_ctx ) {
   fd_epoch_schedule_t const * ret = fd_sysvar_cache_epoch_schedule( slot_ctx->sysvar_cache );
   if( FD_UNLIKELY( NULL != ret ) ) {
     fd_memcpy(result, ret, sizeof(fd_epoch_schedule_t));

src/flamenco/runtime/sysvar/fd_sysvar_epoch_schedule.h

@@ -65,7 +65,7 @@ fd_sysvar_epoch_schedule_init( fd_exec_slot_ctx_t * slot_ctx );
 
 fd_epoch_schedule_t *
 fd_sysvar_epoch_schedule_read( fd_epoch_schedule_t * result,
-                               fd_exec_slot_ctx_t *  slot_ctx );
+                               fd_exec_slot_ctx_t const * slot_ctx );
 
 /* fd_epoch_schedule_derive derives an epoch schedule config from the
    given parameters.  New epoch schedule configurations should only be

src/flamenco/runtime/sysvar/fd_sysvar_fees.c

@@ -19,8 +19,8 @@ write_fees( fd_exec_slot_ctx_t* slot_ctx, fd_sysvar_fees_t* fees ) {
 }
 
 fd_sysvar_fees_t *
-fd_sysvar_fees_read( fd_sysvar_fees_t * result,
-                     fd_exec_slot_ctx_t * slot_ctx ) {
+fd_sysvar_fees_read( fd_sysvar_fees_t *         result,
+                     fd_exec_slot_ctx_t const * slot_ctx ) {
   fd_sysvar_fees_t const * ret = fd_sysvar_cache_fees( slot_ctx->sysvar_cache );
   if( FD_UNLIKELY( NULL != ret ) ) {
     fd_memcpy(result, ret, sizeof(fd_sysvar_fees_t));

src/flamenco/runtime/sysvar/fd_sysvar_fees.h

@@ -14,8 +14,8 @@ fd_sysvar_fees_init( fd_exec_slot_ctx_t * slot_ctx );
 
 /* Reads the current value of the fees sysvar */
 fd_sysvar_fees_t *
-fd_sysvar_fees_read( fd_sysvar_fees_t *   result,
-                     fd_exec_slot_ctx_t * slot_ctx );
+fd_sysvar_fees_read( fd_sysvar_fees_t *         result,
+                     fd_exec_slot_ctx_t const * slot_ctx );
 
 void
 fd_sysvar_fees_new_derived( fd_exec_slot_ctx_t *   slot_ctx,

src/flamenco/runtime/sysvar/fd_sysvar_rent.c

@@ -9,8 +9,8 @@
 #define ACCOUNT_STORAGE_OVERHEAD (128)
 
 fd_rent_t *
-fd_sysvar_rent_read( fd_rent_t *          result,
-                     fd_exec_slot_ctx_t * slot_ctx ) {
+fd_sysvar_rent_read( fd_rent_t *                result,
+                     fd_exec_slot_ctx_t const * slot_ctx ) {
 
   fd_rent_t const * ret = fd_sysvar_cache_rent( slot_ctx->sysvar_cache );
   if( FD_UNLIKELY( NULL != ret ) ) {

src/flamenco/runtime/sysvar/fd_sysvar_rent.h

@@ -19,8 +19,8 @@ fd_sysvar_rent_init( fd_exec_slot_ctx_t * slot_ctx );
    Returns result on success, NULL otherwise. */
 
 fd_rent_t *
-fd_sysvar_rent_read( fd_rent_t *          result,
-                     fd_exec_slot_ctx_t * slot_ctx );
+fd_sysvar_rent_read( fd_rent_t *                result,
+                     fd_exec_slot_ctx_t const * slot_ctx );
 
 /* fd_rent_exempt_minimum_balance returns the minimum balance needed
    for an account with the given data_len to be rent exempt.  rent