From ef535165f97d64dc643babb3ea593067bbf4fe95 Mon Sep 17 00:00:00 2001
From: Aryaman Jain <arjain@jumptrading.com>
Date: Wed, 15 May 2024 17:35:03 +0000
Subject: [PATCH] flamenco: add instrs reset to txn generation

---
 src/flamenco/txn/fd_txn_generate.c | 14 ++++++++++++++
 src/flamenco/txn/fd_txn_generate.h |  6 ++++++
 2 files changed, 20 insertions(+)

diff --git a/src/flamenco/txn/fd_txn_generate.c b/src/flamenco/txn/fd_txn_generate.c
index 39816e51c0..0628fbe35b 100644
--- a/src/flamenco/txn/fd_txn_generate.c
+++ b/src/flamenco/txn/fd_txn_generate.c
@@ -142,3 +142,17 @@ fd_txn_add_instr( uchar * txn_meta_ptr,
                                       data_sz, acct_off, data_off );
   return (ulong)(write_ptr - out_txn_payload);
 }
+
+void
+fd_txn_reset_instrs( uchar * txn_meta_ptr,
+                     uchar out_txn_payload[ static FD_TXN_MTU ] ) {
+  fd_txn_t * txn_meta = (fd_txn_t *)txn_meta_ptr;
+  ulong instr_start   = txn_meta->recent_blockhash_off + FD_TXN_BLOCKHASH_SZ;
+
+  ushort num_instrs   = txn_meta->instr_cnt;
+  ulong instrs_sz     = txn_meta->instr[num_instrs-1].data_off + txn_meta->instr[num_instrs-1].data_sz - instr_start;
+
+  fd_memset( (out_txn_payload + instr_start), 0UL, instrs_sz );
+  fd_memset( txn_meta->instr, 0UL, num_instrs * sizeof(fd_txn_instr_t) );
+  txn_meta->instr_cnt = 0;
+}
diff --git a/src/flamenco/txn/fd_txn_generate.h b/src/flamenco/txn/fd_txn_generate.h
index d7a107c90c..76496166b9 100644
--- a/src/flamenco/txn/fd_txn_generate.h
+++ b/src/flamenco/txn/fd_txn_generate.h
@@ -46,4 +46,10 @@ fd_txn_add_instr( uchar * txn_meta_ptr,
                   ulong accounts_sz,
                   uchar const * instr_buf,
                   ulong instr_buf_sz );
+
+/* Helper method to reset the list of instrs in the metadata and
+   remove all instrs from the txn payload. */
+void
+fd_txn_reset_instrs( uchar * txn_meta_ptr,
+                     uchar out_txn_payload[ static FD_TXN_MTU ] );
 FD_PROTOTYPES_END