From 7e64eb97b9c077f92e7f21327c63edc5c82dbc6d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Joaqu=C3=ADn=20Rosales?= <joaquin.rosales@iohk.io>
Date: Wed, 4 Dec 2024 18:30:23 -0600
Subject: [PATCH] wip(cat-gateway): add purge command when only one chain
 follower is left

---
 catalyst-gateway/bin/src/cardano/mod.rs       | 23 ++++++----
 .../bin/src/db/index/block/roll_forward.rs    | 42 +++++++++++++++++++
 2 files changed, 58 insertions(+), 7 deletions(-)

diff --git a/catalyst-gateway/bin/src/cardano/mod.rs b/catalyst-gateway/bin/src/cardano/mod.rs
index 41e775865f4..0f8e5e6384a 100644
--- a/catalyst-gateway/bin/src/cardano/mod.rs
+++ b/catalyst-gateway/bin/src/cardano/mod.rs
@@ -12,7 +12,7 @@ use tracing::{debug, error, info, warn};
 
 use crate::{
     db::index::{
-        block::index_block,
+        block::{index_block, roll_forward},
         queries::sync_status::{
             get::{get_sync_status, SyncStatus},
             update::update_sync_status,
@@ -451,12 +451,21 @@ impl SyncTask {
 
             // TODO: IF there is only 1 chain follower left in sync_tasks, then all
             // immutable followers have finished.
-            // When this happens we need to purge the live index of any records that exist
-            // before the current immutable tip.
-            // Note: to prevent a data race when multiple nodes are syncing, we probably
-            // want to put a gap in this, so that there are X slots of overlap
-            // between the live chain and immutable chain.  This gap should be
-            // a parameter.
+            // When this happens we need to purge the live index of any records that
+            // exist before the current immutable tip.
+            // Note: to prevent a data race when multiple nodes are syncing, we
+            // probably want to put a gap in this, so that there are X
+            // slots of overlap between the live chain and immutable
+            // chain.  This gap should be a parameter.
+
+            // WIP: How do we check that only one follower is left, and that the slot buffer
+            // (overlap) criteria is met?
+            let only_one_chain_follower_left = false;
+            if only_one_chain_follower_left {
+                if let Err(error) = roll_forward::purge_live_index(self.immutable_tip_slot).await {
+                    error!(chain=%self.cfg.chain, error=%error, "BUG: Purging volatile data task failed.");
+                }
+            }
         }
 
         error!(chain=%self.cfg.chain,"BUG: Sync tasks have all stopped.  This is an unexpected error!");
diff --git a/catalyst-gateway/bin/src/db/index/block/roll_forward.rs b/catalyst-gateway/bin/src/db/index/block/roll_forward.rs
index f0d23fd92c1..7e0c19d4733 100644
--- a/catalyst-gateway/bin/src/db/index/block/roll_forward.rs
+++ b/catalyst-gateway/bin/src/db/index/block/roll_forward.rs
@@ -1 +1,43 @@
 //! Immutable Roll Forward logic.
+
+use crate::{
+    db::index::{block::CassandraSession, queries::purge},
+    settings::Settings,
+};
+
+/// Purge Data from Live Index
+#[allow(unused_variables)]
+pub(crate) async fn purge_live_index(purge_slot: u64) -> anyhow::Result<()> {
+    let persistent = false; // get volatile session
+    let Some(session) = CassandraSession::get(persistent) else {
+        anyhow::bail!("Failed to acquire db session");
+    };
+
+    let chain_root_for_role0_keys =
+        purge::chain_root_for_role0_key::PrimaryKeyQuery::execute(&session).await?;
+    let chain_root_for_stake_address_keys =
+        purge::chain_root_for_stake_address::PrimaryKeyQuery::execute(&session).await?;
+    let chain_root_for_txn_id_keys =
+        purge::chain_root_for_txn_id::PrimaryKeyQuery::execute(&session).await?;
+    let cip36_registration_keys =
+        purge::cip36_registration::PrimaryKeyQuery::execute(&session).await?;
+    let cip36_registration_for_vote_keys =
+        purge::cip36_registration_for_vote_key::PrimaryKeyQuery::execute(&session).await?;
+    let cip36_registration_invalid_keys =
+        purge::cip36_registration_invalid::PrimaryKeyQuery::execute(&session).await?;
+    let rbac509_registration_keys =
+        purge::rbac509_registration::PrimaryKeyQuery::execute(&session).await?;
+    let stake_registration_keys =
+        purge::stake_registration::PrimaryKeyQuery::execute(&session).await?;
+    let txi_by_hash_keys = purge::txi_by_hash::PrimaryKeyQuery::execute(&session).await?;
+    let txo_ada_keys = purge::txo_ada::PrimaryKeyQuery::execute(&session).await?;
+    let txo_assets_keys = purge::txo_assets::PrimaryKeyQuery::execute(&session).await?;
+    let unstaked_txo_ada_keys = purge::unstaked_txo_ada::PrimaryKeyQuery::execute(&session).await?;
+    let unstaked_txo_assets_keys =
+        purge::unstaked_txo_assets::PrimaryKeyQuery::execute(&session).await?;
+
+    // WIP: delete filtered keys
+    // let purge_to_slot: u64 = purge_slot.saturating_sub(Settings::purge_slot_buffer());
+
+    Ok(())
+}