From ee50f06a3e66862a89e546fab01aa579a07877cd Mon Sep 17 00:00:00 2001
From: Adam Spitz <adamspitz@status.im>
Date: Mon, 13 Mar 2023 14:18:30 -0400
Subject: [PATCH] Sketching in "stateless mode". (#1495)

(Doesn't do anything yet.)
---
 nimbus/config.nim         | 10 ++++++----
 nimbus/nimbus.nim         | 12 ++++++++++--
 nimbus/sync/stateless.nim | 41 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 57 insertions(+), 6 deletions(-)
 create mode 100644 nimbus/sync/stateless.nim

diff --git a/nimbus/config.nim b/nimbus/config.nim
index b0b8325c4..52717e5d4 100644
--- a/nimbus/config.nim
+++ b/nimbus/config.nim
@@ -140,6 +140,7 @@ type
     Full                          ## Beware, experimental
     Snap                          ## Beware, experimental
     SnapCtx                       ## Beware, experimental
+    Stateless                     ## Beware, experimental
 
   NimbusConf* = object of RootObj
     ## Main Nimbus configuration object
@@ -169,10 +170,11 @@ type
     syncMode* {.
       desc: "Specify particular blockchain sync mode."
       longDesc:
-        "- default -- legacy sync mode\n" &
-        "- full    -- full blockchain archive\n" &
-        "- snap    -- experimental snap mode (development only)\n" &
-        "- snapCtx -- snap considering possible recovery context"
+        "- default   -- legacy sync mode\n" &
+        "- full      -- full blockchain archive\n" &
+        "- snap      -- experimental snap mode (development only)\n" &
+        "- snapCtx   -- snap considering possible recovery context\n" &
+        "- stateless -- experimental stateless mode (development only)"
       defaultValue: SyncMode.Default
       defaultValueDesc: $SyncMode.Default
       abbr: "y"
diff --git a/nimbus/nimbus.nim b/nimbus/nimbus.nim
index 1ddab3390..646962999 100644
--- a/nimbus/nimbus.nim
+++ b/nimbus/nimbus.nim
@@ -27,7 +27,7 @@ import
   ./core/[chain, sealer, clique/clique_desc,
     clique/clique_sealer, tx_pool, block_import],
   ./rpc/merge/merger,
-  ./sync/[legacy, full, protocol, snap,
+  ./sync/[legacy, full, protocol, snap, stateless,
     protocol/les_protocol, handlers, peers]
 
 when defined(evmc_enabled):
@@ -60,6 +60,7 @@ type
     legaSyncRef: LegacySyncRef
     snapSyncRef: SnapSyncRef
     fullSyncRef: FullSyncRef
+    statelessSyncRef: StatelessSyncRef
     merger: MergerRef
 
 proc importBlocks(conf: NimbusConf, com: CommonRef) =
@@ -186,6 +187,9 @@ proc setupP2P(nimbus: NimbusNode, conf: NimbusConf,
       nimbus.snapSyncRef = SnapSyncRef.init(
         nimbus.ethNode, nimbus.chainRef, nimbus.ctx.rng, conf.maxPeers,
         nimbus.dbBackend, tickerOK, noRecovery=noRecovery, exCtrlFile)
+    of SyncMode.Stateless:
+      # FIXME-Adam: what needs to go here?
+      nimbus.statelessSyncRef = StatelessSyncRef.init()
     of SyncMode.Default:
       nimbus.legaSyncRef = LegacySyncRef.new(
         nimbus.ethNode, nimbus.chainRef)
@@ -205,7 +209,7 @@ proc setupP2P(nimbus: NimbusNode, conf: NimbusConf,
   if conf.maxPeers > 0:
     var waitForPeers = true
     case conf.syncMode:
-    of SyncMode.Snap, SyncMode.SnapCtx:
+    of SyncMode.Snap, SyncMode.SnapCtx, SyncMode.Stateless:
       waitForPeers = false
     of SyncMode.Full, SyncMode.Default:
       discard
@@ -428,6 +432,8 @@ proc start(nimbus: NimbusNode, conf: NimbusConf) =
           cast[pointer](nimbus.legaSyncRef))
       of SyncMode.Full:
         nimbus.fullSyncRef.start
+      of SyncMode.Stateless:
+        nimbus.statelessSyncRef.start
       of SyncMode.Snap, SyncMode.SnapCtx:
         nimbus.snapSyncRef.start
 
@@ -455,6 +461,8 @@ proc stop*(nimbus: NimbusNode, conf: NimbusConf) {.async, gcsafe.} =
     await nimbus.networkLoop.cancelAndWait()
   if nimbus.peerManager.isNil.not:
     await nimbus.peerManager.stop()
+  if nimbus.statelessSyncRef.isNil.not:
+    nimbus.statelessSyncRef.stop()
   if nimbus.snapSyncRef.isNil.not:
     nimbus.snapSyncRef.stop()
   if nimbus.fullSyncRef.isNil.not:
diff --git a/nimbus/sync/stateless.nim b/nimbus/sync/stateless.nim
new file mode 100644
index 000000000..7576607e7
--- /dev/null
+++ b/nimbus/sync/stateless.nim
@@ -0,0 +1,41 @@
+# Nimbus
+# Copyright (c) 2023 Status Research & Development GmbH
+# Licensed under either of
+#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
+#    http://www.apache.org/licenses/LICENSE-2.0)
+#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or
+#    http://opensource.org/licenses/MIT)
+# at your option. This file may not be copied, modified, or distributed
+# except according to those terms.
+
+{.push raises: [].}
+
+import
+  eth/[common, p2p],
+  chronicles,
+  chronos,
+  stew/[interval_set, sorted_set],
+  "."/[sync_desc, sync_sched, protocol]
+
+logScope:
+  topics = "stateless-sync"
+
+type
+  StatelessSyncRef* = ref object
+    # FIXME-Adam: what needs to go in here?
+
+    
+# ------------------------------------------------------------------------------
+# Public functions
+# ------------------------------------------------------------------------------
+
+proc init*(T: type StatelessSyncRef): T =
+  new result
+
+
+proc start*(ctx: StatelessSyncRef) =
+  # FIXME-Adam: What do I need here, if anything?
+  discard
+
+proc stop*(ctx: StatelessSyncRef) =
+  discard