Halve FC memory usage

Blocks are getting stored both in BlockRef and in TxFrame - this is the
less invasive change that delays storing block contents in TxFrame until
it's time to update the base - the better option for the future is
likely to not store the full block in BlockRef (and instead load it from
TxFrame on demand)

Author: arnetheduck

execution_chain/core/chain/forked_chain.nim

@@ -315,6 +315,15 @@ proc updateBase(c: ForkedChainRef, base: BlockRef): uint =
     return
 
   let startTime = Moment.now()
+  block:
+    # Write block contents to txFrame at the last moment - otherwise, they would
+    # stay both in BlockRef and TxFrame memory
+    # TODO probably makes sense to do it the other way around, removing blk
+    #      from BlockRef
+    var blk = base
+    while blk.isOk:
+      c.writeBaggage(blk.blk, blk.hash, blk.txFrame, blk.receipts)
+      blk = blk.parent
 
   # State root sanity check is performed to verify, before writing to disk,
   # that optimistically checked blocks indeed end up being stored with a
@@ -513,7 +522,7 @@ proc validateBlock(c: ForkedChainRef,
   # Update the snapshot before processing the block so that any vertexes in snapshots
   # from lower levels than the baseTxFrame are removed from the snapshot before running
   # the stateroot computation.
-  c.updateSnapshot(parent.blk, parentFrame)
+  c.updateSnapshot(parent.blk.header.number, parentFrame)
 
   var receipts = c.processBlock(parent, txFrame, blk, blkHash, finalized).valueOr:
     txFrame.dispose()

execution_chain/core/chain/forked_chain/chain_private.nim

@@ -35,8 +35,8 @@ proc writeBaggage*(c: ForkedChainRef,
       header.withdrawalsRoot.expect("WithdrawalsRoot should be verified before"),
       blk.withdrawals.get)
 
-template updateSnapshot*(c: ForkedChainRef,
-            blk: Block,
+proc updateSnapshot*(c: ForkedChainRef,
+            number: BlockNumber,
             txFrame: CoreDbTxRef) =
   let pos = c.lastSnapshotPos
   c.lastSnapshotPos = (c.lastSnapshotPos + 1) mod c.lastSnapshots.len
@@ -51,7 +51,7 @@ template updateSnapshot*(c: ForkedChainRef,
   # Checkpoint creates a snapshot of ancestor changes in txFrame - it is an
   # expensive operation, specially when creating a new branch (ie when blk
   # is being applied to a block that is currently not a head)
-  txFrame.checkpoint(blk.header.number)
+  txFrame.checkpoint(number)
 
   c.lastSnapshots[pos] = txFrame
 

execution_chain/core/chain/forked_chain/chain_serialize.nim

@@ -129,7 +129,7 @@ proc replayBlock(fc: ForkedChainRef;
   # Update the snapshot before processing the block so that any vertexes in snapshots
   # from lower levels than the baseTxFrame are removed from the snapshot before running
   # the stateroot computation.
-  fc.updateSnapshot(parent.blk, parentFrame)
+  fc.updateSnapshot(parent.blk.header.number, parentFrame)
 
   # Set finalized to true in order to skip the stateroot check when replaying the
   # block because the blocks should have already been checked previously during