feat: allow export spine-only snapshots with forest-cli snapshot export -d 0

src/chain_sync/chain_muxer.rs

@@ -3,7 +3,7 @@
 
 use serde::{Deserialize, Serialize};
 
-const DEFAULT_RECENT_STATE_ROOTS: i64 = 2000;
+pub const DEFAULT_RECENT_STATE_ROOTS: i64 = 2000;
 
 /// Structure that defines syncing configuration options
 #[derive(Debug, Deserialize, Serialize, Clone, PartialEq, Eq)]

src/chain_sync/mod.rs

@@ -3,7 +3,7 @@
 
 mod bad_block_cache;
 mod chain_follower;
-mod chain_muxer;
+pub mod chain_muxer;
 pub mod consensus;
 pub mod metrics;
 pub mod network_context;

src/cli/subcommands/snapshot_cmd.rs

@@ -2,12 +2,13 @@
 // SPDX-License-Identifier: Apache-2.0, MIT
 
 use crate::chain::FilecoinSnapshotVersion;
-use crate::chain_sync::SyncConfig;
+use crate::chain_sync::chain_muxer::DEFAULT_RECENT_STATE_ROOTS;
 use crate::cli_shared::snapshot::{self, TrustedVendor};
 use crate::db::car::forest::new_forest_car_temp_path_in;
 use crate::networks::calibnet;
 use crate::rpc::chain::ForestChainExportDiffParams;
-use crate::rpc::{self, chain::ForestChainExportParams, prelude::*, types::ApiTipsetKey};
+use crate::rpc::{self, chain::ForestChainExportParams, prelude::*};
+use crate::shim::policy::policy_constants::CHAIN_FINALITY;
 use anyhow::Context as _;
 use chrono::DateTime;
 use clap::Subcommand;
@@ -34,10 +35,10 @@ pub enum SnapshotCommands {
         /// Tipset to start the export from, default is the chain head
         #[arg(short, long)]
         tipset: Option<i64>,
-        /// How many state-roots to include. Lower limit is 900 for `calibnet` and `mainnet`.
-        #[arg(short, long)]
-        depth: Option<crate::chain::ChainEpochDelta>,
-        /// Export snapshot in the experimental v2 format(FRC-0108).
+        /// How many state trees to include. 0 for chain spine with no state trees.
+        #[arg(short, long, default_value_t = DEFAULT_RECENT_STATE_ROOTS)]
+        depth: crate::chain::ChainEpochDelta,
+        /// Snapshot format to export.
         #[arg(long, value_enum, default_value_t = FilecoinSnapshotVersion::V1)]
         format: FilecoinSnapshotVersion,
     },
@@ -69,12 +70,18 @@ impl SnapshotCommands {
                 depth,
                 format,
             } => {
-                let chain_head = ChainHead::call(&client, ()).await?;
+                anyhow::ensure!(
+                    depth >= 0,
+                    "--depth must be non-negative; use 0 for spine-only snapshots"
+                );
 
-                let epoch = tipset.unwrap_or(chain_head.epoch());
+                if depth < CHAIN_FINALITY {
+                    tracing::warn!(
+                        "Depth {depth} should be no less than CHAIN_FINALITY {CHAIN_FINALITY} to export a valid lite snapshot"
+                    );
+                }
 
                 let raw_network_name = StateNetworkName::call(&client, ()).await?;
-
                 // For historical reasons and backwards compatibility if snapshot services or their
                 // consumers relied on the `calibnet`, we use `calibnet` as the chain name.
                 let chain_name = if raw_network_name == calibnet::NETWORK_GENESIS_NAME {
@@ -83,8 +90,17 @@ impl SnapshotCommands {
                     raw_network_name.as_str()
                 };
 
-                let tipset =
-                    ChainGetTipSetByHeight::call(&client, (epoch, Default::default())).await?;
+                let tipset = if let Some(epoch) = tipset {
+                    // This could take a while when the requested epoch is far behind the chain head
+                    client
+                        .call(
+                            ChainGetTipSetByHeight::request((epoch, Default::default()))?
+                                .with_timeout(Duration::from_secs(60 * 15)),
+                        )
+                        .await?
+                } else {
+                    ChainHead::call(&client, ()).await?
+                };
 
                 let output_path = match output_path.is_dir() {
                     true => output_path.join(snapshot::filename(
@@ -94,7 +110,7 @@ impl SnapshotCommands {
                             .unwrap_or_default()
                             .naive_utc()
                             .date(),
-                        epoch,
+                        tipset.epoch(),
                         true,
                     )),
                     false => output_path.clone(),
@@ -105,10 +121,10 @@ impl SnapshotCommands {
 
                 let params = ForestChainExportParams {
                     version: format,
-                    epoch,
-                    recent_roots: depth.unwrap_or(SyncConfig::default().recent_state_roots),
+                    epoch: tipset.epoch(),
+                    recent_roots: depth,
                     output_path: temp_path.to_path_buf(),
-                    tipset_keys: ApiTipsetKey(Some(chain_head.key().clone())),
+                    tipset_keys: tipset.key().clone().into(),
                     skip_checksum,
                     dry_run,
                 };

src/rpc/methods/chain.rs

@@ -332,14 +332,6 @@ impl RpcMethod<1> for ForestChainExport {
             return Err(anyhow::anyhow!("Another chain export job is still in progress").into());
         }
 
-        let chain_finality = ctx.chain_config().policy.chain_finality;
-        if recent_roots < chain_finality {
-            return Err(anyhow::anyhow!(format!(
-                "recent-stateroots must be greater than {chain_finality}"
-            ))
-            .into());
-        }
-
         let head = ctx.chain_store().load_required_tipset_or_heaviest(&tsk)?;
         let start_ts =
             ctx.chain_index()