SnapshotPackagerService pushes incremental snapshot hashes to CRDS (#20442)

Now that CRDS supports incremental snapshot hashes,
SnapshotPackagerService needs to push 'em!

This commit does two main things:

1. SnapshotPackagerService now knows about incremental snapshot hashes,
   and will push SnapshotPackage::IncrementalSnapshot hashes to CRDS.
2. At startup, when loading from a full + incremental snapshot, the
   hashes need to be passed all the way to SnapshotPackagerService so it
   can push these starting hashes to CRDS.  Those values have been piped
   through.

Fixes #20441 and #20423

runtime/src/lib.rs

@@ -42,6 +42,7 @@ pub mod serde_snapshot;
 mod shared_buffer_reader;
 pub mod snapshot_archive_info;
 pub mod snapshot_config;
+pub mod snapshot_hash;
 pub mod snapshot_package;
 pub mod snapshot_utils;
 pub mod sorted_storages;

runtime/src/snapshot_hash.rs

@@ -0,0 +1,44 @@
+//! Helper types and functions for handling and dealing with snapshot hashes.
+use solana_sdk::{clock::Slot, hash::Hash};
+
+/// At startup, when loading from snapshots, the starting snapshot hashes need to be passed to
+/// SnapshotPackagerService, which is in charge of pushing the hashes to CRDS.  This struct wraps
+/// up those values make it easier to pass from bank_forks_utils, through validator, to
+/// SnapshotPackagerService.
+#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
+pub struct StartingSnapshotHashes {
+    pub full: FullSnapshotHash,
+    pub incremental: Option<IncrementalSnapshotHash>,
+}
+
+/// Used by SnapshotPackagerService and SnapshotGossipManager, this struct adds type safety to
+/// ensure a full snapshot hash is pushed to the right CRDS.
+#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
+pub struct FullSnapshotHash {
+    pub hash: (Slot, Hash),
+}
+
+/// Used by SnapshotPackagerService and SnapshotGossipManager, this struct adds type safety to
+/// ensure an incremental snapshot hash is pushed to the right CRDS.  `base` is the (full) snapshot
+/// this incremental snapshot (`hash`) is based on.
+#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
+pub struct IncrementalSnapshotHash {
+    pub base: (Slot, Hash),
+    pub hash: (Slot, Hash),
+}
+
+/// FullSnapshotHashes is used by SnapshotPackagerService to collect the snapshot hashes from full
+/// snapshots and then push those hashes to CRDS.
+#[derive(Debug, Default, Clone, PartialEq, Eq)]
+pub struct FullSnapshotHashes {
+    pub hashes: Vec<(Slot, Hash)>,
+}
+
+/// IncrementalSnapshotHashes is used by SnapshotPackagerService to collect the snapshot hashes
+/// from incremental snapshots and then push those hashes to CRDS.  `base` is the (full) snapshot
+/// all the incremental snapshots (`hashes`) are based on.
+#[derive(Debug, Default, Clone, PartialEq, Eq)]
+pub struct IncrementalSnapshotHashes {
+    pub base: (Slot, Hash),
+    pub hashes: Vec<(Slot, Hash)>,
+}