perf(gossip): reduce gossip table memory usage

src/gossip/data.zig

@@ -176,7 +176,7 @@ pub const GossipKey = union(GossipDataTag) {
     RestartHeaviestFork: Pubkey,
 };
 
-const GossipDataTag = enum(u32) {
+pub const GossipDataTag = enum(u32) {
     LegacyContactInfo,
     Vote,
     LowestSlot,
@@ -191,6 +191,25 @@ const GossipDataTag = enum(u32) {
     ContactInfo,
     RestartLastVotedForkSlots,
     RestartHeaviestFork,
+
+    pub fn Value(self: GossipDataTag) type {
+        return switch (self) {
+            .LegacyContactInfo => LegacyContactInfo,
+            .Vote => struct { u8, Vote },
+            .LowestSlot => struct { u8, LowestSlot },
+            .LegacySnapshotHashes => LegacySnapshotHashes,
+            .AccountsHashes => AccountsHashes,
+            .EpochSlots => struct { u8, EpochSlots },
+            .LegacyVersion => LegacyVersion,
+            .Version => Version,
+            .NodeInstance => NodeInstance,
+            .DuplicateShred => struct { u16, DuplicateShred },
+            .SnapshotHashes => SnapshotHashes,
+            .ContactInfo => ContactInfo,
+            .RestartLastVotedForkSlots => RestartLastVotedForkSlots,
+            .RestartHeaviestFork => RestartHeaviestFork,
+        };
+    }
 };
 
 /// Analogous to [CrdsData](https://github.com/solana-labs/solana/blob/e0203f22dc83cb792fa97f91dbe6e924cbd08af1/gossip/src/crds_value.rs#L85)

src/gossip/dump_service.zig

@@ -54,7 +54,9 @@ pub const GossipDumpService = struct {
 
             // write records to string
             const endec = base58.Table.BITCOIN;
-            for (gossip_table.store.values()) |gossip_versioned_data| {
+            var iterator = gossip_table.store.iterator();
+            while (iterator.next()) |entry| {
+                const gossip_versioned_data = entry.getVersionedData();
                 const val: SignedGossipData = gossip_versioned_data.value;
 
                 var encoded_buf: [50]u8 = undefined;

src/gossip/lib.zig

@@ -1,6 +1,7 @@
 pub const active_set = @import("active_set.zig");
 pub const data = @import("data.zig");
 pub const dump_service = @import("dump_service.zig");
+pub const map = @import("map.zig");
 pub const message = @import("message.zig");
 pub const ping_pong = @import("ping_pong.zig");
 pub const pull_request = @import("pull_request.zig");