fix: retrieve inscriptions from cache

.github/workflows/build.yaml

@@ -0,0 +1,28 @@
+name: Build
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Install Rust Toolchain Components
+        uses: actions-rs/toolchain@v1
+        with:
+          components: clippy, rustfmt
+          override: true
+          toolchain: stable
+
+      - uses: Swatinem/rust-cache@v2
+
+      - name: Format
+        run: cargo fmt --all -- --check

src/block.rs

@@ -221,12 +221,17 @@ impl<'block> InscriptionUpdater<'block> {
             }
 
             let previous_output = format!("{}:{}", tx_in.outpoint.txid, tx_in.outpoint.index);
-            let inscriptions_str_at_output = self
-                .output_inscription
-                .get(previous_output.as_bytes())
-                .unwrap_or_default();
-
-            let inscriptions_str = String::from_utf8(inscriptions_str_at_output)?;
+            let inscriptions_str = self
+                .output_inscription_cache
+                .entry(previous_output.clone())
+                .or_insert_with(|| {
+                    String::from_utf8(
+                        self.output_inscription
+                            .get(previous_output.as_bytes())
+                            .unwrap_or_default(),
+                    )
+                    .unwrap()
+                });
             if inscriptions_str != "" {
                 for (inscription_id, inscription_offset) in
                     inscriptions_str