move: source service eagerly hydrates modules in memory (MystenLabs#1…

…2840)

## Description 

Eagerly reads and hydrates source code on server start. Doing this
eagerly is reasonable right now since source is small (we might opt for
gzip later too):

```
244K    sui-framework/packages/deepbook/sources
 72K    sui-framework/packages/move-stdlib/sources
348K    sui-framework/packages/sui-framework/sources
240K    sui-framework/packages/sui-system/sources
```

The type is set up with `Option` to allow hydrating source on first
request too, but I didn't want to go that route because then we need to
implemented a writer lock and seems pretty overkill given scope right
now.


---

For fun I looked at the local latency difference before/after this PR.
This isn't really meaningful on a local setup, but I've got the tooling
set up with `vegeta` for testing eventual deployment so figured to look
anyway.

100 requests per second over 15 seconds (latencies generally lower with
this PR).

Before

```
Requests      [total, rate, throughput]  1500, 100.07, 100.06
Duration      [total, attack, wait]      14.991483416s, 14.989767291s, 1.716125ms
Latencies     [mean, 50, 95, 99, max]    1.544413ms, 1.475097ms, 2.169692ms, 3.43996ms, 8.906125ms
Bytes In      [total, mean]              5073000, 3382.00
```

After

```
Requests      [total, rate, throughput]  1500, 100.07, 100.06
Duration      [total, attack, wait]      14.991182792s, 14.990031292s, 1.1515ms
Latencies     [mean, 50, 95, 99, max]    1.316599ms, 1.270261ms, 1.769853ms, 2.501024ms, 5.567708ms
Bytes In      [total, mean]              5073000, 3382.00
```

## Test Plan 

Updated test to use hydrated value.

crates/sui-source-validation-service/src/lib.rs

@@ -40,8 +40,15 @@ pub struct Packages {
     pub paths: Vec<String>,
 }
 
-/// Map (package address, module name) tuples to verified source paths.
-type SourceLookup = BTreeMap<(AccountAddress, Symbol), PathBuf>;
+#[derive(Debug)]
+pub struct SourceInfo {
+    pub path: PathBuf,
+    // Is Some when content is hydrated from disk.
+    pub source: Option<String>,
+}
+
+/// Map (package address, module name) tuples to verified source info.
+type SourceLookup = BTreeMap<(AccountAddress, Symbol), SourceInfo>;
 
 pub async fn verify_package(
     client: &SuiClient,
@@ -73,10 +80,14 @@ pub async fn verify_package(
     for v in &compiled_package.package.root_compiled_units {
         match v.unit {
             CompiledUnitEnum::Module(ref m) => {
-                map.insert((address, m.name), v.source_path.to_path_buf())
+                let path = v.source_path.to_path_buf();
+                let source = Some(fs::read_to_string(path.as_path())?);
+                map.insert((address, m.name), SourceInfo { path, source })
             }
             CompiledUnitEnum::Script(ref m) => {
-                map.insert((address, m.name), v.source_path.to_path_buf())
+                let path = v.source_path.to_path_buf();
+                let source = Some(fs::read_to_string(path.as_path())?);
+                map.insert((address, m.name), SourceInfo { path, source })
             }
         };
     }
@@ -264,16 +275,15 @@ async fn api_route(
 	let error = format!("Invalid hex address {address}");
 	return (StatusCode::BAD_REQUEST, Json(ErrorResponse { error }).into_response())
     };
-    let Some(path) = app_state.sources.get(&(address, symbol)) else {
+    let Some(SourceInfo {source : Some(source), ..}) = app_state.sources.get(&(address, symbol)) else {
 	let error = format!("No source found for {symbol} at address {address}" );
-	return (StatusCode::BAD_REQUEST, Json(ErrorResponse { error }).into_response())
-    };
-    let Ok(source) = fs::read_to_string(path) else {
-	let error = "Error reading source from disk".to_string();
-	return (StatusCode::INTERNAL_SERVER_ERROR, Json(ErrorResponse { error }).into_response())
+	return (StatusCode::NOT_FOUND, Json(ErrorResponse { error }).into_response())
     };
     (
         StatusCode::OK,
-        Json(SourceResponse { source }).into_response(),
+        Json(SourceResponse {
+            source: source.to_owned(),
+        })
+        .into_response(),
     )
 }

crates/sui-source-validation-service/tests/tests.rs

@@ -8,7 +8,8 @@ use std::{collections::BTreeMap, path::PathBuf};
 use move_core_types::account_address::AccountAddress;
 use move_symbol_pool::Symbol;
 use sui_source_validation_service::{
-    initialize, serve, verify_packages, AppState, CloneCommand, Config, Packages, SourceResponse,
+    initialize, serve, verify_packages, AppState, CloneCommand, Config, Packages, SourceInfo,
+    SourceResponse,
 };
 use test_cluster::TestClusterBuilder;
 
@@ -80,7 +81,10 @@ async fn test_api_route() -> anyhow::Result<()> {
             AccountAddress::from_hex_literal(address).unwrap(),
             Symbol::from(module),
         ),
-        source_path,
+        SourceInfo {
+            path: source_path,
+            source: Some("module address {...}".to_owned()),
+        },
     );
     tokio::spawn(serve(AppState { sources }).expect("Cannot start service."));
 
@@ -96,15 +100,7 @@ async fn test_api_route() -> anyhow::Result<()> {
         .json::<SourceResponse>()
         .await?;
 
-    let expected = expect![
-        r#"
-// Copyright (c) Mysten Labs, Inc.
-// SPDX-License-Identifier: Apache-2.0
-
-/// Dummy module for testing
-module std::address {}
-"#
-    ];
+    let expected = expect!["module address {...}"];
     expected.assert_eq(&json.source);
     Ok(())
 }