fuzz: Speed up utxo_snapshot by lazy re-init

The re-init is expensive, so skip it if there is no need.

Also, add an even faster fuzz target utxo_snapshot_invalid, which does
not need any re-init at all.

2 files changed, 24 insertions, 17 deletions

diff --git a/src/test/util/setup_common.cpp b/src/test/util/setup_common.cpp
index 2d6bc3c988..cf47d16faf 100644
--- a/src/test/util/setup_common.cpp
+++ b/src/test/util/setup_common.cpp
@@ -244,24 +244,30 @@ ChainTestingSetup::ChainTestingSetup(const ChainType chainType, TestOpts opts)
 
     m_node.notifications = std::make_unique<KernelNotifications>(*Assert(m_node.shutdown), m_node.exit_status, *Assert(m_node.warnings));
 
-    const ChainstateManager::Options chainman_opts{
-        .chainparams = chainparams,
-        .datadir = m_args.GetDataDirNet(),
-        .check_block_index = 1,
-        .notifications = *m_node.notifications,
-        .signals = m_node.validation_signals.get(),
-        .worker_threads_num = 2,
+    m_make_chainman = [this, &chainparams] {
+        Assert(!m_node.chainman);
+        const ChainstateManager::Options chainman_opts{
+            .chainparams = chainparams,
+            .datadir = m_args.GetDataDirNet(),
+            .check_block_index = 1,
+            .notifications = *m_node.notifications,
+            .signals = m_node.validation_signals.get(),
+            .worker_threads_num = 2,
+        };
+        const BlockManager::Options blockman_opts{
+            .chainparams = chainman_opts.chainparams,
+            .blocks_dir = m_args.GetBlocksDirPath(),
+            .notifications = chainman_opts.notifications,
+        };
+        m_node.chainman = std::make_unique<ChainstateManager>(*Assert(m_node.shutdown), chainman_opts, blockman_opts);
+        LOCK(m_node.chainman->GetMutex());
+        m_node.chainman->m_blockman.m_block_tree_db = std::make_unique<BlockTreeDB>(DBParams{
+            .path = m_args.GetDataDirNet() / "blocks" / "index",
+            .cache_bytes = static_cast<size_t>(m_cache_sizes.block_tree_db),
+            .memory_only = true,
+        });
     };
-    const BlockManager::Options blockman_opts{
-        .chainparams = chainman_opts.chainparams,
-        .blocks_dir = m_args.GetBlocksDirPath(),
-        .notifications = chainman_opts.notifications,
-    };
-    m_node.chainman = std::make_unique<ChainstateManager>(*Assert(m_node.shutdown), chainman_opts, blockman_opts);
-    m_node.chainman->m_blockman.m_block_tree_db = std::make_unique<BlockTreeDB>(DBParams{
-        .path = m_args.GetDataDirNet() / "blocks" / "index",
-        .cache_bytes = static_cast<size_t>(m_cache_sizes.block_tree_db),
-        .memory_only = true});
+    m_make_chainman();
 }
 
 ChainTestingSetup::~ChainTestingSetup()
diff --git a/src/test/util/setup_common.h b/src/test/util/setup_common.h
index 9515f0255e..7d69551516 100644
--- a/src/test/util/setup_common.h
+++ b/src/test/util/setup_common.h
@@ -81,6 +81,7 @@ struct ChainTestingSetup : public BasicTestingSetup {
     node::CacheSizes m_cache_sizes{};
     bool m_coins_db_in_memory{true};
     bool m_block_tree_db_in_memory{true};
+    std::function<void()> m_make_chainman{};
 
     explicit ChainTestingSetup(const ChainType chainType = ChainType::MAIN, TestOpts = {});
     ~ChainTestingSetup();