Name currently-unnamed threads that we can rename

After this, the only threads that aren't named are the LevelDB
background threads.

Cargo.lock

@@ -982,6 +982,7 @@ dependencies = [
  "orchard",
  "rand 0.8.5",
  "rand_core 0.6.3",
+ "rayon",
  "secp256k1",
  "secrecy",
  "subtle",

Cargo.toml

@@ -57,6 +57,9 @@ zcash_proofs = "0.6"
 ed25519-zebra = "3"
 zeroize = "1.4.2"
 
+# Rust threading
+rayon = "1.5"
+
 # Metrics
 ipnet = "2"
 metrics = "0.17"

src/asyncrpcqueue.cpp

@@ -3,6 +3,7 @@
 // file COPYING or https://www.opensource.org/licenses/mit-license.php .
 
 #include "asyncrpcqueue.h"
+#include "util.h"
 
 static std::atomic<size_t> workerCounter(0);
 
@@ -26,6 +27,8 @@ AsyncRPCQueue::~AsyncRPCQueue() {
  * A worker will execute this method on a new thread
  */
 void AsyncRPCQueue::run(size_t workerId) {
+    std::string s = strprintf("zc-asyncrpc-%s", workerId);
+    RenameThread(s.c_str());
 
     while (true) {
         AsyncRPCOperationId key;

src/bitcoind.cpp

@@ -43,6 +43,10 @@ static bool fDaemon;
 
 void WaitForShutdown(boost::thread_group* threadGroup)
 {
+    // This is the main process thread, but after this point, all we do here is wait for
+    // shutdown, and then shut down the node.
+    RenameThread("zc-wait-to-stop");
+
     bool fShutdown = ShutdownRequested();
     // Tell the main threads to shutdown.
     while (!fShutdown)

src/init.cpp

@@ -66,6 +66,7 @@
 #include "zmq/zmqnotificationinterface.h"
 #endif
 
+#include <rust/init.h>
 #include <rust/metrics.h>
 
 #include "librustzcash.h"
@@ -1071,6 +1072,9 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
 
     std::set_new_handler(new_handler_terminate);
 
+    // Set up global Rayon threadpool.
+    zcashd_init_rayon_threadpool();
+
     // ********************************************************* Step 2: parameter interactions
     const CChainParams& chainparams = Params();
 

src/rust/include/rust/init.h

@@ -0,0 +1,19 @@
+// Copyright (c) 2022 The Zcash developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or https://www.opensource.org/licenses/mit-license.php .
+
+#ifndef ZCASH_RUST_INCLUDE_RUST_INIT_H
+#define ZCASH_RUST_INCLUDE_RUST_INIT_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/// Initializes the global Rayon threadpool.
+void zcashd_init_rayon_threadpool();
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // ZCASH_RUST_INCLUDE_RUST_INIT_H

src/rust/src/init_ffi.rs

@@ -0,0 +1,7 @@
+#[no_mangle]
+pub extern "C" fn zcashd_init_rayon_threadpool() {
+    rayon::ThreadPoolBuilder::new()
+        .thread_name(|i| format!("zc-rayon-{}", i))
+        .build_global()
+        .expect("Only initialized once");
+}

src/rust/src/rustzcash.rs

@@ -77,6 +77,7 @@ mod builder_ffi;
 mod history_ffi;
 mod incremental_merkle_tree;
 mod incremental_merkle_tree_ffi;
+mod init_ffi;
 mod orchard_ffi;
 mod orchard_keys_ffi;
 mod transaction_ffi;