Merge bitcoin/bitcoin#28051: Get rid of shutdown.cpp/shutdown.h, use SignalInterrupt directly

6db04be102 Get rid of shutdown.cpp/shutdown.h, use SignalInterrupt directly (Ryan Ofsky)
213542b625 refactor: Add InitContext function to initialize NodeContext with global pointers (Ryan Ofsky)
feeb7b816a refactor: Remove calls to StartShutdown from KernelNotifications (Ryan Ofsky)
6824eecaf1 refactor: Remove call to StartShutdown from stop RPC (Ryan Ofsky)
1d92d89edb util: Get rid of uncaught exceptions thrown by SignalInterrupt class (Ryan Ofsky)
ba93966368 refactor: Remove call to ShutdownRequested from IndexWaitSynced (Ryan Ofsky)
42e5829d97 refactor: Remove call to ShutdownRequested from HTTPRequest (Ryan Ofsky)
73133c36aa refactor: Add NodeContext::shutdown member (Ryan Ofsky)
f4a8bd6e2f refactor: Remove call to StartShutdown from qt (Ryan Ofsky)
f0c73c1336 refactor: Remove call to ShutdownRequested from rpc/mining (Ryan Ofsky)
263b23f008 refactor: Remove call to ShutdownRequested from chainstate init (Ryan Ofsky)

Pull request description:

  This change drops `shutdown.h` and `shutdown.cpp` files, replacing them with a `NodeContext::shutdown` member which is used to trigger shutdowns directly. This gets rid of an unnecessary layer of indirection, and allows getting rid of the `kernel::g_context` global.

  Additionally, this PR tries to improve error handling of `SignalInterrupt` code by marking relevant methods `[[nodiscard]]` to avoid the possibility of uncaught exceptions mentioned https://github.com/bitcoin/bitcoin/pull/27861#discussion_r1255496707.

  Behavior is changing In a few cases which are noted in individual commit messages. Particularly: GUI code more consistently interrupts RPCs when it is shutting down, shutdown state no longer persists between unit tests, the stop RPC now returns an RPC error if requesting shutdown fails instead of aborting, and other failed shutdown calls now log errors instead of aborting.

  This PR is a net reduction in lines of code, but in some cases the explicit error handling and lack of global shutdown functions do make it more verbose. The verbosity can be seen as good thing if it discourages more code from directly triggering shutdowns, and instead encourages code to return errors or send notifications that could be translated into shutdowns. Probably a number of existing shutdown calls could just be replaced by better error handling.

ACKs for top commit:
  achow101:
    ACK 6db04be102
  TheCharlatan:
    Re-ACK 6db04be102
  maflcko:
    ACK 6db04be102 👗
  stickies-v:
    re-ACK 6db04be102

Tree-SHA512: 7a34cb69085f37e813c43bdaded1a0cbf6c53bd95fdde96f0cb45346127fc934604c43bccd3328231ca2f1faf712a7418d047ceabd22ef2dca3c32ebb659e634

src/test/util/index.cpp

@@ -5,16 +5,16 @@
 #include <test/util/index.h>
 
 #include <index/base.h>
-#include <shutdown.h>
 #include <util/check.h>
+#include <util/signalinterrupt.h>
 #include <util/time.h>
 
-void IndexWaitSynced(const BaseIndex& index)
+void IndexWaitSynced(const BaseIndex& index, const util::SignalInterrupt& interrupt)
 {
     while (!index.BlockUntilSyncedToCurrentChain()) {
         // Assert shutdown was not requested to abort the test, instead of looping forever, in case
         // there was an unexpected error in the index that caused it to stop syncing and request a shutdown.
-        Assert(!ShutdownRequested());
+        Assert(!interrupt);
 
         UninterruptibleSleep(100ms);
     }

src/test/util/index.h

@@ -6,8 +6,11 @@
 #define BITCOIN_TEST_UTIL_INDEX_H
 
 class BaseIndex;
+namespace util {
+class SignalInterrupt;
+} // namespace util
 
 /** Block until the index is synced to the current chain */
-void IndexWaitSynced(const BaseIndex& index);
+void IndexWaitSynced(const BaseIndex& index, const util::SignalInterrupt& interrupt);
 
 #endif // BITCOIN_TEST_UTIL_INDEX_H

src/test/util/setup_common.cpp

@@ -40,7 +40,6 @@
 #include <rpc/server.h>
 #include <scheduler.h>
 #include <script/sigcache.h>
-#include <shutdown.h>
 #include <streams.h>
 #include <test/util/net.h>
 #include <test/util/random.h>
@@ -102,6 +101,7 @@ BasicTestingSetup::BasicTestingSetup(const ChainType chainType, const std::vecto
     : m_path_root{fs::temp_directory_path() / "test_common_" PACKAGE_NAME / g_insecure_rand_ctx_temp_path.rand256().ToString()},
       m_args{}
 {
+    m_node.shutdown = &m_interrupt;
     m_node.args = &gArgs;
     std::vector<const char*> arguments = Cat(
         {
@@ -179,7 +179,7 @@ ChainTestingSetup::ChainTestingSetup(const ChainType chainType, const std::vecto
 
     m_cache_sizes = CalculateCacheSizes(m_args);
 
-    m_node.notifications = std::make_unique<KernelNotifications>(m_node.exit_status);
+    m_node.notifications = std::make_unique<KernelNotifications>(*Assert(m_node.shutdown), m_node.exit_status);
 
     const ChainstateManager::Options chainman_opts{
         .chainparams = chainparams,
@@ -194,7 +194,7 @@ ChainTestingSetup::ChainTestingSetup(const ChainType chainType, const std::vecto
         .blocks_dir = m_args.GetBlocksDirPath(),
         .notifications = chainman_opts.notifications,
     };
-    m_node.chainman = std::make_unique<ChainstateManager>(m_node.kernel->interrupt, chainman_opts, blockman_opts);
+    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),

src/test/util/setup_common.h

@@ -47,6 +47,7 @@ static constexpr CAmount CENT{1000000};
  * This just configures logging, data dir and chain parameters.
  */
 struct BasicTestingSetup {
+    util::SignalInterrupt m_interrupt;
     node::NodeContext m_node; // keep as first member to be destructed last
 
     explicit BasicTestingSetup(const ChainType chainType = ChainType::MAIN, const std::vector<const char*>& extra_args = {});