bees: handle SIGTERM and SIGINT, force immediate flush and exit

Capture SIGINT and SIGTERM and shut down, preserving current completed
crawl and hash table state.

  * Executing tasks are completed, queued tasks are paused.
  * Crawl state is saved.
  * The crawl master and crawl writeback threads are terminated.
  * The task queue is flushed.
  * Dirty hash table extents are flushed.
  * Hash prefetch and writeback threads are terminated.
  * Hash table is deallocated.
  * FD caches and tmpfiles are destroyed.
  * Assuming the above didn't crash or deadlock, bees exits.

The above order isn't the fastest, but it does roughly follow the
shared_ptr dependencies and avoids data races--especially those that
might lead to bees reporting an extent scanned when it was only queued
for future scanning that did not occur.

In case of a violation of expected shared_ptr dependency order,
exceptions in BeesContext child object accessor methods (i.e. roots(),
hash_table(), etc) prevent any further progress in threads that somehow
remain unexpectedly active.

Move some threads from main into BeesContext so they can be stopped
via BeesContext.  The main thread now runs a loop waiting for signals.

A slow FD leak was discovered in TempFile handling.  This has not been
fixed yet, but an implementation detail of the C++ runtime library makes
the leak so slow it may never be important enough to fix.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>

src/bees-context.cc

@@ -1,5 +1,6 @@
 #include "bees.h"
 
+#include "crucible/cleanup.h"
 #include "crucible/limits.h"
 #include "crucible/string.h"
 #include "crucible/task.h"
@@ -13,9 +14,13 @@
 // struct rusage
 #include <sys/resource.h>
 
+// struct sigset
+#include <signal.h>
+
 using namespace crucible;
 using namespace std;
 
+
 static inline
 const char *
 getenv_or_die(const char *name)
@@ -82,17 +87,15 @@ BeesContext::dump_status()
 	if (!status_charp) return;
 	string status_file(status_charp);
 	BEESLOGINFO("Writing status to file '" << status_file << "' every " << BEES_STATUS_INTERVAL << " sec");
-	while (1) {
-		BEESNOTE("waiting " << BEES_STATUS_INTERVAL);
-		sleep(BEES_STATUS_INTERVAL);
-
+	Timer total_timer;
+	while (!m_stop_status) {
 		BEESNOTE("writing status to file '" << status_file << "'");
 		ofstream ofs(status_file + ".tmp");
 
 		auto thisStats = BeesStats::s_global;
 		ofs << "TOTAL:\n";
 		ofs << "\t" << thisStats << "\n";
-		auto avg_rates = thisStats / m_total_timer.age();
+		auto avg_rates = thisStats / total_timer.age();
 		ofs << "RATES:\n";
 		ofs << "\t" << avg_rates << "\n";
 
@@ -113,42 +116,65 @@ BeesContext::dump_status()
 
 		BEESNOTE("renaming status file '" << status_file << "'");
 		rename((status_file + ".tmp").c_str(), status_file.c_str());
+
+		BEESNOTE("idle " << BEES_STATUS_INTERVAL);
+		unique_lock<mutex> lock(m_stop_mutex);
+		if (m_stop_status) {
+			return;
+		}
+		m_stop_condvar.wait_for(lock, chrono::duration<double>(BEES_STATUS_INTERVAL));
 	}
 }
 
 void
 BeesContext::show_progress()
 {
-	auto lastProgressStats = BeesStats::s_global;
-	auto lastStats = lastProgressStats;
+	auto lastStats = BeesStats::s_global;
 	Timer stats_timer;
-	while (1) {
-		sleep(BEES_PROGRESS_INTERVAL);
+	Timer all_timer;
+	while (!stop_requested()) {
+		BEESNOTE("idle " << BEES_PROGRESS_INTERVAL);
 
-		if (stats_timer.age() > BEES_STATS_INTERVAL) {
-			stats_timer.lap();
-
-			auto thisStats = BeesStats::s_global;
-			auto avg_rates = lastStats / BEES_STATS_INTERVAL;
-			BEESLOGINFO("TOTAL: " << thisStats);
-			BEESLOGINFO("RATES: " << avg_rates);
-			lastStats = thisStats;
+		unique_lock<mutex> lock(m_stop_mutex);
+		if (m_stop_requested) {
+			return;
 		}
+		m_stop_condvar.wait_for(lock, chrono::duration<double>(BEES_PROGRESS_INTERVAL));
 
-		BEESLOGINFO("ACTIVITY:");
-
+		// Snapshot stats and timer state
 		auto thisStats = BeesStats::s_global;
-		auto deltaStats = thisStats - lastProgressStats;
-		if (deltaStats) {
-			BEESLOGINFO("\t" << deltaStats / BEES_PROGRESS_INTERVAL);
-		};
-		lastProgressStats = thisStats;
+		auto stats_age = stats_timer.age();
+		auto all_age = all_timer.age();
+		stats_timer.lap();
 
+		auto avg_rates = thisStats / stats_age;
+
+		BEESNOTE("logging event counter totals for last " << all_timer);
+		BEESLOGINFO("TOTAL COUNTS (" << all_age << "s):\n\t" << thisStats);
+
+		BEESNOTE("logging event counter rates for last " << all_timer);
+		BEESLOGINFO("TOTAL RATES (" << all_age << "s):\n\t" << avg_rates);
+
+		BEESNOTE("logging event counter delta counts for last " << stats_age);
+		BEESLOGINFO("DELTA COUNTS (" << stats_age << "s):");
+
+		auto deltaStats = thisStats - lastStats;
+		BEESLOGINFO("\t" << deltaStats / stats_age);
+
+		BEESNOTE("logging event counter delta rates for last " << stats_age);
+		BEESLOGINFO("DELTA RATES (" << stats_age << "s):");
+
+		auto deltaRates = deltaStats / stats_age;
+		BEESLOGINFO("\t" << deltaRates);
+
+		BEESNOTE("logging current thread status");
 		BEESLOGINFO("THREADS:");
 
 		for (auto t : BeesNote::get_status()) {
 			BEESLOGINFO("\ttid " << t.first << ": " << t.second);
 		}
+
+		lastStats = thisStats;
 	}
 }
 
@@ -171,11 +197,19 @@ BeesContext::home_fd()
 }
 
 BeesContext::BeesContext(shared_ptr<BeesContext> parent) :
-	m_parent_ctx(parent)
+	m_parent_ctx(parent),
+	m_progress_thread("progress_report"),
+	m_status_thread("status_report")
 {
 	if (m_parent_ctx) {
 		m_fd_cache = m_parent_ctx->fd_cache();
 	}
+	m_progress_thread.exec([=]() {
+		show_progress();
+	});
+	m_status_thread.exec([=]() {
+		dump_status();
+	});
 }
 
 bool
@@ -745,7 +779,7 @@ BeesContext::scan_forward(const BeesFileRange &bfr)
 
 	Extent e;
 	catch_all([&]() {
-		while (true) {
+		while (!stop_requested()) {
 			e = ew.current();
 
 			catch_all([&]() {
@@ -881,11 +915,106 @@ BeesContext::set_root_fd(Fd fd)
 	m_resolve_cache.func([&](BeesAddress addr) -> BeesResolveAddrResult {
 		return resolve_addr_uncached(addr);
 	});
+}
 
-	// Start queue producers
+const char *
+BeesHalt::what() const noexcept
+{
+	return "bees stop requested";
+}
+
+void
+BeesContext::start()
+{
+	BEESLOGNOTICE("Starting bees main loop...");
+	BEESNOTE("starting BeesContext");
+
+	// Force these to exist now so we don't have recursive locking
+	// operations trying to access them
+	fd_cache();
+	hash_table();
+
+	// Kick off the crawlers
 	roots();
+}
 
-	BEESLOGINFO("returning from set_root_fd in " << name_fd(fd));
+void
+BeesContext::stop()
+{
+	Timer stop_timer;
+	BEESLOGNOTICE("Stopping bees...");
+	BEESLOGWARN("WARNING: This feature is EXPERIMENTAL and may not work!");
+
+	BEESNOTE("setting stop_request flag");
+
+	BEESNOTE("pausing work queue");
+	BEESLOGDEBUG("Pausing work queue");
+	TaskMaster::set_thread_count(0);
+
+	BEESLOGDEBUG("Setting stop_request flag");
+	unique_lock<mutex> lock(m_stop_mutex);
+	m_stop_requested = true;
+	m_stop_condvar.notify_all();
+	lock.unlock();
+
+	// Stop crawlers first so we get good progress persisted on disk
+	BEESNOTE("stopping crawlers");
+	BEESLOGDEBUG("Stopping crawlers");
+	if (m_roots) {
+		m_roots->stop();
+		m_roots.reset();
+	} else {
+		BEESLOGDEBUG("Crawlers not running");
+	}
+
+	BEESNOTE("cancelling work queue");
+	BEESLOGDEBUG("Cancelling work queue");
+	TaskMaster::cancel();
+
+	BEESNOTE("stopping hash table");
+	BEESLOGDEBUG("Stopping hash table");
+	if (m_hash_table) {
+		m_hash_table->stop();
+		m_hash_table.reset();
+	} else {
+		BEESLOGDEBUG("Hash table not running");
+	}
+
+	BEESNOTE("closing tmpfiles");
+	BEESLOGDEBUG("Closing tmpfiles");
+	m_tmpfiles.clear();
+
+	BEESNOTE("closing FD caches");
+	BEESLOGDEBUG("Closing FD caches");
+	if (m_fd_cache) {
+		m_fd_cache->clear();
+		BEESNOTE("destroying FD caches");
+		BEESLOGDEBUG("Destroying FD caches");
+		m_fd_cache.reset();
+	}
+
+	BEESNOTE("waiting for progress thread");
+	BEESLOGDEBUG("Waiting for progress thread");
+	m_progress_thread.join();
+
+	// XXX: nobody can see this BEESNOTE because we are killing the
+	// thread that publishes it
+	BEESNOTE("waiting for progress thread");
+	BEESLOGDEBUG("Waiting for progress thread");
+	lock.lock();
+	m_stop_status = true;
+	m_stop_condvar.notify_all();
+	lock.unlock();
+	m_status_thread.join();
+
+	BEESLOGNOTICE("bees stopped in " << stop_timer << " sec");
+}
+
+bool
+BeesContext::stop_requested() const
+{
+	unique_lock<mutex> lock(m_stop_mutex);
+	return m_stop_requested;
 }
 
 void
@@ -910,22 +1039,32 @@ BeesContext::is_blacklisted(const BeesFileId &fid) const
 shared_ptr<BeesTempFile>
 BeesContext::tmpfile()
 {
-	// There need be only one, this is not a high-contention path
-	static mutex s_mutex;
-	unique_lock<mutex> lock(s_mutex);
+	// FIXME: this whole thing leaks FDs (quite slowly).  Make a pool instead.
+
+	unique_lock<mutex> lock(m_stop_mutex);
+
+	if (m_stop_requested) {
+		throw BeesHalt();
+	}
 
 	if (!m_tmpfiles[this_thread::get_id()]) {
-		m_tmpfiles[this_thread::get_id()] = make_shared<BeesTempFile>(shared_from_this());
+		// We know we are the only possible accessor of this,
+		// so drop the lock to avoid a deadlock loop
+		lock.unlock();
+		auto rv = make_shared<BeesTempFile>(shared_from_this());
+		lock.lock();
+		m_tmpfiles[this_thread::get_id()] = rv;
 	}
-	auto rv = m_tmpfiles[this_thread::get_id()];
-	return rv;
+	return m_tmpfiles[this_thread::get_id()];
 }
 
 shared_ptr<BeesFdCache>
 BeesContext::fd_cache()
 {
-	static mutex s_mutex;
-	unique_lock<mutex> lock(s_mutex);
+	unique_lock<mutex> lock(m_stop_mutex);
+	if (m_stop_requested) {
+		throw BeesHalt();
+	}
 	if (!m_fd_cache) {
 		m_fd_cache = make_shared<BeesFdCache>();
 	}
@@ -936,8 +1075,10 @@ BeesContext::fd_cache()
 shared_ptr<BeesRoots>
 BeesContext::roots()
 {
-	static mutex s_mutex;
-	unique_lock<mutex> lock(s_mutex);
+	unique_lock<mutex> lock(m_stop_mutex);
+	if (m_stop_requested) {
+		throw BeesHalt();
+	}
 	if (!m_roots) {
 		m_roots = make_shared<BeesRoots>(shared_from_this());
 	}
@@ -948,8 +1089,10 @@ BeesContext::roots()
 shared_ptr<BeesHashTable>
 BeesContext::hash_table()
 {
-	static mutex s_mutex;
-	unique_lock<mutex> lock(s_mutex);
+	unique_lock<mutex> lock(m_stop_mutex);
+	if (m_stop_requested) {
+		throw BeesHalt();
+	}
 	if (!m_hash_table) {
 		m_hash_table = make_shared<BeesHashTable>(shared_from_this(), "beeshash.dat");
 	}

src/bees-hash.cc

@@ -130,13 +130,11 @@ BeesHashTable::flush_dirty_extent(uint64_t extent_index)
 		wrote_extent = true;
 	});
 
-	BEESNOTE("flush rate limited after extent #" << extent_index << " of " << m_extents << " extents");
-	m_flush_rate_limit.sleep_for(BLOCK_SIZE_HASHTAB_EXTENT);
 	return wrote_extent;
 }
 
-void
-BeesHashTable::flush_dirty_extents()
+size_t
+BeesHashTable::flush_dirty_extents(bool slowly)
 {
 	THROW_CHECK1(runtime_error, m_buckets, m_buckets > 0);
 
@@ -144,12 +142,22 @@ BeesHashTable::flush_dirty_extents()
 	for (size_t extent_index = 0; extent_index < m_extents; ++extent_index) {
 		if (flush_dirty_extent(extent_index)) {
 			++wrote_extents;
+			if (slowly) {
+				BEESNOTE("flush rate limited after extent #" << extent_index << " of " << m_extents << " extents");
+				chrono::duration<double> sleep_time(m_flush_rate_limit.sleep_time(BLOCK_SIZE_HASHTAB_EXTENT));
+				unique_lock<mutex> lock(m_stop_mutex);
+				if (m_stop_requested) {
+					BEESLOGDEBUG("Stop requested in hash table flush_dirty_extents");
+					break;
+				}
+				m_stop_condvar.wait_for(lock, sleep_time);
+			}
 		}
 	}
-
-	BEESNOTE("idle after writing " << wrote_extents << " of " << m_extents << " extents");
-	unique_lock<mutex> lock(m_dirty_mutex);
-	m_dirty_condvar.wait(lock);
+	if (!slowly) {
+		BEESLOGINFO("Flushed " << wrote_extents << " of " << m_extents << " extents");
+	}
+	return wrote_extents;
 }
 
 void
@@ -160,15 +168,29 @@ BeesHashTable::set_extent_dirty_locked(uint64_t extent_index)
 
 	// Signal writeback thread
 	unique_lock<mutex> dirty_lock(m_dirty_mutex);
+	m_dirty = true;
 	m_dirty_condvar.notify_one();
 }
 
 void
 BeesHashTable::writeback_loop()
 {
-	while (true) {
-		flush_dirty_extents();
+	while (!m_stop_requested) {
+		auto wrote_extents = flush_dirty_extents(true);
+
+		BEESNOTE("idle after writing " << wrote_extents << " of " << m_extents << " extents");
+
+		unique_lock<mutex> lock(m_dirty_mutex);
+		if (m_stop_requested) {
+			break;
+		}
+		if (m_dirty) {
+			m_dirty = false;
+		} else {
+			m_dirty_condvar.wait(lock);
+		}
 	}
+	BEESLOGDEBUG("Exited hash table writeback_loop");
 }
 
 static
@@ -186,7 +208,7 @@ void
 BeesHashTable::prefetch_loop()
 {
 	bool not_locked = true;
-	while (true) {
+	while (!m_stop_requested) {
 		size_t width = 64;
 		vector<size_t> occupancy(width, 0);
 		size_t occupied_count = 0;
@@ -196,7 +218,7 @@ BeesHashTable::prefetch_loop()
 		size_t toxic_count = 0;
 		size_t unaligned_eof_count = 0;
 
-		for (uint64_t ext = 0; ext < m_extents; ++ext) {
+		for (uint64_t ext = 0; ext < m_extents && !m_stop_requested; ++ext) {
 			BEESNOTE("prefetching hash table extent #" << ext << " of " << m_extents);
 			catch_all([&]() {
 				fetch_missing_extent_by_index(ext);
@@ -300,7 +322,7 @@ BeesHashTable::prefetch_loop()
 			m_stats_file.write(graph_blob.str());
 		});
 
-		if (not_locked) {
+		if (not_locked && !m_stop_requested) {
 			// Always do the mlock, whether shared or not
 			THROW_CHECK1(runtime_error, m_size, m_size > 0);
 			BEESLOGINFO("mlock(" << pretty(m_size) << ")...");
@@ -314,7 +336,12 @@ BeesHashTable::prefetch_loop()
 		}
 
 		BEESNOTE("idle " << BEES_HASH_TABLE_ANALYZE_INTERVAL << "s");
-		nanosleep(BEES_HASH_TABLE_ANALYZE_INTERVAL);
+		unique_lock<mutex> lock(m_stop_mutex);
+		if (m_stop_requested) {
+			BEESLOGDEBUG("Stop requested in hash table prefetch");
+			return;
+		}
+		m_stop_condvar.wait_for(lock, chrono::duration<double>(BEES_HASH_TABLE_ANALYZE_INTERVAL));
 	}
 }
 
@@ -704,13 +731,50 @@ BeesHashTable::BeesHashTable(shared_ptr<BeesContext> ctx, string filename, off_t
 
 BeesHashTable::~BeesHashTable()
 {
+	BEESLOGDEBUG("Destroy BeesHashTable");
 	if (m_cell_ptr && m_size) {
-		flush_dirty_extents();
+		// Dirty extents should have been flushed before now,
+		// e.g. in stop().  If that didn't happen, don't fall
+		// into the same trap (and maybe throw an exception) here.
+		// flush_dirty_extents(false);
 		catch_all([&]() {
 			DIE_IF_NON_ZERO(munmap(m_cell_ptr, m_size));
 			m_cell_ptr = nullptr;
 			m_size = 0;
 		});
 	}
+	BEESLOGDEBUG("BeesHashTable destroyed");
 }
 
+void
+BeesHashTable::stop()
+{
+	BEESNOTE("stopping BeesHashTable threads");
+	BEESLOGDEBUG("Stopping BeesHashTable threads");
+
+	unique_lock<mutex> lock(m_stop_mutex);
+	m_stop_requested = true;
+	m_stop_condvar.notify_all();
+	lock.unlock();
+
+	// Wake up hash writeback too
+	unique_lock<mutex> dirty_lock(m_dirty_mutex);
+	m_dirty_condvar.notify_all();
+	dirty_lock.unlock();
+
+	BEESNOTE("waiting for hash_prefetch thread");
+	BEESLOGDEBUG("Waiting for hash_prefetch thread");
+	m_prefetch_thread.join();
+
+	BEESNOTE("waiting for hash_writeback thread");
+	BEESLOGDEBUG("Waiting for hash_writeback thread");
+	m_writeback_thread.join();
+
+	if (m_cell_ptr && m_size) {
+		BEESLOGDEBUG("Flushing hash table");
+		BEESNOTE("flushing hash table");
+		flush_dirty_extents(false);
+	}
+
+	BEESLOGDEBUG("BeesHashTable stopped");
+}

src/bees-roots.cc

@@ -414,7 +414,7 @@ BeesRoots::crawl_thread()
 	// Monitor transid_max and wake up roots when it changes
 	BEESNOTE("tracking transid");
 	auto last_count = m_transid_re.count();
-	while (true) {
+	while (!m_stop_requested) {
 		// Measure current transid
 		catch_all([&]() {
 			m_transid_re.update(transid_max_nocache());
@@ -441,7 +441,12 @@ BeesRoots::crawl_thread()
 		auto poll_time = m_transid_re.seconds_for(m_transid_factor);
 		BEESLOGDEBUG("Polling " << poll_time << "s for next " << m_transid_factor << " transid " << m_transid_re);
 		BEESNOTE("waiting " << poll_time << "s for next " << m_transid_factor << " transid " << m_transid_re);
-		nanosleep(poll_time);
+		unique_lock<mutex> lock(m_stop_mutex);
+		if (m_stop_requested) {
+			BEESLOGDEBUG("Stop requested in crawl thread");
+			break;
+		}
+		m_stop_condvar.wait_for(lock, chrono::duration<double>(poll_time));
 	}
 }
 
@@ -456,7 +461,16 @@ BeesRoots::writeback_thread()
 			state_save();
 		});
 
-		nanosleep(BEES_WRITEBACK_INTERVAL);
+		unique_lock<mutex> lock(m_stop_mutex);
+		if (m_stop_requested) {
+			BEESLOGDEBUG("Stop requested in writeback thread");
+			catch_all([&]() {
+				BEESNOTE("flushing crawler state");
+				state_save();
+			});
+			return;
+		}
+		m_stop_condvar.wait_for(lock, chrono::duration<double>(BEES_WRITEBACK_INTERVAL));
 	}
 }
 
@@ -574,6 +588,7 @@ BeesRoots::BeesRoots(shared_ptr<BeesContext> ctx) :
 		catch_all([&]() {
 			state_load();
 		});
+
 		m_writeback_thread.exec([&]() {
 			writeback_thread();
 		});
@@ -581,6 +596,29 @@ BeesRoots::BeesRoots(shared_ptr<BeesContext> ctx) :
 	});
 }
 
+void
+BeesRoots::stop()
+{
+	BEESLOGDEBUG("BeesRoots stop requested");
+	BEESNOTE("stopping BeesRoots");
+	unique_lock<mutex> lock(m_stop_mutex);
+	m_stop_requested = true;
+	m_stop_condvar.notify_all();
+	lock.unlock();
+
+	// Stop crawl writeback first because we will break progress
+	// state tracking when we cancel the TaskMaster queue
+	BEESLOGDEBUG("Waiting for crawl writeback");
+	BEESNOTE("waiting for crawl_writeback thread");
+	m_writeback_thread.join();
+
+	BEESLOGDEBUG("Waiting for crawl thread");
+	BEESNOTE("waiting for crawl_thread thread");
+	m_crawl_thread.join();
+
+	BEESLOGDEBUG("BeesRoots stopped");
+}
+
 Fd
 BeesRoots::open_root_nocache(uint64_t rootid)
 {

src/bees.cc

@@ -531,10 +531,16 @@ BeesTempFile::resize(off_t offset)
 	BEESCOUNTADD(tmp_resize_ms, resize_timer.age() * 1000);
 }
 
+BeesTempFile::~BeesTempFile()
+{
+	BEESLOGDEBUG("Destructing BeesTempFile " << this);
+}
+
 BeesTempFile::BeesTempFile(shared_ptr<BeesContext> ctx) :
 	m_ctx(ctx),
 	m_end_offset(0)
 {
+	BEESLOGDEBUG("Constructing BeesTempFile " << this);
 	create();
 }
 
@@ -640,6 +646,77 @@ BeesTempFile::make_copy(const BeesFileRange &src)
 	return rv;
 }
 
+static
+ostream &
+operator<<(ostream &os, const siginfo_t &si)
+{
+	return os << "siginfo_t { "
+		<< "signo = " << si.si_signo << " (" << signal_ntoa(si.si_signo) << "), "
+		<< "errno = " << si.si_errno << ", "
+		<< "code = " << si.si_code << ", "
+		// << "trapno = " << si.si_trapno << ", "
+		<< "pid = " << si.si_pid << ", "
+		<< "uid = " << si.si_uid << ", "
+		<< "status = " << si.si_status << ", "
+		<< "utime = " << si.si_utime << ", "
+		<< "stime = " << si.si_stime << ", "
+		// << "value = " << si.si_value << ", "
+		<< "int = " << si.si_int << ", "
+		<< "ptr = " << si.si_ptr << ", "
+		<< "overrun = " << si.si_overrun << ", "
+		<< "timerid = " << si.si_timerid << ", "
+		<< "addr = " << si.si_addr << ", "
+		<< "band = " << si.si_band << ", "
+		<< "fd = " << si.si_fd << ", "
+		<< "addr_lsb = " << si.si_addr_lsb << ", "
+		<< "lower = " << si.si_lower << ", "
+		<< "upper = " << si.si_upper << ", "
+		// << "pkey = " << si.si_pkey << ", "
+		<< "call_addr = " << si.si_call_addr << ", "
+		<< "syscall = " << si.si_syscall << ", "
+		<< "arch = " << si.si_arch
+		<< " }";
+}
+
+static sigset_t new_sigset, old_sigset;
+
+void
+block_term_signal()
+{
+	BEESLOGDEBUG("Masking signals");
+
+	DIE_IF_NON_ZERO(sigemptyset(&new_sigset));
+	DIE_IF_NON_ZERO(sigaddset(&new_sigset, SIGTERM));
+	DIE_IF_NON_ZERO(sigaddset(&new_sigset, SIGINT));
+	DIE_IF_NON_ZERO(sigprocmask(SIG_BLOCK, &new_sigset, &old_sigset));
+}
+
+void
+wait_for_term_signal()
+{
+	BEESNOTE("waiting for signals");
+	BEESLOGDEBUG("Waiting for signals...");
+	siginfo_t info;
+
+	// Ironically, sigwaitinfo can be interrupted by a signal.
+	while (true) {
+		const int rv = sigwaitinfo(&new_sigset, &info);
+		if (rv == -1) {
+			if (errno == EINTR) {
+				BEESLOGDEBUG("Restarting sigwaitinfo");
+				continue;
+			}
+			THROW_ERRNO("sigwaitinfo errno = " << errno);
+		} else {
+			BEESLOGNOTICE("Received signal " << rv << " info " << info);
+			// Unblock so we die immediately if signalled again
+			DIE_IF_NON_ZERO(sigprocmask(SIG_BLOCK, &old_sigset, &new_sigset));
+			break;
+		}
+	}
+	BEESLOGDEBUG("Signal catcher exiting");
+}
+
 int
 bees_main(int argc, char *argv[])
 {
@@ -656,6 +733,10 @@ bees_main(int argc, char *argv[])
 
 	THROW_CHECK1(invalid_argument, argc, argc >= 0);
 
+	// Have to block signals now before we create a bunch of threads
+	// so the threads will also have the signals blocked.
+	block_term_signal();
+
 	// Create a context so we can apply configuration to it
 	shared_ptr<BeesContext> bc = make_shared<BeesContext>();
 
@@ -813,12 +894,14 @@ bees_main(int argc, char *argv[])
 	// Create a context and start crawlers
 	bc->set_root_path(argv[optind++]);
 
-	BeesThread status_thread("status", [&]() {
-		bc->dump_status();
-	});
+	// Start crawlers
+	bc->start();
 
 	// Now we just wait forever
-	bc->show_progress();
+	wait_for_term_signal();
+
+	// Shut it down
+	bc->stop();
 
 	// That is all.
 	return EXIT_SUCCESS;

src/bees.h

@@ -410,6 +410,8 @@ public:
 	BeesHashTable(shared_ptr<BeesContext> ctx, string filename, off_t size = BLOCK_SIZE_HASHTAB_EXTENT);
 	~BeesHashTable();
 
+	void stop();
+
 	vector<Cell>	find_cell(HashType hash);
 	bool		push_random_hash_addr(HashType hash, AddrType addr);
 	void		erase_hash_addr(HashType hash, AddrType addr);
@@ -444,6 +446,12 @@ private:
 	// Mutex/condvar for the writeback thread
 	mutex			m_dirty_mutex;
 	condition_variable	m_dirty_condvar;
+	bool			m_dirty;
+
+	// Mutex/condvar to stop
+	mutex			m_stop_mutex;
+	condition_variable	m_stop_condvar;
+	bool			m_stop_requested = false;
 
 	// Per-extent structures
 	struct ExtentMetaData {
@@ -463,7 +471,7 @@ private:
 	void fetch_missing_extent_by_hash(HashType hash);
 	void fetch_missing_extent_by_index(uint64_t extent_index);
 	void set_extent_dirty_locked(uint64_t extent_index);
-	void flush_dirty_extents();
+	size_t flush_dirty_extents(bool slowly);
 	bool flush_dirty_extent(uint64_t extent_index);
 
 	size_t			hash_to_extent_index(HashType ht);
@@ -529,6 +537,10 @@ class BeesRoots : public enable_shared_from_this<BeesRoots> {
 	bool					m_workaround_btrfs_send = false;
 	LRUCache<bool, uint64_t>		m_root_ro_cache;
 
+	mutex					m_stop_mutex;
+	condition_variable			m_stop_condvar;
+	bool					m_stop_requested = false;
+
 	void insert_new_crawl();
 	void insert_root(const BeesCrawlState &bcs);
 	Fd open_root_nocache(uint64_t root);
@@ -557,6 +569,9 @@ friend class BeesCrawl;
 
 public:
 	BeesRoots(shared_ptr<BeesContext> ctx);
+	void start();
+	void stop();
+
 	Fd open_root(uint64_t root);
 	Fd open_root_ino(uint64_t root, uint64_t ino);
 	Fd open_root_ino(const BeesFileId &bfi) { return open_root_ino(bfi.root(), bfi.ino()); }
@@ -651,6 +666,7 @@ class BeesTempFile {
 	void resize(off_t new_end_offset);
 
 public:
+	~BeesTempFile();
 	BeesTempFile(shared_ptr<BeesContext> ctx);
 	BeesFileRange make_hole(off_t count);
 	BeesFileRange make_copy(const BeesFileRange &src);
@@ -677,6 +693,10 @@ struct BeesResolveAddrResult {
 	bool is_toxic() const { return m_is_toxic; }
 };
 
+struct BeesHalt : exception {
+	const char *what() const noexcept override;
+};
+
 class BeesContext : public enable_shared_from_this<BeesContext> {
 	shared_ptr<BeesContext>				m_parent_ctx;
 
@@ -685,7 +705,6 @@ class BeesContext : public enable_shared_from_this<BeesContext> {
 	shared_ptr<BeesFdCache>				m_fd_cache;
 	shared_ptr<BeesHashTable>			m_hash_table;
 	shared_ptr<BeesRoots>				m_roots;
-
 	map<thread::id, shared_ptr<BeesTempFile>>	m_tmpfiles;
 
 	LRUCache<BeesResolveAddrResult, BeesAddress>	m_resolve_cache;
@@ -701,6 +720,14 @@ class BeesContext : public enable_shared_from_this<BeesContext> {
 
 	LockSet<uint64_t>				m_extent_lock_set;
 
+	mutable mutex					m_stop_mutex;
+	condition_variable				m_stop_condvar;
+	bool						m_stop_requested = false;
+	bool						m_stop_status = false;
+
+	BeesThread					m_progress_thread;
+	BeesThread					m_status_thread;
+
 	void set_root_fd(Fd fd);
 
 	BeesResolveAddrResult resolve_addr_uncached(BeesAddress addr);
@@ -733,6 +760,10 @@ public:
 	void dump_status();
 	void show_progress();
 
+	void start();
+	void stop();
+	bool stop_requested() const;
+
 	shared_ptr<BeesFdCache> fd_cache();
 	shared_ptr<BeesHashTable> hash_table();
 	shared_ptr<BeesRoots> roots();