X-Git-Url: https://git.sesse.net/?p=cubemap;a=blobdiff_plain;f=thread.h;h=728df27cd38002881f5270315344c1616307fc42;hp=9c9bdc6d3ba79b49728c0398521382d6d33bb9f0;hb=845934ca50eee40884e8cc85ea81eb310efa5ca3;hpb=94561762b1294b76508eb5554aedbb56fcaececc;ds=sidebyside

diff --git a/thread.h b/thread.h
index 9c9bdc6..728df27 100644
--- a/thread.h
+++ b/thread.h
@@ -1,12 +1,19 @@
 #ifndef _THREAD_H
 #define _THREAD_H
 
+#include <signal.h>
 #include <pthread.h>
 
-// A rather generic thread class with start/stop functionality.
-// NOTE: stop is somewhat racy (there's no guaranteed breakout from syscalls),
-// since signals don't stick. We'll need to figure out something more
-// intelligent later, probably based on sending a signal to an fd.
+struct timespec;
+
+// A thread class with start/stop and signal functionality.
+//
+// SIGUSR1 is blocked during execution of do_work(), so that you are guaranteed
+// to receive it when doing wait_for_activity(), and never elsewhere. This means
+// that you can test whatever status flags you'd want before calling
+// wait_for_activity(), and then be sure that it actually returns immediately
+// if a SIGUSR1 (ie., wakeup()) happened, even if it were sent between your test
+// and the wait_for_activity() call.
 
 class Thread {
 public:
@@ -15,15 +22,39 @@ public:
 	void stop();
 
 protected:
-	// Recovers the this pointer, and calls do_work().
+	// Recovers the this pointer, blocks SIGUSR1, and calls do_work().
 	static void *do_work_thunk(void *arg);
 
 	virtual void do_work() = 0;
 
-	volatile bool should_stop;
+	// Waits until there is activity of the given type on <fd> (or an error),
+	// or until a wakeup. Returns true if there was actually activity on
+	// the file descriptor.
+	//
+	// If fd is -1, wait until a wakeup or timeout.
+	// if timeout_ts is NULL, there is no timeout.
+	bool wait_for_activity(int fd, short events, const timespec *timeout_ts);
+
+	// Wait until a wakeup.
+	void wait_for_wakeup(const timespec *timeout_ts) { wait_for_activity(-1, 0, timeout_ts); }
+
+	// Make wait_for_activity() return. Note that this is a relatively expensive
+	// operation.
+	void wakeup();
+
+	bool should_stop();
+
+	// The signal set as it were before we blocked SIGUSR1.
+	sigset_t sigset_without_usr1_block;
 
 private:
 	pthread_t worker_thread;
+
+	// Protects should_stop_status.
+	pthread_mutex_t should_stop_mutex;
+
+	// If this is set, the thread should return as soon as possible from do_work().
+	bool should_stop_status;
 };
 
 #endif  // !defined(_THREAD_H)