1 files changed, 82 insertions, 0 deletions
diff --git a/misc/thread_tools.h b/misc/thread_tools.h
new file mode 100644
index 0000000000..89d84ce0b6
--- /dev/null
+++ b/misc/thread_tools.h
@@ -0,0 +1,82 @@
+#pragma once
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <pthread.h>
+
+// This is basically a single-shot semaphore, intended as light-weight solution
+// for just making a thread wait for another thread.
+struct mp_waiter {
+    // All fields are considered private. Use MP_WAITER_INITIALIZER to init.
+    pthread_mutex_t lock;
+    pthread_cond_t wakeup;
+    bool done;
+    uintptr_t value;
+};
+
+// Initialize a mp_waiter object for use with mp_waiter_*().
+#define MP_WAITER_INITIALIZER { \
+    .lock = PTHREAD_MUTEX_INITIALIZER, \
+    .wakeup = PTHREAD_COND_INITIALIZER, \
+    }
+
+// Block until some other thread calls mp_waiter_wakeup(). The function returns
+// the value argument of that wakeup call. After this, the waiter object must
+// not be used anymore. Although you can reinit it with MP_WAITER_INITIALIZER
+// (then you must make sure nothing calls mp_waiter_wakeup() before this).
+uintptr_t mp_waiter_wait(struct mp_waiter *waiter);
+
+// Unblock the thread waiting with mp_waiter_wait(), and make it return the
+// provided value. If the other thread did not enter that call yet, it will
+// return immediately once it does (mp_waiter_wakeup() always returns
+// immediately). Calling this more than once is not allowed.
+void mp_waiter_wakeup(struct mp_waiter *waiter, uintptr_t value);
+
+// Query whether the waiter was woken up. If true, mp_waiter_wait() will return
+// immediately. This is useful if you want to use another way to block and
+// wakeup (in parallel to mp_waiter).
+// You still need to call mp_waiter_wait() to free resources.
+bool mp_waiter_poll(struct mp_waiter *waiter);
+
+// Basically a binary semaphore that supports signaling the semaphore value to
+// a bunch of other complicated mechanisms (such as wakeup pipes). It was made
+// for aborting I/O and thus has according naming.
+struct mp_cancel;
+
+struct mp_cancel *mp_cancel_new(void *talloc_ctx);
+
+// Request abort.
+void mp_cancel_trigger(struct mp_cancel *c);
+
+// Return whether the caller should abort.
+// For convenience, c==NULL is allowed.
+bool mp_cancel_test(struct mp_cancel *c);
+
+// Wait until the even is signaled. If the timeout (in seconds) expires, return
+// false. timeout==0 polls, timeout<0 waits forever.
+bool mp_cancel_wait(struct mp_cancel *c, double timeout);
+
+// Restore original state. (Allows reusing a mp_cancel.)
+void mp_cancel_reset(struct mp_cancel *c);
+
+// Add a callback to invoke when mp_cancel gets triggered. If it's already
+// triggered, call it from mp_cancel_add_cb() directly. May be called multiple
+// times even if the trigger state changes; not called if it resets. In all
+// cases, this may be called with internal locks held (either in mp_cancel, or
+// other locks held by whoever calls mp_cancel_trigger()).
+// There is only one callback. Create a slave mp_cancel to get a private one.
+void mp_cancel_set_cb(struct mp_cancel *c, void (*cb)(void *ctx), void *ctx);
+
+// If parent gets triggered, automatically trigger slave. There is only 1
+// parent; setting NULL clears the parent. Freeing slave also automatically
+// ends the parent link, but the parent mp_cancel must remain valid until the
+// slave is manually removed or destroyed. Destroying a mp_cancel that still
+// has slaves is an error.
+void mp_cancel_set_parent(struct mp_cancel *slave, struct mp_cancel *parent);
+
+// win32 "Event" HANDLE that indicates the current mp_cancel state.
+void *mp_cancel_get_event(struct mp_cancel *c);
+
+// The FD becomes readable if mp_cancel_test() would return true.
+// Don't actually read from it, just use it for poll().
+int mp_cancel_get_fd(struct mp_cancel *c);