Add rwlocks.

examples/evlocks.janet

@@ -0,0 +1,45 @@
+(defn sleep
+  "Sleep the entire thread, not just a single fiber."
+  [n]
+  (os/sleep (* 0.1 n)))
+
+(defn work [lock n]
+  (ev/acquire-lock lock)
+  (print "working " n "...")
+  (sleep n)
+  (print "done working...")
+  (ev/release-lock lock))
+
+(defn reader
+  [rwlock n]
+  (ev/acquire-rlock rwlock)
+  (print "reading " n "...")
+  (sleep n)
+  (print "done reading " n "...")
+  (ev/release-rlock rwlock))
+
+(defn writer
+  [rwlock n]
+  (ev/acquire-wlock rwlock)
+  (print "writing " n "...")
+  (sleep n)
+  (print "done writing...")
+  (ev/release-wlock rwlock))
+
+(defn test-lock
+  []
+  (def lock (ev/lock))
+  (for i 3 7
+    (ev/spawn-thread
+      (work lock i))))
+
+(defn test-rwlock
+  []
+  (def rwlock (ev/rwlock))
+  (for i 0 20
+    (if (> 0.1 (math/random))
+      (ev/spawn-thread (writer rwlock i))
+      (ev/spawn-thread (reader rwlock i)))))
+
+(test-rwlock)
+(test-lock)