examples/threads: Drop lock early

Demonstrate releasing the thread safe context lock as soon as we're done
accessing redis data structures. Earlier, the lock was being held until
the value was in scope, which included the sleep time.

Author: prashanthpai

examples/threads.rs

@@ -1,18 +1,21 @@
 #[macro_use]
 extern crate redis_module;
 
-use bitflags::_core::time::Duration;
-use redis_module::{Context, RedisError, RedisResult, ThreadSafeContext};
+use redis_module::{Context, RedisResult, ThreadSafeContext};
+use std::mem::drop;
 use std::thread;
+use std::time::Duration;
 
 fn threads(_: &Context, _args: Vec<String>) -> RedisResult {
     thread::spawn(move || {
         let thread_ctx = ThreadSafeContext::new();
 
-        for _ in 0..2 {
+        loop {
             let ctx = thread_ctx.lock();
             ctx.call("INCR", &["threads"]).unwrap();
-            thread::sleep(Duration::from_millis(100));
+            // release the lock as soon as we're done accessing redis memory
+            drop(ctx);
+            thread::sleep(Duration::from_millis(1000));
         }
     });