[snowpatch] [PATCH] jenkins: add wait_build() method to poll Jenkins build status at intervals

[Andrew Donnellan]

Right now, after the Jenkins build is triggered, we query the build status
continuously. This is bad, and it works the CPU rather hard.

Instead, add a new method to poll every 5 seconds and put the thread to
sleep in the meantime.

Closes: #16 ("Don't spin when waiting for Jenkins results")
Signed-off-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>

---

Probably a couple of other places where we need to do something similar.
---
 src/jenkins.rs | 16 ++++++++++++++++
 src/main.rs    | 11 ++---------
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/src/jenkins.rs b/src/jenkins.rs
index 9983396..38a8664 100644
--- a/src/jenkins.rs
+++ b/src/jenkins.rs
@@ -25,11 +25,16 @@ extern crate url;
 extern crate rustc_serialize;
 
 use std::io::Read;
+use std::time::Duration;
+use std::thread::sleep;
 
 use hyper::Client;
 use hyper::header::Location;
 use rustc_serialize::json::Json;
 
+// Constants
+const JENKINS_POLLING_INTERVAL: u64 = 5000; // Polling interval in milliseconds
+
 // Jenkins API definitions
 
 pub trait CIBackend { // TODO: Separate out
@@ -98,4 +103,15 @@ impl<'a> JenkinsBackend<'a> {
             false => JenkinsBuildStatus::Done,
         }
     }
+
+    pub fn wait_build(&self, build_url: &str) -> JenkinsBuildStatus {
+        // TODO: Implement a timeout?
+        loop {
+            match self.get_build_status(&build_url) {
+                JenkinsBuildStatus::Done => return JenkinsBuildStatus::Done,
+                _ => { },
+            }
+            sleep(Duration::from_millis(JENKINS_POLLING_INTERVAL));
+        }
+    }
 }
diff --git a/src/main.rs b/src/main.rs
index 01524dd..b18206c 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -43,7 +43,7 @@ mod patchwork;
 use patchwork::{PatchworkServer, TestState, TestResult};
 
 mod jenkins;
-use jenkins::{JenkinsBackend, CIBackend, JenkinsBuildStatus};
+use jenkins::{JenkinsBackend, CIBackend};
 
 mod settings;
 use settings::{Config, Project};
@@ -109,14 +109,7 @@ fn run_tests(settings: &Config, project: &Project, tag: &str) -> Vec<TestResult>
             }
         }
         println!("Build URL: {}", build_url_real);
-
-        loop {
-            let status = jenkins.get_build_status(&build_url_real);
-            match status  {
-                JenkinsBuildStatus::Done => break,
-                _ => {}
-            }
-        }
+        jenkins.wait_build(&build_url_real);
         println!("Job done!");
         results.push(TestResult {
             test_name: job_name.to_string(),
-- 
Andrew Donnellan              Software Engineer, OzLabs
andrew.donnellan at au1.ibm.com  Australia Development Lab, Canberra
+61 2 6201 8874 (work)        IBM Australia Limited