Print heap histogram

Also:
* Avoid unhelpful compiler warnings
* Capture common code in a macro

Note: it would have been nice to alias the closure type, but
rust-lang/rfcs#1733 is not yet implemented and macros
can't cope (rust-lang/rust#24010).

src/agentcontroller/controller.rs

@@ -15,6 +15,7 @@
  */
 
 pub struct AgentController<'a> {
+    #[allow(dead_code)] // TODO: revisit this once port is complete
     jvmti: ::env::JvmTiEnv,
     heuristic: Box<super::Heuristic + 'a>,
     actions: Vec<Box<super::Action>>
@@ -126,9 +127,9 @@ mod tests {
         ac.on_oom(dummy_jni_env(), 0);
     }
 
-    unsafe extern "C" fn test_get_env(vm: *mut ::jvmti::JavaVM,
-                                      penv: *mut *mut ::std::os::raw::c_void,
-                                      version: ::jvmti::jint)
+    unsafe extern "C" fn test_get_env(_: *mut ::jvmti::JavaVM,
+                                      _: *mut *mut ::std::os::raw::c_void,
+                                      _: ::jvmti::jint)
                                       -> ::jvmti::jint {
         0
     }

src/agentcontroller/heaphistogram.rs

@@ -14,19 +14,149 @@
  * limitations under the License.
  */
 
-pub struct HeapHistogram {
-    jvmti: ::env::JvmTiEnv,
+use env::JvmTI;
+use std::io::Write;
+use std::io::stdout;
+use heap::tagger::Tagger;
+use heap::tagger::Tag;
+use heap::stats::Stats;
+use heap::stats::Record;
+use heap::stats::Print;
+
+pub struct HeapHistogram<T: JvmTI + Clone> {
+    jvmti: T,
 }
 
-impl HeapHistogram {
-    pub fn new(jvmti: ::env::JvmTiEnv) -> Result<Self, ::jvmti::jint> {
+impl<T: JvmTI + Clone> HeapHistogram<T> {
+    pub fn new(mut jvmti: T) -> Result<Self, ::jvmti::jint> {
+        jvmti.enable_object_tagging()?;
         Ok(Self {
-            jvmti: jvmti
+            jvmti: jvmti.clone(),
         })
     }
+
+    fn print(&self, writer: &mut Write) {
+        let mut tagger = Tagger::new();
+
+        // Tag all loaded classes so we can determine each object's class signature during heap traversal.
+        self.jvmti.tag_loaded_classes(&mut tagger);
+
+        let mut heap_stats = Stats::new();
+
+        // Traverse the live heap and add objects to the heap stats.
+        self.jvmti.traverse_live_heap(|class_tag: ::jvmti::jlong, size: ::jvmti::jlong| {
+            if let Some(sig) = tagger.class_signature(class_tag) {
+                heap_stats.recordObject(sig, size);
+            }
+        });
+
+        heap_stats.print(writer);
+    }
+}
+
+impl<T: JvmTI + Clone> super::Action for HeapHistogram<T> {
+    fn on_oom(&self, _: ::env::JniEnv, _: ::jvmti::jint) {
+        self.print(&mut stdout());
+    }
 }
 
-impl super::Action for HeapHistogram {
-    fn on_oom(&self, jni_env: ::env::JniEnv, resource_exhaustion_flags: ::jvmti::jint) {
+#[cfg(test)]
+mod tests {
+    use super::HeapHistogram;
+    use ::env::JvmTI;
+    use ::env::FnResourceExhausted;
+    use std::cell::RefCell;
+    use std::sync::Mutex;
+    use ::env::RawMonitorId;
+    use ::heap::tagger::Tag;
+
+    const test_error_code: ::jvmti::jint = 54;
+
+    #[test]
+    fn new_calls_enable_object_tagging() {
+        let mockJvmti = MockJvmti::new();
+        let hh = HeapHistogram::new(mockJvmti);
+        assert!(hh.is_ok());
+        assert!((hh.unwrap().jvmti as MockJvmti).object_tagging_enabled);
+    }
+
+    #[test]
+    fn new_percolates_enable_object_tagging_failure() {
+        let mut mockJvmti = MockJvmti::new();
+        mockJvmti.object_tagging_enabled_result = Err(test_error_code);
+        let hh = HeapHistogram::new(mockJvmti);
+        assert!(hh.is_err());
+        assert_eq!(hh.err().unwrap(), test_error_code);
+    }
+
+    #[test]
+    fn print_works() {
+        let mockJvmti = MockJvmti::new();
+        let hh = HeapHistogram::new(mockJvmti);
+
+        let mut buff: Vec<u8> = Vec::new();
+        hh.unwrap().print(&mut buff);
+        let string_buff = String::from_utf8(buff).expect("invalid UTF-8");
+        assert_eq!(string_buff, "| Instance Count | Total Bytes | Class Name |\n| 2              | 200         | sig2       |\n| 1              | 10          | sig1       |\n".to_string());
+
+    }
+
+    #[derive(Clone, Copy, Default)]
+    struct Classes {
+        t1: ::jvmti::jlong,
+        t2: ::jvmti::jlong
+    }
+
+    #[derive(Clone)]
+    struct MockJvmti {
+        pub object_tagging_enabled_result: Result<(), ::jvmti::jint>,
+        pub object_tagging_enabled: bool,
+        classes: RefCell<Classes>
+    }
+
+    impl MockJvmti {
+        fn new() -> MockJvmti {
+            MockJvmti {
+                object_tagging_enabled_result: Ok(()),
+                object_tagging_enabled: false,
+                classes: RefCell::new(Default::default())
+            }
+        }
+    }
+
+    impl JvmTI for MockJvmti {
+        fn create_raw_monitor(&mut self, name: String, monitor: &Mutex<RawMonitorId>) -> Result<(), ::jvmti::jint> {
+            unimplemented!()
+        }
+
+        fn raw_monitor_enter(&mut self, monitor: &Mutex<RawMonitorId>) -> Result<(), ::jvmti::jint> {
+            unimplemented!()
+        }
+
+        fn raw_monitor_exit(&mut self, monitor: &Mutex<RawMonitorId>) -> Result<(), ::jvmti::jint> {
+            unimplemented!()
+        }
+
+        fn on_resource_exhausted(&mut self, callback: FnResourceExhausted) -> Result<(), ::jvmti::jint> {
+            unimplemented!()
+        }
+
+        fn enable_object_tagging(&mut self) -> Result<(), ::jvmti::jint> {
+            self.object_tagging_enabled = true;
+            self.object_tagging_enabled_result
+        }
+
+        fn tag_loaded_classes(&self, tagger: &mut Tag) {
+            let mut c = self.classes.borrow_mut();
+            c.t1 = tagger.class_tag(&"sig1".to_string());
+            c.t2 = tagger.class_tag(&"sig2".to_string());
+        }
+
+        fn traverse_live_heap<F>(&self, mut closure: F) where F: FnMut(::jvmti::jlong, ::jvmti::jlong) {
+            let c = self.classes.borrow();
+            closure(c.t1, 10);
+            closure(c.t2, 100);
+            closure(c.t2, 100);
+        }
     }
 }

src/agentcontroller/kill.rs

@@ -30,6 +30,7 @@ impl Kill {
         }
     }
 
+    #[cfg(test)]
     pub fn setSignal(&mut self, signal: c_int) {
         self.signal = signal;
     }
@@ -93,7 +94,7 @@ mod tests {
                                                 signal::SaFlags::empty(),
                                                 signal::SigSet::empty());
         unsafe {
-            signal::sigaction(signal::SIGUSR1, &sig_action);
+            signal::sigaction(signal::SIGUSR1, &sig_action).unwrap();
         }
     }
 }

src/agentcontroller/threshold.rs

@@ -90,7 +90,7 @@ mod tests {
         assert!(!threshold.on_oom());
         assert!(!threshold.on_oom());
 
-        thread::sleep(time::Duration::from_millis(1000));
+        thread::sleep(time::Duration::from_millis(1100));
 
         assert!(!threshold.on_oom());
         assert!(!threshold.on_oom());