Cleaner controls between Vpn and init services.

Change-Id: I35edf054f4a1190f7fb7b4c48ee832e899c9528b

1 files changed, 117 insertions, 6 deletions

diff --git a/core/java/android/os/SystemService.java b/core/java/android/os/SystemService.java
index da27db55c49a..db58012d47ab 100644
--- a/core/java/android/os/SystemService.java
+++ b/core/java/android/os/SystemService.java
@@ -16,15 +16,53 @@
 
 package android.os;
 
-/** @hide */
-public class SystemService
-{
-        /** Request that the init daemon start a named service. */
+import com.google.android.collect.Maps;
+
+import java.util.HashMap;
+import java.util.concurrent.TimeoutException;
+
+/**
+ * Controls and utilities for low-level {@code init} services.
+ *
+ * @hide
+ */
+public class SystemService {
+
+    private static HashMap<String, State> sStates = Maps.newHashMap();
+
+    /**
+     * State of a known {@code init} service.
+     */
+    public enum State {
+        RUNNING("running"),
+        STOPPING("stopping"),
+        STOPPED("stopped"),
+        RESTARTING("restarting");
+
+        State(String state) {
+            sStates.put(state, this);
+        }
+    }
+
+    private static Object sPropertyLock = new Object();
+
+    static {
+        SystemProperties.addChangeCallback(new Runnable() {
+            @Override
+            public void run() {
+                synchronized (sPropertyLock) {
+                    sPropertyLock.notifyAll();
+                }
+            }
+        });
+    }
+
+    /** Request that the init daemon start a named service. */
     public static void start(String name) {
         SystemProperties.set("ctl.start", name);
     }
-    
-        /** Request that the init daemon stop a named service. */
+
+    /** Request that the init daemon stop a named service. */
     public static void stop(String name) {
         SystemProperties.set("ctl.stop", name);
     }
@@ -33,4 +71,77 @@ public class SystemService
     public static void restart(String name) {
         SystemProperties.set("ctl.restart", name);
     }
+
+    /**
+     * Return current state of given service.
+     */
+    public static State getState(String service) {
+        final String rawState = SystemProperties.get("init.svc." + service);
+        final State state = sStates.get(rawState);
+        if (state != null) {
+            return state;
+        } else {
+            throw new IllegalStateException("Service " + service + " in unknown state " + rawState);
+        }
+    }
+
+    /**
+     * Check if given service is {@link State#STOPPED}.
+     */
+    public static boolean isStopped(String service) {
+        return State.STOPPED.equals(getState(service));
+    }
+
+    /**
+     * Check if given service is {@link State#RUNNING}.
+     */
+    public static boolean isRunning(String service) {
+        return State.RUNNING.equals(getState(service));
+    }
+
+    /**
+     * Wait until given service has entered specific state.
+     */
+    public static void waitForState(String service, State state, long timeoutMillis)
+            throws TimeoutException {
+        final long endMillis = SystemClock.elapsedRealtime() + timeoutMillis;
+        while (true) {
+            synchronized (sPropertyLock) {
+                final State currentState = getState(service);
+                if (state.equals(currentState)) {
+                    return;
+                }
+
+                if (SystemClock.elapsedRealtime() >= endMillis) {
+                    throw new TimeoutException("Service " + service + " currently " + currentState
+                            + "; waited " + timeoutMillis + "ms for " + state);
+                }
+
+                try {
+                    sPropertyLock.wait(timeoutMillis);
+                } catch (InterruptedException e) {
+                }
+            }
+        }
+    }
+
+    /**
+     * Wait until any of given services enters {@link State#STOPPED}.
+     */
+    public static void waitForAnyStopped(String... services)  {
+        while (true) {
+            synchronized (sPropertyLock) {
+                for (String service : services) {
+                    if (State.STOPPED.equals(getState(service))) {
+                        return;
+                    }
+                }
+
+                try {
+                    sPropertyLock.wait();
+                } catch (InterruptedException e) {
+                }
+            }
+        }
+    }
 }