Add extcon specific UEventObserver
Change-Id: If751f7264eebdedd9a23f8dbb33e1cc1fab00951
Test: m -j services.core
Bug: 116011465
diff --git a/services/core/java/com/android/server/ExtconStateObserver.java b/services/core/java/com/android/server/ExtconStateObserver.java
new file mode 100644
index 0000000..6b561c7
--- /dev/null
+++ b/services/core/java/com/android/server/ExtconStateObserver.java
@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.server;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.os.FileUtils;
+import android.util.Slog;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+
+/**
+ * A specialized ExtconUEventObserver that on receiving a {@link UEvent} calls {@link
+ * #updateState(ExtconInfo, String, S)} with the value of{@link #parseState(ExtconInfo, String)}.
+ *
+ * @param <S> the type of state to parse and update
+ * @hide
+ */
+public abstract class ExtconStateObserver<S> extends ExtconUEventObserver {
+ private static final String TAG = "ExtconStateObserver";
+ private static final boolean LOG = false;
+
+ /**
+ * Parses the current state from the state file for {@code extconInfo} and calls {@link
+ * #updateState(ExtconInfo, String, Object)}
+ *
+ * @param extconInfo the extconInfo to update state for
+ * @see #parseState(ExtconInfo, String)
+ * @see ExtconInfo#getStatePath()
+ */
+ public void updateStateFromFile(ExtconInfo extconInfo) {
+ String statePath = extconInfo.getStatePath();
+ try {
+ S state =
+ parseState(
+ extconInfo,
+ FileUtils.readTextFile(new File(statePath), 0, null).trim());
+ if (state != null) {
+ updateState(extconInfo, extconInfo.getName(), state);
+ }
+ } catch (FileNotFoundException e) {
+ Slog.w(TAG, statePath + " not found while attempting to determine initial state", e);
+ } catch (IOException e) {
+ Slog.e(
+ TAG,
+ "Error reading " + statePath + " while attempting to determine initial state ",
+ e);
+ }
+ }
+
+ @Override
+ public void onUEvent(ExtconInfo extconInfo, UEvent event) {
+ if (LOG) Slog.d(TAG, extconInfo.getName() + " UEVENT: " + event);
+ String name = event.get("NAME");
+ S state = parseState(extconInfo, event.get("STATE"));
+ if (state != null) {
+ updateState(extconInfo, name, state);
+ }
+ }
+
+ /**
+ * Subclasses of ExtconStateObserver should override this method update state for {@code
+ * exconInfo} from an {@code UEvent}.
+ *
+ * @param extconInfo the external connection
+ * @param eventName the {@code NAME} of the {@code UEvent}
+ * @param state the{@code STATE} as parsed by {@link #parseState(ExtconInfo, String)}.
+ */
+ public abstract void updateState(ExtconInfo extconInfo, String eventName, @NonNull S state);
+
+ /**
+ * Subclasses of ExtconStateObserver should override this method to parse the {@code STATE} from
+ * an UEvent.
+ *
+ * @param extconInfo that matches the {@code DEVPATH} of {@code event}
+ * @param state the {@code STATE} from a {@code UEvent}.
+ * @return the parsed state. Return null if the state can not be parsed.
+ */
+ @Nullable
+ public abstract S parseState(ExtconInfo extconInfo, String state);
+}