Add ProcessInfoService to activity manager.

- Adds a new AIDL interface for querying process
  information from activity manager.

Bug: 19186859

Change-Id: Ic08858f346d6b66e7bfc9da6faa2c6e38d9b2e82
diff --git a/libs/binder/ProcessInfoService.cpp b/libs/binder/ProcessInfoService.cpp
new file mode 100644
index 0000000..fb28643
--- /dev/null
+++ b/libs/binder/ProcessInfoService.cpp
@@ -0,0 +1,70 @@
+/*
+ * Copyright 2015 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.
+ */
+
+#include <binder/ProcessInfoService.h>
+#include <binder/IServiceManager.h>
+
+#include <utils/Log.h>
+#include <utils/String16.h>
+
+namespace android {
+
+ProcessInfoService::ProcessInfoService() {
+    updateBinderLocked();
+}
+
+status_t ProcessInfoService::getProcessStatesImpl(size_t length, /*in*/ int32_t* pids,
+        /*out*/ int32_t* states) {
+    status_t err = NO_ERROR;
+    sp<IProcessInfoService> pis;
+    mProcessInfoLock.lock();
+    pis = mProcessInfoService;
+    mProcessInfoLock.unlock();
+
+    for (int i = 0; i < BINDER_ATTEMPT_LIMIT; i++) {
+
+        if (pis != NULL) {
+            err = pis->getProcessStatesFromPids(length, /*in*/ pids, /*out*/ states);
+            if (err == NO_ERROR) return NO_ERROR; // success
+            if (IInterface::asBinder(pis)->isBinderAlive()) return err;
+        }
+        sleep(1);
+
+        mProcessInfoLock.lock();
+        if (pis == mProcessInfoService) {
+            updateBinderLocked();
+        }
+        pis = mProcessInfoService;
+        mProcessInfoLock.unlock();
+    }
+
+    ALOGW("%s: Could not retrieve process states from ProcessInfoService after %d retries.",
+            __FUNCTION__, BINDER_ATTEMPT_LIMIT);
+
+    return TIMED_OUT;
+}
+
+void ProcessInfoService::updateBinderLocked() {
+    const sp<IServiceManager> sm(defaultServiceManager());
+    if (sm != NULL) {
+        const String16 name("processinfo");
+        mProcessInfoService = interface_cast<IProcessInfoService>(sm->checkService(name));
+    }
+}
+
+ANDROID_SINGLETON_STATIC_INSTANCE(ProcessInfoService);
+
+}; // namespace android