Support atoms subscription via shell cmd.

+ This feature is for supporting perfd.
+ Perfd is built outside android and doesnot depend on any android libraries.
  So the communication between perfd and statsd can only be via non-android IPCs
  (such as socket, pipe, file descriptors etc.)
+ Perfd runs as a shell user, so using the existing shell cmd is a natural choice.
+ The input is a simple config, and output is a stream of atoms proto binary data.

+ Also cleaned up the code so that we use file descriptor directly instead of creating another
  FILE*.

TODO: pulled atom subscription.

Bug: 110536553
Test: statsd_test and manually tested
Change-Id: I64b0061cc66b5f7648147885a2ac1af531c19917

1 files changed, 140 insertions, 0 deletions

diff --git a/cmds/statsd/src/shell/ShellSubscriber.cpp b/cmds/statsd/src/shell/ShellSubscriber.cpp
new file mode 100644
index 000000000000..3cd49d722fea
--- /dev/null
+++ b/cmds/statsd/src/shell/ShellSubscriber.cpp
@@ -0,0 +1,140 @@
+/*
+ * 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.
+ */
+#define DEBUG true  // STOPSHIP if true
+#include "Log.h"
+
+#include "ShellSubscriber.h"
+
+#include "matchers/matcher_util.h"
+
+#include <android-base/file.h>
+
+using android::util::ProtoOutputStream;
+
+namespace android {
+namespace os {
+namespace statsd {
+
+void ShellSubscriber::startNewSubscription(int in, int out, sp<IResultReceiver> resultReceiver) {
+    VLOG("start new shell subscription");
+    {
+        std::lock_guard<std::mutex> lock(mMutex);
+        if (mResultReceiver != nullptr) {
+            VLOG("Only one shell subscriber is allowed.");
+            return;
+        }
+        mInput = in;
+        mOutput = out;
+        mResultReceiver = resultReceiver;
+        IInterface::asBinder(mResultReceiver)->linkToDeath(this);
+    }
+
+    // Spawn another thread to read the config updates from the input file descriptor
+    std::thread reader([in, this] { readConfig(in); });
+    reader.detach();
+
+    std::unique_lock<std::mutex> lk(mMutex);
+
+    mShellDied.wait(lk, [this, resultReceiver] { return mResultReceiver != resultReceiver; });
+    if (reader.joinable()) {
+        reader.join();
+    }
+}
+
+void ShellSubscriber::updateConfig(const ShellSubscription& config) {
+    std::lock_guard<std::mutex> lock(mMutex);
+    mPushedMatchers.clear();
+    for (const auto& pushed : config.pushed()) {
+        mPushedMatchers.push_back(pushed);
+        VLOG("adding matcher for atom %d", pushed.atom_id());
+    }
+}
+
+void ShellSubscriber::readConfig(int in) {
+    if (in <= 0) {
+        return;
+    }
+
+    while (1) {
+        size_t bufferSize = 0;
+        int result = 0;
+        if ((result = read(in, &bufferSize, sizeof(bufferSize))) == 0) {
+            VLOG("Done reading");
+            break;
+        } else if (result < 0 || result != sizeof(bufferSize)) {
+            ALOGE("Error reading config size");
+            break;
+        }
+
+        vector<uint8_t> buffer(bufferSize);
+        if ((result = read(in, buffer.data(), bufferSize)) > 0 && ((size_t)result) == bufferSize) {
+            ShellSubscription config;
+            if (config.ParseFromArray(buffer.data(), bufferSize)) {
+                updateConfig(config);
+            } else {
+                ALOGE("error parsing the config");
+                break;
+            }
+        } else {
+            VLOG("Error reading the config, returned: %d, expecting %zu", result, bufferSize);
+            break;
+        }
+    }
+}
+
+void ShellSubscriber::cleanUpLocked() {
+    // The file descriptors will be closed by binder.
+    mInput = 0;
+    mOutput = 0;
+    mResultReceiver = nullptr;
+    mPushedMatchers.clear();
+    VLOG("done clean up");
+}
+
+void ShellSubscriber::onLogEvent(const LogEvent& event) {
+    std::lock_guard<std::mutex> lock(mMutex);
+
+    if (mOutput <= 0) {
+        return;
+    }
+
+    for (const auto& matcher : mPushedMatchers) {
+        if (matchesSimple(*mUidMap, matcher, event)) {
+            // First write the payload size.
+            size_t bufferSize = mProto.size();
+            write(mOutput, &bufferSize, sizeof(bufferSize));
+
+            // Then write the payload.
+            event.ToProto(mProto);
+            mProto.flush(mOutput);
+            mProto.clear();
+            break;
+        }
+    }
+}
+
+void ShellSubscriber::binderDied(const wp<IBinder>& who) {
+    {
+        VLOG("Shell exits");
+        std::lock_guard<std::mutex> lock(mMutex);
+        cleanUpLocked();
+    }
+    mShellDied.notify_all();
+}
+
+}  // namespace statsd
+}  // namespace os
+}  // namespace android
\ No newline at end of file