Add a DropboxWriter in statsd.

+ The DropboxWriter keeps data in cache, and flush to files once the
  size exceeds the maximum value.

+ Different components should create their owner DropboxWriter with
  different tags, e.g., anomly detection, experiment metrics, etc.

+ Copied stats_log related protos from g3

Test: run statsd, and adb shell dumpsys dropbox
      Will add unit tests.

Change-Id: If06e9a9953be32082252b340a97124d732656b40
diff --git a/cmds/statsd/src/StatsLogProcessor.cpp b/cmds/statsd/src/StatsLogProcessor.cpp
new file mode 100644
index 0000000..f49dfde
--- /dev/null
+++ b/cmds/statsd/src/StatsLogProcessor.cpp
@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2017 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 <StatsLogProcessor.h>
+
+#include <log/event_tag_map.h>
+#include <log/logprint.h>
+#include <utils/Errors.h>
+
+#include <frameworks/base/cmds/statsd/src/stats_log.pb.h>
+
+using namespace android;
+using android::os::statsd::StatsLogEntry;
+
+StatsLogProcessor::StatsLogProcessor() : m_dropbox_writer("all-logs")
+{
+    // Initialize the EventTagMap, which is how we know the names of the numeric event tags.
+    // If this fails, we can't print well, but something will print.
+    m_tags = android_openEventTagMap(NULL);
+
+    // Printing format
+    m_format = android_log_format_new();
+    android_log_setPrintFormat(m_format, FORMAT_THREADTIME);
+}
+
+StatsLogProcessor::~StatsLogProcessor()
+{
+    if (m_tags != NULL) {
+        android_closeEventTagMap(m_tags);
+    }
+    android_log_format_free(m_format);
+}
+
+void
+StatsLogProcessor::OnLogEvent(const log_msg& msg)
+{
+    status_t err;
+    AndroidLogEntry entry;
+    char buf[1024];
+
+    err = android_log_processBinaryLogBuffer(&(const_cast<log_msg*>(&msg)->entry_v1),
+                &entry, m_tags, buf, sizeof(buf));
+
+    // dump all statsd logs to dropbox for now.
+    // TODO: Add filtering, aggregation, etc.
+    if (err == NO_ERROR) {
+        StatsLogEntry logEntry;
+        logEntry.set_uid(entry.uid);
+        logEntry.set_pid(entry.pid);
+        logEntry.set_start_report_millis(entry.tv_sec / 1000 + entry.tv_nsec / 1000 / 1000);
+        logEntry.add_pairs()->set_value_str(entry.message, entry.messageLen);
+        m_dropbox_writer.addEntry(logEntry);
+    }
+}
+