Fix Android sink.

1. Remove lock.
2. Improve error detection.
3. Remove unsupported log levels.

include/spdlog/sinks/android_sink.h

@@ -7,51 +7,42 @@
 
 #if defined(__ANDROID__)
 
-#include <spdlog/sinks/base_sink.h>
-#include <spdlog/details/null_mutex.h>
-
-#include <android/log.h>
+#include <spdlog/sinks/sink.h>
 
 #include <mutex>
 #include <string>
+#include <android/log.h>
 
 namespace spdlog
 {
 namespace sinks
 {
+
 /*
 * Android sink (logging using __android_log_write)
+* __android_log_write is thread-safe. No lock is needed.
 */
-template<class Mutex>
-class base_android_sink : public base_sink < Mutex >
+class android_sink : public sink
 {
 public:
-    explicit base_android_sink(std::string tag="spdlog"): _tag(tag)
-    {
-    }
+    explicit android_sink(const std::string& tag = "spdlog"): _tag(tag) {}
 
-    void flush() override
-    {
-    }
-
-protected:
-    void _sink_it(const details::log_msg& msg) override
+    void log(const details::log_msg& msg) override
     {
         const android_LogPriority priority = convert_to_android(msg.level);
-        const int expected_size = msg.formatted.size();
-        const int size = __android_log_write(
+        // See system/core/liblog/logger_write.c for explanation of return value
+        const int ret = __android_log_write(
                              priority, _tag.c_str(), msg.formatted.c_str()
                          );
-        if (size > expected_size)
-        {
-            // Will write a little bit more than original message
-        }
-        else
-        {
-            throw spdlog_ex("Send to Android logcat failed");
+        if (ret < 0) {
+          throw spdlog_ex("__android_log_write() failed", ret);
         }
     }
 
+    void flush() override
+    {
+    }
+
 private:
     static android_LogPriority convert_to_android(spdlog::level::level_enum level)
     {
@@ -63,29 +54,20 @@ private:
             return ANDROID_LOG_DEBUG;
         case spdlog::level::info:
             return ANDROID_LOG_INFO;
-        case spdlog::level::notice:
-            return ANDROID_LOG_INFO;
         case spdlog::level::warn:
             return ANDROID_LOG_WARN;
         case spdlog::level::err:
             return ANDROID_LOG_ERROR;
         case spdlog::level::critical:
             return ANDROID_LOG_FATAL;
-        case spdlog::level::alert:
-            return ANDROID_LOG_FATAL;
-        case spdlog::level::emerg:
-            return ANDROID_LOG_FATAL;
         default:
-            throw spdlog_ex("Incorrect level value");
+            return ANDROID_LOG_DEFAULT;
         }
     }
 
     std::string _tag;
 };
 
-typedef base_android_sink<std::mutex> android_sink_mt;
-typedef base_android_sink<details::null_mutex> android_sink_st;
-
 }
 }