简单使用

简单使用

1. 用打的日志(或方法打的日志),可以用logcat -b events查看

    frameworks/base/core/java/android/util/
        //tag:The event type tag code. value:value to log 
        public static native int writeEvent(int tag, var value);
        public static native void readEvents(int[] tags, Collection<Event> output);
        //从system/etc/event-log-tags读后同时放到了sTagCodes,sTagNames两个map中
        private static final String TAGS_FILE = "/system/etc/event-log-tags"; 
        private static HashMap<String, Integer> sTagCodes = null; 
        private static HashMap<Integer, String> sTagNames = null;

2. 很多模块有该文件, writeEvent()参数tag value也是在其中被声明的

    packages/providers/BlacklistProvider/src/com/android/providers/black/
    packages/providers/CalendarProvider/src/com/android/providers/calendar/
    packages/providers/ContactsProvider/src/com/android/providers/contacts/
    packages/services/Telephony/src/com/android/phone/
    packages/apps/Settings/src/com/android/settings/
    packages/apps/QuickSearchBox/src/com/android/quicksearchbox/
    frameworks/base/services/core/java/com/android/server/
    frameworks/base/services/core/java/com/android/server/am/
    frameworks/base/packages/SystemUI/src/com/android/systemui/

3. 在中配置

    logcat中LOCAL_SRC_FILES:=  
    systemui中LOCAL_SRC_FILES := src/com/android/systemui/

4. 文件格式说明

   每一行大致三部分组成: Tag numbers + Tag names + (<名字>|数据类型[|数据单位]),(<名字>|数据类型[|数据单位])
   logcat打印内容就是第二部分+第三部分
   详见:android/system/core/logcat/

5. 编译时被翻译成了java

    frameworks/base/core/java/com/android/internal/logging/
    
        option java_package ;
        524287 sysui_view_visibility (category|1|5),(visible|1|6)
        524288 sysui_action (category|1|5),(pkg|3)
        524290 sysui_count (name|3),(increment|1)
        524291 sysui_histogram (name|3),(bucket|1)
    
    out/target/common/obj/JAVA_LIBRARIES/framework_intermediates/src/.../logging/
    
        public class EventLogTags {
          private EventLogTags() { }  // don't instantiate
        
          /** 524287 sysui_view_visibility (category|1|5),(visible|1|6) */
          public static final int SYSUI_VIEW_VISIBILITY = 524287;
        
          /** 524288 sysui_action (category|1|5),(pkg|3) */
          public static final int SYSUI_ACTION = 524288;
        
          /** 524290 sysui_count (name|3),(increment|1) */
          public static final int SYSUI_COUNT = 524290;
        
          /** 524291 sysui_histogram (name|3),(bucket|1) */
          public static final int SYSUI_HISTOGRAM = 524291;
        
          public static void writeSysuiViewVisibility(int category, int visible) {
            (SYSUI_VIEW_VISIBILITY, category, visible);
          }
        
          public static void writeSysuiAction(int category, String pkg) {
            (SYSUI_ACTION, category, pkg);
          }
        
          public static void writeSysuiCount(String name, int increment) {
            (SYSUI_COUNT, name, increment);
          }
        
          public static void writeSysuiHistogram(String name, int bucket) {
            (SYSUI_HISTOGRAM, name, bucket);
          }
        }

6. 相关脚本

    android/build/tools 目录下有三个event_log相关的脚本  
        event_log_tags.py //读取跟解析event_log_tags文件
         //把文件翻成java
         //把多个合并成一个,并检查number冲突
    
    使用及/system/etc/event-log-tags文件创建时间点  
        详见:android/build/core/Makefile -- .PHONY: event-log-tags
    
    遗留:event-log-tags被使用细节?其他两个py被使用时间点?