refactor logging. Details:

- packages use tagged logger sending log messages to shared (process-wide) logging engine
- log writers (interface ethlog.LogSystem) can be added to the logging engine by wrappers/guis/clients
- shared logging engine dispatching to multiple log systems
- log level can be set separately per log system
- async logging thread: logging IO does not block main thread
- log messages are synchronously stringified to avoid incorrectly logging of changed states
- README.md
- loggers_test

1 files changed, 58 insertions, 0 deletions

diff --git a/ethlog/README.md b/ethlog/README.md
new file mode 100644
index 000000000..f8818d98e
--- /dev/null
+++ b/ethlog/README.md
@@ -0,0 +1,58 @@
+## Features
+
+- packages use tagged logger sending log messages to shared (process-wide) logging engine
+- log writers (interface ethlog.LogSystem) can be added to the logging engine by wrappers/guis/clients
+- shared logging engine dispatching to multiple log systems
+- log level can be set separately per log system
+- async logging thread: logging IO does not block main thread 
+- log messages are synchronously stringified to avoid incorrectly logging of changed states 
+
+## Usage
+
+In an ethereum component package:
+
+    import "github.com/ethereum/eth-go/ethlog"
+
+    // package-wide logger using tag
+    var logger = ethlog.NewLogger("TAG")
+
+    logger.Infoln("this is info") # > [TAG] This is info
+
+Ethereum wrappers should register log systems conforming to ethlog.LogSystem
+
+    import "github.com/ethereum/eth-go/ethlog"
+    
+    type CustomLogWriter struct {
+      logLevel ethlog.LogLevel
+    }
+
+    func (t *TestLogSystem) SetLogLevel(i LogLevel) {
+      t.level = i
+    }
+
+    func (t *TestLogSystem) GetLogLevel() LogLevel {
+      return t.level
+    }
+
+    func (c *CustomLogWriter) Printf(format string, v...interface{}) {
+      //....
+    }
+
+    func (c *CustomLogWriter) Println(v...interface{}) {
+      //....
+    }
+
+    ethlog.AddLogWriter(&CustomLogWriter{})
+
+ethlog also provides constructors for that wrap io.Writers into a standard logger with a settable level:
+
+    filename := "test.log"
+    file, _ := os.OpenFile(filename, os.O_RDWR|os.O_CREATE, os.ModePerm)
+    fileLogSystem := NewStdLogSystem(file, 0, WarnLevel)
+    AddLogSystem(fileLogSystem)
+    stdOutLogSystem := NewStdLogSystem(os.Stdout, 0, WarnLevel)
+    AddLogSystem(stdOutLogSystem)
+
+
+
+