net.sergeych.tools

Class BufferedLogger

java.lang.Object

net.sergeych.tools.BufferedLogger

All Implemented Interfaces:

java.lang.AutoCloseable

public class BufferedLogger
extends java.lang.Object
implements java.lang.AutoCloseable

Navigable fast asynchronous buffered logger, thread safe. It's main features are:

- it does not block caller on log(String) using daemon thread to queue all logging requests

- it holds lasst records in memory from where it could be easily obtained using slice(long, int), getLast(int) and getCopy() calls.

It is possible to connect a logger to a PrintStream using printTo(PrintStream, boolean).

It is also possible to capture the whole stdout with interceptStdOut()

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	BufferedLogger.Entry Log entry structure provides ID to navigate, creation instant and the message.

Constructor Summary

Constructors

Constructor and Description
BufferedLogger(int maxEntries) Create buffered logger capable to hold in mempry up to specified number of entries, the excessive records will be purged automatically.

Method Summary

Modifier and Type	Method and Description
void	clear() clear the whole stored content.
void	close()
@NonNull BufferedLogger.Entry	d(java.lang.String message)
void	e(java.lang.String s)
protected void	finalize()
void	flush() Wait until all queued logging operation are finished.
boolean	flush(long millis) Wait for log messages queue emptied up to specified number of milliseconds
java.util.List<BufferedLogger.Entry>	getCopy() Get a copy af all currently stored entries
@NonNull java.util.List<BufferedLogger.Entry>	getLast(int maxEntries) Return most recent record up to specified number of entries.
void	interceptStdOut() Start intercepting stdout and log it to the buffer on the fly.
@NonNull BufferedLogger.Entry	log(java.lang.String message) Add log entry to the buffer.
java.io.PrintStream	printTo(java.io.PrintStream ps, boolean printTimestamp) Copy results to a given PrintStream (to be used with System.out, for example)
java.util.List<BufferedLogger.Entry>	slice(long id, int maxEntries) Get slice of entries based on the id.
void	stopInterceptingStdOut()

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BufferedLogger

public BufferedLogger(int maxEntries)

Create buffered logger capable to hold in mempry up to specified number of entries, the excessive records will be purged automatically.

Parameters:

maxEntries -

Method Detail

e

public void e(java.lang.String s)

flush

public void flush()
           throws java.lang.InterruptedException

Wait until all queued logging operation are finished. See log(String) fro details.

Throws:

java.lang.InterruptedException

flush

public boolean flush(long millis)

Wait for log messages queue emptied up to specified number of milliseconds

Parameters:

millis - to stop waiting after

Returns:

true if the messages queue is emptied, false if timeout is expired

printTo

public java.io.PrintStream printTo(java.io.PrintStream ps,
                                   boolean printTimestamp)

Copy results to a given PrintStream (to be used with System.out, for example)

Parameters:

ps - printStream to print to. Use null to cancel.

printTimestamp - true to add ISO timestamp to each line (like 2017-09-15T14:52:25.287Z)

Returns:

null or previously associated PrintStream

log

public @NonNull BufferedLogger.Entry log(java.lang.String message)

Add log entry to the buffer.

Parameters:

message -

Returns:

entry created for the log message

d

public @NonNull BufferedLogger.Entry d(java.lang.String message)

getLast

public @NonNull java.util.List<BufferedLogger.Entry> getLast(int maxEntries)

Return most recent record up to specified number of entries.

Parameters:

maxEntries - must be > 0. If current number of records is less than specified, returns all.

Returns:

List

slice

public java.util.List<BufferedLogger.Entry> slice(long id,
                                                  int maxEntries)

Get slice of entries based on the id. If maxEntries is positive, returns entries newest than a given id, otherwise oldest ones. The actual number if such records can be less than absolute value of maxEntries, so check the returned List size.

Parameters:

id - of the record to start with

maxEntries - and the direction, positive means newest than id (entry.id > id), negative for older (entry.id < id).

Returns:

possibly empty list of entries matching the criteria.

clear

public void clear()

clear the whole stored content.

getCopy

public java.util.List<BufferedLogger.Entry> getCopy()

Get a copy af all currently stored entries

Returns:

list of entries sorted by id

interceptStdOut

public void interceptStdOut()

Start intercepting stdout and log it to the buffer on the fly. Intercepted data will be also printed to the System.out. Use stopInterceptingStdOut() to cancel copying to log.

close

public void close()
           throws java.lang.Exception

Specified by:

close in interface java.lang.AutoCloseable

Throws:

java.lang.Exception

stopInterceptingStdOut

public void stopInterceptingStdOut()

finalize

protected void finalize()
                 throws java.lang.Throwable

Overrides:

finalize in class java.lang.Object

Throws:

java.lang.Throwable