Package org.ka2ddo.yaac.util
Class CheckpointingLogger
java.lang.Object
java.io.OutputStream
org.ka2ddo.yaac.util.CheckpointingLogger
- All Implemented Interfaces:
Closeable
,Flushable
,AutoCloseable
This class defines a rolling logger that checkpoints the last N bytes of a log file
to a disk file.
- Author:
- Andrew Pavlin, KA2DDO
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Constructor Summary
ConstructorDescriptionCheckpointingLogger
(int bufSize, File logFile) Create a CheckpointingLogger stream with the specified maximum file size and path to the file. -
Method Summary
Modifier and TypeMethodDescriptionvoid
close()
Closes this output stream and releases any system resources associated with this stream.void
flush()
Flushes this output stream and forces any buffered output bytes to be written out.void
Really flush this output stream and forces any buffered output bytes to be written out.int
Get the last-written size of the log file.int
Get the current position in the buffer for the next character to write (may be end of buffer).Get the current contents of the logger's buffer.Report the pathname of the file where this logger will checkpoint the log data.int
Return the maximum number of bytes this logger can hold.void
write
(byte[] b, int off, int len) Writeslen
bytes from the specified byte array starting at offsetoff
to this output stream.void
write
(int b) Writes the specified byte to this output stream.Methods inherited from class java.io.OutputStream
nullOutputStream, write
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Constructor Details
-
CheckpointingLogger
Create a CheckpointingLogger stream with the specified maximum file size and path to the file.- Parameters:
bufSize
- int maximum file size in byteslogFile
- File pointing to where the data should be checkpointed
-
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Method Details
-
close
Closes this output stream and releases any system resources associated with this stream. The general contract ofclose
is that it closes the output stream. A closed stream cannot perform output operations and cannot be reopened.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Overrides:
close
in classOutputStream
- Throws:
IOException
- if an I/O error occurs.
-
write
Writeslen
bytes from the specified byte array starting at offsetoff
to this output stream. The general contract forwrite(b, off, len)
is that some of the bytes in the arrayb
are written to the output stream in order; elementb[off]
is the first byte written andb[off+len-1]
is the last byte written by this operation.If
b
isnull
, aNullPointerException
is thrown.If
off
is negative, orlen
is negative, oroff+len
is greater than the length of the arrayb
, then anIndexOutOfBoundsException
is thrown.- Overrides:
write
in classOutputStream
- Parameters:
b
- the data.off
- the start offset in the data.len
- the number of bytes to write.- Throws:
IOException
- if an I/O error occurs. In particular, anIOException
is thrown if the output stream is closed.
-
write
Writes the specified byte to this output stream. The general contract forwrite
is that one byte is written to the output stream. The byte to be written is the eight low-order bits of the argumentb
. The 24 high-order bits ofb
are ignored.- Specified by:
write
in classOutputStream
- Parameters:
b
- thebyte
.- Throws:
IOException
- if an I/O error occurs. In particular, anIOException
may be thrown if the output stream has been closed.
-
flush
public void flush()Flushes this output stream and forces any buffered output bytes to be written out. The general contract offlush
is that calling it is an indication that, if any bytes previously written have been buffered by the implementation of the output stream, such bytes should immediately be written to their intended destination.If the intended destination of this stream is an abstraction provided by the underlying operating system, for example a file, then flushing the stream guarantees only that bytes previously written to the stream are passed to the operating system for writing; it does not guarantee that they are actually written to a physical device such as a disk drive.
- Specified by:
flush
in interfaceFlushable
- Overrides:
flush
in classOutputStream
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flushImpl
Really flush this output stream and forces any buffered output bytes to be written out.- Throws:
IOException
- if an I/O error occurs.
-
getLogPathName
Report the pathname of the file where this logger will checkpoint the log data.- Returns:
- absolute pathname of log file
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getLoggerContents
Get the current contents of the logger's buffer.- Returns:
- the String contents of the log buffer
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getFileLength
public int getFileLength()Get the last-written size of the log file.- Returns:
- file size in bytes
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getLength
public int getLength()Get the current position in the buffer for the next character to write (may be end of buffer).- Returns:
- current length of buffer contents
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getMaxSize
public int getMaxSize()Return the maximum number of bytes this logger can hold.- Returns:
- byte size of logger's buffer
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