fix: resource leak when JournalChannel is not fully initialized

[shoothzj]

Motivation

There is a resource leak in the JournalChannel implementation of Apache Bookkeeper when the channel is closed before it is fully initialized (specifically, before the writing of headers begins). In such cases, the buffer channel (bc) is not yet instantiated, but the file channel (fc) might already be open.

Changes

Updated the close() method in JournalChannel to include a conditional check that closes the file channel (fc) if the buffer channel (bc) is null. This ensures that all resources are properly released, even if the JournalChannel is prematurely closed before full initialization.

wrie header method

bookkeeper/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/JournalChannel.java

Lines 250 to 265 in ba7f988

	private void writeHeader(Journal.BufferedChannelBuilder bcBuilder,
	int writeBufferSize) throws IOException {
	int headerSize = (V4 == formatVersion) ? VERSION_HEADER_SIZE : HEADER_SIZE;
	ByteBuffer bb = ByteBuffer.allocate(headerSize);
	ZeroBuffer.put(bb);
	bb.clear();
	bb.put(magicWord);
	bb.putInt(formatVersion);
	bb.clear();
	fc.write(bb);
	bc = bcBuilder.create(fc, writeBufferSize);
	forceWrite(true);
	nextPrealloc = this.preAllocSize;
	fc.write(zeros, nextPrealloc - journalAlignSize);
	}

[shoothzj]

@dlg99 @eolivelli @hangc0276 @merlimat @nicoloboschi @StevenLuMT @wenbingshen @zhaijack PTAL

[eolivelli]

LGTM