void putBuffer(DataBuffer buffer, BufferNode node) throws IOException {
		if (activeFile == null) {
			throw new AssertException("Snapshot not in progress");
		}
		if (newSnapshot || !node.snapshotTaken[snapshotIndex]) {
			activeFile.putBuffer(buffer);
			node.snapshotTaken[snapshotIndex] = true;
			++buffersSaved[snapshotIndex];
		}
		else {
			++buffersIgnored[snapshotIndex];
		}
		oldIndexSet.remove(node.id);
	}
Write a modified buffer corresponding to the specified BufferNode
to the current open snapshot file.  The following BufferNode fields
are utilized which should not be modified concurrent with this
method invocation: 'id' and  'snapshotTaken'.
@param buf
@param node
@throws IOException
Ghidra/Framework/DB/src/main/java/db/buffers/RecoveryMgr.java