public void freeSegment(LayerWriteGroup tx, FreespaceExtent segment_extent) { // (1) add the segment to the pending list (pending free) if (tx.type != LayerWriteGroup.WriteGroupType.DISK_ATOMIC_FLUSH) { throw new Exception("freeSegment() requires DISK_ATOMIC write group"); } // NOTE: DISK_ATOMIC writes are not seen in the memory segment until the atomic write group applies // so these changes will not be seen until then RecordKey key = new RecordKey().appendParsedKey(".ROOT/FREELIST/PENDING") .appendKeyPart(new RecordKeyType_Long(segment_extent.end_addr)); RecordUpdate payload = RecordUpdate.WithPayload(segment_extent.pack()); tx.setValue(key, payload); // (2) add a handler to get notified when the block is no longer referenced, so it can // be moved from pending to actually free. LayerWriteGroup fwg = this.store.newWriteGroup(LayerWriteGroup.WriteGroupType.DISK_ATOMIC_NOFLUSH); // we don't want to ask for the notification until the write-group freeing this segment is finished tx.addCompletion(delegate() { tx.mylayer.regionmgr.notifyRegionSafeToFree(segment_extent.start_addr, delegate(long addr) { this.handleRegionSafeToFree(addr, segment_extent, fwg); }); }); }