private ICachedPage findLeaf()

in hyracks/hyracks-storage-am-rtree/src/main/java/org/apache/hyracks/storage/am/rtree/impls/RTree.java [205:328]
101 lines of code
18 McCabe index (conditional complexity)

    private ICachedPage findLeaf(RTreeOpContext ctx) throws HyracksDataException {
        int pageId = rootPage;
        boolean writeLatched = false;
        boolean readLatched = false;
        boolean succeeded = false;
        ICachedPage node = null;
        boolean isLeaf = false;
        long pageLsn = 0, parentLsn = 0;

        try {

            while (true) {
                if (!writeLatched) {
                    node = bufferCache.pin(BufferedFileHandle.getDiskPageId(fileId, pageId), false);
                    ctx.interiorFrame.setPage(node);
                    isLeaf = ctx.interiorFrame.isLeaf();
                    if (isLeaf) {
                        node.acquireWriteLatch();
                        writeLatched = true;

                        if (!ctx.interiorFrame.isLeaf()) {
                            node.releaseWriteLatch(true);
                            writeLatched = false;
                            bufferCache.unpin(node);
                            continue;
                        }
                    } else {
                        // Be optimistic and grab read latch first. We will swap
                        // it to write latch if we need to enlarge the best
                        // child tuple.
                        node.acquireReadLatch();
                        readLatched = true;
                    }
                }

                if (pageId != rootPage && parentLsn < ctx.interiorFrame.getPageNsn()) {
                    // Concurrent split detected, go back to parent and
                    // re-choose the best child
                    if (writeLatched) {
                        node.releaseWriteLatch(true);
                        writeLatched = false;
                        bufferCache.unpin(node);
                    } else {
                        node.releaseReadLatch();
                        readLatched = false;
                        bufferCache.unpin(node);
                    }

                    pageId = ctx.pathList.getLastPageId();
                    if (pageId != rootPage) {
                        parentLsn = ctx.pathList.getPageLsn(ctx.pathList.size() - 2);
                    }
                    ctx.pathList.moveLast();
                    continue;
                }

                pageLsn = ctx.interiorFrame.getPageLsn();
                ctx.pathList.add(pageId, pageLsn, -1);

                if (!isLeaf) {
                    // findBestChild must be called *before* checkIfEnlarementIsNeeded
                    int childPageId = ctx.interiorFrame.findBestChild(ctx.getTuple(), ctx.cmp);
                    boolean enlarementIsNeeded = ctx.interiorFrame.checkIfEnlarementIsNeeded(ctx.getTuple(), ctx.cmp);

                    if (enlarementIsNeeded) {
                        if (!writeLatched) {
                            node.releaseReadLatch();
                            readLatched = false;
                            bufferCache.unpin(node);

                            node = bufferCache.pin(BufferedFileHandle.getDiskPageId(fileId, pageId), false);
                            node.acquireWriteLatch();
                            writeLatched = true;
                            ctx.interiorFrame.setPage(node);

                            if (ctx.interiorFrame.getPageLsn() != pageLsn) {
                                // The page was changed while we unlocked it;
                                // thus, retry (re-choose best child)

                                ctx.pathList.moveLast();
                                continue;
                            }
                        }
                        // We don't need to reset the frameTuple because it is
                        // already pointing to the best child
                        ctx.interiorFrame.enlarge(ctx.getTuple(), ctx.cmp);

                        node.releaseWriteLatch(true);
                        writeLatched = false;
                        bufferCache.unpin(node);
                    } else {
                        if (readLatched) {
                            node.releaseReadLatch();
                            readLatched = false;
                            bufferCache.unpin(node);
                        } else if (writeLatched) {
                            node.releaseWriteLatch(true);
                            writeLatched = false;
                            bufferCache.unpin(node);
                        }
                    }

                    pageId = childPageId;
                    parentLsn = pageLsn;
                } else {
                    ctx.leafFrame.setPage(node);
                    succeeded = true;
                    return node;
                }
            }
        } finally {
            if (!succeeded) {
                if (readLatched) {
                    node.releaseReadLatch();
                    readLatched = false;
                    bufferCache.unpin(node);
                } else if (writeLatched) {
                    node.releaseWriteLatch(true);
                    writeLatched = false;
                    bufferCache.unpin(node);
                }
            }
        }
    }