Method spill

bucket.go:746–802

spill writes all the nodes for this bucket to dirty pages.

()

// spill writes all the nodes for this bucket to dirty pages.
func (b *Bucket) spill() error {
	// Spill all child buckets first.
	for name, child := range b.buckets {
		// If the child bucket is small enough and it has no child buckets then
		// write it inline into the parent bucket's page. Otherwise spill it
		// like a normal bucket and make the parent value a pointer to the page.
		var value []byte
		if child.inlineable() {
			child.free()
			value = child.write()
		} else {
			if err := child.spill(); err != nil {
				return err
			}

			// Update the child bucket header in this bucket.
			value = make([]byte, unsafe.Sizeof(common.InBucket{}))
			var bucket = (*common.InBucket)(unsafe.Pointer(&value[0]))
			*bucket = *child.InBucket
		}

		// Skip writing the bucket if there are no materialized nodes.
		if child.rootNode == nil {
			continue
		}

		// Update parent node.
		var c = b.Cursor()
		k, _, flags := c.seek([]byte(name))
		if !bytes.Equal([]byte(name), k) {
			panic(fmt.Sprintf("misplaced bucket header: %x -> %x", []byte(name), k))
		}
		if flags&common.BucketLeafFlag == 0 {
			panic(fmt.Sprintf("unexpected bucket header flag: %x", flags))
		}
		c.node().put([]byte(name), []byte(name), value, 0, common.BucketLeafFlag)
	}

	// Ignore if there's not a materialized root node.
	if b.rootNode == nil {
		return nil
	}

	// Spill nodes.
	if err := b.rootNode.spill(); err != nil {
		return err
	}
	b.rootNode = b.rootNode.root()

	// Update the root node for this bucket.
	if b.rootNode.pgid >= b.tx.meta.Pgid() {
		panic(fmt.Sprintf("pgid (%d) above high water mark (%d)", b.rootNode.pgid, b.tx.meta.Pgid()))
	}
	b.SetRootPage(b.rootNode.pgid)

	return nil
}