func (s *MySuite) TestPage(c *C) {
b := new(Block)
page := NewPage(b)
c.Check(page.IsNew(), Equals, true)
page.Init(0)
c.Check(page.IsValid(), Equals, true)
c.Check(page.IsEmpty(), Equals, true)
c.Check(page.PageSize(), Equals, uint16(system.BlockSize))
c.Check(page.PageLayourVersion(), Equals, uint16(4))
page.SetLower(128)
page.SetUpper(1024)
c.Check(page.Lower(), Equals, uint16(128))
c.Check(page.Upper(), Equals, uint16(1024))
c.Check(page.IsEmpty(), Equals, false)
c.Check(page.IsNew(), Equals, false)
fout, _ := os.Create("/tmp/foo")
fout.Write(b[:])
fout.Close()
fin, _ := os.Open("/tmp/foo")
b2 := new(Block)
fin.Read(b2[:])
fin.Close()
page2 := NewPage(b2)
c.Check(page2.PageSize(), Equals, uint16(system.BlockSize))
c.Check(page2.PageLayourVersion(), Equals, uint16(4))
c.Check(page2.Lower(), Equals, uint16(128))
c.Check(page2.Upper(), Equals, uint16(1024))
// Test for Add/Item
// TODO: overwrite case
page3 := NewPage(new(Block))
page3.Init(0)
item1 := make([]byte, 128)
item1[0] = 0xbe
item1[1] = 0xde
item2 := make([]byte, 256)
item2[254] = 0xaa
item2[255] = 0xab
offset1 := page3.AddItem(item1, system.InvalidOffsetNumber, false, true)
offset2 := page3.AddItem(item2, system.InvalidOffsetNumber, false, true)
c.Check(offset1, Equals, system.OffsetNumber(1))
c.Check(offset2, Equals, system.OffsetNumber(2))
itemId1 := page3.ItemId(offset1)
item1 = page3.Item(itemId1)
c.Check(item1[0], Equals, byte(0xbe))
c.Check(item1[1], Equals, byte(0xde))
itemId2 := page3.ItemId(offset2)
item2 = page3.Item(itemId2)
c.Check(item2[254], Equals, byte(0xaa))
c.Check(item2[255], Equals, byte(0xab))
}
// Returns the maximum offset number used by the given page.
// Since offset numbers are 1-based, this is also the number
// of items on the page. If the page is not initialized (pd_lower == 0),
// we must return zero to ensure sane behavior.
func (page *Page) MaxOffsetNumber() system.OffsetNumber {
lower := int16(page.Lower())
offbytes := lower - int16(sizeOfPageHeader)
if offbytes <= 0 {
return 0
} else {
itemid_size := unsafe.Sizeof(ItemId(0))
return system.OffsetNumber(uint16(offbytes) / uint16(itemid_size))
}
}