func write(fp io.WriterAt,
c *cache.CacheMap,
devid, offset, blocks uint32,
buffer []byte) {
here := make(chan *message.Message, blocks)
cacheoffset := cache.Address64(cache.Address{Devid: devid, Block: offset})
// Send invalidates for each block
iopkt := &message.IoPkt{
Address: cacheoffset,
Blocks: blocks,
}
c.Invalidate(iopkt)
// Write to storage back end
// :TODO: check return status
fp.WriteAt(buffer, int64(offset)*4*KB)
// Now write to cache
msg := message.NewMsgPut()
msg.RetChan = here
iopkt = msg.IoPkt()
iopkt.Blocks = blocks
iopkt.Address = cacheoffset
iopkt.Buffer = buffer
c.Put(msg)
<-here
}
func readandstore(fp io.ReaderAt,
c *cache.CacheMap,
devid, offset, blocks uint32,
buffer []byte,
retchan chan *message.Message) {
fp.ReadAt(buffer, int64(offset)*4*KB)
m := message.NewMsgPut()
m.RetChan = retchan
io := m.IoPkt()
io.Address = cache.Address64(cache.Address{Devid: devid, Block: offset})
io.Buffer = buffer
io.Blocks = blocks
c.Put(m)
}
func read(fp io.ReaderAt,
c *cache.CacheMap,
devid, offset, blocks uint32,
buffer []byte) {
godbc.Require(len(buffer)%(4*KB) == 0)
here := make(chan *message.Message, blocks)
cacheoffset := cache.Address64(cache.Address{Devid: devid, Block: offset})
msg := message.NewMsgGet()
msg.RetChan = here
iopkt := msg.IoPkt()
iopkt.Buffer = buffer
iopkt.Address = cacheoffset
iopkt.Blocks = blocks
msgs := 0
hitpkt, err := c.Get(msg)
if err != nil {
//fmt.Printf("|blocks:%d::hits:0--", blocks)
// None found
// Read the whole thing from backend
fp.ReadAt(buffer, int64(offset)*4*KB)
m := message.NewMsgPut()
m.RetChan = here
io := m.IoPkt()
io.Address = cacheoffset
io.Buffer = buffer
io.Blocks = blocks
c.Put(m)
msgs++
} else if hitpkt.Hits != blocks {
//fmt.Printf("|******blocks:%d::hits:%d--", blocks, hitpkt.Hits)
// Read from storage the ones that did not have
// in the hit map.
var be_offset, be_block, be_blocks uint32
var be_read_ready = false
for block := uint32(0); block < blocks; block++ {
if !hitpkt.Hitmap[int(block)] {
if be_read_ready {
be_blocks++
} else {
be_read_ready = true
be_offset = offset + block
be_block = block
be_blocks++
}
} else {
if be_read_ready {
// Send read
msgs++
go readandstore(fp, c, devid,
be_offset,
be_blocks,
cache.SubBlockBuffer(buffer, 4*KB, be_block, be_blocks),
here)
be_read_ready = false
be_blocks = 0
be_offset = 0
be_block = 0
}
}
}
if be_read_ready {
msgs++
go readandstore(fp, c, devid,
be_offset,
be_blocks,
cache.SubBlockBuffer(buffer, 4*KB, be_block, be_blocks),
here)
}
} else {
msgs = 1
}
// Wait for blocks to be returned
for msg := range here {
msgs--
godbc.Check(msg.Err == nil, msg)
godbc.Check(msgs >= 0, msgs)
if msgs == 0 {
return
}
}
}
