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package downloader
import (
"math"
"math/big"
"sync"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
"gopkg.in/fatih/set.v0"
)
// queue represents hashes that are either need fetching or are being fetched
type queue struct {
hashPool *set.Set
fetchPool *set.Set
blockHashes *set.Set
mu sync.Mutex
fetching map[string]*chunk
blocks []*types.Block
}
func newqueue() *queue {
return &queue{
hashPool: set.New(),
fetchPool: set.New(),
blockHashes: set.New(),
fetching: make(map[string]*chunk),
}
}
func (c *queue) reset() {
c.mu.Lock()
defer c.mu.Unlock()
c.hashPool.Clear()
c.fetchPool.Clear()
c.blockHashes.Clear()
c.blocks = nil
c.fetching = make(map[string]*chunk)
}
// reserve a `max` set of hashes for `p` peer.
func (c *queue) get(p *peer, max int) *chunk {
c.mu.Lock()
defer c.mu.Unlock()
// return nothing if the pool has been depleted
if c.hashPool.Size() == 0 {
return nil
}
limit := int(math.Min(float64(max), float64(c.hashPool.Size())))
// Create a new set of hashes
hashes, i := set.New(), 0
c.hashPool.Each(func(v interface{}) bool {
// break on limit
if i == limit {
return false
}
// skip any hashes that have previously been requested from the peer
if p.ignored.Has(v) {
return true
}
hashes.Add(v)
i++
return true
})
// if no hashes can be requested return a nil chunk
if hashes.Size() == 0 {
return nil
}
// remove the fetchable hashes from hash pool
c.hashPool.Separate(hashes)
c.fetchPool.Merge(hashes)
// Create a new chunk for the seperated hashes. The time is being used
// to reset the chunk (timeout)
chunk := &chunk{p, hashes, time.Now()}
// register as 'fetching' state
c.fetching[p.id] = chunk
// create new chunk for peer
return chunk
}
func (c *queue) has(hash common.Hash) bool {
return c.hashPool.Has(hash) || c.fetchPool.Has(hash)
}
func (c *queue) addBlock(id string, block *types.Block, td *big.Int) {
c.mu.Lock()
defer c.mu.Unlock()
// when adding a block make sure it doesn't already exist
if !c.blockHashes.Has(block.Hash()) {
c.hashPool.Remove(block.Hash())
c.blocks = append(c.blocks, block)
}
}
// deliver delivers a chunk to the queue that was requested of the peer
func (c *queue) deliver(id string, blocks []*types.Block) {
c.mu.Lock()
defer c.mu.Unlock()
chunk := c.fetching[id]
// If the chunk was never requested simply ignore it
if chunk != nil {
delete(c.fetching, id)
// check the length of the returned blocks. If the length of blocks is 0
// we'll assume the peer doesn't know about the chain.
if len(blocks) == 0 {
// So we can ignore the blocks we didn't know about
chunk.peer.ignored.Merge(chunk.hashes)
}
// seperate the blocks and the hashes
blockHashes := chunk.fetchedHashes(blocks)
// merge block hashes
c.blockHashes.Merge(blockHashes)
// Add the blocks
c.blocks = append(c.blocks, blocks...)
// Add back whatever couldn't be delivered
c.hashPool.Merge(chunk.hashes)
c.fetchPool.Separate(chunk.hashes)
}
}
// puts puts sets of hashes on to the queue for fetching
func (c *queue) put(hashes *set.Set) {
c.mu.Lock()
defer c.mu.Unlock()
c.hashPool.Merge(hashes)
}
type chunk struct {
peer *peer
hashes *set.Set
itime time.Time
}
func (ch *chunk) fetchedHashes(blocks []*types.Block) *set.Set {
fhashes := set.New()
for _, block := range blocks {
fhashes.Add(block.Hash())
}
ch.hashes.Separate(fhashes)
return fhashes
}
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