Raise the nominal max requests for connections that download lots of useful chunks

Massive speed increases for some connections.

diff --git a/connection.go b/connection.go
index 20a4f90164209c867e82f62edc0678a75be7e01b..bf06a975ca5604558bec8c0a132a2fc4ce765521 100644 (file)
--- a/connection.go
+++ b/connection.go
@@ -314,13 +314,32 @@ func (cn *connection) requestedMetadataPiece(index int) bool {
        return index < len(cn.metadataRequests) && cn.metadataRequests[index]
 }
 
+func clamp(min, value, max int64) int64 {
+       if min > max {
+               panic("harumph")
+       }
+       if value < min {
+               value = min
+       }
+       if value > max {
+               value = max
+       }
+       return value
+}
+
+func max(as ...int64) int64 {
+       ret := as[0]
+       for _, a := range as[1:] {
+               if a > ret {
+                       ret = a
+               }
+       }
+       return ret
+}
+
 // The actual value to use as the maximum outbound requests.
 func (cn *connection) nominalMaxRequests() (ret int) {
-       ret = cn.PeerMaxRequests
-       if ret > 64 {
-               ret = 64
-       }
-       return
+       return int(clamp(1, int64(cn.PeerMaxRequests), max(64, cn.stats.ChunksReadUseful-(cn.stats.ChunksRead-cn.stats.ChunksReadUseful))))
 }
 
 func (cn *connection) onPeerSentCancel(r request) {
@@ -567,13 +586,16 @@ func nextRequestState(
                                return true
                        }
                }
+               if len(currentRequests)+len(newRequests) >= requestsHighWater {
+                       return false
+               }
                if _, ok := currentRequests[r]; !ok {
                        if newRequests == nil {
                                newRequests = make([]request, 0, requestsHighWater-len(currentRequests))
                        }
                        newRequests = append(newRequests, r)
                }
-               return len(currentRequests)+len(newRequests) < requestsHighWater
+               return true
        })
        return
 }