// solveBlock attempts to find a nonce which makes the passed block header hash
// to a value less than the target difficulty. When a successful solution is
// found true is returned and the nonce field of the passed header is updated
// with the solution. False is returned if no solution exists.
func solveBlock(header *wire.BlockHeader, targetDifficulty *big.Int) bool {
// sbResult is used by the solver goroutines to send results.
type sbResult struct {
found bool
nonce uint32
}
// solver accepts a block header and a nonce range to test. It is
// intended to be run as a goroutine.
quit := make(chan bool)
results := make(chan sbResult)
solver := func(hdr wire.BlockHeader, startNonce, stopNonce uint32) {
// We need to modify the nonce field of the header, so make sure
// we work with a copy of the original header.
for i := startNonce; i >= startNonce && i <= stopNonce; i++ {
select {
case <-quit:
return
default:
hdr.Nonce = i
hash := hdr.BlockHash()
if blockchain.HashToBig(&hash).Cmp(targetDifficulty) <= 0 {
results <- sbResult{true, i}
return
}
}
}
results <- sbResult{false, 0}
}
startNonce := uint32(0)
stopNonce := uint32(math.MaxUint32)
numCores := uint32(runtime.NumCPU())
noncesPerCore := (stopNonce - startNonce) / numCores
for i := uint32(0); i < numCores; i++ {
rangeStart := startNonce + (noncesPerCore * i)
rangeStop := startNonce + (noncesPerCore * (i + 1)) - 1
if i == numCores-1 {
rangeStop = stopNonce
}
go solver(*header, rangeStart, rangeStop)
}
for i := uint32(0); i < numCores; i++ {
result := <-results
if result.found {
close(quit)
header.Nonce = result.nonce
return true
}
}
return false
}
